Water soluble cores, process for producing them and process for die casting metal using them

摘要

Disclosed are water soluble core wherein a particulate refractory material is combined with a binding agent comprising Na2CO3, Na2O . NSiO2 where n is 0.5 to 4, and SiO2 as ingredients and a process for producing the water soluble core. The process comprises mixing the particulate refractory material with a water glass, casting the mixture of the particulate refractory material and the water glass, hardening the casting by CO2 gas, and calcining the casting at between 100 DEG C. and a temperature less than that of an endothermic peak of the water glass in differential thermal analysis. Also, a process for die casting a metal is disclosed using the water soluble core which process comprises pre-heating the water soluble core from a temperature of 300 DEG C. below a melting point of the metal to a temperature of the endothermic peak.