电化学方法研究环氧防锈涂料实验室实验与实海环境实验的相关性

用电化学交流阻抗法(EIS)研究了环氧防锈涂料在实海浸泡实验和3.5%NaCl溶液浸泡实验、盐雾实验、湿热实验3种实验室加速实验中的失效行为,探讨了实海浸泡实验和3种实验室加速实验的|Z|_(0.01 Hz)对应关系。结果表明:4种腐蚀环境对所研究的涂层体系的破坏作用由小到大依次为:3.5%NaCl溶液实海浸泡湿热盐雾;相对实海浸泡实验,盐雾实验对环氧涂层腐蚀失效的加速因子约为2.3。     

无机/有机复合涂层体系在3.5%NaCl溶液中的EIS

采用电化学阻抗谱（EIS）研究了无机富锌底漆/环氧云铁中间漆/氯化橡胶面漆复合涂层体系在3.5%NaCl溶液中的腐蚀电化学行为，考察了紫外辐射对其电化学行为的影响。结果表明：复合涂层体系在3.5%NaCl介质中的腐蚀失效过程可以用4种等效电路来等效。浸泡失效前120 h，电解质溶液电阻R_c从开始的5×10⁹ Ω·cm²以大约2.2×10⁷ Ω·h^-1的速度迅速下降到4×10⁵ Ω·cm²，到浸泡120 h后R_c则以较小的速度808 Ω·h^-1下降，涂层电容C_c是按线性增加。紫外辐射不改变复合涂层体系在3.5% NaCl溶液中的电化学行为，仅仅加速复合涂层的失效。     

不同加速试验对环氧/聚氨酯涂层失效机制的影响

研究了模拟南海海洋大气环境下铝合金表面环氧锌黄/丙烯酸聚氨酯涂层体系的失效过程,通过循环加速、紫外/冷凝和中性盐雾的对比试验,探讨了在循环加速试验中紫外-冷凝试验和盐雾试验分别对复合涂层失效过程以及对聚氨酯面漆和环氧底漆失效机制的影响。结果表明,紫外-冷凝过程对丙烯酸聚氨酯面漆有较强的破坏作用,但对复合涂层体系整体的阻抗变化影响较小;紫外-冷凝过程中,位于面漆玻璃化转变温度范围内的试验温度,以及紫外光对氨基甲酸酯基团的破坏作用,是导致面漆发生破坏的主要原因。盐雾试验对面漆的失光率和色差变化影响不大,但连续的盐雾渗透对涂层体系的阻抗下降具有明显的加速作用,同时导致涂层与基材的附着力显著降低。相比单独的紫外-冷凝试验或盐雾试验,循环加速试验综合考虑了南海海洋大气中强太阳辐射、高温高湿、高盐分和温差等环境因素,能更准确反映南海大气环境中复合涂层的失效过程。     

不同加速试验对环氧/聚氨酯涂层失效机制的影响

研究了模拟南海海洋大气环境下铝合金表面环氧锌黄/丙烯酸聚氨酯涂层体系的失效过程,通过循环加速、紫外/冷凝和中性盐雾的对比试验,探讨了在循环加速试验中紫外-冷凝试验和盐雾试验分别对复合涂层失效过程以及对聚氨酯面漆和环氧底漆失效机制的影响。结果表明,紫外-冷凝过程对丙烯酸聚氨酯面漆有较强的破坏作用,但对复合涂层体系整体的阻抗变化影响较小;紫外-冷凝过程中,位于面漆玻璃化转变温度范围内的试验温度,以及紫外光对氨基甲酸酯基团的破坏作用,是导致面漆发生破坏的主要原因。盐雾试验对面漆的失光率和色差变化影响不大,但连续的盐雾渗透对涂层体系的阻抗下降具有明显的加速作用,同时导致涂层与基材的附着力显著降低。相比单独的紫外-冷凝试验或盐雾试验,循环加速试验综合考虑了南海海洋大气中强太阳辐射、高温高湿、高盐分和温差等环境因素,能更准确反映南海大气环境中复合涂层的失效过程。     

利用EIS高频区参数评价两种环氧涂层的性能

利用10 kHz下的相位角、10 kHz下的相对介电常数和对应于45°相位角的特征频率这3种EIS高频区的参数对两种环氧涂层体系在盐水浸泡+紫外照射的腐蚀条件下的失效过程进行了表征,并与涂层阻抗值进行了对比。测量结果表明,上述3种高频区参数的结果一致,都能够反映涂层性能的变化及相对优劣。当频率10 kHz处的相位角下降到40°,相对介电常数增大到40,或特征频率接近10 kHz时,所研究的两种环氧涂层体系的阻抗值都对应降低到10⁶ Ω•cm²左右,涂层保护性能接近失效。由于这几种EIS高频区参数能够很快测得,因此可以利用这些参数快速评价该涂层的保护性能与失效程度。     

铝粉对醇溶性无机富锌漆性能的影响

研究了醇溶性无机富锌漆中球状锌粉质量的5％、10％、15％、20％、25％和30％被铝粉取代对涂层性能的影响.通过开路电势-时间曲线研究了涂层在3.5％ NaCl溶液中电化学活性的变化情况,同时记录了涂层的耐盐水浸泡时间;采用盐雾试验研究了涂层的耐盐雾时间.结果显示:涂层的耐盐水和耐盐雾时间随取代比增加都是先延长后缩短...     

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。     

氧化锌对醇溶性无机富锌漆性能的影响

研究了醇溶性无机富锌漆中球状锌粉被氧化锌粉取代对涂层性能的影响.通过电位-时间曲线研究了涂层在3.5％NaCl溶液中电化学活性的变化情况,同时记录了涂层的耐盐水时间,耐盐雾时间.结果显示:随氧化锌的增加涂层的耐盐水和耐盐雾时间均都是先延长后缩短,在w(氧化锌)为15％时达到最大值.涂层的阴极保护时间呈现同样的规律.     

环氧带锈涂层在干湿交替环境中失效过程的电化学阻抗谱

应用电化学阻抗谱(EIS)技术研究了浸泡在3.5%NaCl溶液中的环氧带锈涂层在干湿交替条件下的劣化过程。结果表明,干湿交替环境下环氧带锈涂层的阻抗变化与全浸环境类似,表现为3个阶段:阻抗迅速降低阶段,缓慢降低阶段和最后的失效阶段,但干湿交替环境中涂层阻抗值比全浸环境要低两个数量级,涂层电容则约高一个数量级,涂层失效速率明显高于全浸泡环境下的失效速率。环氧带锈涂层在干湿交替环境下的失效原因,主要可归因于干湿交替循环使涂层发生溶胀与收缩,增加了涂层的孔隙率;此外,干湿交替状态也会促进氧向涂层/金属界面的渗透,从而加速基体金属的腐蚀并加快涂层的失效过程。     

盐雾对环氧涂层防腐蚀性能影响的电化学研究

制备了新型环氧富锌、环氧铁红、环氧云铁3种有机涂层材料。在此基础上，采用交流阻抗技术，对各种环氧涂层在盐雾前后进行了阻抗谱测定，并研究了涂层在盐雾环境中的失效机理。结果表明：3种涂层材料在盐雾实验后，阻抗圆直径均大幅减小，涂层耐腐蚀性能较盐雾前降低。盐雾实验后各涂层的耐腐蚀性能由强到弱依次是环氧云铁、环氧铁红、环氧富锌。通过对盐雾实验前后涂层阻抗谱的分析，比较了几种涂层材料的性能，提出了可能的腐蚀破坏机制。     

The failure behavior of a polyurethane composite coating in 3.5% NaCl solution under ultraviolet irradiation

The failure process of inorganic zinc‐rich/micaceous iron oxide epoxy/aliphatic polyurethane composite coating in 3.5% NaCl solution under ultraviolet irradiation (UV) was studied with electrochemical impedance spectroscopy (EIS) and Fourier transform infrared (FTIR) spectroscopy. UV irradiation significantly accelerated failure process of the composite coating in NaCl solution. The effect of UV on failure process of the coating system in 3.5% NaCl solution may be divided into two stages: in the early stage, the thermal effect generated by the ultraviolet irradiation is the main reason leading to the increase in coating porosity, but this effect is not serious and the coating remains high impedance and good protection ability. In the latter stage, the fracture of polymer chains in the top coating by UV irradiation is the main factor resulting in quick decrease of coating performance. C N and C O bonds in polyurethane coating are broken by UV irradiation, leading to quick increase of the coating porosity and decrease of the coating resistance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

咪唑啉季铵盐缓蚀剂改性蒙脱土/水性环氧纳米复合涂料

以油酸、二乙烯三胺和氯化苄为原料,合成了油酸基咪唑啉季铵盐缓蚀剂。通过FTIR、¹HNMR对其结构进行了表征,并离子交换至钠基蒙脱土(DK0)层间,制备了缓蚀剂改性蒙脱土(QACDK0)。通过XRD、TGA和UV-Vis对其结构、组成及层间缓蚀剂释放性能进行了表征。结果表明,咪唑啉季铵盐缓蚀剂约占QACDK0质量的38.96%,并将蒙脱土层间距由1.28 nm(DK0)扩大至3.98 nm(QACDK0)。利用DLS及Zeta电位对添加有QACDK0的水性环氧树脂进行了稳定性测试,其Zeta电位为–27.8 m V,具有较高的稳定性。电化学阻抗谱(EIS)测试表明,在腐蚀介质中浸泡30 d后,基于QACDK0制备的清漆漆膜仍具有2.29×10⁸?·cm²的高阻抗,表明涂层具有较好的耐腐蚀性。并且在耐中性盐雾测试中,QACDK0对应的防腐色漆耐盐雾时间最长,验证了该涂层具有良好的耐盐雾性能。     

Studying the influence of nano-Al2O3 particles on the corrosion performance and hydrolytic degradation resistance of an epoxy/polyamide coating on AA-1050

The aim of this work was studying the effects of addition of Al₂O₃ nanoparticles on the anticorrosion performance of an epoxy/polyamide coating applied on the AA-1050 metal substrate. For this purpose, the epoxy nanocomposites were prepared using 1, 2.5 and 3.5 (w/w) pre-dispersed surface modified Al₂O₃ nanoparticles. Field-emission electron microscope (FE-SEM) and ultraviolet–visible (UV–Vis) techniques were utilized in order to evaluate the nanoparticles dispersion in the epoxy coating matrix. The anticorrosion performance of the nanocomposites was studied by electrochemical impedance spectroscopy (EIS) (in 3.5 wt% NaCl solution for 135 days immersion) and salt spray test for 1000 h. The coating resistance against hydrolytic degradation was also studied by optical microscope and Fourier-transform infrared spectroscopy (FTIR). Results obtained from FE-SEM micrographs and UV–visible spectra showed that the nanoparticles dispersed in the coating matrix uniformly with particle size less than 100 nm even at high loadings. Results revealed that nano-Al₂O₃ particles could significantly improve the corrosion resistance of the epoxy coating. Nanoparticles reduced water permeability of the coating and improved its resistance against hydrolytic degradation.     

Corrosion protection of mild steel by nano-colloidal polyaniline/nanodiamond composite coating in NaCl solution

The polyaniline/nanodiamond (PANI/ND) nanocomposite coating was synthesized on mild steel via electrochemical polymerization using cyclic voltammetry technique. The ultrasonic irradiation was used for effectively dispersing ND particles in electropolymerization solution. The prepared nanocomposite films were found to be nano-colloidal, and very adherent with low porosity. X-ray diffraction and FTIR techniques confirmed the intercalation of the nanoparticles in PANI matrix. The corrosion performance of the coatings was investigated in 3.5% NaCl solution by electrochemical impedance spectroscopy (EIS), polarization, and salt spray methods. The obtained results showed that the presence of ND particles significantly enhanced the corrosion protection performance of the PANI films in corrosive medium. EIS and polarization measurements indicated that the coating resistance and corrosion resistance values for the PANI/ND nanocomposite coating were much higher than that of pure PANI-coated electrode. Also, the results obtained revealed that the protection efficiency of PANI/ND-coated mild steel is achieved about 90% after 3 days. The porosity in PANI/ND nanocomposite coating is almost 18 times lower than that of the PANI coating.     

Effect of zinc oxide in combating corrosion in zinc-rich primer

During the production of zinc pigments, some zinc may get oxidized and remains as impurity. In the present study, the effect of spherical ZnO on corrosion protection properties was evaluated along with lamellar zinc. ZnO was added in various weight fractions in epoxy primer coating at 60% PVC. The coated panels were evaluated among others for their conductance, packing density and morphology. The corrosion resistance was measured using salt spray test for 3000 h of exposure. Open circuit potential (i.e. corrosion potential) was measured in 3.5 wt.% NaCl salt solution. The best corrosion protection was obtained with 15 wt.% of ZnO.     

Studying the effects of micro and nano sized ZnO particles on the corrosion resistance and deterioration behavior of an epoxy-polyamide coating on hot-dip galvanized steel

The effects of micro and nano sized ZnO particles on the corrosion resistance and hydrolytic degradation of an epoxy coating were studied. Different analytical techniques including scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), dynamic thermal mechanical analysis (DMTA) and nano-indentation were utilized to evaluate the hydrolytic degradation as well as the corrosion resistance of the coatings in exposure to 3.5 wt% NaCl solution. It was found that the epoxy coating resistance against corrosive electrolyte was significantly improved using nano and micro sized ZnO particles. The corrosion resistance of the nanocomposite was considerably greater than the one reinforced with the micro-ZnO particles. Moreover, the resistance of the coating reinforced with the nano sized particles against hydrolytic degradation in exposure to the corrosive electrolyte was considerably greater than the one reinforced with the micro sized particles. Decrease in both nano hardness and cross-linking density of the epoxy coating reinforced with nanoparticles after exposure to the corrosive electrolyte were considerably lower than the blank sample and the sample reinforced with the micro sized ZnO particles. Using nano sized particles the coating adhesion loss decreased.     

Expression of the transportation of corrosive media into epoxy coating using nano-indentation

Nano-hardness (H_nano) and nano-elastic modulus (E_nano) of corroded coating surface layer were investigated using nano-indentation after epoxy coated specimens were immersed in 5% NaCl solution. The penetration depths (d) of corrosive media into epoxy coating were calculated fitting the curves of (H/E)_nano vs. indentation depth (h). EIS spectra of epoxy coated specimens immersed in 5% NaCl solution for different time were measured. Finally the relationship of capacitance (C_f,T) of corroded epoxy coating with the penetration depth of corrosive media was studied. The experimental results showed that the transportation process of corrosive media into epoxy coating was studied through the profiles of (H/E)_nano with indentation depth. The penetration depth of corrosive media into the epoxy coating increases rapidly with immersed time firstly, and then increases slowly. The capacitance of corroded epoxy coating has a linear function relationship with the penetration depth of corrosive media into epoxy coating. Nano-indentation can be used to study the transportation process of corrosive media into organic coating.     

Corrosive wear behavior of HVOF-sprayed micro-nano-structured Cr3C2–NiCr cermet coatings under aqueous media

A novel micro-nano-structured Cr₃C₂–NiCr cermet coating was prepared on 316L stainless steel by high-velocity oxygen fuel spraying technology (HVOF). Cermet coatings with different contents of micro-and nano-sized Cr₃C₂ particles as the hard phase and a NiCr alloy matrix as the bonding phase were prepared and characterized in terms of porosity, microhardness, and corrosive wear resistance in a 3.5% NaCl solution and artificial seawater. Compared to nanostructured coatings, micro-nano-structured coatings avoid decarburization and reduce nanoparticle agglomeration during the spray process, and mechanical and electrochemical properties were improved in comparison with those of conventional coatings. The micro-nano-structured Cr₃C₂–NiCr coating rendered low porosity (≤0.34%) and high microhardness (≥1105.0HV_0.3). The coating comprising 50% nano-sized Cr₃C₂ grains exhibited the best corrosive wear resistance owing to its densest microstructure and highest microhardness. Furthermore, compared to static corrosion, the dynamic corrosion of the coatings led to more severe mechanical wear, because corrosion destroyed the coating surface and ions promoted corrosion to invade coatings through the pores during corrosion wear.     

Investigation of corrosion protection properties of an epoxy nanocomposite loaded with polysiloxane surface modified nanosilica particles on the steel substrate

In this study, it has been aimed to investigate the corrosion protection properties of an epoxy/polyamide coating loaded with different concentrations (ranged from 3 to 6% (w/w)) of the polysiloxane surface modified silica nanoparticles (nano-SiO₂). The nanocomposites were applied on the steel substrates. Field emission scanning electron microscope (FE-SEM) and UV–vis techniques were utilized in order to investigate the nanoparticles dispersion in the coating matrix. The effects of addition of nanoparticles on the corrosion resistance of the coating were studied by an electrochemical impedance spectroscopy (EIS) and salt spray test. The coating surface degradation was studied by optical microscope and Fourier transform infrared radiation (FT-IR) spectroscopy. Results obtained from UV–vis and FE-SEM analyses revealed proper and uniform distribution of surface modified nanoparticles in the epoxy coating matrix. It was shown that the coating corrosion protection properties were significantly enhanced in the presence of 5 wt% silica nanoparticles. Less degradation occurred on the surface of the coatings loaded with 5 wt% nanoparticles.