医用锆铌合金氧化陶瓷层的制备及其性能研究

发布时间：2018-07-25 17:00

【摘要】：锆合金具有良好的生物相容性、较好的综合力学性能、耐腐蚀性好等特性,可作为生物医学植入材料。然而,锆合金尚难以满足植入体在耐磨性、耐腐蚀性等方面的使用要求。氧化物陶瓷具有耐磨性好、耐蚀性强等优点,但易脆性断裂使其难以单独作为医学植入体的优先材料。有鉴于此,本论文结合金属和氧化物陶瓷的性能优势,以锆铌合金为研究对象,利用高温氧化方法在其表面原位形成陶瓷层,以获得表面高耐磨、整体高强韧的医学植入材料。同时,本论文还利用剧塑性变形细化锆铌合金的晶粒,对比研究氧化参数对不同晶粒尺寸锆铌合金氧化动力学、组织结构、力学性能、耐蚀性能和生物相容性的影响规律,以期获得综合性能更为优异的氧化陶瓷层。因此,本论文对医用锆铌合金的组织性能设计和工程应用,具有非常重要的科学和工程意义。首先,研究了Zr-2.1Nb合金在550~650℃保温8h的氧化动力学。开始阶段氧化增重遵循抛物线规律,但在650℃约4h氧化增重转变为线性规律,发生氧化转折现象,此时氧化层中所含t-Zr O2向m-Zr O2转变速度的增加以及明显的裂纹缺陷引起氧化层保护作用的破坏。在550℃氧化6h、600℃氧化4h以及650℃氧化1h的优选氧化工艺条件下,获得了足够厚、少或无缺陷的4-6μm厚氧化陶瓷层,其维氏硬度为987HV,为基体金属硬度220HV的5倍;沿着氧化层截面方向,硬度逐渐下降直至基体的硬度,表明存在一个厚度约5?m的富氧扩散层;另外,由于表面生成的氧化陶瓷硬化层,使氧化后的锆铌合金屈服强度提高了70MPa。随后,研究了轧制形变量为60%锆铌合金的高温氧化行为。结果表明,与未形变的锆铌合金相比,形变对锆铌合金在550~650℃的氧化动力学机制并未产生明显影响,但氧化增重更小。由于形变合金细化的晶粒和存在的内应力使得氧化层中t-Zr O2的体积分数更高,有利于提高氧化层的致密性,故其氧化陶瓷层的表面硬度大幅提升,最高可达1217HV。此外,形变还大幅增加富氧扩散层的厚度、减缓其硬度下降的趋势,富氧扩散层最厚可达35?m,远深于未变形合金所形成的近5?m的富氧扩散层。经过600℃氧化4h后形变锆铌合金的塑性从19.4%大幅增加至32.6%,而强度未明显下降。对比研究了锆铌合金、氧化锆铌合金及形变氧化锆铌合金的耐磨性能。结果表明,氧化后锆铌合金的耐磨性能明显优于基体合金,其中表面氧化层硬度更高、更致密的形变氧化锆铌合金的耐磨性能最优。特别是在较小的载荷力条件下(25N),氧化锆铌合金在磨损20min时其磨损量仍低于2mg,表现出更优异的耐磨性。研究了锆铌合金、氧化锆铌合金及形变氧化锆铌合金的耐腐蚀性能。在林格模拟体液中,三种合金的稳定性分别是形变氧化合金氧化合金基体合金。同时,经过氧化的合金的腐蚀速率较基体低2-3个数量级,其中氧化陶瓷层的致密性也明显影响其耐腐蚀性,形变氧化合金腐蚀速率最低,表现出更为优异的耐腐蚀性。另外,细胞毒性实验表明,三种锆铌合金对细胞的毒副作用影响均较小,毒性低于Ⅰ级,显示出优异的生物相容性。其中形变氧化合金的耐腐蚀性与生物相容性最优,更适合用作生物医用材料。
[Abstract]:Zirconium alloys have good biocompatibility, good comprehensive mechanical properties, good corrosion resistance and so on, which can be used as biomedical implants. However, zirconium alloys are difficult to meet the requirements of wear resistance and corrosion resistance of the implants. Oxide ceramics have the advantages of good wear resistance and strong corrosion resistance, but brittle fracture makes it easy to fracture. It is difficult to be used as a priority material for medical implants. In view of this, this paper combines the performance advantages of metal and oxide ceramics, using the zirconium niobium alloy as the research object, using the high temperature oxidation method to form the ceramic layer on its surface in order to obtain the high wear resistance, high strength and toughness of the medical implant material. The grain of zirconium niobium alloy is refined by sexual deformation, and the influence of oxidation parameters on the oxidation kinetics, microstructure, mechanical properties, corrosion resistance and biocompatibility of zirconium niobium alloy with different grain sizes is studied in order to obtain a more excellent oxidation ceramic layer. Therefore, the structure and properties of the medical zirconium niobium alloy are designed and used in this paper. Engineering application is of very important scientific and engineering significance. First, the oxidation kinetics of Zr-2.1Nb alloy at 550~650 C for 8h is studied. At the beginning, the oxidation weight gain follows the parabolic law, but the oxidation weight of 4H is changed into a linear rule at 650 C, and the oxidation turning phenomenon occurs. At this time, the t-Zr O2 in the oxidation layer is transferred to m-Zr O2. Under the optimum oxidation process of oxidation of 6h at 550 degrees centigrade, 4H oxidation at 600, and oxidation of 1H at 650 C, a thick, less or no defect 4-6 mu m thick oxidation ceramic layer has been obtained at 550 degrees centigrade, and the hardness of the Vivtorinox is 987HV, which is 5 times of the matrix metal hardness 220HV, and along the oxidation layer. In the face direction, the hardness gradually descends until the hardness of the matrix, indicating the existence of an oxygen rich diffusion layer with a thickness of about 5? M. In addition, the yield strength of the zirconium niobium alloy after oxidation is increased by 70MPa., due to the oxidation ceramic hardening layer formed on the surface, and the high temperature oxidation behavior of the rolling variable is 60% zirconium niobium alloy. The results show that it is undeformed and undeformed. Compared with the Zr niobium alloy, the deformation has no obvious influence on the oxidation kinetics mechanism of Zr niobium alloy at 550~650 C, but the oxidation weight is smaller. Due to the grain refinement of the deformed alloy and the internal stress, the volume fraction of the t-Zr O2 in the oxide layer is higher, which is beneficial to the increase of the densification of the oxide layer, so the surface hardness of the oxidized ceramic layer is hard. In addition, the height can be up to 1217HV., and the deformation also greatly increases the thickness of the oxygen enriched layer and slows down the tendency of its hardness drop. The thickest oxygen diffusion layer is up to 35? M, which is far deeper than the oxygen rich diffusion layer of nearly 5? M formed by undeformed alloy. After 4H oxidation, the plasticity of the deformation zirconium niobium alloy increases from 19.4% to 32.6%, and the strength of the alloy is strong to 32.6%. The wear resistance of zirconium niobium alloy, zirconium niobium oxide alloy and deformed zirconium niobium alloy is compared and studied. The results show that the wear resistance of the zirconium niobium alloy after oxidation is obviously better than that of the matrix alloy, of which the surface oxidation layer is higher, and the more compact deformed zirconium niobium alloy has the best wear resistance, especially in the smaller load. Under the stress condition (25N), the wear resistance of Zr niobium alloy is still lower than that of 2mg at 20min. The corrosion resistance of zirconium niobium alloy, zirconium niobium alloy and deformed zirconium niobium alloy is studied. The stability of the three alloys in the simulated body fluid of Ringer's alloy is a deformed alloy oxide alloy matrix alloy. At the same time, the corrosion rate of the oxidized alloy is 2-3 orders of magnitude lower than that of the matrix, and the densification of the oxidized ceramic layer also obviously affects its corrosion resistance, the corrosion rate of the deformed alloy is the lowest and the corrosion resistance is more excellent. In addition, the cytotoxicity test shows that the toxic and side effects of the three kinds of zirconium niobium alloys are small, The toxicity is lower than grade I and shows excellent biocompatibility. The corrosion resistance and biocompatibility of the deformed alloy are best, and it is more suitable to be used as a biomedical material.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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