| 摘要 |
PROBLEM TO BE SOLVED: To solve such problem that the restraint of penetration to a thick cast product is difficult and the formation of a sound coated layer is difficult though a surface improving method using a liquid-phase sintering is an effective means. SOLUTION: In the surface improving casting method in which mixed powder resulting from mixing metallic main powder A for giving a specified property, metallic sintering assistant agent powder B having lower melting point than that of the main powder and an organic base binder C, is stuck to a desired position in a cast product and the powders are mutually unified by the liquid- phase sintering generated among the above three materials to give the cast product the specified property, when the cast product is especially thick, at first, the mixed powder composed of the main powder A and the sintering assistant agent B is coated as a first layer on the surface of the mold and on the first layer used as a substrate, a second layer is overlaid to form a double layer structure. In the second layer, mixing ratio of the main powder A to the sintering assistant agent B is higher than in the first layer, and thus, the penetration of the main powder is restrained in spite of the thick cast product, and the minute improved layer having little pores can be formed.
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