磷酸锌对环氧涂层划痕的保护尺寸研究

用电化学阻抗谱(EIS)、电化学噪声(EN)及扫描电子显微镜(SEM)研究磷酸锌对磷酸锌/环氧涂层的保护作用及其保护尺寸的变化规律。研究表明,磷酸锌使划痕处的腐蚀产物变得致密,并对划痕有保护作用,随着划痕尺寸的增大其保护作用逐渐减弱。利用电化学噪声的散粒噪声理论并结合Gumbel随机分析方法研究磷酸锌的作用机制,发现磷酸锌填料的加入降低磷酸锌/环氧涂层的腐蚀生长概率,最终降低金属的腐蚀速度。     

环氧铝粉涂层在3.5%NaCl介质中的失效机理研究

采用电化学阻抗谱技术（EIS）研究了环氧铝粉涂层/Q235钢基体在3.5 %NaCl介质中的电化学腐蚀行为.利用扫描电镜（SEM）分析了涂层表面形貌,对涂层断面进行了能谱（EDX）线扫描和界面处腐蚀产物成分分析,探讨了环氧铝粉涂层的腐蚀失效机理.结果表明,腐蚀介质能通过涂层迅速渗透到涂层/基体界面,引起涂层电阻值的降低及界面处电化学腐蚀的开始.失效前涂层致密、连续,失效后涂层表面出现鼓泡、孔洞等现象.鼓泡是由腐蚀产物的体积膨胀和腐蚀介质渗入产生的压力推动共同产生的.界面处腐蚀产物主要是Fe和Al的氧化物及氯化物.涂层的失效机理为腐蚀介质渗入,涂层鼓泡、剥离.     

磷酸盐替代环氧富锌涂料中的锌粉制备环氧锌粉底漆

研究了复合磷酸锌替代环氧富锌涂料中的部分锌粉制备环氧锌粉底漆,在此基础上,以磷酸锌、APW-Ⅰ、钼酸锌替代复合磷酸锌,考察了4种防锈颜料涂层在3.5%NaCl腐蚀体系下的电化学腐蚀抑制性能,结合传统的盐水浸泡实验,评价4种颜料的防腐性能.结果表明:以复合磷酸锌取代环氧富锌涂料中的部分锌粉,制备环氧锌粉底漆,EIS研究发...     

采用聚类分析研究X70钢在库尔勒土壤中初期电化学噪声特征

采用电化学噪声（EN）技术研究了X70管线钢在库尔勒原土（含水量1.04%）中腐蚀初期（0 d~7 d）的腐蚀行为。通过时域谱分析、统计量分析和Q型聚类分析研究了电化学噪声特征以及相应的腐蚀状态信息,并与实际腐蚀状态和电化学阻抗谱（EIS）结果进行了对比。结果表明,基于EN统计量的谱系聚类分析法可用于解析土壤EN数据。聚类分析结果与时域分析、腐蚀形貌特征和EIS结果相吻合,且更加精确。根据聚类分析结果,可将研究体系中初期土壤局部腐蚀过程分为不稳定萌发期、快速发展期和稳定发展期三个阶段。     

环氧改性有机硅涂料耐热耐蚀性研究

研制了一种耐热防蚀涂层。涂层主要包括：环氧改性有机硅、钛白粉、磷酸锌、滑石粉和膨润土。性能测试表明，该涂层具有很好的耐热性和耐蚀性，可以在250℃下保护金属防止腐蚀。用电化学交流阻抗和扫描电镜等方法研究了钛白粉、磷酸锌、滑石粉和膨润土对涂层耐热和耐蚀性的影响。     

Zn粉含量及表面沾污对环氧富Zn漆电化学行为的影响

采用腐蚀电位、电化学阻抗谱(EIS)评价了Zn粉含量以及涂层／基体界面污染程度对环氧富Zn涂层的防腐蚀性能的影响并探索了富Zn涂层的失效机制。实验结果表明，当涂层中Zn含量较少时，Zn粉没有有效的阻挡作用。通过对可能的阻抗模型的分析，认为富Zn涂层的电化学阻抗谱的低频段是由Zn^2 从金属表面穿过腐蚀产物的扩散控制。涂层／基体界面污染不仅影响了环氧富Zn涂层的防腐蚀性能的发挥，也加速了钢铁基体的腐蚀。     

静水压力下Q235钢环氧涂层在3.5%NaCl溶液中的失效过程

利用电化学阻抗谱（EIS）研究了一种适用于深海环境的重防护环氧涂料在3.5%NaCl溶液中常压以及3.5 MPa下的破坏机制,探讨了静水压力对涂< 层失效过程的影响。结果表明,静水压力加速了电解质溶液在涂层中的渗透,对涂层的失效过程有着明显的影响。与常压下相比,静水压力下涂层电阻更小,涂层的失效过程更快;涂层/金属界面的电荷转移电阻更小,界面处金属腐蚀反应更快,涂层下金属基体更容易发生腐蚀,涂层的防护性能变差。     

三聚磷酸铝和氧化铈改性的环氧富镁涂层对AZ91D镁合金的保护性能研究

通过在环氧涂层中加入镁粉、三聚磷酸铝和氧化铈,制备了对AZ91D镁合金具有优良保护效果的耐蚀涂层,利用Machu测试、电化学阻抗 (EIS) 和扫描电镜 (SEM) 等方法研究了三聚磷酸铝和氧化铈对涂层保护性能的影响。结果表明,含50%Mg的环氧富镁涂层经过约2000 h浸泡后基体发生腐蚀,涂层失效,而添加10%三聚磷酸铝、0.25%氧化铈的40%Mg富镁涂层经过4488 h浸泡后基体仍然未发生明显腐蚀。三聚磷酸铝和氧化铈在富镁涂层中能够显著抑制Mg颗粒的活性,延长镁粉对镁合金基体的保护作用时间,同时也能一定程度上提高涂层的致密性,改善涂层的屏蔽性能,二者的作用相互叠加,有效提高了涂层的综合保护性能。     

硅烷处理对涂层/金属体系耐蚀性能的影响

采用电化学阻抗研究了输电塔架用Q345钢基体上环氧富锌涂层的失效过程,分析了硅烷处理对涂层/金属体的耐腐蚀性能的影响。结果表明,环氧富锌涂层/未表面处理金属体系经过240h的浸泡腐蚀后涂层失去保护作用;而环氧富锌涂层/硅烷处理金属体系经过408 h的浸泡腐蚀后涂层失去保护作用。经阻抗谱和孔隙率与吸水率分析表明,Q345钢经硅烷表面处理后延缓了腐蚀性介质侵入涂层,较大地提高了体系的抗腐蚀能力。     

添加纳米锌粉环痒涂层腐蚀电化学行为

用电化学阻抗谱(EIS)技术研究了添加不同质量 百分比浓度的纳米锌粉环氧涂层的腐蚀电化学行为，并与环氧清漆(不含颜料)涂层的腐蚀电化学行为进行对比.结果表明，添加不同质量百分比浓度纳米锌粉环氧涂层与环氧清漆涂层具有不同的电化学阻抗谱特征.纳米锌粉的添加量对涂层的防护性能有显著影响，添加不同质量百分比浓度纳米锌粉环氧涂层防腐蚀性能的优劣顺序为：环氧清漆涂层>20mass%>10mass%>2mass%纳米锌环氧涂层.添加纳米锌粉对环氧涂层的防护性能有2方面的影响：一方面使涂层中的微观缺陷大大增多，涂层的防护性能降低；另一方面，由于锌粉的腐蚀产物可将涂层中部分缺陷堵塞，从而对涂层的防护性能有提高作用.由于在所研究的质量百分比浓度范围内(2mass%～20mass%)，前者起了主导作用，所以综合作用的结果是使涂层的防护性能变差.  s.     

The role of a zinc phosphate pigment in the corrosion of scratched epoxy-coated steel

The roles of a zinc phosphate pigment in the corrosion of scratched epoxy-coated steel were studied by means of electrochemical impedance spectroscopy, electrochemical noise measurement and scanning electrochemical microscopy. The experimental results of electrochemical noise measurement and electrochemical impedance spectroscopy revealed that zinc phosphate exhibited inhibition effect on the corrosion of the scratched epoxy-coated steel. The scanning electrochemical microscopy results implied that the scratched surface under zinc phosphate coating was re-healed by an insulating film. The mechanism of the inhibition effect of a zinc phosphate pigment was analyzed based upon the combined stochastic theory and shot noise theory using the Weibull distribution and Gumbel distribution function.     

模数对水性硅酸钾富锌涂层电化学行为的影响

通过测量涂层腐蚀电位与涂层电化学交流阻抗,研究了水溶性K2SiO3溶液的模数(SiO2/K2O摩尔比)对水性无机富锌涂层电化学行为的影响.结果表明,水性无机富锌涂料随着水基模数的增加,涂层腐蚀电位增高,涂层对腐蚀介质的屏蔽性能增强,涂层中锌粉颗粒的活性溶解阻力增大.用扫描电子显微镜(SEM)观测不同模数水性无机富锌涂层的结构表明,水性无机富锌涂料水基模数的增加使涂层中锌粉颗粒之间充分交联,涂膜强度增大,涂层中锌粉颗粒之间的缝隙减小,涂层的致密性增强.     

The role of zinc aluminum phosphate anticorrosive pigment in Protective Performance and cathodic disbondment of epoxy coating

Protective performance and cathodic disbondment of epoxy coating pigmented with zinc aluminum phosphate (ZPA) were studied in this work. In solution, superior corrosion inhibition of ZPA extracted from EIS and electrochemical noise data was connected to deposition of a protective layer. EIS evaluation of the pigmented coatings indicated significant effect of modification of zinc phosphate on the protective performance as well as resistance to cathodic disbonding. Compared to ZPA, introduction of zinc phosphate resulted in inferior performance in cathodic disbonding test. In presence of ZPA, precipitation at disbonding front inferred from EIS data was confirmed by SEM.     

Corrosion protection of Mg–5Li alloy with epoxy coatings containing polyaniline

The protective ability of epoxy coating containing polyaniline (PANI coating) on Mg–5Li alloy in 3.5% NaCl aqueous solution has been studied by means of EIS and electrochemical noise measurements (EN). The results of EN and EIS revealed that the PANI coating protected Mg–5Li alloy from corrosion perfectly. XPS results indicated that the presence of polyaniline changed the chemical structure of the corrosion film on the alloy surface. An analysis of the electrochemical noise data based on stochastic analysis indicated that the corrosion growth probability of Mg–5Li alloy beneath the coating was decreased by the addition of polyaniline.     

腐蚀电化学中的频谱分析研究

简要介绍了我们实验室中进行的电化学阻抗频谱(EIS)与孔蚀诱导期中电化学噪声(EN)的谱功率密度(SPD)的研究进展。通过引入定态过程稳定性条件,导出了具有2和3个时间常数EIS的法拉第导纳公式,将它们应用于EIS数据分析的工作也正在进行中;发展了混合电位下的EIS理论并成功地应用于界面型缓蚀剂研究。证明了孔蚀诱导期中EN的SPD的特征是:极低频率下为“白噪声”,在较高频率下则转变为f~n噪声,n的数值在2至4之间。导出了相应的理论公式。     

有机涂层防护性能的电化学研究进展

曝晒、盐雾、浸泡、干湿循环、老化等传统的有机涂层防护性能研究方法,因测试周期长,测试结果多为定性分析,不能使涂层材料进行快速检验而投入评估使用.正是由于传统测试方法存在许多局限性,故综述了稳态电化学测试方法和暂态电化学测试方法这两种新技术在有机涂层防护性能中的应用与进展.介绍了动电位极化曲线法、极化电阻法等稳态电化学测试方法,这类方法主要反映涂层的极化电阻和腐蚀速度,并且方法简单,可直接分析实验数据,被广泛应用于有机涂层的失效分析中.而暂态电化学测试方法主要包括电化学阻抗法(EIS)、局部阻抗法(LEIS)、扫描Kelvin探针法(SKP)及电化学噪声(EN)等,主要用于研究涂层防护机制和局部缺陷.目前,在有机涂层防护性能和机理研究中,应用最多的是电化学交流阻抗法.丝束电极法(WBE)、扫描电化学显微镜(SECM)以及原子力显微镜(AFM)用于研究金属/涂层界面物理化学变化规律.阐述了上述方法在涂层防护研究中的应用成果及其优势和不足,指出对于深层次的涂层防护研究,需要应用多种测试手段,从不同的角度和方面综合分析,全面评估涂层的使用寿命.     

热浸Zn-Ti合金镀层的耐腐蚀性能

为了抑制热镀锌过程中因含硅活性钢引起的镀层超厚生长,采用在纯锌浴中加Ti的方法,研究了热浸Zn-Ti合金镀层的耐蚀性能.采用浸泡腐蚀、电化学极化、交流阻抗以及X射线光电子能谱等方法,研究了热浸Zn-Ti合金镀层的耐蚀性能.结果表明:Zn-Ti舍金镀层在5%NaCl溶液中的自发腐蚀倾向小于Zn镀层,其极化电阻和交流阻抗增大,腐蚀电流密度减小,耐蚀性能提高.Zn-Ti镀层表面形成的氧化膜由ZnO和TiO2组成.Zn-Ti合金镀层的耐腐蚀性能优于纯锌镀层是由于在镀层表面形成了更加稳定的TiO2膜.     

Electrochemical evaluations of zinc-rich epoxy primers modified with polyaniline and exfoliated polyaniline graphite nanocomposite

ABSTRACT

Polyaniline (Pani) and exfoliated polyaniline graphite (EPaniG) nanocomposites were used to modify the protective properties of an epoxy zinc-rich primer (ZRP). The corrosion resistance properties of primers were evaluated in 3.5% sodium chloride solution for a period of 120 days via electrochemical noise (EN) and electrochemical impedance spectroscopy (EIS). EN data were analysed via Wavelet and Hilbert spectra analysis to evaluate the protection mechanism of different ZRP coatings during immersion. Coating resistance and charge transfer resistance of the primers were evaluated by EIS measurements. Results showed good compatibility between |Z|_0.01Hz from EIS measurements and mean noise resistance which results from EN data and these evaluations allowed the examination of coating performances during immersion. Free corrosion potential (E_corr) measurements and salt spray test revealed that both the cathodic protection and barrier properties of the ZRP primer were improved after addition of EPaniG nanocomposite to the ZRP sample.     

Preparation and characterization of inorganic and organic coatings on AZ91D magnesium alloy with electroless plating pretreatment

In this paper, a protective coating scheme was applied for the corrosion protection of AZ91D magnesium alloy. Electroless Ni coating (EN coating) as bottom layer, electrodeposited Ni coating (ENN coating), and silane‐based coating (ENS coating) as top layer, respectively, were successfully prepared on AZ91D magnesium alloy by combination techniques. Scanning electron microscopy and X‐ray diffraction were employed to investigate the surface and phase structure of coatings, respectively. The electrochemical corrosion behaviors of coatings in neutral 3.5 wt% NaCl solution were evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The corrosion testing showed that the three kinds of coatings all could provide corrosion protection for AZ91D magnesium alloy to a certain extent, and the corrosion resistance of ENN and ENS was superior to EN. In order to further study the corrosion protection properties of ENN and ENS, a comparative investigation on the evolution of EIS of ENN and ENS was carried out by dint of immersion test in neutral 3.5 wt% NaCl solution. The results indicated that, compared with ENN, the ENS could provide longer corrosion protection for AZ91D magnesium alloy. It is significant to determine the barrier effect of each coating, which could provide reference for industry applications.