生物活性玻璃的制备及其组织性能研究

【作者】 马杰；

【导师】 陈传忠；

【作者基本信息】 山东大学 ， 材料学， 2007， 硕士

【摘要】 本文采用高温熔融法制备了Na₂O-CaO-P₂O₅-SiO₂系生物活性玻璃粉末及块体材料，并采用激光熔覆的方法于钛合金表面制备了生物玻璃涂层。通过X射线衍射（XRD）、扫描电镜（SEM）、电子探针（EPMA）、傅立叶红外转换光谱（FTIR）等测试方法对生物玻璃的内部基团、物理、化学性能及生物活性进行了表征，对钛合金表面激光熔覆层的微观组织形貌进行了研究。实验结果表明，生物玻璃粉末及块体材料均呈非晶态，内部基团主要含有Si-O（s）拉伸振动峰、Si-O（r）摇摆振动峰及Si-O（b）弯曲振动峰三种不同振动模式的Si-O基团及非桥氧键（Si-O-NBO）。不同熔融温度下制备的生物玻璃，除熔融过程中钠的挥发导致Na₂O含量与设计值差别较大外，其它氧化物含量均与其设计值相近。生物玻璃于NaOH溶液中浸泡后，试样表面表现出明显的腐蚀沟槽和裂纹，且浸泡腐蚀过程中腐蚀速率逐渐减小，浸泡50天后玻璃质量趋于稳定。生物玻璃粉末及块体材料模拟体液浸泡实验中，试样表面形貌变化显著。实验结果表明，浸泡过程中生物玻璃表面先后生成富含Si元素的SiO₂溶胶凝胶层及富含Ca、P元素的Ca-P层，且Ca-P层上富集众多球形颗粒，能谱分析结果显示，球形颗粒主要含有Ca、P元素，且Ca／P化学计量比为1.624，与羟基磷灰石Ca／P计量比（1.667）接近。X射线衍射分析结果表明，生物玻璃外层表面生成的Ca-P富含层为羟基磷灰石及部分碳酸羟基磷灰石。生物玻璃模拟体液活性实验结果表明，生物玻璃表面经过离子交换、水解作用后形成的SiO₂溶胶凝胶层，为磷灰石形核提供了形核位置，降低了其非均匀临界形核半径（r^*）和临界形核功（△G^*）。在凝胶层Zeta电势的作用下，模拟体液中的Ca、P离子于SiO₂溶胶凝胶层上聚集，且由于模拟体液中的过饱和磷灰石离子活度积IP，磷灰石晶核一旦形成便自发长大。在本实验条件下，钛合金表面激光熔覆生物玻璃粉末及生物玻璃与钛粉混合粉末均可得到表面宏观形貌质量较好的涂层，且涂层表面具有明显的陶釉特征。激光表面熔覆层X射线衍射图谱结果表明，衍射峰重合严重，除少数主峰外，其它峰密而弱，存在着一定的弥散现象。生物玻璃熔覆涂层物相主要由CaTiO₃构成，另外含有AlP，Al₂O₃，Ti₇Al₅Si₁₂及Ti₂O₃等物相。混合粉末涂层由于钛粉的加入，熔覆后表面熔覆层中Ti₂O₃含量明显提高。激光熔覆后涂层与基体可得到良好的冶金结合，熔覆层中凝固组织在温度梯度及成分梯度的共同作用下发生从胞枝晶到柱状树枝晶到等轴晶的形貌变化。更多还原

【Abstract】 The system of Na₂O-CaO-P₂O₅-SiO₂ bioactive glass powder and blocks were prepared using traditional high-temperature melting method and the bioactive glass coatings on titanium alloy were fabricate using laser cladding in this paper. The microstructure, physics and chemical properties, bioactivity of bioactive glass and laser cladding coating were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, electron probe microanalysis （EPMA） and Fourier transform infrared spectroscopy （FTIR）.The results show that bioactive glass display amorphous state, and the internal structure of it mainly contains three different modes of Si-0 vibration groups, such as Si-O（s） stretching vibration, Si-O（r） rocking vibration and Si-O（b） bending vibration. It is also observed that the chemical composition is acceptable for silicon, calcium and phosphorus while the loss of sodium is observed obviously. The reason can be explained by that sodium is thought to be the most volatile element. From the test of immersing in alkaline sodium hydroxide, we find that bioactive glass show more surface corrosion pits and significant corrosion grooves and cracks. And during the immersion corrosion process, it demonstrates that the corrosion rate gradually reduces, and after 50 days immersion, the mass of bioactive glass move toward stability.The significant changes have happened on the glass surface while immersed in simulated body fluid for different time. It indicates that glass surface generates silica sol-gel layer and Ca-P layer in turn during immersion. And in the top of external Ca-P layer, there exists numerous spherical granules, which have the similar atomic Ca/P ratio to that of hydroxyapatie. The Ca-P rich layer is identified as hydroxyapatite and carbonate hydroxyapatite by XRD. In addition, the researches of surface reactions on bioactive glass show that SiO₂-gel layer is produced after a serial effects of ion exchange, condensation and repolymerization, and gel layer possessing the open structure accelerates the nucleation of apathies by reducing the critical nucleus radius （r^*） and the activation energy barrier against heterogeneous nucleation（△G^*）. Then under the effect of Zeta potential, the Ca, P ions in simulated body fluid are accumulated on the surface of SiO₂-gel layer. Once apatite nuclei occur on the surface of gel layer, it can grow up spontaneously because of the supersaturated apatite positive ions （IP） of SBF.In this experiment, laser cladding coating shows good quality and reveals the distinct characteristics of the ceramic. XRD spectra show that most diffraction peaks coincide seriously and close to weak, except a few peaks, it shows partly dispersion pheromone. For single bioactive glass cladding coating, it mainly consists of CaTiO₃ phase and A1P, Al₂O₃, Ti₇Al₅Si₁₂, Ti₂O₃. While mixed cladding coating consists of more Ti₂O₃ beside CaTiO₃, for the addition of titanium powder in coating. After been laser cladding, the coating form compact combine between each other and show fine metallurgical combination. The microstructure of cladding coating changes from dendrite to columnar dendrite to equiaxed crystal at the effect of temperature and composition gradient.更多还原