Effect of laser remelting on microstructure and wear resistance of plasma sprayed Al2O3-40%TiO2 coating

Abstract

The Al2O3-40%TiO2 coating fabricated by plasma spraying on carbon steel substrate were remelted by laser, and the effect of laser remelting on microstructure and wear resistance of plasma sprayed Al2O3-40%TiO2 coating were studied. The microstructure and phase composition of plasma sprayed and laser remelted coatings were analyzed using scanning election microscopy (SEM), energy disperse spectroscopy (EDS) and X-ray diffraction(XRD). The micro-hardness and adhesion strength of two coatings were measured using micro-hardness tester and electronic universal tensile testing machine. The wear resistance of two coatings was tested through a slurry rubber wheel abrasion test machine, and the wear behaviour was also studied by SEM.The results show that metastable phase γ-Al2O3 in coating is completely transformed into stable phase α-Al2O3 after laser remelting. The laser remelted coating becomes much denser, and then its microhardness and adhesion strength have been greatly improved. The laser remelted coating exhibits better wear resistance compared to the plasma-sprayed coating, and the main wear mechanism responsible for wear was microcrack and fracture wear.