Effect of CeO2 particles on the low phosphorus electroless Ni layer

In this paper, the influence of nano-CeO₂ and micro-CeO₂ with different amounts were discussed after they were added into low phosphorus content Ni-P composite coating. The microstructure and crystal structure of the coating were observed by scanning electron microscope (SEM) and X-ray diffraction analysis (XRD) respectively. The results showed that whether nano-CeO₂ or micro-CeO₂, both refined the grain, increased the specific surface area, however the micro-CeO₂ was more obvious. As to XRD, the peak gradually became gentle, the coating turned into amorphous state caused by CeO₂ absorbed in the grain boundary and crystal defects. All the results indicated CeO₂ mixed with the coating very well. Finally, the corrosion resistance of the coating was tested with the method of Electrochemical impedance (EIS) and linear polarization. When the dosage was 5g/L, the corrosion was the best leading by the grain refinement. However, lower corrosion resistance was got when added more CeO₂ which may affected by the catalytic property.