Hot corrosion of Ni, Cr, and 80Ni20Cr in the presence of NaCl and water vapor at 750 °C

The hot corrosion of Ni, Cr, and 80Ni20Cr in the presence of NaCl and water vapor at 750 °C was studied. The results indicated that no significant oxidation or corrosion effect of Ni was found in this case. However, a severe damage caused by the synergistic effect of NaCl deposit and water vapor on Cr was found. Both theoretical and experimental results have shown that Cr could react with NaCl or water vapor and form corrosive Cl2 or HCl, accelerating the corrosion of Cr by chlorination and oxidation. The element Ni in 80Ni20Cr alloy was accelerated corroded by means of reactions among Cr and solid NaCl as well as water vapor. Pure Cr and 80Ni20Cr are corroded by synergistic effect of NaCl deposit and water vapor at 750 °C which is below the melting point of NaCl. Cr could react with NaCl or water vapor accelerating the corrosion of Cr by chlorination and oxidation. The corrosion of Ni is not accelerated in the presence of water vapor or NaCl. However, the element Ni in 80Ni20Cr alloy is accelerated corroded when exposed to the atmosphere of HCl or Cl2.