Study on the Deposition of Al-Al2O3/AT13 Composite Coating on the Surface of Magnesium Alloy and Its Wear and Corrosion Resistance Properties
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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