Effect of Thermal Oxidation on Corrosion Resistance of Commercially Pure Titanium in Acid Medium

Abstract

This article addresses the characteristics of commercially pure titanium (CP-Ti) subjected to thermal oxidation in air at 650 A degrees C for 48 h and its corrosion behavior in 0.1 and 4 M HCl and HNO3 mediums. Thermal oxidation of CP-Ti leads to the formation of thick oxide scales (similar to 20 mu m) throughout its surface without any spallation. The oxide layer consists of rutile- and oxygen-diffused titanium as predominant phases with a hardness of 679 +/- A 43 HV1.96. Electrochemical studies reveal that the thermally oxidized CP-Ti offers a better corrosion resistance than its untreated counterpart in both HCl and HNO3 mediums. The uniform surface coverage and compactness of the oxide layer provide an effective barrier toward corrosion of CP-Ti. The study concludes that thermal oxidation is an effective approach to engineer the surface of CP-Ti so as to increase its corrosion resistance in HCl and HNO3 mediums.