Research On Preparation Of Titanium-Based Surface Micro-Nano With Coating Structure Composite And Biocompatibility

Titanium and its alloys are extensively utilized as orthopedic implant materials.However,issues like abrasion,inflammation,and adverse reactions can arise following implantation,potentially leading to implant dislodgment and even surgical failure in severe cases.In this work,by combining fiber laser,anodic oxidation and electrophoretic deposition methods,the micro-nano structure and coating composite structure are prepared on the surface of Ti6Al4V(TC4),and the coupling influence law of different composite structures on the implant performance is studied.The experimental results show that the prepared composite structures can effectively improve the wear and corrosion resistance and biocompatibility of implants.The specific research results are as follows.(1)Design and preparation of bionic micron structures.According to the study,the surface with hydrophilic properties promotes cell growth and biocompatibility of the implant.Based on the bionic principle,we designed the micron structure to improve the hydrophilicity of the surface by imitating the lip shape of pigweed which has super hydrophilicity.According to the design structure size requirements,the processing parameters were selected as follows:the primary structure requires 50 scans,processing speed of 10 mm/s,laser power of 100 W,and laser frequency of 50 kHz;the secondary structure requires 5 scans,processing speed of 400mm/s,laser power of 30 W,and laser frequency of 20 kHz.At this point,the microstructure surface morphology is complete,with a size similar to that of pigweed lips.The contact angle measurement is 32.4°,a significant 50.3° lower than that of the smooth surface,effectively boosting the implant surfaces hydrophilicity.(2)Surface nanostructure preparation process study.According to the contact induction theory,when the nanotube diameter is about 60 nm,it is closest to the size of cell adhesion spot and has the strongest effect on cell proliferation and differentiation.Titanium dioxide nanotubes were prepared by anodic oxidation,and the experimental results showed that the oxidation time of 1 h,the oxidation voltage of 30 V,and the diameter of the prepared nanotubes of about 60-70 nm were favorable to improve the biocompatibility.(3)Performance study of different combinations of micro and nano structures.Combining fiber laser and anodic oxidation methods to prepare micro-nanostructures,the ratios of micro-nano structures were regulated by changing the spacing of micron structures and their biocompatibility was investigated.Experimental results on the surface:as the ratio of micro-nano structures decreased,the contact angle decreased and then increased,and the apatite deposited on the sample surface increased and then decreased.When the ratio of the micro-nano combination was 1:3.5,the contact angle of the micro-nano structure measured 19.5°,which was 63.5°lower compared to the smooth surface,and the hydrophilicity was significantly increased,and the most bone-like apatite material was deposited on the surface after immersion in simulated body fluid,indicating the best biocompatibility.(4)Preparation of HA/CS coatings.The effect of different chitosan(CS)contents on the crystalline shape of hydroxyapatite(HA)coatings was investigated,and the wear and corrosion resistance of the coatings with different crystalline shapes was tested.Experimental results show that as the amount of CS increased,the crystalline shape of the coating exhibits spherical,needle-like and rod-like shapes,respectively.At a CS quantity of 0.5 g,the needle-shaped structure had finer grains.Compared to the smooth surface,the corrosion current density decreased by 1.1859 μA/cm2,the corrosion potential shifted positively by 0.3416 V,and the friction coefficient decreased by 0.1493,indicating the best resistance to corrosion and wear.(5)Study of the mutual coupling mechanism of composite structure on biocompatibility and wear and corrosion resistance.The simulated body fluid immersion method was used to test the biocompatibility of the composite structures.In the same soaking time,the results of the deposition weight gain ratio of different structures were:composite structure>coating>micro-nano structure>smooth surface,and the maximum weight gain ratio was 2.443%.When the micronano ratio was 1:3.5,the surface hydrophilicity and bioactivity after combining with the coating promoted each other and significantly enhanced the performance of composite structure-induced apatite deposition.Compared with the smooth surface,the corrosion current density of the composite structure is reduced by 1.1911 μA/cm2,the corrosion potential is positively shifted by 0.1313 V,and the friction coefficient is reduced by 0.3893,indicating that the composite structure effectively improved the wear and corrosion resistance.Abrasion and corrosion of the substrate is reduced because the nanostructure and coating act as a protective layer,blocking contact between the substrate and body fluids.In this thesis,we designed and prepared a composite structure combining a micro-nano structure and a coating.By combining the performance advantages of the micro-nano structure and the coating structure to improve the biocompatibility and wear and corrosion resistance of the implant surface,a new method is provided for the preparation of implants that function consistently and stably in vivo.