Effect of water vapor content on corrosion performance of aluminide coatings on TP347H in a simulated biomass combustion environment

Large numbers of power plants are taking biomass energy to replace fossil fuels. However, biomass combustion process deposits a substantial amount of potassium chloride in the boiler pipe, which causes high-temperature corrosion. This paper investigated the corrosion mechanism of aluminide coatings deposited on TP347H stainless steel under experimental conditions with different water vapor content in a simulated biomass combustion environment. H2O promoted the production of more dense multilayer metal oxides in the aluminide coating on the TP347H stainless steel in the presence of water vapor. The coatings suffered the most severe intergranular attack without water vapor. The intergranular corrosion of coatings subjected to 30% water vapor was less severe than that of coatings exposed to 15% water vapor due to the corrosion inhibiting impact of water vapor. It is indicated that water vapor can essentially influence the corrosion process in a biomass combustion environment.