Matériau métallique composite

摘要

A material for crucibles to contain molten glass, salts or oxides comprises three layers of metal joined by known methods of cladding, and comprising an inner layer of pure platinum which contacts the molten material, an outer layer of a platinum-rhodium alloy which is at least one-tenth of a millinetre thick, and a central layer formed of a platinum alloy which offers resistance to penetration by agents derived from the molten material which corrode platinum and/or a platinum alloy having high mechanical strength at high temperature. The outer layer may contain 10-30% rhodium to give increased resistance to atmospheric oxidation and increased creep-strength. The central layer may be an alloy containing 15-20% iridium which provides creep-strength and constitutes an obstacle to inter-granular penetration by lead, antimony and arsenic. Alternatively, the central layer may contain 13% ruthenium.