GB442773A - Improvements in comminuted alloys - Google Patents

Abstract

Comminuted alloys of the type suitable for the production of dental amalgams consist of particles having dimensions varying essentially between about 0,01 and 0,1 mm, and having the thickness about one third the length. The particles may be made by cutting preferably tubular ingots of the alloy into chips, grinding the chips in a ball, rod, or cone mill, sorting the resulting granules by elutriation and annealing them. During the casting and until cold the alloy is protected by a reducing atmosphere, and the cutting, and preferably also the grinding, is done under a liquid. The subsequent annealing is done under a solution which may be an aqueous solution of a reducing agent. The particles so obtained have smooth convex surfaces and are free from cracks. The alloy may consist mainly of silver with smaller amounts of tin and copper, particularly not less than 65 per cent of silver, not less than 25 per cent of tin, not more than 6 per cent of copper, and not more than 2 per cent of zinc, with or without small amounts of other metals such as beryllium, gallium, indium, germanium and palladium.