Patent EA-003715-B1 (EA)
Title: Method of manufacturing a diamond composite and a composite produced by same
Inventor: GORDEEV SERGEY K
IPC: C22C26/00
Filed: 1999-03-04
Abstract: 1. A low-pressure method for manufacturing a diamond composite from diamond particles, comprising the steps of forming a work piece having a predetermined size and shape, heating the work piece and controlling the heating temperature and heating time so that a certain desired amount of graphite is created by graphitization of diamond particles, thereby creating an intermediate body, and infiltrating silicon alloy into the intermediate body, thereby creating a final body having the same predetermined size and shape as the work piece in a macroscopic scale. 2. The method according to Claim 1, wherein the method steps are performed under a pressure below 50 bars, preferably below 30 bars, and more preferably below 2 bars. 3. The method according to Claim 1 or 2, wherein the amount of graphite created by graphitization is 1-50 wt-%, preferably 6-30 wt-% of the amount of diamond. 4. The method according to any one of Claims 1-3, wherein the heating temperature during graphitization is lower than 1900 degree C, preferably lower than 1700 degree C. 5. The method according to Claim 4, wherein the heating temperature and heating time needed for the graphitization is empirically determined for the heating equipment used. 6. The method according to any one of Claims 1-5, wherein the work piece is formed with a porosity of 25-60 vol-%. 7. The method according to any one of Claims 1-6, wherein a certain amount of carbon is deposited in the work piece by exposing it to a gaseous hydrocarbon or gaseous hydrocarbons at a temperature exceeding the decomposition temperature for hydrocarbon or hydrocarbons. 8. The method according to Claim 7, wherein at least some graphitization of the diamond crystals is done before exposing the work piece to a gaseous hydrocarbon or gaseous hydrocarbons at a temperature exceeding the decomposition temperature for hydrocarbon or hydrocarbons. 9. The method according to Claim 7 or 8, wherein the intermediate body is machined into the desired shape and size of the final body before the step of infiltration of liquid silicon alloy. 10. The method according to Claim 1 or 2, wherein the intermediate body is heated in the presence of vaporous silicon or silicon alloy and then machined into the desired shape and size of the final body before the step of infiltration of liquid silicon alloy. 11. The method according to any one of Claims 1-10, wherein the work piece is formed with a non-uniform distribution of diamond particles with various sizes and qualities. 12. The method according to any one of Claims 1-10, wherein the work piece is formed from a homogeneous mixture of diamond particles of various sizes eventually with the addition of a binder. 13. The method according to any one of Claims 1-10, wherein the diamond particles in the work piece are distributed in successively decreasing sizes from the surface of the work piece towards the centre thereof. 14. The method according to any one of Claims 1-13, wherein two or more work pieces are made separately and thereafter being brought together before the heat treatment and the infiltration steps. 15. The method according to any one of Claims 1-8, 11-14, wherein the forming of the work piece is made in a mould, the heat treatment and the infiltration of silicon alloy being made after the work piece has been taken out of the mould. 16. The method according to any of Claims 1-15, wherein a silicon alloy comprising at least one element from the group consisting of metals Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Co, Ni, Cu, Ag, Al, and the elements B and Ge, is infiltrated into the intermediate body. 17. The method according to Claim 16, wherein the silicon alloy contains Ti, Zr, and/or Hf to a content of less than 50 wt-%, preferably less than 20 wt-%. 18. The method according to Claim 16, wherein the silicon alloy contains V, Nb, and/or Ta to a content of less than 20 wt-%, preferably less than 10 wt-%. 19. The method according to Claim 16, wherein the silicon alloy contains Cr and/or Re to a content of less than 45 wt-%, preferably less than 20 wt-%. 20. The method according to Claim 16, wherein the silicon alloy contains Mo and/or W to a content of less than 10 wt-%, preferably less than 5 wt-%. 21. The method according to Claim 16, wherein the silicon alloy contains Mn, Fe, Co and/or Ni to a content of less than 60 wt-%, preferably less than 20 wt-%. 22. The method according to Claim 16, wherein the silicon alloy contains Cu and/or Ag to a content of less than 30 wt-%, preferably less than 15 wt-%. 23. The method according to Claim 16, wherein the silicon alloy contains Al and/or Ge to a content of less than 50 wt-%, preferably less than 20 wt-%. 24. The method according to Claim 16, wherein the silicon alloy contains B to a content of less than 20 wt-%, preferably less than 8 wt-%. 25. A body in which diamond particles are bonded to a matrix of metal-silicon-carbon or boronsilicon-carbon phases, said body comprising at least 20 vol-% of diamond particles, at least 25 vol-% of metal-silicon-carbon or boron-silicon-carbon phases, preferably more than 35 vol-% of metal-silicon-carbon or boron-silicon-carbon phases, the Young's modulus exceeding 450 GPa. 26. A body according to Claim 25, said body comprising at least 29 vol-% of diamond particles, at least 34 vol-% of metal-silicon-carbon or boron-silicon-carbon phases, the Young's modulus exceeding 540 GPa. 27. A body according to Claim 25, wherein said body comprises at least 46 vol% of diamond particles having sizes of about 30 mum at the most, the Young's modulus exceeding 560 GPa. 28. A body according to Claim 25, wherein said body comprises at least 54 vol% of diamond particles, at least 60 % of the diamond particles having sizes of at least 50 mum, the Young's modulus exceeding 600 GPa. 29. A body according to Claim 25, wherein said metal-silicon-carbon or boronsilicon-carbon phases comprises silicon carbide, metal carbides, boron carbides, metal silicides, boron silicides, metal carbosilicides, alloys of metals with silicon, and silicon. 30. A body according to Claim 25-29, wherein said metal is at least one metal from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Co, Ni, Cu, Ag, Al, Ge. 31. A body according to any one of Claims 25-30, wherein the metal content does not exceed 30 wt-% and preferably is less than 20 wt-%. 32. A body according to Claim 31, wherein the metal is chosen from the group of V, Nb, Ta and the metal content is less than 10 wt-%. 33. A body according to Claim 31, wherein the metal is chosen from the group of Mo, W and the metal content is less than 5 wt-%. 34. A body according to any one of Claims 25-33, wherein the body maintains its shape and its Young's modulus after exposure to a temperature of 1500 degree C in vacuum. 35. A body according to Claim 25, wherein diamond particles of sizes of about 10 mum or less are embedded and included in the matrix, the Vickers hardness of the matrix measured in an area between diamond particles being greater than 30 GPa for a load of 20 N. 36. A body according to Claim 35, wherein diamond particles of sizes of about 10 mum or less are embedded and included in the matrix, the Knoop hardness of the matrix being greater than 30 GPa for a load of 20 N. 37. A body according to Claim 25, wherein the diamond particles have one size fraction of particles being larger than 50 mum and one sizes fraction of particles having a size of 50 mum at the most, the mass ratio falling in the range of 0.25 to 2.5 and the mean particle size being larger than 10mum, preferably larger than 20mum. 38. A body according to Claim 25, wherein the diamond particles have one size fraction of large diamond particles and one size fraction of small diamond particles, the mass ratio falling in the range of 0.25 to 2.5 and the mean particle size being larger than 10mum, preferably larger than 20 mum. 39. A body according to Claim 25, wherein the body is hollow. 40. A body according to Claim 25, wherein the body comprises large diamond particles of a size larger than 20 mum, the matrix comprising 0-50 vol-% of small diamond particles having sizes less than 20 mum; 20-99 vol-% of silicon carbide; and 1-30 vol-% of other metal-silicon-carbon or boron-silicon-carbon phases; the matrix hardness being 20-63 GPa. 41. A body according to Claim 40, wherein the matrix hardness is 20-30 GPa. 42. A body according to Claim 40, wherein the matrix hardness is 50-63 GPa. 43. A body according to Claim 40, wherein the matrix hardness is 30-50 GPa. 44. Abrasive grains manufactured by the method according to Claim 1, comprising diamond particles, silicon carbide and silicon, the diamond particles being placed in a matrix of silicon carbide and silicon, the mean value content of diamond particles, silicon carbide and silicon in the grains being 20 70, 0.1-75 and 1-40 vol.%, respectively.