钢筋混凝土Cl~-离子检测传感器的制备与性能研究

发布时间：2018-09-10 09:29

【摘要】：氯盐是引起钢筋混凝土结构腐蚀的最主要因素,因此准确检测其内氯离子浓度具有重要的意义。传统的取样检测方法对混凝土结构本身产生损坏,且工作量大、操作繁琐,而埋入式氯离子传感器因电极寿命短、抗污染能力差也受到限制。本文以银箔为基体制备了卷压式Ag/AgCl电极,同时采用热压法制备了粉压型Ag/AgCl电极以及粉压型MnO2参比电极。实验结果表明,电极具有较好的电化学响应特性曲线,适用于混凝土内氯离子含量的检测。本文首先通过恒电流氧化法制备了卷压式Ag/AgCl电极,并测试了其在模拟孔溶液中的响应,电极在溶液中浸泡230d内电位波动小于6mV,具有较接近理论值的线性响应斜率,且腐蚀电流密度大,具有一定的抗污染能力。SEM形貌分析表明:卷压方式不仅增加了电极的活性比表面积,提高电极的稳定性与反应活性;同时,借助AgCl/Ag的多层堆叠,增强了颗粒与基体间的附着力,提高Cl-离子检测的可靠性及电极使用寿命。其次,对混凝土半透膜、碱性凝胶电解质、锰环体三部分进行了电化学测试并组装制备MnO2参比电极。结果显示,β-MnO2电化学活性更高,自制凝胶电解质的保水性和导电性良好,采用膨胀剂制备的混凝土半透膜电阻最小,MnO2电极埋置于混凝土中稳定性良好,有一定的抗极化能力。本文还将卷压式Ag/AgCl电极表面包裹含聚乙烯醇凝胶电解质的无纺布,并将其埋置于混凝土中,其养护龄期内电位稳定性良好,电位与Log[Cl-]呈较好的线性度。在内掺低浓度的硫离子及胺类缓蚀剂情况下,电位漂移不大,表明其抗干扰能力强。与化学分析法相比,卷压式电极所检测的氯离子浓度偏小,但可通过误差系数修正。本文最后还采用碳纳米管(CNTs)与Ag/AgCl制备了碳基复合电极传感器,发现Ag/AgCl/CNTs在溶液浸泡60d内电位稳定性依然较好,其线性响应斜率为49.91mV,且具有较小的电荷传递电阻及较大的腐蚀电流密度,是一种有希望的混凝土Cl-浓度监测传感器。
[Abstract]:Chloride salt is the most important factor to cause corrosion of reinforced concrete structure, so it is very important to accurately detect the concentration of chloride ion in reinforced concrete structure. The traditional sampling and detection methods have caused damage to the concrete structure itself, and the workload is large and the operation is cumbersome. However, because of the short electrode life, the poor anti-pollution ability of the embedded chlorine ion sensor is also limited. In this paper, the rolled Ag/AgCl electrode was prepared with silver foil as the substrate, and the powder pressed Ag/AgCl electrode and the powdered MnO2 reference electrode were prepared by hot pressing method. The experimental results show that the electrode has a good electrochemical response curve and is suitable for the detection of chloride ion content in concrete. In this paper, the coil type Ag/AgCl electrode was prepared by constant current oxidation method, and its response in simulated pore solution was measured. The potential fluctuation was less than 6 MV within 230 days after immersion in the solution, which showed a linear response slope close to the theoretical value. Moreover, the corrosion current density is high, and it has some anti-pollution ability. SEM morphology analysis shows that the coiling method not only increases the specific surface area of the electrode, but also improves the stability and reaction activity of the electrode, at the same time, with the help of the multilayer stacking of AgCl/Ag, The adhesion between particles and matrix was enhanced, and the reliability of Cl- ion detection and the lifetime of electrode were improved. Secondly, the MnO2 reference electrode was prepared by electrochemical measurement on the three parts of semi-permeable concrete membrane, alkaline gel electrolyte and manganese ring. The results show that the electrochemical activity of 尾 -MnO2 is higher, the water retention and electrical conductivity of self-made gel electrolyte are good, and the semi-permeable film resistance of concrete prepared with dilatant has good stability and polarization resistance. In this paper, the non-woven fabric containing polyvinyl alcohol gel electrolyte is coated on the surface of the rolled Ag/AgCl electrode and buried in concrete. The potential has good stability during curing period, and the potential has a good linearity with Log [Cl-]. Under the condition of low concentration of sulfur ion and amine inhibitor, the potential drift is small, which indicates that its anti-interference ability is strong. Compared with the chemical analysis method, the chloride concentration detected by the coil electrode is smaller, but can be corrected by error coefficient. Finally, carbon nanotube (CNTs) and Ag/AgCl were used to fabricate the carbon based composite electrode sensor. It was found that the potential stability of Ag/AgCl/CNTs was still good within 60 days of immersion in solution. Its linear response slope is 49.91mV, and it has smaller charge transfer resistance and larger corrosion current density. It is a promising concrete Cl- concentration monitoring sensor.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU375;TP212

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