Corrosion study of Ni-based alloy in ternary chloride salt for thermal storage application

Abstract

MgCl2/NaCl/KCl salt appeared as a high-potential heat transfer fluid for concentrated solar application, offering a wide operating range and low cost. Nevertheless, MgCl2 hydrates and atmosphere relative humidity are the limiting factors for a real scale CSP plant, leading to severe corrosion. Thus, Inconel 617 was tested at 700ºC up to 24 h in air atmosphere to simulate a punctual failure in the inertization system of a plant. XRD and SEM-EDX analysis showed unstable multilayers growing in cascade, highlighting chromium, aluminum, magnesium, and oxygen activities. Additionally, A radial growth of MgCr2O4 at the expense of MgO grains was visualized.