Anticorrosion Properties Of Coatings Research Articles

The diffusion and adhesion relationship between free films and epoxy coated mild steel

In order to investigate the effect of adhesion on ionic resistance of coatings, non-pigmented epoxy/polyamide free film and applied coating were compared. The results obtained from electrochemical impedance spectroscopy (EIS) after various immersion times in 3.5 wt% sodium chloride solution showed that the corrosion resistance of the free film attached to the steel surface was by approximately one order of magnitude less than the applied one, indicating the important role of adhesion on the anti-corrosion properties of coatings. For the applied coating, the first signs of corrosion products appeared after 20 days of immersion, while this time was reduced to merely 2 days for the attached free film. Coating capacitance data pointed out that saturation with water for the attached free film was faster and also the amount of absorbed water was higher than the applied coating. Gravimetric water uptake of epoxy/polyamide free film was also determined and compared via EIS data. In addition, epoxy/polyamide free films were placed as membranes against NaCl and KCl solutions with different concentrations. The concentration of alkaline ions in the solution was measured using the flame photometry technique. Among epoxy membranes, the degradation of the sample which faced 3.5 wt% NaCl was more remarkable comparing EIS and FT-IR analysis.

Modification of graphene and its effect on anticorrosive properties of coatings

In this paper, zinc particles were grafted on the surface of graphene by KH550. It was proved that zinc powder was successfully connected to the surface of graphene by KH550 through IR, SEM, energy spectrum and thermogravimetric analysis. The modified graphene is added to the anti-corrosion coating, which effectively improves the anti-corrosion performance of the coating.

Investigation of anti-corrosion property of hybrid coatings fabricated by combining PEC with MAO on pure magnesium

• Novel hybrid coatings are prepared by combining PEC with MAO on pure magnesium. • PEC modified layers play a positive effect on improving corrosion resistance of PEC+MAO hybrid coatings. • PEC+MAO hybrid coatings can further enhance corrosion resistance of pure magnesium. Novel hybrid coatings on pure magnesium were prepared by combining plasma electrolytic carburizing (PEC) with micro-arc oxidation (MAO) to further enhance the anti-corrosion property in this paper. Scanning electron microscopy (SEM) was used to observe the micro-structure of the coatings, meanwhile, energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) were separately used to investigate the elemental as well as phase compositions of the coatings. The anti-corrosion property of the coatings was evaluated by potentiodynamic polarization curves as well as electrochemical impedance spectroscopy (EIS).The results show that PEC process is closely related with the effects of adsorption as well as diffusion of the activated carbon atoms, and it can provide a favorable pretreatment surface with predesigned chemical composition to obtain a new kind of phase, namely SiC with superior corrosion resistance and chemical stability, in the following PEC+MAO hybrid coatings. Meanwhile, PEC preprocessing also can afford an excellent micro-structure to increase the coating thickness as well as to improve the compactness of the PEC+MAO hybrid coatings. During the fabrication process of the PEC+MAO hybrid coatings, an overlapping phenomenon in regard to coating thickness can be observed instead of heaping up layer by layer. Compared with both single PEC surface modification layers as well as single MAO coatings, the PEC+MAO hybrid coatings exhibit more superior anti-corrosion property. Especially, the EIS data reveal that the PEC+MAO hybrid coatings can act as an effective protection system to provide relatively excellent long-range anti-corrosion protection. Note also that employing same MAO technique for both single MAO treatment as well as PEC+MAO combining procedure is the key to this research.

Electrochemical Corrosion Behaviour of Nickel and Nickel-Reduced Graphene Oxide Coatings on Mild Steel in 3.5% NaCl Solution

Nickel-based electrodeposits are extensively used to protect mild steel. The graphene-based materials as corrosion resistive coatings for metallic substrates have been attracted researchers due to their ability to prevent the metal surface. Herein, nickel and nickel reduced graphene oxide (Ni-rGO) composite coatings have been electrodeposited on mild steel using sulphate bath solution. The morphological results reveal that the Ni-rGO coatings exhibited a smaller grain size with less surface defects. It was observed from the scanning electron micrographs images that composite coatings are porous free. The anti-corrosion properties of coatings were further examined by salt spray test. The electrochemical polarization and impedance measurements revealed that Ni-rGO coating enhances the corrosion resistance of mild steel. Electrochemical measurements revealed that the insertion of a few-layered rGO to the Ni matrix increases the corrosion resistance properties of the Ni-rGO coatings.

Fabrication of graphene-coated poly(glycidyl methacrylate) microspheres by electrostatic interaction and their application in epoxy anticorrosion coatings

The uneven dispersion of graphene in the resin matrix hinders its application in anticorrosion coatings. This study reports a new method where graphene oxide (GO) is coated on the surface of the poly(glycidyl methacrylate) (PGMA) microspheres to promote the dispersion of GO in epoxy resin (EP) to improve the anticorrosion performance of EP. GO-coated PGMA microspheres (PGMA@GO) were successfully fabricated by electrostatic interaction, which was confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and zeta potential analysis. The scanning electron microscopy results showed that the PGMA microspheres were uniformly coated with GO, when the weight ratio of PGMA@GO was 1:2 (PGMA: GO). Electrochemical impedance spectroscopy and salt immersion experiments were performed to evaluate the corrosion resistance of the EP composite coatings. Comparing with pure EP and GO/EP coatings, the mechanical properties and anticorrosion properties of coatings were improved after adding PGMA@GO. When the addition amount of PGMA@GO (of 50 g EP) was 1.0 wt% and about 0.67 wt% GO was only needed, the PGMA@GO/EP composite coating possessed a high impedance of 5.68 × 108 Ω cm2 and a low breakpoint frequency of 0.39 Hz for 21-day immersion in 3.5 wt% NaCl solution. The anticorrosion mechanism of PGMA@GO/EP composite coating was also discussed.

Повышение антикоррозионных свойств покрытий на основе цинкового сплава ЦАМСв4-1-2,5 легированием стронцием

Повышение антикоррозионных свойств покрытий на основе цинкового сплава ЦАМСв4-1-2,5 легированием стронцием

REMOVED: The diffusion and adhesion relationship between free films and epoxy coated mild steel

Abstract In order to investigate the effect of adhesion on ionic resistance of coatings, non-pigmented epoxy/polyamide free film and applied coating were compared. The results obtained from electrochemical impedance spectroscopy (EIS) after various immersion times in 3.5 wt.% sodium chloride solution showed that the corrosion resistance of the free film attached to the steel surface was by approximately one order of magnitude less than the applied one, indicating the important role of adhesion on the anti-corrosion properties of coatings. For the applied coating, the first signs of corrosion products appeared after 20 days of immersion, while this time was reduced to merely 2 days for the attached free film. Coating capacitance data pointed out that saturation with water for the attached free film was faster and also the amount of absorbed water was higher than the applied coating. Gravimetric water uptake of epoxy/polyamide free film was also determined and compared via EIS data. In addition, epoxy/polyamide free films were placed as membranes against NaCl and KCl solutions with different concentrations. The concentration of alkaline ions in the solution was measured using the flame photometry technique. Among epoxy membranes, the degradation of the sample which faced 3.5 wt.% NaCl was more remarkable comparing EIS and FT-IR analysis.

Mechanical Properties and Corrosion Resistance of Hard β-W based CVD Coatings in Aqueous NaCl Solution

The paper presents the results of studying the mechanical and anticorrosive properties of coatings based on the metastable tungsten phase (β-W) obtained by means of low-temperature chemical vapor deposition from fluorine-containing media. Corrosion studies in a 5% aqueous solution of NaCl showed that the general corrosion rate of W-based coatings reaches the value of 60 μm/year. The positive correlation between the corrosion rate of coatings and their hardness indicates a significant effect of the stressed state of the coatings on their corrosion behavior.

Study on the properties of a novel electrostatic conductive and anti-corrosive composite coating improved by graphene nanosheets

As for oil containing facilities, the problem of electric charge accumulation is harmful, and effective measures should be taken to solve it. Coatings are widely used as a common technology for anti-corrosion and electrostatic conduction. In this paper, Antimony Tin Oxide powder (ATO) and graphene (G) nanosheets were introduced to prepare a novel electrostatic conductive and anti-corrosive composite epoxy coating for the protection of oil deposit tanks and oil transfer pipelines. The feature of ATO and G nanosheets dispersed in the coating was characterized by scanning electron microscopy. At the same time, the electrical conductivity and anti-corrosion properties of coatings were studied by surface resistivity tester and electrochemical impedance spectroscopy (EIS). The results showed that the surface resistivity of the composite coating was improved 10 times by introducing an appropriate amount of graphene and ATO, and exhibited excellent corrosion resistance, high impedance modulus during 144 days of soaking, while epoxy coating failure after 87 days of soaking. The differential effects of ATO and G were compared and discussed.

Anti-corrosion and wear resistance properties of polymer composite coatings: Effect of oily functional fillers

Abstract We herein report the development of carbon-modified porous fillers that function as micro-reservoirs to store lubricating oil as a low-friction and anticorrosive agent in a composite coating. These novel oily particles were added to an epoxy resin (EP)-based coating to study the effect of a lubricating oil on the anti-corrosion and friction performances of the coating. Analysis by electrochemical impedance spectroscopy and sliding wear tests demonstrated that the presence of particles containing the lubricating oil significantly improved the barrier properties and the wear resistance of the EP coating. It was therefore apparent that the carbon surface modification of the Celatom filler improved the compatibility of both the filler towards the resin. Thus, the addition of fillers containing lubricating oil further improved the wear resistance and anti-corrosion properties of the coatings.

Anti-corrosion properties of coatings with manganese compounds pigmentation

Work investigates properties of corrosion-resistant coatings based on organic-aqueous emulsion and pigmented compounds of manganese, obtained by ceramic method. It is found that the inclusion of synthesized pigments in the composition of the coating increases their ability to inhibit underfilm corrosion of steel.

Anticorrosive and insulating properties of cardanol based anhydride curing agent for epoxy coatings

Present research reveals the synthesis of anhydride curing agent for preparation of anticorrosive epoxy coatings. A novel dianhydride compound was synthesized from cardanol and used as a curing agent for commercial epoxy resin. The structure of the curing agent was confirmed by chemical and spectroscopic analysis. Coatings were formulated with varying ratio of epoxy resin to anhydride on equivalent basis such as 1:0.6, 1:0.8, 1:1. The effect of varying concentration of curing agent on mechanical, chemical, optical, thermal, electrical and anticorrosive properties of coatings was investigated and compared to coatings cured with commercial methyltetrahydrophthalic anhydride (MTHPA). It was observed that, curing agent based on cardanol performed extraordinarily in all aspects as compared to the commercial curing agent.

Synthesis and characterization of thermally curable guaiacol based poly(benzoxazine-urethane) coating for corrosion protection on mild steel

Biobased hydroxyl functional benzoxazine monomer was synthesized from Guaiacol (lignin derivative) by Mannich condensation reaction using solvent less method. The structure of hydroxyl functional benzoxazine monomer was elucidated from FTIR, 1H NMR, 13C NMR spectroscopy and mass spectrometry. The ring opening polymerization conversion with respect to time was estimated by 1H NMR. Thermal curing behaviour of benzoxazine monomer was studied by DSC. The hydroxyl functional benzoxazine monomer was cured with isocyanate hardener in varying concentrations based on equivalent weight to prepared the poly(benzoxazine-urethane) (BZPU) coatings. After thermal curing, BZ and BZPU coatings were examined by FTIR analysis. The effect of varying concentrations of isocyanate hardener with benzoxazine monomer on mechanical, chemical, solvent, thermal and anticorrosive properties of coatings was investigated. The study revealed that, an increased concentration of urethane moieties in BZPU coatings improved the mechanical, chemical and thermal properties, compared to pure polybenzoxazine (BZ) coating. The effect of urethane content on corrosion resistance of BZPU coatings were investigated by salt spray and electrochemical impedance spectroscopy (EIS) technique. The results shown that corrosion resistance of BZPU coating enhanced with increasing urethane content in polymer backbone. The protection efficiency values for BZPU coatings were found more than 97%.

Influence of cross-linking agents and curing condition on the performance of epoxy coating

Purpose The performance of epoxy coating on metal substrate at low temperature and high humidity application has adverse effect on cure rate, film properties and adhesion. In recent years, several advanced amine cross-linking agents having superior curing ability at low temperature application environment have been introduced. The aim of this paper is to study the properties of epoxy-based coating cured with different cross-linking agents designed for low temperature application at different environmental conditions. Design/methodology/approach Series of cross linking agents such as modified cycloaliphatic amine (H1), polyamine adduct (H2), modified aliphatic ketamine (H3), phenalkamine (H4) and phenalkamide (H5) have been studied to evaluate their performance in epoxy compositions when cured at four environmental conditions, i.e. at ambient and sub-ambient temperatures with 60 and 90 per cent relative humidity, respectively. The effect of curing conditions was investigated by evaluating different physico-mechanical properties. Dynamic mechanical analyser technique was used to determine glass transition temperature (Tg) and cross-link density (ρ) of coatings. Anticorrosive properties of coatings also have been studied by electrochemical impedance spectroscopy. Findings The outcome of this study is expected to generate new insight into the curing behaviour of epoxy coating using different cross-linking agents which are recommended for low temperature application. Optimum physico-mechanical and corrosion resistance properties have been obtained by phenalkamine curing agent at low temperature and high humidity condition. Practical implications This study is an experimental approach to select the better cross-linking agent for low temperature application. Different test conditions were measured for understanding the performance of epoxy coating cured at different environmental condition. Originality/value The understanding reaction mechanism of the epoxy resin with cross-linking agent at different environmental condition is the great challenge and is hardly investigated in the literature. Therefore, in this research, the influence of climatic conditions and type of cross-linking agents on curing behaviour of epoxy-based coating was investigated.

Formation of bioactive anticorrosion coatings on resorbable implants by plasma electrolytic oxidation

Calcium phosphate coatings (Ca/P = 1.61) containing magnesium oxide MgO and hydroxyapatite Ca10(PO4)6(OH)2 accelerating the growth of bone tissue have been prepared by the method of plasma electrolytic oxidation (PEO) on MA8 magnesium alloy. The phase and element compositions, morphology, and anticorrosion properties of coatings were investigated. Such PEO layers were found to essentially reduce the corrosion rate of magnesium alloy (polarization resistance being increased by two orders). This makes it possible to consider the formed PEO coatings as likely anticorrosion layers for medical bioresorbable implants.

Effect of current density on the structure, composition and corrosion resistance of plasma electrolytic oxidation coatings on Mg–Li alloy

The effect of current density on the oxidation process, morphology, composition and anti-corrosion properties of coatings are elucidated. X-ray photoelectron spectroscopy and X-ray diffraction analysis of coatings show that coatings prepared at different current densities are composed of MgO and γ-Mg2SiO4 and α-Mg2SiO4 phase. The chemical composition of PEO coatings varies from surface to the interior of the oxide coating. The PEO coatings exhibit tunable thickness, composition ratio, and porosity by controlling the current density, which ultimately affects film morphology and anti-corrosion properties. The superior corrosion resistance of coating obtained at 5A/dm2 is attributed to the compactness of the barrier layer and the highest MgO/Mg2SiO4 ratio.

Characterization and Electrochemical Investigations of Polypyrrole/Aluminum Flake Composite Pigments on AA 2024-T3 Substrate

Phosphate and nitrate doped Polypyrrole (PPy)/Aluminum (Al) flake pigments were synthesized by chemical oxidative polymerization method. Coatings were formulated from the phosphate doped PPy/Al flake pigment, nitrate doped PPy/Al flake, and as received Al flakes at 20% pigment volume concentration (PVC). The anticorrosion properties of coatings on aluminum alloy (AA 2024-T3) were monitored by exposure with accelerated salt spray (ASTM B117), electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET), and anodic polarization experiments. Phosphate and nitrate doped PPy/Al flake coatings showed enhanced anticorrosion ability in comparison with as received Al flake coating as observed in accelerated salt spray test. In the anodic polarization experiments, phosphate and nitrate doped PPy/Al flake coatings exhibited a positive shift in the potential suggesting the passivation of the substrate. Additionally, SVET experiments did not detect appreciable corrosion activity for the samples demonstrating better corrosion protection ability of phosphate and nitrate doped PPy/Al flake coatings.

Performance Evaluation of SHY-99 Coating for Carbon Steel Water-Cooler

Special SHY-99 anti-corrosion coatings are used for newly developed heat exchange equipment, to resist corrosion and leakage problem of carbon steel water-cooler. The anti-corrosion properties of coatings were examined with routine test methods, Scanning Electron Microscope (SEM), electro kinetic potential polarization curve method and immersion testing method. The results show that physical properties of coatings are in accordance with national standards, the microstructures of coatings are uniform and tight, the coatings are combined tightly with base metal, and the coatings show excellent corrosion resistance in water of water cooling system.

The influence of ultra-fine glass fibers on the mechanical and anticorrosion properties of epoxy coatings

The effects of different contents of ultra-fine glass fiber on mechanical and anticorrosion properties of epoxy coatings have been investigated. The FTIR and SEM have been used to analyze the surface nature and microstructure of the coatings. Electrochemical impedance spectroscopy (EIS) and a salt spray test have also been used to characterize the contents of ultra-fine glass fibers on the impedance of the coatings. When 10%, 20%, 30% of ultra-fine glass fibers are added to the coatings, their hardness and adhesion increases by 67%, 67%, 200% and 21.6%, 39%, 40%, respectively, compared with the properties of the pure coating. But the anticorrosion properties of the coatings containing high ultra-fine glass fiber content decreased with respect to the pure coatings properties.

Comparison of the coatings deposited using Ti and B4C powder by reactive plasma spraying in air and low pressure

The coatings were deposited by reactive plasma spraying (RPS) in air and low-pressure plasma spraying (LPPS) based on the reaction between Ti and B4C powder, respectively. The thermal spray powder of Ti and B4C added with powder Cr (metallic binder) in air is compared with that without powder Cr addition in the low pressure. (Prior to deposition, the powder was screened and separated for RPS whereas spray drying, sintering and sieving were done for LPPS.) The phase composition and the microstructure of coatings were studied by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The anti-corrosion property of coatings was also investigated. It is found that the coating prepared by RPS, which is more densification, is composed of TiN, TiB2, and a small phase fraction of titanium oxides. The composition of the coating deposited by reactive LPPS is TiB2, Ti(C, N), Ti4N3−x and impurity phase of Ti5Si3. There is no appearance of titanium oxides in low pressure. The coatings have the typical lamellar structure and adhere to the bond coating well. The mean Vickers microhardness value of the coating deposited by RPS is higher than that of the coating deposited by LPPS. Furthermore, the corrosion resistance of the coating deposited by RPS is superior to that of the coating prepared by LPPS in near neutral 3.5 wt% NaCl electrolyte.