| 摘要 |
PURPOSE:To enhance the corrosion resistance of steel parts in a corrosive atmosphere at high temp., by depositing Ni and Cr on the surfaces of the parts in a vapor phase and by cementation. CONSTITUTION:Steel parts used in an atmosphere causing severe corrosion at high temp. such as a boiler tube are put in a cementation zone B, and vapor of an Ni halide such as NiCl2 and vapor of a Cr halide such as CrCl2 generated from a heating evaporator 1 in a starting material heating zone A are introduced into the zone B together with a carrier gas such as gaseous Ar. NiCl2 and CrCl2 are reduced to deposit Ni and Cr on the surface of each of the steel parts, and they are diffused into the surface to form an Ni-and Cr- enriched layer having >=5mum thickness. The unreacted NiCl2 are recovered in a starting material recovering zone C together with the gaseous Ar. The resulting steel parts have superior corrosion resistance in a corrosive atmosphere at high temp. |
