Microstructure and wear behaviour of laser-induced thermite reaction Al₂O₃ ceramic coating on AA7075 aluminum alloy

The microstructure and wear behaviour of the thermite reaction coating produced by the hybrid laser cladding-remelting on AA7075 aluminum alloy for the systems of Al-CuO-SiO₂, Al-Cr₂O₃-SiO₂, Al-Fe₂O₃-SiO₂, and Al-TiO₂-SiO₂ were studied. The results of the X-ray diffraction (XRD) analysis show that in all the four reaction coatings, α-AI₂O₃ and γ-Al₂O₃ phases were present at the top surface, together with various intermetallic phases, the corresponding reduced metal and Al phase in the fusion zone. Under the dry sliding condition, the wear resistance, in terms of weight loss, of the laser-clad specimens was considerably higher than that of the untreated specimen. The predominant wear mechanism of the former specimens was abrasive wear, while for the latter, it was the adhesive wear that prevailed.