Heat treatment of AA 6082 T6 aluminum alloy coated with thin Al2O3 layer by fluidized bed

Abstract

Fluidized bed (FB) coating process was used to deposit Al2O3 on aluminum substrates to improve, according to previous studies, the overall mechanical and tribological performance of the underlying Al alloys. Fluidized bed coating allowed achieving a compact and dense layer of Al2O3 fragments, embedded in the outermost layer of the softer aluminum substrates, through an ambient temperature process. In this framework, this work focuses on the effect of a thermal post-treatment of the Al2O3 coating varying the post-treatment temperature and time with the aim of further consolidating the ceramic overlying coating. The high temperature of the thermal post-treatment promoted a diffusion mechanism of the Al2O3 fragments that led to further increments in the mechanical and tribological properties of the aluminum substrates. In this respect, morphology, hardness, corrosion, scratch, and wear resistance of the resulting coatings were investigated. The FB coating process and thermal post-treatment have proven to be suitable for the achievement of a good-looking and well-adhered Al2O3 protective layer, with mechanical and tribological properties that result in highly enhanced aluminum substrates.