| Due to their excellent biocompatibility with other biomedical metal materials,mechanical properties and corrosion resistance,titanium and titanium alloys are widely used in the medical field to manufacture medical devices,artificial joints and implants that can be implanted in the human body for a long period of time.However,its wear resistance is poor.This article starts with improving both the wear mechanism and mechanical properties of the material to improve the wear resistance of titanium.For the former,the most novel laser surface texturing technology?LST?has been used;for the latter,nitrogen ion implantation technology?NII?,witch is capable of cleaning and high-speed production,has been used.The substrate used here is an industrial pure titanium,TA2.The Nd:YAG pulsed laser was used to prepare three types of textured specimens with dimple,line and grid pattern on the surface of TA2.The surface phase composition was analyzed by X-ray diffractometer?XRD?.The hardness before and after LST treatment was measured with a microhardness tester and the morphological features were evaluated with a scanning electron microscope?SEM?.The wear tester was used to evaluate the friction and wear properties of the textured specimens under dry and wet grinding conditions?simulated body fluid,m-SBF?,respectively.Finally,it is concluded that the three types textures,point,line and grid,can all reduce the friction coefficient to different extents and t he optimum process parameter for wear resistance of three types of textured specimens were obtained,namely areal density of 25%for dimple texture sample,and spacing of 900?m for the line and grid texture sample,respectively.For the dry grinding,wear rates of the three types of textured specimens were 1.14×10-3mm3/N m,0.71×10-3mm3/N m,and 1.51×10-3mm3/N m,respectively.Compared to TA2 sample,their wear resistance increased by 70%,170%,and 28%,respectively;For wet grinding,their wear rates were 1.37×10-3mm3/N m,1.25×10-3mm3/N m and 1.70×10-3mm3/N m,respectively.Compared to TA2 sample,their wear resistance increased by 36%,50%,and 9%,respectively.Among them,wear rate of TA2 specimen for the dry and wet grinding processes were 1.94×10-3mm3/N m and1.87×10-3mm3/Nm,respectively.Based on three kinds of textured samples,the wear resistance of substrate TA2 was studied by two-step LST/NII treatment.It was found that the wear resistance of the textured specimens with NII treatment was further improved.The results showed that the wear rate in wet grinding processes of the three kinds of texture samples with the above-mentioned optimum process parameters,were 0.37×10-3mm3/N m,0.71×10-3mm3/N m and 0.19×10-3mm3/N m,respectively and the corresponding wear resistance increased by 430%,160%and 880%,respectively.In addition,the corrosion resistance of the three kinds of textured samples was well improved by electrochemical test results.The total impedances corresponding to the three optimal parameters are 975.9k?/cm2,1628.6k?/cm2 and 1786.6k?/cm2,respectively.The corresponding corrosion current densities are 23.993nA/cm2,207.789nA/cm2 and 153.689nA/cm2,respectively.Compared to the untreated TA2 sample with the total resistance of 405.7k?/cm2 and corrosion current density of 351.192nA/cm2,the corrosion resistance after NII treatment is significantly improved.In a word,the texture pattern with dimple,line and grid all play a role of storing wear debris,effectively reducing the cutting effect of wear particle s on the surface,thereby improving the wear resistance of the surface.At the same time,due to the existence of heat-affected zone in the process of texturing,the edge hardness of the texture is improved to a certain extent,which improves the wear resistance of the material surface to some extent.After NII treatment,a hard nitrided layer is formed on the surface,which further improves the hardness and wear resistance.In addition,the existence of the nitride layer effectively prevents the ions in the solution from corroding the substrate material,thereby improving the corrosion resistance. |
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