【作者】 张婷；

【导师】 龚敏；

【作者基本信息】 四川理工学院 ， 化学工艺， 2012， 硕士

【摘要】 本文采用电化学方法分别研究了3PE防腐层（外层聚乙烯（PE）、中间层(AD)和底层环氧粉末(FBE)）及其补口、补强材料在水溶液和土壤介质中保护电位与阴极剥离的关系，得到了3PE防腐层及其补口、补强材料发生阴极剥离的临界保护电位；测定了不同保护电位下的保护电流、电化学阻抗谱，得到了3PE防腐层及其补口、补强材料在发生阴极剥离后，保护电流及防腐层电阻值的变化规律，分析了防腐层在不同电位下抗电解质的渗透性能。利用红外光谱仪、综合热分析仪等对阴极剥离区域的产物进行了分析鉴定。研究结果表明：（1）存在缺陷的3PE防腐层及其补口、补强材料，在水溶液和土壤介质中的阴极保护电位临界值为断电电位-1.1V，当阴极保护断电电位低于-1.1V后，防腐层与基体之间出现了较严重的阴极剥离现象。（2）阴极保护电位低于管道断电电位-1.1V时，保护电流出现了一定的波动，并且阴极保护电流的波动随着阴极保护电位的负移而变得更加剧烈。（3）3PE防腐层及其补口、补强材料在水溶液及土壤中的阴极保护电流密度，反应了其阴极剥离的情况。在水溶液中，当阴极保护电流密度达到10mA/m2时，3PE防腐层开始出现阴极剥离现象，电流密度增大至100mA/m2后，防腐层阴极剥离明显加剧；土壤实验结果表明，当阴极保护平均电流密度达到0.1mA/m2，防腐层开始出现阴极剥离现象，平均电流密度急剧增大至1mA/m2时，防腐层的阴极剥离明显加剧。（4）随着阴极保护电位的负移，电化学阻抗谱变小，表明防腐层的抗阴极剥离性能和抗电解质渗透能力变差。（5）防腐层发生阴极剥离后，环境的pH值升高，由中性或弱酸性变碱性。（6）在发生阴极剥离的区域内，发现有白色粉末状的产物生成，经测定为钙、镁离子的沉淀物和环氧高分子粉末的混合物。更多还原

【Abstract】 Using electrochemical method, Three types of polythene anti-corrosion layer（3PE coating，heat shrinkable wraparound sleeve and heat shrink sleeve）were studiedin this paper by observing the changes of cathodic protection current with differentcathode polarization potentials in the cathode stripping process and cathodicdisbonding resistance performance in different conditions of the three kinds ofanti-corrosion layers. Using electrochemical impedance spectroscopy (EIS) method, bychoosing appropriate circuit to fit the impedance spectrum, we get the changingregularity of the resistance of the three kinds of polyethylene anti-corrosion layerunder different experimental conditions. The anti-electrolyte infiltration and cathodicdelamination performance of the three polyethylene anti-corrosion layer underdifferent cathodic polarization potential are studied. At the same time, using infraredspectrum,comprehensive thermal analyzer to analyze product of the cathode strippingarea of the sample.Results show that:(1) When the potential is more than-1.1V, the potential movesto negative excessively, the protection of3PE anti-corrosive coating will becomeinvalid ahead of time.(2)Polarization current of three polythene anti-corrosion layerappears to be different volatility when the potential is more than-1.1V polarization.(3)When cathodic protection current density was a sharp increase orders of magnitude,anticorrosive coating has a serious cathode detachment. Cathodic protection currentdensity up to10mA/m2,3PE anticorrosive coating began to appear cathode dissectionof the phenomenon, when the current density increases rapidly to100mA/m2,anti-corrosion layer stripping obvious cathode intensified. In the soil, the averagecurrent density of cathodic protection reached0.1mA/m2anticorrosive coating began to appear cathode dissection of the phenomenon, the average current density increasesrapidly to1mA/m2, anticorrosive coating cathode stripping increased obviously.(4)with the decreasing of cathodic potential and the increasing of time,the resistance ofthe specimen decreases obviously and even sharply reduces if the cathodic potential istoo negative. It is proved that the electrolyte is easier to infiltrate the ethyleneanti-corrosion layer if the cathodic is too negative, and make the anti-corrosion failureearlier as a result.(5)3PE anticorrosive coating the happening of the cathodestripping.(6) Products of the cathode stripping area is white. Using scanning electronmicroscopy, infrared spectrum, comprehensive thermal analyzer and X-rayfluorescence spectrometer to analyze that, we kown this products are inorganic salt andorganic compound mixing. Inorganic salt are calcium, magnesium ions in the cathodestripping alkaline environment of the formation of the sediment.organic compound are3PE anticorrosive coating layer or epoxy primer the glue in alkaline conditionsdisintegrate of the products.更多还原