Zn- or Cu-Containing CaP-Based Coatings Formed by Micro-arc Oxidation on Titanium and Ti-40Nb Alloy: Part I-Microstructure, Composition and Properties.

Ekaterina G Komarova,Mariya B Sedelnikova,Igor A Khlusov,Matthias Epple,Yurii P Sharkeev,Oleg Prymak,Konstantin A Prosolov

doi:10.3390/ma13184116

Abstract

Zn- and Cu-containing CaP-based coatings, obtained by micro-arc oxidation process, were deposited on substrates made of pure titanium (Ti) and novel Ti-40Nb alloy. The microstructure, phase, and elemental composition, as well as physicochemical and mechanical properties, were examined for unmodified CaP and Zn- or Cu-containing CaP coatings, in relation to the applied voltage that was varied in the range from 200 to 350 V. The unmodified CaP coatings on both types of substrates had mainly an amorphous microstructure with a minimal content of the CaHPO4 phase for all applied voltages. The CaP coatings modified with Zn or Cu had a range from amorphous to nano- and microcrystalline structure that contained micro-sized CaHPO4 and Ca(H2PO4)2·H2O phases, as well as nano-sized β-Ca2P2O7, CaHPO4, TiO2, and Nb2O5 phases. The crystallinity of the formed coatings increased in the following order: CaP/TiNb < Zn-CaP/TiNb < Cu-CaP/TiNb < CaP/Ti < Zn-CaP/Ti < Cu-CaP/Ti. The increase in the applied voltage led to a linear increase in thickness, roughness, and porosity of all types of coatings, unlike adhesive strength that was inversely proportional to an increase in the applied voltage. The increase in the applied voltage did not affect the Zn or Cu concentration (~0.4 at%), but led to an increase in the Ca/P atomic ratio from 0.3 to 0.7.

Highlights

During the most recent couple of decades, an outstanding amount of studies, advancing the area of biocompatible material production, has been conducted [1,2]
The samples used in this study were cut from billets of commercial pure titanium (Grade 2, VSMPO-AVISMA Corp., Verkhnaya Salda, Russia) and Ti-40 wt% Nb (Ti-40Nb) alloy in the form of plates of 10 × 10 × 1 mm3 in size
Earlier in the paper [39] it has been illustrated that the oxides of titanium and niobium are typically localized in the interface layer between the metal substrate and the coating

Summary

Introduction

During the most recent couple of decades, an outstanding amount of studies, advancing the area of biocompatible material production, has been conducted [1,2]. An ever-increasing number of cutting-edge biomedical innovations, materials, and items are being created, including metal-based implants and biocompatible coatings, which could replace damaged bones and foster healing. Factors, such as tissues, cellular and biomechanical compatibility are of utmost importance for the functional reliability of such materials. The first approach is the development of metallic materials that would be biomechanically compatible with a host tissue preventing possible degenerative processes in bones or even decreasing the risk of revision surgery [1,2,3,4]. The second approach is the development of advanced calcium phosphate (CaP) coatings that could be tailored, in terms of compositional, structural, and morphological features, enhancing the osteogenic potential in the post-operative period [2,5,6,7]

Methods

Results

Conclusion