EXTRAHARD MATERIAL OF HEXAGONAL STRUCTURE BASED ON METAL CARBIDES, A METHOD FOR ITS PREPARATION AND ITS USE AS A CATALYST OR FOR SINTERED CARBIDE PRODUCTS

摘要

PCT No. PCT/EP78/00004 Sec. 371 Date Apr. 9, 1979 Sec. 102(e) Date Apr. 5, 1979 PCT Filed Jul. 27, 1978 PCT Pub. No. WO79/00089 PCT Pub. Date Feb. 22, 1979. A process for the preparation of an extrahard material based on tungsten and molybdenum carbides and having a hexagonal crystal structure identical with that of tungsten carbide. According to this process, one heats between 1000 DEG C. and a temperature Tx, which is lower than the maximum stability limit of the MoxWl-xC phase wherein 0.01x1, a mixture, intimate to the molecular or atomic scale, of tungsten and molybdenum the total content of which in Fe, Ni and Co does not exceed 0.1% with carbon and/or a carbon compound. Tx is defined as follows: For 0.01x0.8, Tx=2700-1375x DEG C; For 0.8x1, Tx=3400-2250x DEG C.