【作者】 陈晓明；

【导师】 李世普；

【作者基本信息】 武汉理工大学 ， 无机非金属材料， 2002， 博士

【摘要】 钛合金表面改性对于开发用于骨植入的医疗器械，如人工关节、牙根种植体、人工骨等有重要意义，是当今生物医学材料研究的前沿课题之一。本文从改善钛合金表面钙磷生物涂层的稳定性入手，采用化学处理、高温真空镀钛和电泳共沉积（EPCD）——烧结等技术对钛合金的表面进行了改性的研究，通过对涂层的结构和组成的梯度设计和EPCD——烧结技术的研究，获得了较系统的能在复杂形状的制品表面涂覆钙磷梯度涂层及其低温快速烧结技术，并研制出了高性能的钛合金／生物玻璃（BG）／羟基磷灰石（HA）梯度涂层。该技术为低成本、无污染的环境友好技术，并有希望扩大钙磷生物医学涂层的应用领域，提高其使用寿命。 分别用酸和碱（硝酸和氢氧化钠）对钛合金表面进行处理，用等离子发射光谱测定腐蚀产物的成分，用SEM观察钛合金表面形貌，结果发现硝酸使钛合金表面发生均匀性腐蚀，因此不能选择性的溶出钛合金表面的V和Al元素；氢氧化钠能选择性溶出钛合金表面的V和Al元素，而让Ti元素以凝胶态的TiO₂形式留在钛合金表面，该凝胶态的TiO₂不仅有良好的生物相容性，可诱导钙磷矿物沉积，而且还有利于与生物玻璃的烧结结合。因此，预计该碱处理方法是一种良好的钛合金表面生物涂层的前处理方法。 为了探讨在钛合金表面镀一层纯钛以改善钛合金表面的生物相容性的可能性，开展了钛合金表面高温真空镀钛的研究，用扫描电子显微镜（SEM）和电子探针X-射线荧光微区分析（EPMA）研究钛合金表面和断面元素含量的分布及变化，结果发现，Ti6Al4V合金在1000℃下过饱和Ti蒸气环境中进行2～4小时的蒸镀，表面会形成厚度约20μm且富含V元素的金属Ti镀层。蒸镀过程中，合金内部的晶粒会急剧长大，Ti6Al4V合金中的V元素存在着表面偏析现象，Al元素存在由浓度差引起的扩散运动。将Ti6Al4V合金在1000℃下进行真空热处理会降低其力学性能，且合金内的V元素会向表面富集，因此，钛合金真空热处理和表面涂层的烧结温度不能过高，即应低于其相转变点； 通过对生物活性梯度涂层的组成和结构的设计，分析和计算了梯度涂层内的应力大小和分布，结果表明：对于本研究，当成分分布系数n=1.5时，可以获得较合理的涂层力学性能，即在沉积开始时，采用富含BG颗粒的悬浮液，以便在钛合金侧获得同iCtgM’eMx＊＆CZ M f底层BG有良好过渡的富BG涂层；梯度涂层界面和表面的应力大小、性质（压应力或张应力）由材料组成本身的性质决定，改变成分分布系数，只能改变涂层内应力变化的趋势；涂层的厚薄不影响涂层内的应力分布规律，但涂层越薄，涂层内的应力变化越快，但这并不意味着涂层越厚越好，因为涂层越厚，涂层允许的变形越小，对于应用于弯曲受力部位的涂层而言，涂层应薄一点为好（50 u m）；而对于仅纯受剪切应力的部位，如牙根种植体，涂层可适当加厚（80100 u m）； 通过对HA和BG颗粒在水溶液体系和非水溶液体系中的带电特性和电泳沉积 （EPD）的研究发现，它们在水溶液体系中很难发生电沉积；在无水乙醇溶液中，HA颗粒带正电，可在阴极钛合金片上发生均匀的电泳沉积，而BG颗粒则带负电荷；利用复分解反应法，可以制得100－300urn的HA，通过诱导HA在BG颗粒表面结晶，可对BG颗粒进行表面包覆，获得了被HA包覆的SG颗粒，改变了BG颗粒表面的带电特性，使 BG和 HA颗粒在无水乙醇中均带上正电荷，从而实现了 HA和 BG颗粒在阴极上的共沉积。因此，利用EPCD来制各BGIHA梯度涂层是可行的。 通过对高硼生物玻璃（8’）涂层和等离子喷涂涂层作腐蚀实验研究发现：高硼生物玻璃在制备过程中出现了分相，即分为富硅相和富硼相，在碱性环境中其腐蚀行为表现为均匀腐蚀，腐蚀主要发生在富硼相区，因此，BG配方的设计应尽量避兔玻璃分相的发生；等离子喷涂涂层的腐蚀表现出非均匀腐蚀，腐蚀主要发生在熔滴叠层的边缘，且腐蚀有加速趋势，易引起贯通至涂层界面的腐蚀裂纹，从而引起界面渗透腐蚀，这可能是等离子喷涂涂层后期脱落的主要原因之一。通过对生物玻璃和钛合金热膨胀系数的测试，表明2’生物玻璃与钛合金在热膨胀系数上更匹配，能与钛合金在较低的温度（720C）烧结成致密釉层。生物相容性评价试验结果表明，高硼生物玻璃（8‘）仍具有良好的生物相容性： 通过对BG和HA颗粒在乙醇溶液中的EPCD及其烧结工艺的研究，结果表明：通过连续改变电泳溶液中分散颗粒BG和HA的浓度比例，采用脉冲直流电源（频率为1200Hi，占空比为 114），可以在钛合金表面制备出 BG／HA梯度涂层；当 HA和 BG的粉浆浓度均为30g／L，两电极间距为1．scm时，较优的沉积工艺为：沉积电压为30V，沉积时间个枷1＊s：低的沉积电压下倾向于获得致密涂层，而在高的沉积电压下则倾向于获得疏松多孔的涂层，通过提高沉积电压，可以控制涂层的气孔率，从而制备具有气孔结构梯度的涂层；钛合金／BG／HA梯度涂层烧结的较优工艺为大气低温快速烧结工艺，其工艺参数为：升温速度为50’C／min，烧结温度720t，保温时间7 mins，自然AZedryX－we－－x－＆Ik f冷却；涂层最大更多还原

【Abstract】 It is very important to improve the surface characteristics of titanium alloy (Ti6A14V) for developing medical treatment appliance as artificial bone, such as artificial joints* artificial root of tooth and artificial bone, etc. The related research area is one of the front edges of biomedicine material research at present. In this thesis, the research about surface modification of titanium alloy was carried on starting with improving stability of calcium phosphate biomedical coating by force of chemical treatment, Physical Vapor Deposition(PVD) of titanium metal at high temperature and Electrophoresis Codeposition(EPCD) and sintering technology of the coating. By way of the studying of graded design of microstructure and composition of coating and EPCD and sintering technology, a systemic technology by which a calcium phosphate graded ceramic coating was prepared and sintered rapidly on the surface of a complex shaped product was obtained and a high function titanium alloy/bioglass(BG)/hydroxyapatite(HA)graded coating was developed. The technology is low costing, no pollution and friendly to environment, which will extend the application area of calcium phosphate biomedical coating and lengthen its life span of usage.Treat the surface of titanium alloy with acid and base, nitric acid and sodium hydroxide respectively, measure composition of the corrode products using Plasma Emission Spectrum and observe surface morphology of the corroded titanium alloy with SEM, the results showed that a homogenization corrosion occurred while nitric acid was used, so a selective dissolution for element V and Al on the surface of titanium alloy could not be achieved, but sodium hydroxide could do and leave Ti element in gel state TiO^ on the surface of titanium alloy. The gel TiO2 not only has good biocompatibility, but also can induce deposition of calcium phosphate minerals and is beneficial to the banding of biogas with the titanium ally surface, so the base processing method is expected to be a good pretreatment method of titanium alloy surface for biomedical coating.In order to improve biocompatibility of titanium alloy surface the PVD of pure metal Tion the titanium alloy surface in vacuum and at high temperature was studied. After the PVD the variation of elements content and distribution on the surface and cross section of titanium alloy were analyzed using Scanning Electron Microscope (SEM) and Electron Probe X-ray Fluorescence Micro area AnalysisC EPMA), the results showed that a Ti coating in thickness of 20 u m, containing richly element V, formed on T16A14V alloy surface after the evaporating and condensing at 1000癈for 2~4 hours, and grains in the alloy could grew up rapidly during the heat treatment, which will cut down mechanics behavior of the titanium alloy, and a segregation phenomenon of element V near the titanium alloy surface occurred. For element Al there only existed diffusing transfer causing by concentration difference. Therefore, the heat treatment of T16A14V alloy should be carried out at lower temperature that is under its phase shift point.Through designing of composition and structure of the bioactive graded coating, innerstress and its distribution in the coating were analyzed and calculated, the results showed that when composition distribution coefficient n was 1.5, a reasonable stress distribution could be got, that was at the beginning of deposition the suspension containing richly BG granules was used so that a rich BG granules layer, a good transitional layer between BG layer at the bottom and the coating could be obtained at the titanium alloy side, the bottom of the coating; the stress value near the interface and surface and its character, pressure stress or tensile stress, were decided by the character of its composition itself. Changing composition distribution coefficient n could only change the variation tendency of stress in the coating, but did not change the stress distribution rule in the coating. The thinner the coating is, the sharper stress variation in the coa更多还原