模拟混凝土孔隙液中几种有机缓蚀剂在碳钢表面吸附及缓蚀行为研究

发布时间：2018-05-26 00:24

本文选题：碳钢 + 缓蚀剂　；参考：《北京化工大学》2016年博士论文

【摘要】：钢筋混凝土是当前世界上使用最广泛、用量最大的建筑工程结构材料,混凝土中钢筋的腐蚀破坏是混凝土结构件失效的主要原因之一。添加缓蚀剂是一种较为有效的抑制钢筋腐蚀破坏的手段,但目前钢筋混凝土体系中,能够同时抑制均匀腐蚀及局部腐蚀的缓蚀剂多为亚硝酸盐等无机缓蚀剂,这类缓蚀剂往往具有一定的毒性。而较为绿色环保的有机缓蚀剂由于作用机制复杂、对局部腐蚀抑制行为较难观测,研究相对较少。对均匀腐蚀及局部腐蚀具有良好抑制作用的有机缓蚀剂亟待研究。为克服传统电化学方法对缓蚀剂界面作用行为观测困难等问题,将光谱系统与电化学测试、分子模拟连用研究腐蚀行为细节、缓蚀剂的作用机制是当前研究的热点。本论文的研究对象是丁二酰亚胺(SI)、L-脯氨酸(LP)、木质素磺酸钙(CLS)、羧甲基纤维素钠(CMC)及油酸钠(SO)五种有机分子；本论文的主要内容是研究这五种缓蚀剂对Q235碳钢在模拟钢筋混凝土孔隙液中的吸附行为及缓蚀机理。在进行研究之前,我们首先对五种有机分子的化学结构进行表征,并探索了一种适用于检测有机缓蚀剂在碳钢表面对局部腐蚀作用行为的体系,即,pH值12.5含0.1 mol/L NaCl的饱和Ca(OH)2溶液作为模拟钢筋混凝土孔隙液(SCP溶液)。本论文的研究成果主要分如下几个方面：(1) 通过进行静态失重实验、动电位极化曲线慢扫、SEM-EDS及XPS测试研究了丁二酰亚胺(SI)、L-脯氨酸(LP)、木质素磺酸钙(CLS)、羧甲基纤维素钠(CMC)及油酸钠(SO)五种缓蚀剂对碳钢在SCP溶液中的缓蚀行为,研究表明,缓蚀剂对碳钢腐蚀的抑制作用由大到小依次为CLSSOCMCSILP。其中,CLS对碳钢在SCP溶液中的均匀腐蚀及局部腐蚀均有良好的缓蚀作用,在添加量为0.001 mol/L时,静态失重测得缓蚀率达到98%以上,极化曲线钝化区范围约960 mV, CLS对小孔腐蚀有较强的抑制作用。SO和CMC的缓蚀率在添加量为0.0008 mol/L时分别为77%及61%。SI及LP对碳钢在SCP溶液中不具有缓蚀性能,添加LP后,伴随缓蚀剂浓度增加,试样表面腐蚀反而加速。(2) 对CLS及SO对碳钢在SCP溶液中的缓蚀机理进行了研究,结果表明,CLS分子中的-S03基团能够与钝化膜上富集的Ca发生吸附,形成"Ca-O-S共吸附”结构,是一种物理吸附,其苯环基团能够形成离域的π键与界面Fe的3d空轨道配位,形成化学吸附。CLS既有化学吸附又有物理吸附,与界面结合吸附能较高,形成的膜层较为致密、牢固,因此对均匀腐蚀和局部腐蚀抑制良好。SO分子溶于水后带有负电荷,会自发向在SCP溶液中带有正电荷的碳钢表面扩散,极性的羧基吸附在碳钢表面,而非极性的长碳链向碳钢外部排布,在钝化膜的表面形成了一层新的阻隔层,对溶液中CI-离子有一定的阻隔作用,显著地降低了试样表面C1元素含量,该缓蚀机理得到有机分子在金属／溶液界面吸附机理的支持。(3) 采用荧光显微镜观测了在未添加及添加了五种有机缓蚀剂的SCP溶液中浸泡10h后试样表面膜层的结构,通过观测添加不同缓蚀剂后试样表面在荧光显微镜下发出荧光颜色及强弱,验证了有机缓蚀剂在钝化体系中“吸附膜-钝化膜-基体”的双层膜结构。(4)通过测定试样在分别添加五种缓蚀剂的SCP溶液中浸泡7200 h的长期静态失重实验,研究了五种缓蚀剂的长期缓蚀性能,其缓蚀率从高到底依次为CLSSOCMCSILP,整体趋势与720 h失重实验结果一致。SI、LP及CMC在长期失重实验中失去缓蚀效果,SO仅在添加量高于0.0008 mol/L时缓蚀率超过75%。CLS在低浓度也具有一定的缓蚀效率,添加量为0.0002 mol/L时,缓蚀率为75%,添加量在0.0008 mol/L以上时,缓蚀率大于93%,是一种适用于长期使用的有机缓蚀剂。(5)首次采用了显微红外成像系统对添加缓蚀剂SCP溶液浸泡10h后试样表面进行显微红外成像观测,研究了五种缓蚀剂在碳钢表面的吸附行为。并首次通过官能团分布图测试观测到了CLS中的紫丁香基团对小孔的特性吸附,CLS的特性吸附得到软硬酸碱理论的支持。(6)通过对五种缓蚀剂的量子化学参数进行计算,根据缓蚀剂构效研究规律,对其缓蚀性能进行初步的预测,计算结果表明,五种缓蚀剂的缓蚀性能应为SOCLSCMCLPSI,但根据失重及极化曲线数据研究表明五种缓蚀剂的能力依次为CLSSOCMCSILP。研究表明,在AE差别不大时,有机缓蚀剂的特性吸附对其缓蚀性能有一定的影响。量子化学计算更适用于均匀吸附、具有较为类似结构或AE相差较大的缓蚀剂分子的缓蚀性能预测。
[Abstract]:Reinforced concrete is the most widely used and most widely used construction material in the world. Corrosion damage of reinforced concrete in concrete is one of the main reasons for failure of concrete structures. Adding corrosion inhibitor is a more effective means to suppress corrosion and damage of steel bars, but at present, the reinforced concrete system can suppress both at the same time. The corrosion inhibitors of uniform corrosion and local corrosion are most of the inorganic inhibitors such as nitrite. These inhibitors often have certain toxicity, and the more green and environmentally friendly corrosion inhibitors are difficult to observe the local corrosion inhibition behavior because of the complex mechanism of action, and have a relatively small study on the uniform corrosion and local corrosion. In order to overcome the difficulty in observing the interfacial action of corrosion inhibitors by traditional electrochemical methods, the spectroscopic system, electrochemical testing and molecular simulation are used to study the details of corrosion behavior. The mechanism of corrosion inhibitors is the hot spot of current research. The research object of this paper is SI (SI), L- proline (LP), wood Calcium sulfonate (CLS), carboxymethyl cellulose sodium (CMC) and sodium oleate (SO) are five organic molecules. The main content of this paper is to study the adsorption behavior and corrosion inhibition mechanism of the five inhibitors on the simulated reinforced concrete pore fluid. Before the study, we first characterize the chemical structures of the five organic molecules. A system for detecting the local corrosion behavior of organic corrosion inhibitors on the surface of carbon steel is also explored, that is, the saturated Ca (OH) 2 solution of pH value 12.5 containing 0.1 mol/L NaCl is used as a simulated reinforced concrete pore fluid (SCP solution). The research results of this paper are mainly divided into the following aspects: (1) the static weight loss experiment and the dynamic potential are carried out. The slow sweep of polarization curves, SEM-EDS and XPS tests have been carried out to study the corrosion inhibition behavior of the five inhibitors of succinimide (SI), L- proline (LP), calcium lignosulfonate (CLS), sodium carboxymethyl cellulose sodium (CMC) and sodium oleate (SO) on the carbon steel in SCP solution. The study shows that the inhibition effect of corrosion inhibitor on carbon steel corrosion from large to small is in the order of CLSSOCMCSILP. and CL. S has a good corrosion inhibition effect on the uniform corrosion and local corrosion of carbon steel in SCP solution. The corrosion inhibition rate of static weightlessness is above 98% when the addition amount is 0.001 mol/L, the polarization curve passivation area is about 960 mV, CLS has a strong inhibition effect on the micropore corrosion.SO and CMC, and the corrosion inhibition rate of.SO and CMC is 77%, respectively, when the addition amount is 0.0008 mol/L. And 61%.SI and LP have no corrosion inhibition in SCP solution. After adding LP, the corrosion of the specimen is accelerated with the increase of corrosion inhibitor concentration. (2) the corrosion inhibition mechanism of CLS and SO in SCP solution is studied. The results show that the -S03 group in CLS molecules can be adsorbed to Ca enriched on the passivation film, forming a "Ca-O-S". The CO adsorption structure is a physical adsorption. The benzene ring group can form the off domain pi bond and the 3D empty orbit of the interface Fe. The chemical adsorption.CLS has both chemical adsorption and physical adsorption, and the adsorption energy of the interface is higher and the formation of the membrane is more compact and solid, so it is good for the.SO molecular solution to inhibit the uniform corrosion and local corrosion. With negative charge after water, it will spontaneously spread to the surface of carbon steel with positive charge in SCP solution, the polar carboxyl group is adsorbed on the surface of carbon steel, and the non polar long carbon chain is arranged outside the carbon steel. A new barrier layer is formed on the surface of the passivation film, which has a certain barrier effect on the CI- ion in the solution, which significantly reduces the sample sheet. The C1 element content of the surface is supported by the mechanism of the adsorption of organic molecules at the metal / solution interface. (3) the structure of the surface film layer of the sample was observed after 10h immersion in the SCP solution without adding and adding five kinds of organic inhibitors. The surface of the sample was observed by the fluorescence microscope after adding different inhibitors. Under the fluorescence color and strength, the double layer membrane structure of the "adsorption film passivation film matrix" in the passivation system was verified. (4) the long-term static weight loss test of 7200 h was soaked in the SCP solution with five inhibitors respectively. The corrosion inhibition rate of the corrosion inhibitor was studied. The whole trend is CLSSOCMCSILP in turn, and the overall trend is consistent with the results of 720 h weightlessness test. LP and CMC lose the inhibition effect in the long-term weightlessness test. SO only has a certain corrosion inhibition efficiency when the addition amount is higher than that of 0.0008 mol/L and has a certain corrosion inhibition efficiency at lower concentration than 75%.CLS. The corrosion inhibition rate is 75% and the addition amount is 0.0008 mol/L when the addition amount is 0.0002 mol/L. At the same time, the corrosion inhibition rate is more than 93%, and it is an organic corrosion inhibitor for long-term use. (5) the microinfrared imaging system was first used to observe the surface of the sample surface after the corrosion inhibitor SCP solution was soaked for 10h. The absorption behavior of five inhibitors on the surface of carbon steel was studied. The lilac group in CLS adsorbed the pore characteristics and the properties of CLS adsorbed the support of the theory of soft and hard acid and alkali. (6) by calculating the quantum chemical parameters of the five inhibitors, the corrosion inhibition performance was preliminarily predicted according to the research law of the corrosion inhibitor, and the results showed that the corrosion inhibition of the five inhibitors should be SO. CLSCMCLPSI, however, according to the data of weight loss and polarization curve, the ability of the five inhibitors is CLSSOCMCSILP. study in turn. The adsorption of organic inhibitors has a certain effect on its corrosion inhibition when the difference of AE is not large. Quantum chemical calculation is more suitable for uniform adsorption, and has a relatively similar structure or a relatively large difference in corrosion inhibition of AE. Anticorrosion performance prediction of agent molecules.
【学位授予单位】：北京化工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG174.42

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