【作者】 王淑慧；

【导师】 彭乔；

【作者基本信息】 大连理工大学 ， 化学工程， 2010， 硕士

【摘要】 随着工业的飞速发展,地下金属构件的腐蚀与保护得到进一步重视。阴极保护作为最经济有效的方法被广泛的采用。钛基金属氧化物电极作为外加电流阴极保护用辅助阳极材料的研究与开发也变得尤为重要。本文采用传统的热分解法,通过正交试验设计研究了铱钴涂层钛电极的制备工艺对电极电化学性能的影响。采用SEM、EDX、EPMA、XRD等检测手段对所制备电极的微观形貌、元素组成和分布、涂层结构等进行分析,同时采用动电位扫描、循环伏安和交流阻抗测试技术研究电极的电化学性能。对电极的失效行为进行了分析。以所制备的优良电极为阳极,研究其在土壤中的电化学行为,并比较了在土壤中与硫酸溶液中的电化学性能。涂层的制备工艺主要包括金属离子浓度,组元配比,热氧化温度,涂刷次数,以析氧电位,析氧电流,伏安电荷量等为主要指标,对以上制备条件进行优化,确定了最佳制备工艺参数为：涂液浓度0.2 mol／L,热氧化温度450℃,铱钴物质的量之比为2：1,涂刷次数以最终覆盖量达到1.0g／cm2为止。结果表明这些因素对Ir-Co/Ti电极表面形貌及电化学性能影响的顺序依次是热氧化温度、金属离子总浓度、Ir:Co物质的量之比、涂刷次数。随着热氧化温度的升高,电极表面裂纹的数目增多,裂纹的深度增加。当金属离子浓度较大时容易出现挂液现象,导致电极不容易涂匀；而如果金属离子浓度较小,单次涂刷的涂敷量较小,需要增大涂刷次数,延长电极的制备时间。Ir:Co物质的量之比对电极的催化性能影响较大,Co的添加可以增大电极的真实表面积,但是当Co的添加量超过一定数值后电极的催化性能降低,电极的寿命也缩短。对涂刷制度进行了研究,结果表明,在不同的涂刷制度下电极的电化学性能有较大差异,最终确定电极的涂刷制度为先烘干三次后再烧结,重复一次后再进行烘干-烧结,既节省制备时间,电极性能又得到提高。强化电解试验表明Ir-Co/Ti电极失效的原因有两个：一是由于涂层溶解导致涂层脱落,二是在基体和涂层之间生成一层不导电的TiO2。对电极在土壤中的电化学行为的考察发现,随着含水量的增大,电极的催化性能先急剧增大,当土壤达到基本饱和以后,电极的催化性能基本不变,阻抗值在未达到饱和以前先急剧降低,然后基本不变,而离子扩散的难易程度也有较大差异。与在硫酸中相比较,电极的析氧机理基本相同,但是控制步骤不同。更多还原

【Abstract】 With the rapid development of industry, the corrosion and protection of underground metal components has been got further attention. The cathode protection as the most cost-effective method is widely used. The research and development of Ti-based metal oxide electrode as the impressed current cathodic protection with aid anode material have become particularly important.The thermal decomposition process is used to prepare Ir-Co/Ti anodes, and the effect of preparing technology parameter was investigated on the Ir-Co/Ti anodes in this paper. The microstructure, element compositions and distributions, phase compositions and structure of the Ir-Co/Ti anodes had been studied by means of scanning electron microscopy(SEM) with energy dispersive X-ray (EDX), electron probe microanalysis(EPMA), X-ray diffraction (XRD). And the electrochemical property was measured by anodic polarization curve, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). During this experiment, the deactivation mechanism was also explained. At last it was investigated that the best Ir-Co/Ti anodes’electrochemical behavior in soil with different water content, and compared with it in the H2SO4solution.Preparing technology parameter includes the metal ion’s concentration, the mole ratio of Ir and Co, the thermal oxidation temperature and the brushing times. Ir-Co/Ti anodes was optimized with the potential of oxygen evolution reaction (OER), the current density and the CV charge as the main assessing items and finally, the optimized process parameters were determined, which was as followed:the metal ion’s concentration0.2mol/L, thermal oxidation temperature 450℃, Ir:Co (mol)=2:1, the final surface covered by 1.0g/cm2. From the orthogonal test result it can be inferred that the factor’s order was the thermal oxidation temperature, the metal ion’s concentration, the mole ratio of Ir and Co, the brushing times. It can be seen the surface of the Ir-Co/Ti anodes had much crack, the number and the depth of it was larger as the thermal oxidation temperature rising. If the metal ion’s concentration is bigger, it is hard to brush evenly, but if it is smaller, the metal oxide covered with fewer amounts which indicated it needs more times to finish an electrode. As Co element added into the DSA, it can enlarge the true active area, but if its content is bigger than certain value, the function was becoming weaker. At the same time the service life of the Ir-Co/Ti anodes was shortened. The brushing procedure was investigated. It showed that electrochemical properties in different brushing system were quite different. The best brushing procedure was calcinated after the third solvent evaporated, repeat it again, then, calcinated once the solvent evaporated. The Accelerated Service Test (AST) result showed the reason of electrode deactivation was two mechanisms worked together. One is the coating pulled-off because of the coating unevenly dissolved. And the other is the formation of insulating TiO2-rich layer between coating and substrate.The electrocatalytic performance of the anode were improved at first and then keep steady with the water content increasing during the investigation Ir-Co/Ti anodes behavior in soil, so was the impedance value. The OER mechanism was similar in H2SO4 with in the soil, but the reaction determination step was different.更多还原