Effect of water vapor content on the corrosion mechanism of HR3C in simulated oxy-coal combustion environment

The corrosion performance of the HR3C steels covered with salt deposition (Na2SO4:K2SO4=1:1) was investigated under various water vapor content at 700°C. Results show that the HR3C alloy undergoes severe pitting and sulfidation in a dry corrosive atmosphere (0.5SO2-4O2-CO2) and the corrosion products are peculiarly prone to peel off. In comparison, the corrosion behavior is gradually mitigated with increasing water vapor content. In highly humid corrosive gas (0.5SO2-4O2-20H2O-CO2), the corrosion degree is remarkably faint and the dominant corrosion mode is oxidation. The mechanism responsible for the transition of corrosion mode as water vapor content varied is discussed in detail.