【作者】 王志强；

【导师】 吕秉玲；

【作者基本信息】 大连理工大学 ， 化学工艺， 2008， 博士

【摘要】 氧化铝陶瓷和羟基磷灰石（Hydroxyapatite,简称HA或HAP）陶瓷是研究和应用最广泛的两种生物陶瓷材料。这两种材料都具有各自的优缺点,但作为生物材料它们的性能具有互补性,采用一定的技术将二者复合在一起可以制备出高强度的生物活性陶瓷材料。由于烧结特性和热膨胀系数等性能的差异,将二者直接复合或在氧化铝陶瓷表面制备HA薄膜所获得的结果并不理想。如能借鉴梯度功能材料的设计思想,在α-Al₂O₃陶瓷基体表面制备组成呈梯度变化的HA—玻璃涂层,便可以有效地降低涂层和基体间的热应力,得到结合牢固的HA—玻璃—α-Al₂O₃梯度复合生物陶瓷材料。这种材料兼顾了HA陶瓷和α-Al₂O₃陶瓷的优点,具有很大的研究和应用价值。因此本文对HA—玻璃—α-Al₂O₃复合生物材料及梯度复合生物活性材料的制备、结构、性能与应用进行了基础研究。具体工作和所获的成果如下:1.用湿法在水—无水乙醇体系下合成了粒度30～50nm的羟基磷灰石（HA）粉。研究了凝胶洗涤和干燥方式等因素对粉体粒度等特性的影响,确定了合成纳米羟基磷灰石粉体的最佳工艺条件。对纳米HA和煅烧粗化的HA粉体的烧结特性进行了研究和对比。用常压烧结法分别制备了CaO-P₂O₅-SiO₂玻璃、R₂O-Al₂O₃-B₂O₃-SiO₂玻璃、α-Al₂O₃和R₂O-Al₂O₃-B₂O₃-SiO₂玻璃—α-Al₂O₃增韧HA生物陶瓷材料。通过测试坯体烧结收缩率、抗弯强度和断裂韧性(K_IC)等性能研究了坯体组成对陶瓷材料的烧结特性和机械强度的影响;利用DTA、XRD、IR等手段分析了材料在烧结过程中所发生的物相变化,并用SEM观察了不同条件下制备的陶瓷材料的显微结构。上述工作为进一步设计和制备HA—玻璃—α-Al₂O₃梯度复合生物材料提供理论基础和实验依据。结果表明:CaO-P₂O₅-SiO₂玻璃能促进HA的烧结,并具有一定的增强作用;R₂O-B₂O₃-Al₂O₃-SiO₂系统玻璃可以显著降低HA烧结温度,但会促进HA的分解:适量α-Al₂O₃在HA陶瓷中具有增强作用,但过多的α-Al₂O₃会阻碍HA的烧结使烧结温度提高,烧结温度提高会导致HA分解转变成TCP。同时使用超细α-Al₂O₃和R₂O-B₂O₃-Al₂O₃-SiO₂玻璃复合增韧HA陶瓷可以取得较好效果。在复合陶瓷材料中玻璃起到降低烧结温度,促进烧结的作用;超细α-Al₂O₃起到增韧补强的作用,同时也能在一定程度上阻碍烧结过程中玻璃与HA的相互作用,防止HA分解。当α-Al₂O₃含量为10%（wt）,玻璃含量为20%（wt）时,在1200℃下烧结1h可以获得平均抗折强度为105.82Mpa,平均K_IC值为0.84 MPa·m^1/2的复合HA生物陶瓷。2.以低温燃烧法合成的α-Al₂O₃超细粉体为主要原料、CaO-MgO-Al₂O₃-SiO₂玻璃为熔剂,采用常压烧结法制备了α-Al₂O₃陶瓷基体。在α-Al₂O₃陶瓷表面制备了HA—玻璃—α-Al₂O₃梯度复合生物涂层。其中玻璃分别采用了CaO-P₂O₅-SiO₂玻璃和R₂O-Al₂O₃-B₂O₃-SiO₂玻璃。研究了梯度涂层组成和结构对涂层与α-Al₂O₃陶瓷基体结合牢度和整体梯度材料抗折强度的影响;利用SEM观察了涂层断面和表面的显微结构,并用EDS分析了涂层断面的化学组成变化。对HA—玻璃—α-Al₂O₃梯度生物涂层的研究结果表明R₂O-Al₂O₃-B₂O₃-SiO₂玻璃比CaO-P₂O₅-SiO₂玻璃更适合于制备梯度复合材料。当采用R₂O-Al₂O₃-B₂O₃-SiO₂玻璃为梯度涂层玻璃组成,并在涂层中添加适量的超细α-Al₂O₃时,可以显著提高涂层的抗剥离强度。在适当的工艺条件下制备出了涂层与基体结合牢固,平均抗剥离强度达48.22MPa的α-Al₂O₃陶瓷基HA—玻璃—α-Al₂O₃梯度复合生物材料。3.对HA、HA—玻璃和HA—硅灰石（wollastonite,简记作W）—玻璃复合陶瓷的微波烧结进行了系统研究,确定了制备致密HA及其复合生物陶瓷材料的最佳微波烧结工艺条件。采用微波烧结制备高强度的ZrO₂-Al₂O₃陶瓷基体,并用微波烧结工艺在ZrO₂-Al₂O₃陶瓷基体表面制备了HA—硅灰石—玻璃梯度生物活性涂层。研究了烧结温度对涂层结构、相变和涂层与基体的结合牢度的影响,确定了最佳涂层烧结温度。微波烧结利于HA陶瓷坯体的致密化,可以实现低温快速烧结,并提高陶瓷的机械强度;微波烧结HA—玻璃复相陶瓷的效果不如纯HA,快速升温和烧结导致结构中多孔,强度较纯HA的低。微波烧结对HA的分解有促进作用,而且随着烧结温度升高和时间延长HA分解程度增大。微波烧结工艺可以用于制备梯度涂层材料,微波烧结所制备的HA—W—玻璃梯度涂层结构和性能与常规烧结法制备的梯度涂层相近。但利用微波可以实现快速烧结,缩短烧结周期,降低能耗。4.对HA—玻璃—α-Al₂O₃复合生物材料的生物医学性能进行了评价。在进行了一系列安全性评价试验基础上,采用物理模拟实验及小白鼠肌肉埋植实验研究了所研制的复合生物材料的降解特性;采用模拟体液（SBF）浸泡实验,用XRD、EDS和SEM等手段对HA—W—玻璃梯度涂层的生物活性进行了研究。生物医学性能评价结果表明:HA—R₂O-Al₂O₃-B₂O₃-SiO₂玻璃—α-Al₂O₃复合生物陶瓷材料对生物体无急性或亚急性毒性反应;溶血试验和热源反应试验结果表明,材料在生物体内不会引起溶血反应和热源反应;肌肉埋植试验结果表明,材料对肌肉无刺激性,发现有多核巨细胞吞噬现象,说明所研究的复合生物材料具有一定的生物降解现象。物理降解试验和肌肉埋植失重分析结果表明复合材料的组成对其降解特性有很大影响。HA—玻璃复合材料有一定的降解特性和良好的表面活性,而在复合生物材料中添加氧化铝有则利于提高耐久性。因此本文研制的HA—R₂O-Al₂O₃-B₂O₃-SiO₂玻璃—α-Al₂O₃梯度活性生物涂层具有表面活性高,内层耐久性好的优点,有利于临床应用。模拟体液浸泡实验表明,1150℃常规烧结和微波烧结的HA—W—玻璃梯度涂层都具有良好的表面生物活性,浸泡一段时间后表面形成了HA沉积层。而在1200℃下微波烧结HA—W—玻璃梯度涂层表面生物活性下降。更多还原

【Abstract】 α-Al₂O₃ and hydroxyapatite（HA or HAP） ceramics are two kinds of important biomaterials that have been widely studied and used for some time.They have some advantages and disadvantages,but their advantages are complementarity.To compose them by suitable process can prepare novel biomaterials with the both advantages ofα-Al₂O₃ arid HA ceramics,just as high sthrength and excerllent bioactivity.Because of the differences t between their sintering ability and thermal expansion coefficient,it can not get ideal results to compose them strightly or prepare HA coating on the surface ofα-Al₂O₃ ceramics.If the designing idea of gradient fimction materials（GFM） is used for reference,to prepare HA-glass gradient coating onα-Al₂O₃ ceramics,the residual thermal stress in the coating can be reduced effectively and HA-glass-α-Al₂O₃ gradient composite biomaterials with high bonding strength can be got.This kind gradient material has the both advantages of HA andα-Al₂O₃ ceramics and has high value to be studied and applied.In this dissertation,the praperation,structure,properties and apllying bases of HA—Glass—α-Al₂O₃ gradient composite biomaterials were studied.The main works are as following:1.Hydroxyapatite with a particle size 30-50nm was synthesized by wet route in water-alcohol solvent system.The influences of washing-filtrating and drying ways of gel on the particle characteristics of HA were studied.The sintering characteristics of nanometer HA and coarse HA which was fired and ground were researched preliminarily.The CaO-P₂O₅-SiO₂ glass,R₂O-Al₂O₃-B₂O₃-SiO₂ glass,ultrafineα-Al₂O₃,and R₂O-Al₂O₃-B₂O₃-SiO₂ glass—α-Al₂O₃ reinforced HA ceramics were prepared respectively by traditional sintering process.The influnces of the composition of ceramics body on the sintering character and mechanical strength were studied by the tests of bulk shrinkage of the body after sintered,bending strength and fracture toughness(K_IC).The phase transition or reactions between the compostions that taking place during sintering process was analyzed by DTA,XRD and IR,and the microstuctures of the ceramics prepared under diffrent conditions were observed by SEM.These works and results provided a fundamental and experimental basis for preparing HA—Glass—α-Al₂O₃ gradient composite biomaterials.The results show that CaO-P₂O₅-SiO₂ glass can accelerate the sintering of HA and has the reinforcement effect on HA ceramics;The R₂O-Al₂O₃-B₂O₃-SiO₂ glass can decrease the sintering temperature of HA,but it can urge the decomposition of HA when sintered at higher temperature;A suitable amount of ultrafineα-Al₂O₃ can reinforce the HA ceramics but it can block the sintering of HA and raise the sintering temperature when adding amount is more than 10%（wt）,the raising of sintering temperature can induce HA decomposing into TCP when it is sintered.The better result was got when R₂O-Al₂O₃-B₂O₃-SiO₂ glass andα-Al₂O₃ was used at same time to reinforce HA ceramics.Glass can accelerate the sintering of HA and lower the sintering temperature.Ultrafineα-Al₂O₃ has reinforcement effect and hinders the glass reacting with HA at some degree,and then prevents HA decomposing.When ultrafineα-Al₂O₃ addition amount is 10%（wt）,the glass addition amount is 20%（wt） and sintered at 1200℃,the HA-Glass-α-Al₂O₃ composite biomaterial with average bending strength 105.82Mpa and toughness K_IC 0.84MPa.m^1/2 can be got.2.α-Al₂O₃ cermics substrate was prepared by traditional sintering process when the ultrafineα-Al₂O₃ powder synthesized by low temperature combustion process used as main raw material and CaO-MgO-Al₂O₃-SiO₂ glass used as flux.The HA-Glass-α-Al₂O₃ gradient coatings were prepared onα-Al₂O₃ substrate.Two kinds of glass were used as the compositions of the coatings,i.e.CaO-P₂O₅-SiO₂ glass,R₂O-Al₂O₃-B₂O₃-SiO₂ glass.The influences of the composition and structure of the gradient coating on the combination intensity between the coating and ceramic substrate and the bending strength of the whole gradient composite were studied.The microstructures of surface and cross section of the gradient coating were observed by SEM,and the variation of chemical composition along the cross section was analyzed by EDS.The researching results of HA-Glass-α-Al₂O₃ gradient coating show that R₂O-Al₂O₃-B₂O₃-SiO₂ glass is more suitable to be used as the compenent of gradient coating than CaO-P₂O₅-SiO₂ glass.When R₂O-Al₂O₃-B₂O₃-SiO₂ glass is used and suitable amount ultrafineα-Al₂O₃ is added in the coating,the combination intensity between the coating and ceramic substrate increases remarkably.The HA-Glass-α-Al₂O₃ gradient composite biomaterials in which the coating combining withα-Al₂O₃ ceramic substrate tightly,the average combination intensity is about 48.22Mpa,can be prepared under a suitable condition.3.Microwave sintering of HA,HA-Glass and HA-Wollastonite（W）—Glass composite ceramics was studied systematically.The best process of microwave sintering of dense HA and these composite bioceramics was worked out.ZrO₂-Al₂O₃ substrate with high strength was prepared by microwave sintering process,and the HA-W—Glass gradient bioactive coating was prepared on ZrO₂-Al₂O₃ ceramic substrate by microwave sintering.The effects of sintering temperature on the structure,phase trasition and the combination intensity between the coating and ceramic substrate were studied initially,the best sintering temperature was decided.Microwave sintering is beneficial to the compaction of the HA ceramic body,to realize the fast sintering of HA at low temperature and to increase the strength of HA ceramics.The effects of microwave sintering of HA-Glass composite are not as good as that of pure HA. The fast heating and sintering induces the porosity of HA-Glass composite ceramics,and its strength is lower than that of pour HA.Microwave sintering can accelerate HA decomposing, and the decomposing degree of HA will increase with the raising of sintering temperature and the prolonging of sintering period.Microwave sintering process can be used to prepare gradient coatings.HA-W-Glass gradient coating sintered by microwave has similar structure and properties as that of the gradient coating conventional sintered.But microwave sintering can realize fast sintering,shortening the sintering period and saving energy.4.The biomedicine properties of the HA-Glass-α-Al₂O₃ composite biomaterials were evaluated.On the bases of a series of safety evaluation tests,the degradation properties of composite biomaterials were studied by simulative experiments and little rat intramuscular implantation experiment.Simulative body fluid（SBF） immersion test was done and XRD, EDS and SEM techniques were used to study the surface bioactivity of HA-W-Glass gradient coatings.The results of biomedicine properties evaluating show that:The HA-R₂O-Al₂O₃-B₂O₃ -SiO₂ system glass-α-Al₂O₃ composite biomaterials have no toxicity to the organism,and do not induce to hemolysis and pyrogen reaction.The results of intramuscular implantation experiment show that the composite biomaterials have no irritation,and the phagocytosis of mutinucleate cells proves the composite biomaterials are biodegradable in some degree.The results of physics degradation experiment and weight loss analyses after intramuscular implantation show that the composition of the composite biomaterials has effects on the degradation properties of the materials,the HA and glass phase is propitious to the degradation and increase the bioactivity of the biomaterials,and it can increase the durability of the biomaterials to add the ultrafineα-Al₂O₃ in the composite biomaterials.So that the surface of HA-R₂O-Al₂O₃-B₂O₃-SiO₂ system Glass-α-Al₂O₃ gradient coating has better bioactivity and the inter layers of the gradient coating have nice durability.The results of SBF immersion test show that both of HA-W-Glass gradient coatings conventional sintered and microwave sintered at 1150℃have good surface bioactivity.A deposit layer of HA will form on the surface of the gradient coating after it is immersed in SBF for some periods.But the bioactivity of the coating will be lowered when it is sintered at 1200℃.更多还原