Preparation And Antibacterial Properties Of Ag Coating On Titanium Alloy Surface

Titanium alloys are widely used in medical implants due to their excellent mechanical properties and biocompatibility.However,the poor corrosion resistance and lack of antibacterial properties of titanium alloys limits their development in the biomedical field.As a broad-spectrum antibacterial agent,silver(Ag)has good mechanical properties and antibacterial properties.The preparation of Ag coating on the surface of titanium alloy is of great significance for the functional antibacterial treatment of titanium alloy.In order to improve the antibacterial properties of titanium alloy Ti6Al4 V,on the basis of magnetron sputtering technology,this paper uses a combination of simulation and experiment to improve the structure and properties of the coating by optimizing the target-substrate distance parameters.The Ag coating was prepared on the surface of titanium alloy Ti6Al4 V,and the microstructure and properties of the coating was systematically studied and analyzed to verify the feasibility of the scheme and provide guidance and ideas for high-quality sputtering coating process.The main research contents include :1)The glow discharge phenomenon in sputtering coating was simulated by COMSOL software,and the influence of target-substrate distance on the ion parameters of substrate surface during discharge was studied.The simulation results show that the ion density increases first and then decreases with the decrease of target-substrate distance.The ion temperature and ion flux gradually increases,and reach the maximum when the target-substrate distance is 50 mm,that is,the coating efficiency is the largest.2)Five groups of Ag coatings(A1,A2,A3,A4 and A5)were prepared on the surface of titanium alloy Ti6Al4 V by magnetron sputtering with target-substrate distance parameters of 50,80,110,140 and 170 mm,respectively,and the simulation results were verified.The results show that the surface of all coatings is smooth and dense,Ag exists in the form of nanoparticles,and the main phases of the coatings are Ag and Ti.With the decrease of the target-substrate distance,the crystallinity of Ag gradually becomes better,and the content gradually increases.When the target-substrate distance is 50 mm(sample A1),the Ag content reaches the maximum,and the mass fraction is 100 %.3)The mechanical properties of the coating were tested by nanoindentation experiments.The results show that the elastic modulus and hardness of the coating gradually increases with the decrease of the target-substrate distance,showing better mechanical properties and wear resistance.The mechanical properties of sample A1 are the best,and the mechanical properties of sample A5 are the worst.4)The corrosion resistance of the coating was tested by electrochemical corrosion experiments.The results showed that with the decrease of the target-substrate distance,the self-corrosion potential of the coating became higher,the corrosion current density became smaller,and the corrosion resistance of the coating was better.Among them,sample A1 has the best corrosion resistance,and sample A5 has the worst corrosion resistance.5)The antibacterial properties of the coating were tested by in vitro active antibacterial experiments.The results showed that the antibacterial rate of the coating against Escherichia coli and Staphylococcus aureus was more than 99.9 %,and the antibacterial effect of the coating against Escherichia coli was better than that of Staphylococcus aureus.In addition,with the decrease of the target-substrate distance,the antibacterial performance of the coating will be enhanced,and the antibacterial performance of sample A1 is the best.