The Effect of Water on Passivity and Pitting of Titanium in Solutions of Methanol and Hydrogen Chloride

Abstract

The effect of water on passivity and breakdown of passivity by pitting of titanium in solutions of methanol and hydrogen chloride has been studied. In anhydrous solutions no passivation occurs. Small additions of water lead to passivation, the region of passivity being limited by the pitting potential to noble values. The critical pitting potential becomes more noble with increasing water content of the electrolyte. Values obtained under steady‐state conditions seem to level off at higher water contents, while values obtained under nonstationary conditions increase linearly with water content. No passivation occurs when 12N aqueous was added to pure methanol to produce an aqueous solution of , but passivation was observed when an aqueous solution of was produced. This is explained by the higher water content of the latter solution, which is sufficient to passivate the surface at potentials below the pitting potential.