Erosion resistance of laser textured plasma-sprayed Al2o3-13%Tio2 coatings on mild steel

Abstract

A micro-grooved texture was fabricated on the surface of a plasma sprayed alumina-13% titania (Al2O3-13%TiO2) coating using laser surface texturing (LST) method. Aspects of hardness, phase composition and erosion wear resistance of the textured coating were investigated and compared with those of non-textured coating. As for the erosion study, a standard slurry pot erosion test was conducted in silica (SiO2) slurry at different impact angles of the SiO2 particles. Microstructural features of both textured and non-textured coatings were characterised with Scanning Electron Microscopy (SEM) analysis to evaluate the failure of coatings due to wear behaviour. The results revealed that the LST technique is indeed an effective way to alter the surface characteristics of plasma-sprayed Al2O3-13%TiO2 coating with minimal effect on mechanical properties and phase composition of the coating. The SEM analysis displayed formations of erosion scar and crack propagation on the coating surface. Based on the impact angle effect, the cumulative mass loss of the coating was greater at 90° when compared to 30°. In this study, the cumulative mass loss of the textured coating decreased up to 45% at the impact angle of 90° with 750 rpm slurry velocity; signifying enhanced coating resistance against erosion by engraving micro-grooved texture onto its surface.