A novel iron/zinc phosphate layered composite coating on Zn-0.5Li alloy for guided bone regeneration membrane applications

Zinc (Zn) alloys currently demonstrate great potential and advantages as new biodegradable metal materials for guided bone/tissue regeneration (GBR/GTR) membranes. However, the uneven corrosion of Zn alloys and the release of excess Zn²⁺ during degradation result in local cytotoxicity, limiting their practical applications. In this study, filtered cathode vacuum arc (FCVA) technology and chemical methods were utilized to fabricate a layered composite coating of iron (Fe)/phosphate zinc (ZnP) on the surface of a Zn-0.5 wt%Li alloy. The microstructure, bonding strength, water contact angle, tribological properties, corrosion resistance, and biocompatibility of the coated samples were comprehensively investigated. The results demonstrate that the Fe/ZnP layered composite coating exhibits a uniform and dense flower-like morphology on the surface with approximately 7% higher bonding strength (68.91 MPa) compared to single ZnP coating directly applied to the Zn–Li alloy substrate. Furthermore, the Fe/ZnP composite coating sample demonstrates superior wear resistance and corrosion resistance (1.72 μm/year) when compared to the Zn–Li alloy substrate; additionally, it induces a shift in corrosion mechanism from local corrosion to uniform corrosion. Furthermore, the Fe/ZnP composite coating sample showed better cell viability than the substrate material. Moreover, the hemolysis rate of the coating sample was 0.175%, indicating that it also has excellent blood compatibility. These findings indicate that the Fe/ZnP composite coating effectively mitigates uneven corrosion in Zn–Li alloy while enhancing its biocompatibility—suggesting potential applications in future bone implant materials.