One-step Synthesis Of A Hierarchical Micro/Nanostructured Metal-Ceramic Nanocomposite Coating With Enhanced Antibacterial Activities

In order to improve the antibacterial and microbial corrosion resistance of Ti-6Al-4V alloy,this subject creatively designed a metal/ceramic dual-phase composite coating prepared on the surface of Ti-6Al-4V alloy by double-cathode glow discharge deposition.Two coatings with different surface morphologies were obtained through composition and process control,named A and B composite coatings.The experiments mainly analyzed the phase composition and microstructure of the two coatings by means of XRD,SEM,EDS and TEM,and related tests were performed on the mechanical properties such as hardness and elastic modulus.The antibacterial properties of the coatings were mainly tested by four kinds of bacteria/fungi,such as S.aureus,E.coli,Salmonella,and Candida albicans,and the effects of surface morphology and light on the antibacterial properties were analyzed.Finally,the electrochemical resistance of the two coatings and Ti-6Al-4V alloy in the SRB bacterial liquid environment were analyzed by electrochemical test methods such as electrochemical impedance spectroscopy and dynamic potential polarization curve.The results show that both coatings consist of a metal solid solution phase and a spinel ceramic phase.The metal phase mainly contains Cu,Co,Ni,and a small amount of Fe elements,while the ceramic phase is mainly Fe(Al,Cr)₂O₄,and the relative mass fraction of metal phase in coating A is higher than coating B.The surface morphology of both coatings consists of a micron-scale"bamboo-like"structure on the surface and a dense layer on the bottom,with a total thickness of about30?m.The surface of the"bamboo-like"structure of the A coating contains a large number of nano-sized fine protruding particles,while the"bamboo-like"surface of the B coating is relatively smooth,and no obvious nanoparticles are observed.The hardness and elastic modulus of the two coatings are two to three times that of the Ti-6Al-4V alloy,which can provide certain protection to the substrate in engineering applications.Both of the contact angle test and the UV/Vis/NIR diffuse reflection test of the coating before and after the abrasive polishing process prove that coatings with micron plus nano composite structures on the surface can form higher hydrophobic angles and absorbances.In the contact antibacterial experiment,the A and B coatings have strong killing ability against four kinds of bacteria.After one hour of contact,they can kill more than 99.9%of the bacteria/fungi on the surface.The antibacterial performance of the coating mainly comes from the bactericidal effect of Cu ions,and the photothermal sterilization produced by light and the physical sterilization of the surface structure can greatly increase the antibacterial efficiency of the coating.Among them,the A coating with nanostructure has better photothermal antibacterial and structural antibacterial performance than the B coating under the same conditions.Electrochemical tests after immersing in SRB for different periods of time show that the two composite coatings have higher resistance and lower self-corrosion current density,and the performance of the A coating with a higher hydrophobic angle is slightly better than the B coating.At the same time,the results of the comparative observation of the corrosion morphology also proved that the A and B coatings can inhibit the adhesion and growth of SRB bacteria on the surface,thereby significantly improving the microbial corrosion resistance of Ti-6Al-4V alloy.