Evaluation of Micro Hardness of Magnesium Alloy Coated with ZnO and Al2O3

Magnesium and its alloys have wide range of application in automobile and aircraft industries because of their excellent mechanical properties i.e. high strength to weight ratio, availability and good castability etc. However, some challenges occur in using magnesium in aquas service applications, due to its highly reactive nature and low tribological properties such as low wear and corrosion resistance. In this work an experimental study has been done on uncoated and ceramic coated AZ91 alloy to compare hardness and wear properties of both. The coating was applied on varying weight percentage of ZnO and Al2O3 ceramic particles. The effect of presence of ceramic particles on the surface of substrate was studied using scanning electron microscope. Micro Vickers hardness test and wear tests were conducted on the samples, and it was found that coating of ceramic particles made the surface harder and wear resistant as compared to the uncoated Mg alloy. Contribution of Al2O3 particles plays an important role in increasing the hardness and wear resistance of coated surface. A decrease of 84% in coefficient of friction, increase in wear resistance by 99% and increase in micro hardness by 92% was reported for Al2O3 coated sample as compared to the uncoated surface.