Assessment of applied voltage on the structure, pore size, hardness, elastic modulus, and adhesion of anodic coatings in Ca-, P-, and Mg-rich produced by MAO in Ti-25Ta-Zr alloys

Author(s)

Kuroda, Pedro Akira Bazaglia ; Rossi, Mariana Correa ; Grandini, Carlos Roberto ; Afonso, Conrado Ramos Moreira

• Document type: Journal article
• Source: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T; v. 26, p. 14-pg., 2023-08-31.

Abstract

This work aims to modify the surface of the Ti-25Ta-xZr (x 1/4 0, 25, and 50 wt%) system alloys through micro-arc oxidation (MAO) to incorporate calcium, phosphorus, and magnesium ions in the oxidized layer deposited. The MAO surface modification was performed by changing the limited voltage applied to system (200, 250, and 300V). Structural characterizations by X-ray diffraction and X-ray photoelectron spectroscopy showed that the formed MAO coatings comprise TiO2, Ta2O5, ZrO2, and CaCO3 oxides. Voltage inhibits the formation of Ta2O5 and CaCO3 phases and decreases the incorporation capacity of Ca, P and Mg ions. The MAO coatings' topography, thickness, and roughness, analyzed by scanning electron microscopy and confocal microscopy techniques, showed that increasing the voltage tends to increase pore sizes and reduces film thickness; conversely, it decreases the number of pores per mm2. Regarding hardness and elastic modulus, adding Zr increases the MAO coating's hardness due to the formation of ZrO2. However, increasing the voltage decreases the MAO coatings' hardness due to the formation of the compound CaCO3. The MAO process increased the elastic modulus of the Ti-25Ta-xZr bulk alloys. Finally, the adhesion of the films was analyzed by the Rockwell-C adhesion test. The results showed a good adhesion of MAO coatings to Ti-25Ta-xZr substrates.& COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). (AU)

• FAPESP's process: 18/18293-8 - Titanium alloys: phase transformations and additive manufacturing applied to obtaining functionally graded materials
• Grantee: Rubens Caram Junior
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 19/26517-6 - Influence of the microstructure and phases on surface functionalization of beta Ti-25Ta-xZr- alloys system
• Grantee: Pedro Akira Bazaglia Kuroda
• Support Opportunities: Scholarships in Brazil - Post-Doctoral