Titanium corrosion in molten glasses : Part 2. Electrochemical study and corrosion mechanismus

Abstract

In situ electrochemical experiments are carried out to determine the mechanisms of pure titanium corrosion in molten glasses. The corrosion layers formed at the metal/glass interface are systematically reported. The formal potentials of the TiIII/TiII and TiIV/TiIII redox couples are respectively positioned at -1.0 V and -0.7 V by coupling square wave voltammetry measurements and polarization of titanium rods. The potential of the BIII/B0 couple is estimated to be near -1.4 V. The results obtained by immersion tests and electrochemical measurements in glasses are compared. They are consistent in terms of corrosion rate variations and morphology of the corrosion scales. The corrosion mechanisms are described in the form of successive redox reactions between the glass and the substrate followed by diffusion of the formed species into the titanium substrate. It is demonstrated that Ti does not form spontaneously protective scales when immersed in molten glass and that protection can not be reached by either anodic or cathodic polarization.