| 摘要 |
PURPOSE:To obtain a cast iron casting of which the outside surface layer has superior abrasion resistance in centrifugal casting by separating by gravity the carbide powder having a specific gravity larger than that of the iron added to molten metal for casting and high hardness and abrasion resistance from said iron. CONSTITUTION:Powder to be added to molten metal for casting is carbide or double carbide, for example, WC powder. This is extremely vulnerable to reaction with the O2 in the atmospheric air and decomposition. Thereupon, as a measure for prevention of its oxidation, carbide is added to the molten metal in the state wherein it is settled in molten flux. The molten flux is preferably the one of the b.p. higher than the temp. of the molten metal (that is, of a low m.p., a high b.p., and low viscosity) at which carbide powder can be added at low temp., and it settles immediately in the bottom of the molten flux and is thereby prevented from oxidizing, and when it is teemed into the molten metal, it does not evaporate and foam. The molten metal mixed with this carbide is subjected to centrifugal casting, and the addition of the carbide is preferably just prior to casting. In this case, the cast iron casting formed with the carbide layer in one piece on the outside surface is obtained. |
