ANODIC CORROSION RATE MEASUREMENTS IN LICL-KCL EUTECTIC .2. RESULTS ON NICKEL, MOLYBDENUM, AND STAINLESS-STEEL

The anodic dissolution characteristics of nickel, molybdenum, and 304 stainless steel have been examined in pure and Li2S-saturated LiCI-KCl eutectic melt. Molybdenum and nickel show Tafel-type dissolution kinetics in pure eutectic which permit estimates of long-term corrosion rates as a function of voltage. Nickel exhibits a sharp threshold potential for dissolution in Li2S-saturated melt, forming a nonpassivating Ni3S2 layer. Comparative volt-ammetry and open-circuit potential measurements with iron in this melt suggest that care may be required in using nickel as an iron sulfide current collector. The anodic dissolution of 304 stainless steel in LiaS-saturated melt appears to be rate limited by diffusion through a reaction layer, showing a (time)-1/2 dependence that may be applicable to long-term corrosion predictions. Dissolution is strongly inhibited by dissolved Li2O, apparently by formation of a protective anodic oxide layer. Molybdenum appears to owe its excellent anodic corrosion resistance in Li2S-saturated melt both to a chemically formed prepassive film and to a well-defined anodic passivation process. However, repetitive cycling to voltages cathodic of 1.5V vs. the lithium electrode may be deleterious. Anodic corrosion of metals should, in general, occur more readily in the Li2S-saturated melt than in pure LiCI-KCI for straightforward thermodynamic reasons. © 1979, The Electrochemical Society, Inc. All rights reserved.