【作者】 王石磊；

【导师】 汪涛；

【作者基本信息】 南京航空航天大学 ， 材料加工工程， 2009， 硕士

【摘要】 针对目前硬组织替代用钛合金植入体表面生物陶瓷涂层与基体间界面结合差,在受力和疲劳情况下容易剥落,以及生物陶瓷材料性脆易断裂,植入人体后易早期断裂失效等关键问题,开展了低成本、高性能的生物陶瓷涂层材料与生物陶瓷复合材料研究。本论文通过涂层材料与钛合金基体间的热膨胀系数的匹配设计,优化涂层/基体界面结合,在钛合金基体上沉积六钛酸钾(K2Ti6O13)和K2Ti6O13/HA(羟基磷灰石)生物陶瓷涂层,以获得具有良好生物活性、较高结合强度和耐磨性能的生物活性涂层。首先通过固相反应和化学沉淀法分别制备了K2Ti6O13和HA粉体,确定了粉体的合成工艺,并对其进行了表征;然后用等离子喷涂的方法在Ti-6Al-4V合金基体上分别制备了K2Ti6O13和K2Ti6O13/HA生物陶瓷涂层;利用XRD和SEM技术对材料的相组成和表面与截面形貌进行表征,按照ASTM C-633标准对涂层的结合强度进行了检测,利用摩擦磨损试验机检测了涂层的抗摩擦性能,利用模拟体液培养和傅立叶红外光谱分析了其生物活性。结果表明,本研究所制的K2Ti6O13具有与Ti-6Al-4V相近的热膨胀系数,通过计算可知K2Ti6O13与HA的重量配比为80%:20%时,K2Ti6O13/HA生物陶瓷涂层的热膨胀系数与Ti-6Al-4V合金一致。通过正交实验获得等离子喷涂的最佳工艺参数:电压39.8V,电流850A,主气45L/min,辅气27.9L/min,距离100mm。在此参数下,Ti-6Al-4V合金基体上K2Ti6O13和K2Ti6O13/HA涂层均具有最大的结合强度,分别为20MPa和23.7MPa。所制备涂层厚度为50~100μm。磨损实验表明涂层可以有效地提高钛合金的耐磨性。通过涂层组织观察现,涂层具有凹凸不平的表面,该表面有利于骨组织的长入。物相分析结果表明,复合涂层中K2Ti6O13与HA有相互助熔的作用,并且两者反应生成了TiO2等新物质。涂层经模拟体液培养后,发现K2Ti6O13/HA涂层表面有钙磷层沉积,具有较好的生物活性。另外,本研究还采用冷压成型+1050℃、1100℃、1150℃和1200℃无压大气烧结的方法制备了K2Ti6O13生物陶瓷和HA含量分别为25%、50%、75%和100%的K2Ti6O13晶须/HA复合生物陶瓷。然后利用XRD和SEM对材料的相组成和表面与断面形貌进行了表征,检测了其线收缩率、体积密度和气孔率等物理性质,测试了陶瓷的抗弯强度,并通过模拟体液培养试验表征了生物陶瓷的生物活性。试验结果表明,1100℃烧结的K2Ti6O13陶瓷具有最大的的抗弯强度120MPa;复合陶瓷在1150℃和1200℃时烧结致密,HA含量为50%时具有最大的抗弯强度160MPa。单相K2Ti6O13陶瓷烧结后晶须会熔合成粗大而多孔的柱状晶,强度会有所降低,晶相并未发生大的改变。在复合生物陶瓷体系中,HA能促进K2Ti6O13陶瓷发生相变反应,随着HA含量的增加和烧结温度的升高复合陶瓷中的K2Ti6O13逐渐转变为TiO2,部分TiO2会与HA反应生成CaTiO3,或促进其分解生成TCP。1150℃烧结含50%HA的复合陶瓷不仅具有较大的抗弯强度,可达159MPa,而且经模拟体液培养发现,7天就会长出钙磷层,随着培养时间的延长钙磷层会变的厚且致密。同时,1150℃烧结含75%HA的复合陶瓷也具有很好的生物活性,而K2Ti6O13陶瓷的生物活性不太明显。更多还原

【Abstract】 At present, the researches on the low-cost high-performance bioceramic coatings and bioceramic materials were developed and investigated in order to deal with the peeling of the bio-active coating from the surface of Ti-implant due to poor coating/substrate interfacial bonding, as well as the early in-vivo fracture due to the inherent brittleness of bioceramic materials.By matching the coefficients of thermal expansion (CTE) between coating material and substrate, the K2Ti6O13 and K2Ti6O13/hydroxyapatite(HA) were designed for the bio-active coatings on Ti-6Al-4V alloy implant with better bio-activity, stronger interfacial bonding, as well as higher wear resistance for bone substitution.K2Ti6O13 and HA powders were prepared by solid-state sintering and co-precipitation, respectively. The K2Ti6O13 and K2Ti6O13/hydroxyapatite(HA) bio-active coatings were sprayed on Ti-6Al-4V alloy by plasma spraying method. The phasic composition and transformation of the sprayed coating were studied by X-ray diffraction(XRD). The morphologies of the coating surface and interface between the substrate and coating were studied using scanning electron microscopy(SEM). The relationship between the microstructure of coating, mechanical properties and biological properties was studied as well. The coating bonding strength was tested according to ASTM C-633 standard, and the friction performance was examined by the grinding abrasion testing machine. The bioactivity of the sample was studied by cultivating it in simulation body fluid (SBF) and by Fourier Transform Infrared Spectra(FT-IR).According to the determined CTEs of K2Ti6O13 and Ti-6Al-4V, The two have the similar CTEs, and the CTE of the composite material which comprising of K2Ti6O13 and HA at the weight ratio of 80% : 20% is coincide with that of the Ti-6Al-4V. Utilizing the orthogonal experiment, the spray coating technological parameters were obtained as following: voltage 39.8V, electric current 850A, the main gas 45L/min, auxiliary gas 27.9L/min, as well as spray distance 100mm, under which the maximal bonding strengths of the resulted K2Ti6O13 and K2Ti6O13/HA coatings on Ti-6Al-4V were obtained as 20MPa and 23.7MPa respectively.The results indicate that the coating and the substrate are bonded well and the thickness of coating is between 50~100μm. The appearance of coating improves the wear-resisting property of Ti-6Al-4V alloy effectively. According to the SEM observations, rough areas can be formed on the coating surface, which is useful for bone cell to grow into. The XRD results indicate that some chemical reaction partially happened between K2Ti6O13 and HA during spraying, producing a mount of TiO2 and CaTiO3 as the reaction products. After being immersed in simulation body fluid (SBF) for 5 days, a few calcium phosphates was deposited on the coating, which indicates that the K2Ti6O13/HA bioceramic coating is of a good bio-activity.Furthermore, pure K2Ti6O13 bioceramic and K2Ti6O13 whisk reinforced HA composite bioceramic with 0%, 25%, 50%, 75% and 100% HA, were produced by cold-pressing and atmospheric pressureless sintering method at 1050℃, 1100℃, 1150℃and 1200℃, respectively. Detected its surface and interface morphology with SEM, analysed its phase structure with XRD, and analysed its physics performance such as liner shrinkage、density and porosity. Measured the bending strength of the bioceramic, it is revealed that the K2Ti6O13 bioceramic which sintered at 1100℃has the biggest bending strength, and 50% HA content composite ceramic had the biggest bending strength whether sintered at 1150℃or 1200℃. The phasic composition and transformation of the composites were studied by XRD. The morphologies of the sintered bioceramics were observed using SEM. The values of linear shrinkage, volume density and porosity of the sintered specimens were measured too. Finally, the bending strength and biological properties was characterized as well.The results show that K2Ti6O13 bio-ceramic specimen is of the maximum bending strength 120MPa after sintering at 1100℃, whereas the K2Ti6O13 whisk/HA composite bioceramic became compact after sintering at 1150℃and 1200℃. The bending strength of 50%HA composite bioceramic is obtained as 160MPa, the maximum value of the composites. It is found in pure K2Ti6O13 specimen, K2Ti6O13 whisks melted and agglomerated into coarse porous columnar grains during sintering without phase changes, which results in the decrease of strength. In composites, a chemical reaction partially happened between K2Ti6O13 and HA during sintering, producing with the reaction products of TiO2 and CaTiO3. After 7 days’ cultivation in SBF, a calcium phosphate layer appeared on the surface of the K2Ti6O13 whisk/HA composite ceramics, and became thicker and more compact with the extended cultivation period. But the bioactivity of K2Ti6O13 ceramic is not as good as that of the composite bioceramics. It is noticeable the 50%HA composite bioceramic sintered at 1150℃has a good bending strength (159MPa) and a very good bioactivity. And the 75%HA composite bioceramic sintered at 1150℃has a very good bioactivity too.更多还原