Corrosive effects of nitrate-containing phase change materials used with copper

The paper presents the results of a study on the corrosion behaviour of copper (EN CW004A) in five possible phase change materials (PCMs): magnesium nitrate hexahydrate pure and with an addition of Mg(OH)₂ (0.5 wt. %) or Sr(OH)₂ (0.5 wt. %) at 90 °C, calcium nitrate tetrahydrate at 50 °C and a mixture of magnesium nitrate hexahydrate and calcium nitrate tetrahydrate (1:1 mass ratio) at 72 °C. The corrosion rate of copper samples is low except for the use of Mg(NO₃)₂ · 6H₂O with/without an addition of Mg(OH)₂. The lowest corrosion rate was observed for the mixture Mg(NO₃)₂ · 6H₂O—Ca(NO₃)₂ · 4H₂O (1:1), and it was ca six times lower than that of pure magnesium nitrate hexahydrate.