| 摘要 |
A method for altering the surface of a metal is provided with which it is possible to obtain a metallic product excellent in terms of surface hardness, heat resistance, corrosion resistance, resistances to high-temperature oxidation, high-temperature corrosion, and environmental corrosion, and other property. A base that is an iron-based metal or nickel-based metal is subjected to a halogenation treatment in which the base is heated and held in an atmosphere comprising a halogen-based gas, subsequently to a nitriding treatment in which the halogenated base is heated and held in an atmosphere comprising a nitriding gas, and then to a chromizing treatment in which the nitrided base is heated and held in a powder comprising a chromium metal powder, thereby forming a surface alteration layer in the base material. The metallic product obtained shows extremely high hardness, is excellent in terms of heat resistance and corrosion resistance, and exhibits excellent performance in environments which may cause high-temperature oxidation, high-temperature corrosion, erosion, cavitation, etc. The metallic product exhibits excellent performance even in acidic or alkaline environments, neutral environments, and corrosive environments including chlorides, such as seawater. |
