Patent Application
20160340564
1. Field of the Disclosure
The following is directed to shaped abrasive particles, and more particularly, to composite shaped abrasive particles having certain features and methods of forming such composite shaped abrasive particles.
2. Description of the Related Art
Abrasive articles incorporating abrasive particles are useful for various material removal operations including grinding, finishing, polishing, and the like. Depending upon the type of abrasive material, such abrasive particles can be useful in shaping or grinding various materials in the manufacturing of goods. Certain types of abrasive particles have been formulated to date that have particular geometries, such as triangular shaped abrasive particles and abrasive articles incorporating such objects. See, for example, U.S. Pat. Nos. 5,201,916; 5,366,523; and 5,984,988.
Previously, three basic technologies that have been employed to produce abrasive particles having a specified shape, which are fusion, sintering, and chemical ceramic. In the fusion process, abrasive particles can be shaped by a chill roll, the face of which may or may not be engraved, a mold into which molten material is poured, or a heat sink material immersed in an aluminum oxide melt. See, for example, U.S. Pat. No. 3,377,660. In sintering processes, abrasive particles can be formed from refractory powders having a particle size of up to 10 micrometers in diameter. Binders can be added to the powders along with a lubricant and a suitable solvent to form a mixture that can be shaped into platelets or rods of various lengths and diameters. See, for example, U.S. Pat. No. 3,079,242. Chemical ceramic technology involves converting a colloidal dispersion or hydrosol (sometimes called a sol) to a gel or any other physical state that restrains the mobility of the components, drying, and firing to obtain a ceramic material. See, for example, U.S. Pat. Nos. 4,744,802 and 4,848,041. Other relevant disclosures on shaped abrasive particles and associated methods of forming and abrasive articles incorporating such particles are available at: http://www.abel-ip.com/publications/.
The industry continues to demand improved abrasive materials and abrasive articles.
According to a first aspect, an abrasive particle includes a body having at least one microstructural characteristic including:
In yet another aspect, an abrasive particle includes a body having an average crystal size of not greater than 6 microns, a primary deformation amplitude of not greater than 30 percent.
For yet another aspect, an abrasive particle comprises a body having a hardness of at least 20 GPa, a primary deformation amplitude of not greater than 30 percent.
Still, in one aspect, an abrasive particle includes a shaped abrasive particle including a body having a primary deformation amplitude and time multiplier of not greater than 700 percent minutes.
According to another aspect, an abrasive particle comprises a body including a first dopant comprising magnesium and a second dopant comprising at least one element of the group consisting of yttrium, lanthanum, a rare-earth element, wherein the body comprises a greater content of the second dopant compared to a content of the first dopant, and a primary deformation amplitude of not greater than 9 percent.
For another aspect, an abrasive particle comprises a body including a first dopant comprising magnesium and a grain boundary phase comprising at least one of yttrium, lanthanum, and a rare-earth element combined with aluminum and oxygen.
The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings.
The following is directed to abrasive particles, including but not limited to, shaped abrasive particles. The shaped abrasive particles may be utilized in various applications, including for example coated abrasives, bonded abrasives, free abrasives, and a combination thereof. Various other uses may be derived for the shaped abrasive particles.
Various methods may be utilized to obtain shaped abrasive particles. The particles may be obtained from a commercial source or fabricated. Some suitable processes used to fabricate the shaped abrasive particles can include, but is not limited to, depositing, printing (e.g., screen-printing), molding, pressing, casting, sectioning, cutting, dicing, punching, pressing, drying, curing, coating, extruding, rolling, and a combination thereof.
The mixture 101 may contain a certain content of solid material, liquid material, and additives such that it has suitable rheological characteristics for manipulation according to the desired shaping process. The mixture can have suitable rheological characteristics that form a dimensionally stable phase of material that can be formed through the shaping process. A dimensionally stable phase of material is a material that can be formed to have a particular shape and substantially maintain the shape for at least a portion of the processing subsequent to forming. In certain instances, the shape may be retained throughout subsequent processing, such that the shape initially provided in the forming process is present in the finally-formed object. In some instances, the mixture 101 may not be a shape-stable material during and after the forming process, and the process may rely upon solidification and stabilization of the mixture 101 by further processing, such as drying.
The mixture 101 can be formed to have a particular content of solid material, such as the ceramic powder material. For example, in one embodiment, the mixture 101 can have a solids content of at least about 25 wt %, such as at least about 35 wt %, or even at least about 38 wt % for the total weight of the mixture 101. Still, in at least one non-limiting embodiment, the solids content of the mixture 101 can be not greater than about 75 wt %, such as not greater than about 70 wt %, not greater than about 65 wt %, not greater than about 55 wt %, not greater than about 45 wt %, or not greater than about 42 wt %. It will be appreciated that the content of the solids materials in the mixture 101 can be within a range between any of the minimum and maximum percentages noted above.
According to one embodiment, the ceramic powder material can include an oxide, a nitride, a carbide, a boride, an oxycarbide, an oxynitride, and a combination thereof. In particular instances, the ceramic material can include alumina. More specifically, the ceramic material may include a boehmite material, which may be a precursor of alpha alumina. The term “boehmite” is generally used herein to denote alumina hydrates including mineral boehmite, typically being Al2O3.H2O and having a water content on the order of 15%, as well as pseudoboehmite, having a water content higher than 15%, such as 20-38% by weight. It is noted that boehmite (including pseudoboehmite) has a particular and identifiable crystal structure, and therefore a unique X-ray diffraction pattern. As such, boehmite is distinguished from other aluminous materials including other hydrated aluminas such as ATH (aluminum trihydroxide), a common precursor material used herein for the fabrication of boehmite particulate materials.
Furthermore, the mixture 101 can be formed to have a particular content of liquid material. Some suitable liquids may include water. In accordance with one embodiment, the mixture 101 can be formed to have a liquid content less than the solids content of the mixture 101. In more particular instances, the mixture 101 can have a liquid content of at least about 25 wt % for the total weight of the mixture 101. In other instances, the amount of liquid within the mixture 101 can be greater, such as at least about 35 wt %, at least about 45 wt %, at least about 50 wt %, or even at least about 58 wt %. Still, in at least one non-limiting embodiment, the liquid content of the mixture can be not greater than about 75 wt %, such as not greater than about 70 wt %, not greater than about 65 wt %, not greater than about 62 wt %, or even not greater than about 60 wt %. It will be appreciated that the content of the liquid in the mixture 101 can be within a range between any of the minimum and maximum percentages noted above.
Furthermore, to facilitate processing and forming shaped abrasive particles according to embodiments herein, the mixture 101 can have a particular storage modulus. For example, the mixture 101 can have a storage modulus of at least about 1×104 Pa, such as at least about 4×104 Pa, or even at least about 5×104 Pa. However, in at least one non-limiting embodiment, the mixture 101 may have a storage modulus of not greater than about 1×107 Pa, such as not greater than about 2×106 Pa. It will be appreciated that the storage modulus of the mixture 101 can be within a range between any of the minimum and maximum values noted above.
The storage modulus can be measured via a parallel plate system using ARES or AR-G2 rotational rheometers, with Peltier plate temperature control systems. For testing, the mixture 101 can be extruded within a gap between two plates that are set to be approximately 8 mm apart from each other. After extruding the gel into the gap, the distance between the two plates defining the gap is reduced to 2 mm until the mixture 101 completely fills the gap between the plates. After wiping away excess mixture, the gap is decreased by 0.1 mm and the test is initiated. The test is an oscillation strain sweep test conducted with instrument settings of a strain range between 0.01% to 100%, at 6.28 rad/s (1 Hz), using 25-mm parallel plate and recording 10 points per decade. Within 1 hour after the test completes, the gap is lowered again by 0.1 mm and the test is repeated. The test can be repeated at least 6 times. The first test may differ from the second and third tests. Only the results from the second and third tests for each specimen should be reported.
Furthermore, to facilitate processing and forming shaped abrasive particles according to embodiments herein, the mixture 101 can have a particular viscosity. For example, the mixture 101 can have a viscosity of at least about 2×103 Pa s, such as at least about 3×103 Pa s, at least about 4×103 Pa s, at least about 5×103 Pa s, at least about 6×103 Pa s, at least about 8×103 Pa s, at least about 10×103 Pa s, at least about 20×103 Pa s, at least about 30×103 Pa s, at least about 40×103 Pa s, at least about 50×103 Pa s, at least about 60×103 Pa s, or at least about 65×103 Pa s. In at least one non-limiting embodiment, the mixture 101 may have a viscosity of not greater than about 100×103 Pa s, such as not greater than about 95×103 Pa s, not greater than about 90×103 Pa s, or even not greater than about 85×103 Pa s. It will be appreciated that the viscosity of the mixture 101 can be within a range between any of the minimum and maximum values noted above. The viscosity can be measured in the same manner as the storage modulus as described above.
Moreover, the mixture 101 can be formed to have a particular content of organic materials including, for example, organic additives that can be distinct from the liquid to facilitate processing and formation of shaped abrasive particles according to the embodiments herein. Some suitable organic additives can include stabilizers, binders such as fructose, sucrose, lactose, glucose, UV curable resins, and the like.
Notably, the embodiments herein may utilize a mixture 101 that can be distinct from slurries used in conventional forming operations. For example, the content of organic materials within the mixture 101 and, in particular, any of the organic additives noted above, may be a minor amount as compared to other components within the mixture 101. In at least one embodiment, the mixture 101 can be formed to have not greater than about 30 wt % organic material for the total weight of the mixture 101. In other instances, the amount of organic materials may be less, such as not greater than about 15 wt %, not greater than about 10 wt %, or even not greater than about 5 wt %. Still, in at least one non-limiting embodiment, the amount of organic materials within the mixture 101 can be at least about 0.01 wt %, such as at least about 0.5 wt % for the total weight of the mixture 101. It will be appreciated that the amount of organic materials in the mixture 101 can be within a range between any of the minimum and maximum values noted above.
Moreover, the mixture 101 can be formed to have a particular content of acid or base, distinct from the liquid content, to facilitate processing and formation of shaped abrasive particles according to the embodiments herein. Some suitable acids or bases can include nitric acid, sulfuric acid, citric acid, chloric acid, tartaric acid, phosphoric acid, ammonium nitrate, and ammonium citrate. According to one particular embodiment in which a nitric acid additive is used, the mixture 101 can have a pH of less than about 5, and more particularly, can have a pH within a range between about 2 and about 4.
The system 150 of
The tool 151 may be formed of a metal material, including for example, a metal alloy, such as stainless steel. In other instances, the tool 151 may be formed of an organic material, such as a polymer.
In accordance with an embodiment, a particular pressure may be utilized during extrusion. For example, the pressure can be at least about 10 kPa, such as at least about 500 kPa. Still, in at least one non-limiting embodiment, the pressure utilized during extrusion can be not greater than about 4 MPa. It will be appreciated that the pressure used to extrude the mixture 101 can be within a range between any of the minimum and maximum values noted above. In particular instances, the consistency of the pressure delivered by a piston 199 may facilitate improved processing and formation of shaped abrasive particles. Notably, controlled delivery of consistent pressure across the mixture 101 and across the width of the die 103 can facilitate improved processing control and improved dimensional characteristics of the shaped abrasive particles.
Prior to depositing the mixture 101 in the tool cavities 152, a mold release agent can be applied to the surfaces of the tool cavities 152, which may facilitate removal of precursor shaped abrasive particles from the tool cavities 152 after further processing. Such a process can be optional and may not necessarily be used to conduct the molding process. A suitable exemplary mold release agent can include an organic material, such as one or more polymers (e.g., PTFE). In other instances, an oil (synthetic or organic) may be applied as a mold release agent to the surfaces of the tool cavities 152. A suitable oil may be peanut oil. The mold release agent may be applied using any suitable manner, including but not limited to, depositing, spraying, printing, brushing, coating, and the like.
The mixture 101 may be deposited within the tool cavities 152, which may be shaped in any suitable manner to form shaped abrasive particles having shapes corresponding to the shape of the tool cavities 152.
Referring briefly to
While the tool 151 of
Moreover, the first row 156 of tool cavities 152 can be oriented relative to a direction of translation to facilitate particular processing and controlled formation of shaped abrasive particles. For example, the tool cavities 152 can be arranged on the tool 151 such that the first plane 155 of the first row 156 defines an angle relative to the direction of translation 171. As illustrated, the first plane 155 can define an angle that is substantially orthogonal to the direction of translation 171. Still, it will be appreciated that in one embodiment, the tool cavities 152 can be arranged on the tool 151 such that the first plane 155 of the first row 156 defines a different angle with respect to the direction of translation, including for example, an acute angle or an obtuse angle. Still, it will be appreciated that the tool cavities 152 may not necessarily be arranged in rows. The tool cavities 152 may be arranged in various particular ordered distributions with respect to each other on the tool 151, such as in the form of a two-dimensional pattern. Alternatively, the openings may be disposed in a random manner on the tool 151.
Referring again to
In the molding process, the mixture 101 may undergo significant drying while contained in the tool cavity 152. Therefore, shaping may be primarily attributed to substantial drying and solidification of the mixture 101 in the tool cavities 152 to shape the mixture 101. In certain instances, the shaped abrasive particles formed according to the molding process may exhibit shapes more closely replicating the features of the mold cavity compared to other processes, including for example, screen printing processes. However, it should be noted that certain beneficial shape characteristics may be more readily achieved through screen printing processes.
After applying the mold release agent, the mixture 101 can be deposited within the mold cavities and dried. Drying may include removal of a particular content of certain materials from the mixture 101, including volatiles, such as water or organic materials. In accordance with an embodiment, the drying process can be conducted at a drying temperature of not greater than about 300° C., such as not greater than about 250° C., not greater than about 200° C., not greater than about 150° C., not greater than about 100° C., not greater than about 80° C., not greater than about 60° C., not greater than about 40° C., or even not greater than about 30° C. Still, in one non-limiting embodiment, the drying process may be conducted at a drying temperature of at least about −20° C., such as at least about −10° C. at least about 0° C. at least about 5° C. at least about 10° C., or even at least about 20° C. It will be appreciated that the drying temperature may be within a range between any of the minimum and maximum temperatures noted above.
In certain instances, drying may be conducted for a particular duration to facilitate the formation of shaped abrasive particles according to embodiments herein. For example, drying can be conducted for a duration of at least about 1 minute, such as at least about 2 minutes, at least about 4 minutes, at least about 6 minutes, at least about 8 minutes, at least about 10 minutes, such as at least about 30 minutes, at least about 1 hour, at least about 2 hours, at least about 4 hours, at least about 8 hours, at least about 12 hours, at least about 15 hours, at least about 18 hours, at least about 24 hours. In still other instances, the process of drying may be not greater than about 30 hours, such as not greater than about 24 hours, not greater than about 20 hours, not greater than about 15 hours, not greater than about 12 hours, not greater than about 10 hours, not greater than about 8 hours, not greater than about 6 hours, not greater than about 4 hours. It will be appreciated that the duration of drying can be within a range between any of the minimum and maximum values noted above.
Additionally, drying may be conducted at a particular relative humidity to facilitate formation of shaped abrasive particles according to the embodiments herein. For example, drying may be conducted at a relative humidity of at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, such as at least about 62%, at least about 64%, at least about 66%, at least about 68%, at least about 70%, at least about 72%, at least about 74%, at least about 76%, at least about 78%, or even at least about 80%. In still other non-limiting embodiments, drying may be conducted at a relative humidity of not greater than about 90%, such as not greater than about 88%, not greater than about 86%, not greater than about 84%, not greater than about 82%, not greater than about 80%, not greater than about 78%, not greater than about 76%, not greater than about 74%, not greater than about 72%, not greater than about 70%, not greater than about 65%, not greater than about 60%, not greater than about 55%, not greater than about 50%, not greater than about 45%, not greater than about 40%, not greater than about 35%, not greater than about 30%, or even not greater than about 25%. It will be appreciated that the relative humidity utilized during drying can be within a range between any of the minimum and maximum percentages noted above.
After completing the drying process, the mixture 101 can be released from the tool cavities 152 to produce precursor shaped abrasive particles. Notably, before the mixture 101 is removed from the tool cavities 152 or after the mixture 101 is removed and the precursor shaped abrasive particles are formed, one or more post-forming processes may be completed. Such processes can include surface shaping, curing, reacting, radiating, planarizing, calcining, sintering, sieving, doping, and a combination thereof. For example, in one optional process, the mixture 101 or precursor shaped abrasive particles may be translated through an optional shaping zone, wherein at least one exterior surface of the mixture or precursor shaped abrasive particles may be shaped. In still another embodiment, the mixture 101 as contained in the mold cavities or the precursor shaped abrasive particles may be translated through an optional application zone, wherein a dopant material can be applied. In particular instances, the process of applying a dopant material can include selective placement of the dopant material on at least one exterior surface of the mixture 101 or precursor shaped abrasive particles.
The dopant material may be applied utilizing various methods including for example, spraying, dipping, depositing, impregnating, transferring, punching, cutting, pressing, crushing, and any combination thereof. In accordance with an embodiment, applying a dopant material can include the application of a particular material, such as a precursor. In certain instances, the precursor can be a salt, such as a metal salt, that includes a dopant material to be incorporated into the finally-formed shaped abrasive particles. For example, the metal salt can include an element or compound that is the precursor to the dopant material. It will be appreciated that the salt material may be in liquid form, such as in a dispersion comprising the salt and liquid carrier. The salt may include nitrogen, and more particularly, can include a nitrate. In other embodiments, the salt can be a chloride, sulfate, phosphate, and a combination thereof. In one embodiment, the salt can include a metal nitrate, and more particularly, consist essentially of a metal nitrate. Suitable dopant materials are described in more detail herein.
The forming process may further include a sintering process. For certain embodiments herein, sintering can be conducted after removing the mixture from the tool cavities 152 and forming the precursor shaped abrasive particles. Sintering of the precursor shaped abrasive particles 123 may be utilized to densify the particles, which are generally in a green state. In a particular instance, the sintering process can facilitate the formation of a high-temperature phase of the ceramic material. For example, in one embodiment, the precursor shaped abrasive particles may be sintered such that a high-temperature phase of alumina, such as alpha alumina, is formed. In one instance, a shaped abrasive particle can comprise at least about 90 wt % alpha alumina for the total weight of the particle. In other instances, the content of alpha alumina may be greater such that the shaped abrasive particle may consist essentially of alpha alumina.
The abrasive particles of the embodiments herein can include particular types of abrasive particle. For example, the abrasive particles may include shaped abrasive particles and/or non-shaped abrasive particles. Various methods may be utilized to obtain shaped abrasive particles as described herein. Non-shaped abrasive particles may be formed through crushing and sieving techniques.
The shaped abrasive particles of the embodiments herein, including thin shaped abrasive particles can have a primary aspect ratio of length:width such that the length can be greater than or equal to the width. Furthermore, the length of the body 201 can be greater than or equal to the height. Finally, the width of the body 201 can be greater than or equal to the height. In accordance with an embodiment, the primary aspect ratio of length:width can be at least 1:1, such as at least 1.1:1, at least 1.2:1, at least 1.5:1, at least 1.8:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 6:1, or even at least 10:1. In another non-limiting embodiment, the body 201 of the shaped abrasive particle can have a primary aspect ratio of length:width of not greater than 100:1, not greater than 50:1, not greater than 10:1, not greater than 6:1, not greater than 5:1, not greater than 4:1, not greater than 3:1, not greater than 2:1, or even not greater than 1:1. It will be appreciated that the primary aspect ratio of the body 201 can be with a range including any of the minimum and maximum ratios noted above.
Furthermore, the body 201 can have a secondary aspect ratio of width:height that can be at least 1:1, such as at least 1.1:1, at least 1.2:1, at least 1.5:1, at least 1.8:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 8:1, or even at least 10:1. Still, in another non-limiting embodiment, the secondary aspect ratio width:height of the body 201 can be not greater than 100:1, such as not greater than 50:1, not greater than 10:1, not greater than 8:1, not greater than 6:1, not greater than 5:1, not greater than 4:1, not greater than 3:1, or even not greater than 2:1. It will be appreciated the secondary aspect ratio of width:height can be with a range including any of the minimum and maximum ratios of above.
In another embodiment, the body 201 can have a tertiary aspect ratio of length:height that can be at least 1.1:1, such as at least 1.2:1, at least 1.5:1, at least 1.8:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 8:1, or even at least 10:1. Still, in another non-limiting embodiment, the tertiary aspect ratio length:height of the body 201 can be not greater than 100:1, such as not greater than 50:1, not greater than 10:1, not greater than 8:1, not greater than 6:1, not greater than 5:1, not greater than 4:1, not greater than 3:1. It will be appreciated that the tertiary aspect ratio the body 201 can be with a range including any of the minimum and maximum ratios and above.
The abrasive particles of the embodiments herein, including the shaped abrasive particles can include a crystalline material, and more particularly, a polycrystalline material. Notably, the polycrystalline material can include abrasive grains. In one embodiment, the body of the abrasive particle, including for example, the body of a shaped abrasive particle can be essentially free of an organic material, such as, a binder. In at least one embodiment, the abrasive particles can consist essentially of a polycrystalline material.
It may be possible to form the abrasive particles of materials including nitrides, oxides, carbides, borides, oxynitrides, oxyborides, diamond, carbon-containing materials, and a combination thereof. In particular instances, the abrasive particles can include an oxide compound or complex, such as aluminum oxide, zirconium oxide, titanium oxide, yttrium oxide, chromium oxide, strontium oxide, silicon oxide, magnesium oxide, rare-earth oxides, and a combination thereof.
In one particular embodiment, the abrasive particles can include a majority content of alumina. For at least one embodiment, the abrasive particle can include at least 80 wt % alumina, such as at least 90 wt % alumina, at least 91 wt % alumina, at least 92 wt % alumina, at least 93 wt % alumina, at least 94 wt % alumina, at least 95 wt % alumina, at least 96 wt % alumina, or even at least 97 wt % alumina. Still, in at least one particular embodiment, the abrasive particle can include not greater than 99.5 wt % alumina, such as not greater than 99 wt % alumina, not greater than 98.5 wt % alumina, not greater than 97.5 wt % alumina, not greater than 97 wt % alumina not greater than 96 wt % alumina, or even not greater than 94 wt % alumina. It will be appreciated that the abrasive particles of the embodiments herein can include a content of alumina within a range including any of the minimum and maximum percentages noted above. Moreover, in particular instances, the shaped abrasive particles can be formed from a seeded sol-gel. In at least one embodiment, the abrasive particles can consist essentially of alumina and certain dopant materials as described herein.
The abrasive particles of the embodiments herein can include particularly dense bodies, which may be suitable for use as abrasives. For example, the abrasive particles may have a body having a density of at least 95% theoretical density, such as at least 96% theoretical density, at least 97% theoretical density, at least 98% theoretical density or even at least 99% theoretical density.
The abrasive grains (i.e., crystallites) contained within the body of the abrasive particles may have an average grain size (i.e., average crystal size) that is generally not greater than about 100 microns. In other embodiments, the average grain size can be less, such as not greater than about 80 microns or not greater than about 50 microns or not greater than about 30 microns or not greater than about 20 microns or not greater than about 10 microns or not greater than 6 microns or not greater than 5 microns or not greater than 4 microns or not greater than 3.5 microns or not greater than 3 microns or not greater than 2.5 microns or not greater than 2 microns or not greater than 1.5 microns or not greater than 1 micron or not greater than 0.8 microns or not greater than 0.6 microns or not greater than 0.5 microns or not greater than 0.4 microns or not greater than 0.3 microns or even not greater than 0.2 microns. Still, the average grain size of the abrasive grains contained within the body of the abrasive particle can be at least about 0.01 microns, such as at least about 0.05 microns or at least about 0.06 microns or at least about 0.07 microns or at least about 0.08 microns or at least about 0.09 microns or at least about 0.1 microns or at least about 0.12 microns or at least about 0.15 microns or at least about 0.17 microns or at least about 0.2 microns or even at least about 0.3 microns. It will be appreciated that the abrasive particles can have an average grain size (i.e., average crystal size) within a range between any of the minimum and maximum values noted above.
The average grain size (i.e., average crystal size) can be measured based on the uncorrected intercept method using scanning electron microscope (SEM) photomicrographs. Samples of abrasive grains are prepared by making a bakelite mount in epoxy resin then polished with diamond polishing slurry using a Struers Tegramin 30 polishing unit. After polishing the epoxy is heated on a hot plate, the polished surface is then thermally etched for 5 minutes at 150° C. below sintering temperature. Individual grains (5-10 grits) are mounted on the SEM mount then gold coated for SEM preparation. SEM photomicrographs of three individual abrasive particles are taken at approximately 50,000× magnification, then the uncorrected crystallite size is calculated using the following steps: 1) draw diagonal lines from one corner to the opposite corner of the crystal structure view, excluding black data band at bottom of photo 2) measure the length of the diagonal lines as L1 and L2 to the nearest 0.1 centimeters; 3) count the number of grain boundaries intersected by each of the diagonal lines, (i.e., grain boundary intersections I1 and I2) and record this number for each of the diagonal lines, 4) determine a calculated bar number by measuring the length (in centimeters) of the micron bar (i.e., “bar length”) at the bottom of each photomicrograph or view screen, and divide the bar length (in microns) by the bar length (in centimeters); 5) add the total centimeters of the diagonal lines drawn on photomicrograph (L1+L2) to obtain a sum of the diagonal lengths; 6) add the numbers of grain boundary intersections for both diagonal lines (I1+I2) to obtain a sum of the grain boundary intersections; 7) divide the sum of the diagonal lengths (L1+L2) in centimeters by the sum of grain boundary intersections (I1+I2) and multiply this number by the calculated bar number. This process is completed at least three different times for three different, randomly selected samples to obtain an average crystallite size.
In accordance with certain embodiments, certain abrasive particles can be composite articles including at least two different types of grains within the body of the abrasive particle. It will be appreciated that different types of grains are grains having different compositions with regard to each other. For example, the body of the abrasive particle can be formed such that is includes at least two different types of grains, wherein the two different types of grains can be nitrides, oxides, carbides, borides, oxynitrides, oxyborides, diamond, and a combination thereof.
In accordance with an embodiment, the abrasive particles can have an average particle size, as measured by the largest dimension (i.e., length) of at least about 100 microns. In fact, the abrasive particles can have an average particle size of at least about 150 microns, such as at least about 200 microns, at least about 300 microns, at least about 400 microns, at least about 500 microns, at least about 600 microns, at least about microns, at least about 800 microns, or even at least about 900 microns. Still, the abrasive particles of the embodiments herein can have an average particle size that is not greater than about 5 mm, such as not greater than about 3 mm, not greater than about 2 mm, or even not greater than about 1.5 mm. It will be appreciated that the abrasive particles can have an average particle size within a range between any of the minimum and maximum values noted above.
The elongated abrasive particle 350 can have certain attributes of the other abrasive particles described in the embodiments herein, including for example but not limited to, composition, microstructural features (e.g., average grain size), hardness, porosity, and the like.
It will be appreciated that like the thin shaped abrasive particle of
As further illustrated in
As will be appreciated, the abrasive particle can have a length defined by longitudinal axis 352, a width defined by the lateral axis 353, and a vertical axis 354 defining a height. As will be appreciated, the body 351 can have a primary aspect ratio of length:width such that the length is equal to or greater than the width. Furthermore, the length of the body 351 can be equal to or greater than or equal to the height. Finally, the width of the body 351 can be greater than or equal to the height 354. In accordance with an embodiment, the primary aspect ratio of length:width can be at least 1.1:1, at least 1.2:1, at least 1.5:1, at least 1.8:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 6:1, or even at least 10:1. In another non-limiting embodiment, the body 351 of the elongated shaped abrasive particle can have a primary aspect ratio of length:width of not greater than 100:1, not greater than 50:1, not greater than 10:1, not greater than 6:1, not greater than 5:1, not greater than 4:1, not greater than 3:1, or even not greater than 2:1. It will be appreciated that the primary aspect ratio of the body 351 can be with a range including any of the minimum and maximum ratios noted above.
Furthermore, the body 351 of the elongated abrasive particle 350 can include a secondary aspect ratio of width:height that can be at least 1.1:1, such as at least 1.2:1, at least 1.5:1, at least 1.8:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 8:1, or even at least 10:1. Still, in another non-limiting embodiment, the secondary aspect ratio width:height of the body 351 can be not greater than 100:1, such as not greater than 50:1, not greater than 10:1, not greater than 8:1, not greater than 6:1, not greater than 5:1, not greater than 4:1, not greater than 3:1, or even not greater than 2:1. It will be appreciated the secondary aspect ratio of width:height can be with a range including any of the minimum and maximum ratios of above.
In another embodiment, the body 351 of the elongated abrasive particle 350 can have a tertiary aspect ratio of length:height that can be at least 1.1:1, such as at least 1.2:1, at least 1.5:1, at least 1.8:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 8:1, or even at least 10:1. Still, in another non-limiting embodiment, the tertiary aspect ratio length:height of the body 351 can be not greater than 100:1, such as not greater than 50:1, not greater than 10:1, not greater than 8:1, not greater than 6:1, not greater than 5:1, not greater than 4:1, not greater than 3:1, It will be appreciated that the tertiary aspect ratio the body 351 can be with a range including any of the minimum and maximum ratios and above.
The elongated abrasive particle 350 can have certain attributes of the other abrasive particles described in the embodiments herein, including for example but not limited to, composition, microstructural features (e.g., average grain size), hardness, porosity, and the like.
As illustrated, the body 401 can have a perimeter defined by at least one linear section and at least one arcuate section. More particularly, the body 401 can include a first portion 406 including a first curved section 442 disposed between a first linear section 441 and a second linear section 443 and between the external corners 409 and 410. The second portion 407 is separated from the first portion 406 of the side surface 405 by the external corner 410. The second portion 407 of the side surface 405 can include a second curved section 452 joining a third linear section 451 and a fourth linear section 453. Furthermore, the body 401 can include a third portion 408 separated from the first portion 406 of the side surface 405 by the external corner 409 and separated from the second portion 407 by the external corner 411. The third portion 408 of the side surface 405 can include a third curved section 462 joining a fifth linear section 461 and a sixth linear section 463. In at least one embodiment, the body 401 may be a shape including a central region having three arms extending from the central region, each of the arms including tips including external corners (e.g., 409, 410, and 411) defined by a joint between two linear sections and at least one arcuate portion extending between two external corners. Moreover, as illustrated in
The shaped abrasive particles of the embodiments herein may have a particular tip sharpness that may facilitate suitable performance in the fixed abrasive articles of the embodiments herein. For example, the body of a shaped abrasive particle can have a tip sharpness of not greater than 80 microns, such as not greater than 70 microns, not greater than 60 microns, not greater than 50 microns, not greater than 40 microns, not greater than 30 microns, not greater than 20 microns, or even not greater than 10 microns. In yet another non-limiting embodiment, the tip sharpness can be at least 2 microns, such as at least 4 microns, at least 10 microns, at least 20 microns, at least 30 microns, at least 40 microns, at least 50 microns, at least 60 microns, or even at least 70 microns. It will be appreciated that the body can have a tip sharpness within a range between any of the minimum and maximum values noted above.
Another grain feature of shaped abrasive particles is the Shape Index. The Shape Index of a body of a shaped abrasive particle can be described as a value of an outer radius of a best-fit outer circle superimposed on the body, as viewed in two dimensions of a plane of length and width of the body (e.g., the upper major surface or the bottom major surface), compared to an inner radius of the largest best-fit inner circle that fits entirely within the body, as viewed in the same plane of length and width. For example, turning to
A second, inner circle can be superimposed on the body 470, as illustrated in
The Shape Index can be calculated by dividing the outer radius by the inner radius (i.e., Shape Index=Ri/Ro). For example, the body 470 of the shaped abrasive particle has a Shape Index of approximately 0.35. Moreover, an equilateral triangle generally has a Shape Index of approximately 0.5, while other polygons, such as a hexagon or pentagon have Shape Index values greater than 0.5. In accordance with an embodiment, the shaped abrasive particles herein can have a Shape Index of at least 0.02, such as at least 0.05, at least 0.10, at least 0.15, at least 0.20, at least 0.25, at least 0.30, at least 0.35, at least 0.40, at least 0.45, at least about 0.5, at least about 0.55, at least 0.60, at least 0.65, at least 0.70, at least 0.75, at least 0.80, at least 0.85, at least 0.90, at least 0.95. Still, in another non-limiting embodiment, the shaped abrasive particle can have a Shape Index of not greater than 1, such as not greater than 0.98, not greater than 0.95, not greater than 0.90, not greater than 0.85, not greater than 0.80, not greater than 0.75, not greater than 0.70, not greater than 0.65, not greater than 0.60, not greater than 0.55, not greater than 0.50, not greater than 0.45, not greater than 0.40, not greater than 0.35, not greater than 0.30, not greater than 0.25, not greater than 0.20, not greater than 0.15, not greater than 0.10, not greater than 0.05, not greater than 0.02. It will be appreciated that the shaped abrasive particles can have a Shape Index within a range between any of the minimum and maximum values noted above.
The abrasive particles of the embodiments herein, which may include shaped abrasive particles and/or non-shaped abrasive particles, can have a particular composition that facilitates improved characteristics, including for example, a combination of suitable density and abrasive capabilities combined with a certain creep behavior. In particular, the abrasive particles can have a body including a first dopant, which may facilitate sintering and densification of the body and/or the formation of one or more additional phases in the body during sintering that facilitate the abrasive characteristics of the body. In one embodiment, the first dopant may include cobalt, magnesium, and a combination thereof. In more particular instances, the first dopant can include a majority content of magnesium and oxygen, and even more particularly, may consist essentially of magnesium and oxygen. For example, the first dopant can be magnesium oxide (MgO), and may consist essentially of magnesium oxide. In still another embodiment, the first dopant may include cobalt and oxygen, and may consist essentially of cobalt and oxygen.
In certain instances, the body of the abrasive particle can have a particular content of the first dopant that may facilitate the improved characteristics. For example, the body can include at least 0.1 wt % of the first dopant for the total weight of the body, such as at least 0.12 wt % or at least 0.15 wt % or at least 0.18 wt % or at least 0.2 wt % or at least 0.3 wt % or at least 0.4 wt % or at least 0.5 wt % or at least 0.6 wt % or at least 0.7 wt % or at least 0.8 wt % or at least 0.9 wt %. In yet another embodiment, the body of an abrasive particle may include not greater than 4.5 wt % of the first dopant for the total weight of the body, such as not greater than 4 wt % or not greater than 3 wt % or not greater than 2.5 wt % or not greater than 2.2 wt % or not greater than 2 wt % or not greater than 1.9 wt % or not greater than 1.8 wt % or not greater than 1.7 wt % or not greater than 1.6 wt % or not greater than 1.5 wt % or not greater than 1.4 wt % or not greater than 1.3 wt % or even not greater than 1.2 wt %. It will be appreciated that the body can include a content of the first dopant within a range including any of the minimum and maximum values noted above. Reference herein to the content of dopant material within a body of an abrasive particle can also be reference to an average content of the dopant for a group of abrasive particles, including for example a group of abrasive particles included in a fixed abrasive article. Moreover, different contents of the first dopant may be used to affect different behaviors. For example, smaller contents of the first dopant may be used to affect the densification of the body, wherein greater contents of the first dopant may be used to affect the abrasive behavior of the body.
In another aspect, the body of an abrasive particle can include a second dopant, which is distinct in composition from the first dopant by at least one element and which may also be distinct from the first dopant in terms of the distribution and/or placement within the body of the abrasive particle. The provision of a second dopant may facilitate certain improved characteristics of the abrasive particle, including for example, but not limited to creep and deformation characteristics related to improved grinding performance. According to one embodiment, the second dopant can include at least one element from the group consisting of yttrium, lanthanum, a rare-earth element, and a combination thereof. Rare-earth elements include those elements regarded as rare-earth elements according to the Periodic Table of Elements, which can include the seventeen elements including 15 lanthanide elements as well as scandium, and yttrium.
In at least one embodiment, the second dopant can include a material such as yttrium, and more particularly yttrium and oxygen, which may be in the form of a compound, such as yttrium oxide. In one particular instance, the second dopant can consist essentially of yttrium and oxygen. Other suitable materials which may be used as the second dopant can include zirconium, lanthanum, strontium, lutetium, neodymium, and a combination thereof.
In certain instances, the body can include a particular content of the second dopant to facilitate improved characteristics. For example, the body of the abrasive particle may include at least 0.1 wt % of the second dopant for the total weight of the body, such as at least 0.2 wt % or at least 0.4 wt % or at least 0.6 wt % or at least 0.8 wt % or at least 1 wt % or at least 1.1 wt % or at least 1.2 wt % or at least 1.3 wt % or at least 1.4 wt % or at least 1.5 wt % or at least 1.6 wt % or at least 1.7 wt % or at least 1.8 wt % or at least 1.9 wt % or even at least 2 wt %. Still, in one non-limiting embodiment, the body of the abrasive particle can include not greater than 10 wt % of the second dopant for the total weight of the body, such as not greater than 9 wt % or not greater than 8 wt % or not greater than 7 wt % or not greater than 6 wt % or not greater than 5 wt % or not greater than 4 wt % or not greater than 3.5 wt % or not greater than 3.2 wt % or not greater than 3 wt % or not greater than 2.9 wt % or not greater than 2.8 wt % or not greater than 2.7 wt % or not greater than 2.6 wt % or not greater than 2.5 wt % or not greater than 2.4 wt % or not greater than 2.3 wt % or not greater than 2.2 wt % or even not greater than 2.1 wt %. It will be appreciated that the body of the abrasive particle can have a content of the second dopant within a range including any of the minimum and maximum percentages noted above. Further, it will be appreciated that reference to any of the percentages can be reference to an average percentage for a group or batch of abrasive particles, such as a group of abrasive particles incorporated into a fixed abrasive article.
According to at least one embodiment, the abrasive particle may utilize a relative content of the first and second dopants, which may facilitate improved characteristics and performance. For example, the abrasive particle may include a dopant ratio value (D1/D2) of at least 1, wherein D1 represents the weight percent of the first dopant in the body and D2 represent the weight percent of the second dopant in the body. In still other instances, the dopant ratio value (D1/D2) can be greater than 1, such as at least 1.1 or at least 1.2 or at least 1.3 or at least 1.4 or at least 1.5 or at least 1.6 or at least 1.7 or at least 1.8 or at least 1.9 or even at least 2. Still, in one non-limiting embodiment, the dopant ratio value (D1/D2) can be not greater than 10, such as not greater than 9 or not greater than 8 or not greater than 7 or not greater than 6 or not greater than 5 or not greater than 4 or not greater than 3.5 or not greater than 3 or not greater than 2.8 or not greater than 2.5. It will be appreciated that the body of the abrasive particle can have a dopant ratio (D1/D2) within a range including any of the minimum and maximum values noted above. Furthermore, it will be appreciated that reference to any of the values can be reference to an average value for a group or batch of abrasive particles, such as a group of abrasive particles incorporated into a fixed abrasive article.
In still other instances, the abrasive particle may utilize a relative content of the first and second dopants, which differs from the ratios noted above, and which may also facilitate improved characteristics and performance. For example, the abrasive particle may include a dopant ratio value (D2/D1) of at least 1, wherein D1 represents the weight percent of the first dopant in the body and D2 represent the weight percent of the second dopant in the body. In still other instances, the dopant ratio value (D2/D1) can be greater than 1, such as at least 1.1 or at least 1.2 or at least 1.3 or at least 1.4 or at least 1.5 or at least 1.6 or at least 1.7 or at least 1.8 or at least 1.9 or even at least 2. Still, in one non-limiting embodiment, the dopant ratio value (D2/D1) can be not greater than 10, such as not greater than 9 or not greater than 8 or not greater than 7 or not greater than 6 or not greater than 5 or not greater than 4 or not greater than 3.5 or not greater than 3 or not greater than 2.8 or not greater than 2.5. It will be appreciated that the body of the abrasive particle can have a dopant ratio (D2/D1) within a range including any of the minimum and maximum values noted above. Furthermore, it will be appreciated that reference to any of the values can be reference to an average value for a group or batch of abrasive particles, such as a group of abrasive particles incorporated into a fixed abrasive article.
According to one embodiment, the abrasive particle may be formed to have a particular distribution of the first dopant and/or second dopant within the body of the abrasive particle. For example, in certain instances, the first dopant can present as a first grain boundary phase and the second dopant can be present as a second grain boundary phase. Grain boundary phases may exist between the grains (i.e., crystallites) of other grains of material within the body, which may include for example, grains comprising alumina. The grain boundary phases may include one or more elements from one or more of the dopant materials. In one embodiment, the first grain boundary phase can be substantially homogeneous throughout the entire body of the abrasive particle. In more particular instances, the first grain boundary phase can be substantially homogeneous throughout the entire body of the abrasive particle. According to another aspect, the second grain boundary phase can be substantially homogeneous throughout the entire body of the abrasive particle.
Still, in at least one embodiment, the body of the abrasive particle can include a non-homogeneous distribution of the first and/or second dopant. For example, in one embodiment, at least one of the first dopant and second dopant are preferentially distributed in a higher concentration near the exterior surfaces of the body compared to the interior region surrounding a volumetric midpoint of the body. For example, in one aspect, the first dopant can have a higher concentration at a peripheral region of the body including and abutting an exterior surface of the body compared to a central region within the body spaced away from the exterior surface and surrounding a midpoint of the body. Moreover, in another embodiment, the second dopant can have a higher concentration at a peripheral region of the body including and abutting an exterior surface of the body compared to a central region within the body spaced away from the exterior surface and surrounding a midpoint of the body.
Reference herein to first and second phases may be non-limiting and it will be appreciated that other phase and/or compositions can exist within the abrasive particles of the embodiments herein in addition to only a first and second phase.
According to an embodiment, the abrasive particle can include a third dopant, which may be distinct from the first and/or second dopant in composition and/or distribution within the body of the abrasive particle. The third dopant may include a metal-containing compound, such as an oxide, and more particularly, a transition metal oxide compound. One suitable metal element includes cobalt. In one particular instance, the third dopant can consist essentially of cobalt or cobalt oxide. In yet another instance, the third dopant can include zirconium, lanthanum, strontium, lutetium, neodymium, and a combination thereof.
The third dopant may be a distinct phase from other phases within the body, including for example, the phase comprising the alumina material. Still, the third dopant need not be a distinct phase of material and can be incorporated into one or more other phases of material within the body.
In certain instances, the body can include a particular content of the third dopant to facilitate improved characteristics. For example, the body can include a content of the third dopant that is different than the content of the first or second dopants. The third dopant may be present in an amount that is less than the content of the first dopant. Moreover, the third dopant may be present in an amount that is less than the amount of the second dopant. The presence of the third dopant does not necessarily require the presence of the first or second dopant, and is merely selected as a general naming convention.
The body may include a particular content of the third dopant that can facilitate improved characteristics, including but not limited to abrasive behavior and/or deformation characteristics. For example, the content of the third dopant in the body can be at least 0.1 wt % of the third dopant for the total weight of the body, such as at least 0.2 wt % or at least 0.4 wt % or at least 0.6 wt % or at least 0.8 wt % or at least 1 wt % or at least 1.1 wt % or at least 1.2 wt % or at least 1.3 wt % or at least 1.4 wt % or at least 1.5 wt % or at least 1.6 wt % or at least 1.7 wt % or at least 1.8 wt % or at least 1.9 wt % or even at least 2 wt %. Still, in one non-limiting embodiment, the body of the abrasive particle can include not greater than 10 wt % of the third dopant for the total weight of the body, such as not greater than 9 wt % or not greater than 8 wt % or not greater than 7 wt % or not greater than 6 wt % or not greater than 5 wt % or not greater than 4 wt % or not greater than 3.5 wt % or not greater than 3.2 wt % or not greater than 3 wt % or not greater than 2.9 wt % or not greater than 2.8 wt % or not greater than 2.7 wt % or not greater than 2.6 wt % or not greater than 2.5 wt % or not greater than 2.4 wt % or not greater than 2.3 wt % or not greater than 2.2 wt % or even not greater than 2.1 wt %. It will be appreciated that the body of the abrasive particle can have a content of the third dopant within a range including any of the minimum and maximum percentages noted above. Further, it will be appreciated that reference to any of the percentages can be reference to an average percentage for a group or batch of abrasive particles, such as a group of abrasive particles incorporated into a fixed abrasive article.
According to at least one embodiment, the abrasive particle may utilize a relative content of the first and third dopants, which may facilitate improved characteristics and/or performance. For example, the abrasive particle may include a dopant ratio value (D1/D3) of at least 1, wherein D1 represents the weight percent of the first dopant in the body and D3 represent the weight percent of the third dopant in the body. In still other instances, the dopant ratio value (D1/D3) can be greater than 1, such as at least 1.1 or at least 1.2 or at least 1.3 or at least 1.4 or at least 1.5 or at least 1.6 or at least 1.7 or at least 1.8 or at least 1.9 or even at least 2. Still, in one non-limiting embodiment, the dopant ratio value (D1/D3) can be not greater than 10, such as not greater than 9 or not greater than 8 or not greater than 7 or not greater than 6 or not greater than 5 or not greater than 4 or not greater than 3.5 or not greater than 3 or not greater than 2.8 or not greater than 2.5. It will be appreciated that the body of the abrasive particle can have a dopant ratio (D1/D3) within a range including any of the minimum and maximum values noted above. Furthermore, it will be appreciated that reference to any of the values can be reference to an average value for a group or batch of abrasive particles, such as a group of abrasive particles incorporated into a fixed abrasive article.
Moreover, the abrasive particle may utilize a relative content of the second and third dopants, which may facilitate improved characteristics and/or performance. For example, the abrasive particle may include a dopant ratio value (D2/D3) of at least 1, wherein D2 represents the weight percent of the second dopant in the body and D3 represent the weight percent of the third dopant in the body. In still other instances, the dopant ratio value (D2/D3) can be greater than 1, such as at least 1.1 or at least 1.2 or at least 1.3 or at least 1.4 or at least 1.5 or at least 1.6 or at least 1.7 or at least 1.8 or at least 1.9 or even at least 2. Still, in one non-limiting embodiment, the dopant ratio value (D2/D3) can be not greater than 10, such as not greater than 9 or not greater than 8 or not greater than 7 or not greater than 6 or not greater than 5 or not greater than 4 or not greater than 3.5 or not greater than 3 or not greater than 2.8 or not greater than 2.5. It will be appreciated that the body of the abrasive particle can have a dopant ratio (D2/D3) within a range including any of the minimum and maximum values noted above. Furthermore, it will be appreciated that reference to any of the values can be reference to an average value for a group or batch of abrasive particles, such as a group of abrasive particles incorporated into a fixed abrasive article.
According to at least one embodiment, the abrasive particle may have a particular composition that provides improved characteristics and/or performance. For example, the body can be essentially free of zirconium, cobalt, iron, calcium, carbides, nitrides, silicon, lithium, sodium, potassium, strontium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, niobium, molybdenum, ruthenium, palladium, hafnium, tantalum, lanthanum, cerium, neodymium, scandium, zinc, and a combination thereof. As used herein, a body that is “essentially free of” a material is intended to refer to a content of that material that is less than 1 wt % of the body, such as less than 0.8 wt % of the body or less than 0.6 wt % of the body or less than 0.4 wt % of the body or less than 0.3 wt % of the body or less than 0.2 wt % of the body or less than 0.1 wt % of the body or less than 0.08 wt % of the body or less than 0.06 wt % of the body or less than 0.04 wt % of the body or less than 0.03 wt % of the body or less than 0.02 wt % of the body or less than 0.01 wt % of the body. “Essentially free” can also refer to a body that is absolutely free of the material (0 wt %). Bodies “essentially free of” a material may include minor content of the material, such as impurity content, or content below a measurable limit for certain characterization tools; however, bodies which are “essentially free of” certain materials are not notably impacted by impurity content of the material. The foregoing does not limit the foregoing elements from all compositions of the embodiments herein, but provides a list of elements that may not necessarily exist within the abrasive particle in limited instances.
In at least one particular embodiment, the body may be essentially free of certain elements and compositions including such elements, including for example, but not limited to rare-earth metal elements. In more particular, terms, the body can be essentially free of praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, cerium, dysprosium, erbium, and a combination thereof.
According to one particular embodiment, the body can consist essentially of alpha alumina, magnesium-containing oxides, and at least one of a yttrium-containing oxide, lanthanum-containing oxide, and/or a rare-earth containing oxide. In the one particular embodiment, the content of alpha alumina can be greater than the content of magnesium-containing oxide within the body, and the content of the magnesium-containing oxide can be greater than the content of at least one of the yttrium-containing oxide, the lanthanum-containing oxide, and/or the rare-earth containing oxide.
In one embodiment, the body of the abrasive particle can include a grain boundary phase comprising yttrium, aluminum, and oxygen. The grain boundary phase can be located primarily, if not entirely, within the grain boundaries of the body. The grain boundary phase may be disposed between the crystallites of alumina at the grain boundaries. More particularly, the grain boundary phase can be preferentially located at triple point boundaries joining three or more crystallites. According to one embodiment, the grain boundary phase can include an oxide compound including yttrium and aluminum. For example, the grain boundary phase can include a yttrium aluminate compound, and may consist essentially of yttrium aluminate. It will be appreciated that any one of the grain boundary phases mentioned herein can include a crystalline material, a polycrystalline material and the like. Moreover, any one of the grain boundary phases noted in the embodiments herein can be bonded to the surrounding grains. Still, in certain instances, one or more different grain boundary phases may exist. In certain other instances, the body can include a grain boundary phase including spinel composition comprising magnesium, aluminum and oxygen. The grain boundary phase including the spinel composition may be present with one or more grain boundary phases described herein.
The abrasive particles of the embodiments herein can have a particular hardness that may facilitate improved performance. For example, the abrasive particles of the embodiments herein can have a Vickers hardness, as measured according to ASTM C1327 of at least 20 GPa, such as at least 20.5 GPa or at least 21 GPa or at least 21.5 GPa or even at least 22 GPa. Still, in one non-limiting embodiment, the Vickers hardness can be not greater than 40 GPa, such as not greater than 30 GPa or even not greater than 28 GPa. It will be appreciated that the abrasive particles can have a hardness within a range including any of the minimum and maximum values noted above.
The abrasive particles of the embodiments herein have demonstrated a particularly unique performance as evaluated according to a standardized creep test, which may relate to superior grinding performance. The deformation characteristics of the abrasive particles can be measured by a standardized creep test, using a ThermoMechanical Analyzer (Make: SETARAM, Model: SETSYS Evolution TMA 2400) to measure strain as a function of time, at high temperature.
During testing, the sample is placed in the heating chamber (in Argon and at atmospheric pressure) and under the probe. The temperature is measured by a thermocouple in tungsten. Temperature rises from room temperature to 1200° C. in 2 hours (10° C. per minute), is held at 1200° C. for 18 hours, and finally decreases from 1200° C. to room temperature in 2.5 hours.
Data analyses and processing are conducted by the software Calisto, which is available from Advanced Kinetics and Technology Solutions. For each campaign of test runs, a blank sample is first run in order to record the dilatation of the probe and the sample holder. A blank curve is created as a manner of calibrating the system before conducting test runs on samples. One or more standard tests are then conducted using the desired samples to create raw data curves of the creep behavior. See,
Raw data curve:
Y2(t)−Y2(0)+Y3(t)−Y3(0)+Dprobe(Y1(t))
Raw data curve minus the blank curve:
Y2(t)−Y2(0)+Y3(t)−Y3(0)+Dprobe(Y1(t))−[X3(t)−X3(0)+Dprobe(X2(t))+Dprobe(X1(t))]=Y2(t)−Y2(0)−Dprobe(X2(t))
Raw data curve minus the blank curve, corrected by the dilatation of the portion of the probe that correspond to the grain size:
Y2(t)−Y2(0)+Y3(t)−Y3(0)+Dprobe(Y1(t))−[X3(t)−X3(0)+Dprobe(X2(t))+Dprobe(X1(t))]+Dprobe(X2(t))=Y2(t)−Y2(0)
Notably, Dprobe(L) is the measure of the dilatation of a piece of the probe of length L. At certain times, the following equalities exist: Y1(t)=X1(t), Y2(t), X2(t) and Y3(t)=X3(t)
Hence, the final plot represents the strain of the grain without the influence of the probe dilatation, which may appear to have the shape generally of the plot provided in
During further analysis, the portions 630 of the plot provided in
A best first curve is then fit to each plot. Based on the generalized plot provided in
If t<thrsh: Creep curve=A*(−b+exp(−t/τ))
And the curve in the secondary regime 632 is fitted with a curve according to the equation:
If t≧thrsh: Creep curve=A*(−b+exp(−t/τ))−r*(t−thrsh)
Notably, “thrsh” represents the beginning of the secondary regime, “t” represents the time in minute, “A” represents the amplitude of the primary regime, “b” represents the affix of the exponential, “r” represents the characteristic time of the primary regime, “r” represents the rate in the secondary regime, and “c” represents the affix of the straight line. The variables, “thrsh”, “A”, “b”, “τ”, “r” and “c” are the parameters that are fitted by the model. The method used for the fit is called the least square estimation. Notably, the variable “A” defines the primary deformation amplitude in percent, “τ” represents the primary deformation time (in minutes), “r” represents the secondary deformation characteristic rate percent/minute.
In accordance with one embodiment, the abrasive particles of the embodiments herein can have one or more particular deformation characteristics, which may be evaluated according to the standardized creep test, and which may facilitate improved grinding performance. Without wishing to be tied to a particular theory, it is thought that the abrasive particles of the embodiments herein can have a certain primary deformation amplitude (A), which may indicate the likelihood of the abrasive particle to plastically deform under a load, wherein a smaller primary deformation amplitude may indicate a particle that is less likely to plastically deform and thus exhibit better grinding performance compared to a particle having a higher primary deformation amplitude (A). According to one embodiment, the abrasive particles can have a primary deformation amplitude (A) of not greater than 30 percent as calculated by the formula [(L−L0)/L0]*100, such as not greater than 25 percent or not greater than 20 percent or not greater than 18 percent or not greater than 16 percent or not greater than 14 percent or not greater than 13 percent or not greater than 12 percent or not greater than 11 percent or not greater than 10 percent or not greater than 9 percent or not greater than 8 percent or not greater than 7 percent or not greater than 6 percent or even not greater than 5 percent. Still, in one non-limiting embodiment, the primary deformation amplitude (A) can be at least 0.01 percent, such as at least 0.1 percent. It will be appreciated that the primary deformation amplitude (A) can be within a range including any of the minimum and maximum values noted above.
The abrasive particles of the embodiments herein may have a certain primary deformation time, which may be an indication of the likelihood of a particle to plastically deform, wherein a smaller primary deformation time may facilitate improved performance. For example, the abrasive particles of the embodiments herein can have a primary deformation time of not greater than 280 minutes, such as not greater than 250 minutes or not greater than 230 minutes or not greater than 200 minutes or not greater than 180 minutes or not greater than 160 minutes or even not greater than 150 minutes. Still, in at least one non-limiting embodiment, the abrasive particles can have a primary deformation time of at least 100 minutes, such as at least 110 minutes or at least 120 minutes or at least 130 minutes or even at least 140 minutes. It will be appreciated that the abrasive particles can have a primary deformation time within a range including any of the minimum and maximum values noted above.
The abrasive particles of the embodiments herein may have a certain primary deformation amplitude and time multiplier value, which may be an indication of the likelihood of a particle to plastically deform over a given time, wherein a smaller primary deformation amplitude and time multiplier may facilitate improved performance. For example, the abrasive particles of the embodiments herein can have a primary deformation amplitude and time value of not greater than 700 percent minutes as calculated by the formula [[(L−L0)/L0]*100]*min, such as not greater than 690 percent minutes or not greater than 680 percent minutes or not greater than 670 percent minutes or not greater than 660 percent minutes or not greater than 650 percent minutes or not greater than 640 percent minutes or not greater than 630 percent minutes or not greater than 620 percent minutes or not greater than 610 percent minutes or not greater than 600 percent minutes or not greater than 590 percent minutes or not greater than 580 percent minutes or not greater than 570 percent minutes or even not greater than 560 percent minutes. Still, in at least one non-limiting embodiment, the abrasive particles can have a primary deformation amplitude and time multiplier of at least 100 percent minutes, such as at least 150 percent minutes or even at least 200 percent minutes. It will be appreciated that the abrasive particles can have a primary deformation amplitude and time multiplier within a range including any of the minimum and maximum values noted above.
In still another aspect, the abrasive particles of the embodiments herein may have a certain secondary deformation characteristic rate, which may be an indication of the likelihood of a particle to plastically deform over a long period of time, wherein a secondary deformation characteristic rate may facilitate improved performance. According to one embodiment, the abrasive particles can have a secondary deformation characteristic rate of not greater than 6×10−3 percent/minute as calculated by the formula [(L−L0)/L0]*100/min, such as not greater than 4×10−3 percent/minute or not greater than 2×10−3 percent/minute or not greater than 1×10−3 percent/minute or not greater than 8×10−4 percent/minute or not greater than 5×10−4 percent/minute or not greater than 1×10−4 percent/minute or not greater than 5×10−5 percent/minute or not greater than 1×10−5 percent/minute or not greater than 5×10−6 percent/minute or not greater than 1×10−6 percent/minute or not greater than 5×10−7 percent/minute or not greater than 1×10−7 percent/minute or not greater than 5×10−8 percent/minute. Still, in one non-limiting embodiment, the abrasive particles can have a secondary deformation characteristic rate of at least 1×10−12 percent/minute or at least 1×10−1° percent/minute. It will be appreciated that the abrasive particles can have a secondary deformation characteristic rate within a range including any of the minimum and maximum values noted above.
The abrasive particles of the embodiments herein may include one or more microstructural characteristics and/or deformation characteristics that may facilitate improved performance. For example, the abrasive particles can have one or more microstructural characteristics, including for example, an average crystal size of not greater than 6 microns or a hardness of at least 20 GPa. Moreover, it will be appreciated that the abrasive particles of the embodiments herein can have a combination of more than one particular microstructural feature, including for example, an average crystal size of not greater than 6 microns and a hardness of at least 20 GPa. Moreover, the abrasive particles may have one or more certain deformation characteristics, including any of the deformation characteristics as described herein. In one particular embodiment, the abrasive particles can include at least one deformation characteristic including a primary deformation amplitude of not greater than 30 percent, a primary deformation time of not greater than 280 minutes or a secondary deformation characteristic rate of not greater than 6×10−3 percent/minute. Still, it will be appreciated that at least one embodiment, can include a combination of more than one deformation characteristic, including but not limited to, a primary deformation amplitude of not greater than 30 percent, a primary deformation time of not greater than 280 minutes, and a secondary deformation characteristic rate of not greater than 6×10−3 percent/minute.
The abrasive particles of the embodiments herein may be incorporated into fixed abrasive articles, including but not limited to bonded abrasives, coated abrasives, non-woven abrasives, abrasive brushes, and the like. The abrasive particles may also be utilized as free abrasives, such as in slurries.
According to one embodiment, the substrate 701 can include an organic material, inorganic material, and a combination thereof. In certain instances, the substrate 701 can include a woven material. However, the substrate 701 may be made of a non-woven material. Particularly suitable substrate materials can include organic materials, including polymers, and particularly, polyester, polyurethane, polypropylene, polyimides such as KAPTON from DuPont, paper. Some suitable inorganic materials can include metals, metal alloys, and particularly, foils of copper, aluminum, steel, and a combination thereof.
The make coat 703 can be applied to the surface of the substrate 701 in a single process, or alternatively, the abrasive particulate materials 705, 706, 707 can be combined with a make coat 703 material and the combination of the make coat 703 and abrasive particulate materials 705-707 can be applied as a mixture to the surface of the substrate 701. In certain instances, controlled deposition or placement of the abrasive particles in the make coat may be better suited by separating the processes of applying the make coat 703 from the deposition of the abrasive particulate materials 705-707 in the make coat 703. Still, it is contemplated that such processes may be combined. Suitable materials of the make coat 703 can include organic materials, particularly polymeric materials, including for example, polyesters, epoxy resins, polyurethanes, polyamides, polyacrylates, polymethacrylates, polyvinylchlorides, polyethylene, polysiloxane, silicones, cellulose acetates, nitrocellulose, natural rubber, starch, shellac, and mixtures thereof. In one embodiment, the make coat 703 can include a polyester resin. The coated substrate can then be heated in order to cure the resin and the abrasive particulate material to the substrate. In general, the coated substrate 701 can be heated to a temperature of between about 100° C. to less than about 250° C. during this curing process.
The abrasive particulate materials 705, 706, and 707 can include different types of shaped abrasive particles according to embodiments herein. The different types of shaped abrasive particles can differ from each other in composition, two-dimensional shape, three-dimensional shape, size, and a combination thereof as described in the embodiments herein. As illustrated, the coated abrasive 700 can include a first type of shaped abrasive particle 705 having a generally triangular two-dimensional shape and a second type of shaped abrasive particle 706 having a quadrilateral two-dimensional shape. The coated abrasive 700 can include different amounts of the first type and second type of shaped abrasive particles 705 and 706. It will be appreciated that the coated abrasive may not necessarily include different types of shaped abrasive particles, and can consist essentially of a single type of shaped abrasive particle. As will be appreciated, the shaped abrasive particles of the embodiments herein can be incorporated into various fixed abrasives (e.g., bonded abrasives, coated abrasive, non-woven abrasives, thin wheels, cut-off wheels, reinforced abrasive articles, and the like), including in the form of blends, which may include different types of shaped abrasive particles, shaped abrasive particles with diluent particles, and the like. Moreover, according to certain embodiments, batch of particulate material may be incorporated into the fixed abrasive article in a predetermined orientation, wherein each of the shaped abrasive particles can have a predetermined orientation relative to each other and relative to a portion of the abrasive article (e.g., the backing of a coated abrasive).
The abrasive particles 707 can be diluent particles different than the first and second types of shaped abrasive particles 705 and 706. For example, the diluent particles can differ from the first and second types of shaped abrasive particles 705 and 706 in composition, two-dimensional shape, three-dimensional shape, size, and a combination thereof. For example, the abrasive particles 707 can represent conventional, crushed abrasive grit having random shapes. The abrasive particles 707 may have a median particle size less than the median particle size of the first and second types of shaped abrasive particles 705 and 706.
After sufficiently forming the make coat 503 with the abrasive particulate materials 705, 706, 707 contained therein, the size coat 704 can be formed to overlie and bond the abrasive particulate material 705 in place. The size coat 704 can include an organic material, may be made essentially of a polymeric material, and notably, can use polyesters, epoxy resins, polyurethanes, polyamides, polyacrylates, polymethacrylates, poly vinyl chlorides, polyethylene, polysiloxane, silicones, cellulose acetates, nitrocellulose, natural rubber, starch, shellac, and mixtures thereof.
The abrasive particulate material 802 of the bonded abrasive 800 can include different types of shaped abrasive particles 803, 804, 805, and 806, which can have any of the features of different types of shaped abrasive particles as described in the embodiments herein. Notably, the different types of shaped abrasive particles 803, 804, 805, and 806 can differ from each other in composition, two-dimensional shape, three-dimensional shape, size, and a combination thereof as described in the embodiments herein.
The bonded abrasive 800 can include a type of abrasive particulate material 807 representing diluent abrasive particles, which can differ from the different types of shaped abrasive particles 803, 804, 805, and 806 in composition, two-dimensional shape, three-dimensional shape, size, and a combination thereof.
The porosity 808 of the bonded abrasive 800 can be open porosity, closed porosity, and a combination thereof. The porosity 808 may be present in a majority amount (vol %) based on the total volume of the body of the bonded abrasive 800. Alternatively, the porosity 808 can be present in a minor amount (vol %) based on the total volume of the body of the bonded abrasive 800. The bond material 801 may be present in a majority amount (vol %) based on the total volume of the body of the bonded abrasive 800. Alternatively, the bond material 801 can be present in a minor amount (vol %) based on the total volume of the body of the bonded abrasive 800. Additionally, abrasive particulate material 802 can be present in a majority amount (vol %) based on the total volume of the body of the bonded abrasive 800. Alternatively, the abrasive particulate material 802 can be present in a minor amount (vol %) based on the total volume of the body of the bonded abrasive 800.
At least one of the abrasive particles in accordance with an embodiment herein can have a 1000° C. Vickers Hot Hardness, as measured according to the hot hardness test described below, of at least 12.0 GPa or at least 12.2 GPa or at least 12.5 GPa or at least 12.7 GPa or at least 13.0 GPa or at least 13.3 GPa or at least 13.5 GPa. At least one of the abrasive particles in accordance with another embodiment herein can have a 1000° C. Vickers Hot Hardness of no greater than 20 GPa, such as no greater than 18 GPa or no greater than 15 GPa. It will be appreciated that at least one abrasive particle can have a 1000° C. Vickers Hot Hardness within a range including any of the minimum and maximum values noted above. It will further be noted that any of the foregoing values related to 1000° C. Vickers Hot Hardness can be an average value for a batch of abrasive particles or average value for a statistically relevant sample size from a batch of abrasive particles.
In yet another embodiment, at least one abrasive particle can have a 800° C. Vickers Hot Hardness of at least 14.5 GPa or at least 15.0 GPa or at least 15.5 GPa or at least 16.0 GPa or at least 16.5 GPa or at least 17.0 GPa or at least 17.5 GPa or at least 18.0 GPa. In yet another embodiment, at least one of the abrasive particles can have 800° C. Vickers Hot Hardness of no greater than 25 GPa or no greater than 23 GPa or no greater than 21 GPa or no greater than 20 GPa. It will be appreciated that at least one abrasive particle can have a 800° C. Vickers Hot Hardness within a range including any of the minimum and maximum values noted above. It will further be noted that any of the foregoing values related to 800° C. Vickers Hot Hardness can be an average value for a batch of abrasive particles or average value for a statistically relevant sample size from a batch of abrasive particles.
In yet a further embodiment, at least one abrasive particle can have a 600° C. Vickers Hot Hardness of at least 19 GPa or at least 19.5 GPa or at least 20.0 GPa or at least 20.5 GPa or at least 21.0 GPa or at least 21.5 GPa or at least 22.0 GPa. In another embodiment, at least one of the abrasive particles can have a 600° C. Vickers Hot hardness of no greater than 27.0 GPa or no greater than 25.0 GPa or no greater than 23.0 GPa. It will be appreciated that at least one abrasive particle can have a 600° C. Vickers Hot Hardness within a range including any of the minimum and maximum values noted above. It will further be noted that any of the foregoing values related to 600° C. Vickers Hot Hardness can be an average value for a batch of abrasive particles or average value for a statistically relevant sample size from a batch of abrasive particles.
In another embodiment, at least one abrasive particle can have a 400° C. Vickers Hot Hardness of at least 19.0 GPa or at least 19.5 GPa or at least 20.0 GPa or at least 20.5 GPa or at least 21.0 GPa or at least 21.5 GPa or at least 22.0 GPa or at least 22.5 GPa or at least 23.0 GPa. In another embodiment, at least one of the abrasive particles can have a 400° C. Vickers Hot Hardness of no greater than 35.0 GPa or no greater than 31.0 GPa or no greater than 27.0 GPa or no greater than 24.0 GPa. It will be appreciated that at least one abrasive particle can have a 400° C. Vickers Hot Hardness within a range including any of the minimum and maximum values noted above. It will further be noted that any of the foregoing values related to 400° C. Vickers Hot Hardness can be an average value for a batch of abrasive particles or average value for a statistically relevant sample size from a batch of abrasive particles. It is noted that unless indicated otherwise such as with the specification of Vickers Hot Hardness, hardness measurements described herein pertain to room temperature hardness.
Five samples were obtained or prepare and tested for comparison to evaluate the high temperature creep performance and abrasive performance. A first comparative sample (CS1) was a conventional shaped abrasive particle commercially available in 3M984F coated abrasive products from 3M Corporation.
A second comparative sample (CS2) was a conventional shaped abrasive particle commercially available in 3M994F coated abrasive products from 3M. The shaped abrasive particle of this sample had a shape similar to that as illustrated in
Three other individual samples (S1, S2, and S3) were prepared from a gel including 41.5 wt % boehmite commercially available as Reflux Catapal B and seeded with 1% alpha alumina seeds and dopants in the weight percentages as provided in Table 1. The mixture also included 55 wt % water and 2.5 wt % nitric acid. The mixture was extruded into triangular shaped openings in a production tool, wherein the triangular shaped openings had a length of 2.77 mm, a width of 2.4 mm and a depth (height) of 0.53 mm. The production tool was made of metal. The surfaces of the openings in the production tool were coated with a lubricant of olive oil to facilitate removal of the precursor shaped abrasive particles from the production tool. The mixture was dried in the openings at approximately 50° C. for 10 minutes. The mixture was then removed from the openings of the production tool and sintered at the temperatures provided in Table 1 for approximately 10 minutes to obtain the average crystal size and density as also reported in Table 1. SEM micrograph images of each of the samples S1-S3 are provided in
Twelve samples are obtained or to be prepared and a portion of which are tested for comparison to evaluate hot hardness performance and abrasive performance. A first comparative sample is CS1 described above in Example 1. CS 1 is a conventional shaped abrasive particle commercially available in 3M984F coated abrasive products from 3M Corporation.
A third comparative sample (CS3) is a pure seeded gel shaped abrasive particle. The shaped abrasive particle has a shape similar to that illustrated in
Ten other individual samples (S4, S5, S6, S7, S8, S9, S10, S11, S12) are prepared from a gel including 48.3 wt % boehmite commercially available as Reflux Catapal B and seeded with 0.35 wt % alpha alumina seeds and dopants in the weight percentages as provided in Table 2. The samples are doped by impregnation with yttrium nitrate hexahydrate and magnesium nitrate hexahydrate as doping precursors. The mixtures also include 50 wt % water and 1.3 wt % nitric acid. The mixture is extruded into triangular shaped openings in a production tool, wherein the triangular shaped openings have a length of 2.77 mm, a width of 2.4 mm, and a depth (height) of 0.51 mm. The production tool is made of metal. The opening surfaces of the openings in the production tool are coated with a lubricant of olive oil to facilitate removal of the precursor shaped abrasive particles from the production tool. The mixture is dried in the openings at approximately 50° C. for 10 minutes. The mixture is then removed from the openings of the production tool and sintered at temperatures between 1300° C. and 1400° C. The samples are then coated onto an abrasive belt with a number of cutting points per square centimeter in a range of 40 to 45.
Hot hardness is tested using a Nikon QM hot hardness tester. The equipment is capable of testing samples at temperatures up to 1000° C. The sample is mounted in a heating chamber which is subsequently evacuated. During testing, the vacuum level is monitored and the temperature of the indenter and sample is measured by thermocouples. Testing is performed using a diamond Vickers indenter at temperatures in 200° C. intervals from 400° C. to 1000° C. The test cycle is approximately 45 minutes with hold segments from 3-4 minutes. During the hold segment, three to five indentations are performed. The indentation load is 375 g.
The samples have polished flat and parallel sides and are mounted on a 5×5×10 mm alumina block using high temperature cement. Each sample holder has two samples mounted thereon.
Hardness of the samples is calculated from the measured indents according to the Vickers method for ceramics (ASTM C1327).
One or more of Samples S4 to S13 may be distinct based upon hot hardness, creep, grinding performance or a combination thereof.
Many different aspects and embodiments are possible. Some of those aspects and embodiments are described herein. After reading this specification, skilled artisans will appreciate that those aspects and embodiments are only illustrative and do not limit the scope of the present invention. Embodiments may be in accordance with any one or more of the embodiments as listed below.
An abrasive particle comprising:
a body having at least one microstructural characteristic including:
and wherein the body further comprises at least one deformation characteristic including:
An abrasive particle comprising a body having an average crystal size of not greater than 6 microns and a primary deformation amplitude of not greater than 30 percent.
An abrasive particle comprising a body having a hardness of at least 20 GPa and a primary deformation amplitude of not greater than 30 percent.
An abrasive particle comprising shaped abrasive particle including a body having a primary deformation amplitude and time multiplier of not greater than 700 percent minutes.
An abrasive particle comprising a body including a first dopant comprising magnesium and a second dopant comprising at least one element of the group consisting of yttrium, lanthanum, a rare-earth element, wherein the body comprises a greater content of the second dopant compared to a content of the first dopant, and a primary deformation amplitude of not greater than 9 percent.
An abrasive particle comprising a body including a first dopant comprising magnesium and a grain boundary phase comprising at least one of yttrium, lanthanum, and a rare-earth element combined with aluminum and oxygen.
The abrasive particle of any one of Embodiments 1, 2, 3, 5, and 6, wherein the body comprises:
at least one microstructural characteristic selected from the group consisting of:
and wherein the body further comprises at least one deformation characteristic selected from the group consisting of:
The abrasive particle of any one of Embodiments 1, 2, 3, 5, and 6, wherein the body comprises:
microstructural characteristics including:
wherein the body further comprises deformation characteristics including:
The abrasive particle of any one of Embodiments 1, 2, 3, 5, and 6, wherein the abrasive particle is a shaped abrasive particle.
The shaped abrasive particle of any one of Embodiments 4 and 9, wherein the shaped abrasive particle includes a body having a two-dimensional shape selected from the group consisting of polygons, ellipsoids, numerals, Greek alphabet letters, Latin alphabet letters, Russian alphabet characters, complex shapes, and a combination thereof.
The shaped abrasive particle of any one of Embodiments 4 and 9, wherein the shaped abrasive particle includes a body having a two-dimensional polygonal shape selected from the group consisting of a triangle, a rectangle, a quadrilateral, a pentagon, a hexagon, a heptagon, an octagon, a nonagon, a decagon, and a combination thereof.
The shaped abrasive particle of any one of Embodiments 4 and 9, wherein the shaped abrasive particle includes a body having a Shape Index of at least 0.01 and not greater than 0.49.
The shaped abrasive particle of any one of Embodiments 4 and 9, wherein the shaped abrasive particle includes a body having a Shape Index of greater than 0.52 and not greater than 0.99.
The shaped abrasive particle of any one of Embodiments 4 and 9, wherein the shaped abrasive particle includes a body having a perimeter defined by at least one linear section and at least one arcuate section.
The shaped abrasive particle of any one of Embodiments 4 and 9, wherein the shaped abrasive particle includes a body having a central region and at least three arms extending from the central region.
The shaped abrasive particle of any one of Embodiments 4 and 9, wherein the arms comprise tips including external corners defined by a joint between two linear sections and at least one arcuate portion extending between two external corners.
The shaped abrasive particle of any one of Embodiments 4 and 9, wherein the shaped abrasive particle includes a two-dimensional shape having perimeter defined by at least three discrete linear portions and three discrete arcuate portions, wherein each of the three discrete linear portions are separated from each other by at least one of the discrete arcuate portions.
The abrasive particle of any one of Embodiments 3, 4, 5, and 6, wherein the body comprises an average crystal size of not greater than 6 microns.
The abrasive particle of any one of Embodiments 1, 2, and 18, wherein the body comprises an average crystal size of not greater than 5 microns or not greater than 4 microns or not greater than 3.5 microns or not greater than 3 microns or not greater than 2.5 microns or not greater than 2 microns or not greater than 1.5 microns or not greater than 1 micron or not greater than 0.8 microns or not greater than 0.6 microns.
The abrasive particle of any one of Embodiments 1, 2, and 18, wherein the body comprises an average crystal size of at least 0.01 microns.
The abrasive particle of any one of Embodiments 2, 4, 5, and 6, wherein the body comprises a hardness of at least 20 GPa.
The abrasive particle of any one of Embodiments 1, 3, and 21, wherein the body comprises a hardness of at least 20.5 GPa or at least 21 GPa or at least 21.5 GPa or at least 22 GPa.
The abrasive particle of any one of Embodiments 1, 3, and 21, wherein the body comprises a hardness of not greater than 40 GPa or not greater than 30 GPa or not greater than 28 GPa.
The abrasive particle of any one of Embodiments 4, 5, and 6, wherein the body comprises a primary deformation amplitude of not greater than 30 percent.
The abrasive particle of any one of Embodiments 1, 2, 3, and 24, wherein the body comprises a primary deformation amplitude of not greater than 25 percent or not greater than 20 percent or not greater than 18 percent or not greater than 16 percent or not greater than 14 percent or not greater than 13 percent or not greater than 12 percent or not greater than 11 percent or not greater than 10 percent or not greater than 9 percent or not greater than 8 percent or not greater than 7 percent or not greater than 6 percent or not greater than 5 percent.
The abrasive particle of any one of Embodiments 1, 2, 3, and 24, wherein the body comprises a primary deformation amplitude of at least 0.01 percent or at least 0.1 percent.
The abrasive particle of any one of Embodiments 2, 3, 4, 5, and 6, wherein the body comprises a primary deformation time of not greater than 280 minutes.
The abrasive particle of any one of Embodiments 1 and 27, wherein the body comprises a primary deformation time of not greater than 250 minutes or not greater than 230 minutes or not greater than 200 minutes or not greater than 180 minutes or not greater than 160 minutes or not greater than 150 minutes.
The abrasive particle of any one of Embodiments 1 and 27, wherein the body comprises a primary deformation time of at least 100 minutes or at least 110 minutes or at least 120 minutes or at least 130 minutes or at least 140 minutes.
The abrasive particle of any one of Embodiments 1, 2, 3, 5, and 6, wherein the body comprises a primary deformation amplitude and time multiplier of not greater than 700 percent minutes.
The abrasive particle of any one of Embodiments 4 and 30, wherein the body comprises a primary deformation amplitude and time multiplier of not greater than 690 percent minutesor not greater than 680 percent minutes or not greater than 670 percent minutes or not greater than 660 percent minutes or not greater than 650 percent minutes or not greater than 640 percent minutes or not greater than 630 percent minutes or not greater than 620 percent minutes or not greater than 610 percent minutes or not greater than 600 percent minutes or not greater than 590 percent minutes or not greater than 580 percent minutes or not greater than 570 percent minutes or even not greater than 560 percent minutes.
The abrasive particle of any one of Embodiments 4 and 30, wherein the body comprises a primary deformation amplitude and time multiplier of at least 100 percent minutes or at least 150 percent minutes or at least 200 percent minutes.
The abrasive particle of any one of Embodiments 2, 3, 4, 5, and 6, wherein the body comprises a secondary deformation characteristic rate of not greater than 6×10−3percent/minute.
The abrasive particle of any one of Embodiments 1 and 33, wherein the body comprises a secondary deformation characteristic rate of not greater than 6×10−3 percent/minute or not greater than 4×10−3 percent/minute or not greater than 2×10−3 percent/minute or not greater than 1×10−3 percent/minute or not greater than 8×10−4 percent/minute or not greater than 5×10−4 percent/minute or not greater than 1×10−4 percent/minute or not greater than 5×10−5 percent/minute or not greater than 1×10−5 percent/minute or not greater than 5×10−6 percent/minute or not greater than 1×10−6 percent/minute or not greater than 5×10−7 percent/minute or not greater than 1×10−7 percent/minute or not greater than 5×10−8 percent/minute.
The abrasive particle of any one of Embodiments 1 and 33, wherein the body comprises a secondary deformation characteristic rate of at least 1×10−12 percent/minute or at least 1×10−1° percent/minute.
The abrasive particle of any one of Embodiments 1, 2, 3, 4, 5, and 6, wherein the body comprises a density of at least 95% theoretical density or at least 96% theoretical density or at least 97% theoretical density or at least 98% theoretical density or at least 99% theoretical density.
The abrasive particle of any one of Embodiments 1, 2, 3, 4, 5, and 6, wherein the body comprises alumina.
The abrasive particle of any one of Embodiments 1, 2, 3, 4, 5, and 6, wherein the body includes a majority content of alumina, wherein the body includes at least 80% alumina or at least 90% alumina or at least 91% alumina or at least 92% alumina or at least 93% alumina or at least 94% alumina or at least 95% alumina or at least 96% alumina or at least 97% alumina.
The abrasive particle of any one of Embodiments 1, 2, 3, and 4, wherein the body comprises a first dopant comprising magnesium.
The abrasive particle of any one of Embodiments 5, 6, and 39, wherein the first dopant comprises a majority content of magnesium and oxygen.
The abrasive particle of any one of Embodiments 5, 6, and 39, wherein the first dopant consists essentially of magnesium and oxygen.
The abrasive particle of any one of Embodiments 5, 6, and 39, wherein the body comprises at least 0.1 wt % of the first dopant for the total weight of the body or at least 0.15 wt % or at least 0.2 wt % or at least 0.3 wt % or at least 0.4 wt % or at least 0.5 wt % or at least 0.6 wt % or at least 0.7 wt % or at least 0.8 wt % or at least 0.9 wt %.
The abrasive particle of any one of Embodiments 5, 6, and 39, wherein the body comprises not greater than 4.5 wt % of the first dopant for the total weight of the body or not greater than 4 wt % or not greater than 3 wt % or not greater than 2.5 wt % or not greater than 2.2 wt % or not greater than 2 wt % or not greater than 1.9 wt % or not greater than 1.8 wt % or not greater than 1.7 wt % or not greater than 1.6 wt % or not greater than 1.5 wt % or not greater than 1.4 wt % or not greater than 1.3 wt % or not greater than 1.2 wt %.
The abrasive particle of any one of Embodiments 1, 2, 3, and 4, wherein the body comprises a first dopant and a second dopant different than the first dopant.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the second dopant comprises at least one element from the group consisting of yttrium, lanthanum, a rare-earth element, and a combination thereof.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the first dopant is present in a first grain boundary phase and the second dopant is present in a second grain boundary phase, and wherein the first and second grain boundary phases are substantially homogeneous throughout the body.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the first and second dopants are substantially homogeneously dispersed throughout the entire volume of the body.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein at least one of the first and second dopants are preferentially distributed in a higher concentration near the exterior surfaces of the body compared to the interior region surrounding a volumetric midpoint of the body.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the second dopant comprises a majority content of yttrium and oxygen.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the second dopant consists essentially of yttrium and oxygen.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the body comprises at least 0.1 wt % of the second dopant for the total weight of the body or at least 0.2 wt % or at least 0.4 wt % or at least 0.6 wt % or at least 0.8 wt % or at least 1 wt % or at least 1.1 wt % or at least 1.2 wt % or at least 1.3 wt % or at least 1.4 wt % or at least 1.5 wt % or at least 1.6 wt % or at least 1.7 wt % or at least 1.8 wt % or at least 1.9 wt % or at least 2 wt %.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the body comprises not greater than 10 wt % of the second dopant for the total weight of the body or not greater than 9 wt % or not greater than 8 wt % or not greater than 7 wt % or not greater than 6 wt % or not greater than 5 wt % or not greater than 4 wt % or not greater than 3.5 wt % or not greater than 3.2 wt % or not greater than 3 wt % or not greater than 2.9 wt % or not greater than 2.8 wt % or not greater than 2.7 wt % or not greater than 2.6 wt % or not greater than 2.5 wt % or not greater than 2.4 wt % or not greater than 2.3 wt % or not greater than 2.2 wt % or not greater than 2.1 wt %.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the body comprises a dopant ratio value (D1/D2) of at least 1, wherein D1 represents the weight percent of the first dopant in the body and D2 represent the weight percent of the second dopant in the body, wherein the dopant ratio value is greater than 1 or at least 1.1 or at least 1.2 or at least 1.3 or at least 1.4 or at least 1.5 or at least 1.6 or at least 1.7 or at least 1.8 or at least 1.9 or at least 2.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the body comprises a dopant ratio value (D1/D2) of not greater than 10, wherein D1 represents the weight percent of the first dopant in the body and D2 represent the weight percent of the second dopant in the body, wherein the dopant ratio value is not greater than 9 or not greater than 8 or not greater than 7 or not greater than 6 or not greater than 5 or not greater than 4 or not greater than 3.5 or not greater than 3 or not greater than 2.8 or not greater than 2.5.
The abrasive particle of any one of Embodiments 5, 6, and 44, wherein the body comprises a dopant ratio value (D2/D1) of at least 1, wherein D1 represents the weight percent of the first dopant in the body and D2 represent the weight percent of the second dopant in the body, wherein the dopant ratio value is greater than 1 or at least 1.1 or at least 1.2 or at least 1.3 or at least 1.4 or at least 1.5 or at least 1.6 or at least 1.7 or at least 1.8 or at least 1.9 or at least 2.
The abrasive particle of any one of Embodiments 5, 6, and 42, wherein the body comprises a dopant ratio value (D2/D1) of not greater than 10, wherein D1 represents the weight percent of the first dopant in the body and D2 represent the weight percent of the second dopant in the body, wherein the dopant ratio value is not greater than 9 or not greater than 8 or not greater than 7 or not greater than 6 or not greater than 5 or not greater than 4 or not greater than 3.5 or not greater than 3 or not greater than 2.8 or not greater than 2.5.
The abrasive particle of any one of Embodiments 1, 2, 3, 4, 5, and 6, wherein the body is essentially free of zirconium, cobalt, iron, calcium, carbides, nitrides, silicon, lithium, sodium, potassium, strontium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, niobium, molybdenum, ruthenium, palladium, hafnium, tantalum, lanthanum, cerium, neodymium, scandium, zinc, and a combination thereof.
The abrasive particle of any one of Embodiments 1, 2, 3, 4, 5, and 6, wherein the body is essentially free of a rare earth metal selected from praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, cerium, dysprosium, and erbium.
The abrasive particle of any one of Embodiments 1, 2, 3, 4, 5, and 6, wherein the body consists essentially of alpha alumina, magnesium-containing oxides, and yttrium-containing oxides, wherein the content of alpha alumina is greater than the magnesium-containing oxides, and the content of the magnesium-containing oxides is greater than the content of yttrium-containing oxides.
The abrasive particle of any one of Embodiments 1, 2, 3, 4, 5, and 6, wherein the body further comprises zirconium, lanthanum, strontium, lutetium, neodymium, and a combination thereof.
The abrasive particle of any one of Embodiments 1, 2, 3, 4, and 5, wherein the body includes a grain boundary phase comprising yttrium, aluminum, and oxygen.
The abrasive particle of any one of Embodiments 6 and 61, wherein the grain boundary phase is an oxide compound including yttrium and aluminum.
The abrasive particle of any one of Embodiments 6 and 61, wherein the grain boundary phase is a yttrium aluminate compound.
The abrasive particle of any one of Embodiments 6 and 61, wherein the grain boundary phase comprises a polycrystalline material bonded to the surrounding grains.
The abrasive particle of any one of Embodiments 1, 2, 3, 4, 5, and 6, further comprising a fixed abrasive article including the abrasive particle.
The abrasive particle of Embodiment 65, wherein the fixed abrasive article is selected from the group consisting of a coated abrasive, a bonded abrasive, a non-woven abrasive, and a combination thereof.
The abrasive particle of any one of the preceding Embodiments, wherein the abrasive particle has a 1000° C. Vickers Hot Hardness of at least 12.0 GPa, at least 12.2 GPa, at least 12.5 GPa, at least 12.7 GPa, at least 13.0 GPa, at least 13.3 GPa, or at least 13.5 GPa.
The abrasive particle of any one of the preceding Embodiments, wherein the abrasive particle has a 1000° C. Vickers Hot Hardness of no greater than 20 GPa, no greater than 18 GPa, or no greater than 15 GPa.
The abrasive particle of any one of the preceding Embodiments, wherein the abrasive particle has a 800° C. Vickers Hot Hardness of at least 14.5 GPa, at least 15.0 GPa, at least 15.5 GPa, at least 16.0 GPa, at least 16.5 GPa, at least 17.0 GPa, at least 17.5 GPa, or at least 18.0 GPa.
The abrasive particle of any one of the preceding Embodiments, wherein the abrasive particle has a 800° C. Vickers Hot Hardness of no greater than 25 GPa, no greater than 23 GPa, no greater than 21 GPa, or no greater than 20 GPa.
The abrasive particle of any one of the preceding Embodiments, wherein the abrasive particle has a 600° C. Vickers Hot Hardness of at least 19 GPa, at least 19.5 GPa, at least 20.0 GPa, at least 20.5 GPa, at least 21.0 GPa, at least 21.5 GPa, or at least 22.0 GPa.
The abrasive particle of any one of the preceding Embodiments, wherein the abrasive particle has a 600° C. Vickers Hot hardness of no greater than 27.0 GPa, no greater than 25.0 GPa, or no greater than 23.0 GPa.
The abrasive particle of any one of the preceding Embodiments, wherein the abrasive particle has a 400° C. Vickers Hot Hardness of at least 19.0 GPa, at least 19.5 GPa, at least 20.0 GPa, at least 20.5 GPa, at least 21.0 GPa, at least 21.5 GPa, at least 22.0 GPa, at least 22.5 GPa, or at least 23.0 GPa.
The abrasive particle of any one of the preceding Embodiments, wherein the abrasive particle has a 400° C. Vickers Hot Hardness of no greater than 35.0 GPa, no greater than 31.0 GPa, no greater than 27.0 GPa, or no greater than 24.0 GPa.
A method of making an abrasive particle including forming a mixture including an alpha alumina precursor material a first dopant comprising magnesium and a second dopant comprising yttrium, wherein the content of the second dopant is greater than the first dopant, and sintering the mixture to form an abrasive particle.
The method of Embodiment 75, wherein the abrasive particle comprises an abrasive particle in accordance with any one of Embodiments 1-74.
The method of any one of Embodiments 75 and 76, wherein the method further comprises attaching the abrasive particle to an abrasive article.
The method of any one of Embodiments 75-77, further comprising drying mixture prior to sintering the mixture.
The method of any one of Embodiments 75-78, wherein the mixture is introduced to a mold cavity for shaping.
The method of Embodiment 79, wherein the mixture undergoes drying while in the mold cavity.
The method of any one of Embodiments 79 and 80, wherein a mold release agent is applied to the mixture while the mixture is in the mold cavity.
The method of any one of Embodiments 79-81, wherein the mixture is released from the mold cavity to form a precursor shaped abrasive particle.
The method of any one of Embodiments 75-82, wherein at least one of the first and second dopants is applied by spraying, dipping, depositing, impregnating, transferring, punching, cutting, pressing, crushing, or any combination thereof.
The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.
The Abstract of the Disclosure is provided to comply with Patent Law and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all features of any of the disclosed embodiments. Thus, the following claims are incorporated into the Detailed Description, with each claim standing on its own as defining separately claimed subject matter.
The present application claims priority from U.S. Provisional Patent Application No. 62/165,028, filed May 21, 2015, entitled “ABRASIVE PARTICLES AND METHOD OF FORMING SAME,” naming inventors David F. Louapre and Eric Moch, and said provisional application is incorporated by reference herein in its entirety for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62165028 | May 2015 | US |
