| 摘要 |
536,857. Denture and like moulds. TITANIUM ALLOY MANUFACTURING CO. March 27, 1940, No. 5541. Convention date, March 31, 1939. [Class 22] Refractory moulds for casting metal articles such as dentures contain a material which will expand at high temperature as the result of oxidation such as carbon or nitrogen containing compounds of zirconium, titanium, thorium, cerium, hafnium and silicon. Examples of compounds are the carbide, nitride, oxycarbide or cyanonitride of zirconium, the carbide, nitride or cyanonitride of titanium, the carbide of silicon, thorium, cerium or hafnium or the nitride of thorium or hafnium. The amount of the expanding material added is regulated by the amount of expansion desired. A small amount of an oxidizing agent such as red lead or lead peroxide may be added. Impurities such as carbon, carbides of the alkali or alkaline earth metals and iron compounds should be removed by acid leaching. The refractory material used may be zircon, aluminium oxide. silica, quartz, rutile. fused zirconium dioxide, mullite, sillimanite, olivine, forsterite, chromite, refractory clay, kaolin, beryl, spinel, kyanite, thorium oxide, thorite, ceria, feldspar, andalusite, talc, baddeleyite, or porcelain and a bonding agent such as magnesium zirconate, phosphoric acid or water may be used. |
