【作者】 苗燕；

【导师】 张胜涛； 候保荣；

【作者基本信息】 重庆大学 ， 应用化学， 2003， 硕士

【摘要】 在海洋工业中，存在许多的金属结构，它们的腐蚀程度检测是安全检测的重要内容之一。在海洋金属结构的阴极保护系统中，需要对多种电化学参数进行测量，而精度高、稳定性强的参比电极是进行电化学测量的重要部件之一。由于海水中的压差变化大等特性以及海洋环境的复杂性，目前，在进行电化学测试时银/氯化银电极被公认为海水中最为理想的参比电极。但是，市售的银/氯化银参比电极并不适用于阴极保护系统，也不能长期在海水中使用。本论文针对目前使用参比电极存在的不耐高压、长期稳定性差、精度低等问题，并结合深海高压使用环境的具体特点，研制了全固态的银/氯化银参比电极，并对电极的性能进行了测试，证明了本论文所研制的银/氯化银电极具有耐高压、稳定性好、精度高等特性。采用粉末压片法制备的银/氯化银参比电极满足了深海高压环境的使用要求。参比电极的主体部分由纯银粉和自制的氯化银粉末按一定的比例混合均匀后，在粉末压片机上高压压制而成，实验结果证明，在1～10吨/厘米2的压力范围内，压制压力对参比电极性能没有明显的影响，因此，为了简化电极制备工艺和防止电极在深海高压环境下脱粉，选用了较高的压制压力10吨/厘米2。当氯化银粉末含量小于20％时，银粉含量过大，构成了银电极和银/氯化银电极的混合电极，电位差别较大；当氯化银粉末含量大于70％时，氯化银粉末含量过大，电极不导通，无法测量电极电位；当氯化银粉末含量在20％～70％之间时，电极性能没有明显的差别。采用室温固相法自制的氯化银粉末，通过扫描电子显微镜观察，其粒径在2～3微米左右，这种细小氯化银粉末的使用有利于增加电极表面的活性中心，有利于提高参比电极的电化学性能。研制成型的银/氯化银参比电极在海水中具有良好的长期稳定性、Nernst响应特性和温度响应特性，长期海水浸泡电极电位漂移为±0.5mV。由于海水中含有多种离子，所以本论文还针对所制备电极的具体应用环境研究了干扰离子，如Br－，SO42－等，对参比电极电位的影响，结果表明Br－的存在会使电极表面形成氯化银和溴化银的固溶体，使电极电位变小，但是并不影响电极电位的稳定性；SO42－不会明显影响参比电极的电极电位。同时，通过模拟水流实验装置模拟了参比电极在实际使用过程中受水流流动的影响情况，研究了海水流速与参比电极电位的关系，结果表明，当水流速度小于5m/s时，电极电位几乎不受影响。此外，还采用了电化学阻抗谱技术，对电极的动力学参数进行了测量，对比了不同情况下的电极表面状态，结果表明本文所研制的银/氯化银电极具有较小的极化电阻，并具有良好的可逆电极过程的特征。<WP=5>本论文所研制的银/氯化银全固态参比电极已经申请了发明专利，专利申请号为03138856.6；同时制作电极的模具也已申请了实用新型专利，专利申请号为03271344.4。本论文所研制的银/氯化银全固态参比电极最终将被应用于国家863课题的“不接触测量阴极保护电位技术”，制作成腐蚀检测探头，应用于海底管线的腐蚀监测。更多还原

【Abstract】 In the industry of marine exploration, there are many subsea metal structures. Corrosion monitoring is the most important of safety monitoring. In cathodic protector system for subsea metal structures, measuring electrical chemistry parameters is needed. It is necessary to have a reference electrode that is exact and stability. Due to the changes of pressure and the complicate properties of marine environment, nowadays, Ag/AgCl reference electrode often is used in electrical chemistry measurement, which is regarded as the best reference electrode. However, the Ag/AgCl reference electrode bought from market cannot be used for cathodic protector system and marine environment for a long time. In this paper, in order to deal with the problems of reference electrode used now, a Ag/AgCl all-solid-state reference electrode was studied, according to the conditions of deep marine environment. The results show that the reference electrode studied is characteristic of precision, stability, and enduring high pressure.In order to endure the high-pressure of deep marine, the reference electrode was made by using Press Powder Method. The main part of reference electrode composed of pure silver powder and silver chloride powder was made by high pressure. The effect of the pressure of pressing the electrode was studied, the result of which shows that when the pressure is between 1T/cm2 and 10T/cm2, it did not effect the properties of electrode. But in order to simplify the manufacture and endure the high-pressure, high pressing pressure, 10T/cm2, was chosen. When the percent content of AgCl is less than 20%, masses of Ag bring on quite difference of electrical potential. When the percent content of AgCl is more than 70%, superfluous AgCl did not conduct electricity. When the percent content of AgCl is between 20% and 70%, the properties of electrode had not changes obviously. Silver chloride powder was made by solid-phase reactions at room temperature. Their structure and particle size were characterized with SEM. It was found that the particle size is 2～3μm. The very small powder can increase the active center of electrode surface and enhance the electrical chemistry properties of reference electrode. Ag/AgCl all-solid-state reference electrode studied had good properties such as long stability in seawater, Nernst response property, temperature response property and antipolarization. Electrode potential drifts±0.5mV for long time test. Because there are many ions in seawater, the effect of these ions to electrode<WP=7>potential must be studied. The result shows that Br－ can make the electrode potential decrease and still remains stable for a long time, and SO42－ cannot affect the electrode potential apparently. At the same time, according to simulate the real conditions of using the reference electrode in marine, the relationship between velocity and electrode potential was studied by using the analog testing equipment. Additionally, The result shows that the influence of seawater flow on the electrode potential is slight when the velocity is less than 5m/s. The simple kinetics parameters of reference electrode were measured by using Electrochemical Impedance Spectroscopy (EIS). The result shows that the reference electrode is characteristic of reversible electrode.Ag/AgCl all-solid-state reference electrode studied has applied for invention patent, and the number is 03138856.6. At the same time, the mould that making electrode has applied for applied new type patent, the number is 03271344.4. Ag/AgCl all-solid-state reference electrode studied will be applied in 863 project, the technique of detecting cathodic protection potential without touch. It will be made into the probe for corrosion monitoring and be used to monitor the corrosion potential of seabed pipes.更多还原