Good Anti-corrosion Performance Research Articles

Bio-Based Waterborne Polyurethane Coatings with High Transparency, Antismudge and Anticorrosive Properties.

Green and environment-friendly preparation are of the utmost relevance to the development of transparent antismudge coatings. To prepare a waterborne polyurethane (WPU) coating with antismudge property, it is challenging to balance the stability of dispersion and the antismudge property of coating. Herein, we prepare a transparent bio-based WPU coating grafted with a minor proportion of poly(dimethylsiloxane) (WPU-g-PDMS) using renewable castor oil, monocarbinol-terminated PDMS, hexamethylene diisocyanate trimer, and 2,2-bis(hydroxymethyl)propionic acid as raw materials. Effects of the dosage of monocarbinol-terminated PDMS, the curing temperature, and the curing time on the antismudge performance were studied. Results showed that rigorous stirring (3000 rpm) is necessary to obtain a stable WPU-g-PDMS dispersion with a storage time longer than 6 months. A high curing temperature (>160 °C) and a period of curing time (>1 h) are indispensable to obtain the excellent antismudge property because they would facilitate the grafted low-surface-tension PDMS chains to migrate from the interior to the coating surface. The facts that simulated contaminated liquids such as water, HCl solution, NaOH solution, artificial blood, and tissue fluid could slide off easily and cleanly, and marker ink lined on the coating surface could shrink, indicated that the WPU-g-PDMS coating has good antismudge properties, which could be self-compensated shortly after deterioration. Due to the high cross-linking degree caused by multifunctional polyol and isocyanate, the WPU-g-PDMS coating has high hardness and good anticorrosive performance. The antismudge functionalization and waterborne technology of bio-based polyurethane coatings proposed in this work could be a promising contribution to the green and sustainable development of functional coatings. This kind of WPU-g-PDMS coating is expected to protect and decorate electronic screens, vehicles, and buildings, especially endoscopes.

Self-healing performance and corrosion resistance of a bilayer calcium carbonate coating on microarc-oxidized magnesium alloy

A CaCO3 coating with good anticorrosion and self-healing performance was fabricated on the as-prepared MAO coating on the surface of AZ41 Mg alloy via ultrasound-assisted chemical conversion, a DCPD(CaHPO4·H2O) coating was also fabricated on the MAO coating as a comparison. Surface characterizations were carried out to obtain the morphology and composition of CaCO3 coating formed and electrochemical methods were adopted to assess the corrosion resistance of Mg alloy embedded in PC paste. The self-healing property of MAO/CaCO3 coating was ascribed to the formation of extra calcite. This coating may become a potential target for surface modification of magnesium alloy formwork.

Characteristics of (Mo-Ta-W)-C and (Nb-Ta-W)-C refractory multi-principal element carbide thin films by non-reactive direct current magnetron co-sputtering

The (Mo-Ta-W)-C and (Nb-Ta-W)-C carbide thin films were prepared by non-reactive magnetron co-sputtering. The (Mo-Ta-W)-C thin films exhibited the simple BCC structure with the strip-like surface morphologies and a double-layer structure for cross sections with a columnar upper layer and an featureless lower layer. In the (Mo-Ta-W)-C thin films, the metal-metal and metal-oxygen bonds were observed with no metal-carbon bonds. The carbon-carbon bonds were observed, indicating free carbon phases existed in the (Mo-Ta-W)-C thin films. The surface roughness of (Mo-Ta-W)-C thin films was small with Ra value of 3.11–3.74 nm. The hardness of (Mo-Ta-W)-C thin films was 32.6–33.5 GPa. The (Nb-Ta-W)-C thin films formed the amorphous structure. Different from (Mo-Ta-W)-C thin films, the metal-carbon bonds existed in the (Nb-Ta-W)-C thin films, except the metal-metal and metal-oxygen bonds. The C-C bonds were also observed, indicating free carbon phases existed in the (Nb-Ta-W)-C thin films. The surfaces of (Nb-Ta-W)-C thin films displayed a granular structure with Ra of 0.86–1.00 nm, and the cross sections exhibited a fine fibrous structure. The hardness values of (Nb-Ta-W)-C thin films ranged from 34.5 to 36.1 GPa with elastic modulus of 319.6–349.5 GPa. The corrosion current density and polarization resistance of (Nb-Ta-W)-C thin films were better than 304 stainless steel, indicating good anti-corrosive performance of (Nb-Ta-W)-C thin films. The (Nb23Ta21W23)C33 thin film had low reflectivity in the visible light band (300–800 nm), and high reflectivity in the near-infrared band (800–2500 nm), with the solar absorption ratio αs of 0.4577 and the infrared emissivity εH of 0.178.

Polyhedral oligomeric silsesquioxane grafted covalent organic frameworks for simultaneously improved tribological and corrosion resistance of epoxy coatings

In this work, polyhedral oligomeric silsesquioxane (POSS) was covalently grafted on 2D covalent organic framework of TpPa-1 through Schiff base reaction (POSS-TpPa-1) to synergistically improve the corrosion and tribological resistance of epoxy coating. The results show that compared with the hydrophilic TpPa-1, POSS-TpPa-1 exhibits excellent hydrophobicity, and the water contact angle can reach 134°. Furthermore, POSS-TpPa-1 with different weight ratios was added into epoxy coating, and the anti-corrosion and wear resistance of the composite coatings were studied through electrochemical impedance spectroscopy (EIS) and friction and wear tests, respectively. The EIS results show that when the additive amount of POSS-TpPa-1 is 2 wt%, the impedance modulus in the low frequency region can maintain 1.04 × 109 Ω·cm2 even after being immersed in 3.5 wt% NaCl solution for 60 days, indicating its good anti-corrosion performance. The friction and wear experiments show that the epoxy composite coating with 2 wt% POSS-TpPa-1 exhibits the lowest friction coefficient of 0.23, suggesting that POSS-TpPa-1 can effectively improve the friction resistance of the coating under the premise of good dispersion. This work develops a new composite filler to simultaneously improve the anticorrosion and wear resistance of epoxy coating, which might be able to trigger further studies to develop more advanced composite coating by incorporating 2D-COF.

Preparation and Characterization of Graphene Oxide/Polyaniline/Polydopamine Nanocomposites towards Long-Term Anticorrosive Performance of Epoxy Coatings.

To address the challenging issues of metal materials corrosion in industries, which has caused huge economic losses and security threats to many facilities in marine environments, functional polymer coatings have been widely used and regarded as one of the simplest and most effective methods to prevent such an undesirable event. In this study, a new type of coating filler consisting of graphene oxide/polyaniline/polydopamine (GO-PANI-PDA) nanocomposites has been successfully synthesized. The morphology, structure, composition, and corrosion resistance performance of the GO-PANI-PDA (GPP) nanocomposites were investigated via a series of characterization methods. The results from our electrochemical impedance spectroscopy, potentiodynamic polarization curve and salt spray experiment showed that the best corrosion resistance performance of the coating is from GPP 21 with the epoxy/GO-PANI:PDA ratio of 2:1, which exhibited a positive corrosion potential (−0.51 V) shift from epoxy/GO-PANI coating (−0.64 V). The corrosion current density (3.83 × 10−8 A/cm2) of GPP 21 is nearly an order of magnitude lower than that of epoxy/GO-PANI (7.05 × 10−7 A/cm2). The good anti-corrosion performance was fascinatingly observed in salt spray tests even without obvious corrosion phenomenon after 30 days of testing. Due to these remarkable properties, GPP nanocomposites can be an outstanding candidate for the rapid development of broadband shielding and anticorrosive materials.

Preparing high-entropy ceramic films from high-entropy alloy substrate

High-entropy ceramic films with good anti-wear, anti-radiation, anti-corrosion and anti-oxidation performance are attractive for the application in extreme environments such as high temperature, high strength and strong radiation. This paper reported an alternative way to produce high-entropy ceramic films by in-situ nitridation or oxidation of high-entropy alloy substrates. Nitride and oxide high-entropy ceramic films of (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)N and (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)O2 were prepared by heat treatment of high-entropy alloy (Ti0.2Zr0.2V0.2Nb0.2Ta0.2) in 0.1 MPa N2 and air atmosphere, respectively. For the high-entropy ceramic films, except for a small amount of oxides impurity, the solid solutions (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)N and (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)O2 with a simple face-centered cubic and tetragonal crystal structure were the major products and showed homogeneous element distribution. The porous (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)O2 film about 5.5 μm thick has a hardness of 19.8 GPa, modulus of 378 GPa and critical load value of 55.3 mN. And (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)N film about 850 nm thick is relatively dense and exhibits a hardness of 36.7 GPa, modulus of 635 GPa and critical load value of 90.8 mN.

Synthesis of eco-friendly cobalt doped willemite blue pigment from white sand for multi-applications in coatings and inks

PurposeThis study aims to investigate the possibility of synthesizing cobalt doped willemite ceramic blue pigment by using Egyptian white sand as environmental and economical raw material for multi-applications in coatings and inks.Design/methodology/approachAfter the synthesis process, the prepared blue pigment was characterized via X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analysis technique. Then the blue pigment was integrated into both coating and ink formulations. The effect of the prepared multifunctional coatings on corrosion resistance and thermal stability was evaluated using different standard tests. Also, the effect of inclusion of blue pigment in flexographic printing ink formulation was done.FindingsThe results showed that the coating containing the cobalt doped willemite blue pigment offered good anticorrosive performance and high thermal stability. Additionally, the presented results revealed that integration of the blue pigment in flexographic printing ink formulation enhanced fineness, gloss, viscosity and color more than the commercial one “FX 430–201.”Originality/valueIn conclusion, relied on the eco-friendly principle which can be regarded as an economic and green strategy, it can be obtained that this new pigment can provide good multifunctions such as corrosion resistance and thermal stability in coatings and good fineness, gloss, viscosity and color in inks which can enable them to be widely applied in different industries.

Research on Interface Modification and Thermal Insulation/Anticorrosive Properties of Vacuum Ceramic Bead Coating

The thermal insulation effect of the coating was closely related to the content of the thermal insulation filler, but too much filler would cause interfacial compatibility problems of various substances in the coating, micro-defects in the coating, and affect the anti–corrosion performance of the coating. Therefore, solving the interface problem was the key to preparing a coating with heat insulation and anticorrosion functions. In this study, organic–inorganic hybrid polymer was used to modify the surface of vacuum ceramic microbeads, and epoxy–silicone resin was used as the film–forming material to prepare a heat-insulating and anticorrosive coating that can withstand 200 °C. The SEM morphology showed that the interface compatibility of the vacuum ceramic beads modified by the organic–inorganic hybrid agent and the film-forming material were improved, the dispersibility was significantly improved, and the beads were tightly arranged; the thermal conductivity of the coating reached 0.1587 W/(m·K), which decreased by 50% after adding 20% ceramic beads, ANSYS finite element simulation showed that the coating has good thermal insulation performance; after the coating underwent a thermal aging test at 200 °C for 600 h, the microstructure was dense, and the low-frequency impedance modulus was still around 109 Ω·cm2. There was no obvious defect in the microstructure after the alternating cold and heat test for 600 h; the low-frequency impedance modulus was still above 108 Ω·cm2, and the low-frequency impedance modulus of the coating was 1010 Ω·cm2 after the 130d immersion test, indicating that the coating had good heat resistance and anti-corrosion performance.

Rational design of PDMS/paraffin infused surface with enhanced corrosion resistance and interface erosion mechanism

Metal corrosion is a headache in marine industry. The existing technologies can hardly provide an effective long-term corrosion protection. Biomimetic slippery lubricant infused porous surface (SLIPS) has been developed as a potential alternative technique to resolve this problem. Herein, a stable triple-layered slippery surface which consist of compact-nickel-underlayer/porous-nickel-midlayer/PDMS/paraffin infused toplayer was designed and developed for corrosion protection. This composite surface exhibited a low sliding angle with good stability and thermal assitant self-healing property. Simultaneously, it demonstrated good anti-corrosion property with an extremly low corrosion current density and a large impedance of 2.301 × 107 Ω·cm−2, the as-prepared sample even can provide efficient corrosion protection for a long-term immersion in NaCl solution. Furthermore, the interface erosion mechanism was studied via the assistance of electrochemical and surface analysis techniques. The results revealed that no corrosion products were generated which further proved the good anti-corrosion performance. We believe that this triple-layered slippery surface can broaden the application of metals in the field of marine and other industries.

Effect of Curing Agent Dosage on Fire Resistance of Waterborne Epoxy Coating

The water-based epoxy fire retardant coating is formed by reaction curing, which not only has good anti-corrosion performance, but also has environmental protection and flame retardant performance, which is suitable for construction machinery painting or steel structure buildings. However, the curing and cross-linking process of water-based epoxy coatings is centered on the curing agent, which gradually diffuses into the epoxy resin particles. The curing agent molecules first contact the surface of the epoxy resin dispersed phase particles and undergo a cross-linking curing reaction. As the reaction progresses, the relative molecular weight and glass transition temperature of the epoxy resin on the particle surface gradually increase, so that the diffusion rate of the curing agent molecules into the particles gradually slows down, which means that the curing reaction inside the epoxy resin dispersed phase particles Less than its surface, resulting in a low internal crosslink density, and ultimately not all epoxy groups have the opportunity to interact with the activating groups of the curing agent. Therefore, this paper studies different proportions of waterborne epoxy emulsion and curing agent. The results show that when m (epoxy emulsion): m (curing agent) = 7:3, the fire resistance and comprehensive performance of the coating are the best.

Effective corrosion and wear protection of slippery liquid-infused porous surface on AZ31 Mg alloy

Magnesium alloys possess many exceptional advantages and attract much interest from researchers. However, the poor corrosion resistance significantly restricts their extensive applications in industry. Herein, a slippery liquid-infused porous surface (SLIPS), with good surface hydrophobicity, anti-corrosion, anti-wear, self-cleaning and self-healing performances, was developed on AZ31 Mg alloy. MgAl-layered double hydroxides (LDHs) with nanoporous structure were first in-situ synthesized on AZ31. Especially, an environmentally friendly corrosion inhibitor of sodium benzoate was intercalated into MgAl-LDHs to improve the corrosion resistance. After low-surface-energy modification and infusion of lubricant, the desired SLIPS with a homogeneous liquid layer was finally formed. The SLIPS showed good repellency to water to provide superior corrosion protection for the underlying AZ31, with the lowest corrosion current density of 1.93 × 10−9 A cm−2 and the largest impedance modulus of 1.18 × 107 Ω cm2. In comparison with the bare AZ31, the SLIPS exhibited enhanced friction-reducing and anti-wear performance because of the lubricating effect of the infused silicone oil and nanosheets of MgAl-LDHs. In addition, the SLIPS performed well in the self-cleaning and self-healing tests, showing potential to be widely used to enlarge the industrial applications of Mg alloys.

Shaking table test of concrete columns hybrid reinforced by steel/FRP bars

Post-earthquake residual deformation can be decreased due to the designable post-yield stiffness of concrete column reinforced by steel bars/fiber reinforced polymer (FRP) bars. Shaking table tests of three concrete columns with similar initial stiffnesses were conducted, where the longitudinal reinforcement included ordinary steel bars, steel-FRP composite bars (SFCBs) and hybrid reinforcement (steel bars and FRP bars, C–H). The measurements included acceleration response and strain development. The test results showed that the absolute and relative peak ground acceleration (PGA) responses of different columns were similar to one another. The residual strain in the anchorage region was not consistent (tension or compression) and was affected by the longitudinal reinforcement type and the amplitude of the input PGA. For ordinary reinforced concrete (RC) columns, the plastic strain of steel bars developed rapidly after the input ground motion PGA reached 100 Gal, and the corresponding residual strain also developed dramatically. For the SFCB column, even after the peak strain reached 15,000 με, the residual strain was still below 500 με. For hybrid column C–H, the residual strain of the FRP bar was similar to that of the SFCB column. Even when the input wave PGA reached 560 Gal with concrete cover spalling and steel bar buckling, no damage was observed on the FRP bars. In general, compared to ordinary RC columns, concrete columns with hybrid steel and FRP bar reinforcement can achieve a smaller residual deformation, while SFCB reinforced columns can be constructed in severe environments due to a good anti-corrosion performance, such as in offshore structures.

Surface and corrosion properties of Type 430 ferritic stainless steel in parsley (Petroselinum Sativum) essential oil-containing sulphuric acid solution

This study examined the corrosion inhibiting properties of parsley (petroselinum sativum) essential oils, for Type 430 ferritic stainless steel in 0.5 molar sulphuric acid solutions. In this study, weight loss, electrochemical and scanning electron microscope techniques were used in gaining a detailed understanding of inhibition effects of parsley (petroselinum sativum) essential oils (PEO) on Type 430 ferritic stainless steel corrosion. The inhibitor studied exhibits good anti-corrosion performance with 98.65% inhibition efficiency. This result could be ascribed to the adsorbed PEO on the surface of the stainless steel, and this was verified by surface visualization using optical and scanning electron microscope techniques while the crystallographic variation of the inhibited sample is studied by x-ray diffraction (XRD). The adsorption of PEO onto stainless steel surface is controlled by Langmuir adsorption isotherms. Optical images of non-inhibited specimens showed a severely corroded surface with a visible macro pit on the stainless steel from sulphuric solutions. The inhibited sample shows improved surface owing to the surface protection effect of PEO molecules. The corrosion inhibition performance of PEO is due to the presence of active constituents which enhanced the film formation over the surface of the metal, thus, mitigating corrosion.

Low-surface-free-energy GO/FSiAC coating with self-healing function for anticorrosion and antifouling applications

Low surface free energy coating can effectively suppress the initial adhesion of fouling organism. However, continuous attack of corrosive medium will inevitably weaken the coating barrier effect. Herein, a novel self-healing coating based on fluorine‑silicon copolymer (FSiAC) and 0.1 wt% graphene oxide (GO) was prepared by free radical copolymerization. The formed GO/FSiAC coating with the surface free energy of 22.6 mJ/m2 effectively suppressed the adhesion of chlorella, and the inhibition rate was 97%. EIS results showed that the impedance of GO/FSiAC coating increased and the coating porosity decreased with immersion time, indicating that the coating had self-healing property. DSC and FTIR measurements revealed that during the immersion process, the coating cross-linking degree increased due to the formation of net-like Si-O-Si structure. The barrier performance of GO and the self-healing capacity contributed to the superior corrosion resistance of the coating. The outstanding antifouling property is dependent on the low surface free energy of the coating and the antibacterial effect of GO. Novel GO/FSiAC coating with excellent antifouling and good self-healing anticorrosion performance has a potential application in marine engineering fields.

Superhydrophobic Coatings with Photothermal Self-Healing Chemical Composition and Microstructure for Efficient Corrosion Protection of Magnesium Alloy.

Self-healing superhydrophobic coatings have a wide potential for practical applications by prolonging their lifespan, but still suffer from some shortcomings, for example, difficulty in repairing microstructure damage, limited self-healing cycles, and more importantly the inability to self-heal while in service. Herein, we present the fabrication of superhydrophobic coatings having photothermal self-healing chemical composition and microstructure for the high performance anticorrosion of Mg alloy. The coatings contain a shape-memory polymer (SMP) primer and an upper superhydrophobic coating composed of fluorinated polysiloxane-modified multiwalled carbon nanotubes (PF-POS@MWCNTs). The coatings have good superhydrophobicity, photothermal effect, and anticorrosion performance. The coatings show excellent self-healing performance in response to chemical and microstructure damage, such as rapid self-healing under 1 sun irradiation in 10 min, complete self-healing after serious damage (e.g., 10 damage and self-healing cycles and complex microstructure damage), and even self-healing under natural sunlight in 4 h. Moreover, the self-healed coatings show good corrosion protection for magnesium alloy in the neutral salt spray test. These are because of the combination of the SMP primer with good shape-memory effect and the PF-POS@MWCNTs coating with good superhydrophobicity, photothermal effect, and embedded PF-POS. The coatings are self-healable under natural sunlight while in service and thus may find applications in diverse fields.

Friction and anti-corrosion characteristics of arc sprayed Al+Zn coatings on steel structures prepared in atmospheric environment

Al coatings and Al–Zn coatings were prepared on the surface of Q345B steel after shot peening using supersonic arc spraying technology to improve anti-slip and anti-corrosion properties. The SEM, XRD and EDAX were used to detect the surface morphology, coating structure and phase composition of the two coatings. The anti-slip coefficient and anti-wear performance of the two coatings were detected by the anti-slip coefficient detector and the MRTR friction and wear tester, respectively. The anti-corrosion characteristics of the two coatings were obtained by the electrochemical corrosion workstation. The experimental results showed that the thickness of both coatings is 100 μm. The substrate and the coating are mechanically bonded. Under the condition of the test parameters, the anti-slip coefficients of Al coating and Al–Zn coating were 0.717 and 0.823, respectively, satisfying the service requirement of the steel structure. The corrosion potential of the Al–Zn coating was −1.136, which exhibits a good anti-corrosion performance. Under the condition of water, the anti-wear characteristics of Al–Zn were relatively ideal. The wear-resistance of Al–Zn coating is better than that of pure Al coating. In conclusion, Al–Zn coating possesses excellent anti-slip, anti-corrosion and anti-wear characteristics and can be used in large steel structure surface modification.

Research on the Anticorrosion Properties of CeO2-GO/EP Nanocomposite Coating in Simulated Sea Water.

Graphene is a two-dimensional sheet of regular hexagonal honeycomb lattice formed by sp2 hybrid orbital bonding, with only one layer thickness of a single atom, which is known as the “super king” of the 21st century. Previous studies have shown that cerium oxide-graphene oxide (CeO2-GO(4:1)) nanocomposites eliminated the agglomeration of graphene to some extent and the CeO2-GO(4:1) epoxy coating could be prepared with good anti-corrosion performance. In this paper, CeO2-GO(4:1) nanocomposites were prepared by the hydrothermal synthesis method, and the three-electrode method was used for electrochemical tests. The state evolution of CeO2-GO(4:1)/EP coating and the synergy between CeO2-GO(4:1)/EP and corrosion inhibitor in simulated seawater solution with different concentrations (20%, 40%, 60%) were analyzed and illustrated by Optical Microscope (OM) characterization, Open Circuit Potential (OCP), Electrochemical alternating current Impedance Spectroscopy (EIS), Mott–Schottky curve and Tafel curve. The results indicated that CeO2-GO(4:1) nanocomposites showed good corrosion resistance in a marine environment. This research lays a solid theoretical foundation for the application of cerium oxide-modified graphene oxide anticorrosive coating in marine engineering.

Surface Morphological and Chemical Features of Anticorrosion ZrO2–TiO2 Coatings: Impact of Zirconium Precursor

Dense, highly textured, hydrophobic ZrO2-TiO2 (1:1) coatings with amorphous structure were prepared using the sol-gel method. Both organic and inorganic zirconium precursor salts were used. The present study dealt with the investigation of their protective ability in a selected model corrosive medium with chloride ions as corrosion activators. The coatings showed good anticorrosion performance during the test, which was demonstrated both by the weight loss method and potentiodynamic polarization curves. The samples were characterized by means of X-ray diffraction (XRD), Atomic Force Microscopy (AFM), contact angle measurements, Infrared spectroscopy (IRS), Scanning Electron Microscopy (SEM), Differential Thermal analysis (DTA-TG) and X-ray photoelectron spectroscopy (XPS). It was established that the extent of influence of some factors, like treatment temperature (Ttr) and type of zirconium precursor, was different. The PD curves of samples treated at 400 °C (A4 and B4, respectively) demonstrated an increased effect of the precursor in comparison to Ttr, since the application of organic Zr salt led to deterioration of the anodic passivation zones. Contrary to this, the coatings obtained from both the organic and inorganic Zr precursor salts with Ttr = 500 °C had similar corrosion efficiency, i.e., the influence of the precursor was minimized. All investigated coatings had no visible corrosion damage. It seems that some complex structural and surface parameters, such as amorphous dense structure, surface smoothness, hydrophobicity and the surface chemical composition (low hydroxyl groups content), were responsible for the increased anticorrosion properties of the composite films.

Mussel-inspired facile fabrication of dense hexagonal boron nitride nanosheet-based coatings for anticorrosion and antifriction applications

Although great progress has been made recently in the research of hexagonal boron nitride (h-BN) nanosheets, their practical applications are limited due to the difficulties of processability. Existing methods to modify h-BN usually suffer from tedious steps and chemical oxidation reaction conditions, which are being phased out owing to human health and environmental concerns. Herein, inspired by the mussel, dopamine is selected to functionalize h-BN (polydopamine-functionalized hexagonal boron nitride [h-BN@PDA]) nanosheets which can improve interfacial compatibility thus enhancing their processability. As expected, dense h-BN@PDA nanosheet-based coatings can be fabricated through a facile environmentally friendly spraying process in the assistance of polyvinyl alcohol (PVA). The as-obtained coatings present excellent thermal stability because of the hydrogen bonds formed between h-BN@PDA and PVA. Additionally, suitable PVA is beneficial for load transfer, thus improving the mechanical properties of the coatings. More importantly, the composite coatings show good anticorrosion and antifriction performance since the h-BN@PDA nanosheets can act as physical barrier to corrosive medium and oxygen, or be stored in the worn surface as lubricant to reduce the friction and strengthen the friction stability. The facile fabrication process combined with the good thermal stability, anticorrosion and antifriction properties makes the h-BN@PDA nanosheet-based coatings promising candidates for practical applications.

Study on the corrosion resistance of sulfonated graphene/aluminum phosphate composites in waterborne polyurethane coatings

Abstract Sulfonated graphene/aluminum phosphate (SG/AlPO4) composites were synthesized by precipitation method, and composites with different mass ratios were added to water-based polyurethane (WPU) resins to prepare coatings. According to tests, composites with the addition of 2 wt% composite coating has good anticorrosion performance, and its protection efficiency is increased by 79.6% compared with pure resin. In the early stage of the corrosion, the SG layer forms the barrier. During the corrosion process, the SG layer was destroyed, the phosphate ions decomposed by the exposed spherical AlPO4 in the corrosive medium and the divalent iron ions on the iron-based surface form a stable precipitation protective layer to achieve the anticorrosion effect. From the EIS test, the coating with 2 wt% composite material has a larger radius of curvature in the Nyquist diagram at different time periods. According to the fitted circuit, it is further confirmed that the precipitation protection layer has a larger resistance value. After soaking for 24 h the resistance value is the largest, which is 1.231 × 104 Ω cm2.