High-Temperature Corrosion of Fe-Cr Alloys in Water and HCl Vapor Environments at 500–600 °C

Understanding the corrosion mechanism inside waste incinerators is very important in order to prevent possible damage due to high operational temperatures in chemical reactions for burning raw hazardous materials. Moreover, it is critical to understand the corrosion mechanisms to identify whether the oxides formed are protective or not, enabling us to prevent mass change on the steel walls of heat exchangers in waste incinerators. Thus, the present work comprises a high-temperature corrosion study on four Ferritic alloys with different contents of Al, Si, and Mo which are capable of replacing expensive materials such as stainless steel. The corrosion behavior was evaluated in atmospheres with H2O(g), HCl(g), and an additional mixture of both atmospheres at 500 and 600 °C over 300 h. A thicker but porous heterogeneous oxide scale was formed in the HCl atmosphere, mainly composed of Fe2O3 and Cr2O3. Under the water vapor atmosphere, the presence of (Fe0.6Cr0.4)2O3 was observed. Meanwhile, in the mixed atmosphere, the presence of FeCr2O4, Cr2SiO4, and (CrFe)2O3 was observed. The biggest mass loss was measured inside the water vapor atmosphere. In comparison, inside the mixed atmosphere, the oxide scale was thinner. Finally, it was concluded that the alloy with the best corrosion resistance in HCl and H2O atmospheres was Fe9Cr1.5AlSi3Mo steel.