Patent Application
20130081334
The present disclosure generally relates to bonded abrasives, and more particularly to forming bonded abrasive articles through uniaxial hot pressing.
Uniaxial pressing has typically been restricted to bodies having uniform cross-sections, as non-uniform cross-sections may react unpredictably to the application of pressure. Pressure applied to a body having a non-uniform cross-section may result in a distortion of shape and/or non-uniform density. Uniaxial hot pressing has also typically been restricted to bodies having uniform compositions, in order to avoid differing amounts of shrinkage resulting from variable coefficients of thermal expansion. Differing amounts of shrinkage can result in regions of partially undensified material or regions of increased stress.
U.S. Pat. No. 4,153,666 discloses hot pressing a preformed shape which deforms orderly to a final shape in a mold against preformed parts having surfaces exactly mating with the surfaces of the preform. The preformed parts are formed of a powdered composition having the same compaction ratio as the preform and a coefficient of thermal expansion substantially equal to that of the preform.
U.S. Pat. Nos. 6,306,325 and 6,508,964 disclose hot pressing ceramic bodies in a mold, wherein the ceramic bodies are homogeneous in composition.
U.S. Pat. No. 3,467,745 discloses hot pressing refractory carbide bodies with shaped cavities by incorporating a water-reactive carbide in amounts and at locations corresponding to the locations and size of the cavities desired in the final body. The water-reactive carbide may be leached out with water following pressing.
U.S. Pat. No. 5,250,130 discloses hot pressing a green body with a non-uniform compositional cross-section relative to the axial direction by laminating auxiliary material with the green body in the axial direction to achieve a uniform shrinkage that is substantially equal across the laminate. The auxiliary material is delaminated from the body after hot pressing.
In a particular embodiment, a method includes uniaxially hot pressing a preform that includes abrasive particles in a bonding material to form a bonded abrasive body.
In another embodiment, a method includes uniaxially hot pressing a preform that includes abrasive particles to form a body having a relief extending from a plane on the body that is parallel to an axis of pressing.
In another embodiment, a method of forming a bonded abrasive body includes forming a green body comprising abrasive particles and a bonding material. The method further includes placing the green body in a mold and uniaxially hot pressing the green body to form the bonded abrasive body.
In another embodiment, a method includes forming a mixture of abrasive particles and bonding material, forming the mixture into a green body, and placing the green body in a mold. The method further includes uniaxially hot pressing the mold to form a bonded abrasive body with a near net shape that is asymmetric around a pressing axis.
In another embodiment, a method includes uniaxially hot pressing a green body preform to form a composite body. Pressing includes liquid phase sintering, and during pressing the geometry of the preform is substantially altered.
The present disclosure may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings.
a includes an illustration of a preform in accordance with an embodiment disclosed herein.
b includes a top view illustration of the exemplary preform of
a includes an illustration of a particular embodiment of a single mold for making an abrasive tool.
b includes an illustration of a particular embodiment of a mold for use in a mold pack for making an abrasive tool.
a includes an illustration of a particular embodiment of an abrasive tool with a relief.
b includes an illustration of a plane of the exemplary abrasive tool of
c includes a side-view illustration of the exemplary abrasive tool of
a, 10b, and 10c include illustrations of multiple exemplary embodiments of abrasive tools with alternative relief orientations.
The use of the same reference symbols in different drawings indicates similar or identical items.
According to one aspect of the present disclosure, a method is disclosed that includes uniaxially hot pressing a preform that includes abrasive particles in a bonding material to form a bonded abrasive body. With uniaxial hot pressing, a force is applied to a body in substantially one direction or along a single axis while heat is applied to the body such that the geometric shape of the body is substantially changed. The axis along which force is applied during uniaxial hot pressing is referred to herein as the axis of pressing. Thus, according to one aspect of the present disclosure, a bonded abrasive body may be formed by hot pressing a preform (e.g., a green or unsintered body) along a single axis (i.e., the axis of pressing).
The bonding material can include an inorganic material. In an embodiment, the major content (e.g., greater than 50% by volume, weight, or molar percentage) of the bonding material may include an inorganic material. For example, the bonding material may be a ceramic, such as a vitreous material.
In another example, the bonding material may include a metal or a metal alloy. For example, the bonding material can include one or more transition metal elements. Suitable transition metal elements can include, but are not limited to, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, tin, zirconium, silver, molybdenum, tantalum, tungsten, or a combination thereof. Specifically, the bonding material can include one or more transition metal elements selected from the group including cobalt, iron, copper, and nickel. In a particular aspect, the bonding material can include an electrolytic iron powder, pre-alloyed bronze, a nickel base alloy, or a combination thereof. In an exemplary, non-limiting embodiment, the bonding material can include 40 wt % electrolytic iron powder (−315 mesh), 48 wt % water atomized pre-alloyed bronze 90/10 (−200 mesh), and 12 wt % nickel base alloy (53-75 μm).
In another example, the bonding material can include an organic material. In an embodiment, the major content (e.g., greater than about 50% by volume, weight, or molar percentage) of the bonding material may include an organic material. Illustrative organic materials can include polymers such as glycol, resin, dextrin, glue, polyethylene, ethylene, propylene, polyvinyl alcohol, or a combination thereof. In a particular instance, the bonding material may be a resin. Illustrative resins may include thermosets, thermoplastics, or a combination thereof. For example, resins can include phenolics, such as novolak and resole, epoxies, polyesters, such as unsaturated polyesters, cyanate esters, shellacs, polyurethanes, rubber, polyimides, bismaleimides, melamines, or a combination thereof.
Other embodiments may use a bonding material made of a composite material, including for example, a combination of organic and inorganic materials. For example, the bonding material can include a combination of a metal material combined with a polymer material (e.g., a resin).
In addition to the abrasive particles and bonding materials, the mixture may contain other materials, such as additives. It will be appreciated that additives may be included within the mixture to facilitate proper formation of the final abrasive body. Examples of such additives can include stabilizers, binders, surfactants, pore formers, and the like. The additives can also include lubricants, such as a graphite powder lubricant additive (50-150 mesh). In a particular aspect, such lubricant additives can be present in an amount less than or equal to 5.0 vol %.
Following formation of the mixture including abrasive particles and a binding material, the mixture can be formed into a preform, at step 104. For example,
After the preform has been placed in the mold, the process can continue, at step 108, by uniaxially hot pressing the preform within the mold (e.g., the loaded mold of
As described herein,
a and 2b depict an exemplary embodiment of a preform 200. As illustrated in
In another aspect, one or more of the preform surfaces 202, 204 may not be contoured, but may be flat and extend along and define a single plate. These surfaces 202, 204 may become contoured during the forming process and may remain contoured after the forming process.
As further illustrated in
In one embodiment, the preform 200 may be a green body. It will be appreciated that a green body can be an unfinished article, for example, an unsintered material. It will be further appreciated that a green body can be a body which is not fully densified, which may undergo further processing to affect grain growth and densification. The preform 200 may be formed by a variety of forming methods, including pressing, such as hot pressing or cold pressing, molding, casting, extruding, or a combination thereof. According to one particular process, the green body can be formed by cold pressing.
In particular instances, the forming process can include the formation of a green body that has a general shape which lacks at least one design feature of the finally-formed abrasive body formed through uniaxial hot pressing. Exemplary design features can include protrusions, recesses, patterned features, and the like.
The preform 200 can include a particular content of porosity within the green body, a particular content of abrasive particles within the green body, and a particular content of bonding material within the green body. Further, the content of porosity within the green body, the content of abrasive particles within the green body, and the content of bonding material within the green body can depend on a variety of factors. These factors can include, but are not limited to, the size of the preform 200, the percentage of compaction to be applied on the preform 200 during processing (i.e., the intended amount of volume shrinkage), the compactability of the bonding material within the green body, the compactability of the abrasive particles, and the compactability of any fillers or additives, etc.
Depending upon certain processing parameters, the properties of the preform 200 can change during the forming process. For example, the size of at least a portion of the pores can be reduced during the forming process. Moreover, at least a portion of the pores can be collapsed and eliminated during the forming process. As such, the porosity of the preform 200 can be reduced during the forming process, and the porosity of the abrasive tool formed from the preform can be less than the porosity of the preform 200 before the forming process. The concentration of abrasive particles can also change due to a change in the volume of the preform 200 during the forming process to form the abrasive tool. For example, as the volume of the preform 200 is reduced during formation, the concentration of abrasive particles can increase when expressed as a percentage of total volume. The forming process can be controlled to precise condition, such that the final content of the phases (e.g., bond material, abrasive particles, fillers, and even porosity) can be precisely controlled.
a depicts an exemplary embodiment of a mold 300 that is shaped to hold a single preform (e.g., the preform 200 of
In the embodiment illustrated in
As further illustrated, the mold 300 can include a rear portion 310. The rear portion can be configured to engage a portion of the preform 200 during pressing, and in particular, may engage the preform 200 along a portion of the rear surface 226 during pressing. According to one embodiment, the rear portion 310 of the mold 300 can include a recess 304. The recess 304 can be an opening extending into the volume of the rear portion 310. The recess 304 can be positioned adjacent to the opening 302 and be in fluid communication with the opening 302. The recess 304 may have a shape that corresponds to a design feature of the finally-formed abrasive body (e.g., a relief or a relief pattern). In one exemplary embodiment, the recess 304 can include a surface 314 defining a bottom surface of the recess 304 that is spaced apart from the front surface 312 of the rear portion 310. The surface 314 may have a particular contour, such as a smooth contour, or alternatively, a rough surface defined by patterned features or protrusions.
In particular instances, the recess 304 can extend along the full width of the rear portion 310 between side surfaces 333 and 334, such that the recess 304 intersects with the side surfaces 333 and 334. However, in other embodiments, the recess 304 may extend for a fraction of the full width of the rear portion 310.
According to one particular embodiment, the recess 304 can have a particular contour. For example, the contour of the recess 304 can be similar to the contour of the surfaces 318 or 319 of the mold 300. In particular, the recess 304 may have a curvilinear contour, defining a convex or concave arc.
b includes an illustration of an alternative embodiment. In particular,
Furthermore, the rear surface 226 of the preform 200 can be in direct contact with a surface 312 of the rear portion 310 of the mold 300. Notably, however, a portion of the rear surface 226 can be spaced apart from the rear portion 310 at the recess 304, wherein the recess 304 includes a surface 314 defining the bottom of the recess 304, and the surface 314 can be spaced apart from the rear surface 226 of the preform 200. The space between the surface 314 and the rear surface 226 may be filled with material of the preform 200 during the pressing process.
The mold pack 500 can include a second mold portion 520 including an upper portion 521 and a lower portion 522. The upper and lower portions 521 and 522 can have the features of mold portions described in the embodiments herein. In particular, the upper portion 521 can have a recess 523 formed in its front surface 525, wherein the recess 523 extends into the volume of the upper portion 521.
In particular, the mold pack 500 can utilize the first and second mold portions 510 and 520, which are oriented with respect to each other to facilitate processing of multiple preforms in a single pressing operation. Notably, during pressing, the first and second mold portions 510 and 520 can be uniaxially pressed and compressed uniformly at the same rate, such that the preforms 531 and 532 are processed simultaneously. In particular, the recesses 513 and 523 can be oriented with respect to the preforms 531 and 532 in the opposing mold portions 510 and 520 to facilitate suitable formation of features (e.g., reliefs) in the preforms 531 and 532 during pressing
While the exemplary mold pack 500 illustrated in
During a uniaxial pressing operation, a force (illustrated as “F” in
The forming process can include particular forming parameters. For example, the pressure applied may be dependent in part upon various factors, including but not limited to, particular components within the preform, content of phases within the preform, amount of shrinkage intended between the preform and the finally-formed bonded abrasive article, the temperature applied, the atmosphere, and the like.
According to one embodiment, a preform 602 that includes bonding material comprising metal can be uniaxially hot pressed at a pressure of at least about 4.9 MPa (710 psi). In other embodiments, the force applied during the uniaxial hot pressing operation can be a pressure on the preform 602 of at least about 9.8 Mpa (1421 psi), such as at least about 14.7 MPa (2132 psi), or even at least about 19.6 MPa (2842 psi). Still, according to one embodiment, the pressure may be not greater than about 44.1 MPa (6398 psi), such as not greater than about 39.2 MPa (5685 psi), not greater than about 34.3 MPa (4975 psi), or even not greater than about 29.4 MPa (4264 psi). It will be appreciated that the preform 602 that includes a binding material comprising metal may be uniaxially hot pressed at a pressure within a range including any of the minimum and maximum values noted above.
Uniaxial hot pressing may be conducted in a particular atmosphere. For example, in one process according to an embodiment, the preform 602 can be uniaxially hot pressed in an atmosphere comprising air. In another example, the preform 602 can be uniaxially hot pressed in an inert atmosphere. It will be appreciated that an “inert atmosphere” refers to an atmosphere that does not include gases that may react with the components of the preform 602 during pressing. In another example, the preform 602 can be uniaxially hot pressed in an oxidizing atmosphere. Alternatively, the preform 602 may be uniaxially hot pressed in a reducing atmosphere.
According to one embodiment, uniaxial hot pressing can include application of heat simultaneously with the application of a uniaxial force. The forming process can include particular forming temperature, which may be dependent in part upon various factors, including but not limited to, particular components within the preform, content of phases within the preform, amount of shrinkage intended between the preform and the finally-formed bonded abrasive article, the temperature applied, the atmosphere, and the like.
For example, for a preform 602 including a bonding material comprising metal, the uniaxial hot pressing can be conducted at a temperature of at least about 600° C. (1112° F.), such as at least about 650° C. (1202° F.), at least about 700° C. (1292° F.), or even at least about 750° C. (1382° F.). In a particular embodiment, the temperature may be not greater than about 1100° C. (2012° F.), such as not greater than about 1000° C. (1832° F.), not greater than about 900° C. (1652° F.), or even not greater than about 800° C. (1472° F.). It will be appreciated that uniaxially hot pressing may be conducted at a temperature within a range including any of the minimum and maximum temperatures noted above.
During the pressing operation, the preform 602 may be heated to a temperature such that the preform 602 is formed through a liquid phase sintering process. It will be appreciated that liquid phase sintering is a method of sintering, wherein at least a portion of one phase of the preform 602 (e.g., a portion of the bonding material) melts or becomes liquid. Notably, liquid phase sintering can also include the densification of the preform 602 into a finally-formed abrasive article. In one embodiment, liquid phase sintering can include changing at least a portion of the bonding material composition of the preform 602 into a liquid phase, wherein the liquid can change location within the mold 630 and facilitate changing the geometry of the preform 602 during the pressing operation. In particular instances, the combination of the composition of the preform 602 and the pressing operation can facilitate movement of the liquid phase through the preform 602 via capillary action to rearrange the unmelted particles into a more favorable packing arrangement.
Notably, during uniaxial hot pressing, a portion of the bonding material of the preform 602 may soften or melt, allowing a portion of the bonding material and abrasive particles to flow into one or more recesses of the mold 630, resulting in a substantial change in the geometry of the preform 602. The liquid phase of the bonding material may carry unmelted portions of the bonding material and unmelted abrasive grains into the recess. For example, the geometry of at least one surface of the preform 602 may be substantially altered during uniaxial hot pressing to include a relief projecting from a surface. According to a particular embodiment, at least a portion of the preform 602 can undergo liquid phase sintering and the liquid portion can flow into a recess (e.g., recess 304 of
In this manner, a net-shaped or near net-shaped abrasive body may be formed during the uniaxial hot pressing operation. It will be appreciated that a “net-shaped” abrasive body is one that has a geometry that is essentially the same as the intended shape provided by the mold 630 when the pressing operation is completed. A “net-shaped” abrasive body may not necessarily require further shape-altering processing. A “near net-shaped” abrasive body is one that has a geometry that is essentially the same as the intended shape provided by the mold 630 when the pressing operation is completed and may require final processing, albeit minimal final processing.
a includes an illustration of an abrasive article according to an embodiment. In particular, the abrasive article can include an abrasive body 900 defined by a top surface 902 and a bottom surface 904 opposite the top surface 902, which are separated by a length (L) of the abrasive body 900. In particular instances, the top surface 902 and the bottom surface 904 may have curved contours, and particularly, may define convex and concave surfaces, respectively. The abrasive body 900 can also include a side surface 927 extending at an angle to a front surface 925 and a rear surface 926, which may be a substantially orthogonal angle, and join the front surface 925 and the rear surface 926. The abrasive body 900 can also include a side surface 928, spaced apart from the side surface 927 by the width (W) of the body 900. The side surface 928 can extend at an angle to the front surface 925 and the rear surface 926, which may be a substantially orthogonal angle, and join the front surface 925 and the rear surface 926.
The abrasive body 900 can also be defined by a front surface 925 and a rear surface 926, separated from each other by a thickness (T). Notably, the abrasive body 900 can include a relief 990 in the form of a projection extending from the front surface 925. In particular instances, the relief 990 can be defined by a first surface 991 extending at an angle from the front surface 925 and a second surface 992 extending at an angle from the front surface 925 and spaced apart from the first surface 991 by a third surface 993. As illustrated, a first angle 995 can be defined between the first surface 991 and the third surface 993. The first angle 995 can be an acute angle, an obtuse angle, or a substantially orthogonal angle. According to the illustrated embodiment of
As also illustrated, a second angle 996 can be defined between the second surface 992 and the third surface 993. The second angle 996 can be an acute angle, an obtuse angle, or a substantially orthogonal angle. According to the illustrated embodiment of
As will be further appreciated, while the relief 990 is illustrated as having a particular cross-sectional polygonal shape, such that angles are defined between certain surfaces, other surfaces can be used to define other particular polygonal shapes. For example, the relief 900 can have a cross-sectional shape that is triangular, quadrilateral, pentagonal, hexagonal, or any other polygonal shape. Further, a quadrilateral relief can be a parallelogram, such as a rhombus, a rhomboid, a rectangle, or a square. Moreover, the quadrilateral relief can be a trapezoid, a trapezium, or an isosceles trapezoid. In another aspect, the relief 990 can be defined by one or more curvilinear surfaces, such that radiuses or rounded edges are utilized and the relief 990 can have a cross-sectional shape that is semicircular. Further, the relief can be formed into patterns that can include wording, letters, numbers, symbols, alphanumeric symbols, etc. In a particular aspect, the patterns formed by the relief can be used to identify the part in which the relief is formed.
According to an embodiment, the relief 990 can extend for at least a portion of the width (W) of the abrasive body 900 between the side surfaces 927 and 928. In another embodiment, the relief 990 can extend for a full dimension of the width (W) of the body 900, such that the relief 990 intersects the side surfaces 927 and 928. Furthermore, as illustrated, the relief 990 can be formed such that the surfaces 991, 992, and 993 have a curvature extending along the width (W) of the abrasive body 900. In particular, the surfaces 991, 992, and 993 defining the relief 990 can have a same curvature extending along the dimension of the width (W), and define a same arc as the curvatures of the top and bottom surfaces 902 and 904 of the abrasive body 900.
b includes a perspective view of the abrasive body 900. As illustrated, the abrasive body 900 can have an asymmetry in a plane 950 defined by the dimensions of the length (L) and the thickness (T) of the abrasive body 900. Notably, the relief 990 can extend at an angle from the front surface 925 and define an asymmetry to a plane that is parallel with an axis of pressing. In more detail,
In a one embodiment, the relief 990 may include a design on the surface of the abrasive body 900. For example, the relief 990 may include indicia, including for example, a logo, such as a company logo, a product logo, product number, or serial number. In particular instances, the relief 990 may be the indicia, including for example, a logo, such as a company logo, a product logo, product number, or serial number.
a, 10b, and 10c include illustrations of abrasive articles according to embodiments herein. In particular, the abrasive articles include abrasive bodies demonstrating alternative designs according to embodiments. For example,
As another example,
In a further example,
In a particular embodiment, prior to the forming process, the preform may include a particular content of porosity. For example, the preform can include at least about 20 vol % porosity, such as at least about 25 vol % porosity, at least about 30 vol % porosity, or even at least about 35 vol % porosity for the total volume of the preform. Still, the preform may include not greater than about 60 vol % porosity, such as not greater than about 55 vol % porosity, not greater than about 50 vol % porosity, or not greater than about 45 vol % porosity for the total volume of the preform. It will be appreciated that the preform may include a porosity content within a range including any of the minimum and maximum values provided above
According to another particular embodiment, upon completion of the forming process on the preform, the resulting abrasive body may include 0 vol % porosity. In another embodiment, the body may include a particular content of porosity. For example, the body may include at least about 1 vol % porosity, such as at least about 3 vol % porosity, at least about 5 vol % porosity, or even at least about 10 vol % porosity for the total volume of the body. Still, the body may include not greater than about 20 vol % porosity, such as not greater than about 15 vol % porosity for the total volume of the body. It will be appreciated that the body may include a porosity content within a range including any of the minimum and maximum values provided above.
According to another embodiment, upon completion of the forming process, the abrasive body may include a particular content of bonding material. For example, the body may include at least about 10 vol % bonding material for the total volume of the body. In certain other instances, the body can include at least about 15 vol % bonding material, at least about 20 vol % bonding material, or even at least about 25 vol % bonding material. Still, the body may include not greater than about 70 vol % bonding material, such as not greater than about 65 vol % bonding material for the total volume of the body. It will be appreciated that the body may include an amount of bonding material within a range including any of the minimum and maximum values provided above.
In a particular embodiment, for uniaxial hot pressing along a length, L, of a preform, the length, L, is selected by considering, for example, the compactability of the mixture that comprises the preform and the expected life of the compaction tools used to form the preform. The final length of the preform should be selected such that wear on the compaction tools due to the abrasive particles in the preform mixture is limited while providing sufficient compaction so the preform is sufficiently strong enough to be handled readily without breaking when placed in a mold. For a bonding material comprising 30-100 wt % bronze and 40-60 wt % iron and a final abrasive content of 2-12.5 vol % (as measured in the final abrasive body), the compaction pressure can be within a range that is between and includes about 68.9 Mpa (10.0 ksi) to about 441.3 MPa (64.0 ksi), the hot pressing temperature can be within and include a range of about 600° C. (1112° F.) to about 1100° C. (2012° F.), and the hot pressing pressure can be within and include a range of about 4.9 MPa (710 psi) to about 44.1 MPa (6398 psi).
In one instance, an abrasive body includes a preform mixture that includes:
The preform mixture is compacted at a compaction pressure of about 372 MPa (54 ksi) to form a preform that includes a length that is about 1.8 times greater than the final abrasive body. The preform is hot pressed at a temperature of about 900° C. (1652° F.) and a pressure of about 19.6 MPa (2842 psi) to form the abrasive body.
The embodiments herein represent a departure from the state-of-the-art. Traditionally, bonded abrasive articles are formed through processes such as cold pressing or hot pressing. In such processes, forces are applied evenly across the surface of the preform to form the finally-formed abrasive body. Moreover, with respect to uniaxial pressing operations, such a process is reserved in the industry for those materials having uniform compositions. Materials having heterogeneous compositions are regarded as having differential compaction dynamics that can result in density gradients within the finally-formed body and thus a poorly formed and unfit article. However, the present embodiments are directed to uniaxial hot pressing of heterogeneous bodies including abrasive particles and bonding material to form bonded abrasive articles. The embodiments herein utilize a combination of features, which include, but are not limited to, compositions of the preform, shape of the preform, composition and shape of the molds, processing parameters including pressure, temperature, and atmosphere, liquid phase sintering, and changes in geometry between the preform and finally-formed abrasive article, which facilitate the forming process and attributes of the finally-formed bonded abrasive bodies.
In the foregoing, reference to specific embodiments and the connections of certain components is illustrative. It will be appreciated that reference to components as being coupled or connected is intended to disclose either direct connection between said components or indirect connection through one or more intervening components as will be appreciated to carry out the methods as discussed herein. As such, 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 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. 61/540,972 entitled “Bonded Abrasives Formed by Uniaxial Hot Pressing,” by Marc Linh Hoang filed Sep. 29, 2011, which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61540972 | Sep 2011 | US |
