Structural features and corrosion analysis of thermally oxidized titanium

Thermal oxidation process tends to improve surface characteristics of titanium alloys by thickening the native oxide film. In the present paper, the influence of short cycle thermal oxidation on corrosion behaviour of Ti-6Al-4V alloy is reported and the improvements are discussed in terms of process parameters. Oxidation treatments were carried out in the range 500-800 degrees C for 1-h cycles in muffle furnace under air atmosphere. Characterization of modified surface layers was made by X-ray diffraction, glow discharge optical spectroscopy and scanning electron microscopy. Evaluation of corrosion properties of the specimens by potentiodynamic polarization tests indicated that surface treated titanium had better corrosion resistance than untreated material. From the comparison of experimental findings, it is concluded that 600 degrees C is the appropriate oxidation temperature for improvement of corrosion resistance of the titanium alloy. This is different from the conditions suggested by previous researchers who optimized the process for wear resistance. (C) 2009 Elsevier B.V. All rights reserved.