Microstructure and corrosion behavior of electroless deposited Ni-P/CeO2 coating

Electroless Ni-P/nano-CeOcomposite coating was prepared in acidic condition,and its microstructure and corrosive property were compared with its CeO-free counterpart.Scanning electronic microscopy (SEM) and X-ray diffraction (XRD) spectrometer were used to examine surface morphology and structure of the as-plated coating.Differential scanning calorimeter (DSC) and transmission electronic microscopy (TEM) were used to study the coating’s phase change at high temperature.The coating’s corrosive behavior in 3%NaCl+5%HSOsolution was also investigated.The results showed that Ni-P coating had partial amorphous structure mixed with nano-crystals,while the Ni-P/CeOcoating had perfect amorphous structure.In high-temperature condition,NiP precipitation and Ni crystallization took place in both coatings but at different temperatures,while the Ni-P/CeOcoating had sintered phase of NiCeOspinels.The anti-corrosion property was better in the CeO-containing coating,and this was due to its less liability to undergo local-cell corrosion than its CeO-free counterpart.Ni-P/CeOcoating’s pure amorphous structure was the result of Ni’s hindered crystal-typed deposition and P’s promoted deposition.