Corrosion Resistance Of Composite Coatings Research Articles

Effect of chemical bonding between fluorographene and fluororesin on the anti-corrosion properties of their composite coating

Fluorographene has unique advantages in the corrosion protection of heat exchangers. Excessive fluorographene loading can ensure the thermal conductivity performance of coatings, however, it also damages the coating integrity and reduces the corrosion resistance. Therefore, the project focuses on the effects of interfacial compatibility between fluorographene and polymer on the corrosion resistance of composite coatings. Fluorographene and fluororesin have been modified to prepare composite coatings (K-PFA). This modification improves the dispersion of fluorographene in the coating matrix and enhances the interface compatibility between the two materials. The crystallinity of the composite coating has increased from 33.66 % to 40.25 %. The corrosion protection performances of K-PFA are improved due to the reduction in water vapor and oxygen permeability by 83.8 % and 73.1 %, respectively, and the coating resistance of K-PFA is 3–4 times higher than that of blank coating. By utilizing surface modification techniques, the interface compatibility between fluorographene and the coating has been optimized, resulting in enhanced anti-corrosion properties for coatings.

Nonconductive layered hexagonal boron nitride preparation via a co-exfoliation strategy and nanohybrid coating construction for corrosion protection

Hexagonal boron nitride (h-BN), an analogue of graphene with similar layered structure, is considered as the promising material in place of graphene for application as nanofiller into polymeric matrices to develop the smart coatings for corrosion protection of metallic substrates, owing to its mechanical robustness and thermal stability together with unique electrically insulating nature. In this work, on the basis of a co-exfoliation strategy, h-BN were exfoliated by riboflavin sodium phosphate (FMN) intercalator, assisted with ball-milling to obtain few-layered nanosheets with improved water-dispersibility as well as improve their compatibility with waterborne epoxy matrix. The results from electrochemical measurement and corrosion product analysis indicate that the incorporation of only 1.0 wt% FMN-exfoliated h-BN (h-BN@FMN nanohybrids) content into waterborne epoxy matrix can realize the optimized long-term corrosion resistance of composite coatings in 3.5 wt% NaCl solution. The two-dimensional morphology and impenetrability of h-BN, together with the compatibility of waterborne epoxy system from the bridge role of FMN molecules to act as a physical barrier against corrosive species (i.e., H2O, Cl− and O2), are the main reasons behind the prominent anticorrosion performance of our composite coating.

Active and passive corrosion protection coating based on NaY zeolite

The coating of a surface with organic material is the simplest and most effective method to prevent metal materials from corrosion. However, pure resin coatings are prone to corrosion, as corrodents can penetrate the metal surface via micropores. Moreover, passive corrosion resistance, achieved by adding a filler to a coating to lengthen the penetration path of the corrodent, is not sufficient to prevent corrosion. Therefore, the development of coatings with active and passive corrosion resistance properties is necessary to extend the lifetime and enhance the performance of coatings. Herein, a coating with active and passive corrosion resistance properties was designed by loading a NaY zeolite nanocarrier with the corrosion inhibitor benzotriazole (BTA), with a NaY zeolite nanocarrier loading capacity of 7.22 %. The release properties of the resulting NaY@BTA and the corrosion inhibition of BTA released under different pH conditions were investigated. The adhesion strength, contact angles (CAs), and water absorption of the composite coatings were evaluated. The coating with 0.5 % nanocarrier exhibited an adhesion strength of 4.68 MPa, a CA of 84.78°, and the lowest absorbed water content of 1.28 %. The corrosion resistance of composite coatings with different amounts of NaY@BTA was compared, with the electrochemical impedance spectroscopy data of intact and scratched coatings displaying their excellent active corrosion resistance and self-repair properties. After immersion in 3.5 % NaCl solution for 60 days, the low frequency Z0.01 Hz value of EP–PU-0.5%NaY@BTA was 1011 Ω.

Revealing the Impact of Micro-SiO2 Filer Content on the Anti-Corrosion Performance of Water-Borne Epoxy Resin.

Due to green development in recent years, water-borne epoxy resins (WBE) have become increasingly popular since they generate the lowest level of volatile organic compounds (VOC) during curing. However, because of the large surface tension of water, it is easy to produce voids and cracks during the curing process of the coating. An electrochemical strategy was used in this study to assess the impact of different SiO2 content on the corrosion performance of a WBE coating, in which micron spherical SiO2 particles were synthesized in a liquid phase reduction. The results showed that the synthesized micron spherical SiO2 particles were about 800 ± 50 nm in diameter and in an amorphous state. By hydrophilizing the surfaces of these SiO2 particles, uniform dispersion in an aqueous solvent and a WBE can be achieved. It is important to note that adding a small or excessive amount of SiO2 to a coating will not improve corrosion resistance and may even reduce corrosion resistance. With the appropriate modification of SiO2, corrosion resistance of composite coatings is greatly enhanced, as is the adhesion between the coatings and the metallic substrates. Because the appropriately modified SiO2 can effectively fill the pores that are formed during the curing process, a corrosive medium is less likely to react with the matrix when the medium comes into contact with the matrix. Based on their incorporation content of 3 wt.%, their corrosion resistance is the best after 16 cycles of AC-DC-AC accelerated corrosion tests.

Enhanced corrosion resistance of layered double hydroxides/steam coating composite coating prepared by the hydrothermal method on LA43M magnesium–lithium alloy substrates

AbstractAn excellent anticorrosion Mg–Al layered double hydroxide (LDH) composite coating was successfully fabricated on LA43M magnesium alloy substrates via an in situ steam coating (SC) process and a subsequent hydrothermal treatment at different temperatures. The microstructure, composition and phase formation of the composite coatings were studied via X‐ray diffractometer, energy disperse spectroscopy, and scanning electron microscope, respectively. The corrosion resistance of composite coatings was further investigated using electrochemical measurements and corrosion test. The results showed that LDH/SC composite coating has typical nanosheets microstructure, which effectively seal the defects of SC. As the hydrothermal temperature increases, the thickness and density of nanosheets increases, and the corrosion resistance was significantly improved. Especially, the Mg–Al LDH/SC composite coating prepared at 100°C was the most dense and thickness, and exhibited the optimal and long‐term anticorrosion resistance in 3.5 wt.% NaCl soultion. It has the lowest Icorr (1.767 × 10−8 A/cm2), which decreased by three and two orders of magnitude compared with the bare substrate and SC. Furthermore, it can maintain good chemical stability after immersion in the corrosion medium for 192 h and its hydrogen evolution rate (0.00416 mL·cm−2·h−1) and weight lost rate (0.00266 mg·cm−2·h−1) were the lowest compared with other samples.

Effect of boron carbide reinforcement on surface properties of electroless Ni–B and Ni–B–W coatings

Today, composite coating of nickel-boron with an electroless method is considered as an innovative, attractive, and trend topic. It is known that the hardness and tribological properties of electroless nickel-boron (EN-B) coating can be improved with co-deposition of ceramic particles. In this study, boron carbide (B4C) was added to binary (Ni–B) and ternary (Ni–B–W) EN-B coatings: (i) Ni–B–B4C, and (ii) Ni–B–W–B4C. Surface morphology, phase structure, tribological characteristics, and electrochemical behaviors for all coatings were investigated and compared. The surface morphology of composite coatings was transformed from cauliflower to cloudy-shaped with the addition of B4C particles. Characteristic amorphous structure with some degree of crystallinity was obtained at all types of coatings. Experimental test results revealed that the boron carbide particles provide a noticeable enhancement in hardness. The hardnesses of composite coatings were improved by approximately 52% in Ni–B–B4C and 62% in Ni–B–W–B4C compared to EN-B coatings. Boron carbide reinforcement and poly-alloying with tungsten caused an increase of hardness at Ni–B from 673 HV0.025 up to around 1096 HV0.025 (Ni–B–W–B4C) which is a noticeable increase in hardness. With boron carbide addition binary and ternary coatings wear factors showed a discernible diminishment by several times. Besides, electrochemical analyses indicated a minimal decrease in the corrosion resistance of composite coatings compared to that of Ni–B and Ni–B–W coatings.

Study on Corrosion Resistance of LDH/Micro-Arc Oxidation Composite Superhydrophobic Coatings on AZ31 Magnesium Alloy

Because of some defects such as holes and cracks, the corrosion resistance of micro-arc oxidation coating needs to be improved by surface modification. In this paper, LDH/MAO film with a micro-/nano-structure is constructed on the surface of AZ31 magnesium alloy by controlling the composition and concentration of the hydrothermal solution. The superhydrophobic surface is successfully constructed by coating an OTES modifier on the surface of LDH/MAO film by the spin-coating method. The surface morphologies, contact angles, and corrosion resistance of composite coatings are tested. The results show that the OTES-LDH/MAO composite coatings of magnesium alloy can seal the defects in the MAO film well to achieve a superhydrophobic effect and better corrosion resistance. Compared with a MgO ceramic film, the water contact angle of OTES-LDH/MAO composite coatings is increased from 38° to 155°; the corrosion potential increases by 0.7 V, the corrosion current density and polarization resistance decreases and increases by four orders of magnitude, respectively; and the corrosion resistance becomes much higher than that of MAO film.

Pulse Electrodeposited Super-Hydrophobic Ni-Co/WS2 Nanocomposite Coatings with Enhanced Corrosion-Resistance

The hydrophobicity and corrosion resistance of composite coatings can be effectively improved by changing the electrodeposition method and adding inorganic nanoparticles. In this work, the incorporation of WS2 nanoparticles significantly increased the surface roughness of Ni-Co coatings. The best hydrophobicity and corrosion resistance of the Ni-Co/WS2 nanocomposite coatings (water contact angle of 144.7°) were obtained in the direct current electrodeposition mode when the current density was 3 A/dm2 and the electrodeposition time was 50 min. Compared with direct current electrodeposition, the pulsed current electrodeposition method was more conducive to improving the electrodeposition performance of the nanocomposite coatings. Under the conditions of a current density of 3 A/dm2, pulse duty cycle of 70%, and pulse frequency of 1000 Hz, the nanocomposite coatings reached a superhydrophobic state (water contact angle of 153.8°). The nanocomposite coatings had a slower corrosion rate and larger impedance modulus in this state, and thus the corrosion resistance was superior. The wetting state of the Ni-Co/WS2 nanocomposite coating surface was closer to the Cassie–Baxter model. The protective air layer formed by the layered rough microstructures significantly reduced the actual contact area between the liquid and the substrate, achieving excellent hydrophobic and corrosion resistance properties.

Preparation and Properties of Pulsed Composite Coatings of Supercritical Graphene Quantum Dots

Using graphene quantum dots with unique properties as the second phase additive and utilizing the high diffusion and transfer properties of supercritical fluids, Ni-based nanocomposite coatings were prepared by pulsed electrodeposition technology. The effects of the pulse duty cycle on the microstructure, mechanical properties, and corrosion resistance of composite coatings were investigated. The results showed that the graphene quantum dots are successfully embedded in the coatings, and under supercritical conditions, a suitable pulse duty cycle can improve the surface density and sphericity of the coatings. Raman spectroscopy and carbon-sulfur analyzer test indicated that supercritical conditions can improve the quality and content of graphene quantum dots in the coatings. The graphene quantum dots composite coating prepared when the pulse duty cycle is 0.3 has more excellent mechanical properties. Its microhardness is higher, and it has a smaller friction coefficient and wear scar cross-sectional area. Tafel polarization experiments indicated that under supercritical conditions, the corrosion current density of graphene quantum dots composite coating prepared when the pulse duty cycle is 0.3 is small, which is 1.286 × 10−5 A·cm−2. The 120 h immersion corrosion study showed that no obvious corrosion occurs on the surface. Therefore, its corrosion resistance is more excellent.

Influence of aluminum on structural-phase state, corrosion resistance and tribomechanical properties of composite coatings obtained by hypersonic metallization

The structural-phase state, tribotechnical and durometric properties of hypersonic coatings made of steels 95Cr18 and 06Cr19N9T, as well as pseudo-alloys 95Cr18—AD1 and 06Cr19Ni9Ti—AD1, obtained by hypersonic metallization, have been investigated. It was found that the sprayed coatings from pseudo-alloys 95Cr18—AD1" and 06Cr19Ni9Ti—AD1 contain mainly α-Fe, which is due to alloying of steel particles in the process of spraying with aluminum. It is shown that coatings made of 95Cr18 and 06Cr19Ni9Ti steels have a higher wear resistance under dry friction conditions as compared to composite coatings. The reduced wear resistance of pseudo-alloys is associated with the presence of a large amount of relatively soft aluminum in them. It is shown that the corrosion resistance of a composite coating made of Fe—Al in a 10 % aqueous solution of NaCl is about 2 times higher than that of coatings made of high-chromium steels 95Cr18 and 06Cr19Ni9Тi.

Corrosion Resistance of Composite Coatings Based on the Alloys of Cobalt With Refractory Metals

Corrosion Resistance of Composite Coatings Based on the Alloys of Cobalt With Refractory Metals

Enhancing the barrier effect of sol-gel derived inorganic coating by doping h-BN nanosheet

Nanocomposites filled with impermeable two-dimensional materials are of specific interest for protecting metal from corrosion. The addition of hexagonal boron nitride nanosheet (BNNS) into a coating matrix can improve the barrier effect virtually due to its high chemical and thermal stability and dielectric property. This atom-level thick filler involves a «tortured pathway» that prolongs the penetration distance to the substrate. In this study, BNNS was added into a zirconium coating prepared via sol-gel way. In order to understand the influence of nanosheets size on the barrier performance, three h-BN grades were used. It was intended to keep all the other elaboration parameters constant so that the electrochemical behavior variation is mainly attributed to the nanosheet size. The morphology and microstructure of hexagonal boron nitride flakes in different exfoliation level and the nanocomposite coating were studied by SEM, HRTEM, SAED, FTIR cartography, Raman spectroscopy. Meanwhile, the corrosion resistance of composite coatings was characterized by polarization test and long-term electrochemical impedance spectroscopy in a 3.5 wt% NaCl solution.

Effect of the feeding mode of cross-linker and microcapsule on the corrosion resistance and hydrophobicity of composite coatings

The interface combination of anti-corrosive materials and polymer matrix has a significant effect on the overall performance of the composite coating. However, past research has focused on blending anti-corrosive materials to improve the performance of the polymer matrix. Herein, we proposed a layer-by-layer spray-coating process to further enhance the reinforcing effect of anti-corrosive materials on the polymer matrix by changing their feeding modes. In this paper, taking waterborne polyacrylate (WPA) as an example, two kinds of reinforcement materials commonly used to improve the corrosion resistance of polymer matrix were introduced into the coating system and then applied to the tinplate: cross-linker and microcapsule. Firstly, five types of WPA composite coating systems were designed according to the feeding mode of aziridine cross-linker and the position of benzotriazole@zinc oxide microcapsules (BTA@ZnO MCs). Electrochemical impedance spectroscopy (EIS) and electrical equivalent circuits were used to evaluate the corrosion resistance of these composite coating systems and analyze their electrochemical processes. By spraying the mixture of WPA and aziridine crosslinker as the bottom layer and BTA@ZnO MCs as the top layer, the resulting composite coating exhibited higher corrosion resistance and hydrophobic properties. Scanning electron microscope (SEM) and contact angle tests indicated that the feeding mode of aziridine cross-linker and the position of BTA@ZnO MCs played important roles in the compactness and hydrophobicity of the composite coating. Subsequently, the effects of the amount of aziridine cross-linker and BTA@ZnO MCs on the corrosion resistance and physical properties of the composite coating were further analyzed by EIS, water absorption test, contact angle test and atomic force microscopy (AFM). The significant improvement in the corrosion resistance of this composite coating was mainly attributed to the synergistic effect of highly cross-linked network structure and superhydrophobic surface.

Effect of Graphene Oxide Decorated With Synthesized Nano-CeO2 on Barrier Properties of Epoxy Anticorrosion Coatings

In this paper, graphene oxide decorated with cerium oxide (CeO2) nanoparticles was prepared and used as anticorrosive pigments in epoxy nanocomposite coatings. The synthesized nanoparticle was characterized by FTIR, XRD, SEM, and EDX analyses. Graphene oxide decorated with CeO2 nanoparticles was dispersed in epoxy resin by sonication. The optimum nanoparticle content of the epoxy resin was studied by differential scanning calorimetry. The anticorrosive properties of these coatings were investigated using electrochemical impedance spectroscopy method and polarization in corrosive solution. Impedance parameters showed a decrease in the coating resistance over immersion time. The results indicated that the epoxy coatings containing nanoparticles could significantly increase the corrosion resistance of composite coatings compared to those of pure epoxy, and the highest value was obtained for 1% nanocomposite coatings after 270 days of immersion. Pull-off adhesion test showed that the highest value of adhesion was related to the coating containing 1% nanoparticles.

In-situ synthesized novel eyeball-like Al2O3/TiC composite ceramics reinforced Fe-based alloy coating produced by laser cladding

In this study, the precursor mixtures of Fe-Cr-C-B alloy powders and 0, 10 and 20 wt% Ti3SiC2 is successfully cladded on 16Mn steel substrate by laser cladding (LC). Microstructure and properties of composite coatings are explored by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectra (XPS), electrochemical workstation, Vickers hardness tester and UMT-2 tribo-meter. Results show that the phases in the composite coating with Ti3SiC2 addition mainly are super saturated solid solution α-Fe, hard phases such as eyeball-like Al2O3/TiC composite ceramics, Ti(B,C)2, TiC, Fe3C, γ-(Fe, Ni)/(Cr, Fe)23C6 laminar eutectics and Ti3SiC2 etc. The microhardness, wear and corrosion resistance of composite coatings increase with the weight percent of Ti3SiC2 increasing from 0 to 20%. The existence of super saturated solid solution α-Fe, hard phases such as Al2O3/TiC composite ceramics, Ti(B,C)2, TiC and Fe3C etc. and the Ti3SiC2 solid lubricant contribute to the higher microhardness and wear resistance. The increased corrosion resistance of coatings is attributed to the fact that Cr is the important element which increases the corrosion resistance of the composite coating. With Ti3SiC2 addition increasing, more Ti atoms are easy to interact with C atoms to form TiC carbides, which remain higher content of free Cr atoms in composite coatings.

Improvement of Corrosion Resistance of Waterborne Polyurethane Coatings by Covalent and Noncovalent Grafted Graphene Oxide Nanosheets.

The amphiphilic graphene derivative was prepared by covalent grafting of graphene oxide (GO) with isophorone diisocyanate and N,N-dimethylethanolamine and then noncovalent grafting of GO with sodium dodecylbenzenesulfonate. The results obtained from infrared spectroscopy, X-ray photoelectron spectroscopy, thermal gravimetric analysis, and X-ray diffraction analysis revealed that the short chains were successfully grafted onto the surface of GO. Subsequently, scanning electron microscopy and optical microscopy results showed that the modified GO (IP-GO) has the best dispersibility and compatibility than GO and reduced GO in the waterborne polyurethane matrix. The relationship between the corrosion resistance of composite coatings and the dispersibility of the graphene derivative and the compatibility of the graphene derivative with a polymer matrix were discussed. The anticorrosive properties were characterized by electrochemical impedance spectroscopy analysis and salt spray tests. Through a series of anticorrosion tests, it is concluded that the anticorrosion performance of a composite coating with 0.3 wt % IP-GO is significantly improved. The excellent anticorrosion performance is due to the perfect dispersion and good compatibility of IP-GO in waterborne polyurethane.

ANNEALING BEHAVIOR OF Ni-TiO2NANOCOMPOSITES

Ni-TiO2nanocomposite have been prepared by electrodeposition. The microstructure and tribological behavior of Ni-TiO2nanocomposite before and after annealing have been investigated compared with as-deposited Ni-TiO2composite. The results demonstrated that TiO2nanoparticles usually collected along the grain boundaries and nickel grains changed from columnar grains into equiaxed grains after annealing. HRTEM photographs indicated that the diffusion between crystalline nickel and TiO2nanoparticles did happen after annealing. Wear results indicated that the main wear mechanism of as-deposited Ni-TiO2nanocomposite was adhesion wear. The wear resistance of Ni-TiO2nanocomposite heat-treated is better than as-deposited Ni-TiO2nanocomposite because the oxidation layers on the worn surface of Ni-TiO2nanocomposite masked the strengthening effect of small grain size. The corrosion behavior also has been studied and it is found that annealing reduces the corrosion resistance of composite coatings.

Microstructural Evolution and Corrosion Behavior of ZnNi-Graphene Oxide Composite Coatings

This work correlates microstructural evolution and corrosion behavior of electrodeposited ZnNi-graphene oxide composite coatings. Incorporation of GO improved the coating compactness and decreased the surface roughness. Structural characterization revealed that the pure ZnNi coating contained only intermetallic phases (γ-NiZn3, γ-Ni3Zn22, and γ-Ni5Zn21), whereas ZnNi-GO coatings contained Zn phase along with the intermetallics. Addition of GO gradually increased the volume fraction of the Zn phase and reduced its crystallite size. With the addition of GO, a noticeable and systematic variation in the growth texture of the coatings was also observed. Corrosion resistance of the composite coating increased with increase in the addition of GO. Microstructural characterization revealed that the composite coating contained Zn phase along with the GO forming a Zn-GO matrix containing intermetallics. Further investigation of the GO extracted from the electrolyte bath revealed that during the electrodeposition process, Zn nucleated and grew over the GO in the electrolyte itself which led to the co-existence of Zn and GO in the coating matrix. Enhancement in the coating compactness, increase in the Zn phase which is sacrificial, and the impermeability of the GO led to the high corrosion resistance of the ZnNi-GO composite coatings when compared to the pure ZnNi coating.

Effects of Interfacial Interaction on Corrosion Resistance of Polybenzoxazine/SiO2 Nanocomposite Coatings

The interfacial interaction between the two phases in polybenzoxazine/SiO2 nanocomposite coatings was controlled through modifying surface functionalities of SiO2 nanoparticles (SNP). SNPs with methyl, epoxide, and benzoxazine groups on the surface were prepared in this work, which was characterized by FTIR, TGA, and elemental analysis. The strong chemical bonding between nanoparticles and polybenzoxazine was obtained because of the reaction between epoxide groups or benzoxazine groups and benzoxazine molecular during the curing process. Both surface properties and corrosion resistance of composite coatings were fully investigated with the assistance of SEM, EDS, water contact angle measurement, and EIS technique. SNP incorporation could reduce porosity of the coatings so significant that all SNP loading nanocomposite coatings exhibited excellent corrosion resistance with a charge transfer resistance of over 1 GΩ cm2 during 31 days’ immersion in a 3.5 wt % NaCl aqueous solution, which was 3 orders of magn...

Anti-corrosion mechanism of 2D nanosheet materials in waterborne epoxy coatings

Nowadays, 2D nanosheet materials play a crucial role in enhancing the corrosion resistance ability of organic coatings. In this work, three kinds of 2D nanosheet materials with different conductivity including graphene (G), graphene oxide (GO) and hexagonal boron nitride (H-BN) were specially chosen and functionalized by 3-aminopropyltriethoxysilane (APTES). Then, a series of waterborne epoxy composite coatings were fabricated by incorporation of functionalized graphene (FG), graphene oxide (FGO) and hexagonal boron nitride (FH-BN). The microstructure and morphology feature of FG, FGO and FH-BN were characterized by Fourier transform infrared spectroscopy, x-ray diffraction, scanning electron microscopy and transmission electron microscopy. The corrosion resistance of composite coatings was obtained by Tafel analysis and electrochemical impedance spectroscopy measurements by being immersed in a 3.5 wt% NaCl aqueous solution for different periods. It turns out that the composite coating with FH-BN additive exhibited the best anticorrosive ability among all samples. The analysis of corrosion products on the Q235 surface suggest that the anticorrosive performance of 2D materials reinforced epoxy composites coatings were not only dependent on the barrier properties but also was affected by the properties of the 2D nanosheet materials. In addition, the distinct anti-corrosion mechanisms of 2D nanosheet materials incorporated with waterborne epoxy were tentatively discussed.