Alumina forming high temperature silicides and carbides

Aluminium containing heat-resistant silicides and ternary carbides (Maxthal®), have been evaluated in terms of their high temperature behaviour in various atmospheres including vacuum. The novelty of these materials is in their ability to form a stable and adherent protective alumina scale at low partial pressures of oxygen as well as in air. Recently developed heating elements, for oxidising and reducing atmospheres, made of molybdenum aluminosilicide (Kanthal Super ER) have been evaluated by thermogravimetric analysis (TGA) studies in air and other atmospheres. The performance up to 1575 °C has been evaluated at vacuum levels down to 10−4 mbar. In addition to its remarkable thermal shock resistance, damage tolerance and machinability, Ti2AlC (Maxthal®) showed a parabolic and stable oxide growth rate up to 1400 °C in air. Cyclic testing confirmed that the oxide layer is adherent to the bulk. It has been concluded that both Maxthal® and Kanthal Super ER are capable of operating in air, up to 1400 and 1575 °C, respectively.