Sintering Aids in Powder Metallurgy THE ROLE OF THE PLATINUM METALS IN THE ACTIVATED SINTERING OF REFRACTORY METALS

When a metallic powder is subjected to a suffkiently high pressure a certain amount of adhesion takes place between individual particles. If this compact i s then sintered the bond is improved by diflusion and intergranular grain growth. The earliest known platinum objects were fabricated by such a powder metallurgical process, and when European scientists first addressed the problem of manufacturing platinum bars they also used powder metallurgy to Overcome their inability to melt the metal. N o w powder metallurgical methods are widely used for fabricating a variety of materials, and this paper reviews studies made of the sintering of refractory metals when this process is promoted by the addition of a minor amount of a platinum group metal activator.