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Effect of thermal oxidation on the corrosion resistance of Ti6Al4V alloy in hydrochloric and nitric acid medium
Author(s) -
Jamesh M.,
Kumar Satendra,
Narayanan T. S. N. Sankara,
Chu P. K.
Publication year - 2013
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201106321
Subject(s) - corrosion , materials science , rutile , alloy , titanium alloy , oxide , layer (electronics) , metallurgy , thermal oxidation , hydrochloric acid , oxygen , diffusion , chemical engineering , composite material , chemistry , organic chemistry , engineering , physics , thermodynamics
The characteristics of Ti6Al4V alloy subjected to thermal oxidation in air atmosphere at 650 °C for 48 h and its corrosion behavior in 0.1 and 4 M HCl and HNO 3 medium are addressed. When compared to the naturally formed oxide layer (∼4–6 nm), a relatively thicker oxide scale (∼7 µm) is formed throughout the surface of Ti6Al4V alloy after thermal oxidation. XRD pattern disclose the formation of the rutile and oxygen‐diffused titanium as the predominant phases. A significant improvement in the hardness (from 324 ± 8 to 985 ± 40 HV 0.25 ) is observed due to the formation of hard oxide layer on the surface followed by the presence of an oxygen diffusion zone beneath it. Electrochemical studies reveal that the thermally oxidized Ti6Al4V alloy offers a better corrosion resistance than its untreated counterpart in both HCl and HNO 3 medium. The uniform surface coverage, compactness and thickness of the oxide layer provide an effective barrier towards corrosion of the Ti6Al4V alloy. The study concludes that thermal oxidation is an effective approach to engineer the surface of Ti6Al4V alloy to increase its corrosion resistance in HCl and HNO 3 medium.