The present invention relates to a method of making a dense, highly impact resistive and/or thermally conductive diamond body.
The prior art include U.S. Pat. No. 5,266,236, which discloses a method of making a thermally stable, dense and electrically conductive diamond compacts. The method comprises infiltrating a mass of diamond crystals with a silicon infiltrant in the presence of boron under conditions comprising a temperature of not substantially above 1200 degree C. and a pressure of not substantially above 45 Kbar. The resulting compact contains diamond-to-diamond bonding. The boron can be provided in the form of boron doped diamond. Alternatively, a boron-silicon alloy can be used for infiltrating boron doped or undoped diamond. Further, boron can be added as elemental boron or B.sub.4 C with silicon for infiltration. Alternatively, boron metal catalyst plus silicon infiltration can be used for boron-doped or undoped diamond. Combinations of these techniques also can be used. In the HP/HT process, the silicon infiltrates the diamond powder mass forming a network composed of silicon carbide by reaction of the silicon with diamond-carbon. The reaction leaves a sintered body composed of boron-doped diamond or boron compounds with diamond or a network of silicon carbide and silicon.
U.S. Pat. No. 5,127,923 discloses that an abrasive compact with a substantially solid body is provided from a mass of abrasive particles which are bonded together on a particle-to-particle basis. A network of interstices is formed within the body by removing the metallic second phase by-product of a solvent catalyst sintering aid. The network of interstices is filled with the carbide by product of a non-catalyst sintering aid forming a solid body. A substrate is bonded to some of the particles and to some of the carbide filling the network of interstices.
Other references from the prior art include U.S. Pat. No. 4,231,762 to Hara et al., U.S. patent application Ser. No. 12/366,706 to Hall, U.S. Pat. No. 4,931,068 to Dismukes et al., U.S. Pat. No. 5,151,107 to Cho et al., U.S. Pat. No. 4,948,388 to Ringwood, which are all herein incorporated by reference for all they contain.
In one aspect of the invention, a method of making a dense diamond body comprises the steps of: forming a sintered polycrystalline diamond body with the use of a catalyst; forming voids in the body by removing at least some of the catalyst; and reducing the overall volume of the voids by applying pressure and temperature to the body in a vessel substantially free of additional catalysts.
The step of forming the sintered polycrystalline diamond may include sintering multiple diamond bodies in a single can at the same time. The temperature for removing the voids may be at least 1000 degree Celsius. The pressure may be at least 3 GPa. The steps of forming voids may include leaching of catalyst material. The method may include an additional step of bonding the diamond body to a cemented metal carbide substrate after the step of reducing the overall volume of the body's voids. An infiltrant barrier may be placed intermediate the substrate and the diamond body. The step of bonding the diamond body to a substrate may be done in a press at a temperature lower than 1600 degree Celsius. The step of bonding the diamond body to a substrate may be done in a press at a pressure lower than 7 GPa.
The diamond bodies may be separated by a metal layer that has a melting temperature above the temperature applied in the step to reduce the overall volume. The vessel may be surrounded by a pressure transferring medium that is pre-compacted at a temperature less than 500 degree Celsius and a pressure of less than 1 GPa.
The diamond body may comprise portions with different geometries including: a substantially conical shaped geometry, a substantially cylindrical shape, a substantially chisel-shaped geometry, and/or a substantially dome-shaped geometry.
In some embodiment, at least 25 percent of the catalyst may be removed. In other embodiments, at least 90 percent of the catalyst may be removed. In yet other embodiments, at least 99 percent of the catalyst may be removed. The method may include an additional step of attaching the diamond to an electric component or to a driving mechanism.
a is a schematic diagram of an embodiment of a polycrystalline diamond segment.
b is a schematic diagram of another embodiment of a polycrystalline diamond segment.
c is a schematic diagram of another embodiment of a polycrystalline diamond segment.
The diamond enhanced shear cutters 105 reduce wear on the bit face 102 and blades 170 as the bit 100 advances further into subterranean formations. The shear cutters 105 have a diamond body 180 bonded to a substrate, preferably made of cemented metal carbide. The shear cutters 105 are attached to the blade 170, usually by brazing, although in alternative embodiments welding or press fitting may be used.
In some embodiments, only a single layer of diamond is contained in the can 200. Regardless of the number of the layers in the can, the diamond mixes 250 should be thoroughly cleaned before sealing the can's lid 240 in place. The cleansing process may include heating the can 200 in a substantially inert atmosphere or a vacuum to vent the impurities out of the can 200. When the mixes 250 are believed to be cleansed, the temperature may be increased for a short duration to melt a sealant material between the can 200 and the lid 240, thereby sealing them together. A compatible sealing method that may be compatible with the present invention is described in U.S. patent application Ser. No. 11/469,229, which is herein incorporated by reference for all that it discloses.
In embodiments where a plurality of diamond mixes 250 is divided into layers, niobium disks 230 may be used as separators. Niobium is a preferred metal because of its high melting temperature, relatively low cost, and chemical activity toward volatile impurities that may remain in the diamond mixes 250.
Preferably, the can 200 described above is placed in this chamber 300 after the cleaning process is complete. Typically, the can 300 will be first packed into the cavity of a deformable cube 355 together with a pressure transferring medium such as a salt, usually sodium chloride. As the anvils 370 advance together, the deformable material extrudes into the gaps between the anvil edges and forms a gasket. A reaction cell within cube 355 is heated to high temperature by conducting electricity between two opposing anvils 370 with a resistive heater inside the cube 355, completing the electrical circuit. The pressure transferring medium within the cube 355 acts to uniformly distribute the pressure from the advanced anvils 370 to the diamond mixes 250. Under such high pressure and temperature, the catalysts in the diamond mixes 250 promote diamond to diamond bonding resulting in a sintered polycrystalline diamond body with a metal catalyst dispersed through interstices of the bonded diamond grains.
a discloses a cross-sectional view of a diamond body 420 after sintering in the internal chamber 300. The diamond body 420 comprises polycrystalline diamond grains 400 bonded together with interstitial regions filled with catalyst 410. During sintering, external pressure pushed the diamond grains 400 close together until the diamond/metal composite was as dense as possible. Under such pressure, it is believed that the metal catalyst actually resisted attainment of a denser diamond product by reactively pushing back on the diamond grains 400.
b discloses a sintered diamond body 420 with the catalyst removed, thereby creating voids 430 that were previously occupied with catalyst. In the preferred embodiment, all of the catalyst is removed; however, in some alternative embodiments, only a portion of the catalyst is removed. For illustrative example, in some embodiments, only 25, 90, or 99 percent of the catalyst is removed. The amount of catalyst removed may range from 1 to 100 percent. The catalyst may be removed through a chemical leaching process or by other removal mechanisms known in the art. Leaching agents that may be compatible with the present invention may include acids, particularly a mixture of hydrofluoric acid and nitric acid or alkali aqueous solutions. Other catalyst removal mechanisms may include electrolytic leaching or sputtering.
c discloses recompacting the sintered diamond body 420 after the catalyst is removed. It is believed that without resistance from the catalyst to the external pressure applied to the diamond bodies, that the bodies may become denser and result in a fully dense polycrystalline diamond body. In embodiments where only a portion of the catalyst is removed, it is believed that the diamond body will still achieve higher overall density than was previously possible.
The recompacting may be done in the internal chamber 300 at high temperatures and pressures. The diamond bodies are preferably disposed within a vessel substantially free of any metal catalyst. A vessel made of niobium may be preferable because of niobium's high melting temperature. In some embodiments, a small amount of catalyst, substantially smaller in volume than the total volume occupied by the voids after catalysts removal, may also be placed in the vessel to promote new diamond to diamond bonding during recompaction. In embodiments, where only a portion of the catalyst was removed, the remaining catalyst may be sufficient to promote the new bonds.
Before recompacting the diamond bodies, they may be pre-compacted in the internal chamber 300 by the advancement of the anvils 370. Preferably, no temperature is applied in this step. The pre-compacting is believed to further help condense the diamond body 420.
Referring to
Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.
This application is a continuation in-part of U.S. patent application Ser. No. 11/691,978, which is a continuation-in-part of U.S. patent application Ser. No. 11/673,634, which is a continuation-in-part of U.S. patent application Ser. No. 11/668,254, which is a continuation-in-part of U.S. patent application Ser. No. 11/553,338. All of these applications are herein incorporated by reference for all that they contain.
Number | Date | Country | |
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Parent | 11691978 | Mar 2007 | US |
Child | 12493013 | US | |
Parent | 11673634 | Feb 2007 | US |
Child | 11691978 | US | |
Parent | 11668254 | Jan 2007 | US |
Child | 11673634 | US | |
Parent | 11553338 | Oct 2006 | US |
Child | 11668254 | US |