| "Energy saving, green, environment protecting"is the developing trend in nowdays. As "Green Engineering Materials in 21st Century", magnesium alloy is the favor of industry for its unique excellent properties (low density, specific strength and stiffness, etc.). But the poor performance in corrosion resistance, hardness, wear resistance,magnesium alloy is limited to applied to industry widely to some extent. In order to expend and explore the magnesium alloy's potential, we have to adopt some technology to improve its corrosion resistance and wear resistance, which is important to the application of magnesium alloy.In this paper, in order to improve the property of anticorrosion and wear resistance, AZ31B magnesium alloy is treated with laser cladding technology by 5kW transverse flow CO2 gas laser. The Al-Si coating and Al-Si+Al2O3/TiO2 composite coating is studied by OM,SEM,EDS,microhardness tesster,friction and wear tester,electromical tester from the following aspects: microstructure, phase, micro hardness, wear properties and electrochemical corrosion resistance.Obtained well metallurgical bonding and interface is clear after laser cladding treatment with low melting point Al-Si powder on AZ31B magnesium alloy. Compared with the original magnesium alloy, grains becomed much more refined. Coating mainly consists of Mg,Mg17Al12,Mg3Al2,Mg2Si,Al2Mg composition. The value of hardness lifted from 50HV0.05 to 150HV0.05, 3 times than substrate. Wear resistance is studied from morphology, friction coefficient and wear loss. Wear scar width is 780μm, 35.0% lower than the substrate; the friction coefficient tends to invariant, average value of friction coefficient is 0.26, 0.34 lower than that of matrix; The wear loss is about 2.0×10-3g, lower 42.8% than that of original magnesium alloy; The result of electrochemical corrsion show that the corrosion potential of AZ31B magnesium alloy is -1.14V, 0.37V higher than that of matrix, and the corrosion current is 0.0358A/cm2, 0.0827A/cm2 lower than that of matrix, corrosion mass is 0.0216g, 47.0% higher than that of matrix.In order to obtain better performance, the Al-Si powder and Al2O3/TiO2 ceramic powder were mixtured with different mass ration, which were 4:1,6:1,10:1 respectively. The cladding is composed of gray matrix,black dendrite,white particle. Phase analysis showed that three types of coating were composed of Mg17Al12,Al3Mg2,Mg2Si,Al2O3,TiO2 five compounds. The peak of Al2O3,TiO2 were high when the propotion is 6:1, which indicated that there were much ceramic phase in the cladding.Hardness testing showed that three rations have improved. The maximum hardness is about 225 HV0.05, icreased 3.5 times than the substrate, and raised 50.0% than Al-Si coating. Wear track width of three ratios coatings were 430μm,400μm,450μm,much smaller than the original magnesium alloy. Friction coefficient is 0.25,0.25,0.27 respectively, 0.35,0.35,0.33 less than that of matrix. The wear loss is 0.8×10-3g,0.6×10-3g,1.0×10-3g, which decreased 77.1%,82.8%,71.4% than the original magnesium alloy. Corrosion potential of three ration coatings were -1.19V,-1.16V,-1.06V, improved 0.32V,0.35V,0.45V than base metal, while the corrosion current decreased an order of magnitude. Corrosion mass is 0.0190g,0.0178g,0.0256g, which decreased 53.6%,56.5%,37.5% than the original magnesium alloy.
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