Corrosion of carbon steel and cast iron in gas phase above salt melts used in magnesium industry

Abstract

Corrosion tests of SCh15 cast iron, Steel 3 and Steel 3 with aluminized coating in some compositions of 10%MgCl2-KCl-NaCl and 10%MgCl2-KCl-Naa-Caa2 salt melts with 10 %, 25 % and 40 % CaCl2 concentrations, and also in 10MgCl2-45%KCl-20%NaCl-25%NaBr melt, and in the gas phase above these melts at 700 °C. A gravimetric method was used to determine corrosion rates of metal samples. Chemical analysis of absorption solutions was used to determine concentrations of halide and hydrogen halide impurities in air blown through the reactor with melts and samples. It was shown that carbon steel aluminizing can reduce the corrosion rate in the gas phase over the salt melt by a factor of 5 to 70. The formation mechanism of gases aggressive in relation to carbon steel and cast iron in atmospheric air in contact with salt chloride melt was considered. Accelerated hydrogen chloride and chlorine formation during the salt melt interaction with atmospheric air under the influence of iron corrosion products was found.