【作者】 钱备；

【导师】 李淑英；

【作者基本信息】 大连理工大学 ， 生物医学工程， 2011， 硕士

【摘要】 钛及其合金以其优异的性能,在医用植入领域获得广泛应用。但医用钛材料作为种植体目前仍存在一些急待解决的问题,如在人体十分苛刻应用环境中的耐蚀性需进一步提高。这些问题与钛材料的表面性能密切相关,而电化学抛光和阳极氧化是两种重要的钛表面处理技术,是提高钛表面耐蚀性能的有效途径。另外,钛不仅用于医学,在航空航天、军事领域、石油化工和海洋环境中的应用也日益广泛。本文研制出一种新型无毒环保的电化学抛光液,以钛材表面的光亮度、粗糙度及表面形貌为主要评价指标,用电化学极化曲线测试方法、粗糙度测试仪、扫描电镜等测试技术,考察了电压、时间、温度及阴阳极间距对抛光效果的影响规律,经与传统的机械抛光、化学抛光方法对比表明：所得到的电化学抛光液优于其它两种方法,经该抛光液处理后的试样表面平整、光亮如镜,表面粗糙度约为0.09gm,自腐蚀电流密度最小耐蚀性能显著提高。其最佳工艺参数为槽压30V,时间180s,温度50℃,阴阳极距离2cm。采用极化曲线、交流阻抗和Mott-Schottky曲线等电化学测试技术,分别研究了硫酸、磷酸电解液中钛阳极氧化膜在生理盐水中的腐蚀行为,以及硫酸铵、硫酸和磷酸电解液中钛阳极氧化膜在高温含溴醋酸中的腐蚀行为。研究结果表明：阳极氧化后的试样自腐蚀电位上升,自腐蚀电流密度下降,耐蚀性能显著提高。磷酸介质中钛阳极氧化膜与硫酸介质中相比,在低频区阻抗较大,载流子密度较大,平带点位更负,耐蚀性能好；未经阳极氧化试样在高温含溴醋酸中出现点蚀破裂电位。氧化膜颜色和膜厚随着阳极氧化电压的升高而变化,但耐蚀性受电压变化的影响较小。将阳极氧化后的钛与碳钢以8：1的面积比偶接,采用CS300电偶电流测试技术连续记录了该电偶对在模拟海水中8小时的电偶电流值,经与未氧化处理的电偶对相比结果表明：钛经阳极氧化后可使电偶对的电偶腐蚀电流密度减小。纯钛与碳钢的电偶电流密度为175μA左右；磷酸工艺电压为40V时电偶对的电偶电流密度接近40μA,硫酸工艺电压为40V时电偶对的电偶电流密度接近80μA;钛阳极氧化膜在整个电偶反应的体系中相当于额外的电阻极化。更多还原

【Abstract】 Titanium and titanium alloy are widely used in biomedical materials due to their biocompatibility, excellent corrosion resistance, good mechanical properties and lightness. However, there are some problems need to be solved right now. Such as the corrosion resistance of titanium should be improved. The surface property of titanium is related to these problems. Electropolishing and anodizing are both important surface technologies for titanium, which are good ways to improve the corrosion resistence of titanium. In addition, titanium has a good prospect of application in aviation, military, chemical industry and oceamcs.In this paper, a new environmental friendly and non-toxic electropolishing technology was proposed. Surface brightness, roughness and surface modality were main standard used for study the condition. We used potentiodynamic polarization curve, roughness reader and SEM to study the influence of voltage, time, temperature and distance between electrodes. What’s more, we compared electropolishing technology with the traditional mechanical polishing and chemical polishing. The results showed that titanium after electropolishing got more smooth surface and was mirror like. The roughness of surface was about 0.09μm, which also had lower icorr, thus showed better corrosion resistance. The optimal condition was 30V, 180s,50℃and 2cm.The corrosion behavior of titanium and after anodizing in H2SO4 and H3PO4 was studied by potentiodynamic polarization curve, EIS and Mott-Schottky plots in physiological saline solution. And the corrosion behavior of titanium after anodizing in (NH4)2SO4, H2SO4 and H3PO4 was investigated by potentiodynamic polarization curve, EIS in Br- containing acetic acid solution. The results indicated that titanium after anodizing showed higher self-corrosion potential, lower icorr. Compared with the blank sample, the corrosion resistance were improved largely when titanium after anodizing. EIS exhibited higher impedence values in the low frequency range for films anodized in phosphoric acid. Meanwhile the Mott-Schottky plots showed lower donor density and lower flat band potential for titanium anodized in H3PO4, which reflected better corrosion resistance than titanium anodized in H2SO4. The breakdown potential of the pitting is observed for blank sample in Br- containing acetic acid solution. But it was not found when titanium after anodizing in (NH4)2SO4, H2SO4 and H3PO4. It was also found that the color and thickness of the film were changed with the voltage except the corrosion behavior.The galvanic corrosion generated between titanium after anodizing and carbon steel pair in area ratio at 8:1 for 8 hours in simulate seawater was studied by CS300. Compared with the blank sample, the results showed that galvanic current densities were reduced largely after titanium anodizing. Galvanic current densities was 175μA for blank sample galvanic pair. Galvanic current densities was 40μA for titanium anodizing in H3PO4 for 40V and 80μA for titanium anodizing in H2SO4 for 40V. The anodic oxide films lead to an IR drop in the system.更多还原