中文论文文摘

    碳/碳（C/C）复合材料是国际新材料领域重点发展的一种新型材料，兼具功能和结构特性，综合性能优异，作为骨修复和骨替换材料，极具应用前景。但它为生物惰性，为了发挥它的力学性能，同时又使它能够引导或诱导骨组织形成，可在其表面制备生物活性涂层。本文在综述钛基金属和碳基复合材料表面生物活性改性研究进展的基础上，对C/C复合材料表面制备生物活性羟基磷灰石（HAp）涂层进行了研究，主要研究内容如下。
    借助水热反应在溶液中产生的高温、高压的超临界特性，提出了一种在C/C复合材料表面制备HAp涂层的新工艺-水热电沉积。通过该方法，在C/C复合材料表面制备了HAp涂层，重点研究了Ca2+浓度、Ca/P原子摩尔比、电解液pH值、温度、电流密度、电压对HAp涂层晶相组成、形貌、结构、沉积量的影响规律；其次，为了提高涂层的性能，在沉积溶液中加入乙醇，重点研究了乙醇的添加量对提高涂层结合强度的影响。
采用X射线衍射（XRD）、扫描电镜（SEM）等分析手段对HAp涂层组成、形貌及结构进行了表征；通过测量样品沉积前后的质量，来表征HAp 的沉积量；涂层的结合强度通过万能材料试验机进行表征。
    研究结果表明：水热电沉积方法制备C/C复合材料表面HAp涂层，最佳的Ca2+浓度、Ca/P原子摩尔比、电解液pH值分别为0.02 mol/L、1.67和4.8。在水热温度为100~140℃范围内，都可以在C/C复合材料表面制备出HAp涂层，随着水热温度的升高，涂层的结晶性能变好，涂层的致密性和均匀性明显提高，且涂层与基体的结合强度增加，HAp晶体还表现出一定的沿（210）和（211）晶面取向生长的特征。随着沉积时间的延长，涂层的结晶性能变好，涂层表面结构变得更加致密和均匀。电流密度对涂层性能影响的研究结果表明：随着沉积电流的升高，涂层结晶性能明显变好，涂层变得更加致密和均匀，且HAp晶体表现出一定程度的沿 (211) 晶面取向生长的特征。且随着电流密度的增加，HAp的沉积速率是呈线性增加的。采用恒电压法沉积HAp涂层时，在电压为3~10 V范围内可以在C/C表面制备出HAp涂层。随着电压的升高，涂层的结晶性能变好，涂层的致密性和均匀有了明显的提高，且涂层与基体的结合强度增加，HAp表现出一定程度的沿 (211) 晶面取向生长的特征。此外随着沉积电压的升高，HAp的沉积量增加。
    在沉积溶液中添加乙醇对HAp涂层性能有明显的影响。结果表明，在乙醇添加量从0~20%变化范围内，随着乙醇的增加，涂层的结晶性能没有明显的变化，涂层的组成由针状晶粒和少许小的颗粒状晶粒共同组成的结构变为由单一的针状晶粒组成的，且涂层的致密性和均匀有了明显的提高，HAp晶粒有垂直于基体表面生长的趋势。此外，涂层与基体的结合强度也有了大幅度的提高。
    对水热电沉积制备HAp涂层工艺过程进行了简化，提出了相应的物理模型。根据简化的水热电沉积HAp涂层物理模型，给出了沉积过程中受扩散过程控制的动力学方程，设计了相应的实验，证实水热电沉积HAp涂层时，沉积速率主要受溶液中的离子向阴极表面的扩散速率所控制。同时， HAp涂层沉积动力学研究表明，随温度升高，涂层的沉积量增加；水热电沉积HAp涂层所需的活化能为25.8 kJ/mol。

外文论文文摘

    Carbon/carbon (C/C) composite is a novel material developed in the new material field and has great prospect in bone repair field due to excellent mechanical properties, especially elastic modulus close to that of human bones. However, C/C composite is bionert, in order to endow it with osteoconductivity and osteoinductity, biomedical materials with bioactivity could be coated on it. In this paper, on the basis of the reviews on two respects: titanium-based bioactive modification and bone tissue response to carbon materials, the research work would be focused on new preparation technologies, mechanism and bone response behaviors in vitro and in vivo of hydroxyapatite (HAp) coating deposited on C/C composite, the main contents were as followings.
    Due to the super critical effect of the hydrothermal reaction, a novel method –hydrothermal electrodeposition for preparing HAp coating on C/C composites was put forward. The HAp coatings were successfully prepared on C/C composites by this method. The influences of [Ca2+] concentrations, Ca/P in molar ratio, pH value, hydrothermal temperature, deposition time, current density, deposition voltage on the microstructures and morphologies of HAp coatings were investigated; and the effect of ethanol to the coating adhesion strength was also particularly investigated.
    The as-prepared HAp coatings were characterised by X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. The coating deposition amount was measured, and the adhesion strength between the coating and the substrate was surveyed by universal testing machine.
    The results show that the optimal values of [Ca2+] concentrations, Ca/P in molar ratio and pH should be 0.02 mol/L, 1.67, and 4.8, respectively. The HAp coatings on C/C composites can be preparedat 100~140 ℃, and hydrothermal temperature has a big influence on the coatings phase composition, microstructure. Density and homogenous of the prepared HAp coatings are obviously improved with the increase of hydrothermal temperature. The adhesion strength between the coating and the substrate also has some extent improvement. In addition, the peak intensity of HAp along (210) and (211) directions increase with the increase of hydrothermal temperature, indicating the over growth of HAp crystallites along (210) and (211) directions. With the increase of deposition time, density and surface homogenous of the prepared HAp coatings are obviously improved. The influence of current density on the microstructure and morphology of hydroxyapatite coatings was also investigated. The crystallization, density and homogenous of the coatings are improved with the increase of current density, and HAp crystallites are found growth along (211) directions in some extent. In addition, the HAp deposition rate increases linearly with the ncrease of current density. With the increases of deposition voltage, density, homogeneity, adhesion and deposition rate of the prepared HAp coatings are all markedly improved; and HAp crystallites are found growth along (211) directions in some extent.
To enhance the as-prepared coatings property, especially the adhesion strength, the ethanol was added into the solution. The ethanol content in the deposition solution has a big influence on the coatings microstructures and adhesion property with the substrate though has little effects on the coatings crystallization. With the increase of ethanol content from 0vol% to 20vol%, the density and adhesion property of the prepared HAp coatings are obviously improved.
    In order to comprehend the essence of the formation of HAp coating on carbon/carbon composite by hydrothermal electrodeposition, a simplified deposition model was put forward. In this model, the deposition procedure of HAp coating consisted of two steps: the first was the movement of ions containing P and Ca elements towards the C/C cathode by means of diffusion, and the second was the HAp coating growth on the C/C surface. The relevant mathematical model and the experiments to identify the physical and mathematical models were given. It was confirmed that the models were reasonable and the procedure of HAp coating formation by hydrothermal electrodeposition was mainly controlled by ion diffusion in the electrolyte. In addition, kinetics of HAp deposition on C/C composite were studied, the deposition kinetics of HAp coatings indicates that deposition amount and deposition rate increases with the increase of hydrothermal temperature; and the corresponding deposition activation energy of HAp coating by the hydrothermal electrodeposition process is calculated to be 25.8 kJ/mol.