Optimization of ball milling process for fabrication of α-Al2O3 based coatings via laser-assisted combustion synthesis

In this study, the Al2O3 coatings were prepared by using laser-assisted combustion synthesis method with Al-TiO2-C powder mixture. α-Al2O3, a more desired thermally stable phase of Al2O3, has been achieved in a single step without any post-coating treatments. The obtained coating showed a uniform and dense morphology with a thickness of 150 μm and well adhered to the substrate. The absence of porosity and crack in the coating was attributed to the high energy in the fabrication process from both the high power laser and the combustion reaction. The effect of ball milling condition, specifically ball milling time (Tb), on morphology, microstructure evolution and physical properties of the α-Al2O3 based coatings were studied. It was concluded that 2 h ball milling process followed by laser-assisted combustion synthesis is sufficient to prepare an α-Al2O3 based coating with fine structures, which can be expected to be widely used as protective coatings.