Effect of silicon on corrosion resistance of Ti–Si alloys

The corrosion resistance of Ti–Si alloys has been studied in acid solutions and the alloys exhibit a high resistance to corrosion. SEM examinations combined with EDAX allowed to conclude that the passive films on Ti–Si alloys are mainly composed of TiO2/SiO2 oxides. XPS analysis indicated the formation of Si–O and Si–O–Ti bonds in the passive film, respectively corresponding to SiO2 and Si-doping TiO2. The effect of silicon on the corrosion was correlated to the formation of a stable SiO2 film, Si-doping on TiO2 and the extended lattice imperfections formed along TiO2/SiO2 grain boundaries and phase-boundaries. The calculated donor densities based on the point defect model were shown to depend exponentially on pH and linearly on potential.