Unveiling the contribution of lactic acid to the passivation behavior of Ti–6Al–4V fabricated by laser powder bed fusion in hank’s solution
Acta Metallurgica Sinica (English Letters)
School of Engineering / Centre for Advanced Materials and Manufacturing
Fundamental Research Program of Jiangsu Province / Australian Research Council through the Discovery Project / Basic and Applied Basic Research Foundation of Guangdong Province, China / Foshan (Southern China) Institute for New Materials
In actual physiological environments, bacteria can activate the immune system and release lactic acid. However, the detailed contribution of lactic acid to the passivation behavior of titanium (Ti) alloys is still unclear. The current work investigated the in vitro passivation behavior of Ti–6Al–4V (TC4) alloys fabricated by laser powder bed fusion in Hank's solution with and without adding lactic acid. Electrochemical methods, inductively coupled plasma atomic emission spectrometer, and X-ray photoelectron spectroscopy were jointly used. Adding lactic acid decreases the corrosion resistance of samples by degrading the formed passive film. The film formed in the (lactic acid)-containing solution exhibits a higher level of oxygen vacancies and a lower thickness, attributed to the suppressed formation of Ti4+ transformed from Ti3+ and Ti2+. Moreover, the presence of lactic acid would increase the open circuit potential, relieve the ions release, and hinder the deposition of calcium phosphates within 24 h immersion. © 2023, The Chinese Society for Metals (CSM) and Springer-Verlag GmbH Germany, part of Springer Nature.