AFM Analysis and Corrosion Resistance Study on High Phosphorus Ni-P Coating

Corrosion resistance of electroless plating Ni-P binary alloy was closely related to its microstructure and surface morphology. High phosphorus coating with 11.54%P was obtained by experiment, which belonged to amorphous structure. Crystallization process of the microstructure started at 300 degrees C, and completed at 400 degrees C, thereafter nickel matrix phase transformed to Ni(3)P+Ni mixed stable phase. An Atomic Force Microscope was used to study the surface morphology of Ni-P coating before and after different heat treatments. It was found that the corrosion resistance was affected by the surface morphology of heated coatings. The corrosion resistance was best after 400 degrees C heat treatment because the "nano-plant" covered the coating surface.