GB827016A - Improved method of producing metal coated, non-metallic particles - Google Patents

Abstract

Non-metallic particles are coated with Os, Rh, Ru, Ir, Pt, Pd, Au, Ag, Cu, As, Pb, Sn, Ni or Co by being dispersed in an ammoniated solution containing a soluble compound of one of said metals, and reacting the solution with a reducing gas at a temperature above 200 DEG F. and under a positive partial pressure of reducing gas. The resulting powder may be compacted to form high temperature alloys, cermets and ceremels. The non-metallic particles may be oxides, such as those of Al, Be, Th, Zr, Ti, Si, Ce, Cr, U, V; oxide combinations with calcium oxide such as the Spinel group; sulphides, such as those of Ce, Th, U; and carbon in its crystal forms. The ammoniated solution may be aqueous or other solvents such as alkanols, ethers, ketones and esters may be used. The soluble compound of the metal may be the sulphate, chloride, nitrate, carbonate, fluosilicate or acetate. Hydrogen is preferred as the reducing gas; other gases that may be used are carbon monoxide, methane, producer gas and natural gas. The reaction is preferably conducted at a temperature of 200 DEG F.-500 DEG F. and under a partial pressure of reducing gas of 4-35 atmospheres. Prior to coating with metals other than Ag and Cu, the refractory particles should be impregnated with an agent which has a higher reducing potential under reducing conditions than the reducing gas employed so that the metal deposits on the particles as an adherent coating; suitable agents are ferrous, thorous, cerous, manganous and chromous compounds, hydrophosphites, hydrosulphides, hydrosulphites, hydrazine, formaldehyde, phosphites, cyanides, formates, thiosulphates, nitrites, sulphites and sulphides. Specification 824,092 is referred to.