The Influence of Heat Treatment Temperature on the Oxidation Resistance of Aluminium Waste Slurry Coating

This research investigated the influence of heat treatment temperatures on the aluminium waste coating produced through the slurry process. The slurry consisted of 57 wt.% of water-based binder solution and 43 wt.% of load agents. The load agent used in this study was aluminium waste powder, which is composed of Al, Fe, Cl, Na, Si, and several other contaminants. The coated samples were heat-treated under Ar (g) flow condition at temperature of 450 °C followed by heating up to 700 °C (HT 700). In contrast, further heat treatment up to 1000 °C (HT 1000) was proposed. The results of heat treatment at 1000 °C (HT 1000) were found to be superior than those of treatment at 700 °C (HT 700). HT 1000 produced a coating with a smooth-like coating structure and a more stable α-Al2O3 phase, resulting in greater resistance to oxidation at a temperature of 800 °C for the 90 h test duration. The study also found that the Cl contaminant has a greater impact on the rate of void formation, resulting in a more compact coating with reduced empty spaces. In contrast, HT 700 samples had notable void development and less stable alumina phases, leading to decreased oxidation resistance.