Preparation And Properties Of ZrO₂-HA Composite Coating On The Surface Of Ti-6Al-4V Alloy

Medical titanium alloys（Ti-6Al-4V alloy）are widely used for the replacement of human hard tissues due to its excellent mechanical properties and good biocompatibility.However,its poor biological activity and toxic metal Al³⁺and V^-ions released into the surrounding tissues limit its application.Hydroxyapatite（HA）,which has similar chemical properties to natural bones,good biocompatibility and osteoinduction,is a very important inorganic component of human and animal bones.But HA has poor mechanical properties such as low strength,high toughness,and high brittleness,which limits its application in the biomedical field.Coating technology can obtain advantages of two materials,which is one of important way to solve the problem.This paper mainly uses electrochemical deposition and hydrothermal treatment to prepare ZrO₂-HA composite coatings on the surface of Ti-6Al-4V substrate.It was studied that the morphology,composition,structure and corrosion resistance of ZrO₂-HA composite coating.The best process parameters are obtained.On this basis,the biocompatibility of ZrO₂-HA composite coating prepared by optimal process parameters was further investigated.The results are shown as follows:（1）The morphology,composition,structure,crystallinity,bonding force and the electrochemical behavior of ZrO₂-HA composite coatings are affected by pulse deposition time.The ZrO₂-HA composite coating,which is prepared by 1.5 h,has the uniform and dense morphology,the supreme crystallinityand binding force.Electrochemical experiments show that the ZrO₂-HA composite coatingprepared by 1.5 h has the smallest self-corrosion current density and the largest capacitive arc radius in the two corrosion solutions of SBF and DMEM.The immersion experiment shows that the ZrO₂-HA composite coating has the smallest corrosion rate in SBF solution.（2）The morphology,composition,structure,crystallinity,bonding force and the electrochemical behavior of ZrO₂-HA composite coatings are affected by pulsecurrent intensities.The morphology of ZrO₂-HA composite coating is the uniform and the crystallinity of ZrO₂-HA composite coatingis the optimalwhen the current density is-2 m A.The bonding force between the ZrO₂-HA composite coating and the substrate is the highest.In the SBFand DMEM corrosion solution,the test of polarization curve indicates that the composite coatinghasthe lowest self-corrosion current density.The results of impedance spectroscopy（EIS）demonstrate that ZrO₂-HA composite coating has the largest capacitive reactance arc radius and resistance value.After soaking in SBF solution for 13 weeks,the experiment resultsindicate that the corrosion rate of the ZrO₂-HAcomposite coating is the smallest.（3）Compared with the Ti-6Al-4V alloy,the surface of the ZrO₂-HA composite coating is non-cytotoxic.The ZrO₂-HA composite coating significantly improves the adhesion,spreading and proliferation of osteoblasts.