【作者】 邹鹑鸣；

【导师】 曾松岩； 张二林；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2008， 博士

【摘要】 多孔钛的孔结构可以诱导骨组织向内生长,增加界面结合强度、促进体液在其中流动、加快骨修复进程,因此在骨修复领域有广泛的应用前景。本文以钛丝为原料制备多孔钛,采用理论设计和计算的方法给出了多孔钛毛坯孔隙度的计算公式,分析了各参数对毛坯孔隙度的影响。优化了多孔钛的最终成形和真空烧结工艺。研究了多孔钛压缩性能及变形过程,给出了压缩屈服强度与孔隙度之间的理论关系式。以含硅羟基磷灰石(Si-HA)热力学与动力学几率分析为基础,在钛及多孔钛表面仿生制备了Si-HA涂层,最后对该涂层的生物活性进行了体外细胞试验和动物体内植入试验评价。得到如下结果:多孔钛毛坯孔隙度计算结果表明:调整钛丝直径dTi,最小螺旋直径D,以及螺旋升角θ1和θ2可以控制多孔钛毛坯的孔隙度。多孔钛成形研究表明:采用双向成形和循环加压可以获得孔尺寸更均匀的多孔钛。获得的医用多孔钛的孔隙为三维螺旋结构,其孔隙度的范围为53%-72%,孔隙尺寸范围为150-600微米,开孔率为90%-100%。压缩屈服强度为160-60MPa,杨氏弹性模量为5-2GPa。对多孔钛压缩过程的研究表明:孔隙度大于67%时,压缩过程分为三个阶段:弹性阶段、平台阶段和致密化阶段;孔隙度小于67%时,压缩过程只有弹性阶段和致密化阶段。对多孔钛孔隙度与压缩屈服强度间关系的研究发现:随孔隙度增加,压缩屈服强度降低。孔结构弹性坍塌和塑性坍塌对压缩屈服强度均有贡献。引入参数f衡量弹性坍塌对压缩屈服强度的贡献,试验结果表明f=0.15,说明弹性坍塌对压缩屈服强度有15%的贡献,塑性坍塌对压缩屈服强度的贡献为85%。研究了钛表面Ca(OH)2+NaOH混合碱-热处理工艺。结果表明通过混合碱处理在钛表面可引入Ca2+,处理后表面活化层呈网状多孔结构,物相主要为钙钛矿型CaTiO3和金红石型TiO2。同时研究发现表面含钙量、热处理温度和处理时间对表面活化层形态、物相及分布有影响。随着热处理温度和时间的增加,表面钛酸钙量增加,表面多孔结构被破坏,并且金红石逐渐变为短棒状。表面含钙量越高,钛酸钙越易于聚集成片且分布于表面。采用SBF体外浸泡实验研究了各个因素对表面生物活性的影响,结果表明:主要的影响因素为热处理温度,其范围为580-600℃;表面含钙量影响次之,应保持在0.87at.%附近。在此基础上,成功地将混合碱—热处理工艺应用于多孔钛表面处理,获得了内外均匀的表面活化层。热力学和动力学几率计算以及实验结果表明:当控制沉积液的pH值在7.0-8.0之间,SiO32-名义浓度小于5.0mM时,单相Si-HA优先生成。钛表面仿生制备的Si-HA涂层表面多孔,有珊瑚状凸起,涂层中的硅由内向外呈梯度分布;随着涂层平均含硅量增加,表面逐渐致密,涂层厚度减小。Si的引入增加了仿生Si-HA涂层与基体的剪切强度。将Si-HA涂层仿生制备工艺应用于多孔钛,获得了内外均匀的Si-HA涂层。体外细胞实验结果表明:Si的引入增加了Si-HA涂层的生物活性并加速细胞的矿化进程。培养初期,不同硅含量的表面粘附的细胞数量没有显著差异;7天后0.50wt.% Si-HA涂层表面粘附的细胞明显多于其它硅含量的涂层(p<0.05),这表明0.50wt.% Si- HA表现出更好的生物相容性。动物体内植入试验表明:Si-HA涂层可以诱导新骨沿涂层向骨髓腔内生长和向外生长(向肌肉方向),并且新骨与涂层的界面结合紧密,验证了Si-HA涂层具有良好的骨诱导性。更多还原

【Abstract】 Porous titanium can induce bone to ingrow into porous structure, which enhances the interface intensity. Body fluid can flow in connected pores, which accelerates the course of bone healing and remodelling. Therefore, porous titanium shows great potential for the bone implant application. Titanium wire was used as material to sinter porous titanium in present dissertation. An equation to design and predict the porosity of porous titanium preform was given by means of theoretical design and calculation, and the effect factors on the porosity of porous titanium preform were analyzed. The final forming and vacuum sintering process was studied. The compressive deformation process and compressive properties were studied, and the relationship between porosity and compressive yield strength was given. On the base of thermodynamics and dynamics analysis, the silicon-containing hydroxyapatite (Si-HA) was prepared on titanium by a biomimetic method. The bioactivity of Si-HA coating was assessed through in vitro cell experiment and in vivo implantation experiment. The results are summaried as follows:The calculated results of the porosity of the porous titanium preform showed that the porosity could be controlled by changing the diameter of the titanium wire (dTi), minimum screw diameter (D) and helix angles (θ1 andθ2).The results of the forming of porous titanium showed that the two-direction-shaping method and the cyclic pressure method made the pore uniform. The obtained biomedical porous titanium had a 3-dimemsion and helix pore structure. The range of porosity was 53%-72%, the range of pore size was 150-600μm, and the range of open-cell percent was 90%-100%. The compressive yield strength ranged 160-60MPa, and Young’s modulus was 5-2GPa.The compressive deformation process was studied. The result showed that when the porosity is larger than 67%, the compressive process includes three stages: elastic stage, plateau stage and densification stage. When the porosity is less than 67%, the compressive process includes two stages: elastic stage and densification stage.The relationship between the porosity and the compressive yield strength was studied. The result showed that the compressive yield strength was reduced with the increasing of the porosity. The elastic collapse and the plastic collapse of pore structure were contributed to the compressive yield strength. f was introduced to assess the contribution of the elastic collapse in the stage of yielding. The experimental results showed that the value of f was 0.15, which indicated that the percent of the elastic collapse contributed to the compressive yield strength was 15%, and the percent of the plastic collapse contributed to the compressive yield strength was 85%.The process of mixed alkali (Ca(OH)2 + NaOH) and heat treatment of the titanium surface was studied. Ca2+ was introduced into the surface and the active layer of the surface had a network porous structure after mixed alkali treatment. The phases on the surface were CaTiO3 and rutile mainly. Surface Ca content, the temperature and the time of the heat treatment affected the morphology, the phases constitute and the distribution of the active layer. With the increasing of the temperature and time of heat treatment, the amount of CaTiO3 increased, the network porous structure of the surface was broken, and the shape of rutile changed into a cosh. The more the surface Ca content had, the more CaTiO3 congregated in a flake shape on the surface.The bioactivity of the surface layer was assessed by immersing it in a simulated body fluid (SBF). Influential factors for the bioactivity were the temperature of the treatment temperature, which should be within a range of 580-600℃, and the surface Ca content, which should be at 0.87 at.%. The optimal process of the mixed alkali and heat treatment was applied to porous titanium, and the active layer was uniform all over the porous titanium.The calculated result of thermodynamics and dynamics probability analysis of Si-HA and the experimental result showed that the single phase of Si-HA could be obtained preferentially on the condition of the range of pH value being 7.0-8.0 and the nominal concentration of SiO32- in the immersion solution being less than 5mM. A Si-HA coating was prepared on titanium by a biomimetic method. The surface of the Si-HA coating was porous, and there was coralloid gibbosity on the surface. Si concentration was descent in Si-HA coating from outside to inside. When the Si content increased, the coating became denser and thinner. The introduction of Si in the coating could enhance the shearing strength. The biomimetic method was applied to porous titanium, and the Si-HA coating was uniform all over the porous titanium.The in vitro cell experimental result showed the introduction of Si could enhance the bioactivity and accelerate the biomineralization. The amount of Si content did not show distinct difference in cell attachment on the coating in the early culture stage. After 5 days culture,the most cells were observed on the Si-HA coating with 0.50 wt.% Si, indicating that the surface has the best bioactivity.The in vivo implantation experimental result showed that the Si-HA coating could induce the ingrowth of new bone into porous titanium toward the directions of marrow cavity and muscle. The new bone was well integrated with the Si-HA coating, which testified the better osteoinduction of the Si-HA coating.更多还原