冷喷涂制备多孔Ta涂层及生物相容性

Preparation and Biocompatibility of Porous Ta Coatings by Cold Spraying

目的提高生物医用钛合金的生物相容性。方法采用冷喷涂技术在其表面制备了内部多孔且表面粗糙的钽涂层,并对涂层的微观组织、弹性模量、表面粗糙度、孔隙率、相组成等进行表征;通过溶血率实验、动态凝血时间实验、血小板黏附实验和细胞增殖实验等评价其血液相容性。结果涂层表面粗糙度为24.9μm,孔隙率为12.6%,弹性模量为147 GPa。喷涂后涂层相组成为Ta,涂层与基体的结合强度为24 MPa。TC4钛合金基体和钽涂层2种材料均具有优异的红细胞相容性且2种材料表面的动态凝血程度相似,表明在TC4钛合金表面制备钽涂层后,钽涂层不会影响凝血因子的活性。钽涂层具有更好的防止血小板黏附与变形的性能。在细胞增殖实验中,细胞在钽涂层表面的增殖能力略高于TC4钛合金。结论多孔钽涂层的弹性模量相对钽块降低了22%。其生物活性高于TC4钛合金基体。

The work aims to improve the biocompatibility of biomedical titanium alloy.The porous Ta coating with a rough surface was prepared by cold spraying.The morphologies and microstructure of the powder and the coating were investigated by SEM.The phases of the coating were characterized by XRD and Raman.Besides,bonding strength of the coating was investigated by universal material testing machine.The elastic modulus of the coating was analyzed by nanoindentation experiment.The cellular compatibility of the coating was evaluated by hemolysis rate experiment,dynamic clotting time experiment,platelet adhesion experiment and cell proliferation experiment.The tantalum particles with different particle sizes were extruded and stacked with each other after plastic deformation.The surface roughness of the coating was 24.9μm and the rough surface structure of the tantalum coating increased the specific surface area of the material,creating favorable conditions for cell adhesion and subsequent proliferation.The porosity of the coating was 12.6%.The elastic modulus of tantalum block was 189 GPa,while the elastic modulus of porous tantalum coating was 147 GPa,a decrease of about 22%,which could to some extent reduce the"stress shielding effect"generated at the interface between the implant and bone,and increase the service life of the implant.The powder and coating were mainly composed of tantalum elemental phase,and no oxide phase of tantalum was observed,indicating that tantalum powder did not undergo oxidation during the cold spraying process.Tensile test results showed that the coating failure mode was coating/substrate interface failure and the bonding strength between the coating and the substrate was 24 MPa.The relative hemolysis rate of TC4 titanium alloy substrate and tantalum coating was less than 0.5%.This indicated that the two materials exhibited excellent red blood cell compatibility and no hemolysis in vitro experiments,meeting the international standard organization's requirement for a hemolysis rate of≤5%for medical materials.The dynamic clotting degree of TC4 titanium alloy and Ta coating was similar which indicated that the Ta coating on TC4 titanium alloy had no effect on the activity of coagulation factors.The results of platelet adhesion test showed that Ta coating had better performance of preventing platelet adhesion and deformation.It could be seen from the cell proliferation results that the number of surface cells of the two materials increased significantly with the extension of time,indicating that there was no short-term potential cytotoxicity of the two materials.Among them,the proliferation ability of cells on tantalum coating surface was slightly higher than that of TC4 titanium alloy.This was the result of the comprehensive effect of coating surface structure,coating characteristics,and activity factors.Therefore,it can be concluded that porous tantalum coating with rough surface is successfully prepared by cold spraying technology.The elastic modulus of porous Ta coating decreases by 22%compared to tantalum blocks and its biological activity is higher than that of TC4 titanium alloy matrix.