【作者】 胡伟；

【导师】 徐江；

【作者基本信息】 南京航空航天大学 ， 材料学， 2016， 硕士

【摘要】 近年来,钛及其合金由于其较低的密度、高比强度以及良好的生物相容性等优点已被大量应用于航空航天、汽车工业以及医疗设备的制造。但是,钛合金在使用过程中出现的种种问题,诸如作为生物材料在长期使用过程中,合金元素离子可能会渗入血液或是在材料的表面形成血栓,都会对使用者造成巨大伤害;钛合金自身摩擦系数大、耐磨性差以及在恶劣条件下耐蚀性能差等固有的缺点都阻碍了它们的应用范围的进一步扩大。众所周知,材料的磨损和腐蚀性能是材料表面控制的降解过程,因此表面改性技术是提高钛合金表面相关性能的最有效手段之一。钽系材料具有生物无毒性,耐磨耐蚀性能优越等特点,钽及其氧化物（Ta-O）、氮化物（Ta-N）以及其他化合物薄膜/涂层材料已经在生物医学、机械等行业得到了广泛的关注。本课题提出采用双阴极等离子溅射沉积技术在光滑的Ti-6A1-4V合金表面制备出了Ta₂O₅和TaON两种涂层。所制备涂层横截面SEM表明涂层微观组织连续、致密,无孔洞、裂纹等明显缺陷,涂层厚度均为²5μm且与基体良好结合;TEM分析表明所制备纳米晶涂层微观结构由15nm左右大小的等轴晶粒组成的;纳米压入测试表明两种涂层都极大提高Ti-6Al-4V的硬度及弹性模量;划痕测试分析表明所制备纳米晶涂层与基体具有良好的结合力。干摩擦条件下,两种涂层在载荷从2.3N至5.3N下比磨损率约在10-6 mm3 N-1 m-1范围内,较Ti-6A1-4V合金降低约2个数量级。采用电化学测试方法分别研究了两种涂层在模拟人体体液（0.9 wt.%NaCl和Ringer’s溶液）和3.5 wt.%NaCl中不同浸泡时间条件下的耐腐蚀性能。电化学实验分析结果表明:无论是在模拟人体体液中还是在3.5 wt.%NaCl溶液中,所制备的两种涂层的耐腐蚀性能较Ti-6Al-4V有显著的提高,且随着浸泡时间的延长他们的耐腐蚀性能基本保持不变。通过Mott-Schottky理论计算和PZC分析表明,两种涂层材料相比较Ti-6Al-4V而言,具有更低的载流子密度和更强的抑制吸附Cl-的能力。最后,两种纳米晶涂层在Hank’s溶液中浸泡15天后实验结果表明,涂层表面有絮状磷灰石层形成,这有利于涂层材料在生物活体中能够快速的骨整合。更多还原

【Abstract】 In recent years, titanium and its alloys have been widely used in manufacture of aerospace, automotive industries and medical devices owing to its favorable properties, such as low density, high strength-to-weight ratio, superior biocompatibility, etc. However, many problems have been found in the application of titanium alloys. For instance, as long-term use biomaterial in human body, the alloy element ions may release into the blood or thrombus format on the surface of material, which can cause heavily harm to their users;titanium alloys also suffer from serious disadvantages of poor tribological properties and they also exhibitpoor corrosion resistance in some aggressive environment, all of these inherent shortcomings of titanium alloy have been greatly hindered them from being extensively applied. As is well known to all of us, both wear and corrosion are surface-controlled degradation processes. Therefore, surface modification technology could be one of the most effective means to improve the surface-relative performances of titanium alloy.Tantalum-based materials possess biological nontoxic, excellent wear and corrosion performance characteristics, tantalum and its oxide（Ta-O）, nitride（Ta-N） and other compound thin films or coatings have been gained much attention in biomedicine, machinery and some other industries. In this paper, Ta₂O₅ coating and TaON coating were deposited onto the polished surface of Ti-6A1-4V alloy by double cathode glow discharge technique. The cross-section SEM images show that both of the coatings, with a uniform thickness of ²5 μm, exhibits an extremely dense and homogeneousmicrostructure, and appears to be well adhered to the Ti–6Al–4V substratewithout any visible defects. TEM images indicate both of the coatings have the similarmicrostructural characteristics, composed of equiaxed grains with an average grain size of ¹5 nm.Nanoindentation tests show that the coatings can greatly improve the hardness and elastic modulus of Ti–6Al–4V alloy. Scratch tests show the adhesion strength between the coatings and the substrate is enough for engineering application. Under dry sliding wear conditions, the specific wear rates of the coatings were of the order of 10-6 mm3 N-1 m-1 under applied loads ranging from 2.3N to 5.3N and are two orders of magnitude smaller compared to uncoate Ti-6Al-4V alloy. Electrochemical tests were employed to analysis the corrosion behavior of the two coatings in simulatedbody fluids（0.9 wt.% NaCl solution and Ringer’s solution） and 3.5 wt.% NaCl solution.The electrochemical experiment results show that: both in simulatedbody fluids and in 3.5 wt.% NaCl solution, the two as-deposited coatings can remarkly enhance the corrosion resistance of the Ti-6Al-4V alloy, andthetheir corrosion resistanceappear almost independent with the soaking time. Mott–Schottky analysis and potential of zero charge（PZC） measurements indicate that both the Ta₂O₅ and TaON coating exhibited a lower carrier density and a larger capability to inhibit the adsorption of aggressive chloride ions than uncoated Ti–6Al–4V.At last, the two nanocrystalline coatingswere soaked in Hank’s solution for 15 days and the results showed that the apatite layer was formed on both of the surfaces, which is beneffical to the coating materials’ rapid osseointegration in the living body.更多还原