涂层酸性盐雾环境下失效过程的电化学阻抗谱分析

目的探究车辆装备有机涂层在沿海地区酸雨污染环境下的腐蚀行为。方法利用电化学阻抗谱技术,对金属漆涂层酸性盐雾环境下的腐蚀失效过程进行研究,分析其电化学阻抗谱特征及涂层电容的变化规律,并利用10 Hz下的中频相位角(θ_(10))和阻抗模值(|Z|_(10))评价金属漆涂层的防护性能。结果金属漆涂层的腐蚀失效过程大致经历3个阶段,即涂层完好阶段、涂层防护性能下降阶段和涂层失效阶段,随着腐蚀时间的增加,涂层电容逐渐增大,当θ1028.78°,|Z|101.78×10~7?·cm~2时,涂层基本丧失腐蚀防护能力。结论利用中频相位角和阻抗模值可以有效地评价金属漆涂层酸性盐雾环境下的腐蚀防护性能,为车辆装备在沿海地区的腐蚀防护提供技术支撑。     

金属涂层与有机涂层在5%NaCl溶液中的腐蚀特征

为了解金属锌涂层与有机涂层性能的变化规律,测试了电弧喷涂锌涂层和有机涂层在5%NaCl溶液中的电化学阻抗谱(EIS),并结合扫描电镜(SEM)观察,分析了金属涂层及有机涂层腐蚀特征的变化过程.结果表明:锌涂层表现出自封闭作用,其防护性能主要体现在腐蚀后期,而有机涂层在腐蚀初期有较好的防护性能;锌涂层的电化学行为可以用等效电路Rs(RpoCc)(RpCdl)来描述;随着浸泡的进行,锌涂层极化电阻增大,有机涂层极化电阻减小.     

有机防护涂层综合加速试验老化动力学模型的建立

为了预测舰船航空飞行器有机防护涂层的服役寿命,模拟了其海洋服役环境:紫外光照射-周期浸润-温度冲击。采用电化学交流阻抗技术进行了综合加速试验,研究有机防护涂层的老化动力学过程,以交流阻抗低频模值为涂层性能的参数,建立了有机防护涂层的老化动力学方程。结果表明:在综合因素加速作用下,有机防护涂层的老化过程可以分为涂层完好、被腐蚀介质渗透、失去防腐蚀作用3个阶段;所建的涂层老化动力学模型有助于确定有机防护涂层的服役寿命和耐久性能,为其使用和维护提供了依据。     

外加应变对航空有机涂层防护性能的影响

设计了一种板条形涂层试样预应变施加方法,并通过原始标定和显微观察的方法定量确定有机涂层应变量,以此模拟航空涂层防护体系在服役过程中遭受的应变。将施加了不同应变的板条形有机涂层试样进行户外暴晒,样品所处条件与实际服役中自然环境因素-力学因素耦合作用的情况更为接近,从而可以得到更为准确的防护性能评价结果。结果表明:无外加应变状态的锌黄丙烯酸聚氨酯涂层的阻抗模值随着在万宁自然老化时间的延长而下降,在户外暴晒36个月的过程中,涂层的阻抗模值从1.8×109Ω下降到4.7×105Ω;经过户外暴晒后,外加压应变状态和外加拉应变状态涂层试样的阻抗模值都发生下降,但外加拉应变状态涂层模值降低的幅度更大,表明外加拉应变对有机涂层防护性能影响更大。     

海洋环境下磁场对电磁屏蔽涂层保护性能的影响

采用电化学阻抗谱(EIS)研究了3.5%(质量分数)NaCl溶液中外加磁场对Ni基电磁屏蔽涂层单、双层体系保护性能的影响,并采用体视显微镜与扫描电子显微镜对浸泡后涂层的表面及截面形貌特征进行了观察。结果表明,单层Ni基涂层体系下,磁场的作用表现为阻滞了溶液的扩散,使得其低频阻抗模值|Z|0.01Hz随浸泡时间的增加下降速度减缓,这是由于磁场使涂层中Ni颗粒重新排布,减少了涂层内缺陷;对于电磁屏蔽涂层/丙烯酸聚氨酯清漆双层体系,EIS结果表明外加磁场使涂层|Z|0.01Hz下降更快,而磁场方向对|Z|0.01Hz的变化规律无明显影响。这说明尽管磁场优化了底漆中Ni颗粒在涂层中的分布,提高了电磁屏蔽底漆的保护性,但是对于丙烯酸聚氨酯面漆的失效过程,磁场对电解质扩散的加速作用占主导地位,二者叠加总体来说磁场加速了双层涂层体系腐蚀过程。     

有机防护涂层老化研究进展

综述了以聚脲及聚氨酯涂层为代表的有机防护涂层在不同测试方法(SEM、AFM、FTIR、EIS、ATR等)和不同试验环境下的耐老化性能,包括有机防护涂层降解老化研究、腐蚀介质在涂层内的渗透性研究、涂层混凝土氯离子渗透性研究、有机涂层的老化研究及电化学阻抗测试研究。研究结果表明:涂层在不同老化条件下表现出不同的老化行为,紫外线/盐雾循环人工加速老化及Cl-在涂层中扩散最终都能导致涂层形貌破坏,防护功能下降;有机涂层附着力丧失及涂层失效程度可用涂层电容(C)值的迅速增加和涂层电阻(R)值的急剧降低为指标进行衡量。     

漆酚钛涂层在模拟高温、高CO2环境中的防护性能研究

为提升碳钢在高温、含CO₂环境盐水介质中的耐蚀性,采用钛酸四丁酯在丙二醇甲醚醋酸酯的增容条件下与漆酚交联形成漆酚钛涂料,并涂覆于碳钢基材表面制备高耐温涂层。通过热重分析明确了漆酚钛涂层的耐温性能;利用高温、高压且含CO₂介质浸泡试验,通过形貌与傅里叶变换红外光谱分析评价了涂层在模拟盐水中对碳钢的防护性能;使用电化学阻抗谱（EIS）评价了浸泡前后涂层在腐蚀介质中的阻抗变化。结果表明：漆酚钛涂层的热分解温度高达275.19℃;在140℃与155℃的模拟盐水溶液（CO₂分压2 MPa）中浸泡30 d后,涂层的低频阻抗值分别达到10¹¹ Ω·cm²与10¹⁰ Ω·cm²数量级;涂层的价键特征未发生改变,表面形貌完整且与基材结合紧密,表现出优异的耐高温防护性能。     

高固体分环氧防腐蚀涂层/铝合金在模拟超深海高压环境下的防护行为研究

为了提高铝合金在深海环境中的防护性能,研制了一种铝合金深海防护用高固体分环氧防腐蚀涂料.采用电化学测试技术、盐雾加速试验和涂层形貌分析等手段研究了高固体分环氧防腐蚀涂层在模拟常压海水环境和超深海高压环境(36.0 MPa)下对铝合金的防护行为.结果 表明:高固体分环氧防腐蚀涂料在铝合金基材上的耐盐雾寿命达1000h以上,涂层在铝合金上的拉拔附着力为11.28～13.52 MPa,经36.0 MPa高压盐水浸泡35 d后的湿附着力为7.52～8.12 MPa.铝合金/涂层体系在超深海高压环境下,漆膜吸水导致涂层电阻降低及电容逐渐增大,浸泡35 d后,涂层低频阻抗模值降低到3.85×106 Ω·cm2;深海高压导致涂层中的颜填料疏松,容易形成腐蚀通道导致涂层破损和基体腐蚀.提高涂层在金属上的湿附着力和致密性,是延长涂层在深海环境下防护寿命的关键因素.     

纳米有机涂层在3.5%NaCl溶液中的电化学阻抗谱研究

纳米有机涂层防腐蚀性能良好,但目前有关其对金属防护的具体过程的研究却不多。将涂装纳米有机涂层的16MnR钢试样浸泡在3.5%的NaCl溶液中,采用电化学阻抗谱法(EIS)研究纳米有机涂层在试验周期360d不同测试时间的作用效果,分析各时段纳米有机涂层在NaCl溶液中对金属的防腐蚀情况。结果表明,纳米有机涂层体系对金属基体具有很好的保护性,其对金属的保护过程可以分为4个阶段:腐蚀介质渗入有机涂层阶段,腐蚀介质渗透到富锌涂层阶段,腐蚀产物形成阻挡层阶段,腐蚀产物填补孔隙阶段。     

利用LEIS和EIS研究铁红环氧酯底漆在海水介质中的失效行为

为了明确铁红环氧酯底漆在沿海潮湿环境中的劣化过程,采用局部电化学阻抗谱(LEIS)技术和电化学阻抗谱(EIS)技术研究了铁红环氧酯底漆在海水介质中干湿循环条件下的失效过程。结果表明:铁红环氧酯底漆在干湿循环条件下对Q345R钢的防护性能呈阶段性变化。在海水渗入初期,涂层表面随机分布大量的高阻抗点,涂层的防护性能与完好涂层相差很少;但在海水渗透涂层后,整体阻抗值明显降低,同时试样表面随机分布的高阻抗点数量有所减少,导致涂层防护性能发生明显下降,Q345R钢基材开始被腐蚀。     

Zn-Ni-V热浸镀层组织及腐蚀电化学行为研究

在锌浴中添加少量的Ni和V,获得了Zn-0.05%Ni-0.05%V镀层.研究了Zn-0.05%Ni-0.05%V镀层组织和在5%NaCl溶液浸泡过程中的腐蚀行为.结果表明:在Zn-0.05%Ni镀浴中添加0.05%V可以有效地抑制Fe-Zn反应,控制ζ相层的超厚生长.与Zn-0.05%Ni镀层相比,浸泡20min后,...     

Effect of Nano Clay on Corrosion Protection of Zinc-rich Epoxy Coatings on Steel 37

Epoxy zinc rich coatings containing clay nanoparticles were prepared and the effect of clay content on the cathodic protection performance of the coatings was evaluated by electrochemical impedance spectroscopy(EIS) and immersion test. Open circuit potential(OCP) measurements and immersion tests were also carried out to better understand the behavior of zinc rich coating. EIS and OCP measurements showed that addition of 1 wt% clay improved the cathodic protection duration and sacrificial properties of the epoxy zinc rich coating. Transmission electron microscopy(TEM) photographs confirmed that clay nanoparticles were successfully dispersed in the coating matrix loaded with 1 wt% clay. Immersion test results indicated that addition of 1 wt% clay nanoparticles in zinc rich epoxy coatings increased the cathodic protection ability of coatings.     

Protective Properties of High Temperature Oxide Films on Ni-based Superalloys in 3.5% NaCl Solution

The electrochemical behaviors of high temperature oxide film formed on the sputtered microcrystalline coating of M38 alloy （mc-M38） were investigated by potentiodynamic and electrochemical impedance spectroscopy （EIS） techniques in 3.5% NaCl solution. Mott-Schottky analysis was used to study the semi-conductive properties of the surface oxide. The results of the capacitance measurements showed that the oxide films on both the coating and the cast alloy were p-type semiconducting characteristics. Both the carrier density （Na）and the flat band potential （Efb） were obviously frequency-dependent, and the optimal frequency range was from 1000 to 1500 Hz. The oxidized coating exhibited higher protectivity than the oxidized cast alloy due to the lower carrier density compared with that of the oxidized cast alloy. The EIS data of the long-term immersing tests suggested that the oxide film served as an inner-barrier layer against chloride ions. The penetration of the aggressive ions into the surface oxide resulted in the decreased polarization resistance as a function of the immersion time.     

A mussel-inspired delivery system for enhancing self-healing property of epoxy coatings

Dopamine (DA),one type of mussel-inspired biological molecules with adhesive nature and corrosion inhibitor property,are often used to functionalize the surfaces of various materials.Herein,we report the application of polydopamine (PDA) microcapsules as novel nanocontainers for the purpose,loading corrosion inhibitor (benzotriazole) in its shell structure,and then were embedded into epoxy coatings to provide self-healing and anti-corrosion protection for carbon steel.Fast release of benzotriazole in acidic environment caused by local corrosion and the chelating effect of PDA-Fe3+ can synergistically promote the formation of protective film on bare steel surface,which endows coatings with self-healing func-tionality.Electrochemical impedance spectroscopy (EIS),local electrochemical impedance spectroscopy(LEIS),and spray tests were conducted to evaluate the active inhibition and corrosion resistance of the loaded coatings.The scratched coating with incorporation of nanocontainers presented better protection performance,exhibiting increased Ro (oxide layer resistance) and Rct (charge transfer resistance) during initial immersion periods.The EIS tests in long-term immersion were also performed to confirm the anti-corrosion effect of composited coatings.These results demonstrated that benzotriazole-decorated PDA capsules dramatically enhanced the self-healing properties and anti-corrosion performance of epoxy coatings with the synergistic help of PDA and benzotriazole.     

基于EIS研究镁水泥混凝土中涂层钢筋的耐腐蚀性

通过模拟室内自然状态、氯化镁溶液和水三种工作环境,采用CS350电化学工作站,结合理论与试验分析,对镁水泥混凝土涂层钢筋的交流阻抗谱进行研究。结果表明:通过对交流阻抗谱和涂层电阻的表征分析得出该涂层可以很好地保护镁水泥混凝土中的钢筋免受腐蚀。不同的混凝土保护层厚度对同时期的涂层电阻有一定的影响,涂层电阻的大小随保护层厚度增加而增加。从而得出该涂层对镁水泥钢筋混凝土中的钢筋起到很好的保护作用,进而解决镁水泥钢筋混凝土在盐渍土地区应用易受侵蚀的问题。     

Development and characterization of sol‐gel composite coatings on aluminum alloys for corrosion protection

For several years, Cr^IV compounds were used as effective and inexpensive corrosion inhibitors. Studies showed that these materials were toxic and carcinogenic. This has led to extensive research to develop alternative inhibitors. Organo‐silicate hybrid coatings appeared as an effective technique for forming protective layers on different metal alloys. A silane film was obtained by dip coating of the sample in sol solution prepared from the hydrolysis of 3‐glycidoxypropyltrimethoxysilane (GPTM), tetraethylorthosilicate (TEOS) with acid as catalyst and water as solvent instead of VOC (volatile organic compound). The sol solution was aged at ambient temperature to to enhance the effectiveness of the solution for the hydrolysis process. The sample was cured at 150 °C to ensure cross‐linking of the film. The experiments have shown that heat treatment leads to increased density and corrosion resistance of the films. Organic and inorganic inhibitors were added in different concentrations to improve the protection and self‐healing properties of the coating even after long‐time immersion in corrosive solution. The protection performance of the film was evaluated by electrochemical impedance spectroscopy (EIS) in 0.5 M NaCl solution (pH value 7). The surface morphologies of the treated samples were investigated using SEM.     

陈化对AZ91D镁合金上磷化膜的影响及磷化膜退化机制的研究

以磷酸盐化学转化膜为研究体系,采用交流阻抗(EIS)及红外(FT-IR)分析方法及检测手段,研究陈化时间对AZ91D镁合金磷化膜性能的影响及磷化膜的腐蚀退化机制.研究发现(1) EIS图谱和FT-IR图谱对比结果表明陈化时间对AZ91D磷化膜层性能有影响,磷化膜经陈化72h后更稳定.(2)磷化试样在硼酸缓冲液中浸泡实验的EIS测试表明,磷化膜的腐蚀退化机制分3个阶段:浸泡初期,中期和后期.浸泡初期(5～10h),电解质缓慢向磷化膜渗入,且有少量电解质浸入内层界面;浸泡中期(30～70h),随着内层界面腐蚀反应的发生,腐蚀产物开始对外层晶体层产生破坏作用,使缺陷扩大,导致电解质开始大量进入到内层界面;浸泡后期(80～120h),内层腐蚀反应达到平衡,膜层电阻等各项参数不再改变.     

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。