High-temperature corrosion resistance of Fe–Cr–Mo amorphous coating for water wall protection of USC boiler

Abstract

A novel Fe–Cr–Mo amorphous coating, a high-temperature corrosion-resistant material for water wall protection of power plant ultra-supercritical boilers, has been prepared via arc spraying. A systematic study was conducted to evaluate the high-temperature corrosion behavior of this coating, and its resistance to corrosion at high temperatures was scientifically assessed. The results indicate that the thickness of Fe–Cr–Mo amorphous coating is approximately 350 μm, exhibiting typical amorphous characteristics as confirmed by X-ray diffraction and transmission electron microscope characterization. During each stage of the 750 °C corrosion test, the oxygen content of the amorphous coating was significantly lower than that of the contrast coating (PS45 alloy coating), indicating a superior corrosion protection effect at high temperature. After 100 h of continuous testing, the corrosion mass gain of the amorphous coating was only 28.62% that of PS45 coating and 3.89% that of T12 steel substrate, indicating significantly depressed high-temperature corrosion kinetics. The excellent high-temperature corrosion resistance of Fe–Cr–Mo amorphous coating is primarily attributed to the stable Fe/Cr oxide film generated by the metastable state of the amorphous state, which serves as an excellent barrier. Furthermore, under the influence of heat in a high-temperature environment, the amorphous structure gradually transforms into a nanocrystalline structure. In contrast, the oxide film of the amorphous/nanocrystalline coating has low thermal stress, leading to better adhesion with the coating and resistance to cracking and peeling, thus providing excellent sustained protection.