【作者】 张琦；

【导师】 汤玉斐；

【作者基本信息】 西安理工大学 ， 材料学， 2021， 硕士

【摘要】 定向层状多孔钛支架具有各向异性的孔结构,因此单一方向上的力学强度更高,在骨植入承重材料中应用前景广阔。当多孔钛承受压缩载荷时,孔壁会发生屈曲变形、层间弱结合导致层间发生劈裂,因此提高孔壁强度和层间稳定性是提高支架力学性能的关键。本文采用定向冷冻干燥法结合TiH₂原位还原反应,制备了具有定向直通孔结构的多孔钛支架。通过在孔壁中引入石墨烯片原位反应生成TiC,对孔壁进行强化。此外,在层间引入碳纤维形成桥接结构,对孔壁约束提高其层间稳定性。对碳化物增强定向直通多孔钛支架的物相组成、孔结构、增强相与基体界面进行了研究,并表征了其力学性能和生物相容性。引入石墨烯片后多孔钛支架仍呈层状多孔结构,其孔尺寸和孔隙率降低,石墨烯片与孔壁中的Ti原位反应生成碳化钛,在孔壁中与基体界面结合良好。原位反应生成的TiC作为第二相强化了多孔钛的压缩强度,最高达389.94MPa,是未强化支架的3.78倍,同时其弹性模量仅为8.2GPa,与人骨模量相匹配,且碳化钛原位增强多孔钛支架具有良好的生物相容性。引入碳纤维后,部分碳纤维进入孔壁并发生原位反应生成TiC,部分碳纤维形成层间桥接结构,层间桥接的碳纤维经过纤维表面钛原子与碳原子的相互扩散,原位反应生成TiC/Ti纤维,其两端与基体结合紧固,可以有效减缓层间劈裂。随着碳纤维的含量增加纤维桥接密度增大,纤维桥接多孔钛支架压缩强度最高达161.66MPa,相对于纯钛支架提高了58.24MPa,而弹性模量仅为5.99GPa。同时,该支架还具有低的生物毒性和良好的生物相容性,作为骨植入材料有良好的应用前景。更多还原

【Abstract】 Because of the anisotropic pore structure,the directional layered porous titanium scaffolds have higher mechanical strength in a single direction,which has a broad application prospect in bone implant load-bearing materials.When porous titanium is subjected to compression load,the pore wall will be buckling deformation,and the weak interlaminar bonding will lead to interlaminar splitting.Therefore,improving the pore wall strength and interlaminar stability is the key to improve the mechanical properties of the scaffold.In this paper,porous titanium scaffolds with directional straight through structure were prepared by directional freeze-drying combined with in-situ reduction reaction of TiH₂.The pore wall was strengthened by in-situ reaction of TiC by introducing graphene sheets into the pore wall.In addition,carbon fiber is introduced into the interlayer to form a bridging structure,which can constrain the pore wall to improve the interlayer stability.The phase composition,pore structure and the interface between the reinforcement phase and matrix of the porous titanium scaffold reinforced with carbide were studied.After the introduction of graphene sheets,the porous titanium scaffold still shows layered porous structure,and the pore size and porosity decrease.The graphene sheets react with the Ti in the pore wall in situ to form titanium carbide,which is well bonded with the matrix interface in the pore wall.TiC generated by in-situ reaction as the second phase strengthened the compressive strength of porous titanium,up to 389.94MPa,which was 3.78 times that of the unstrengthened scaffold.Meanwhile,its elastic modulus was only 8.2GPa,which matched with the modulus of human bone.Moreover,the in-situ reinforced porous titanium scaffold had good biocompatibility.After the introduction of carbon fibers,some of the carbon fibers enter the pore wall and react in situ to form TiC,and some of the carbon fibers form interlamellar bridges.The interlamellar bridges of the carbon fibers through the diffusion of titanium atoms and carbon atoms on the surface of the fibers generate TiC/Ti fibers by in-situ reaction.The two ends of the carbon fibers are tightly bound with the matrix,which can effectively reduce the interlamellar splitting.With the increase of carbon fiber content,the fiber bridging density increases,and the compressive strength of the porous titanium scaffold is up to 161.66MPa,which is increased by 58.24MPa compared with the pure titanium scaffold,while the elastic modulus is only 5.99GPa.At the same time,the scaffold has low biotoxicity and good biocompatibility,so it has a good application prospect as bone implant material.更多还原