【作者】 胡捷；

【导师】 甘复兴；

【作者基本信息】 武汉大学 ， 环境工程， 2009， 博士

【摘要】 电偶效应是两种不同的金属或非金属导体在电解质溶液中接触时普遍存在的现象：当异种导体在同一电解质中接触时,较低电位的导体中的电子就要向高电位导体流动。与此同时,在电位较低的阳极导体表面发生氧化反应,在电位较高的阴极金属表面发生还原反应。具体到腐蚀领域,电偶效应对金属的腐蚀会造成很大的影响,另一方面,也能应用电偶效应为金属腐蚀提供保护作用。因此,本文在国家自然科学基金和美国环保总局(US EPA)的资助下,分别对美国饮用水管道体系中铜管和铅管间的电偶腐蚀效应以及导电高分子材料对不锈钢的伽伐尼电偶保护效应这两种新的电偶效应进行了系统的研究。在美国饮用水管道体系中铜管和铅管间的电偶腐蚀效应研究中,通过设计完善的铅管与铜管电偶腐蚀的研究实验方案,采用直接测量水样中铅浓度结合电化学测试的方法,对铅管的电偶腐蚀效应以及含铜饮用水对铅管的微电偶蚀效应进行了系统的探讨。主要的工作和结论如下：(1)当新铅管与铜管电化学偶合时,铅管的电偶腐蚀会引起饮用水中铅含量的急剧增加；当老铅管与铜管电化学偶合时,在偶合初期,由于偶合会使得老铅管表明的氧化物膜更加稳定,从而使得饮用水中铅含量比没有偶合时要低。但随着时间的推移,铅管的电偶腐蚀效应将成为饮用水中铅的主要来源,从而引起饮用水中铅含量的上升。(2)饮用水中的Cl-与S042+的质量比(CSMR)是影响铅管电偶腐蚀的重要因素：CSMR越高,铅管的腐蚀速度越快。消毒剂的选择也会对铅管的电偶腐蚀产生影响,当选择NH4Cl作为消毒剂时,铅管的腐蚀速度较快。但是与CSMR相比,消毒剂对铅管电偶腐蚀的影响相对比较小。(3)饮用水管道中铅管的“局部替换”不能解决由于消毒剂从NaClO更换为NH4Cl所带来的铅腐蚀问题,反而会由于铅管的电偶腐蚀效应使得这一问题更加严重。(4)在静止停滞状态下,饮用水中的Cu2+的沉积会对铅管造成微电偶腐蚀效应。微电偶腐蚀在一段时间内会引起饮用水中铅浓度的上升；在流动状态下,饮用水中的Cu2+同样会对铅管造成微电偶腐蚀,从而引起饮用水中铅浓度的上升。此外,在流动状态下,铅管的微电偶腐蚀速度更快,腐蚀强度更大。(5)在静止停滞状态下,低浓度的含铜水样同样会引起铅管的微电偶腐蚀,从而在一段时期内引起水样中总铅浓度的上升。这一点对于饮用水管道体系中微电偶腐蚀的实际控制具有很重要的指导意义。在导电高分子材料对不锈钢的伽伐尼电偶保护效应的研究中,在以前研究的基础上,采用不同的聚合方法制备出了单独的聚吡咯(PPy)电极,比较系统的研究了PPy电极的电化学行为；采用PPy电极与不锈钢电极电化学偶合的方法研究了PPy对不锈钢的“伽伐尼阳极电偶保护效应”的应用,同时对PPy和PANi这两种高分子材料提供的“伽伐尼阳极保护效应”进行了详细的对比。主要的工作和结论如下：(1)研究了聚合介质中氧化剂的种类、氧化剂与吡咯单体的摩尔比及反应时间、反应温度对化学氧化法合成产物的影响,确定最佳的聚合条件为：以FeCl3作为氧化剂,0.5M吡咯单体+2M HClO4,FeCl3和吡咯单体的摩尔比为1：1,反应时间为3h,反应温度为0-4℃。(2)PPy粉末压片电极在不同的条件下均能对410不锈钢提供高效的伽伐尼阳极电偶保护,PPy对不锈钢的伽伐尼阳极电偶保护效应受阴阳极(PPy/不锈钢)面积比、酸浓度、溶液酸性强弱的影响：PPy/不锈钢面积比越大,不锈钢的钝态越稳定；酸浓度越大、溶液酸性越强则使不锈钢长期稳定钝化所需的阴阳极面积比越大。(3)除410不锈钢外,PPy粉末压片电极对其他铁基金属也能提供高效的伽伐尼阳极保护效应,如304、316和321不锈钢、碳钢等。聚吡咯伽伐尼阳极保护对可钝铁基金属均适用。(4)对于不锈钢在酸性介质中的防腐,聚吡咯要优于聚苯胺,它的保护效率更高、提供保护的时间更长,而且能够在更加苛刻的条件下提供伽伐尼阳极保护。然而,与聚吡咯相比,聚苯胺更加适合应用于不锈钢点蚀的腐蚀防护。更多还原

【Abstract】 Ganlvanic effect is a common phenomenon which will exist when two different metals contact together in solution:when two different metals contact with each other in the solution, the electron will transport from the metal with low potential to the metal with high potential. In the meanwhile, the oxidation reaction will take place on the surface of the anodic metal with low potential and the reduction reaction will take place on the surface of the cathodic metal with high potential. Focused on the corrosion field, on one hand, the galvanic effect can cause important influence to the corrosion of the metal; on the other hand, it can be also applied to provide corrosion protection to the metal. Therefore, in this work, which is supported by the national science foundation of China and US Environmental Agency, the galvanic effect between the lead pipe and copper pipe in US drinking water distribution system and the galvanic anodic protection of the stainless steel by conductive polymer were systematically studied respectively.In the research on the galvanic effect between the lead pipe and copper pipe in US drinking water distribution system, the experiment plan was well deisned. The galvanic corrosion of the lead pipe and the deposition corrosion caused by the Cu2+in the drinking water were studied by directly measuring the lead concentration in the water combined with the electrochemical measurement. The main work and results are as follows:(1) When the new lead pipe was galvanically connected with copper pipe, the lead amount in the drinking water increased which was resulted from the galvanic corrosion of the lead pipe; when the old pipe was galvanically connected with copper pipe, at the start of the connection, the lead amount in the drinking water decreased becaue the connection made the lead oxidate film on the lead pipe more stable. However, as the connection continued, the galvanic corrosion of the lead pipe became the main resource of the lead in the drinking water and caused the in creased of the lead amount in the drinking water.(2) The CSMR of the drinking water is an important factor which can influence the galvanic corrosion of the lead pipe:the higher the CSMR is, the higher the corrosion rate of the lead pipe is. The disinfectant choice can also influence the galvanic corrosion of the lead pipe. When NH4Cl is chosen as the disinfectant, the corrosion rate of the lead pipe is faster. However, compared with CSMR, the influence of the disinfectan is not so obvious.(3) The "partial replacement" of the lead pipe in the US drinking water system can not solve the "lead crisis" caused by the disinfectant swith from free chlorine to chloramine. Furthermore, it will make the problem even worse because of the galvanic corrosion of the lead pipe.(4) In the stagnant condition, the Cu2+ in the drinking water caused deposition corrosion to the lead pipe. The deposition corrosion resulted in the increase of the lead concentration in the drinking water in a certain period. In the flowing condition, the Cu2+ in the drinking water caused deposition corrosion to the lead pipe and resulted in the increase of the lead concentration in the drinking water. Furthermore, in the flowing condition, the rate of the deposition corrosion was faster.(5) In the stagnant condition, the drinking water with a low Cu2+concentration still caused deposition corrosion to the lead pipe and resulted in the increase of the lead concentration in the drinking water. This point is very important to the actual deposition corrosion control in the drinking distribution pipe systemIn the research on the galvanic anodic protection of the stainless steel by conductive polymer, based on our formal research, the separate PPy powder-pressed electrodes have been prepared and the electrochemical properties of the PPy electrode were studied. The galvanic anodic protection of the stainless steel was studied by the means of galvanically coupling the PPy electrode and stainless steel. The galvanic anodic protection provided by PPy and PANi were compared. The results are as follows: (1) The influences of many factors on PPy’s electro-synthesis were studied, such as the kind and concentration of oxidant in the synthesis solution, the mol ratio of oxidant to aniline monomer, reaction temperature and reaction time. The best synthesized conditions were as follows:the FeCl3 was adopted as the oxidant, the solution is 0.5M pyrrole and 2M HClO4, the mol ratio of FeCl3 to pyrrole is 1:1, the reaction temperature is 0～4℃, and the reaction time is 3h.(2) PPy powder-pressed electrode can provide efficient galvanic anodic protection to 410 stainless steel under different conditions. The protection is influenced by many factors such as the area ratio of PPy to 410 stainless steel, the concentration of the acid and the solution acidity. The larger the area ratio of PPy to 410 stainless steel is, the more stable the passivity of the stainless steel is. More PPy will be needed when the acid concentration is higher and the solution aicidity is higher.(3) Besides 410 stainless steel, PPy powder-pressed electrode can also provide galvanic anodic protection to other ferrous metals, such as 304 stainless steel,316 stainless steel,321 stainless steel, carbon steel and so on.(4) For the galvanic anodic protection of stainless steel, PPy is better than PANi. It is more efficient and can protect the stainless steel for a longer time and in a stronger acid solution. However, for the pitting corrosion protection of stainless steel, PANi is better than PPy.更多还原