| 摘要 |
PROBLEM TO BE SOLVED: To improve mechanical strength and heat resistant temperature of a core by a method wherein a specified amount of a fine powder made of a heat resisting substance is uniformly mixed with a mixed solution prepared by adding polyvinyl alcohol and its eutectic compound of urea. SOLUTION: The uniform mixture of 30-70 pts.wt. of a dine powder made of a heat resisting substance to a mixed solution prepared by adding polyvinyl alcohol and its eutectic component to urea is used as a blow molding core 2 in a gravity casting mold 1 of a low melting metal. Then, after molding, the core 2 is eluted with hot water so as to obtain a low melting metal cast article 3. Further, the eutectic compound facilitates the casting at the formation of the core, without impairing the strength and water-solubility of the core, through it somewhat lowers the melting point and solidification point of urea containing polyvinyl alcohol. Benzoic acid, benzene sulfinate, benzene sulfonate chloride, barium salt, sulfuric acid, benzoic chloride, glycine, naphthalene, glutaric acid or the like is used as the eutectic compound. |
