Microstructure, microhardness and tribological behavior of Al2O3 reinforced A380 aluminum alloy composite coatings prepared by cold spray technique

In the present work, Al2O3 particles reinforced A380 aluminum alloy composite coatings with different Al2O3 content were fabricated by cold spraying (CS). The effect of Al2O3 content on surface roughness, microstructure, microhardness and tribological performance of the composite coatings was studied. Laser confocal imaging, optical microscopy (OM) and scanning electron microscopy (SEM) results revealed that; as the Al2O3 content in the coating increases, the surface roughness decreases while the flattening ratio (FR) of the deformed particles increases due to the tamping effect of the impinging particles. Moreover, Al2O3 particles resulted in increased microhardness and low porosity in the composite coatings due to the refinement of A380 grains and the tamping effect, respectively. The degree of fragmentation of Al2O3 particles increases with the increase of Al2O3 content in the composites. Finally, dry sliding wear tests indicated that the addition of Al2O3 significantly improves the wear properties of the A380 coating as well as the A231 substrate. The improved wear performance of the composites was explained by continuously evolving adhesive, delamination and abrasive wear mechanisms.