Fabrication and properties of Al2O3-TiB2-TiC/Al metal matrix composite coatings by atmospheric plasma spraying of SHS powders

The Al2O3-TiB2-TiC/Al metal matrix composite coatings were deposited onto MB26 magnesium alloy substrates by atmospheric plasma spraying (APS) using the powders produced by self-propagation high-temperature synthesis (SHS). Phase composition and microstructure of the SHS powders and APS coatings were characterized by XRD and SEM. Microhardness, bond strength and wear resistance of the composite coatings were investigated by using a Vickers hardness tester, pull-off tester and pin-on-desk tribometer. The APS composite coatings mainly consisted of TiB2, TiC, excess Al and two types of alumina. The coatings bonded well to the substrate. Microhardness and wear resistance of the coatings increased significantly in comparison with that of the MB26 substrate. The applied load and the fraction of Al content were found to be the most effective factors on the wear rate of the coatings.