A.G. Mohan Das Gandhi, K. Soorya Prakash and V. Kavimani
This paper aims to examine the investigations made on the corrosion behaviour of magnesium (Mg) substrate electrodeposited using different nano-materials.
Abstract
Purpose
This paper aims to examine the investigations made on the corrosion behaviour of magnesium (Mg) substrate electrodeposited using different nano-materials.
Design/methodology/approach
This study uses nano-materials such as those of reduced graphene oxide (r-GO), titanium-di-oxide (TiO2) and also r-GO/TiO2 nano-composites (dispersed through ultra-sonication process) at 3-min time interval. Crystalline nature of synthesized TiO2 is studied through X-ray diffraction and its pore volume is measured to be approximately 0.1851ccg-1 by Brunauer Emmett Teller analysis.
Findings
Surface morphology of the developed set of specimens inspected through scanning electron microscopy and energy dispersive spectroscopy establishes a clean surface coating and further witnesses for only minimal defects. Electrochemical behaviour of the developed coating is studied exhaustively using Tafel polarization and electrochemical impedance spectroscopy in 0.1 M Na2SO4 solution.
Originality/value
Incremental corrosion resistance exhibited by developed composite coating owes to the factors viz. chemical stability and hydrophobic tendency of TiO2 and r-GO; these known engineering facts resist the flow of ions into the corrosive media and thereby reduce the rate of corrosion.
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Keywords
R. Usop, Z.H.Z Abidin, N.A. Mazni, A.N. Hadi, N.A. Halim, R.M. Taha, M.A. Careem, S.R. Majid and A.K. Arof
This paper aims to study the colour stability of chlorophyll and the effect of copper (II) nitrate – Cu(NO3)2 – as an additive in natural dye coating films after being exposed to…
Abstract
Purpose
This paper aims to study the colour stability of chlorophyll and the effect of copper (II) nitrate – Cu(NO3)2 – as an additive in natural dye coating films after being exposed to ultraviolet-A (UV-A).
Design/methodology/approach
The natural dye was extracted from the leaves of Cassia alata L. using absolute ethanol as the solvent. The extract was divided into two parts and, one of it was added with 3 wt.% Cu(NO3)2 as an additive. The polymer blend of poly(methyl methacrylate) (PMMA) and acrylic polyol was used as the coating binder. Both parts of the dye with and without additive were mixed with the blended polymer in a specific ratio. The resulted mixtures were applied as coating films on glass substrates. The colour stability of the coating films on exposure to UV-A with the time of exposure was observed with Commission internationale de l’éclairage (CIE) L*a*b* colour coordinates. The hidden power by the means of reflectivity and glossiness of the coatings was also studied. Statistical standard deviation (STD) was used to analyse the data.
Findings
The test showed that the coating films containing Cu(NO3)2 had smaller colour differences, (ΔE*) indicating higher colour stability. The analysis on hidden power also showed that the coating film with Cu(NO3)2 was 1.6 times more stable than the film without additive. All the measurements in this study were observed within 35 days of duration.
Research limitations/implications
This paper implies the potential of using natural dye extracted from Cassia alata L. leaves as a stable dye colourant for coating applications.
Practical implications
The coating film developed in this study is suitable for glass substrate applications.
Originality/value
A new method of preparing solvent-based coating film from PMMA–acrylic polyol with chlorophyll colourant is introduced in this study.
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Z.H.Z. Abidin, N.S.A. Manah, A.N. Hadi, N.S. Saugi, F.A. Fuad, N.A. Mazni, H.C. Hassan, M.A. Careem and A.K. Arof
This paper aims to focus on a comparison study of the visible stability of natural blue dye consisting anthocyanin molecules extracted from Clitoria ternatea in coating films.
Abstract
Purpose
This paper aims to focus on a comparison study of the visible stability of natural blue dye consisting anthocyanin molecules extracted from Clitoria ternatea in coating films.
Design/methodology/approach
The coating films were prepared by mixing the blue dye with poly(acrylamide-co-acrylic acid) in three different weight ratios. Samples were coded as 10PBA, 15PBA and 20PBA, where PBA is the abbreviation for poly acrylamide-co-acrylic acid, blue dyes and anthocyanin. The number at the beginning of each code represents the weight percentage of poly(acrylamide-co-acrylic acid) to natural blue dye. The mixtures were applied on separate glass substrates to form coating films. Another set of samples were prepared for the comparison study with a commercial acrylic clear coat (cc) applied on the surface of the 10PBA, 15PBA and 20PBA coating films. These coating films were coded 10PBAcc, 15PBAcc and 20PBAcc. The purpose of the clear coat is to observe how it affects the colour stability of the blue coating films with respect to time. All samples were exposed to the ultraviolet (UV) source, an 18 W Philips TL-D 18w/830 UV fluorescent lamp. The UV lamp was placed 15 cm above the surface of the samples for 35 days. The colour of the coatings was measured using CIE L*a*b* colour space coordinate.
Findings
The results obtained show 10PBA and 10PBAcc have the highest colour stability after 35 days of exposure to UV light. The reflectivity of the coating films was also measured during exposure to UV lamp. Reflectivity measurements also showed that 10PBA and 10PBAcc coating films had the highest reflective stabilities.
Research limitations/implications
The potential of using natural blue dye consisting anthocyanin in coating film to obtain high colour stability.
Practical implications
The coating film developed in this work is suitable to be applied on glass substrates.
Originality/value
The application of anthocyanin dye extracted from the Clitoria ternatea L. as a colourant in coating films
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Xiangbin Liu, Fandi Meng, Ruiping Liu, Junlin Kou, Zeyang Zhang, Jianrong Feng, Li Liu and Fuhui Wang
The marine environment presents a great challenge to the anticorrosion properties of organic coatings applied on equipment. Since the compactness of coatings is critical in marine…
Abstract
Purpose
The marine environment presents a great challenge to the anticorrosion properties of organic coatings applied on equipment. Since the compactness of coatings is critical in marine environments, a novel nepheline-epoxy resin (N-EP) composite was introduced into organic coatings to improve the interfacial compatibility between the pigments and the binder. The purpose of this study is to evaluate the effectiveness of the N-EP composite in enhancing the corrosion resistance of the coatings in marine conditions.
Design/methodology/approach
These composite particles were prepared via the mechanical ball milling method at thermofield-assisted, leading to chemical bonding between inorganic nepheline and epoxy resin, the agglomeration of particles was avoided by this method. Fourier transform infrared spectroscopy, transmission electron microscope, particle size distribution, sedimentation and thermogravimetric-differential thermal analysis were used to verify the feasibility of thermal field-assisted mechanochemistry for achieving a direct reaction between epoxy resin and nepheline powder, as well as to determine the optimal reaction conditions. Additionally, water absorption tests, Electrochemical impedance spectroscopy and scanning electron microscope were conducted to assess the anticorrosive properties of the modified nepheline coatings.
Findings
The results further indicated that N-EP improved the barrier performance and mechanical properties of the coating. For example, after modified, the tensile strength of coating had increased from 41.96 ± 0.05–63.14 ± 0.05 MPa. This can be attributed to the less defective N-EP/binder interface and the uniform dispersion of N-EP in the coating. The optimal preparation conditions (500 r/min of ball grinding speed and 6 h of ball grinding time) for the composites were also studied for a superior corrosion resistance of the coating.
Originality/value
Thermofield-assisted mechanochemistry enables direct reactions between epoxy resin and nepheline powder, enhancing the dispersion stability and interfacial compatibility of N-EP. This modification improves coating compactness, reduces porosity and enhances corrosion resistance by strengthening the labyrinth effect on water diffusion.
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Keywords
Dmitry Leonidovich Kovalenko, Vy Uong Van, Van Phuc Mac, Thien Vuong Nguyen, Lan Pham Thi, Tuan Anh Nguyen, Vladimir Evgenevich Gaishun, Vasili Vasilievich Vaskevich and Dai Lam Tran
This paper aims to explore how graphene can improve the mechanical and anti-corrosion properties of TiO2-SiO2 sol-gel coating. This sol-gel coating has been prepared on aluminum…
Abstract
Purpose
This paper aims to explore how graphene can improve the mechanical and anti-corrosion properties of TiO2-SiO2 sol-gel coating. This sol-gel coating has been prepared on aluminum alloy substrate using graphene as both nano-filler and corrosion inhibitor.
Design/methodology/approach
To examine the effect of graphene on mechanical properties of sol-gel coating, the abrasion resistance, adhesion strength and scratch resistance of coating have been evaluated. To reveal the effect of graphene on the anti-corrosion property of coating for aluminum alloy, the electrochemical impedance spectroscopy (EIS) has been conducted in 3.5 Wt.% NaCl medium.
Findings
Scanning electron microscopy images indicate that graphene nanoplatelets (GNPs) have been homogeneously dispersed into the sol-gel coating matrices (at the contents from 0.1 to 0.5 Wt.%). Mechanical tests of coatings indicate that the graphene content of 0.5 Wt.% provides highest values of adhesion strength (1.48 MPa), scratch resistance (850 N) and abrasion strength (812 L./mil.) for the sol-gel coating. The EIS data show that the higher content of GNPs improve both R1 (coating) and R2 (coating/Al interface) resistances. In addition to enhancing the coating barrier performance (graphene acts as nanofiller/nano-reinforcer for coating matrix), other mechanism can be at work to account for the role of the graphene inhibitor in improving the anticorrosive performance at the coating/Al interface.
Originality/value
Application of graphene-based sol-gel coating for protection of aluminum and its alloy is very promising.
Ioannis A. Kartsonakis, Andronikos C. Balaskas and George C. Kordas
The purpose of this paper is to focus on the corrosion protection of magnesium alloy ZK10 by applying via the dip‐coating process an hybrid organic‐inorganic coating that contains…
Abstract
Purpose
The purpose of this paper is to focus on the corrosion protection of magnesium alloy ZK10 by applying via the dip‐coating process an hybrid organic‐inorganic coating that contains nanocontainers of TiO2 loaded with corrosion inhibitor.
Design/methodology/approach
The coating consists of cross‐linked polymers containing epoxy groups, conductive polymer polypyrrole as well as organic modified silicates. The morphology and the composition of the coating were examined with scanning electron microscopy and energy dispersive X‐ray analysis, respectively.
Findings
Corrosion tests via electrochemical impedance spectroscopy denoted that the incorporation of loaded nanocontainers improved the anticorrosion properties of the coating by increasing the impedance values in the low frequency range. Moreover, the surface of the aforementioned coating remained crack free after the exposure of the sample to corrosive environment.
Originality/value
The paper presents a new system which has been developed for the corrosion protection of magnesium alloy ZK10.
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Tongyan Pan and Qifeng Yu
This study aims to present the fabrication of the two-layer system, coating it on steel surface and evaluating the system’s anti-corrosion performance using the ASTM Standard…
Abstract
Purpose
This study aims to present the fabrication of the two-layer system, coating it on steel surface and evaluating the system’s anti-corrosion performance using the ASTM Standard Salt-Spray Test: B117 and the technique of Electrochemical Impedance Spectroscopy (EIS).
Design/methodology/approach
A synthesized electroactive polyaniline (PANi) was utilized in this study to make a PANi-based primer, with which a two-layer coating system was fabricated by overlaying the primer with a polyurethane top-coat.
Findings
In the Salt-Spray test, the two-layer PANi/polyurethane system exhibited higher corrosion resistance than the two-layer control epoxy/polyurethane system. In particular, the PANi/polyurethane system tended to mitigate the production of rust on substrate surface and demonstrated higher delamination resistance. The EIS analysis confirmed the high corrosion resistance and delamination resistance of the two-layer PANi/polyurethane system based on parameters obtained using the best-fit equivalent circuits.
Practical implications
The demonstrated anti-corrosion capacity of this new PANi/polyurethane system laid a solid base for industrial applications.
Originality/value
This novel coating system is expected to achieve improved corrosion protection for steels than the conventional zinc-rich three-layer coatings.
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Guiyang Wu, Qiang Zhang and Nange Zhang
Organic coatings are one of the most widely applied methods for corrosion protection of metallic materials such as the tubing used in sour gas field. However, such coatings…
Abstract
Purpose
Organic coatings are one of the most widely applied methods for corrosion protection of metallic materials such as the tubing used in sour gas field. However, such coatings usually encounter the risk of failure due to the harsh and complex environment. Therefore, the study of failure of the organic coating is highly significant.
Design/methodology/approach
In this paper, the effects of Cl-concentration, HCl content, hydrogen sulfide/carbon dioxide (H2S/CO2), temperature and flow rate on the failure of epoxy-phenolic coating on the internal surface of BG90S steel tubing were investigated using adhesion force measurement, metallographic microscope, electrochemistry impedance spectroscopy and Fourier transform infrared spectroscopy.
Findings
The results show that the Cl-concentration, HCl content and H2S/CO2 do not affect the failure process too much as the ion concentration increased. However, the flow rate at the high temperature is the most important factor affecting the corrosion resistance of the inner coating tubing. With the increase of the flow rate, the pore resistance of the coating shows a decreasing trend, and the rate of decrease in pore resistance is first rapid and then slow. It demonstrates that the penetration speed of the electrolyte solution into the coating varied from fast to slowly. A weakening influence of the flow rate on the penetration failure of the inner coating can be found as the increase of the flow rate. Once the HS-ions penetrate through the coating and reach at the coating/steel interface where H2 could be formed through the adsorption reaction, the coating failure occurs.
Originality/value
The failure of the coating depends on the penetration rate of water and ions, with the presence of exposed or punctured holes is accelerated and HS- was adsorpted by substrate Fe, and form H2 molecules between the coatings and substrate, that results failure of coatings.
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Thien Vuong Nguyen, Vy Do Truc, Tuan Anh Nguyen and Dai Lam Tran
This study aims to explore the synergistic effect of oxide nanoparticles (ZnO, Fe2O3, SiO2) and cerium nitrate inhibitor on anti-corrosion performance of epoxy coating. First…
Abstract
Purpose
This study aims to explore the synergistic effect of oxide nanoparticles (ZnO, Fe2O3, SiO2) and cerium nitrate inhibitor on anti-corrosion performance of epoxy coating. First, cerium nitrate inhibitors are absorbed on the surface of various oxide nanoparticles. Thereafter, epoxy nanocomposite coatings have been fabricated on carbon steel substrate using these oxide@Ce nanoparticles as both nano-fillers and nano-inhibitors.
Design/methodology/approach
To evaluate the impact of oxides@Ce nanoparticles on mechanical properties of epoxy coating, the abrasion resistance and impact resistance of epoxy coatings have been examined. To study the impact of oxides@Ce nanoparticles on anti-corrosion performance of epoxy coating for steel, the electrochemical impedance spectroscopy has been carried out in 3% NaCl solution.
Findings
ZnO@Ce3+ and SiO2@Ce3+ nanoparticles provide more enhancement in the epoxy pore network than modification of the epoxy/steel interface. Whereas, Fe2O3@Ce3+ nanoparticles have more to do with modification of the epoxy/steel interface than to change the epoxy pore network.
Originality/value
Incorporation of both oxide nanoparticles and inorganic inhibitor into the epoxy resin is a promising approach for enhancing the anti-corrosion performance of carbon steel.
Kong Dejun and Li Jiahong
The purpose of this paper is to evaluate the salt spray corrosion (SSC) and electrochemical corrosion performances of CrNi, TiAlN/NiCr and CrNi–Al2O3–TiO2 coatings on H13 steel…
Abstract
Purpose
The purpose of this paper is to evaluate the salt spray corrosion (SSC) and electrochemical corrosion performances of CrNi, TiAlN/NiCr and CrNi–Al2O3–TiO2 coatings on H13 steel, which improved the corrosion resistance of H13 hot work mold.
Design/methodology/approach
CrNi, TiAlN/NiCr and CrNi–Al2O3–TiO2 coatings were fabricated on H13 hot work mold steel using a laser cladding and cathodic arc ion plating. The SSC and electrochemical performances of obtained coatings were investigated using a corrosion test chamber and electrochemical workstation, respectively. The corrosion morphologies, microstructure and phases were analyzed using an electron scanning microscope, optical microscope and X-ray diffraction, respectively, and the mechanisms of corrosion resistance were also discussed.
Findings
The CrNi coating is penetrated by corrosion media, producing the oxide of Fe3O4 on the coating surface; and the TiAlN coating is corroded to enter into the CrNi coating, forming the oxides of TiO and NiO, the mechanism is pitting corrosion, whereas the CrNi–Al2O3–TiO2 coating is not penetrated, with no oxides, showing the highest SSC resistance among the three kinds of coatings. The corrosion potential of CrNi coating, TiAlN/CrNi and CrNi–Al2O3–TiO2 coatings was –0.444, –0.481 and –0.334 V, respectively, and the corresponding polarization resistances were 3,074, 2,425 and 86,648 cm2, respectively. The electrochemical corrosion resistance of CrNi–Al2O3–TiO2 coating is the highest, which is enhanced by the additions of Al2O3 and TiO2.
Originality/value
The CrNi, TiAlN/CrNi and CrNi–Al2O3–TiO2 coatings on H13 hot work mold were firstly evaluated by the SSC and electrochemical performances.