The deterioration effects of corrosion product deposition on Ni-Cu alloy in hydrofluoric acid vapor phase

Abstract

The corrosion behavior of Monel 400 alloy in HF vapor and liquid phases are compared in this study. More severe corrosion is observed in the vapor phase, which is attributed to the discrepancy in corrosion product layer. Specifically, a loose and porous fluoride layer is observed in the vapor phase, whereas a compact oxide layer is formed in the liquid phase. According to thermodynamic analysis, the formation of fluoride layer can be caused by higher O2 content, HF concentration, or corrosion product deposition in the vapor phase. And, the corrosion product deposition is found to play the dominant role.