GB667219A - Improvements in or relating to the manufacture of moulds and moulded articles - Google Patents

Abstract

667,219. Powder metallurgy; making dies and turbine blades. PENRICE, T. W., and KNOWLSON, R. F. Aug. 30, 1950 [Sept. 12, 1949], No. 23546/49. Classes 83 (ii) and 83 (iv). [Also in Group V] In a method of making articles from metal powders a mould is first prepared by impressing a master shape in a powder-mass comprising a refractory metal, carbide, nitride or boride, or other powder capable of being sintered, partially sintering the mass by heat and pressure and removing the master shape. Metal powder is then introduced into the mould and compressed and sintered at such a pressure and temperature as to cause no further compacting of the mould. Any mould material adhering to the sintered article may be removed as by shot blasting. In an example, a master shape made from compressed carbon is impressed into a mass of titanium carbide powder by the application of pressure at a temperature of between 1600- 2000‹ C., a partially sintered mould being obtained. This mould is filled with a mixture of tungsten carbide and cobalt powders which is compacted at the same pressure as that used for shaping the mould and sintered at a lower temperature of 1350-1450‹ C. A five-grain titanium carbide powder could be sintered in a mould of coarser titanium carbide using a lower sintering temperature of 1450-1600‹ C. As applied to the making of a turbine blade, a mould is formed by a graphite pattern from titanium carbide powder using a pressure of three tons per square inch and a temperature of 2000‹ C. Powder consisting of titanium carbide containing 20 per cent by weight of cobalt was introduced into the mould and sintered at 1450‹ C. under a pressure of three tons per square inch. The mould was then removed by mechanical abrasion. The titanium carbide could be replaced by the metal itself or by its nitride, boride or oxide or mixtures thereof.