Research On Biocompatibility And Erosion-corrosion Resistance Of Nanocrystalline Of Ta₂O₅ Coating

With the gradual improvement of people's material life,it has become a trend that more and more people have been paid attention to their health and medical conditions?hospital level,the level of doctors,the application of medical devices,etc.?.Nowadays,the population aging process,the frequent occurrence of traffic accidents,the damage of terrorist attacks and religious problems have spawned the hot market of medical devices.As a substitute material for human body,the titanium alloy with good mechanical properties and corrosion resistance has been widely used.But recent research shows that the process of implant material failure is complex that on the one hand micro friction effect cause material surface debris ascribing its high friction coefficient and on the other hand surrounding tissue inflammation originate from decreasing corrosion resistance leading to the release of harmful ions.In the past decades,scientists have promoted surface osseointegration of titanium alloy by different surface modification technologies.the antibacterial properties and cell compatibility of materials also play an important role in the clinical application.In this context,we hope that the surface modification method can improve the problems faced by titanium alloy in biological materials.At the same time,the erosion corrosion resistance of the coating is preliminarily studied in the simulated sea water with the requirements for the mechanical equipment in the ocean becoming more and more strict as the exploration of the ocean getting deeper and deeper.A double cathode glow plasma sputtering deposition technique was used to prepare a Ta₂O₅ nanocrystalline coating on the surface of a Ti6Al4V wafer with a diameter of 10 mm thickness of 30 mm.The excellent performance is achieved in combination with the coating and thetitanium alloy.The main test results of the prepared nanocrystalline coating are shown below:1)the preparation coating was Ta₂O₅ nanocrystalline confirmed by XPS and XRD detection methods.The coatings with thickness of 32?m exhibit extremely dense an homogeneous structure without any obvious defects,and appear to be well adhered to the Ti-6Al-4V alloy substrate by SEM test.the AFM test showed that the surface roughness of the coating is 6nm,TEM analysis showed that the grain size of the coating is composed of 13nm equipped grain shape.Nanoindentation tests show the hardness and elastic modulus of the coatings Ta₂O₅ are obviously higher than those of Ti-6Al-4V alloy;The scratch tests suggest that the adhesion strength of the coatings to Ti-6Al-4V alloy substrate is higher than that of wide acceptance for engineering applications?30 N?.2)Electrochemical impedance and potentiodynamic polarization tests show coating significantly improve the corrosion resistance of Ti-6Al-4V alloy in Hank's and PBS solution,and After immersion of 1?3 and 14 days in simulated body fluid,the surface of the coating was covered more carbonate-containing bone-like apatite layer than Ti-6Al-4V alloy.At the same time,the Mott-Schottky test show that the prepared coating was n type semiconductor.the test carrier concentration in the two solutions was less than that of the uncoated Ti-6Al-4V.The zero point charge test shows that the coating has a stronger rejection of Cl^-than the Ti-6Al-4V.3)Cells culture tests revealed that the coating is more beneficial to the adhesion and proliferation of NIH-3T3 cells compared to the uncoated Ti–6Al–4V.Antibacterial,dynamic clotting time and hemolysis tests show that the nanocrystalline Ta₂O₅ coatings exhibit good antibacterial property and hemocompatibility.4)the corrosion properties of the Ti-6Al-4V alloy and nanocrystalline Ta₂O₅ coating under the scouring condition were compared.The results showed that the Ti-6Al-4V alloy has the critical velocity and weight loss rate are mainly caused by corrosion weightlessness while scouring was supplemented.The coating has no critical speed at this scouring speed and the weightlessness rate was less than the substrate whatever were the weight loss rate of scouring,the weight loss rate of pure corrosion and the interaction between them.