环氧富锌/环氧煤沥青涂层在原油罐底沉积液中失效过程的EIS研究

采用环氧富锌涂料作为底漆,环氧煤沥青重防腐涂料作为面漆,研究了该涂层体系在原油罐底沉积液中失效过程的电化学阻抗谱(EIS)的变化,并提出相应腐蚀阶段的等效电路,讨论了阻抗谱的特征变化与涂层体系结构及性能变化的关系。结果表明,从EIS特征可以反映出涂层体系所处的腐蚀阶段,提出的判断方法可为罐底防腐蚀涂层的失效研究和维修维护提供参考。     

环氧富锌涂层防腐蚀性能研究

制备了添加纳米SO2材料的纳米复合环氧富锌涂层,通过测试金属Zn含量、拉开法附着力、浸泡实验、盐雾实验和电化学阻抗谱实验,并与两种未添加纳米材料的环氧富锌涂层防腐蚀性能进行对比研究,结果表明,纳米复合环氧富锌涂层具有良好的附着力和内聚力,前期可以作为有机屏蔽层,中期阴极保护作用温和,持续时间长,后期Zn的反应产物又可以提供涂层良好的屏蔽,耐腐蚀性能显著,而未添加纳米材料的两种富锌涂层由于起泡和锈蚀而失效。     

电化学阻抗谱研究三种涂层体系的耐蚀性

为选择某型特种装备的表面防腐蚀涂层,利用电化学阻抗谱对H06-4环氧富锌/H53-13环氧云铁/丙烯酸聚氨脂、环氧富锌/厚膜灰云铁环氧/TB06-42丙烯酸聚氨脂和环氧防锈平整底漆/CE-46环氧/丙烯酸聚氨脂三种涂层体系进行了耐蚀性评价测试。结果表明,随着浸泡时间的延长,三种涂层体系的保护作用都降低。对比涂层的阻抗谱变化特征得知,H06-4环氧富锌/H53-13环氧云铁/丙烯酸聚氨脂涂层体系耐蚀性较佳,因此被选为某型装备用防腐蚀涂层。     

硅烷偶联剂处理对富锌涂层行为的影响

 采用测量涂层的腐蚀电位和电化学阻抗谱(EIS)等方法研究了硅烷偶联剂处理(钢铁表面的硅烷偶联剂预处理和富锌漆中掺入硅烷偶联剂)对富锌涂层在3.5mass%NaCl溶液中腐蚀行为的影响.结果表明，两种硅烷处理方式均明显延长了富锌涂层的阴极保护期.钢铁表面硅烷处理减弱了无机富锌涂层的阴极保护作用.      

改性氧化石墨烯基环氧富锌涂层的防腐蚀性能

目的 通过添加改性氧化石墨烯,提高环氧富锌涂层的防腐性能.方法 采用对氨基苯磺酸重氮盐、聚乙烯吡咯烷酮(PVP)以及磺化碳纳米管(SMWCNT)作为改性剂,分别对氧化石墨烯(GO)进行改性处理,并制备改性氧化石墨烯基环氧富锌涂层.采用X-射线衍射谱、傅里叶红外转换光谱和扫描电镜,分析了GO改性前后的结构变化和在涂层中的分散效果.选择改性效果最佳的氧化石墨烯基环氧富锌涂层,并通过电化学交流阻抗谱、盐雾试验、扫描电镜和开路电位等手段分析涂层在腐蚀环境中的腐蚀行为,测试其耐腐蚀性能.结果 三种改性GO被成功制备,片层分散效果均得到提升,其中经SMWCNT改性后,GO的片层间距由0.83 nm变为0.88 nm,且在涂层中的分散效果最佳,形成的涂层致密无孔隙.加入改性氧化石墨烯后,环氧富锌涂层的阴极保护时间得到延长,物理屏蔽作用得以增强.在盐雾试验1680 h后,涂层表面完整无起泡现象,金属基底腐蚀坑的最大坑深由42.31μm降至16.09μm.涂层在电解质溶液的浸泡过程中均表现出比纯环氧富锌涂层更高的阻抗模量,且在浸泡72 d后,涂层的低频阻抗值由103?·cm2提升到104?·cm2,耐蚀性能优于纯环氧富锌涂层.结论 环氧富锌涂层中添加改性石墨烯后,防腐性能提升了62.4％.     

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。     

Influence of the Pigment Shape on the Electrochemical Behaviors of Zinc—Rich Paint Coatings in 3.5% NaCl Solution

针对粘合剂种类、Zn粒形状和涂层厚度的协同作用，采用电化学阻抗谱(EIS)研究了富Zn涂层在3．5％NaCl溶液中的电化学行为．富Zn涂层的EIS谱有两个时间常数，其中，锌的电子转移反应发生在低频段，而高频段则体现聚合物和Zn表面氧化层的介电性质．根据等效电路及其元件参数解释了钢铁／富Zn涂层／盐水体系的EIS测量结果．实验结果表明，鳞片锌消耗速度太快以至于鳞片富Zn涂层在相对较短的时间内就失去了阴极保护作用，随后形成了稍微致密的屏蔽阻挡层。     

有机覆膜对热烧结锌铝涂层耐腐蚀性能的影响

为提高热烧结锌铝涂层（简称锌铝涂层）的耐蚀性,在涂层表面涂覆一层环氧富铝膜,形成复合涂层。采用十字划格法测试锌铝涂层和复合涂层的附着强度,并用扫描电镜（SEM）分析涂层微观形貌;用海水全浸实验和中性盐雾实验评价涂层的耐蚀性能;采用动电位极化曲线和电化学阻抗谱（EIS）研究涂层的电化学性能。结果表明,复合涂层表面更为完整致密,防水性能优于锌铝涂层;环氧富铝膜层能够有效的阻挡腐蚀介质的入侵,复合涂层耐蚀性比锌铝涂层高。复合涂层腐蚀初期主要为扩散控制,随着腐蚀介质的不断渗入,环氧膜层中的Al粉发生活化反应,起到了一定的牺牲阳极保护作用。有机覆膜提高了锌铝涂层在海洋环境中的适用能力。     

通过8-羟基喹啉改性提高环氧富锌涂层的保护性能

利用电化学阻抗、红外光谱、电镜等方法研究了8-羟基喹啉改善环氧富锌涂层性能的作用。在环氧富锌涂层中用5%的8-羟基喹啉替代锌粉后,锌粉溶解反应的电荷转移电阻Rct增加,且锌粉/溶液界面双电层电容Qdl降低,表明锌粉的反应过程被抑制,因此,虽然涂层中锌粉的含量有所降低,但是锌粉的阴极保护作用时间却明显延长。另一方面,8-羟基喹啉改性后的环氧富锌涂层的电阻Rc升高,电容Qc降低,涂层孔隙率P降低,涂层的屏蔽性增强。上述两方面的作用,可以显著改善涂层的保护性能,延长涂层寿命。     

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。     

Study on corrosive electrochemical behaviors of zinc‐rich and graphite‐filled epoxy coatings in 3.5 wt% NaCl solution

Environment behaviors and degradation mechanisms of two organic epoxy coatings coated on carbon steel sheets in 3.5 wt% NaCl neutral solution were studied by electrochemical impedance measurements and atomic force microscopy (AFM). The results showed that the coating resistance (R_p) of the graphite‐filled epoxy coating tested, which presents the film barrier performance, is higher than those of 6101 epoxy resin for initial seawater immersion, but the coating resistance of the zinc‐rich epoxy coating was lower than that of 6101 epoxy resin. After salt spray tests, zinc‐rich epoxy coating coated on the metal still has good anti‐corrosion performances due to the existence of protection effects called “electrochemical” and “chemical” protection. Those behaviors and degradation mechanisms of two coatings can be explained by a series of measured electrochemical impedance spectroscopy measurements, and two equivalent circuit models were proposed to explain the degradation processes of the two organic coatings.     

Application of EIS and SEM to evaluate the influence of pigment shape and content in ZRP formulations on the corrosion prevention of naval steel

The effects of pigment volume concentration and morphology of zinc particles employed in the formulation of zinc rich paints (ZRP) suitable for the corrosion protection of naval steel in sea water, have been investigated using electrochemical impedance spectroscopy combined with open circuit potential measurements and SEM micrograph analysis. Different ZRP samples were tested during exposure to artificial sea water for up to 70 days. The characteristics and properties of the naval steel/ZRP coating/sea water systems were determined from an impedance transfer function model which involves the reactions occurring at the metal/ZRP and ZRP/solution interfaces as well as diffusion processes through the active ZRP coating. Information concerning the influence of concentration and shape of the zinc pigment on the corrosion protective behaviour of ZRP coatings and on the exposure time dependence of the system parameters allowed to interprete the form in which the galvanic action and the barrier effect diminish progressively. The degree of rusting of the steel substrates as well as the blistering resistance of the formulated ZRP have been also evaluated according to conventional ASTM standards.     

Electrochemical behavior of organic and inorganic zinc-rich coatings in 3.5% NaCl solution

1　INTRODUCTIONZinc richcoatings (ZRP)havebeenusedformanyyearsinordertoprotectsteeleffectivelyinag gressiveatmospheres ,mainlyinmarineandindustrialenvironments,againstcorrosion .ItiscommonlyacceptedthattwofundamentalprotectionmechanismsoperateinZRP[13] :1)thegalvanicprotectionstage ,whichrequires goodelectricalcontactamongthezincparticlesthemselvesaswellasbetweenthemandthesteelsubstrate ;2 )thebarrier likebehaviorstage ,whichisreinforcedbytheamountandnatureofzinccorrosionproductslead ing…     

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...     

Effect of molybdate post-sealing on the corrosion resistance of zinc phosphate coatings on hot-dip galvanized steel

The technique of post-sealing the phosphated hot-dip galvanized (HDG) steel with molybdate solution was addressed. The composition and corrosion resistance of the improved phosphate coatings were investigated by SEM, EDS, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements, and neutral salt spray (NSS) test. The results showed that molybdate films were formed in the pores of phosphate coatings, and the compact and complete composite coatings composed of phosphate coatings and molybdate films were formed on the zinc surface, resulting in that both the anodic and cathodic processes of zinc corrosion were inhibited remarkably; the corrosion protection efficiency values were increased; and the electrochemical impedance values were enhanced at least one order of magnitude. The low frequency impedance values for the composite coatings were increased at the initial stages of immersion in 5% sodium chloride solution, indicating the self-repairing activity of the composite coatings.     

涂料中含铬量对烧结式富锌涂层性能的影响

以片状锌粉和铝粉为原材料 ,研究了涂料中铬酐含量对烧结式富锌涂层性能的影响。结果表明 :涂料中的铬酐含量决定涂层中金属粉的粘结情况 ,铬酐含量过高 ,涂层局部爆皮 ;铬酐含量过低 ,涂层粉化。在得到粘结性好的涂层范围内 ,铬含量越高 ,涂层耐蚀性越好。     

Corrosion study of Ni/Zn compositionally modulated multilayer coatings using electrochemical impedance spectroscopy

Ni/Zn compositionally modulated multilayer (CMM) coatings were deposited using dual bath technique. Coatings corrosion performance was evaluated using electrochemical impedance spectroscopy (EIS) during extended immersion times up to 48 h. The results of electrochemical impedance spectroscopy showed that Ni/Zn CMM coatings had better corrosion resistance compared to that of the zinc single layer coating. The modified corrosion product which is formed on the Ni/Zn CMM coatings during extended exposure times and also a good barrier effect of the nickel layer against aggressive species in these coatings can be two important reasons for high corrosion performance and so protection performance of the Ni/Zn CMM coatings.     

Novel zinc‐rich epoxy paint coatings with hydrated alumina and carbon nanotubes supported polypyrrole for corrosion protection of low carbon steel: Part II: Corrosion prevention behavior of the hybrid paint coatings

Utilization of various types of multi‐walled carbon nanotubes (MWCNTs) in zinc‐rich paints (ZRPs) is presented addressing percolation and porosity related phenomena of traditional ZRPs. Hybrid paint coatings were formulated with 3.21 wt% polypyrrole (PPy) deposited alumina‐MWCNT inhibitor particles (PDAMIPs) and 70 wt% zinc contents. Corrosion protection behavior of the hybrid coatings was investigated by electrochemical impedance spectroscopy (EIS), glow‐discharge optical emission spectroscopy (GD OES), X‐ray photoelectron spectroscopy (XPS), and FT‐Raman spectroscopy. Immersion and salt‐spray chamber tests gave evidence of improved galvanic protection and barrier nature of the hybrid coatings over the conventional ZRPs, whereas inhibited zinc corrosion and ignorable steel corrosion took place besides lower degradation of the binder. Zinc‐rich hybrid paints with either high relative amount of polyelectrolyte‐modified or low proportion of functionalized MWCNTs afforded enhanced corrosion prevention. This result is partly attributed to the nanotube volume fractions around the threshold of infinite cluster formation contributing to electrical percolation and galvanic action of the hybrids. Experimental results are discussed in a broader context on the basis of structure related findings of the PDAMIPs (described in Part I) and in the light of recent literature data. From the newly developed inhibitor particles, some of them are respected as worthy additives for application in hybrid coatings featuring high performance corrosion prevention functionality.     

The mechanism of inhibition by zinc phosphate in an epoxy coating

Epoxy coatings containing different volume fractions of zinc phosphate have been successfully prepared and their inhibitive properties have been studied by electrochemical impedance spectroscopy (EIS) and immersion tests. The results show that zinc phosphate can improve the protection ability of epoxy coatings and its best volume fraction is 30%. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) results indicate that the presence of zinc phosphate can form an inhibiting film which is composed of the phosphating film of FePO₄, Fe₂O₃, and FeO, as well as the shielding film of zinc phosphate on the steel surface.