METHOD FOR IMPROVING ENVIRONMENTAL RESISTANCE OF INVESTMENT CAST CEMENTED CARBIDE ARTICLE

摘要

PROBLEM TO BE SOLVED: To remove sulfur from a cemented carbide article by performing the heat treatment while the compound containing elements forming sulfide is brought into contact with a surface of the cemented carbide article, and separating the sulfide formed on the surface of the cemented carbide article. ;SOLUTION: A face coat 12 containing elements forming sulfide is provided on a surface of a mold 10. A compound containing the elements forming the sulfide is at least one compound to be selected among the group comprising yttria, calcium oxide, magnesia, scandia, ceria, hafnia, zirconia, titania, lanthania, alumina, and silica. The face coat 12 is ≥0.3mm in thickness. The face coat is applied to the surface of a core 16. The molten cemented carbide is poured in a cavity of the mold to cast a parts 14. The parts 14 is heat treated at the solution heat treatment temperature in the atmosphere to be selected from among the group comprising the partial pressure of vacuum, hydrogen- containing gas, and argon. Sulfur in the parts 14 is segregated on the surface, and reacted with the face coat 12 to be oxisulfide and removed.;COPYRIGHT: (C)1997,JPO