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. 2025 Feb 21;18(5):955.
doi: 10.3390/ma18050955.

Effect of Bulk Phase Composition on the Growth of PEO Coatings on the Biomedical Ti-6Al-4V Alloy

José Roberto Ferreira Neto  1 , Rafael Parra Ribeiro  1 , Nilson Cristino da Cruz  1 , Elidiane Cipriano Rangel  1 , Bruna de Oliveira Pinto  2 , Jhuliene Elen Muro Torrento  2 , Carlos Roberto Grandini  2 , Ulisses Ferreira Kaneko  3 , Diego Rafael Nespeque Correa  2
Affiliations

Effect of Bulk Phase Composition on the Growth of PEO Coatings on the Biomedical Ti-6Al-4V Alloy

José Roberto Ferreira Neto et al. Materials (Basel). .

Abstract

This study investigated the effects of plasma electrolytic oxidation (PEO) treatment in a Ca- and P-rich electrolyte on the surface of the Ti-6Al-4V alloy with distinct α/β phase proportions previously induced by heat treatments. The results revealed that the α/β phase proportions were successfully altered by the heat treatment temperatures, forming α phase plates surrounded by β phase precipitates. PEO-treated samples exhibited a thick and microsized porous TiO2 coating in the anatase and rutile crystalline forms. The oxide layer was depleted by Al and V atoms, while Ca and P were gradually enriched along the coatings. Chemical analysis also indicated the absorption of water and organic molecules into the outer layer. PEO-treated samples had microscale roughness and thickness, hydrophilic behavior, and surface energy mainly formed by the dispersive component. The bulk's elastic modulus decreased with β phase precipitation, while the alloying elements directly influenced the Vickers microhardness. The corrosion tests indicated a stable and protective layer in the PEO-treated samples, showing better corrosion resistance than untreated ones. Overall, the findings indicated that the α and β phase proportion significantly impacts the mechanical properties, while the PEO treatment acts in the corrosion protection and surface aspects, suggesting that combining both approaches could be a powerful tool in biomedical applications.

Keywords: PEO; Ti-6Al-4V; biomaterials; corrosion; heat treatment; phase composition.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Processing route of the samples: (a) time–temperature plot and (b) the corresponding pseudo-binary phase diagram (adapted from [16]).
Figure 2
Figure 2
Current density vs. time plot for the Ti-6Al-4V samples in each condition.
Figure 3
Figure 3
Microstructure and the corresponding surface topography of the samples: optical (left) and SEM (right) images.
Figure 4
Figure 4
XRD profiles of the untreated (a) and PEO-treated (b) Ti-6Al-4V samples, with the corresponding zoomed-in view (c).
Figure 5
Figure 5
EDS analysis for PEO-treated Ti-6Al-4V samples.
Figure 6
Figure 6
Semi-quantitative EDS analysis for Ti-6Al-4V samples in all studied conditions.
Figure 7
Figure 7
FTIR results at high (a) and low (b) wavenumbers and Raman spectra (c) for PEO-treated Ti-6Al-4V samples.
Figure 8
Figure 8
XPS semi-quantitative results: survey spectrum (a) and corresponding chemical composition (b) for Ti-6Al-4V in all studied conditions.
Figure 9
Figure 9
XPS HR results for C1s (a), O1s (b), and Ti2p (c) for Ti-6Al-4V samples in all studied conditions.
Figure 10
Figure 10
Roughness and thickness for PEO-treated Ti-6Al-4V samples.
Figure 11
Figure 11
Wettability test: contact angle (a) and surface energy (b) for Ti-6Al-4V samples in all studied conditions. The dotted red line refers to the limit between hydrophilic and hydrophobic surfaces.
Figure 12
Figure 12
Selected mechanical properties for untreated Ti-6Al-4V samples.
Figure 13
Figure 13
OCP results: OCP vs. time plot (a) and average OCP value (b) for Ti-6Al-4V samples in all studied conditions.
Figure 14
Figure 14
PDP results for Ti-6Al-4V samples in all studied conditions.
Figure 15
Figure 15
EIS results: Bode plots for the untreated (a) and PEO-treatment (b) Ti-6Al-4V samples and the corresponding Nyquist plots in (c,d).
Figure 16
Figure 16
EEC diagrams of the EIS curves: (a) as-received sample; (b) HT 600, HT 800, HT 1000, and as-received PEO samples; (c) HT 600 PEO, HT 800, and HT 1000 PEO samples.
See this image and copyright information in PMC

References

    1. Elhadad A.A., Romero-Resendiz L., Rossi M.C., Rodríguez-Albelo L.M., Lascano S., Afonso C.R.M., Alcudia A., Amigó V., Torres Y. Findings and Perspectives of β-Ti Alloys with Biomedical Applications: Exploring beyond Biomechanical and Biofunctional Behaviour. J. Mater. Res. Technol. 2024;33:3550–3618. doi: 10.1016/j.jmrt.2024.09.248. - DOI
    1. Yang J., Song Y., Dong K., Han E.-H. Research Progress on the Corrosion Behavior of Titanium Alloys. Corros. Rev. 2023;41:5–20. doi: 10.1515/corrrev-2022-0031. - DOI
    1. Specification for Wrought Titanium-6Aluminum-4Vanadium ELI (Extra Low Interstitial) Alloy for Surgical Implant Applications (UNS R56401) ASTM International; West Conshohocken, PA, USA: 2013.
    1. Liu S., Shin Y.C. Additive Manufacturing of Ti6Al4V Alloy: A Review. Mater. Des. 2019;164:107552. doi: 10.1016/j.matdes.2018.107552. - DOI
    1. Pinto B.O., Torrento J.E., Grandini C.R., Galindo E.L., Pintão C.A.F., Santos A.A., Lisboa-Filho P.N., Pontes F.M.L., Correa D.R.N. Development of Ti–Al–V Alloys for Usage as Single-Axis Knee Prostheses: Evaluation of Mechanical, Corrosion, and Tribocorrosion Behaviors. Sci. Rep. 2023;13:4349. doi: 10.1038/s41598-023-31548-1. - DOI - PMC - PubMed

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