Effects of alumina coating on the corrosion behaviors of HT700 alloy in chloride molten salt containing Al corrosion inhibitor

• The corrosion mechanism of the aluminized HT700 alloy in molten salt is revealed. • A large amount of Al powder in molten salt repairs the Al 2 O 3 layer, preventing the diffusion of elements such as Fe and Cr in the alloy. • It has been proven that HT700 alloy with added aluminum infiltration coating has better corrosion resistance. • Research on improving the corrosion resistance of HT700 alloy is of great significance. This study examines the corrosion behavior of HT700 alloy and aluminized HT700 alloy in chloride molten salts with different concentrations of Al powder at a temperature of 700 °C. Aluminide coating enhanced the corrosion resistance of HT700 alloy. The incorporation of aluminum corrosion inhibitors was found to effectively mitigate the corrosion of both HT700 alloy and aluminized HT700 alloy when exposed to chloride molten salts. With the increase of Al content in the chloride molten salt, the corrosion inhibition effect became stronger. A denser and more continuous Al 2 O 3 layer formed on the surface of the aluminized HT700 alloy, providing protective properties to the substrate for a certain period. It impeded the outward diffusion of constituent elements within the alloy, thereby enhancing its resistance to corrosion.