环氧树脂基导电复合涂层的制备及防腐蚀性能

采用物理混合的方法在Q235碳钢表面制备一种环氧树脂基导电复合涂层。结果表明,E51环氧树脂清漆涂层存在大量的微泡,严重影响涂层的防护性能。导电复合涂层的微泡数量显著降低,经2000 h盐水浸泡和盐雾腐蚀实验结果表明,涂层未出现起泡、剥落等破坏,涂层下的Q235碳钢未发生腐蚀。电化学交流阻抗表明,随着浸泡时间的延长E51清漆涂层的阻抗急剧降低,而复合涂层的阻抗随着浸泡时间的延长而增大,表现出一定的自修复功能。复合涂层的电阻率和附着力分别为103Ω·cm数量级和9.12 MPa。     

铝粉含量对锌铝涂层微观形貌和耐蚀性的影响

采用扫描电子显微镜(SEM)、动电位极化技术及电化学交流阻抗技术,研究了3种不同铝粉含量的锌铝涂层表面形貌,以及涂层在3.5%NaCl溶液中的浸泡24h的自腐蚀电位、自腐蚀电流密度、阳极钝化情况和阻抗的变化。结果表明:随着铝粉含量的增加,涂层表面逐渐变得光亮、平整;涂层的自腐蚀电位依次升高,自腐蚀电流密度依次降低,当铝粉含量为50%时,涂层动电位极化曲线不存在钝化现象。涂层在3.5%NaCl溶液中浸泡24h的电化学阻抗谱拟合结果显示,铝粉含量较高时,涂层表面形成氧化膜,使得涂层的阻抗增大,降低水的渗入。     

石墨烯纳米片提升环氧富锌涂层耐蚀性的影响机制研究

环氧富锌涂层(ZRE)在海上风电、高速列车中防腐蚀方面得到了广泛应用,富锌涂层中作为牺牲阳极相的Zn粉利用率与涂层中的微导电通道有关.通过向ZRE中添加石墨烯纳米片(GNP)来提高ZRE的屏蔽性能和涂层中Zn粉的阴极保护效率,研究了添加0.5％(质量分数)GNP的ZRE涂层对碳钢保护的长效性影响.利用SEM和光学显微镜对模拟海水浸泡后的涂层表面微观形貌和碳钢基体的宏观形貌进行表征;通过对比涂层电化学阻抗中的特征低频阻抗|Z|0.01Hz和特征频率f-45°随时间的变化规律,发现GNP可显著提升ZRE涂层的耐蚀能力.采用微区电化学测试技术(SVET)研究了表面带模拟缺陷ZRE涂层在模拟海水中的腐蚀发展过程,发现GNP可显著扩展Zn粉的牺牲阳极保护区域,可将40％(质量分数,下同)Zn含量的ZRE涂层的|Z|0.01Hz提高1个数量级.在120 h浸泡周期内,含GNP的ZRE涂层可以为缺陷下的碳钢基体提供有效的阴极保护.进一步研究表明:0.5％的GNP对40 ％ZRE防腐蚀性能提升最明显,其次是70％ZRE和10％ZRE.这是因为ZRE涂层内均匀分散的GNP片层结构不仅可显著提升ZRE涂层的物理屏蔽性能,同时还通过GNP-Zn微电偶激活了Zn粉牺牲阳极活性,以及通过桥梁作用强化了Zn颗粒之间的联络导电能力,从而提高了涂层中Zn粉的利用效率.     

2A12铝合金在含Cl~-环境中的腐蚀行为和规律研究

通过室内浸泡模拟实验方法,研究了2A12铝合金在含Cl-典型环境中的腐蚀行为与电化学规律.采用扫描电镜观察了试样的组织和腐蚀产物的微观形貌,并用能量色散谱(EDS)分析了腐蚀产物元素组成.采用失重法分析了2A12铝合金腐蚀动力学规律,并采用电化学阻抗技术分析了2A12铝合金腐蚀后的电化学行为规律.实验结果表明,浸泡480 h后,2A12铝合金发生了明显的点蚀和小片状剥蚀,Cl-和第二相是促进点蚀形成和发展的主要原因;浸泡480 h后的动力学规律遵从幂指数规律;电化学阻抗谱中的Nyquist曲线由压缩的双容抗弧组成,随浸泡时间的延长,点蚀不断生成并发展,与腐蚀产物的产生与剥落综合作用,使电化学阻抗模值呈先减小后增大再减小的动态变化.     

Cl~-对天然气管道内涂层破损处局部腐蚀的影响

为了进一步了解天然气管道内涂层破损处在含Cl~-电解质溶液中的破损机理,以X80管线钢为基材,利用EIS(电化学阻抗谱法)和SKP(扫描开尔文探针测试法)等电化学检测技术,通过获取内涂层破损处的腐蚀电化学参数的特性,研究了Cl~-浓度对特定缺陷尺寸内涂层破损处局部腐蚀的影响,并探讨其腐蚀机理。EIS谱结果表明,不同Cl~-浓度下的腐蚀过程经历了大致相同的规律,即随着浸泡时间延长腐蚀电阻出现先减小后增大的趋势;SKP测试表明,破损处周边的涂层/金属界面存在较大的电位差,在界面最易发生腐蚀,并随着浸泡时间延长,推动着腐蚀向涂层内部渗透,进而引发涂层不断剥离。     

交流杂散电流对埋地Q235钢腐蚀行为的影响

土壤腐蚀中的交流杂散电流对管线钢腐蚀严重,为了弄清其影响规律,在室内模拟埋地Q235管线钢所处环境及受交流杂散电流腐蚀状况,通过调节交流电压改变交流信号的强度,利用失重试验和电化学技术研究了交流杂散电流强度对Q235钢腐蚀行为的影响。结果表明:Q235钢在土壤中的腐蚀同时存在交流杂散电流腐蚀和电化学腐蚀,其中交流杂散电流腐蚀可加剧电化学腐蚀过程;随着杂散电流强度的增大,腐蚀程度大大增加;在交流杂散电流存在的情况下,随着所施加交流电压的增大,Q235钢腐蚀电位负移,腐蚀电流密度增大,塔菲尔斜率r(βa/βc)相应减小,易发生阳极反应;随着埋地时间的增加,Q235钢在土壤中的腐蚀速率先增大后减小,逐渐趋于稳定。     

含缺陷涂层X80钢热影响区的电化学阻抗分析

为了进一步探讨X80钢涂层缺陷对耐土壤腐蚀性能及使用寿命的影响,将有无涂层缺陷的X80钢浸泡在玉门土壤模拟溶液中,采用电化学方法分析了其电化学阻抗谱。结果表明:无缺陷涂层的X80钢具有良好的防腐蚀效果;线缺陷涂层在不同测试期内的阻抗谱曲线都呈现为具有2个时间常数的双容抗弧特征;存在涂层缺陷时,外界腐蚀性介质会到达基体,使之腐蚀,随着腐蚀时间的延长,腐蚀产物会在缺陷处堆积;阴极反应形成的OH-增加会促使局部碱性环境的形成,进而导致X80钢涂层与基体界面剥离,发生缝隙腐蚀。     

基体表面粗化对氧化石墨烯涂层耐腐蚀性能的影响

金属表面的预处理往往是其涂层制备过程的重要步骤,为了探究碳钢表面状态对电泳沉积法制备氧化石墨烯涂层的影响,分别在粗化和抛光的碳钢表面制备了氧化石墨烯涂层,并通过激光散射仪测量了氧化石墨烯横向尺寸,采用三维表面测量仪对粗化碳钢表面形貌进行了表征,通过光学显微镜对涂层进行微观分析,并利用电化学工作站对涂层进行动电位极化曲线和电化学阻抗谱测试。结果表明：抛光面上的涂层有明显缺陷,疏松,其腐蚀电流密度是无涂层碳钢的1.5倍,阻抗值减小,耐腐蚀性能下降;较粗糙的表面有利于形成具有更均匀、致密的涂层,其腐蚀电流密度降低了10倍,阻抗值增大。表面粗化可以改善氧化石墨烯涂层质量,提升其耐腐蚀性能。     

循环加速腐蚀中紫外照射对环氧涂层老化行为的影响

采用傅里叶红外光谱(FTIR)、扫描电子显微(SEM)及电化学交流阻抗(EIS)技术,研究了环氧涂层在两种循环加速腐蚀(湿热-盐雾-疲劳和湿热-紫外-盐雾-疲劳)中的表面形貌、化学组成以及电化学阻抗特性。无紫外的循环加速腐蚀后涂层中心部分表面形貌无明显的变化,边缘部分涂层8个周期之后起泡破裂,破裂处出现了涂层下基体的腐蚀;有紫外的循环加速腐蚀过程中,紫外照射之后涂层表面粗糙度增加,出现粉化、失光现象,随循环加速腐蚀周期的增多涂层表面开始出现裂纹,且裂纹数量逐渐地增多。FTIR研究表明,无紫外的循环加速腐蚀后涂层结构无变化,而有紫外的循环加速腐蚀后涂层结构发生了明显的变化,高分子链断裂,O-H,C-H,C=C键及苯环等官能团消失。涂层在有紫外的循环加速腐蚀8个周期之后的电化学阻抗值仅为无紫外的1/2。     

结合EIS和WBE技术研究环氧涂层劣化

为研究环氧涂层在浸泡条件下的失效机理,结合丝束电极(WBE)和电化学阻抗谱(EIS)技术研究了环氧涂层浸泡在天然海水中的劣化过程, 同时分析了与涂层局部缺陷区相对应的电流密度分布和阻抗谱特征的差异．结果表明:丝束电极表面电流密度分布与EIS响应特征能够良好对应,两者结合使用可以实现对表面任意局部阳极和阴极区腐蚀过程的研究;涂层丝束电极的总阻抗响应主要与涂层局部缺陷最为严重处的电极过程特征相对应,而不能反映出其他区域的涂层劣化和涂层下基体的电化学过程信息;涂层下丝束电极出现了极性转换现象,但发生转换的原因各不相同．     

交流杂散电流作用下碳钢在土壤模拟溶液中的腐蚀

深入研究碳钢在交流作用下的腐蚀状况具有十分重要的意义。采用自行设计搭建的交流电流腐蚀试验装置,通过测试碳钢接地材料在土壤模拟溶液中的腐蚀电位、电化学曲线及腐蚀失重数据,对其在交流电杂散电流作用下的腐蚀状况进行研究,以期掌握在交流杂散电流作用下土壤中碳钢的腐蚀倾向和速率。结果表明:在杂散电流作用下,碳钢在土壤模拟溶液中的腐蚀倾向增大,且碳钢的腐蚀速率随着电流密度的增大而加快。     

静电喷涂聚酰亚胺涂层的防腐蚀性能

聚酰亚胺(PI)在防腐蚀方面前景良好,但目前国内报道不多。采用静电喷涂的方法在N80钢表面制备了一种聚酰亚胺防腐蚀涂层。通过盐雾试验、浸泡试验评价了涂层在不同腐蚀环境中的耐蚀性能;通过硬度测试和抗冲击试验评价了涂层的力学性能;采用红外光谱、电化学方法交流阻抗、扫描电镜(SEM)、能谱(EDS)等方法研究了涂层的失效过程。结果表明:涂层耐盐雾性能良好,3 080 h盐雾试验后仅表面发生微观物理破坏,在人工划痕处产生少量腐蚀产物;涂层在3.5%NaCl溶液和25%HCl溶液中耐蚀性能优异,电化学性能不随时间发生显著变化,但在涂层表面产生少量微观缺陷;涂层力学性能良好,但提高腐蚀介质温度会使得力学性能下降。     

Application of scanning electrochemical microscope in the study of corrosion of metals

Scanning electrochemical microscope (SECM) has become a very useful and powerful technique for probing a variety of electrochemical reactions in corrosion process due to its high spatial resolution and electrochemical sensitivity to characterize the topography and redox activities of the metal/electrolyte solution interface. Its capability for the direct identification of chemical species in localized corrosion processes with high spatial resolution would be more advantageous compared to other local probe techniques with only morphological characterization. In this review, the applications of the SECM in the study of early stages of localized corrosion, electroactive defect sites in passive films, local initiation of pits, degradation of coating properties on steels, and some combined methods through SECM integrated with other techniques have been summarized and commented. Finally, the optimization for SECM’s experiment design and operation as well as foreseeable application range has been proposed.     

Alternating current scanning electrochemical microscopy (AC‐SECM) studies on the surface of electrochemically polished NiTi shape memory alloys

Aiming at imaging local differences in electrochemical activity and related corrosion effects, the surface of electropolished NiTi was investigated using alternating current scanning electrochemical microscopy (AC‐SECM). Segregation‐related spatial variations in the rates of the anodic dissolution that are responsible for the formation of wavy surfaces during electropolishing could not be identified with AC‐SECM. Instead, the surface appeared rather uniform and did not reflect any (patterned) corrosion activity. Obviously, the anodically grown oxide film is highly isolating and passivating. This rationalizes the absence of the evolution of surface irregularities at the solid/liquid interface of NiTi‐shape‐memory alloys.     

Evaluation of the Corrosion Protection Performance of Epoxy-Coated High Manganese Steel by SECM and EIS Techniques

The corrosion protection performances of epoxy-coated Mn steel and carbon steel were evaluated by electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) analysis. EIS was performed on coated Mn steel with a scratch in a 0.1 M NaCl solution after a wet/dry cyclic corrosion test. The charge transfer resistance (R _ct) and film resistance (R _f) of the coated Mn steel displayed a higher value than the coated carbon steel. The increase in the charge transfer resistance and film resistance of the coated steel is due to the presence Mn in steel. SECM was conducted to estimate the corrosion protection performance of the epoxy-coated Mn steel immersed in a 0.1 M NaCl solution. It was found that dissolution of Fe²⁺ was suppressed at the scratch on the coated Mn steel due to the higher resistance for anodic dissolution of the substrate. SEM/EDX analysis showed that Mn was enriched in corrosion products at a scratched area of the coated steel after corrosion testing. FIB-TEM analysis confirmed the presence of the nanoscale oxide layer of Mn in the rust of the steel, which had a beneficial effect on the corrosion resistance of the coated steel by forming protective corrosion products in the wet/dry cyclic test.     

聚苯胺电活性涂层对碳钢的防腐蚀性能研究

将化学聚合所得的聚苯胺(PANI)粉末分散于羟基丙烯酸树脂中,可制备出粘接力强、有一定导电性的防腐蚀涂料.通过测量不同PANI含量涂层的开路电位、自腐蚀电流及涂层的交流阻抗谱随时间的变化,研究了聚苯胺含量对涂层防蚀性的影响.结果表明,聚苯胺含量过高或过低,涂层的防蚀性均不佳,只有当聚苯胺含量为10%～15%时,涂层的防蚀性最好.基于不同PANI含量的涂层经不同浸泡时间后等效电路的变化,探讨了聚苯胺的防腐蚀机制.     

Effect of cumulative gamma irradiation on microstructure and corrosion behaviour of X65 low carbon steel

X65 low carbon steel was exposed to Co-60 radiation source with 1.25 MeV gamma rays, and cumulatively absorbed gamma irradiation doses (1, 2, and 3 MGy) were obtained after different exposure time (333, 667, and 1000 h). The effect of cumulative gamma irradiation on microstructure and corrosion behaviour of the carbon steel in unirradiated aerobic Beishan groundwater at 25 °C was investigated by using positron annihilation, scanning vibrating electrode, and electrochemical techniques. Cumulative gamma irradiation increases vacancy intensity and decreases open circuit potential (OCP) of carbon steel. They indicate that the irradiated carbon steel is activated. Measured current density distribution above the irradiated carbon steel shows that cumulative gamma irradiation accelerates localized corrosion after 0.5 h of immersion. In contrast, the analysis of electrochemical impedance spectroscopy of the irradiated carbon steel indicates that localized corrosion is transformed into general corrosion after 12 h of immersion, which is also accelerated by cumulative gamma irradiation.     

镀锌层上单宁酸钝化膜的耐腐蚀性能

为提高镀锌板的耐蚀性,以硝酸、氟化铵、氧氯化锆为辅助成分,配制了单宁酸钝化液,并用其对镀锌板进行钝化处理。通过浸泡试验确定了最佳钝化工艺,通过扫描电镜（SEM）、Tafel曲线和交流阻抗谱研究了不同条件制备的钝化膜的形貌、耐蚀性。结果表明：镀锌层经1mol／L氢氧化钾溶液于65℃活化30s后再在含10g／L氧氯化锆的钝...     

Electrochemical characteristics of pipeline-steel with planar-defect epoxy-coating in simulated solutions of Ku'erle soil

An X70 pipeline steel and a low-carbon steel with different types of coating defects were studied using corrosion tests in Ku’erle simulated soil solution containing 0.6000 mol/L Cl^-. Electrochemical characteristics of the X70 pipeline steel with planar-defect epoxy-coating in simulated solutions of Ku’erle soil were tested. The results show that in 0.6000 mol/L Cl^- simulated solution, for low-carbon steel with coating defects (the area ratio is 4.91%), at free corrosion potential and with immersion time, the corrosion with disbond was more severe than that with a break or with break and disbond. In Ku’erle soil simulated solution, when the coating defect area ratio was increased gradually (0.39% → 1.57% → 6.28%), the corrosion of the X70 steel under coating with break was promoted gradually, and the influence of immersion time on the corrosion decreased. The influence of the immersion time on the corrosion was weakened when the defect area ratio increased to a certain degree.