Method of producing refractory moulds for precision casting

摘要

993,161. Making refractory moulds. SOC. DES FORGES ET ATELIERS DU CREUST. April 11, 1962 [Sept. 11, 1961], No. 13967/62. Heading B5A. A method of making refractory moulds for precision casting comprises the steps of applying, in sequence, a contact coating, a primary coating and at least one reinforcing coating to a wax pattern or group of interconnected patterns, each coating being applied in the form of an opaque slip which includes a siliceous binder and a powdered refractory material, each slip being thicker than that used for the previous coating, and each coating being sprinkled with a granular refractory material before the coating is dry, the refractory material sprinkled on the contact coating having a grain size of from 0.1 to 0.3 mm. Preferably the wax pattern is degreased before coating, and the slip for the contact coating contains anti-drying, wetting and anti-foaming agents. The slip sets in air and is hardened by firing at 700‹ to 950‹ C. The binder may be colloidal silica or an ethyl silicate. The refractory material may be quartz, pure fused silica, alumina, zircon, zirconia, sillimanite, or ground burnt clay having a high alumina content. The grain size of the sprinkled material increases from coating to coating.