Lijuan Hao

Corrosion behaviour of electroless Ni–P coatings in simulated acid rain

Abstract The corrosion behaviour of electroless Ni–P coatings deposited on A3 steel in simulated acid rain at pH=3·5, 4·0, 4·5, 5·0, 5·5 and 6·0 were investigated by weight loss test and electrochemical test. The protection of A3 steel by Ni–P coating was discussed, and 1Cr18Ni9Ti austenitic stainless steel was used for comparison. The results indicate that the weight loss of the three materials increased, and the corrosion resistance of Ni–P coating decreased, with decreasing pH value of the acid rain solution. The corrosion resistance of A3 steel can be significantly improved with the protection of Ni–P coating, which showed better corrosion resistance than 1Cr18Ni9Ti stainless steel.

Corrosion characteristics of electroless Ni-P coatings deposited on W-Cu composite

Abstract Electroless Ni–P coatings were deposited on W–Cu composite substrates using an anodic activation and strike nickel plating pre-treatments; they were then subjected to heat treatment. The morphology and structure of Ni–P coatings were examined using SEM and XRD, also the corrosion characteristics of Ni–P coatings in 3·5 wt-% NaCl solution were investigated by electrochemical tests. Results indicated that the heat treatment temperature affected the surface morphology, structure and corrosion resistance of Ni–P coatings. The weight loss results indicated that the Ni–P coating had a smaller corrosion rate than W–Cu composite in 3·5 wt-% NaCl solution.