Specialized metallurgical processes – compositions for use therei – Compositions – Consolidated metal powder compositions
Patent
1994-07-26
1995-12-19
Mai, Ngoclan
Specialized metallurgical processes, compositions for use therei
Compositions
Consolidated metal powder compositions
C22C 2908, C22C 2910
Patent
active
054765315
DESCRIPTION:
BRIEF SUMMARY
This invention generally concerns cemented refractory metal matrix composites. This invention particularly concerns rhenium-bound tungsten carbide, rhenium-bound hafnium carbide and rhenium-bound titanium carbide metal matrix composites. This invention more particularly concerns the use of substantially pure rhenium metal as a binder for tungsten carbide, hafnium carbide or titanium carbide.
Cemented carbides, also known as "hard metals", conventionally include a basic carbide, such as tungsten carbide, and an iron group metal, such as cobalt, as a binder. U.S. Pat. No. 4,432,794 discloses binder metal alloys that comprise a solid alloy of a transition metal of Group IVb, Vb or VIb with Re, Ru, Rh, Pd, Os, Ir or Pt. Lisovsky et al., in "Structure of a Binding Phase in Re-Alloyed WC-Co Cemented Carbides", Refractory Metals & Hard Materials, Volume 10 (1991), pages 33-36, discuss the effects of alloying WC-Co cemented carbides with rhenium.
Tools made of cemented carbide, including WC-Co (tungsten carbide-cobalt) as a typical composition, are widely used in the machining field. The alloy compositions, characteristics, uses and applications of such cemented carbide materials are summarized in Cemented Carbides for Engineers and Tool Users, International Carbide Data (1983 ).
SUMMARY OF THE INVENTION
The present invention is a dense refractory composition-consisting essentially of rhenium in an amount within a range of from 1 to 25 percent by weight of composition and a refractory metal carbide selected from tungsten carbide, hafnium carbide and titanium carbide in an amount within a range of from 75 to 99 percent by weight of composition.
The dense refractory compositions can be used in any one of a number of conventional applications for hard metals. One such application is as a cutting tool used in machining or cutting a variety of materials such as metals, plastics and wood products. Cutting tools include indexable inserts, end mills, router bits, reamers, drills, saw blades and knives.
DESCRIPTION OF PREFERRED EMBODIMENTS
The refractory metal carbide is suitably tungsten carbide, hafnium carbide or titanium carbide. Tungsten carbide yields particularly desirable results. The tungsten carbide has an average grain size that is suitably about ten micrometers or less, beneficially about five micrometers or less, desirably about one micrometer or less, and preferably from 0.4 to 0.8 micrometer. Acceptable grain sizes for other carbides approximate those for tungsten carbide and can be readily determined without undue experimentation. The refractory metal is preferably in powder or particulate form.
Rhenium metal powder suitable for purposes of the present invention has a particle size that is desirably about five micrometers or less and preferably from about two to about three micrometers (.mu.m).
Rhenium metal powder and a refractory metal carbide powder are suitably converted to a powdered admixture by any one of a number of conventional mixing processes. The use of an attritor, wherein balls of a hard material, such as tungsten carbide/cobalt, are used to facilitate mixing, provides particularly satisfactory results.
The powdered admixture consists essentially of rhenium metal powder and a refractory metal carbide powder. In other words, no additional binder metal, such as cobalt, is needed. The rhenium metal powder is present in an amount within a range of from 1 to 25 percent by weight, based upon powdered admixture weight. The refractory metal carbide powder is present in an amount within a range of from 75 to 99 percent by weight, based upon powdered admixture weight. Desirable amounts of rhenium metal powder and refractory metal carbide powder are, respectively, from 5 to 20 and from 95 to 80 percent by weight of composition. Preferred amounts of rhenium metal powder and refractory metal carbide powder are, respectively, from 6 to 18 and from 94 to 82 percent by weight of composition. The amounts of rhenium metal powder and refractory metal carbide powder total 100 percent.
Mixing of the powders
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Gulau Ann M.
Timm Edward E.
Mai Ngoclan
The Dow Chemical Company
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