Ceramic coating on Mg alloy for enhanced degradation resistance as implant material

Abstract

Magnesium (Mg) alloys display very appealing characteristics, including biocompatibility, bioactivity, biodegradability, lightweightness, and a similar density to cortical bone tissue, but they have some constraints, such as inappropriate corrosion and degradation resistance, which lead to failing early mechanical strength. Therefore, calcium phosphate (CaP)-based ceramic coating like hydroxyapatite (HA) coating is fabricated on the anodization-induced surfaces of pure Mg and ZK41 Mg alloy specimens to overcome those constraints in medical applications. In mechanical integrity like microhardness, adhesion strength tests demonstrated that HA coated ZK41 and Mg specimens significantly increased Vickers' hardness number (about 2 times) compared to unmodified substrates and had greater adhesion strength in comparison with the anodization-induced layer, respectively. In the in vitro immersion test, the HA-coated samples showed plate-like and needle-like crystal formations. This provided more surface area, which improved the corrosion and degradation resistance characteristics. As a consequence, the least amount of weight loss has occurred.Additionally, the anodized (AN) Mg, HA coated Mg, untreated ZK41, and anodized ZK41 samples all have higher corrosion rates than the HA coated ZK41 (0.018 mm/year). Cell viability of HA coated Mg and its alloy ZK41 was comparatively high, which ensures biocompatibility as an implant material. Therefore, HA coatings for Mg and ZK41 alloys for clinical applications could be more promising. In this study, ZK41 Mg alloy has been used as an inventive substrate for HA coating in place of the prior Mg alloys, with the intention of addressing the earlier drawbacks.