PRODUCTION OF CORE FOR CASTING LIGHT ALLOY

摘要

PURPOSE:To obtain a core for casting a light alloy with which the stripping of a film does not arise in the stage of casting by hardening molding sand with a binder and molding the sand then coating water glass emulsified with Al2O3 powder and Al powder thereon and calcining the sand thereby adhering the heat resistant film thereto. CONSTITUTION:A binder of a thermosetting resin or a resin curable by chemical reaction is mixed with molding sand and a core 1 is molded and hardened. Water glass mixed and emulsified with Al2O3 powder and Al powder is coated on the surface of the core 1 to form a mold coating material layer 2 and to penetrate part thereof in the surface layer part of the core 1, thereby forming a penetrated layer 1a. Such molding sand is calcined at 300-400 deg.C to stack and adhere the Al2O3 powder and the half molten Al in the layer 1a and the layer 2 and on the surface and surface layer part of the core 1, thus forming a tough and strong air permeable film having heat resistance. The sand and metal penetration in the stage of casting such as die casting of a light alloy is prevented by using such core.