This work investigates the characteristics of oxide films formed on Ti and the Ti alloy through a plasma electrolyte oxidation (PEO) process in highly alkaline medium in the presence or absence of phosphate ions. The obtained coatings showed different characteristics when they formed in high alkaline phosphate solutions particularly was anatase for Ti and rutile/titanium phosphate for the Ti alloy layer. Films formed in aqueous solution without KOH caused a reduction in current density and also reduced the number of microarcs, while in electrolytes with high OH- concentration, the current was low and the density of sparks was significant.

Plasma electrolyte oxidation (PEO) was utilized to produce thick films on titanium and Ti-5Mo-4V-3Al alloys by immersing them in various solutions of Na 2 SiO 3 and KOH with different concentrations to investigate the effect of SiO 2 3 -/OH -relations on the morphology and formed phases by utilizing SEM and XRD. Corrosion resistance is evaluated by open circuit potential (OCP) variation of samples in NaCl 3⋅5% and potentiodynamic polarization. The results show that the unstable film is formed by using more aggressive PEO electrolyte. By increasing this ratio, pore size varied from fine to coarse and the rate of corrosion decreased and OCP became more positive. The best protective film was formed in SiO 2 3 -/OH -ratio of 1.