Multipurpose surface modification of PEO coatings using tricalcium phosphate addition to improve the bedding for apatite compounds

Recently, Mg alloys have found appealing biomedical applications because of properties such as biode-gradability and biocompatibility. However, the full potential of Mg alloys has yet to be exploited as implant materials due to insignificant corrosion resistance and inadequate support to contain apatite compounds. This study presents a novel method to prepare and modify plasma electrolytic oxidation (PEO) coatings facilitating the formation of apatite compounds on the surface without compromising corrosion protection. We prepared calcium-phosphate PEO coatings in a phosphate-based electrolyte benefiting from introducing tricalcium phosphate (TCP) salt as an additive. The composition and surface morphology of coatings pro-duced with the addition of 1-4 g/l TCP were studied using EDS, XRD, FT-IR, and FE-SEM. Moreover, coatings' surface roughness and wettability were evaluated. We investigated the electrochemical behavior of coatings exposed to simulated body fluid (SBF) at four intervals (1 h, 1, 3, and 7 days) using electrochemical im-pedance spectroscopy (EIS). We realized that the coating produced with 4 g/l TCP addition offers a modified surface supporting the bedding for precipitation of apatite compounds and demonstrating significant corrosion protection. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

A novel method of preparing and modifying plasma electrolytic oxidation (PEO) coatings by adding tricalcium phosphate (TCP) in a phosphate-based electrolyte was presented in this study. The coatings with addition of 4 g/l TCP demonstrated a modified surface supporting the precipitation of apatite compounds and significant corrosion protection when exposed to simulated body fluid (SBF).