Water soluble ceramic core for use in die casting, gravity and investment casting of aluminum alloys

摘要

A water-soluble ceramic core is prepared which can be advantageously used in the die casting, gravity casting, and investment casting of precision aluminum alloy objects. The ceramic core contains: (a) 60 to 70% by weight of alumina (A1.sub.2 O.sub.3) flour; (b) about 15 to 25 by weight of zircon (ZrSiO.sub.4) flour; (c) about 5 to 15 by weight of sodium hydrogen phosphate (Na.sub.2 HPO.sub.4); and (d) about 5 by weight of sugar. In preparing the ceramic core, sodium hydrogen phosphate and sugar are first dissolved in water to form a sodium hydrogen phosphate/sugar solution. Then alumina flour and zircon flour are added into the sodium hydrogen phosphate/sugar solution to form a slurry, which is caused to form a precursory ceramic core using an injection molding or slip casting process. After blow-drying the precursory ceramic core is calcined at temperatures between 70 and 800. degree. C. The ceramic core can be optionally immersed into a lacquer solution to impart a water- proof film on its surface, so as to allow it to withstand attacks from steam during autoclaving.