Study On Corrosion-wear And Coupling Behavior Of Medical Ti6Al4V Alloy By Laser Shock Peening

Currently,The most common medical metal material is the medical Ti6Al4 V alloy in the medical field.Corrosion,wear and their coupling behavior occur in the extremely complex human environment,which greatly reduces its service time.Therefore,it is urgent to improve its corrosion and wear resistance.Compared with traditional surface modification technology,Laser Shock Peening has high stability residual stress and microstructure,which is often used to improve the mechanical and biological properties of medical titanium alloys.In this paper,the medical Ti6Al4 V alloy was used as the research object to explore the corrosion-wear and its coupling mechanism.LSP experiments,corrosion-wear experiments,friction-wear experiments and electrochemical corrosion experiments were carried out to analyze the effects of different LSP parameters on the corrosion?wear and their coupling behavior of medical Ti6Al4 V alloy in modified SBF simulated body fluids.The anti-corrosion and wear mechanism of LSP were verified by experiments.The main research contents are as follows:1?Experimental study on LSP of medical Ti6Al4 V alloys.The effects of laser power density and number of LSP on surface integrity,such as surface roughness,residual stress in surface and depth direction,surface and cross-section hardness,were studied.The experimental results show that: with the increase of laser power density and impact times,the surface roughness,surface hardness and surface residual stress of medical Ti6Al4 V alloys increase.The maximum surface residual compressive stress is-804.7MPa the hardness and residual stress influence layer in depth direction gradually decrease,and the deepest can reach 0.5~0.7mm and reach 1.15 mmrespectively.2?Experimental study on corrosion-wear of medical Ti6Al4 V alloy specimens before and after LSP.MSR-2T electrochemical reciprocating friction-wear tester and CHI660 E electrochemical workstation were used in the experiment.At the same time,medical Ti6Al4 V alloy corrosion-wear experiments were carried out simultaneously in the modified SBF simulated body fluid.The experimental results show that the corrosionwear resistance of Ti6Al4 V alloy are improved significantly with the increase of laser power density and impact times.3 ? Based on the corrosion-wear experiments,the friction-wear experiments of medical Ti6Al4 V alloy specimens before and after LSP were carried out.The experimental results show that the friction coefficient of medical Ti6Al4 V alloy samples fluctuates in a small range,and the average friction coefficient,the width and depth of wear marks,the wear volume and the wear rate of medical Ti6Al4 V alloy samples are significantly reduced with the increase of laser power density and impact times,and the wear resistance of medical Ti6Al4 V alloy is significantly enhanced.4?Based on the experiments of corrosion-wear,the electrochemical corrosion of medical Ti6Al4 V alloy samples before and after LSP was studied.The electrochemical corrosion experiments of medical Ti6Al4 V alloy in modified SBF simulated body fluid were carried out on Zennium electrochemical workstation.The open circuit potential,polarization curve,electrochemical impedance spectroscopy and Tafel curve of medical Ti6Al4 V alloy were measured.The experimental results show that the corrosion thermodynamics and passivation state of medical Ti6Al4 V alloy reach the optimal stability.The passive state and uniform corrosion rate are the lowest.A denser surface passivation film is obtained,which improves the corrosion behavior of medical Ti6Al4 V alloy in modified SBF simulated body fluid.5?Compared with the friction-wear and electrochemical corrosion experiments,the friction coefficient,the width and depth of the wear scar,the wear amount and the wear rate of the LSP medical Ti6Al4 V alloy are higher than those of the friction-wear specimens,resulting in deeper furrows on the surface of the wear scar,which leads to pitting defects of adhesion scar and corrosion coupling the impedance resistance of corroded wear specimens decreases by three orders of magnitude,and the self-corrosive potential,the potential range and polarization resistance of passivation zone all decrease the maximum current densities of self-corrosive and passivation increase by 6.74 times and 58.8%,respectively It shows that corrosion accelerates wear and accelerates electrochemical corrosion.