Patent ID: 9702838
Date: 2017-07-11
CPC Classifications: C22C,C22F,F02P,G01N,H01T

Claim:
1. A method comprising: a wet etching step of preparing, as a metal material, a sample composed of a nickel-based metal, preparing, as a corrosive solution, an aqueous solution containing an acid and sodium chloride, and immersing the sample in the corrosive solution to form a Ni-enriched phase in a surface layer region of the sample; a combustion step of exposing the sample that has been immersed in the corrosive solution to a flame of engine oil so that the Ni-enriched phase is brought into contact with a component in the engine oil to form a low-melting point phase in the surface layer region of the sample; and a heating step of heating the sample that has been exposed to the flame of the engine oil to melt the low-melting point phase and resolidifying the low-melting point phase.