Metallurgical Abstracts on Light Metals and Alloys vol.54
Formation of Carbon-added Anatase-rich TiO2 layers on Titanium and their Antibacterial Properties in Visible Light
Takatoshi Ueda1, Naoki Sato1, Ryusuke Koizumi1, Kyosuke Ueda1, Koyu Ito2, Kouetsu Ogasawara2 and Takayuki Narushima1,3
1Department of Materials Processing, Tohoku University
2Department of Immunobiology, Institute of Development, Aging and Cancer, Tohoku University
3Research Center for Structural Materials, National Institute for Materials Science
[Published in Dental Materials, Vol. 37 (2021), e37–e46]
https://doi.org/10.1016/j.dental.2020.10.009
E-mail: narut[at]material.tohoku.ac.jp
Key Words: Titanium alloys, visible-light responsive, two-step thermal oxidation, antibacterial activity
To avoid risk of infections associated with dental implants, thermal oxidation processes for practical dental Ti alloys were studied for both high bonding strength and antibacterial properties in visible light. Two-step thermal oxidation, comprising carburization (first step of treatment: in Ar-1%CO gas) and subsequent oxidation (second step of treatment: in air), was conducted on commercially pure (CP) Ti, Ti-6Al-4V (Ti64), and Ti-6Al-7Nb (Ti67) alloys to form TiO2 layers. Their bonding strengths and antibacterial properties against Escherichia coli (E. coli) in visible light (λ ≥ 400 nm) were evaluated. TiO2 layers formed on each metal were composed of anatase and/or rutile. Anatase fraction and carbon concentration in the layers decreased with increasing temperature in the second step of treatment. Antibacterial properties of the TiO2 layers were dependent on the temperature in the second step of treatment. An approximate antibacterial activity value of 2 (killing ∼99% bacteria) was obtained when the temperatures in the second step of treatment were 673 and 773 K for CP Ti, 773 K for Ti64, and 773 and 873 K for Ti67. Bonding strength between the substrate and TiO2 layers formed at 773 K in the second step of treatment exceeded 80 MPa and was independent of substrate type.
TiO2 layers, possessing both high bonding strength and excellent antibacterial properties, were successfully formed on practical dental Ti alloys via two-step thermal oxidation.