Robust corrosion performance of cold sprayed aluminide coating in ternary molten carbonate salt for concentrated solar power plants

Abstract

In concentrated solar power (CSP) technology, high temperature corrosion is a key issue for material selection. In this context, a homogeneous and crack-free FeAl coating with high Al content was prepared by using cold spray (combined with a post heat treatment) to improve the corrosion resistance of stainless steel 316 L (SS316L) in molten carbonate salt for CSP applications. A series of immersion corrosion tests were performed to explore the corrosion behavior of the prepared aluminide coating in the LiNaK molten carbonate salt at 700 °C. The results demonstrated that the corrosion resistance of SS316L in the molten carbonate salt can be greatly improved by the prepared aluminide coating. This is attributed to the formation of a continuous dense LiAlO2 layer on the surface of the coating during corrosion. Although an α-LiAlO2 → γ-LiAlO2 phase transformation occurred during corrosion, it showed little influence on the corrosion performance of the prepared coating under the present experimental conditions. Furthermore, the coating remained intact even after 1000 h of corrosion. It is envisaged that the prepared coating has broad application prospects for CSP system with molten carbonate salt medium.