Oxide growth characteristics, kinetics and mechanism of rutile formation on pure titanium

Isothermal oxidation of titanium results in the formation of rutile (TiO2) at temperatures of 600 degrees C - 1200 degrees C. Initial growth of TiO2 occurs linearly with an activation energy of 53 kJ/mol. Subsequent growth happens parabolically with an activation energy of 155 kJ/mol determined through a proposed quantitative oxide growth model. Inert particles were located at air/oxide interface, indicating oxygen ions to be dominant component for growth of TiO2. Crystal structure and defect chemistry of TiO2 suggests that oxygen diffuses through TiO2 via oxygen vacancies primarily. Temperature-dependent isothermal oxidation mechanism of titanium is proposed considering experimental results and thermodynamic arguments.