Patent GB-721622-A (GB)
Title: Compositions containing carbon boride and a metal boride
IPC: C22C29/00
Filed: 1952-06-17
Abstract: Solid refractory articles of carbon boride and metal boride are formed by heating to a temperature of at least 1900 DEG C. under pressure of at least 1000 p.s.i., a mixture of boron-rich boron carbide having more boron than is represented by B4C, and metal selected from the group consisting of titanium, vanadium, chromium, zirconium, columbium, molybdenum, hafnium, tantalum and tungsten and mixtures thereof, wherein the amounts of said metal and said boron carbide, are selected in such proportion on the assumption that the metal will be converted wholly to its boride, that the metal boride will constitute 10-15 per cent by volume of the article formed, regarding for the purpose of calculation, the article as one consisting solely of metal boride and boron carbide B4C.  According to an example in the preparation of an article composed of titanium boride, TiB2 and B4C, a boron-rich boron carbide having 81 per cent boron and a titanium powder are selected in such proportions to provide 16.1 per cent by volume or 23.2 per cent by weight of TiB2. The mixture is thoroughly ground, placed in a graphite mould under 2500 p.s.i. pressure and the mould placed in a furnace heated to 2200 DEG C. for half an hour.  The final article should not contain more than 3.1 per cent of carbon based on the B4C remaining nor more than 4 per cent by weight of metal carbide calculated on the weight of the article.  Preferably at least 80 per cent by weight of the material in the final article other than metal boride should be carbon boride. The method is suitable for the production of dies, gauge tips and blocks, mortars and sand-blast nozzles and for truing grinding wheels.  The final material has a hardness exceeding 9 on Moh's scale.ALSO:Solid refractory articles of carbon boride and metal boride are formed by heating to a temperature of at least 1900 DEG C. under pressure of at least 1000 p.s.i., a mixture of boron-rich boron carbide having more boron than is represented by B4C, and metal selected from the group consisting of titanium, vanadium, chromium, zirconium, columbium, molybdenum, hafnium, tantalum and tungsten and mixtures thereof, wherein the amounts of said metal and said boron carbide, are selected in such proportion, on the assumption that the metal will be converted wholly to its boride, that the metal boride will constitute 10-50 per cent. by volume of the article formed, regarding for the purpose of calculation, the article as one consisting solely of metal boride and boron carbide B4C.  According to an example in the preparation of an article composed of titanium boride, TiB2 and B4C, a boron-rich boron carbide having 81 per cent boron and a titanium powder are selected in such proportions to provide 16.1 per cent by volume or 23.2 per cent by weight of TiB2. The mixture is thoroughly ground, placed in a graphite mould under 2500 p.s.i. and the mould placed in a furnace heated to 2200 DEG C for half an hour.  The final article should not contain more than 3.1 per cent of carbon based on the B4C remaining nor more than 4 per cent by weight of metal carbide calculated on the weight of the article.  Preferably at least 80 per cent by weight of the material in the final article other than metal boride should be carbon boride.