Preferentially binder enriched cemented carbide bodies and method of manufacture
AssigneeKennametal Inc.
InventorsBela J. Nemeth, George P. Grab
Life of this patent
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Abstract
Cemented carbide substrates having substantially A or B type porosity and a binder enriched layer near its surface are described. A refractory oxide, nitride, boride, and/or carbide coating is deposited on the binder enriched surface of the substrate. Binder enrichment is achieved by incorporating Group IVB or VB transition elements. These elements can be added as the metal, the metal hydride, nitride or carbonitride.
Claims35
A cemented carbide body formed by sintering a substantially homogeneous mixture of constituents comprising:
- a least 70 weight percent tungsten carbide;
- a metallic binder;
- a metal carbide selected from the group consisting of the Group IVB and VB transition metal carbides;
- said metal carbide being present in an amount less than the amount of tungsten carbide;
- said body having substantially A to B type porosity throughout said body;
- said metal carbide combined with said tungsten carbide forming a solid solution carbide;
- a layer of at least partially solid solution carbide depleted material near a peripheral surface of said body.
A cemented carbide body formed by sintering a substantially homogeneous mixture of constituents comprising:
- at least 70 weight percent tungsten carbide;
- a cobalt binder alloy;
- a metal carbide selected from the group consisting of the Group IVB and VB transition metal carbides;
- said metal carbide combined with said tungsten carbide forming a solid solution carbide;
- a layer of at least partially solid solution depleted material near a peripheral surface of said body;
- and wherein said cobalt binder alloy has an overall magnetic saturation value of less than 158 gauss-cm.sup.3 /gm cobalt.
A cemented carbide body comprising:
- at least 70 weight percent tugnsten carbide;
- cobalt;
- a metal carbide selected from the group consisting of the group IVB and VB transition metal carbides;
- a layer of cobalt enrichment near a peripheral surface of said body;
- said body having substantially A to B type porosity throughout.
The product prepared by the process of forming a binder enriched layer near a peripheral surface of a substantially A to B type porosity cemented carbide body, in which said process comprises:
- milling and blending a first carbide powder, a binder alloy powder and a chemical agent powder selected from the group consisting of metals, alloys, nitrides and carbonitrides of Group IVB and VB transition metals;
- pressing a compact utilizing said powders;
- sintering said compact at a temperature above the binder alloy melting temperature so as to transform, at least partially, the chemical agent to a carbide in the layer to be binder enriched;
- removing said binder enriched layer in selected areas of said product;
- resintering said compact at a temperature above the binder alloy melting temperature so as to transform, at least partially, the chemical agent to a carbide in the layer near the peripheral surface of the selected area of the product.
A process for forming a cobalt binder enriched layer near a peripheral surface of a substantially A type porosity cemented carbide body, said process comprising the steps of:
- milling and blending powders comprising tungsten carbide, cobalt and a metal compound selected from the group consisting of nitrides, and carbonitrides of Group IVB and VB transition metals;
- pressing a compact utilizing said powders;
- sintering said compact at a temperature above the melting temperature of said binder so as to transform, at least partially, the metal compound to a metal carbide in the layer to be binder enriched.
Dependencies are inferred from the claim text.