Enhancement of Molten Salt Corrosion Resistance of Ni-Based Superalloy Through Adding Inhibitor

Abstract

Recently, molten salt corrosion of metallic alloys in concentrated solar power (CSP) industries is one of the important and unavoidable issues among others. In this investigation, the role of inhibitor (i.e., Mg powder) on the hot corrosion behavior of Inconel 617 superalloy in molten chloride salts mixture has been examined through immersion corrosion test method and electron microscopic analysis. Post-corrosion observations revealed that Cr at the grain boundary is preferentially depleted, which leads to severe grain boundary corrosion. By addition of 1 wt% Mg powder (as inhibitor), the corrosion rate (derived through percolation depth) was observed to be remarkably minimized by similar to 40% compared with the immersion test without Mg powder addition. The notable increase in corrosion resistance by the addition of Mg powder could be attributed to the reduction of oxidizing impurities in the molten salts mixture, which is considered to be the main culprit for the corrosion promoter.