Effect of laser irradiation on high-temperature crystallization behavior, oxidation resistance, and corrosion performance evaluation of electrodeposited amorphous Ni-P coatings

Amorphous Ni-P alloys crystallize at high temperatures, which leads to the deterioration of resistivity and corrosion resistance. In this study, the use of laser irradiation with the electrodeposition (ECD) process for preparing amorphous Ni-P coatings was investigated; and the resistivity and corrosion resistance were analyzed, which is related to crystallization process, surface morphology, residual internal stress, and oxidation layer. The results indicates that the crystallization rate of Ni-P coating prepared by laser-assisted electrodeposition (LECD) was slower than that of ECD coating. With increasing ambient temperature, the internal tensile stress first decreased and then increased. The LECD coating has better oxidation resistance, with XPS indicating the oxide layer mainly comprised Ni-O compounds. At the same ambient temperature, the resistivity of the LECD coating was higher than that of the ECD coating. The Ni-P coating had better corrosion resistance after heating, and the corrosion mechanism changes from stress corrosion to pitting corrosion.