MANUFACTURE OF EXOTHERMIC SELF-HARDENING WATER-SOLUBLE MOLD

摘要

PURPOSE:To extend usable time of mold material in molding an exothermic self-hardening water-soluble mold made of alumina sand using sodium aluminate and Al powder as binder by cooling the alumina sand and mixing in gaseous CO2 atmosphere. CONSTITUTION:An exothermic self-hardening water-soluble mold is molded by adding 3-10 weight parts sodium aluminate having Na2O/Al2O3 molar ratio of 1.5-3.0 and >=60% water and 0.3-1.0pt.wt. Al powder as binder to 100pts.wt. 65-150 mesh alumina sand of high purity. In this case, the alumina sand is cooled by mixing dry ice and sodium aluminate and Al powder are mixed as binder, or after cooling the alumina sand by mixing dry ice, sodium aluminate is mixed in CO2 atmosphere and blended with Al powder. Hardening reaction speed is retarded by sodium aluminate and Al powder and usable time can be extended.