Research On Laser Surface Texturing/electrophoretic Deposition Composite Process Of Titanium Alloy Implant

Ti6Al4V titanium alloy materials are widely used in biomedical fields,especially in orthopedic implants,due to their good corrosion resistance,low cytotoxicity and excellent mechanical properties.However,as a biologically inert material,titanium alloy lacks osteogenic properties,which limits the organic bonding between implants and bone tissue.In addition,with the increasing aging of the population,there is a higher demand for the biological properties of titanium implants in the market.It has been shown that the introduction of certain microstructures on the implant surface is beneficial for cell attachment and proliferation,and improves the osteogenic properties of the material;the biocompatibility of the implant can be further improved by introducing a surface coating.Therefore,this paper proposes a surface modification method based on a composite process of laser micro-modeling and electrophoretic deposition to improve the surface biological properties of implants.The research in this paper is as follows.(1)A numerical simulation study of nanosecond laser surface micromodeling processing of titanium alloys was carried out.A finite element model of laser ablation of titanium alloy was constructed,and the crater processing and groove processing processes were analyzed with two-dimensional and three-dimensional models,respectively.The analysis of the calculated results revealed that the material was continuously removed due to the heat accumulation with the increasing number of pulses.The pulse frequency and the movement speed of the heat source have an effect on both the heat accumulation and the pulse overlap rate,thus affecting the results of the micro-modeling process.(2)Laser ablation of micro-pits and grooves was carried out to investigate the influence of laser parameters on the dimensions of the processed microstructure shapes.The results showed that the number of laser scans,the scanning speed and the frequency of the laser had an influence on the results of ablation,and the different selection of parameters would change the dimensions and quality of the processed shapes.(3)An electrophoretic deposition experimental setup was built to carry out the electrophoretic deposition of graphene oxide on the surface of titanium alloy.The results show that the deposition time,solution concentration and power supply voltage intensity are the three main factors affecting the quality of the deposited layer,and there is a solution concentration threshold,and the electrophoretic deposition reaction can only occur smoothly when the solution concentration exceeds this threshold.When electrophoretic deposition was performed on the substrate after micro-modeling,it was found that the thickness of the deposited layer and the substrate morphology also had an effect on the morphology of the deposited layer.(4)The surface properties of the processed samples were characterized,including:the influence law of surface morphology on wettability,X-ray diffraction and Raman spectroscopy studies.The results obtained from the in vitro biological experimental study of the samples processed by the composite process demonstrated that the surface bioactivity was significantly increased after the composite process and the microshaped patterns could guide the directed cell proliferation and differentiation.