The corrosion of carbon steel in nitrate hydrates used as phase change materials

Abstract

Corrosion behaviour of mild carbon steel was studied in five assumed phase change materials: magnesium nitrate hexahydrate, magnesium nitrate hexahydrate with the addition of magnesium hydroxide (0.5 wt%) and strontium hydroxide (0.5 wt%), respectively, at 90 °C; calcium nitrate tetrahydrate at 50 °C and a mixture of magnesium nitrate hexahydrate and calcium nitrate tetrahydrate (1:1) at 72 °C. Corrosion rate was studied via mass loss and the steel specimens were analysed after the study. The corrosion rate of steel specimens is over recommended limit except of the mixture Mg(NO3)2 · 6 H2O − Ca(NO3)2 · 4 H2O (1:1). Steel can be used for the long‐term service in this mixture while in the other cases it can be used only with caution based on the specific application.