Patent EA-002903-B1 (EA)
Title: Tough-coated hard powders and sintered articles thereof
IPC: B22F1/18
Filed: 1998-05-13
Abstract: 1. A sintered material comprising: a plurality of core particles, said core particles consisting essentially of a first metal compound having the formula MaXb where M is a metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, aluminum, and silicon, X represents one or more elements selected from the group consisting of nitrogen, carbon, boron and oxygen, and a and b are numbers greater than zero up to and including four; an intermediate layer on each of said core particles, said layer consisting essentially of a second metal compound, different in composition from said first metal compound and having a higher relative fracture toughness, said second metal compound being capable of bonding with said first metal compound and being capable of bonding with a metal selected from the group consisting of iron, cobalt and nickel, thereby forming coated particles; and a binder overlaying said intermediate layer on said coated particles, said outer layer comprising iron, cobalt, nickel, their mixtures, their alloys or their intermetallic compounds. 2. The sintered material of Claim 1, said coated particles having an average particle size less than about 2μm. 3. The sintered material of Claim 1, said coated particles having an average particle size less than about 1μm. 4. The sintered material of Claim 1, said intermediate layer having a thickness, after sintering, in the range of from 5% to 25% of the diameter of said core particles. 5. The sintered material of Claim 1, said intermediate layer having a thickness such that strain fields associated with dislocations in one coated particle are transmitted through said intermediate layer to the immediately adjacent core particle. 6. The sintered material of Claim 1, said intermediate layer having a thickness, after sintering, in the range of from 3% to 200% of the diameter of said core particles. 7. The sintered material of Claim 1, said outer layer having a thickness after sintering in the range of from 3% to 12% of the diameter of said coated particles. 8. The sintered material of Claim 1, said outer layer having a thickness such that strain fields associated with dislocations in one coated particle are transmitted through said binder to the immediately adjacent intermediate layer. 9. The sintered material of Claim 1, wherein the said first metal compound consists essentially of a stoichiometric compound. 10. The sintered material of Claim 1, wherein the said first metal compound consists essentially of a metal compound selected from the group consisting of: TiN, TiCN, TiB2 TiC, ZrC, ZrN, VC, VN, Al2O3, Si3N4 and AIN. 11. The sintered material of Claim 1, wherein the said second metal compound consists essentially of a metal compound selected from the group consisting of: WC and W2C. 12. The sintered material of Claim 1, wherein portions of said intermediate layer and said binder are removed to expose the interior of said core particles. 13. The sintered material of Claim 1, wherein said sintered material has a fracture toughness greater than cubic boron nitride. 14. A sintered material comprising: a plurality of core particles, said core particles consisting essentially of a metal compound selected from the group consisting of:TiN, TiCN, TiB2, TiC, ZrC, ZrN, VC, VN, Al2O3, Si3N4 and AIN; an intermediate layer on each of said core particles said layer consisting essentially of a second metal compound, different in composition from said first metal compound and having a higher relative fracture toughness, said second metal compound consisting essentially of WC; and a binder overlaying said intermediate layer on said coated particles, said binder comprising cobalt or nickel. 15. A sintered material comprising: a plurality of core particles, said core particles consisting essentially of a plurality of metal compounds, each having the formula MaXb where M is a metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, aluminum and silicon, X represents one or more elements selected from the group consisting of nitrogen, carbon, boron and oxygen and a and b are numbers greater than zero up to and including four; an intermediate layer on each of said core particles said layer consisting essentially of a different metal compound, different in composition from said plurality of said metal compounds forming said core particles and having a higher relative fracture toughness, said different metal compound being capable of bonding with said metal compounds forming said core particles and being capable of bonding with a metal selected from the group consisting of iron, cobalt and nickel, thereby forming coated particles; and a binder overlaying said intermediate layer on said coated particles, said binder comprising iron, cobalt, nickel, their mixtures, their alloys or their intermetallic compounds. 16. The sintered material of Claim 15, said coated particles having an average particle size less than about 2μm. 17. The sintered material of Claim 15, said coated particles having an average particle size less than about 1μm. 18. The sintered material of Claim 15, said intermediate layer having a thickness, after sintering, in the range of from 5% to 25% of the diameter of said core particles. 19. The sintered material of Claim 15, said intermediate layer having a thickness such that strain fields associated with dislocations in one coated particle are transmitted through said intermediate layer to the immediately adjacent core particle. 20. The sintered material of Claim 15, said intermediate layer having a thickness, after sintering, in the range of from 3% to 200% of the diameter of said core particles. 21. The sintered material of Claim 15, said outer layer having a thickness such that strain fields associated with dislocations in one coated particle are transmitted through said outer layer to the immediately adjacent intermediate layer. 22. The sintered material of Claim 15, wherein said metal compounds forming said core particles consists essentially of stoichiometric compounds. 23. The sintered material of Claim 15, wherein said metal compounds forming said core particles consist essentially of a metal compounds selected from the group consisting of: TiN, TiC N, TiB2, TiC, ZrC, ZrN, VC, VN, Al2O3, Si3N4 and AIN. 24. The sintered material of Claim 15, wherein the said different metal compound consists essentially of WC. 25. The sintered material of Claim 15, wherein portions of said intermediate layer and said binder are removed to expose the interior of said core particles. 26. The sintered material of Claim 15, wherein said sintered material has a fracture toughness greater than cubic boron nitride. 27. A sintered material comprising: a plurality of core particles consisting essentially of cubic boron nitride; an intermediate layer on each of said core particles said layer consisting essentially of WC said intermediate layer having a thickness, after sintering, in the range of from 5% to 25% of the diameter of said core particles; and a binder comprising iron, cobalt, nickel, their mixtures, their alloys or intermetallic compounds overlaying said intermediate layer, said binder having a thickness after sintering in the range of from 3% to 12% of the diameter of said coated particles, the combination of said core particles, said intermediate layer and said binder forming a coated particle. 28. The sintered material of Claim 27, said coated particles having an average particle size less than about 1μm. 29. A powder consisting essentially of a plurality of coated particles, the majority of said coated particles having: core particles consisting essentially of a first metal compound having the formula MaXb where M is a metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, aluminum and silicon, X represents one or more elements selected from the group consisting of nitrogen, carbon, boron and oxygen and a and b are numbers greater than zero up to and including four; and an intermediate layer on each of said core particles, said layer consisting essentially of a second metal compound, different in composition from said first metal compound and having a higher relative fracture toughness, said second metal compound being capable of bonding with said first metal compound and being capable of bonding with a metal selected from the group consisting of iron, cobalt and nickel. 30. The powder of Claim 29, said coated particles having an average particle size of less than about 2μm. 31. The powder of Claim 29, said coated particles having an average particle size of less than about 1μm. 32. The powder of Claim 29, said layer having a thickness in the range of from 5% to 25% of the diameter of said core particles. 33. The powder of Claim 29, said intermediate layer having a thickness, after sintering, in the range of from 3% to 200% of the diameter of said core particles. 34. The powder of Claim 29, wherein the said first metal compound consists essentially of a stoichiometric compound. 35. The powder of Claim 29, wherein the said first metal compound consists essentially of a metal compound selected from the group consisting of: TiN, TiCN, TiB2, TiC, ZrC, ZrN, VC, VN, Al2O3, Si3N4 and AIN. 36. The powder of Claim 29, wherein the said second metal compound consists essentially of WC or W2C. 37. The powder of Claim 29, including an outer binder layer consisting essentially of a metal selected from the group consisting of: iron, cobalt, nickel, their mixtures, their alloys or their intermetallic compounds, said binder layer being deposited on the outer surface of said second metal compound layer in the form of a continuous layer. 38. The powder of Claim 37, wherein said continuous layer of binder is deposited by chemical vapor deposition,