Graphene Composite Coatings Research Articles

Research on the Optimal Protection Parameters of Graphene Composite Conductive Coatings Combined with Impressed Current Cathodic Protection Technology in Marine Atmospheric Environments

Based on the principle of a micropore-filling electrolyte, a graphene composite conductive coating combined with impressed current cathodic protection (ICCP) technology was constructed and applied in a marine atmospheric environment. To further explore the optimal protection parameters of the graphene composite conductive coating combined with ICCP technology in a marine atmospheric environment, the effects of the coating damage area (A), impressed voltage (B), and distance from the contact point (C) on the protective performance of the coating were investigated via orthogonal experiments. The optimal protection voltage and effective protection distance were verified by super-depth-of-field morphology observations and electrochemical tests. The orthogonal experimental results show that the primary and secondary orders affecting the protective performance of the conductive graphene composite coating are as follows: applied voltage (B) > coating damage area (A) > distance from the point of contact (C). The optimal protective parameters of the coating in the marine atmospheric environment are an applied voltage of 0.7 V, a damage rate of ≤1%, and a distance from the point of contact of 190 mm. The experimental results show that the corrosion potential of the sample is the highest under an applied voltage of 0.7 V, and the corrosion products do not diffuse to the surface of the coating. When the polarization resistance (Rp) values at 110 mm and 190 mm from the negative electrode at the point of contact are greater, the corrosion rate is lower, and the coating protection performance is better.

Optimization strategies for graphene-based protection coatings: a review

Abstract Graphene has become an emerging and promising option in the field of protection coating for anti-corrosion due to its specific properties in chemical inertia and physical impermeability. It can be applied to metal protection coating in forms of either atomically thin films or composite materials, known, respectively, as pure chemical vapour deposition (CVD) graphene coatings and graphene composite coatings (GCCs). Nonetheless, various structure defects, synthesis imperfections and graphene’s positive potential to metals would make graphene-based protective coatings tend to exhibit corrosion promotion by arousing micro-galvanic corrosion, largely undermining its anti-corrosion efficiency. Based on this, many optimization strategies and methods have been conceived and applied to the graphene-based protection coatings in these two aspects for improving its anti-corrosion efficiency. For example, a good dispersion and orderly arrangement of graphene derivatives in the GCCs can largely optimize its anti-corrosion performance. Here, this paper separately reviews detailed optimization strategies, corresponding mechanisms and key factors for the use of representative graphene-based materials in these two aspects, with the aim of providing comprehensive knowledge and a roadmap of developing cheap, powerful and effective barrier technologies. Finally, perspectives on opportunities and challenges in improving the barrier coating efficiency of graphene-based materials are discussed.

Anti-icing properties and application of superhydrophobic coatings on asphalt pavement

In regions impacted by snow and ice, icy road surfaces can significantly reduce road capacity and endanger vehicle occupants. While traditional de-icing methods, such as spreading de-icing salt and mechanical de-icing, have drawbacks such as environmental pollution and damage to road facilities, superhydrophobic coating is gaining attention as a new, environmentally friendly, and efficient anti-icing method. Superhydrophobic coating can reduce the adhesion between the ice layer and the road surface, so as to achieve the purpose of road anti-icing in a low environmental impact way. To improve the anti-icing performance of asphalt pavement under low-temperature and humid conditions and reduce the impact of snow and ice freezing disaster, we prepared nano-SiO2 superhydrophobic coatings(SSC) and nano-SiO2/graphene composite superhydrophobic coatings(SGSC) using aqueous epoxy resins, hydrophobic nano-SiO2, and sparsely layered graphene as raw materials. The coatings' wettability, ice resistance, and road performance were analyzed. The study found that the contact angles of the SSC and SGSC were 151.2° and 153.0°, respectively. The BPN value of the SGSC decreased by 12.6% after application to the asphalt pavement, but it still meets safety requirements. The coating also maintains a certain degree of ice-resistant performance within five freeze-thaw cycles. The study results indicate that superhydrophobic coatings have the potential to improve pavement ice resistance.

Co-deposition and thermal conductivity of nickel–graphene composite coatings on copper surface

Co-deposition and thermal conductivity of nickel–graphene composite coatings on copper surface

A new type of high hardness coating for improving drill bit stability in unconventional oil and gas development

In deep unconventional oil and gas development, the problem faced is that PDC bits are eroded by solid-liquid high-speed fluids, resulting in damage. It has led to serious damage to the stability of the drill bit, a decrease in the service life of the drill bit, and an increase in the difficulty in efficient drilling. The essence is that the surface hardness and erosion resistance of the drill bit are not strong enough. Therefore, improving the stability of drill bits is a crucial and urgent problem to be solved. In this paper, Ni60A + 20% WC + 0.3% graphene composite coatings were prepared on a Q235 steel substrate, which is a new type of high hardness coating. Moreover, the effects of microstructure and microhardness of the composite coatings at different laser powers (800 W, 1200 W, 1600 W, and 2000 W) were investigated. The results show that the laser power can significantly affect the microstructure of the coating. The phase composition of the composite coatings is essentially the same at different laser powers. However, there are significant differences in the content of each phase. When the laser power is higher than 1200W, the content of M23C6, Cr3C2 and Fe3C in the composite coating increases and the microhardness of the coating decreases. When the laser power is below 1200 W, the dilution rate of the substrate is low and a metallurgical bond cannot be formed between the composite coating and the substrate.

Graphene composite self-healing antifog/frost-resist transparent coatings with zwitter-wettability

Self-healing materials achieve both durability and simplified maintenance by restoring their structure and function. However, self-healing materials utilizing surface hydrophilicity are considered incompatible with zwitter-wettability properties. Therefore, further investigation is needed to fabricate antifogging coatings that combine zwitter-wettability and self-healing properties. In this study, we demonstrated that polymer multilayer graphene composite coatings exhibit simultaneous antifogging and self-healing properties. We achieved a uniform dispersion of an aqueous solution of graphene by directly dispersing in a strong acid polymer and a uniform dispersion of graphene in the membrane via layer-by-layer self-assembly without any post-treatment, enabling precise control of hydrophobicity and water absorption of the membrane. The fabricated layer-by-layer coatings exhibited zwitter-wettability and self-healing performances comparable to those of previously reported systems. The maximum water droplet contact angle on the surface was 99° The 20-bilayer coating also exhibited excellent self-healing performance, closing 100 μm scratches within approximately 60 s and flattening the surface within approximately 300 s of exposure to water. In the antifogging tests, the coatings demonstrated high resistance to harsh cooling environments and exhibited excellent antifogging performance. This study provides a new zwitter-wetting strategy that combines self-healing and antifogging properties, providing an exceptional option for the development of next-generation surface coatings.

SiC nanowires enhanced graphene composite coatings with excellent tribological and anticorrosive properties

The synergistic effect between nanomaterials with different dimensions can enhance wear and corrosion resistance of surface protective coatings. In this work, GO-pva-SiC and RGO-pva-SiC coatings were constructed on stainless steel substrate by combining spraying process and subsequent chemical reduction of hydrazine hydrate. Tribological tests have shown that GO-pva-SiC coating exhibits good lubricating performance under low load and long wear life under high load. After reduction, RGO-pva-SiC coating presents a longer wear resistance life (25,000 cycles) at a lower friction coefficient of 0.11 under 20.0 N. Furthermore, the electrochemical corrosion behavior indicates that the addition of SiC NWs can enhance corrosion resistance of graphene-based coatings. This work provides an efficient way to develop graphene-based composite coatings for practical engineering applications.

Improvement of corrosion resistance and research on corrosion mechanism after depositing Ni–Y2O3/Ni–graphene composite coatings on NdFeB magnets

In this work, the authors studied the corrosion resistance of composite deposits of yttrium (III) oxide (Y2O3) and graphene on a nickel (Ni) coating. The corrosion resistance of the coating was significantly improved after the composite deposition, particularly for the nickel–graphene coating with the addition of 0.05 g/l graphene. The E corr and I corr of the coating were optimized to 404.340 mV and 0.24 × 10−8 A/cm2, respectively. The surface morphology, microstructure, passivation behavior and corrosion products of the coating were analyzed, and the mechanism of corrosion resistance enhancement was revealed. The results show that deposition of the yttrium (III) oxide and graphene composite can decrease the surface roughness of the coating. The graphene composite has a more significant effect and greatly reduces the contact area between the coating and the medium. Moreover, particle composite deposition can also lead to grain refinement. Graphene composite deposition reduces the grain size from 75.3 to 18.9 nm, significantly improving the nucleation and formation of the passivation film. Uniform deposition of graphene at grain boundaries can also hinder the infiltration of corrosive media into the interior region. Upon composite deposition, the improved corrosion resistance of magnets significantly increases their performance and service life, facilitating their railway applications.

Fabrication of Metal/Graphene Composites via Cold Spray Process: State-of-the-Art and the Way Forward

Cold spray (CS)-fabricated metal–graphene composites have applications in several fields ranging from tribology and corrosion protection to antibacterial applications. However, it is critical from a process perspective to create a viable feedstock, and to this end, there are two widely reported techniques: ball milling and in situ reduction. In this paper, the CS feedstocks prepared via these two methods are compared and contrasted with other miscellaneous techniques in the literature based on their efficacies and the end properties of the fabricated coatings. CS metal–graphene composite coatings are found to display self-healing behaviour and excellent corrosion/wear resistance and mechanical properties, but at this juncture, there is a gap in the literature as far as the CS fabrication of self-standing metal–graphene composite parts is concerned. Several future research avenues are discussed to fully comprehend the printability and functionality of metal/GNP composite cold-sprayed structures.

A facile approach to fabricating graphene/waterborne epoxy coatings with dual functionalities of barrier and corrosion inhibitor

• A facile approach to fabricating C-G/WEP and S-G/WEP composite coatings with dual functionalities as barriers and corrosion inhibitors was developed. • The impedance of the C-G/WEP and S-G/WEP coatings is enhanced by more than two orders of magnitude compared with that of WEP coatings. • The presence of surfactants facilitates the dispersion of C-G and S-G nanosheets in both the solution and the composite coatings. • The surfactants endow inhibition ability of the coatings, thereby the composite coatings effectively protect the underlying Q235 steel against corrosion. • This work exemplifies a facile yet environmentally-friendly approach to preparing graphene composite coatings and may enable the large-scale production of graphene anticorrosion coatings. A facile and environmentally-friendly method is developed to prepare graphene/waterborne epoxy (WEP) composite coatings. The graphene nanosheets are produced with electrochemical-exfoliation in the solution containing surfactants, cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). The nanosheets containing solution thus formed are subjected to a quick dialysis and then directly used as a diluent for WEP without any further treatment. This preparation method overcomes the commonly identified problems of aggregations and ‘corrosion promotion’ effect associated with graphene, and increases the impedance of the composite coatings by more than two orders of magnitude. The analysis of anticorrosion performance suggested that the presence of surfactants not only improves the dispersibility of graphene nanosheets but also endows the composite coatings with both barrier and corrosion inhibition capabilities. The strategy reported herein may pave the path to the large-scale production of graphene anticorrosion coatings.

Bio-inspired Multifunctional Graphene-Epoxy Anticorrosion Coatings by Low-Defect Engineered Graphene.

Although graphene has been regarded as the most ideal anticorrosion filler, to date, some vital problems including poor dispersion, disordered arrangement, structure defects, and galvanic corrosion remain unresolved,, thus blocking its potential application in metal protection. In this work, a bio-inspried multilayered graphene-epoxy composite coating was fabricated through a scalable spraying approach with well-dispersed low-defect engineered graphene as the functional filler. Polydopamine served as an enforcer to improve the dispersity and repair the structure defects of graphene (π-π interaction) and bridged the dense graphene layers and epoxy layers (strong adhesion) for forming "interlock" structures to ensure complete coating systems. Electrochemical tests confirmed that the bio-inspired composite coating showed elevated coating resistance from 4.2 × 106 Ω cm2 for blank coating and 2.5 × 108 Ω cm2 for blending composite coating to 3.0 × 109 Ω cm2. The highly anisotropic graphene layers endowed the bio-inspried coating with highly anisotropic thermal and electrical conductivities, with the in-plane and through-plane thermal conductivities being 0.78 and 0.21 W/mK, respectively. Besides, the good anisotropic conductivities make the bio-inspired coating achieve self-monitoring of structural safety and health. This bio-inspired strategy provides a fascinating method for constructing high-performance graphene composite coatings with functional properties.

Atomistic simulation on frictional response of nanoscratched Al–graphene system

Frictional behaviors of graphene, which have been generally investigated on elastic or rigid substrates, are carefully discussed here in metal–graphene systems through molecular dynamics simulations. The nanoscratched process and topography analysis are conducted to study the friction on a composite surface, where the layer number, embedding depth, and interval of graphene are considered as major factors. The friction coefficient of monolayer graphene on an Al surface is obviously higher than the reported results on an elastic or rigid substrate, while the variety of substrates seems to make no much difference to frictional results on multilayer graphene. Graphene is actually helpful for reducing friction on composite surfaces, but the friction coefficient on composite surfaces will rocket from 0.045 to 0.835 with the rise in the embedding depth of graphene, and this range of data is consistent with experimental values measured on Al–graphene composite coatings. Moreover, a larger distance between graphene may lead to an increase in the overall friction coefficient, which can also be proved by electroplating experiments under a low concentration of graphene.

A Review of Graphene-Based Materials for Marine Corrosion Protection

Graphene-based anti-corrosion materials exhibit excellent chemical inertness and impermeability and are promising and emerging materials for the protection of metals. In this review, the recent progress in the production of graphene-based materials for protection against marine corrosion is discussed. Major mechanisms of marine corrosion and strategies for corrosion protection are illustrated. The properties and methods used for the preparation (micromechanical stripping method and chemical vapor deposition) of graphene are introduced. Two fabrication strategies for graphene-based corrosion protection materials are presented. For pure graphene films, fewer defects and low conductivity lead to the enhancement of anti-corrosion properties. For graphene composite coatings, improving the dispersibility of graphene in the coating matrix and strengthening the durability render graphene coatings to be more effective for marine corrosion protection. Insulation is highly desirable for avoiding electrochemical reactions to protect against heavy marine corrosion in the later stages. Finally, we provide perspectives on the future of graphene-based materials for marine corrosion protection, anticipating that a properly prepared graphene composite coating can serve as a long-term anti-corrosive material for marine applications.

Microstructure and properties of rare earth CeO2-doped graphene composite coatings prepared by MAO on AA7050

Abstract In this paper, ceramic coatings were prepared on the surface of 7050 high strength aluminum alloy using a micro-arc oxidation process in a silicate electrolyte combined with the rare earth element cerium or graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, and electrochemical measurements were used, respectively. It was shown that the micropore size of the composite coatings, which mainly consisted of α-Al2O3 and γ-Al2O3, decreases and the density improved with the simultaneous addition of 4 g · L-1 of CeO2 and 10 g · L-1 of graphene to the electrolyte. In addition, with the addition of CeO2 and graphene, the roughness was the lowest and the corrosion resistance was significantly improved.

Microstructure and properties of rare earth CeO2-doped graphene composite coatings prepared by MAO on AA7050

Abstract In this paper, ceramic coatings were prepared on the surface of 7050 high strength aluminum alloy using a micro-arc oxidation process in a silicate electrolyte combined with the rare earth element cerium or graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, and electrochemical measurements were used, respectively. It was shown that the micropore size of the composite coatings, which mainly consisted of α-Al2O3 and γ-Al2O3, decreases and the density improved with the simultaneous addition of 4 g · L-1 of CeO2 and 10 g · L-1 of graphene to the electrolyte. In addition, with the addition of CeO2 and graphene, the roughness was the lowest and the corrosion resistance was significantly improved.

Al2O3 + Graphene Low-Friction Composite Coatings Prepared By Sol–Gel Method

In this work, Al2O3 + graphene coatings were prepared using the sol–gel method. The aim of the study was preliminary determination of the influence of size and amount of graphene nanoplatelets on morphology, chemical structure, and basic tribological properties of Al2O3 + graphene composite coatings. Two types of reduced graphene oxide (rGO) nanoplatelets with different lateral size and thickness were used to prepare the coatings. To characterize them, scanning electron microscope (SEM), glow discharged optical emission spectrometer (GDOES), Fourier-transform infrared (FTIR), reflectance spectrometer, and ball-on-disk tribological tests were used. It was found that the presence of graphene in the Al2O3 + graphene coatings did not fundamentally change the chemical transformation of ceramic Al2O3 matrix. Morphology examinations of coatings containing larger graphene nanoplatelets revealed a tendency to their parallel arrangement in relation to the coated surface. The tribological properties of Al2O3 + graphene coatings turned out to be strongly dependent on the size of graphene nanoplatelets as well as on the heat treatment temperature. The friction coefficient as low as 0.11 and good durability were obtained for the Al2O3 + graphene coating with larger nanoplatelets and heat-treated at 500 °C. The results of conducted research indicate the potential use of Al2O3 + graphene composite coatings prepared by the sol–gel method as low-friction ceramic coatings.

Structure and Properties of Ni-B/Graphene Oxide Composite Coatings Produced by Chemical Reduction Method

A nickel-boron (Ni-B)/graphene composite coatings were produced using chemical reduction method on a steel substrate. These composites were compared to Ni-B coatings without graphene embedded into the matrix. Graphene in the form of an aqueous suspension of graphene oxide flakes was used. Graphene was characterized by single-layered flakes about 0.5 µm in size. The coatings produced were characterized by an amorphous structure. The incorporation of graphene into the Ni-B matrix affects the surface topography and morphology of the coatings produced. The addition of graphene strengthened the coating material. An increase in the hardness (~ 1100 HK0.025) was noted for Ni-B/graphene composite coatings compared to the hardness (~ 950 HK0.025) of the Ni-B coatings without a built-in dispersion phase. Composite coatings also exhibited a better corrosion resistance than the coatings without embedded graphene.

Effect of Graphene Oxide Concentration in Electrolyte on Corrosion Behavior of Electrodeposited Zn–Electrochemical Reduction Graphene Composite Coatings

Pure Zn and Zn–ERGO composite coatings were prepared by direct current electrodeposition on 304 stainless steel. Samples were characterized by X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS), and laser Raman spectroscopy (Raman). Results obtained have shown that the concentration of GO sheets in zinc sulfate electrolyte has an important effect on the preferred crystal orientation and the surface morphology of Zn–ERGO composite coatings. A study of the corrosion behavior of the coatings by Tafel polarization and electrochemical impedance spectroscopic (EIS) methods leads to the conclusion that the Zn-1.0 g/L ERGO composite coating possesses the best corrosion resistance compared to the pure Zn coating and other composite coatings in this study.

Electrophoretic‐Deposition of Graphene and Microstructure and Friction Behavior of Ni–Graphene Composite Coatings

Ni–graphene composite coatings with promising friction reduction and wear resistance are successfully deposited on magnesium alloys substrate by an integrative approach involved electrophoresis and pulse electrodeposition. The optimization parameters for electrophoretic deposition are explored extensively. The effect of duty cycle on microstructure, micro‐indentation hardness, friction, and tribological properties for Ni–graphene composite coatings are investigated. The Ni matrix exhibits most refined at 60% duty cycle according to surface micrographs of the Ni–graphene composite coatings. The cross‐section microstructure and line energy spectra proves that the Ni–graphene coating is deposited on the substrates successfully and is physically bonded to the substrates. The peak value of micro‐indentation hardness about 181.78 HV at 60% is achieved. The lowest friction coefficient and minimal wear loss of Ni–graphene composite coatings are obtained at 60% duty cycle, indicating optimal friction reduction and wear resistance performance.

Exploring the Nickel–Graphene Nanocomposite Coatings for Superior Corrosion Resistance: Manipulating the Effect of Deposition Current Density on its Morphology, Mechanical Properties, and Erosion‐Corrosion Performance

The use of graphene‐based composite as anti‐corrosion and protective coatings for metallic materials is still a provocative topic worthy of debate. Nickel–graphene nanocomposite coatings have been successfully fabricated onto the mild steel by electrochemical co‐deposition technique. This research demonstrates the properties of nickel–graphene composite coatings influenced by different electrodeposition current densities. The effect of deposition current density on the; surface morphologies, composition, microstructures, grain sizes, mechanical, and electrochemical properties of the composite coatings are executed. The coarseness of deposited coatings increases with the increasing of deposition current density. The carbon content in the composite coatings increases first and then decreases by further increasing of current density. The improved mechanical properties and superior anti‐corrosion performance of composite coatings are obtained at the peak value of current density of 9 A dm−2. The incorporation of graphene sheets into nickel metal matrix lead to enhance the micro hardness, surface roughness, and adhesion strength of produced composite coatings. Furthermore, the presence of graphene in composite coating exhibits the reduced grain sizes and the enhanced erosion–corrosion resistance properties.