Characterization of Ni-P/TiO_2 MMC coatings prepared by electroless plating process on Mg-Nd-Zn-Zr magnesium alloys

摘要

Ni-P/TiO_2 metal matrix composite (MMC) coatings were prepared by electroless plating process combined with sol-gel technology on Mg-3.0Nd-2.0Zn-0.4Zr (wt.%, NZ30K) magnesium alloys. The reinforcement of TiO_2 nanoparticles was added into the solution of electroless plating in the form of transparent alcoholic sol. The microstructures and compositions of the prepared Ni-P/TiO_2 MMC coatings were investigated by Field Emission Scanning Electron Microscopy (FE-SEM). The phase composition of the coating was analyzed by X-ray diffraction (XRD) facilities. It was found that the TiO_2 nanoparticles were highly dispersed in the coating matrix. The microhardness of Ni-P/TiO_2 MMC coating was far higher than those of NZ30K substrate and Ni-P coating due to the incorporation of in-situ formed TiO_2 nanoparticles. Electrochemical measurements indicated that the corrosion resistance of Ni-P/TiO_2 MMC coatings was superior to NZ30K substrate but no obvious significant change could be seen compared to Ni-P coating.