Screening of materials in NaCl-MgCl2 at 600 °C– a comparative study leading to a new corrosion-resistance criterion

The behavior of several materials in molten NaCl-MgCl ₂ at 600°C during 168 h was studied. In order to ensure the comparison of their respective corrosion resistance, a dedicated experimental set up and protocol were designed both for the control of the impurity level in the salt and for the corrosion testing. IN625 was used as a reference sample in every test, leading to a qualitative comparison between the different alloys. In these conditions, the SiC showed the best resistance while TA6V and 316L suffered the most. For Ni-based alloys, Hastelloy G35 seemed to provide the best compromise despite its high chromium content. Thermodynamic calculations unveiled a strong link between the corrosion resistance of the alloy and a high dµCr/dnr leading to consider this as a new criterion for alloy design or selection.