磷酸钙盐/Al₂O₃-金属生物复合材料体系的制备与表征

【作者】 吴振军；

【导师】 陈宗璋； 何莉萍；

【作者基本信息】 湖南大学 ， 物理化学， 2003， 硕士

【摘要】 由于可同时具备良好的生物相容性与优异的机械力学性能，磷酸钙盐／金属复合材料被认为是最有希望应用于硬组织修复与替换的体系之一。目前所开发的技术，如等离子喷涂、离子束辅助沉积和溶胶-凝胶等，已证明很难在金属表面构造持久可靠的磷酸钙盐生物陶瓷涂层。而包括电结晶、电泳沉积、电镀共沉积和阳极氧化等在内的电化学涂层制备技术，由于工艺简单、可在表面形貌复杂的基体上制备均一复合生物涂层，在硬组织材料领域具有很高的应用价值。 本文以高纯Ti表面物理气相沉积（PVD）Al膜的Al-Ti为基体材料，采用阳极氧化-水热处理复合制备技术制备磷酸钙盐-Al₂O₃／Al-Ti生物复合材料体系；另外，采用先阳极氧化，再分别用NaH₂PO₄和Ca（OH）₂溶液浸渍处理，最后于模拟体液（SBF）中诱导沉积的多步法成功构造了钙磷陶瓷-Al₂O₃／Al复合材料体系。利用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、原子力显微镜（AFM）、X射线电子能谱（EDAX）、X射线衍射（XRD）表征了阳极氧化前后铝膜和钙磷生物陶瓷涂层的微观形貌、元素构成以及晶相成分。研究结果表明： （1）采用物理气相沉积法在Ti片表面制备了厚度为1～5μm的纯铝膜。铝膜厚度与偏转电压、沉积时间、Al靶电流以及基底材料的导电性能等PVD处理参数相关；其中，沉积时间和Al靶电流对铝膜厚度的影响最为明显；铝膜表面粗糙度则受制于Ti片抛光程度以及铝膜厚度。 （2）采用阳极氧化及水热处理复合技术，成功研制出了具有纳米、纤维管状结构特征的块状磷酸钙盐-Al₂O₃／Al-Ti生物复合材料新体系。将Al-Ti基底在以乙酸钙和β-甘油磷酸钠为主要组分的电解质中阳极氧化，合成了含有Ca、P元素的多孔氧化铝膜，膜孔大小介于10～50nrn之间，呈疏散排布；氧化程度较高的多孔氧化铝膜宜在30～60V电压下制备。上述阳极氧化膜经水热处理，得到了内部致密、外部疏松，由长150～250nm，宽100nm的酸性磷酸钙和三斜磷酸钙块状晶体构成的生物陶瓷涂层。 块状晶体以212℃，2.0MPa条件下水热生长8h为宜；在去离子水中性环境中，此陶瓷涂层晶体的形核与长大速率相当。 （3）提高电解质中钙源与磷源浓度，制成了含有更多Ca、P元素，针孔孔径在30～80nm间的多孔氧化铝膜。将此阳极氧化铝膜在稀磷酸水溶液（1：800）中212℃，2.0MPa条件水热处理8h，构造了由直径为7～30nm、长度为200～650m并相互交连成网状的磷酸钙盐（水合CaHPO₄（brushite）与CaHPO₄（monetite））针状晶体构成的陶瓷涂层，该钙磷涂层具有一定的仿生结构特征。 浓度差、电势差分别是Ca、P元素进入多孔氧化铝膜的主要推动力，且Ca、P元素可能分别以Cao、[P 04]基团的形式进入多孔氧化铝膜，写出了相关的化学反应方程式。进一步证明了酸性介质是针状钙磷陶瓷晶体生长的必要条件。 （4）AI片在磷酸溶液中进行恒直流阳极氧化经历了致密阻挡层的快速形成、多孔层的初步生长以及多孔层孔洞的进一步发展三个连续阶段。获得了孔径在50-15Onln之间的大孔洞。而Al片在碱性的磷酸钠介质中恒电压处理时发生了过氧化行为，形成了在直径150一Zoonm的大坑（或称之为浅洞）底部分布着直径为30礴Onln的大量细孔的多孔氧化铝膜。 经预浸渍加仿生矿化沉积多步处理，上述多孔膜表面均能诱导沉积钙磷陶瓷涂层，这归因于多孔氧化铝能够吸附磷酸钙盐晶体生长所需的P04H:活性基团;且过氧化多孔氧化铝膜吸附PO4HZ基团的能力要比常规多孔氧化铝膜强。目前对钙磷陶瓷/金属体系的交流阻抗谱研究预示了仿生沉积钙磷陶瓷/A 1203复合涂层极有希望用于制作硬组织领域用生物传感器。更多还原

【Abstract】 Calcium phosphate/metal composite, which may simultaneously achieve good biocompatibility and good mechanical properties, is expected as one of the most suitable systems for hard tissue repair and replacement. It is reported that calcium phosphate bioceramic coatings on metals with reliable and long-life performances cannot be easily obtained by using some developed technologies, such as plasma spray, ion beam assistant deposition, thermal spray deposition, and sol-gel method. Due to their simple preparation arts and the ability of obtaining uniform composite biocoatings on substrates, the electrochemical methods, which include electrocrystallization, electrophoretic deposition, electro-codeposition, and anodization, are considered to be useful for the application as artificial implant materials.In this study, pure Al thin film was PVD-deposited on medical titanium to form Al-Ti substrate. Al-Ti substrate was then applied to the hybrid technique of anodization and hydrothermal treatment to fabricate nanometric calcium phosphate/Al2O3 porous biocomposite coating on Al-Ti substrate. In addition, calcium phosphate/Al2O3-Al composite was prepared via a multi-step method, that is Al-Ti substrates with Al as the surface layer were anodized firstly, and then were subsequently immersed in NaH2PO4 and Ca(OH)2 solutions, respectively, followed by a biomimetic process conducted in a simulated body fluid (SBF). Techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDAX), and X-ray diffraction (XRD), were employed to study the microstructures and compositions of Al thin film, porous alumina films (PAFs) and calcium phosphate/Al2O3 biocomposite coatings. The results are indicated as bellows:(1) Pure Al films, thickness 1-5 n m, were deposited on Ti after PVD process. The thickness of Al films was correlated with bias voltage, deposition time, Al target current, and the substrates’ conductivity. The deposition time and Al target current had strong effects on Al film thickness than other factors. The roughness of Al film mainly depended on the topography of Ti discs and the thickness of Al films.(2) The hybrid technique of anodization and hydrothermal treatment has led to the successful fabrication of calcium phosphate-Al2O3/Al-Ti biocomposite. During theanodization of Al-Ti substrates in electrolytes containing calcium acetate (CA) and beta -Glycerol phosphate disodium(beta -GP), the elements Ca and P were incorporated into the PAFs layer with columnar pores in the rage of 10~50nm. Additionally, cell voltages between 30V and 60V are the optimal voltage for getting high anodization degree PAFs. It is also found that after hydrothermal treatment, acidic calcium phosphate (Ca4H2(P3O10)2) and monetite formed bioceramic coatings with a specific compact-bottom and loose-top structure.It seems that 8h is a suitable growth time of as-prepared cloddy crystals, and that the nucleation rate of this kind of ceramic coating crystals is close to their growth rate in deionized water.(3) By increasing the concentrations of Ca and P sources in the anodization electrolyte, PAFs containing much more Ca and P elements were synthesized. After hydrothermally treated at 212癈 and 2.0MPa in a diluted phosphorous acid (1 I 800) for 8h, bioceramic coatings consisted of needle-like brushite and monetite were prepared. And the needle-like crystals cross-linked together resulted in the formation of biomimetic coatings with specific microstructures.It is also found that concentration gradient and potential difference are the main driving forces for the incorporation of Ca and P into PAFs layer. It seems that Ca and P existed in PAFs were in the forms of CaO and [PO4] groups, and some related chemical reactions were proposed. Further on, it is demonstrated that the acidic media is essential for the growth of needle-like calcium phosphate crystals.(4) During galvanostatic anodized in phosphorous acid, several processes happened on Al thin films: the form更多还原