Study On Friction And Wear And Mechanical Properties Of TA3 Implants Strengthened By Laser Shock

As a common medical metal material,medical TA3 pure titanium has been widely studied and applied in the field of medicine.However,the mechanical conditions and physiological environment in human body are more complex,and the failure forms such as corrosion,wear and fracture are easy to occur after the implant is in service for a long time,which causes extremely serious physiological and mental trauma to the patients.As a result,it is very important to improve the corrosion resistance and mechanical properties of pure titanium in medical TA3.Laser impact strengthening technology(LSP)is a new advanced technology to strengthen the surface of materials by using the force effect of shock wave.Different from conventional modification techniques,it has the advantages of changing the microstructure of metal materials surface and producing larger and deeper residual compressive stress,which can greatly enhance the wear resistance and mechanical properties of metal.In this paper,TA3pure titanium implant for medical use was taken as the research object.It was strengthened by laser shock treatment,and the influence of different laser shock parameters on the surface integrity,wear resistance and mechanical properties of TA3 pure titanium implant was discussed through surface integrity test,friction and wear test and tensile test at room temperature.The main research contents of this paper are as follows:(1)The laser shock strengthening experiment of medical TA3 pure titanium implant and the study of its surface integrity.The combination of process parameters with different laser pulse energy and laser shock times is used to perform laser shock strengthening treatment on medical TA3 pure titanium samples,with the aid of stress testers,microhardness testers,surface profilers,white light interferometers,and metallurgical microscopes,the surface and depth residual stress,microhardness,roughness,surface morphology and micro properties of medical TA3 pure titanium implants before and after laser shock strengthening were discussed.The experimental results show that the surface grains of medical TA3 pure titanium are refined and evenly distributed by different laser energy and shock times,and the residual stress,microhardness and roughness are increased.The maximum residual compressive stress is-401.3MPa.With the increase of depth,the residual stress and hardness values gradually decrease and finally keep consistent with the matrix,in which the deepest residual compressive stress affected layer is up to 960?m,and the deepest hardened layer is up to 1100?m.(2)Research on the abrasion resistance of medical TA3 pure titanium implants strengthened by laser shock.Using modified SBF simulated body fluid as lubricant,the wear experiment of LSP samples was carried out by using MSR-2T equipment.The effects of laser impact enhancement on the wear performance of medical TA3 implants were studied by investigating the changes of typical characteristic parameters and features such as the width and depth of pure titanium wear marks,wear volume,friction coefficient and wear mark morphology.The study found that:under the lubrication state of the modified SBF simulated body fluid,the sample's wear mark width and depth,wear volume,wear rate and friction coefficient all show a downward trend with the enhancement of laser pulse energy and laser impact strengthening times.Among them,reduction of abrasion width from 0.839 mm to 0.724mm,the maximum reduction was 13.71 percent.The depth of the mark was reduced from0.0204 mm to 0.011mm,the maximum reduction was 46.08 percent.The wear volume decreased from 0.11415 mm~3 to 0.0531 mm~3,the maximum reduction was 53.48 percent.The maximum reduction of the wear rate is 53.51%;the maximum reduction of the average friction coefficient is 37.68%,showing a good anti-friction effect.They can be seen that laser shock strengthening treatment can significantly improve the friction and wear performance of medical TA3 pure titanium in the modified SBF simulated body fluid environment.(3)Research on the mechanical properties of medical TA3 pure titanium implants strengthened by laser shock.The tensile test was carried out on#0?#5 tensile specimens with the help of GHS50K universal testing machine,and the evolution of fracture morphology of tensile specimens after LSP treatment with different laser pulse energy and different laser shock times was observed by SEM.Tensile test results show that with the increase of LSP energy and number,the room temperature tensile strength of pure TA3 titanium increases,that is,the tensile property of pure TA3 titanium is better,but the plasticity is decreased.The maximum tensile strength increased from 468.2MPa to 521.6MPa,with an increase of 11.41%.The elongation rate decreased from 46.88%to 36.01%,a decrease of 23.19%.The tensile fracture morphology analysis results show that there is a large amount of tear in the original sample fracture.Split edges,dimples and micropores,and the dimples are unevenly distributed,large in size and deep in depth.After laser shock strengthening treatment with different energy and times,the dimple distribution on the fracture surface of medical TA3 pure titanium is more uniform,the size becomes smaller and the depth becomes shallower;the size of the micropores also becomes smaller,and the depth becomes shallower.Laser shock strengthening treatment can significantly improve the mechanical properties of medical TA3 pure titanium implants.