Revisit the Type II Corrosion Mechanism

Abstract

Since it was first proposed in the early 1980s, Type II hot corrosion has been widely cited in the literature as a process of molten sulfate attack on high-temperature alloy components. In the current study, typical Type II corrosion pits observed on field components were characterized using high-resolution TEM technique. The corrosion products in the pits were found to be mainly of nanosized sulfides and oxides, but not of the hypothesized sulfates. The results suggest a solid-phase corrosion process involving the cooperative precipitation of fine sulfides and oxides at the corrosion front.