In order to improve the wear and corrosion resistances of magnesium alloys and broaden their application areas,a layer of Al-20％(mass fraction) Al2O3(abbreviated as Al-Al2O3) coating was firstly deposited on the surface of the magnesium alloy substrate by cold spraying method as the transition layer of the composite coating,and then an Al2O3-13％(mass fraction) TiO2(abbreviated as AT13) surface layer was prepared on its surface by atmospheric plasma spraying method,thereby obtaining an Al-Al2O3/AT13 composite coating. Subsequently,the surface and cross-sectional morphology of the transition layer and surface layer were analyzed by scanning electron microscopy,and the micro-hardness and bonding strength of the composite coating were measured using a microhardness tester and a universal testing machine. Moreover,the friction coefficient and wear rate of the composite coating were measured by a friction and wear tester,and the corrosion behavior of the composite coating in a 3.5％(mass fraction) NaCl solution was investigated through dynamic potential scanning technology. Results showed that the microhardness of the Al-Al2O3 transition layer and the AT13 surface layer were (42.3±13.7) HV0.1 and (838.8±87.6) HV0.1,respective-ly,and the bonding strength of the Al-Al2O3/AT13 composite coating was 31.2 MPa. Additionally,the stable friction coefficient and wear rate of the composite coating were 0.74 and 5.94×10-5 mm3/(N·m) under a load of 40 N and a wear condition of 10 min,and compared with the magnesium alloy substrate[1.89×10-4 mm3/(N·m)],the wear rate was reduced by 68.6％. After being immersed in a 3.5％NaCl solution for 30 min,the corrosion potential of the composite coating was-927 mV,and the corrosion current density was 1.81×10-5 A/cm2. Compared to the magnesium alloy substrate,the corrosion potential increased by 742 mV,and the corrosion current density decreased by an order of magnitude.
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