REFRACTORY MATERIAL FOR ALUMINUM-LITHIUM ALLOY

PURPOSE:To obtain stabilized refractory material by adding a specified amount of magnesia to alumina containing a certain amount of boric anhydride, thus being prevented from the penetration of aluminum-lithium alloy melt into the refractory material. CONSTITUTION:The refractory material for aluminum-lithium alloy comprises 5 to 20wt.% of magnesia, 0.5 to 5wt.% of boric anhydride and the residue of alumina. The addition of less than 5wt.% of magnesia is insufficient against the penetration of Li into the boundary areas of the textures, while over 20wt.% have the possibility of cracking because of its excessive increase in linear expansion coefficient. Boric anhydride mainly acts as a binder to harden the material into high stiffness, but it reacts with Li to form high-melting 2Li2O, B2O3 or Li2O, B2O3. These products migrate on the surfaces of the refractory material to form viscous, and thin coating films, thus protecting the material from the penetration of the aluminum-lithium melt.