GB746867A - Improved method and apparatus for producing refractory articles and articles so produced - Google Patents

Abstract

Refractory articles are made by mixing powdered refractory material with at least 0,5 per cent of a binder of iron, nickel, cobalt or chromium metal, placing the mix in a mould, hot pressing at above 1150 DEG C. to form a skeleton in the presence of a liquid phase of the binder while maintaining a uniform and interconnected pore volume of 10 to 50 percent by volume of the skeleton, and then infiltrating the skeleton with a molten heat resistant metal or alloy of a melting point above 1100 DEG C. Specified materials are the nitrides, carbides, borides and silicides of titanium, zirconium, chromium, tungsten, columbium, molybdenum, vanadium and tantalum, the oxides of beryllium, magnesium, aluminium and zirconium, silicon carbide and boron carbide. The skeleton may be sintered before infiltration in a neutral, reducing or inert atmosphere. Mixtures exemplified for the skeleton are, in per cent by weight, tungsten carbide 70, titanium carbide 25 and cobalt 5; tungsten carbide 45, titanium carbide 25, chromium carbide 25 and cobalt 5: the composition disclosed in Specification 715,704 viz, titanium carbide 95, chromium carbide 5 and nickel 10 (relative to the sum of the carbides). Specified infiltrants are iron, nickel, cobalt, and their alloys with each other or with chromium, molybdenum, tungsten, vanadium, columbium and tantalum, e.g. cobalt 69, chromium 25, molybdenum 6; cobalt 52, chromium 28, nickel 11, and tungsten 9; nickel 60, molybdenum 16, chromium 14, tungsten 5, and iron 5; chromium 60, molybdenum 25 and iron 15; nickel 80, chromium 13-14 and iron 6-7, iron 70 and chromium 30; cobalt 59,6, chromium 23, nickel 10, tungsten 7, carbon 0,4; nickel 80 and chromium 20.ALSO:Refractory articles comprised substantially of a refractory material having a Vickers hardness of at least 750Kgs./m.m.2 and a melting point higher than 1535 DEG C. are made by mixing the material, as a powder, with at least 0.5 per cent of a binder of iron, nickel, cobalt or chromium metal, placing the mix in a mould, hot pressing at above 1150 DEG C to form a skeleton in the presence of a liquid phase of the binder while maintaining an uniform and interconnected pore volume of 10-50 per cent by volume of the skeleton and then infiltrating the skeleton with a molten heat resistant metal or alloy of a melting point above 1100 DEG C. Specified materials are the nitrides, carbides, borides and silicides of titanium, zirconium, chromium, tungsten, columbium, molybdenum, vanadium and tantalum, the oxides of beryllium, magnesium, aluminium and zirconium, silicon carbide and boron carbide. Sintering, in a neutral, reducing or inert atmosphere may be effected before infiltration.