Patent EA-001843-B1 (EA)
Title: A method for producing abrasive grains and the abrasive grains produced by this method
Inventor: GORDEEV SERGEY KONSTANTINOVICH
IPC: C04B35/573
Filed: 1998-09-03
Abstract: 1. A method for producing abrasive grains, characterised of manufacturing a polycrystalline body comprising diamond particles in a matrix of silicone carbide and silicon, the manufacture of the polycrystalline body comprises the steps of: forming a work piece from diamond particles, heating the work piece and temperature and heating time control so as to determine that the required amount of graphite is produced due to graphitization of diamond particles resulting to produce semi-product and infiltration of the obtained semi-product with silicon after which the polycrystalline body are crushed into grains. 2. The method according to claim 1, characterised by manufacturing a polycrystalline body comprising 20-70 vol.-% of diamond particles, 0.1-75 vol.-% of silicon carbide and 1-40 vol.-% of silicon, and crushing the polycrystalline body into grains. 3. The method according to claim 2, characterised by the steps of manufacturing a polycrystalline body comprising at least 20 vol.-% of diamond particles, at least 5 vol.-% of silicon carbide, preferably more than 15 vol.-% of silicon carbide, and silicon, the Young's modulus exceeding 450 GPa, and crushing the polycrystalline body into grains. 4. The method according to claim 3, characterised by the steps of manufacturing a polycrystalline body comprising at least 29 vol.-% of diamond particles, at least 14 vol.-% of silicon carbide, and silicon, the Young's modulus exceeding 540 GPa, and crushing the polycrystalline body into grains. 5. The method according to claim 3, characterised by the steps of manufacturing a polycrystalline body comprising at least 46 vol.-% diamond particles having sizes of about 30 (m at the most, at least 5 vol.-% of silicon carbide, preferably more than 15 vol.-% of silicon carbide, and silicon, the Young's modulus exceeding 560 GPa, and crushing the polycrystalline body into grains. 6. The method according to claim 3, characterised by the steps of manufacturing a polycrystalline body comprising at least 54 vol.-% of diamond particles, at least 60% of the diamond particles having sizes of at least 50 (m, at least 5 vol.-% of silicon carbide, preferably more than 15 vol.-% of silicon carbide, and silicon, the Young's modulus exceeding 650 GPa, and crushing the polycrystalline body into grains. 7. The method according to any one of claims 1-6, characterised by crushing the polycrystalline body into grains having a size of at least 40 mkm. 8. The method according to any one of claims 1-7,characterised by forming the work piece of diamond particles having a size of 3-500 (m. 9. The method according to any one of claims 7-9, characterised in that the amount of graphite created during the heat treatment of the work piece is 1-50 wt-%, preferably 6-30 wt-% of the amount of diamond. 10. The method according to any one of claims 7-10, characterised in that the heating temperature during graphitization is lower than 1700 degree C. 11. The method according to any one claims 7-11, characterised in that the heating temperature and heating time needed for the graphitization is empirically determined for the heating equipment used. 12. The method according to any one of claims 7-12, characterised by forming the work piece with a porosity of 25-60 vol.-%. 13. The method according to any one of claims 7-13, characterised by depositing a certain amount of carbon on the work piece by exposing the work piece to a gaseous hydrocarbon or hydrocarbons at a temperature exceeding the decomposition temperature for the hydrocarbon or hydrocarbons. 14. The method according to claim 13, characterised in that at least some graphitization of the diamond particles is carried out before the work piece is exposed to a gaseous hydrocarbon or hydrocarbons at a temperature exceeding the decomposition temperature for the hydrocarbon or hydrocarbons. 15. The method according to any one of claims 7-15, characterised in that the work piece is formed from a homogeneous mixture of diamond particles of various sizes eventually with the addition of a binder. 16. The method according to any one of claims 7-16, characterised in that the forming of the work piece is made in a mould, the heat treatment and the infiltration of silicon being made after the work piece has been taken out of the mould. 17. Abrasive grains according to claim 1, characterised in that the grains comprise 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. 18. Abrasive grains according to claim17, characterised in that the mean value content of diamond particles, silicon carbide and silicon in the grains being at least 20, at least 5, and 1-40 vol.-%, respectively. 19. Abrasive grains according to claim 17, characterised in that the mean value content of diamond particles, silicon carbide and silicon in the grains being at least 29, at least 14, and 140 vol.-%, respectively. 20. Abrasive grains according to claim 17, characterised in that the mean value content of diamond particles, silicon carbide and silicon in the grains being at least 46, at least 5, and 1-40 vol.-%, respectively, the diamond particles having sizes of about 30 μm or less. 21. Abrasive grains according to claim 17, characterised in that the mean value content of diamond particles, silicon carbide and silicon in the grains being at least 54, at least 5, and 1-40 vol.-%, respectively, at least 60% of the diamond particles having sizes of at least 50 μm. 22. Abrasive grains according to any one of claims 17-21, characterised in that the diamond particles in the grains have a size of 3-500 (m. 23. Abrasive grains according to any one of claims 17-21, characterised in that the grains have a thermal stability factor less than 1.2, preferably less than 1.1.