富镍导电涂层在模拟盐碱地土壤溶液中的耐蚀性

在高黏度的丙烯酸树脂中加入镍粉、消泡剂及其他助剂制备出具有导电功能的防腐涂料并涂覆在作为接地材料的碳钢上。通过测试涂层的表面接触电阻来表征涂层的导电性。用电化学阻抗谱研究了含不同镍粉质量分数的导电涂层在模拟轻度、中度、重度盐碱地土壤溶液中的耐蚀性,并用光学显微镜观察了浸泡61 d后涂层的表面形貌。结果表明,镍粉用量越多,涂层导电性越好。在不同盐碱地溶液中,随浸泡时间延长,涂层阻抗都呈现先上升后下降的趋势;而随模拟溶液中盐分浓度增加,涂层的阻抗下降。镍粉含量大,涂层的阻抗反而小,表面腐蚀严重,耐蚀性更差。     

H13模具钢氮碳共渗表面沸石涂层的制备及耐蚀性

为提高H13模具钢氮碳共渗后表面的耐蚀性,通过一次水热合成法在其表面制备了沸石涂层。采用扫描电子显微镜(SEM)和能谱仪(EDS)分别表征了沸石涂层的结构特征以及元素组成。采用Tafel极化曲线测试、电化学阻抗谱测量以及3.5%NaCl溶液室温浸泡实验考察了沸石涂层的耐蚀性。结果表明,采用一次水热合成法制备的涂层由交联生长的沸石颗粒构成,其厚度约为18μm。在3.5%NaCl溶液中,其腐蚀电流密度比H13氮碳共渗基体低2个数量级,浸泡840 h后的低频阻抗模值比没有浸泡时下降了约一个数量级,但仍比氮碳共渗基体高1.5倍。在3.5%NaCl溶液中浸泡1 800 h后,沸石涂层在微观上出现了大量的腐蚀产物,表明它已逐渐失效。     

纳米改性环氧粉末涂层在塔河油田的适应性研究

利用高温高压釜模拟纳米改性环氧粉末内涂层在某油田的服役工况,以涂层的热扫描特征为切入点,研究了它在中性盐水、高酸、强碱中的耐蚀性,以及在模拟工况条件下气、油、水三相中的耐蚀性,并对其在6种模拟工况条件下的电化学阻抗谱特征进行了分析。结果表明,涂层在中性盐水、高酸、强碱中浸泡30d后的玻璃化转变温度超过90℃,可在较高的温度下使用,并具有较好的耐化学腐蚀和工况腐蚀特征。即使在模拟工况中试验30d后,其电化学阻抗值仍高于107Ω·cm~2。探讨了涂层的防腐机制。     

16MnR钢表面复合涂层耐蚀性的电化学阻抗谱研究

在16Mn R钢上用电弧喷涂制备了铝涂层,然后涂装了纳米环氧涂层体系作为其封闭涂层。通过电化学阻抗谱(EIS)和浸泡试验研究了铝/纳米环氧封闭复合涂层在3.5%Na Cl溶液中的耐蚀性以及防护机制。复合涂层体系对基体的保护过程可以分为4个阶段:介质渗入有机涂层阶段,铝涂层与介质接触阶段,铝涂层腐蚀产物形成屏蔽层阶段,以及腐蚀产物渗透封堵有机涂层孔隙阶段。腐蚀介质不断渗透到有机涂层的孔隙,使其体积膨胀,孔隙增大,导致涂层电阻Rc随浸泡时间延长而减小。     

紫外光固化环氧丙烯酸酯涂料的制备及耐蚀性能研究

以E-51环氧树脂和丙烯酸为原料合成出光敏性环氧丙烯酸酯低聚物,制备了不同组成的紫外光固化涂料.合成产物的红外光谱分析结果表明,光敏性碳碳双键基团被引入到环氧树脂结构中;固化后涂层的红外表征结果表明,碳碳双键C=C的特征吸收峰消失,涂层固化较完全.在无水乙醇、5%NaOH和5%H2SO4溶液中的浸泡实验以及在3.5%NaCl溶液中的电化学阻抗谱测量结果表明,涂层具有较好的耐蚀性,其耐蚀性随着涂料中环氧丙烯酸酯含量的增加,呈先提高后下降的趋势.当环氧丙烯酸酯含量为40%,二缩三丙二醇双丙烯酸酯含量为50%时,所得涂层的耐蚀性最佳.     

基于电化学阻抗谱的航空用环氧底漆失效过程及动力学规律研究

采用电化学阻抗谱研究了航空用环氧底漆在3.5%NaCl溶液中连续浸泡条件下的失效过程。结果表明,涂层在连续浸泡条件下的失效过程主要分为五个阶段,即浸泡初期阶段、渗透初期阶段、渗透中期阶段、渗透末期阶段和涂层失效阶段。通过对不同浸泡时期的Nyquist图和Bode图进行分析,得到了涂层电阻、电容、孔隙率和吸水率随浸泡时间的变化规律,通过分析低频区阻抗|Z|_(0.01)随浸泡时间的变化,得到了|Z|_(0.01)随浸泡时间变化的动力学方程。     

纳米N/TiO_2复合醇酸树脂涂层的防护性能研究

通过溶胶-凝胶法制备了N掺杂TiO2纳米颗粒(N/TiO2),采用X射线衍射仪和透射电镜对其进行了表征,并与醇酸树脂混合制成纳米N/TiO2复合醇酸树脂涂层。采用盐雾试验、动电位极化曲线和电化学交流阻抗技术研究了纯醇酸树脂涂层和纳米N/TiO2复合醇酸树脂涂层在海水环境中对碳钢的防护性能。结果表明:N/TiO2粉末的晶型为锐钛矿型,粒径及结晶度均低于纯TiO2。在醇酸树脂中添加1%的纳米N/TiO2,所得复合涂层可有效抑制海水在其中的扩散,显著提高了醇酸树脂涂层的耐蚀性:耐盐雾时间从480 h提升到900 h;在相同的浸泡时间内,0.01 Hz时的阻抗模值均高于醇酸树脂涂层;自腐蚀电位正移。     

乳化沥青涂层防腐性能研究

利用极化曲线法,结合电化学交流阻抗技术研究了涂覆在A3钢上乳化沥青涂层在不同的涂层厚度、不同的腐蚀时间、不同的介质中电化学腐蚀行为,结果表明:乳化沥青涂层具有较大的阻抗值和较低的腐蚀电流密度,同时在较长的浸泡时间后依然具有很好的防腐蚀能力。因此可作为水性环保防腐涂料使用。     

6061铝合金搅拌摩擦焊焊缝微弧氧化涂层的耐蚀性

对6061铝合金搅拌摩擦焊(FSW)焊缝进行微弧氧化(MAO)处理来提高其耐蚀性能。采用扫描电子显微镜(SEM)和X射线能谱仪(EDS)分析了FSW焊核区与母材区的表面和截面形貌及其组成,通过极化曲线和电化学阻抗谱(EIS)研究了焊核区、母材区微弧氧化前后的耐蚀性能,并通过盐水浸泡实验进一步验证了其耐蚀性。微弧氧化涂层能够显著提高搅拌摩擦焊接头的耐蚀性能,且焊核区微弧氧化涂层的耐蚀性比母材区微弧氧化涂层更好。     

缓蚀剂对磷酸镁涂料防腐性能的影响

为了提高磷酸铵镁水泥(MAPC)涂料的防腐性能,在MAPC涂料中加入少量的三聚磷酸铝(ATP)进行改性并涂覆在Q235钢表面。根据动电位极化曲线和电化学阻抗谱测试结果分析了ATP改性MAPC涂层的防腐性能及防腐机理,采用扫描电镜-能谱分析(SEM-EDS)及X射线衍射(XRD)分析了涂层的形貌与成分,通过中性盐雾试验考察了涂层的耐蚀性。结果表明：在3.5%NaCl溶液中浸泡28 d后,添加4%(质量分数)ATP后,MAPC涂层的腐蚀电流密度减小,腐蚀电位正移,电荷转移电阻较空白组明显提高,屏蔽性增强,且中性盐雾测试1 440 h后涂层表面未出现鼓包、脱落等现象,内部基材没有锈蚀痕迹。     

Study of impedance model and water transport behavior of modified solvent-free epoxy anti-corrosion coating by EIS II

This work studied the evolution of an impedance model of 60 μm modified solvent-free epoxy anti-corrosion coating on a Q235 steel surface in 3.5% NaCl solution using electrochemical impedance spectroscopy. The electrochemical process of the system was divided into five stages. During the early stage of immersion, water absorption occurred mainly at the coating, coating resistance decreased, and coating impedance deviated from purely capacitive characteristics. The corrosion reaction started after water permeated into the metal/coating interface. During the mid-immersion stage, the electrochemical reaction at the coating/metal interface was controlled by semi-infinite diffusion of corrosion products due to the barrier effect of the coating. The types of corrosion product diffusion gradually became finite layer diffusion and barrier layer diffusion with the clogging of coating pores. Logarithm of coating capacitance and the square root of time showed a linear relationship in the early immersion stage, which was a typical characteristic of Fick’s diffusion. Afterwards, increase in the coating capacitance slowed down, and a non-Fickian diffusion process occurred, which presented the two-stage absorption characteristics. Water diffusion coefficient in coating was calculated to be 2.95 × 10^?10 cm²/s, while volume fraction and total water absorption at saturation of coating were 2.3% and 185 μg, respectively, indicating good water resistance and protective properties of the coating. The water kinetic equation in the coating which can reflect the whole Fick diffusion process of water and containing time and location variables was obtained via the Fick diffusion equation and three-dimensional images of water distribution in the coating were drawn by transforming the dynamic equation into programs.     

Corrosion resistance of phosphate coatings obtained by cathodic electrochemical treatment: Role of anode–graphite versus steel

The formation of phosphate coatings by cathodic electrochemical treatment using graphite and steel anodes and evaluation of their corrosion resistance is addressed in this paper. The type of anode used, graphite/steel, has an obvious influence on the composition of the coating, resulting in zinc–zinc phosphate composite coating with graphite anode and zinc–iron alloy–zinc phosphate–zinc–iron phosphate composite coating with steel anode. The corrosion resistance of the coating is found to be a function of the composition of the coating. The deposition of zinc/zinc–iron alloy along with the zinc phosphate/zinc and zinc–iron phosphate using graphite/steel anodes has caused a cathodic shift in the E_corr compared to uncoated mild steel substrates. The i_corr values of these coatings is very high. EIS studies reveal that zinc/zinc–iron alloy dissolution is the predominant reaction during the initial stages of immersion. Subsequently, the formation of zinc and iron corrosion products imparts resistance to the charge transfer process and increases the corrosion resistance with increase in immersion time. The corrosion products formed might consist of oxides and hydroxychlorides of zinc and iron. The study suggests that cathodic electrochemical treatment could be effectively utilized to impart the desirable characteristics of the coating by choosing appropriate anode materials, bath composition and operating conditions.     

Corrosion behaviour of electrogalvanized steel in sodium chloride and ammonium sulphate solutions; a study by E.I.S.

Zinc and zinc-nickel (13% Ni) electrodeposits were passivated by dipping in chromate baths and characterized by scanning electron microscopy. The corrosion behaviour was studied using a.c. electrochemical techniques; electrochemical impedance spectroscopy (EIS) measurements were performed at open circuit and under galvanostatic control during the 24 h immersion time. In sodium chloride solution the zinc-nickel electrodeposits show a better corrosion resistance compared to the pure zinc coatings. During the immersion time, a surface nickel enrichment was observed which, together with the zinc corrosion products, acts as a barrier layer reducing the total corrosion rate. In the same solution the passivation treatment improves the corrosion resistance of the electrodeposits; nevertheless, on zinc substrates, the protection exerted by the chromate film is not, always effective during the immersion time. On the contrary the chromate coating on zinc-nickel substrates induces a remarkable and durable improvement of the corrosion resistance reducing the zinc dissolution almost completely. In the ammonium sulphate solution, the corrosion mechanism is significantly influenced by hydrogen reduction on the zinc-nickel surfaces, and by the production of a local surface acidity which is aggressive for the chromate coatings.     

The corrosion resistance of 316L stainless steel coated with a silane hybrid nanocomposite coating

The present work aims at evaluating the corrosion resistance of 316L stainless steel pre-treated with an organic–inorganic silane hybrid coating. The latter was prepared via a sol–gel process using 3-glycidoxypropyl-trimethoxysilane as a precursor and bisphenol A as a cross-linking agent. The corrosion resistance of the pre-treated substrates was evaluated by neutral salt spray tests, linear sweep voltammetry and electrochemical impedance spectroscopy techniques during immersion in a 3.5% NaCl solution. In addition, the effect of the drying method as an effective parameter on the microscopic features of the hybrid coatings was studied using Fourier transform infrared spectroscopy and scanning electron microscopy. Results show that the silane hybrid coatings provide a good coverage and an additional corrosion protection of the 316L substrate.     

The corrosion resistance of 316L stainless steel coated with a silane hybrid nanocomposite coating

The present work aims at evaluating the corrosion resistance of 316L stainless steel pre-treated with an organic–inorganic silane hybrid coating. The latter was prepared via a sol–gel process using 3-glycidoxypropyl-trimethoxysilane as a precursor and bisphenol A as a cross-linking agent. The corrosion resistance of the pre-treated substrates was evaluated by neutral salt spray tests, linear sweep voltammetry and electrochemical impedance spectroscopy techniques during immersion in a 3.5% NaCl solution. In addition, the effect of the drying method as an effective parameter on the microscopic features of the hybrid coatings was studied using Fourier transform infrared spectroscopy and scanning electron microscopy. Results show that the silane hybrid coatings provide a good coverage and an additional corrosion protection of the 316L substrate.     

Study of impedance model and water transport behavior of modified solvent-free epoxy anticorrosion coating by EIS

This paper studies the evolution of impedance model of 30 μm solvent-free epoxy coating on Q235 steel surface in 3.5% NaCl solution using electrochemical impedance spectroscopy. The electrochemical process of the system was divided into five stages. Water absorption occurred at the coating mainly during the early stage of immersion. In the meantime, coating resistance became smaller and coating impedance deviated from purely capacitive characteristics. After water permeated into the metal/coating interface, corrosion reaction began. During the middle stage of immersion, due to the barrier effect of the coating, the electrochemical reaction at the coating/metal interface was controlled by diffusion of corrosion products. Since the coating prepared was relatively thin, transport distance was short for water, which could easily reach the coating/metal interface. During the middle-late stage of immersion, coating peeled off from the metal surface, diffusion of water molecules gradually turned to a macroscopic infiltration process, and the coating lost its protective effect. A logarithm of coating capacitance and the square root of time showed a linear relationship in the early immersion stage, which was a typical characteristic of Fick’s diffusion. Water diffusion coefficient in the coating was calculated to be 8.23 × 10^?11 cm²/s, while volume fraction and total water absorption at saturation of coating were 3.5% and 105 μg/cm², respectively, indicating good water resistance and protective properties of the coating. By solving the Fick’s diffusion equation, the kinetic equation which described the diffusion of water in the coating and included time and location variables were obtained.     

双向脉冲电镀纳米级镍镀层耐腐蚀性能研究

用直流电沉积法制备了普通光亮镍镀层,同时用双向脉冲电镀制备了纳米级镍镀层。用X射线衍射(XRD)、扫描电镜(SEM)等方法研究了镀层的晶粒尺寸、组织结构和表面形貌,通过孔隙率测定、盐雾试验、静态浸泡腐蚀失重试验和电化学方法等测试了镀层的耐蚀性能。结果表明,采用双向脉冲电流制备的纳米级镍镀层的耐蚀性明显优于普通直流镍镀层。     

Electrochemical corrosion behavior of composite coatings of sealed MAO film on magnesium alloy AZ91D

Protective composite coatings were prepared on magnesium alloy AZ91D by micro-arc oxidation (MAO) treatment plus a top coating with sealing agent using multi-immersion technique under low-pressure conditions. The corrosion resistance of AZ91D alloy with composite coatings was superior evidently to that with merely MAO film. SEM observations revealed that the sealing agent was integrated with MAO film by physically interlocking; therewith covered uniformly the surface as well as penetrated into pores and micro-cracks of MAO film. The anti-corrosion properties in 3.5% NaCl solution of the composite coatings were evaluated by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Based on the results of chronopotentiometric (E ∼ t) and EIS measurements for long time immersion in 3.5% NaCl solution, appropriate equivalent circuits for the composite coatings system were proposed. It follows that due to the blocking effect of the sealing agent in pores and cracks in MAO film, the composite coatings can suppress the corrosion process by holding back the transfer or diffusion of electrolyte and corrosion products between the composite coatings and solution during immersion.     

生物基聚苯并嗪/纤维素纳米晶超疏水防腐蚀涂层的制备及性能

以腰果酚、十八胺和多聚甲醛为原料合成出生物基苯并嗪单体,以单宁酸为固化剂,采用差示扫描量热分析技术和红外光谱考察了苯并嗪单体的热固化行为,结果表明单宁酸可以有效降低苯并嗪的开环固化温度。在钢片表面首先制备聚苯并嗪涂层作为底漆,再通过在涂层中掺杂氨基修饰纤维素纳米晶制备面漆,构建出静态水接触角为161.1°±2.9°的生物基超疏水防腐蚀涂层（PBTC）。该超疏水涂层表现出良好的耐高低温性能和耐刮擦性。电化学测试结果表明PBTC涂层在NaCl水溶液中浸泡30天后仍然具有良好的防腐蚀性能。     

镀锌层单宁酸钝化膜的耐蚀性

为提高镀锌层的耐蚀性,以氟钛酸钾、双氧水、硝酸为辅助成分,制备了单宁酸钝化液,并对低碳钢上的碱性镀锌层进行了钝化处理.通过质量分数为5%的NaCl溶液浸泡试验,确定了最佳钝化液组成和钝化工艺条件为:单宁酸40 g/L,HNO3 5 mL/L,氟钛酸钾10g/L,H2O2 60 mL/L,温度25℃,时间20～30 s....