Impedance Spectroscopy Applied to Metal Corrosion Study in Silicate Melts

Abstract

The determination of the corrosion processes of metallic materials in glass melts is of great interest for glass makers. Our attention has been specifically focussed on Cr-bearing alloys that form Cr2O3 layers when they are immersed in a silicate melt and offer a good resistance to melt corrosion. The comprehension of the corrosion processes has been extensively studied in the last 10 years using stationary electrochemical techniques. Results relative to the thermodynamic state were described. Complex impedance spectroscopy offers the possibility to determine the reaction kinetics in terms of limiting processes. Three chromium rods were directly immersed in molten glass at T=1050°C, maintained respectively in the active, passive and transpassive state and studied using electrochemical techniques. The results that are reported in this paper show a good agreement between complex impedance spectroscopy data, scanning electron microphotographies of the glass/metal interface and previous results obtained using stationary electrochemical techniques.