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1、硕 士 学 位 论 文钛电化学抛光及其阳极氧化膜的腐蚀行为研究Research on Electropolishing and Corrosion Behavior of Anodized Titanium作 者 姓 名： 钱备 学科、 专业： 生物医学工程 学 号： 20807406 指 导 教 师： 李淑英 完 成 日 期： 2011.5 大连理工大学Dalian University of Technology大连理工大学学位论文独创性声明作者郑重声明：所呈交的学位论文，是本人在导师的指导下进行研究工作所取得的成果。尽我所知，除文中已经注明引用内容和致谢的地方外，本论文不包含其他个人或集
2、体已经发表的研究成果，也不包含其他已申请学位或其他用途使用过的成果。与我一同工作的同志对本研究所做的贡献均已在论文中做了明确的说明并表示了谢意。若有不实之处，本人愿意承担相关法律责任。学位论文题目： 作 者 签 名 ： 日期： 年 月 日大 连 理 工 大 学 硕 士 学 位 论 文- I -摘 要电化学抛光和阳极氧化是两种重要的钛表面处理技术，前者是常用的金属前处理技术，后者被广泛应用于航空航天、医学、军事等领域。随着阳极氧化机理及工艺研究的进一步成熟，将其应用于海洋工程和石油化工领域迫在眉睫。本文提出并优化了一种新型环保无毒的电化学抛光工艺；以传统的硫酸和磷酸工艺对 TA2 进行阳极氧化，
3、考察其在模拟海水及高温含溴醋酸溶液中的腐蚀情况，为其实际应用提供一定的理论依据。本文以含氯离子的乙二醇溶液为抛光液对钛表面进行电化学抛光，通过抛光处理后金属表面的光亮度、粗糙度及表面形貌为主要评价指标，优选出最佳工艺条件为：槽压 30V，时间 180s，温度 50，阴阳极距离 2cm，试样表面如镜面光亮，表面粗糙度为 0.09m 左右。通过对机械抛光、化学抛光和电化学抛光三种常用抛光方法的比较，发现电抛光处理过的试样表面最平整，自腐蚀电流密度最小，耐蚀性能显著提高。在硫酸、磷酸等电解液中的不同电压下对钛阳极氧化，通过测试氧化膜的着色与膜厚、极化曲线、交流阻抗和 Mott-Schottky 曲线
4、等，对钛阳极氧化膜的物理性能和它在模拟海水中的腐蚀行为进行研究。结果表明氧化膜颜色和膜厚随着电压升高而变化，耐蚀性能随着电压升高变化不大。与空白试样相比，阳极氧化后的试样耐蚀性能显著提高，其中基于磷酸工艺的钛阳极氧化膜在低频区阻抗更大，载流子密度更大，平带点位更负，与硫酸工艺相比体现了优越性。以 8:1 的面积比将钛与碳钢偶接，通过电偶电流测试了其在模拟海水中 8 小时的电偶腐蚀情况。结果表明，钛与碳钢的电偶电流密度为 175A 左右；在磷酸和硫酸中阳极氧化后的钛片与碳钢的电偶电流显著降低，磷酸工艺电压为 40V 时电偶电流接近40A，硫酸工艺电压为 40V 时电偶电流接近 80A；钛阳极氧化
5、膜在整个电偶反应的体系中相当于额外的电阻极化。 采用极化曲线和交流阻抗法考察了阳极氧化对钛在高温含溴醋酸中的腐蚀行为的影响。结果表明，钛空白试样的点蚀破裂电位为 1750mV，阳极氧化后的钛片自腐蚀电位上升，自腐蚀电流密度下降，耐蚀性能显著提高，无点蚀现象发生。在硫酸铵、硫酸和磷酸溶液中对钛阳极氧化，均可以提高其在高温含溴醋酸介质中的耐蚀性能。关键词：钛；电化学抛光；阳极氧化；腐蚀行为钛 电 化 学 抛 光 及 其 阳 极 氧 化 膜 的 腐 蚀 行 为 研 究- II -Research on Electropolishing and Corrosion Behavior of Anodiz
6、ed TitaniumAbstractElectropolishing and anodizing are both important surface technologies for titanium. The former is always used in pretreatment for metal. The anodizing has a good prospect of application in aviation, medical, military, et al. With the research of anodizing being more widely, it is
7、 an unpreventable trend used in ocean engineering and chemical industry. In this paper, a new friendly environmental electropolishing technology was proposed. Moreover, anodizing of titanium in H3PO4 and H2SO4 was implement. The corrosion behavior of titanium and after anodizing were studied in 3.5w
8、t% NaCl solution and Br- containing CH3COOH solution, which is meaningful for practical use. In this paper, Cl- containing ethylene glycol was used for electropolishing titanium. Surface brightness and roughness were main standard used for study the condition. The optimal condition was 30V, 180s, 50
9、 and 2cm. In this condition, the surface of titanium was mirror like and the roughness was 0.090.02m. Whats more, we compared the mechanical polishing, chemical polishing and electropolishing by SEM and corrosion resistance tests. The results showed that titanium after electropolishing got more smoo
10、th surface and better corrosion resistance, which had lower icorr.Different voltage anodizing in H3PO4 and H2SO4 for titanium were conducted. Physical performance and corrosion behavior of the anodic oxide films in modified seawater were investigated by the color and thickness, potentiodynamic polar
11、ization curve, EIS and Mott-Schottky plots. It was found that the color and thickness of the film were changed with the voltage except the corrosion behavior. Compared with the blank sample, the corrosion resistance were improved largely when titanium after anodizing. EIS exhibit higher impedence va
12、lues in the low frequency range for films anodized in phosphoric acid. Meanwhile the Mott-Schottky plot indicate lower donor density and lower flat band potential for titanium anodized in H3PO4, which reflected better property than in H2SO4.The galvanic corrosion generated between the titanium-carbo
13、n steel pair in area ratio at 8:1 for 8 hours has been studied in modified seawater. The results showed that galvanic current densities was 175A before titanium anodizing. It became more lower when titanium anodizing in H3PO4 or H2SO4. Moreover, we found that 40V was a good voltage for both technolo
14、gy. Galvanic current densitity was 40A for H3PO4 and 80A for H2SO4. The anodic oxide films lead to an IR drop in the system.大 连 理 工 大 学 硕 士 学 位 论 文- III -The corrosion behavior of titanium after anodizing was investigated by potentiodynamic polarization curve, EIS in Br- containing acetic acid solut
15、ion. The breakdown potential of the pitting is 1750mV for blank sample. Titanium after anodizing showed higher self-corrosion potential, lower icorr, thus the better corrosion resistance. And the breakdown potential of titanium after anodizing was not found. In sum, titanium after anodizing in (NH4)2SO4, H2SO4 and H3PO4 are all good ways for improving corrosion resistance in Br- containing acetic acid solution.Key Words：Titanium; Electropolishing; Anodic Oxide; Corrosion Behavior钛 电 化 学 抛 光 及 其 阳 极 氧 化
