Study of molten salt corrosion of HK-40m alloy applying linear polarization resistance and conventional weight loss techniques

Corrosion rates from electro-chemical polarization resistance technique (LPR) and weight loss method (WL) of HK-40m alloy exposed to 80 mol% V₂O₅-20Na₂SO₄ at 600 and 700 °C were obtained at a maximum time of 10 days. Results were supported by X-ray diffraction and electron microscopy analysis. A comparison of corrosion rates from both techniques indicated that corrosion rates from LPR were higher than that from WL, being the values more or less in the same order of magnitude. At 600 °C corrosion rates values were twofold; whereas at 700 °C threefold. The difference in results from both techniques was mainly explained by the fact that V₂O₅ behaves as a semiconductor oxide, and even though Na₂SO₄ is totally ionic, the corrosion mechanism with this mixture may not display a purely electro-chemical process. Some qualitative characteristics were observed for both techniques.