Microstructure and properties of Al2O3 and Al2O3-ZrO2 composite coatings on medical NiTi alloy by plasma electrolytic deposition

摘要

AZ91 biomedical magnesium alloy was first treated by Micro arc oxidation (MAO) process and then samples with MAO coating on the surface were subjected by surface laser treating. Effects of laser treating on surface characteristics and corrosion resistance of the coated sample were studied. The results indicated that after surface laser treating, The surface structure of coated sample was improved showing fewer and smaller holes. The AFM photos revealed that the surface roughness of MAO coating was dramatically decreased. The whole surface became more unique and compact. Electrochemical polarization curves tests revealed that the corrosion resistance of MAO coating in SBF was further increased by laser treating, with the corrosion current density decreasing by 10 times and the corrosion potential increasing by 0.06V. Electrochemical impedance spectra (EIS) revealed that the polarization resistance of the MAO coating on AZ91 alloy was also increased by 10 times after surface laser treating.