Patent Application
20140069727
The use of constructions comprising ultra-hard and metallic components that are joined together is well known in the art. An example of such may be found in the form of cutting elements comprising an ultra-hard component that is joined to a metallic component. In such cutting element embodiment, the wear or cutting portion is formed from the ultra-hard component and the metallic portion of the cutting element is attached to the wear and/or cutting device. In such known constructions, the ultra-hard component may be formed from a polycrystalline material such as polycrystalline diamond (PCD), polycrystalline cubic boron nitride (PcBN), or the like, that has a degree of wear and/or abrasion resistance that is greater than that of the metallic component.
In particular examples, the ultra-hard component may be PCD that has been treated so that it is substantially free of a catalyst material, e.g., a Group VIII metal from the Periodic table, that was used to form/sinter the same at high-pressure/high-temperature conditions, and that comprises bonded-together diamond crystals. PCD that has been rendered substantially free of the catalyst material is referred to as thermally stable polycrystalline diamond (TSP), as removal of the catalyst material has been found to improve the thermal stability of the resulting diamond body by eliminating unwanted degradation and thermal expansion mismatches that with increasing temperature may adversely impact the effective service life of the diamond body.
While TSP provides desired improvements in thermal stability, a problem known to exist with TSP is that its lack of catalyst material within the body operates to preclude subsequent attachment of the TSP body to a metallic substrate by solvent catalyst infiltration. Further, such TSP bodies have a coefficient of thermal expansion that is sufficiently different from that of conventional substrate materials (such as cermets like WC—Co and the like) that are typically infiltrated or otherwise attached to a PCD body. Attaching such substrates to the TSP body is highly desired to provide a TSP compact that may be readily adapted for use in many desirable applications. However, the difference in thermal expansion between the TSP body and the substrate, and the poor wettability of the TSP body due to the substantial absence of the catalyst material, makes it very difficult to bond the TSP body to conventionally used substrates. Thus, some TSP bodies are attached or mounted directly to the desired end-use device without the presence of an adjoining substrate.
It is known that TSP bodies may be attached to a desired metallic substrate through the use of active braze materials, which are known to have relatively low melting temperature and low yield strengths. Combining the known limitations of active braze materials with the inherently poor wettability of the TSP body, the braze joint attachment that is formed between the TSP body and the substrate is one that is not as strong as the attachment bond formed between conventional PCD and a metallic substrate by infiltration. The resulting construction is one having a diminished service life due to the low yield strength of the braze material, which leads to delamination between the TSP body and the substrate during service.
Ultra-hard construction disclosed herein comprise a diamond-bonded body comprising a matrix phase of bonded-together diamond grains and a plurality of interstitial regions interposed between the bonded-together diamond grains. The interstitial regions are substantially free of a catalyst material used to sinter the diamond-bonded body at high-pressure/high-temperature conditions. A metal material is disposed on a substrate interface surface of the diamond body. In an example embodiment, the metal material has a carbide constituent. In an example embodiment, the metal material has a layer thickness in the range of from about 0.1 to 10 microns. The construction further includes a substrate connected with the diamond-bonded body. The substrate may comprise a carbide constituent. The substrate is attached to the diamond-bonded body through a braze joint interposed between the metal material and the substrate. The braze joint is formed from a non-active braze material that reacts with the substrate and metal material. In an example embodiment, the braze joint is formed at the melting temperature of the non-active braze material in the absence of high-pressure conditions. The diamond-bonded body of such ultra-hard constructions is made at high-pressure/high-temperature conditions. A substrate interface surface of the so-formed body is treated to include the metal material layer thereon. A metallic substrate is attached to the diamond-bonded body by the braze joint comprising the non-active braze material at approximately the melting temperature of the braze material in the absence of high-pressure conditions. If desired, a carburizing treatment can be performed prior attaching the substrate. This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
Embodiments of ultra-hard constructions are described with reference to the following figures:
Ultra-hard and metallic constructions as disclosed herein comprise a thermally stable polycrystalline diamond (TSP) bonded body that is substantially free of a catalyst material initially used to sinter the body, and that is specially engineered to accommodate attachment with a substrate or end-use device by a braze joint in a manner that provides an enhanced degree of attachment strength therewith when compared to conventional TSP constructions.
As used herein, the term “ultra-hard” is understood to refer to those materials known in the art to have a grain hardness of about 4,000 HV or greater. Such ultra-hard materials may include those capable of demonstrating physical stability at temperatures above about 750° C., and for certain applications above about 1,000° C., that are formed from consolidated materials. Such ultra-hard materials may include but are not limited to diamond, cubic boron nitride (cBN), diamond-like carbon, boron suboxide, aluminum manganese boride, and other materials in the boron-nitrogen-carbon phase diagram which have shown hardness values similar to cBN and other ceramic materials.
Polycrystalline diamond (PCD) is a useful material for forming the ultra-hard component once it has been treated to remove a catalyst material, such as the Group VIII materials noted above, used to initially sinter or form the same at high-pressure/high-temperature (HPHT) conditions. As used herein, the term “catalyst material” refers to the material that was initially used to facilitate diamond-to-diamond bonding or sintering at the initial HPHT process conditions used to form the PCD.
TSP has a material microstructure characterized by a polycrystalline matrix phase comprising bonded-together diamond grains or crystals, and a plurality of voids or empty pores that exist within interstitial regions within the matrix disposed between the bonded-together diamond grains. The TSP material is initially formed by bonding together adjacent diamond grains or crystals at HPHT process conditions. The bonding together of the diamond grains at HPHT conditions is facilitated by the use of an appropriate catalyst material, such as a metal solvent catalyst selected from Group VIII of the Periodic table, thereby forming conventional PCD comprising the catalyst material disposed within the plurality of voids or pores.
Diamond grains useful for forming the TSP component or body may include natural and/or synthetic diamond powders having an average diameter grain size in the range of from submicrometer in size to 100 micrometers, and in the range of from about 1 to 80 micrometers. The diamond powder may contain grains having a mono or multi-modal size distribution. In an example embodiment, the diamond powder has an average particle grain size of approximately 20 micrometers. In the event that diamond powders are used having differently sized grains, the diamond grains are mixed together by conventional process, such as by ball or attritor milling for as much time as necessary to ensure good uniform distribution.
The diamond grain powder is cleaned, to enhance the sinterability of the powder by treatment at high temperature, in a vacuum or reducing atmosphere. The diamond powder mixture is loaded into a desired container for placement within a suitable HPHT consolidation and sintering device.
The diamond powder may be combined with a desired catalyst material, e.g., a solvent metal catalyst, in the form of a powder to facilitate diamond bonding during the HPHT process and/or the catalyst material may be provided by infiltration from a substrate positioned adjacent the diamond powder and that includes the catalyst material. Suitable substrates useful as a source for infiltrating the catalyst material may include those used to form conventional PCD materials, and may be provided in powder, green state, and/or already sintered form. A feature of such substrate is that it includes a metal solvent catalyst that is capable of melting and infiltrating into the adjacent volume of diamond powder to facilitate bonding the diamond grains together during the HPHT process. In an example embodiment, the catalyst material is cobalt (Co), and a substrate useful for providing the same is a Co containing cermet material, such as WC—Co.
The diamond powder mixture may be provided in the form of a green-state part or mixture comprising diamond powder that is combined with a binding agent to provide a conformable material product, e.g., in the form of diamond tape or other formable/conformable diamond mixture product to facilitate the manufacturing process. In the event that the diamond powder is provided in the form of such a green-state part, it is desirable that a preheating step take place before HPHT consolidation and sintering to drive off the binder material. In an example embodiment, the PCD material resulting from the above-described HPHT process may have diamond volume content in the range of from about 85 to 95 percent.
The diamond powder mixture or green-state part is loaded into a desired container for placement within a suitable HPHT consolidation and sintering device. The HPHT device is activated to subject the container to a desired HPHT condition to effect consolidation and sintering of the diamond powder. In an example embodiment, the device is controlled so that the container is subjected to a HPHT process having a pressure of 5,000 MPa or greater, and a temperature of from about 1,350° C. to 1,500° C. for a predetermined period of time. At this pressure and temperature, the catalyst material melts and infiltrates into the diamond powder mixture, thereby sintering the diamond grains to form PCD. After the HPHT process is completed, the container is removed from the HPHT device, and the so-formed PCD material is removed from the container.
In the event that a substrate is used during the HPHT process, e.g., as a source of the catalyst material, the substrate is removed prior to treating the PCD material to remove the catalyst material therefrom to form TSP. The substrate may be removed during or after the treatment to form TSP. In an embodiment, any substrate is removed prior to treatment to expedite the process of removing the catalyst material from the PCD body.
The term, “removed,” as used with reference to the catalyst material after the treatment process for forming TSP, is understood to mean that a substantial portion of the catalyst material no longer resides within the remaining diamond bonded body. However, it is to be understood that some small amount of catalyst material may still remain in the resulting diamond bonded body, e.g., within the interstitial regions and/or adhered to the surface of the diamond crystals. Additionally, the term, “substantially free,” as used herein to refer to the catalyst material in the diamond bonded body after the treatment process, is understood to mean that there may still be some small/trace amount of catalyst material remaining within the TSP material as noted above. Rather than removing the catalyst material from the PCD, the PCD may be rendered TSP by treating the catalyst material used to form the PCD in such a manner so as to render the catalyst material nonreactive or noncatalytic at construction operating temperatures.
In an example embodiment, the PCD body is treated to render the entire body substantially free of the catalyst material. This may be done, by subjecting the PCD body to chemical treatment such as by acid leaching or aqua regia bath, electrochemical treatment such as by electrolytic process, by liquid metal solubility, or by liquid metal infiltration that sweeps the existing catalyst material away and replaces it with another noncatalyst material during a liquid phase sintering process, or by combinations thereof. This process may be conducted under conditions of elevated temperature, elevated pressure, high-frequency vibration and combinations thereof. In an example embodiment, the catalyst material is removed from the PCD body by an acid leaching technique, such as that disclosed for example in U.S. Pat. No. 4,224,380.
The TSP may be formed using thermally stable catalyst systems such as carbonates, sulfites or pyrites. In such cases temperatures above 2000° C. and pressures over 7.0 GPa may be required to form the TSP body. In an additional embodiment, the TSP may be formed from graphitic or non-diamond carbon sources which will require temperatures greater than 2000° C. pressures above 10.0 GPa.
The so-formed TSP body is treated prior to being attached to a substrate by use of a braze joint, which substrate may be provided in the form of part that is separate from the end-use device, such as a substrate that is conventionally used for making PCD compacts, or may be in the form of the end-use device itself. The treatment comprises applying a layer of metal material to a surface of the TSP body positioned to interface with the substrate, i.e., a substrate interface surface. The metal material is provided for the purpose of enhancing the strength of the attachment that is formed with the substrate through the braze joint, to thereby provide an improved service life by avoiding substrate delamination.
In an example embodiment, the TSP body is treated by depositing the metal material thereon by any suitable deposition process, e.g., by dipping, by spray, CVD process, sputtering process, or the like. In an example embodiment, it is desired that a metal material be one that includes carbide and/or that is a carbide former, e.g., that forms carbide upon subsequent treatment. It is desired that the metal material be applied in sufficient amount and/or thickness to provide a desired amount of carbide at the substrate interface for the purpose of permitting the use of a non-active braze to join the substrate and TSP body together. In some instances, more than one layer of the metal material may be applied to achieve the desired amount or content of carbide on the TSP body surface.
In an example embodiment, the thickness of the metal layer may be in the range of from about 0.1 to 10 microns, in the range of from about 0.5 to 5 microns, and in the range of from about 1 to 3 microns. It is understood that the exact thickness of the metal layer that is used will depend on the type of metal material being applied as well as the type of braze material being used. The treatment may be one that provides a surface coating of the metal material onto the substrate interface surface and/or that introduces the metal material into a region of the TSP body that extends a partial depth from the substrate interface surface.
Metal materials useful for this treatment may include metallic materials, metals, metal alloys, and the like that either include carbide or that are produce carbide, e.g., are carbide formers, upon further treatment. As noted above, the metal material is used to provide a desired amount of carbide on the TSP body to permit the use of non-active braze materials in joining the TSP body to the substrate. The use of such non-active braze materials is desired because they provide a strong attachment bond with the metallic substrate and have a relatively higher yield strength and melting temperature than active braze materials conventionally used in the process of joining diamond-bonded bodies (PCD and TSP) to a cermet substrate. As used herein, the term “active braze” means a braze material that reacts the polycrystalline ultra-hard material (untreated). The term “non-active braze” means a braze material that does not react with the polycrystalline ultra-hard material (untreated).
Suitable carbide containing metal materials useful for this treatment include B, Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, and combinations and alloys thereof. Example carbide-containing metal materials include and are not limited to B4C, SiC, TiC, ZrC, HfC, VC, NbC, TaC, Cr2C3, CrC2, Mo2C, MoC, W2C and WC.
Suitable carbide-forming metal materials useful for this treatment include those that are capable of forming a carbide when subjected to a carburizing process, which carburizing process may be conducted as a step separate from brazing or during the brazing process. Suitable carbide-forming materials include refractory metals such as those selected from Groups IV through VII of the Periodic table. In an example embodiment, the metal material is tungsten (W), and the layer of tungsten is carburized such that the primary constituent on the substrate interface surface is tungsten carbide (WC). The metal material is titanium and the carbide is titanium carbide (TiC).
It is desired that the metal material used for this treatment be one that produces a desired level or content of carbide on the substrate interface surface to facilitate use of a non-active braze material to join the substrate and TSP body together. Non-active braze materials are ones uniquely suited to form a strong bond with a carbide containing surface. Thus, treating the TSP body substrate interface surface in this matter provides such a carbide surface on the TSP body to match the carbide already present on the surface of the substrate, thereby ensuring that a strong brazed attachment is formed therebetween. Additionally, because non-active braze materials have a relatively higher yield strength and melting temperature than active braze materials (that are conventionally used to join polycrystalline bodies to metallic substrate), the braze joint formed by the non-active braze material is less apt to delaminate and fail during service, thereby enhancing the service life of ultra-hard constructions that are formed therefrom.
The metal material used to facilitate brazed attachment between the TSP body and substrate may also serve as a barrier to prevent any unwanted migration or infiltration of material into the TSP body during the braze operation. Additionally, the metal material may help to accommodate any mismatch in mechanical properties that exist between the TSP body, the braze material, and the substrate, e.g., differences in thermal expansion characteristics, that may create high residual stresses in the construction during the attachment process. The residual stress mismatch may be helped by having a tungsten or titanium layer that contains a gradient composition with respect to carbide content, for example containing approximately 90% or higher carbide near the ultra-hard material interface, and 50% or lower carbide content at the interface to be joined with a non-active braze.
A treatment providing a coated surface may be desired in instances where maximum thermal protection of the TSP cutting edge or working surface is required. An additional barrier layer coating may optimize the thermal gradient into the TSP body and thereby prolong cutting life. In an example embodiment where a coated surface is provided, the coating may extend a thickness measured from the substrate interface surface of the TSP body of from about 1 to 5 microns, from about 5 to 20 microns, and more than about 20 microns.
A treatment providing an infiltrated region within the TSP body may be desired in instances where an enhanced attachment strength between the substrate and TSP body is desired and provided by the bonding of the braze material, in addition to the surface of the TSP body, to the region within the TSP body comprising the metal material. In an example embodiment, where infiltration of the metal material is desired, the infiltration depth may be in the range of from about 1 to 20 microns.
In an embodiment where the metal material is additionally selected to act as a barrier material, its presence operates to prevent unwanted migration of constituents from the braze joint and/or substrate into the TSP body. Additionally, the presence of such a barrier metal material may operate to block unwanted infiltration of the any materials from the from the TSP body into the adjacent braze joint or substrate.
Once the TSP body has been treated to include the metal material, it may be subjected to further treatment prior to being braze attached to the substrate. In the event that the metal material applied to the TSP body already contains carbide, then the TSP body may be brazed without further treatment. In the event that the metal material applied to the TSP body was a carbide former and does not already contain carbide, then further treatment will take place to form the desired carbide constituent. In an example embodiment, such further treatment may comprise carburizing the metal material at an elevated temperature in the range of from about 700 to 1,500° C. In an example embodiment, the carburizing process takes place at a temperature of about 900° C. for an amount of time sufficient to create the desired carbide. Temperatures and times may also be manipulated to create a desired gradient condition in the metallic layer.
The step of forming the carbide constituent in the metal material, e.g., by carburizing, may take place separately and independent from the step of brazing the TSP body to the substrate. The step of forming the carbide constituent may take place during the step of brazing, e.g., immediately before joining together the TSP body and the braze material.
Suitable non-active braze materials useful in forming ultra-hard constructions as disclosed herein include those selected from the group including Cu, Ni, Mn, Au, Pd and combinations and alloys thereof. Example alloys include those having the following composition and liquid temperature (LT) and solid temperature (ST), where the composition amounts are provided in the form of weight percentages: 40 Ni, 60 Pd, LT=ST=1,238° C.; 70 Au, 22 Ni, 8 Pd, LT=1,037° C., ST=1,005° C.; 35 Au, 31.5 Cu, 14 Ni, 10 Pd, 9.5 Mn, LT=1,004° C., ST=971° C.; 52.5 Cu, 9.5 Ni, 38 Mn, LT=925° C., ST=880° C.; 31 Au, 43.5 Cu, 9.75 Ni, 9.75 Pd, 16 Mn, LT=949° C., ST=927° C.; 54 Ag, 21 Cu, 25 Pd, LT=950° C., ST=900° C.; 67.5 Cu, 9 Ni, 23.5 Mn, LT=955° C., ST=925° C.; 58.5 Cu, 10 Co, 31.5 Mn, LT=999° C., ST=896° C.; 35 Au, 31.5 Cu, 14 Ni, 10 Pd, 9.5 Mn, LT=1,004° C., ST=971° C.; 25 Su, 37 Cu, 10 Ni, 15 Pd, 13 Mn, LT=1,013° C., ST=970° C.; and 35 Au, 62 Cu, 3 Ni, LT=1,030° C., ST=1,000° C.
The TSP body (comprising the carbide-containing substrate interface surface) is joined to the substrate through the braze material under elevated temperature conditions sufficient to melt the braze material. The braze joint may be formed by using conventional braze techniques such as by vacuum brazing, induction brazing, and the like. Thus, a further feature of ultra-hard constructions disclosed herein is that the TSP body is attached to the substrate by brazing at elevated temperature without elevated pressure, i.e., without having to subject the TSP body to a second HPHT process. Avoiding the need to rely on an HPHT process for attaching the TSP body to the substrate is highly desired as it improves manufacturing efficiency and reduces related manufacturing costs, and avoids unwanted infiltration issues.
Example braze materials useful for forming the braze joint include materials that are capable of forming a strong chemical bond between the TSP body and a desired substrate. It is desired that the braze material includes one or more elements that are capable of reacting with one or more elements in the TSP body to form such strong chemical bond. For this reason, materials useful for forming the braze material may be referred to as being “active” braze materials or alloys.
As noted above, the substrate useful in forming ultra-hard constructions as disclosed herein may be provided in the form of a part that is separate from the end-use device, such as a cermet or carbide part, or may be provided in the form a portion of the end-use device itself. Accordingly, it is to be understood that TSP bodies that have been treated in the manner described above may be attached directly or indirectly to the end-use device by the above-described braze joint.
Suitable substrates that are provided separate from the end-use device may be selected from those materials conventionally used as substrates for forming PCD compacts, and may include metallic materials, ceramic material, cermet materials, and combinations thereof. An example substrate is one that is a carbide, such as one formed from WC—Co. The size and configuration of the substrate may and will vary depending on the size and configuration of the TSP body and the end-use application. Various types of steels may be employed as substrates and may include or be later machined to contain features such as threads or other fastener devices to facilitate convenient mechanical attachment to a drill bit. Wherein the types of steels useful as a substrate include those having a Rockwell C hardness of 50 or more.
While particular example embodiment ultra-hard constructions have been disclosed above and illustrated, it is understood that variations of these example embodiment are understood to be within the scope of what is being disclosed herein.
A feature of ultra-hard constructions as disclosed herein is that the TSP body included therein has been treated to include a metal material prior to brazed attachment with a substrate, wherein such metal material either includes or is treated to include a carbide constituent. A further feature of such ultra-hard constructions as disclosed herein is that the braze material used to form the braze joint is a non-active braze material that is well suited to form an improved degree of bond strength between carbide containing surfaces, as they currently exist on both the TSP body and the substrate. A further feature of such ultra-hard constructions is that the non-active braze material has a relatively higher yield stress and melting temperature as compared to active braze materials conventionally used to form the braze joint between the TSP body and the substrate, thereby improving service life by minimizing unwanted delamination while in service. A still further feature of such ultra-hard constructions is the avoidance of having to undergo HPHT processing to attach the TSP body to the substrate, wherein the braze joint is formed at the braze material melting temperature without the need for elevated pressure, thereby improving manufacturing efficiency and reducing related manufacturing costs.
Ultra-hard constructions as disclosed herein may be used in a number of different applications, such as tools for mining, cutting, machining, milling and construction applications, wherein properties of shear strength, thermal stability, wear and abrasion resistance, mechanical strength, and/or reduced thermal residual stress are highly desired. Ultra-hard constructions as disclosed herein are particularly well suited for forming working, wear and/or cutting elements in machine tools and drill and mining bits such as roller cone rock bits, percussion or hammer bits, diamond bits, and shear cutters used in subterranean drilling applications.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.
This application claims the benefit of co-pending U.S. Provisional Patent Application Ser. No. 61/698,408 filed on Sep. 7, 2012, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61698408 | Sep 2012 | US |
