【作者】 焦玉恒；

【导师】 陈晓明；

【作者基本信息】 武汉理工大学 ， 材料学， 2004， 硕士

【摘要】 用于替换承受较大载荷的人体硬组织的植入材料，不仅应具有良好的骨结合能力，还应具有高的强度和韧性。但目前的生物活性陶瓷和具有一定生物相容性的金属都不能同时满足这些要求。陶瓷的断裂韧性远低于人的皮质骨，且至今也没有一种金属材料能够与人体骨直接结合。在金属表面涂覆生物活性涂层，可兼顾生物活性陶瓷的骨结合能力与金属材料良好的力学性能。本文从涂层的结构设计出发，探索了一种在钛合金表面制备高稳定性生物活性涂层的新工艺。采用电泳沉积工艺，在非线性形状金属表面成功制备出了羟基磷灰石（HA）—生物玻璃（BG）复合涂层。HA-BG复合涂层底层为致密玻璃层，与钛合金基体紧密结合并防止了体液渗入涂层与金属界面。外层为疏松的HA-BG复合层，能够提供与人体硬组织良好结合的条件。 本文采用的生物玻璃是以Na₂O-CaO-SiO₂-P₂O₅生物玻璃体系为基础，结合在钛合金表面制备涂层的要求设计的Na₂O-CaO-SiO₂-P₂O₅-B₂O₃-TiO₂-CaF₂系BG。该BG的热膨胀系数在＞320℃时稍大于钛合金Ti6Al4V的热膨胀系数，＜320℃时稍小于Ti6Al4V的热膨胀系数；熔化温度较低（＜700℃）；与基体结合强度高且稳定。电泳沉积工艺采用乙醇体系，BG与HA粉料能够用乙醇制得较稳定悬浮体系。采用离子吸附的方法，反转了BG颗粒在乙醇中的荷电性质，使其与HA颗粒带同种电荷，从而实现了二者的电泳共沉积。本文分别研究了离子浓度、沉积电压、沉积时间和悬浮液固体含量对HA和BG电泳沉积的影响，优化了此体系电泳沉积的工艺参数。采用两步电泳沉积法，先后在钛合金表面沉积BG层和HA-BG复合层。热处理制度采用低温快烧法。 采用粘结拉伸法测定涂层与基体的结合强度，研究了玻璃涂层结合强度与热处理制度的关系和复合涂层结合强度与HA含量的关系，BG涂层结合强度可达35MPa以上，复合涂层结合强度可达25MPa以上。通过测定浸泡玻璃前后溶液离子浓度的变化及不同离子的对比实验，证明了BG颗粒对Ca²⁺的选择性吸附及其对BGξ-电位的影响。采用SEM，EPMA，EDXA等测试方法，分析了涂层的结构与元素分布情况，证明了涂层具有底层致密，表层疏松的结构。HA颗粒镶嵌于玻璃熔体中，在涂层表层和涂层中孔洞内壁均有HA颗粒露出，增加了HA颗粒与体液的接触面积。实验表明乙醇体系电泳沉积工艺能够实现复杂形状金属表面复合涂层的制备;该涂层兼顾了其力学稳定性、化学稳定性及生物活性，能够解决当前生物涂层稳定性低的问题。更多还原

【Abstract】 Implant materials to be used as substitutes for high load-bearing bones need to possess not only bone-bonding ability but also high fracture toughness. However, neither the currently available bioactive ceramics nor biocompatible metals fulfill both these requirements. The fracture toughness of ceramics are lower than that of human cortical bone, and none of biometals can directly bonds to living bone. Coating bioactive ceramics onto a tough biometals integrates the bone-bonding ability of bioactive ceramics and the mechanical properties of the biometals. So, in this paper, we developed a new technology to prepare highly stable bioactive coating on titanium alloy. The technology of preparing Hydroxyapatite (HA) - Bioglass (BG) compound coating on a non-line-sight titanium alloy substrate was realized by electrophoretic deposition (EPD). The dense glass layer, as the inner sublayer of the compound coating, which could bond with the substrate by chemical bonding and mechanical locking, prevents the body fluid seeping into the interface between the coating and substrate. The outmost sublayer is porous HA-BG compound layer which can provide an excellent environment for bonding with a living bone.According to the requirements of coating on T16A14V alloy, the bioglass used in this experiment was designed on the basis of the Na2O-CaO-SiO2-P2O5 bioglass system. The composites of the bioglass are listed as below: Na2O-10. CaO-15, SiO248, P2O5-5, B2O3-10, TiO2-6, CaF2-6 (wt%). The thermal expansion coefficient of the bioglass is slightly higher than that of Ti6A14V alloy at high temperature (>320℃) and slightly lower at low temperature (<320℃). The melting temperature of the bioglass is lower than 700℃. Therefore, the bioglass has high chemical stability and can bond with the substrate after thermal treatment. The preparation process of EPD was carried on in the ethanol system, and the suspensions of BG and HA is stable in this system. Furthermore, the charge of BG particle was reversed through ion absorption, which made both BG and HA charged positively and realized the co-deposition of them in ethanol. The effect of concentration of ions, depositionvoltage, deposition time and solid concentration of the suspension to the EPD was also studied in this paper. Through two-step electrophoretic deposition, a BG layer and a HA-BG compound layer were successively deposited on the titanium alloy substrate. The thermal treatment of the coating employed the low-temperature-fast-firing technology.The relationship between the bonding strength of the BG coating and the thermal treatment system and that between the bonding strength of the compound coating and the amount of HA were studied in this paper. It is shown that the bonding strength of the BG coating was higher then 35 MPa. and that of the compound coating was higher then 25 MPa. The concentration of Ca2+ in ethanol solution before and after the BG was immersed by the solution was tested and the control experiment with other ions was carried out. The results presented that Ca + was absorbed onto the BG particles selectively and changed the zeta potential of BG in ethanol. The microstructure and the element distribution of the coating were analyzed by Scanning Electron Microscope (SEM), Electron Probe Micro-Analysis (EPMA) and Energy Dispersion X-ray fluorescence analysis (EDXA). The results revealed the structure of inner dense sub-layer and outmost porous sub-layer. The HA particles embedded in the bioglass could be seen from both the surface of the coating and the wall of the inner pore of the coating, which enlarged the contact area of the HA with the body fluid. The results showed that the HA-BG compound coating could be prepared by EPD in ethanol system. Integrating the mechanical, chemical stability and the bioactivity, the coating could resolve the problem of low stability in the current Ca-P bioactive coatings.更多还原