Development of novel waterborne poly(1-naphthylamine)/poly(vinylalcohol)–resorcinol formaldehyde-cured corrosion resistant composite coatings

Advancements in the field of corrosion protective coatings have headed towards the utilization of conducting polymer-based blends and composites for the formulation of corrosive protective paints and coatings. With the aim to develop an ecofriendly waterborne conducting polymer-based protective coating material, corrosion protective behavior of waterborne resorcinol formaldehyde (RF)-cured composite coatings of poly(1-naphthylamine) (PNA)/poly(vinylalcohol) (PVA) was investigated on mild steel (MS). The corrosion protective performance was evaluated by physicochemical, physicomechanical, corrosion protective efficiency and resistance in acid, alkaline and saline media by open circuit potential (OCP) measurements. The morphologies of coated, uncoated as well as corroded samples were analyzed by SEM technique. Superior corrosion protective performance was observed which was compared to the reported solvent-based conductive polymer coatings in different corrosive media.     

Electroactive polymer films for stainless steel corrosion protection

Electroactive polymer films of polyaniline, poly-o-toluidine and a composite of both were deposited on stainless steel and their performance as protective coatings against corrosion was evaluated. Open circuit potential and potentiodynamic studies of the polymer-coated stainless steel in a corrosive medium showed a significant shift in the corrosion potential towards more positive values. Mechanical characteristics of the films were evaluated by means of microhardness measurements, revealing nonelastic films in all cases and low hardness values that increased from polyaniline to poly-o-toluidine to the composite. The best results were obtained in the case of the polyaniline-o-toluidine composite.     

Urushiol titanium polymer-based composites coatings for anti-corrosion and antifouling in marine spray splash zones

Seawater is highly corrosive, and the alternating dry and wet environment can cause severe corrosion in metal equipment. Moreover, marine equipment is also seriously affected by marine biofouling. These harsh conditions pose a serious threat to the integrity of marine equipment as well as their associated maritime activities and necessitate the development of effective coatings to minimize damage to the equipment. Urushiol titanium polymer/acrylic resin (UTP/AR) composite materials were developed. Then, marine anti-corrosion and antifouling coatings were prepared from the UTP/AR composite materials using rosin-modified Cu₂O as an antifoulant. The composite coating with a UTP:AR mass ratio of 1:1 (UTP/AR3) showed the best chemical resistance and light aging resistance. UTP/AR3 also exhibited a good corrosion current density (2.009 × 10⁻⁷ A cm⁻²) and corrosion potential (−0.5007 V), further indicating that the UTP/AR composite coatings have excellent anti-corrosive properties. Marine field tests showed that the UTP/AR/Cu₂O composite coatings with rosin-modified Cu₂O contents less than 20% showed stable, long-term antifouling performance after immersion in seawater for 360 day. Briefly, the UTP/AR/Cu₂O composite coatings have broad application prospects in the marine industry for materials in the spray splash zone.     

Bacterial exopolysaccharides for corrosion resistance on low carbon steel

Corrosion is a global issue that affects safety and economics. There is an increasing demand for bio‐based polymers for industrial applications and production of polymers by micro‐organisms is especially attractive. This work reports on the electrochemical and physical properties of exopolysaccharides produced from lactic acid bacteria and their suitability as anti‐corrosive coatings. Bacterial exopolysaccharide coatings protected low carbon steel from corrosion by reducing ionic diffusion rates and maintaining a relatively passive metal‐coating interface. The data suggest the kinetics of film deposition are fast (<5 min) and there is little excess (loosely bound) material when hydrated. Measurements show thin (50 nm) coatings that when exposed to water exhibit self‐repairing phenomenon. The corrosion protection offered by the coatings is reported as the corrosion rate calculated from the corrosion current obtained by electrochemical impedance and polarization spectroscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45032.     

Tribological and corrosion performance of epoxy resin composite coatings reinforced with graphene oxide and fly ash cenospheres

In this work, a novel graphene oxide (GO)-fly ash cenospheres (FACs) hybrid fillers was introduced to improve the wear and corrosive resistance of epoxy resin (ER) composite coatings. The tribological behavior and the corrosion performance of three kinds of coatings (pure ER, GO/ER and GO-FACs/ER coatings) were studied and the reinforced mechanisms of coatings filled by different fillers were analyzed. The friction coefficient and wear rate of the ER coatings were decreased with the addition of GO-FACs hybrids. The scanning electron microscope images showed that the dispersibility and compatibility of GO-FACs hybrids were effectively improved compared with that of GO sheet. The water contact angle examination indicated that the hydrophobicity of the GO-FACs/ER coatings increased. The electrochemical impedance spectroscopy (EIS) results demonstrated that the GO-FACs/ER coatings have better anticorrosion performance compared with the pure ER coatings and the GO/ER coatings. The hydrophobic surface and the well dispersed fillers constitute the dual barrier to resist the corrosion medium.     

Enhancement of adhesion,mechanical strength and anti-corrosion by multilayer superhydrophobic coating embedded electroactive PANI/CNF nanocomposite

Traditional insulative coatings usually suffer from pitting corrosion in harsh corrosive environment. Herein, in this work, electroactive polyaniline/carboxylated carbon nanofiber (PANI/CNF) nanocomposite was prepared via in situ chemical polymerization and first incorporated into superhydrophobic coating with better barrier effect. Multilayer coatings were constructed by facial spraying using polyphenylene sulfide (PPS) and ethylene tetrafluoroethylene (ETFE) with gradient weight ratios as film-forming materials. The composite coating with 40 wt% ETFE in top layer (denoted as ETFE-40) possesses best superhydrophobicity and highest oleophobicity with water contact angle (CA) and glycerol CA of 160° and 155° as well as low water sliding angle (SA) and glycerol SA of 2.2° and 8.8°, respectively. The lotus-like nano/micro structures, low surface energy material ETFE and modification of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS) should contribute to the superior liquid repellency. Especially, robust mechanical strength and durable anti-wettability are obtained with high WCA of 151° and glycerol CA of 147° after 8000 cycles abrasion. The composite coating also exhibits strong adhesion and superior self-cleaning. The enhanced electrochemical corrosion resistance of the coating in 3.5 wt% NaCl solution can be attributed to the outstanding barrier function of superhydrophobic surface and the passivation effect of electroactive PANI/CNF. This novel and effective coating system would definitely benefit the development of robust protective coating and promise wider engineering application.     

The influence of aluminium surface pretreatment on the corrosion stability and adhesion of powder polyester coating

One of the most important factors in corrosion prevention by protective coatings is the coating adhesion loss under environmental influence. Thus, adhesion strength is often used when characterizing protective properties of organic coatings on a metal substrate. In order to improve the adhesion of organic coating the metal substrate is often pretreated in some way. In this work, the adhesion of polyester coatings on differently pretreated aluminium surface (by anodizing, with and without sealing, by phosphating and by silane film deposition) was examined. The dry and wet adhesion of polyester coatings were measured by a direct pull-off standardized procedure, as well as indirectly by NMP test. It was shown that under dry test conditions all polyester coatings showed very good adhesion, but that aluminium surface pretreated by silane film showed superior adhesion. The overall increase of wet adhesion for polyester coating on aluminium pretreated by silane film was maintained throughout the whole investigated time period. The different trends in the change of adhesion of polyester coatings were observed for different aluminium pretreatments during exposure to the corrosive agent (3% NaCl solution). The highest adhesion reduction was obtained for polyester coating on aluminium pretreated with phosphate coating. The corrosion stability of polyester coated aluminium was investigated by electrochemical impedance spectroscopy in 3% NaCl solution. The results confirmed good protective properties of polyester coating on aluminium pretreated with silane film, i.e. greater values of pore resistance and smaller values of coating capacitance were obtained in respect to other protective systems, whereas charge-transfer resistance and double-layer capacitance were not measurable during 2 months of exposure to a corrosive agent.     

水性聚苯胺防腐涂料研究

将聚苯胺水性微乳液和环氧树脂共混作为底漆、与环氧树脂面漆复合制成防腐涂料，采用开路电位法评价复合涂层的防腐性能。结果表明，合成聚苯胺水性微乳液所使用的酸介质、聚苯胺乳液的用量和腐蚀介质等对涂层的防腐性能均有影响。以十二烷基苯磺酸(DBSA)为酸性介质合成的聚苯胺水性微乳液，当其用量为50％时，复合涂料的防腐性能最佳，与裸露钢板相比，该复合涂层的平衡开路电位可提高245mV左右。该复合涂料不使用任何有机溶剂，是一种环境友好型绿色涂料。     

Performance of corrosion protective epoxy blend-based nanocomposite coatings: a review

ABSTRACT

Epoxy is a thermosetting polymer with exceptional mechanical robustness, thermal stability, and chemical resistance. This article is devoted to updating development, processing, and physicochemical characterizations of epoxy-based anti-corrosion coatings. Incorporation of different polymers in epoxy matrix has motivated extensive research progress in the field of corrosion protection. Epoxy has been blended with polyaniline, polypyrrole, polythiophene, polyamide, polyester, polyurethane, poly(vinyl alcohol), and polydimethylsiloxane to form corrosion protective coatings. The addition of conducting polymer and nanofiller to epoxy matrix modified the nanocomposite morphology and facilitated the development of passive layer at metal/polymer interface. Consequently, nanocomposite coatings act as physical barrier to hinder the penetration of corrosive ions. Likewise, fine dispersion of nanocarbon and inorganic nanoparticles in compatible blends of epoxy/polyamide, epoxy/polyester, epoxy/polyurethane, and epoxy/poly(vinyl alcohol) has resulted in improved adhesion, wear, barrier and anticorrosion properties of the nanocomposite coatings. Design of epoxy blend-based nano-architectures may facilitate appropriate tailoring of overall performance of the resulting anti-corrosion coatings for advance technical applications including aerospace, automotive, construction, electronic devices, and biomedical relevances. New processing techniques may overcome challenges toward high performance future epoxy-based coatings.     

Corrosion resistance of Pb–Sn composite coatings reinforced by carbon nanotubes

Carbon nanotubes/Pb–Sn composite coatings were prepared by electrodeposition technology. The polarization curves and electrochemical impedance of the Pb–Sn coatings and carbon nanotube/Pb–Sn composite coatings were studied in 3.0 wt% HCl, 10 wt% NaOH, and 3.5 wt% NaCl electrolyte solutions, respectively. The results show that the corrosion potential of carbon nanotubes/Pb–Sn composite coatings were improved in the three kinds of corrosive medium, especially in 3.5 wt% NaCl electrolyte solution, where it increased significantly from −0.592 V (vs SCE) to −0.535 V (vs SCE). In addition, composite coatings have higher electrochemical impedance. Carbon nanotubes can improve the corrosion resistance of lead–tin electroplated coatings.     

WJ--7A3水质稳定剂的性能研究

在对多种水质稳定剂的缓蚀、阻垢效应的研究基础上,研制了WJ-7A3复合配方,并对其各种性能进行比较.结果表明:WJ-7A3水质稳定剂是多功能药剂,缓蚀功能强,阻垢效果好,含磷量低,并兼杀菌灭藻,尤其适用于腐蚀型冷却水系统.     

Hybrid coating on steel: ZnNi electrodeposition and surface modification with organothiols and diazonium salts

Sacrificial electrodeposited ZnNi is currently studied for replacing chromate conversion coatings (CCC) in anticorrosion applications. The present-day performances of ZnNi are still away from those of CCCs and the additional organic layers such as polymers and paints are still permeable and cannot prevent the corrosive species to reach the metal. Suitable adhesion primers could improve the situation by minimizing the access of the corrosive species to the polymer/metal interface.As a contribution to this interface problem, the present work provides a comparison of the protective properties of two structurally related molecules (4-nitrothiophenol and 4-nitrobenzenediazonium) grafted on a ZnNi coating electrodeposited on steel. Films of 4-nitrophenyl have been prepared according to the self-assembly process while films of 4-nitrobenzene have been obtained by electrochemical grafting, n-dodecanethiol being used as model system.The adsorption of these molecules as well as the resulting organic film is characterized by X-ray photoelectron spectroscopy (XPS) and polarization modulation-infrared reflection absorption spectroscopy (PM-IRRAS). The protective properties of the organic films against corrosion are investigated by linear sweep voltammetry (LSV), cyclic voltammetry (CV) and scanning vibrating electrode technique (SVET).     

Studies on corrosion resistant properties of sacrificial primed IPN coating systems in comparison with epoxy–PU systems

The continuous development in the field of protective coatings and the search for newer materials with improved properties have led to the emergence of interpenetrating polymer networks (IPNs) as binders for high performance organic coatings for corrosion protection. In this study, one such ambient curing IPN polymer alloy poly(epoxy–urethane–acrylate) developed specially for use in protective coatings has been studied. Undercoat and a topcoat based on the alloy have been formulated and coated over zinc ethyl silicate primed steel surfaces. Similar formulations based on an epoxy polyamide undercoat and a PU topcoat has been formulated and coated over zinc ethyl silicate primed steel surfaces. Both the systems were evaluated for their physical and corrosion resistant properties by subjecting them to accelerated laboratory tests and field test at a corrosive location. The results are reported and conclusions drawn in this paper.     

Synthesis,characterization and corrosion protection of poly-4-methyl-3-mercapto-1,2,4-triazole/TiO2 composite on copper

The present work deals with the electrochemical synthesis of poly-4-methyl-3-mercapto-1,2,4-triazole (p-MMTA)/TiO₂ composite on metallic copper to evaluate its corrosion protection. The composite was characterized by FT-IR, cyclic voltammetry, X-ray diffraction and energy dispersive X-ray analysis. The distribution of inorganic particles in the polymeric matrix was evidenced from the scanning electron microscopic studies. The corrosion performance of composite coating was evaluated by electrochemical impedance spectroscopy and Tafel polarization measurements in 3.5 % NaCl medium. The p-MMTA/TiO₂ composite showed an excellent corrosion protection ability, which was evidenced from the results of electrochemical measurements. The enhanced ability could be due to the barrier effect of composite coatings against corrosive species and also due to the synergistic effect between organic polymer and inorganic particles.     

Preparation of polyvinylpyrrolidone/graphene oxide/epoxy resin composite coatings and the study on their anticorrosion performance

Waterborne epoxy resin (EP) is often used as anticorrosive coating in the industrial field. However, small holes and gaps can be formed during the curing process. The corrosive medium easily penetrates the anticorrosive coating and corrodes the metal matrix. Herein, polyvinylpyrrolidone (PVP) and graphene oxide (GO) were doped into EP to improve the shielding and resistance to corrosive media. The composite coatings were prepared successfully by solution blending method. In the PVP/GO composite materials, original spatial structure of GO was changed and the composite was mainly combined by covalent bonding. The surface morphology of hybrid filler was flat and uniform, and the structural defects of GO was reduced. Compared with single-layer anticorrosive coating, the corrosion potential of PVP/GO/EP coating moved forward and the corrosion current density decreased. The ideal corrosion resistance of PVP/GO/EP composite coatings was mainly because agglomeration of GO sheet was obviously avoided after it was modified by PVP. Furthermore, the hybrid filler can be uniformly dispersed in the aqueous EP. It blocked the gaps and holes inside the coatings, which could contribute to form anticorrosive coatings.     

Polymeric Corrosion Inhibitors for Iron and Its Alloys: A Review

Several works have been reported on the corrosion inhibition of different metals in various corrosive environments. Initially attention was centered on organic compounds but later focused on green inhibitors. Green inhibitors include nontoxic, eco-friendly polymers and natural inhibitors. In recent years, there has been increased emphasis on applications of polymers, copolymers, grafted polymers, and polymer composites as green corrosion inhibitors. The prime controlling factors influencing the corrosion inhibitive performance of polymeric compounds on the corrosion of metals in various corrosive environments are discussed in this review. The superior performance of a polymeric corrosion inhibitor is due to its larger size and greater number of functional anchoring groups. Through the anchoring groups the polymers easily get adsorbed on the metal surface and cover considerably more surface than the corresponding monomers. The main factors influencing the corrosion mitigating properties of the polymers are molecular size, weight, composition, and nature of the anchoring groups. The solution pH, concentration, exposure time, and temperature also find their role in inhibition performance. In this review, we have tried to cover various types of polymeric corrosion inhibitors for iron and its alloys.     

Corrosion-protective performance of nano polyaniline/ferrite dispersed alkyd coatings

The application of nanotechnology in the corrosion protection of metals has recently gained momentum. A polymer nanocomposite coating can effectively combine the benefits of organic polymers, such as elasticity and water resistance, to that of advanced inorganic materials, such as hardness and permeability. Environmental impact can also be improved by utilizing nanostructure particulates in coatings and eliminating the requirement of toxic solvents. Nanocomposites have also proven to be an effective alternative to phosphate-chromate pretreatment of metallic substrate, which is hazardous due to the presence of toxic hexavalent chromium. This article reports some of the preliminary investigations on the corrosion-resistance performance of soya oil alkyd, containing polyaniline/ferrite nanocomposite. The corrosion-protective performance was evaluated in terms of physico-mechanical properties, corrosion rate, and SEM studies. The polyaniline/ferrite nanocomposite coatings were found to show a far superior corrosion-resistance performance compared to that of a pure PANI/alkyd system.     

高性能氯醚重防腐涂料的研制

通过对氯醚树脂合理的配方设计和配套设计,研制出一种高性能氯醚重防腐涂料,可广泛用于腐蚀严重的化工大气环境。该涂料的综合性能远远高于国内目前氯化橡胶防腐涂料、高氯化聚乙烯防腐涂料,是氯化聚烯烃防腐涂料理想的替代品。     

纳米二氧化硅-有机硅复合涂层防护性能的研究

利用电化学阻抗谱(EIS)技术对纳米二氧化硅含量为5%的有机硅复合涂层的防护性能进行了研究,试验结果与有机硅清漆涂层和微米二氧化硅含量为5%的有机硅复合涂层的实验结果进行了比较。结果表明,纳米氧化硅粒子的填加有效的阻挡侵蚀介质的渗透和腐蚀,纳米氧化硅-有机硅复合涂层比有机硅清漆涂层和微米二氧化硅-有机硅复合涂层具有更好的防护性能。     

环氧/叔胺/丙烯酸树脂三元配比对复合水性涂料性能影响的研究

在掌握环氧树脂与丙烯酸树脂酯化反应凝胶规律的基础上，在临界凝胶方程给出的环氧／叔胺／丙烯酸树脂三角图的非凝胶区域，利用酯化反应合成了不同三元配比的六种环氧丙烯酸树脂复合物，通过研究这六种复合物的相对分子质量、加水乳化和涂膜性能等变化规律，最终给出适合做防腐涂料的配方选择范围和涂料配方设计的指导原则。