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Article

Exfoliation Resistance, Microstructure, and Oxide Formation Mechanisms of the White Oxide Layer on CP Ti and Ti–Nb–Ta–Zr Alloys

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Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan
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Graduate School of Engineering, Nagoya Institute of Technology, Gokisocho, Showa Ward, Nagoya, Aichi 466-8555, Japan
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Institute for Protein Research, Osaka University 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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Graduate School of Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku Ward, Nagoya, Aichi 468-8502, Japan
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Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
*
Author to whom correspondence should be addressed.
Academic Editor: Csaba Balázsi
Materials 2021, 14(21), 6599; https://doi.org/10.3390/ma14216599
Received: 15 September 2021 / Revised: 27 October 2021 / Accepted: 29 October 2021 / Published: 2 November 2021
(This article belongs to the Section Biomaterials)
We found that specific biomedical Ti and its alloys, such as CP Ti, Ti–29Nb–13Ta–4.6Zr, and Ti–36Nb–2Ta–3Zr–0.3O, form a bright white oxide layer after a particular oxidation heat treatment. In this paper, the interfacial microstructure of the oxide layer on Ti–29Nb–13Ta–4.6Zr and the exfoliation resistance of commercially pure (CP) Ti, Ti–29Nb–13Ta–4.6Zr, and Ti–36Nb–2Ta–3Zr–0.3O were investigated. The alloys investigated were oxidized at 1273 or 1323 K for 0.3–3.6 ks in an air furnace. The exfoliation stress of the oxide layer was high in Ti–29Nb–13Ta–4.6Zr and Ti–36Nb–2Ta–3Zr–0.3O, and the maximum exfoliation stress was as high as 70 MPa, which is almost the same as the stress exhibited by epoxy adhesives, whereas the exfoliation stress of the oxide layer on CP Ti was less than 7 MPa, regardless of duration time. The nanoindentation hardness and frictional coefficients of the oxide layer on Ti–29Nb–13Ta–4.6Zr suggested that the oxide layer was hard and robust enough for artificial tooth coating. The cross-sectional transmission electron microscopic observations of the microstructure of oxidized Ti–29Nb–13Ta–4.6Zr revealed that a continuous oxide layer formed on the surface of the alloys. The Au marker method revealed that both in- and out-diffusion occur during oxidation in Ti–29Nb–13Ta–4.6Zr and Ti–36Nb–2Ta–3Zr–0.3O, whereas only out-diffusion governs oxidation in CP Ti. The obtained results indicate that the high exfoliation resistance of the oxide layer on Ti–29Nb–13Ta–4.6Zr and Ti-36Nb-2Ta-3Zr-0.3O are attributed to their dense microstructures composing of fine particles, and a composition-graded interfacial microstructure. On the basis of the results of our microstructural observations, the oxide formation mechanism of the Ti–Nb–Ta–Zr alloy is discussed. View Full-Text
Keywords: titanium–niobium–tantalum–zirconium (Ti–Nb–Ta–Zr) alloy; oxide coating; biomaterials; exfoliation resistance; interfacial microstructure; nanoindentation; fretting wear titanium–niobium–tantalum–zirconium (Ti–Nb–Ta–Zr) alloy; oxide coating; biomaterials; exfoliation resistance; interfacial microstructure; nanoindentation; fretting wear
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MDPI and ACS Style

Miura-Fujiwara, E.; Yamada, S.; Mizushima, K.; Nishijima, M.; Watanabe, Y.; Kasuga, T.; Niinomi, M. Exfoliation Resistance, Microstructure, and Oxide Formation Mechanisms of the White Oxide Layer on CP Ti and Ti–Nb–Ta–Zr Alloys. Materials 2021, 14, 6599. https://doi.org/10.3390/ma14216599

AMA Style

Miura-Fujiwara E, Yamada S, Mizushima K, Nishijima M, Watanabe Y, Kasuga T, Niinomi M. Exfoliation Resistance, Microstructure, and Oxide Formation Mechanisms of the White Oxide Layer on CP Ti and Ti–Nb–Ta–Zr Alloys. Materials. 2021; 14(21):6599. https://doi.org/10.3390/ma14216599

Chicago/Turabian Style

Miura-Fujiwara, Eri, Soichiro Yamada, Keisuke Mizushima, Masahiko Nishijima, Yoshimi Watanabe, Toshihiro Kasuga, and Mitsuo Niinomi. 2021. "Exfoliation Resistance, Microstructure, and Oxide Formation Mechanisms of the White Oxide Layer on CP Ti and Ti–Nb–Ta–Zr Alloys" Materials 14, no. 21: 6599. https://doi.org/10.3390/ma14216599

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