Development of graphene oxide/calcium phosphate coating by pulse electrodeposition on anodized titanium: Biocorrosion and mechanical behavior

In this work, graphene oxide (GO) reinforcement was used to improve the strength and fracture toughness of the calcium phosphate (CaP) coating applied on the anodized titanium using pulse electrodeposition. Based on the results, the CaP coating consisted of mixed phases of octa-calcium phosphate (OCP), dicalcium phosphate dehydrate (DCPD) and hydroxyapatite (HAp); however, compositing of this coating with GO caused deposition of the pure HAp phase. Moreover, the nanohardness and Young's modulus of the CaP-GO coating increased over 52% and 41%, respectively, as compared to those measured for the GO-free coating. An improvement of about 16% in the adhesion strength of the CaP coating composited with GO to the anodized titanium was also arisen from improving integrity, crystallinity and decreasing the Young's modulus mismatch of this coating with titanium substrate. Finally, uniformity in the microstructure and more biostability of the CaP-GO coating led to its better protection against the corrosion of anodized titanium.