Chemical and Electrochemical Behaviour of Titanium in Methanol-Water-HCl Mixtures

Abstract

The passivity of Ti has been investigated in methanolic solutions of hydrochloric acid, containing various amounts of water using a potentiostatic method. A stable oxide film can be formed on the metal surface only in solutions with a molar ratio of water to protons greater than 4:1. At lower molar ratios, a thick black non-protective layer covers the surface of the titanium electrode during anodic polarisation. Open circuit potentials of Ti were measured in strongly aerated solutions of methanolic 1M HCl, aqueous 1M HCl and aqueous 1M HCl containing 0·001M of KClO₃, KBrO₃, or KIO₃. It was found that the potential of a Ti electrode is unstable in methanolic 1M HCl solution. The rate of film thickening on Ti in aqueous solution was measured in relation to the type of the oxidising agents used.

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