Smart Anticorrosive Coatings Research Articles

Tribological properties of a smart Ti3C2Tx-based epoxy coating: Providing an idea to solve the weak tribological properties of traditional smart coatings

Friction damage is always a major threat to the wide application of smart anticorrosion coatings. Here, the tribological properties of a smart Ti3C2Tx-based epoxy coating (MLT@EP) is adjusted by the reasonable collocation of mesoporous silica nanocapsules loading onto Ti3C2Tx-based plane (MLT). MLT@EP not only maintains good smart anticorrosion, but also has remarkable anti-friction and anti-wear properties. Its friction coefficient exhibits a low and steady trend, and the wear rate arrived at 1.14 × 10−5 mm3/N·m, which is decreased by 58.3 ∼ 93.3 % compared to control groups. The excellent tribological properties are mainly attributed to the synergistic effect of MXene-based lubrication film, high resistance to plastic deformation, and strong internal interaction.

Development of anti-corrosion coating with sandwich-like microvascular network for realization of self-healing and self-reporting properties based on coaxial electrospinning

Biomimetic microvascular networks prepared by coaxial electrospinning technology have attracted much attention as a novel form of carrier for encapsulating active substances. However, the poor interfacial bonding strength between traditional electrospinning materials and metal substrates limits its application in anti-corrosion coatings. Herein, a novel poly(vinyl alcohol) grafted phytic acid (PVA-PA) electrospinning solution was synthesized. And a sandwich-like microvascular network (SMN) was prepared by coaxial electrospinning technology, which used PVA-PA solution as the shell material, epoxy resin 51 (E51), tetraphenylethylene (TPE) and polyamide resin as the core materials, respectively. Owing to the high porosity of SMN, epoxy resin can be directly spin-coated on it to form a composite coating (PVA-PA/SMN/EP). It is proved that due to the strong chelation and coordination interaction between PA and mild steel, the pull-out adhesion of the PVA-PA/SMN/EP composite coatings on mild steel was increased by 0.92 MPa. In addition, by systematically optimizing the relative viscosity, miscibility, conductivity, and saturated vapor pressure between the two jets of the core solution and the shell solution in coaxial electrospinning, the microvascular structure of the coaxial electrospinning nanofibers was improved and the fluidity of the internal active substances was maintained. When the PVA-PA/SMN/EP composite coating generates microcracks, the active substances encapsulated in the SMN flow out, in which the three-dimensional crosslinked network formed by the curing of E51 and polyamide resin enhances the spatial interactions between TPE molecules, which results in TPE emitting a bright blue fluorescence. This work provides a new approach for the development of the next generation of smart anti-corrosion coatings.

Screening of vegetable drying oils as potential self‐healing agents for smart anticorrosive coatings

Screening of vegetable drying oils as potential self‐healing agents for smart anticorrosive coatings

The multiple faces of graphene on anticorrosion: Advances and prospects

In recent years, graphene has remarkably enhanced the protective performance of anticorrosive organic coatings, yielding increasingly frequent exciting results and perspectives. This paper reviews the latest research advancements that we have gathered on the influences of conductivity, modification, dispersion methods and controllable orientation of graphene; the graphene-based smart anticorrosive coatings; the current understandings on the designs of the anticorrosive coating and the action mechanisms of graphene in the coating. It is concluded that there would be greater opportunities for the gravitational field-induced method to play the shielding effect of graphene; noncovalent modification methods may not ensure satisfactory attachment of the modifiers to the surface; green modification methods are expected to reduce the electrical conductivity of graphene and covalently modify graphene; the self-healing and early-warning graphene-based anticorrosive coatings are becoming a trend in the development of anti-corrosive coatings. The current-faced challenges and the future development prospects of the graphene-based anticorrosive coating were also proposed. Although graphene performs well in anticorrosive coatings, there is still considerable room to improve the performance, and a new round of industrial optimisation and upgrading in the anti-corrosion coating industry is inevitable with the rapid development of the anticorrosive graphene-based filler.

Preparation and characterization of hollow ceria based smart anti-corrosive coatings on copper

Hollow CeO2 nanoparticles were prepared and employed as nano-carriers to encapsule benzotriazole inhibitor. The benzotriazole loaded formulations were co-electrodeposited with silanol groups to fabricate a superhydrophobic self-healing silane nanocomposite on copper. The CeO2 nano-containers had a high loading amount of 21.7%. The release of BTA inhibitor in CeO2@BTA composite was pH responsive. Potentiodynamic polarization tests and electrochemical impedance spectroscopy were conducted to evaluate the corrosion protection and self-repairing ability of the deposited CeO2@BTA-silane nanocomposite in 1 M NaCl solution. Potentiodynamic polarization curves suggested that the CeO2@BTA-silane coated sample exhibited a noble corrosion potential and decreased corrosion current density in comparison with the uncoated specimen. The inhibition efficiency was found to be 99.7%. After 20 d immersion, the impedance modulus at 0.01 Hz decreased slightly to 557.2 kΩ.cm2 from 582.3 kΩ.cm2, revealing an outstanding chemical stability. Most of the artificial defects were sealed and repaired by the formed CeO2 passive coating and Cu-BTA complex. This paradigm offers an efficient strategy for constructing excellent anti-corrosion and self-healing coatings.

Synergistic Effect of Nanoclay and Barium Sulfate Fillers on the Corrosion Resistance of Polyester Powder Coatings

Nanoclay has proven to be an active anti-corrosive additive due to the self-repairing effect from nanoclay swelling and expansion, except for its passive barrier effect due to the high aspect ratio. But it is still uncertain how these effects of nanoclay are intertwined with the other components in a complex coating system in corrosive environments. In this study, we examined the combined effects of nanoclays of two particle sizes with a commonly used cost-reducing filler, BaSO4. By employing neutral salt spray tests, electrochemical analysis, and surface characterization, we identified the optimal conditions for achieving a strong barrier effect. Surprisingly, a relatively low nanoclay dosage of 2% combined with BaSO4 filler exhibited synergistic behavior. Nanoclay not only compensated for the reduction in the barrier effect owing to the addition of BaSO4 by offering self-repairing and barrier effects, but also overcame the delamination issues observed at higher nanoclay dosages (4% and above). The coating panel with 2% larger nanoclay and BaSO4 showed two orders of magnitude higher pore resistance than the coating without nanoclay, remaining at 107 Ω∙cm2 after 25 days of immersion. As a result, this coating panel demonstrated significantly slower corrosion expansion and reached a lifetime of 2500 h when creepage exceeded 2 mm in salt spray tests. This study contributes to a full understanding and proper utilization of nanoclay for high-performance, smart anti-corrosive coatings.

Graphene oxide–polyamine preprogrammable nanoreactors with sensing capability for corrosion protection of materials

Corrosion is one of the major issues for sustainable manufacturing globally. The annual global cost of corrosion is US$2.5 trillion (approximately 3.4% of the world's GDP). The traditional ways of corrosion protection (such as barriers or inhibiting) are either not very effective (in the case of barrier protection) or excessively expensive (inhibiting). Here, we demonstrate a concept of nanoreactors, which are able to controllably release or adsorb protons or hydroxides directly on corrosion sites, hence, selectively regulating the corrosion reactions. A single nanoreactor comprises a nanocompartment wrapped around by a pH-sensing membrane represented, respectively, by a halloysite nanotube and a graphene oxide/polyamine envelope. A nanoreactor response is determined by the change of a signaling pH on a given corrosion site. The nanoreactors are self-assembled and suitable for mass-line production. The concept creates sustainable technology for developing smart anticorrosion coatings, which are nontoxic, selective, and inexpensive.

Manufacturing of a Smart Coating by Using SiO2 Nanoparticles and Hexamine

Recent years have seen a significant increase in interest in smart anticorrosion coatings, which can detect corrosive situations and autonomously discharge corrosion inhibitors. The mild steel surface was coated with pH-sensitive nanocontainers that had been manufactured and doped into an epoxy coating. Elemental mapping, thermogravimetric analysis/differential scanning calorimetry, and electrochemical impedance spectroscopy (EIS) methods were used to examine dispersion homogeneity, thermal durability, and corrosion tolerance. The findings indicated that nanocontainers dispersed uniformly in epoxy and that doping nanocontainers had no effect on the epoxy properties. When immersed in NaCl solution with nanocontainer doping concentrations of 3%, 6%, and 9%, EIS findings showed a rise in epoxy corrosion resistance following 5 d, 10 d, 15 d, 25 d, and 30 d. This enhancement was attributable to the smart release of corrosion inhibitors to protect steel surfaces. Infrared thermography and corroded substrate images confirmed the EIS data. The Korsmeyer-Peppas kinetic model was the best model for fitting the obtained data.

The Thermal Behavior of Two Magnetic States in Smart Anticorrosion Coatings

The Thermal Behavior of Two Magnetic States in Smart Anticorrosion Coatings

The Thermal Behavior of Two Magnetic States in Smart Anticorrosion Coatings

Compounds of nitrilotrimethylenephosphonic acid (NTP) with transition metals are often used as corrosion inhibitors for steels. An FeNTP anticorrosion coating is formed on the steel surface. Doping with certain metals (for example, Zn or Cd) greatly improves anticorrosion properties. Despite the fact that FeNTP, FeZnNTP, and FeCdNTP are completely isostructural compounds, substantial changes in their properties occur upon doping: (i) according to the X-ray electron spectra, Fe atoms in FeNTP are in a high-spin (HS) state, while FeZnNTP and FeCdNTP contain Fe atoms with zero spin (LS); (ii) the difference in the quadrupole splitting of the Mössbauer spectra is specific to the ratio between the HS and LS states. Quan-tum mechanical calculations of the FeNTP system showed two solutions with the properties coincideing with the experimentally found LS and HS states for these systems. In this study, we tested the hypothesis about the coexistence of two states. To study possible thermal redistribution between two magnetic states, the Möss-bauer spectra of FeNTP, FeZnNTP, and FeCdNTP were recorded at various temperatures (77, 300, and 373 K). The Mössbauer data indicate that, with an increase in the temperature, a second component occurs in FeNTP (the ground state is HS; LS occurs already at room temperature and its fraction increases with an increase in the temperature) and FeZnNTP (the ground state is LS; HS occurs at 373 K). At all investigated temperatures, FeCdNTP has only one LS component.

Smart Anticorrosion Coatings Based on Poly(phenylene methylene): An Assessment of the Intrinsic Self-Healing Behavior of the Copolymer.

Poly(phenylene methylene) (PPM) is a multifunctional polymer featuring hydrophobicity, high thermal stability, fluorescence and thermoplastic processability. Accordingly, smart corrosion resistant PPM-based coatings (blend and copolymer) were prepared and applied by hot pressing on aluminum alloy AA2024. The corrosion protection properties of the coatings and their dependence on coating thickness were evaluated for both strategies employed. The accelerated cyclic electrochemical technique (ACET), based on a combination of electrochemical impedance spectroscopy (EIS), cathodic polarizations and relaxation steps, was used as the main investigating technique. At the coating thickness of about 50 µm, both blend and copolymer PPM showed effective corrosion protection, as reflected by |Z|0.01Hz of about 108 Ω cm2 over all the ACET cycles. In contrast, when the coating thickness was reduced to 30 µm, PPM copolymer showed neatly better corrosion resistance than blended PPM, maintaining |Z|0.01Hz above 108 Ω cm2 with respect to values below 106 Ω cm2 of the latter. Furthermore, the analysis of many electrochemical key features, in combination with the optical investigation of the coating surface under 254 nm UV light, confirms the intrinsic self-healing ability of the coatings made by PPM copolymer, contrary to the reference specimen (i.e., blend PPM).

High barrier and durable self-healing composite coating: Boron nitride combined with cyclodextrin for enhancing the corrosion protection properties of waterborne epoxy coating

In recent years, a great deal of research has been devoted to designing smart anti-corrosion coatings with diverse self-healing capabilities, effective passive barrier properties, and long-lasting protection. Herein, the tetraethyl orthosilicate (TEOS) was used as a pH response guardian encapsulated on a BTA-loaded β-cyclodextrin (β-CD) nanocavity shells (CD(BTA)@TEOS), which would be ineffective in acidic environments, thus causing the release of BTA. Meanwhile, the polydopamine (PDA) was coated on the hexagonal boron nitride (h-BN) nanosheets (h-BN@PDA) to enhance its dispersibility and provide reactive sites. Further, the h-BN@PDA-CD(BTA)@TEOS (BPCT) hybrids were synthesized by linking CD(BTA)@TEOS nanocavity shells and h-BN@PDA nanosheets through PDA and KH560 as bridging agents. The dispersion of BPCT in waterborne epoxy coating (WEC) can effectively fill the coating defects and prolong the diffusion path of corrosive media, showing excellent barrier properties due to the excellent barrier properties of h-BN@PDA nanosheets against corrosive media. Meanwhile, the excellent self-healing properties of the composite coating under corrosive conditions were mainly derived from the released BTA and stripped PDA in response to pH variation. The corrosion resistance of the composite coating was tested by electrochemical, salt spray tests and microscopic corrosion morphology, and the self-healing properties of the coating were demonstrated by scratch electrochemistry. The expiration time of the BPCT/WEC sample was extended by 15 d, the persistence time in the salt spray test increased by 100 h, and the self-healing properties appeared after 4 h of coating rupture compared to the control WEC. The results proved that the WEC loaded with BPCT nanocontainers had a high barrier effect along with self-healing function and durable corrosion resistance.

Modification and corrosion resistance of halloysite carrier with metal nanoinhibitor in marine corrosion environment

PurposeThe purpose of this paper is to provide theoretical guidance and an experimental basis for a smart anti-corrosion coating of halloysite nanocontainers loaded with benzotriazole (BTA) inhibitors on copper in a marine corrosion environment.Design/methodology/approachIn the present study, the smart anti-corrosion coatings of halloysite nanocontainers loaded inhibitors on copper were synthesized by adding BTA inside the halloysite nanocontainers. Then, the halloysite carrier’s surface topography and composition in the halloysite were observed using scanning electron microscopy. After the successful synthesis of the coating, the inhibitor’s physical and chemical properties, as well as the mass change in halloysite, were evaluated in terms of temperature fluctuation and time using thermal gravity analysis (TGA). Finally, electrochemical impedance spectroscopy was used to check the pH selectivity for the self-releasing of BTA out of the nanocontainers.FindingsThe results indicate that the efficiency of the nanotubes was enhanced by calcination at high temperatures. The thermal gravity analysis by TGA shows that halloysite nanoparticles store inhibitors BTA and there are approximately 37.39 Wt.% BTA loaded in each nanocontainer. The release of the preloaded BTA from the halloysite nanocontainers is pH 7 in a 3.5% NaCl solution.Originality/valueThe development of a new environmentally safe coating for corrosion protection of metallic surfaces has attracted great interest in material science over the past few years. At present, halloysite nanotubes (HNTs) have become a research hotspot internationally and are widely used in nanocomposites, catalysis, nanofiltration, drug sustained-release and other fields. However, the application of HNT is limited by its modification methods. As the carrier of metal nanocorrosion inhibitor in the Marine corrosive environment, the modification research of HNT still needs to be further studied and improved so as to expand the practical application of HNT in the Marine corrosive environment. In this paper, the modification of HNTs was investigated and observed. Four different modification schemes were used to observe and compare the structural properties of the nanotubes under different conditions so as to provide a theoretical basis for the further loading of HNTs as corrosion inhibitors.

Smart self-healing coating based on the highly dispersed silica/carbon nanotube nanomaterial for corrosion protection of steel

The poor dispersion of carbon nanotubes (CNTs) limits their practical enhancement in polymer matrix due to strong Van der Waals force among them and their high aspect ratio. Here, a highly dispersed silica/carbon nanotube (HAC) nanomaterial was prepared, which effectively solved the agglomeration problem of CNTs-based materials. More importantly, X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TG) and UV–vis spectra results confirm that HAC nanomaterials can achieve the loading and release of corrosion inhibitors. Basing on these, we developed a smart self-healing coating system (HACB/EP) to further improve the corrosion resistance of the coating. Electrochemical impedance spectroscopy (EIS) investigation shows that HACB/EP still has the highest low-frequency impedance value compared with other coatings after 30 d of immersion, and the electrochemical self-healing efficiency (ηes) of HACB/EP with an artificial defect (De-HACB/EP) turns into positive values at the second (24–48 h) and third (48–72 h) stage. In general, the enhanced corrosion protection and excellent self-healing performance of HACB/EP will greatly promote the development of smart anticorrosion coatings.

Electronic structure and chemical bonding in smart anti-corrosion coatings

Nitrilotris-(Methylenephosphonato)-Three-aqua-Iron(II) (FeNTP) is a linear organic-inorganic coordination polymer forming an anti-corrosion coating on the steel surface in aqueous medium with NTP-based corrosion inhibitors. The Cd-containing NTP-based inhibitor has higher protective properties than the inhibitor without cadmium. At the same time, the Fe–O bonds are more covalent, and the data from X-ray photoelectron and Mössbauer spectroscopy allow one to suppose that the Fe atoms within the polymer with Cd are in a different magnetic state. However, the causes of these phenomena and their relationship were not studied before. Here, for the first time, the electronic structure of FeNTP is calculated using density functional theory. A stable solution with a large magnetic moment at Fe atoms (4 μB) is found for FeNTP. The calculated properties correspond to the experimental ones obtained earlier: the Fe magnetic moment (estimated by XPS), the quadrupole splitting (Mössbauer spectroscopy), and the character of the chemical bond between Fe and O atoms (X-ray diffraction). Also, a second, nonmagnetic, solution is found, the calculated properties of which are identical to those of the Cd-containing FeNTP. The difference in electronic structure between these two states manifests itself in different Fe 3d occupancy, angular electron density distribution around the Fe atoms, and magnetic state. The interrelation between the magnetic state of the Fe atoms and their chemical bonds is described. This made it possible to reveal the mechanism for the effect of Cd doping of the protective layers on their anti-corrosive properties. Thus, an approach to developing the more effective and efficient corrosion inhibitors in the neutral aqueous media is proposed.

New valve-free organosilica nanocontainer for active anticorrosion of polymer coatings

Smart coatings with inhibitor loaded nanocontainers exhibit significant efficiency and durability in prolonging metal life-time and reducing catastrophic failure. However, scaling and further practical intelligent anticorrosion applications of such coatings are still greatly limited by time-consuming installation of various nanovalves. Herein, hybrid hollow mesoporous organosilica was obtained by facile selective etching and served as valve-free nanocontainer to prepare smart anticorrosive coatings. Intelligent functions for inhibitor release and coating active corrosion protection are executed by the cargo-framework interaction, which is sufficiently demonstrated by experimental and computational results. Specifically, inhibitor is encapsulated at neutral pH and released under acidic conditions, which can make nanocontainer spontaneously undergo the pH changes resulted from coating damage and corrosion onset, then respond quickly to achieve in situ repair of corrosion. Correspondingly, exposure of the coating sample containing loaded nanocontainer in NaCl solution shows negligible corrosion and exhibits an increase of Rc (from 606.1 kΩ cm2 to 2967 kΩ cm2) and Rct (from 244.1 kΩ cm2 to 1985.5 kΩ cm2) with the immersion time, while significant deterioration of controlled samples (Rct from 118.7 kΩ cm2 to 46.9 kΩ cm2 and from 5.22 kΩ cm2 to 1.93 kΩ cm2, respectively). Notably, this nature-gated approach will provide novel idea for the preparation of smart nano delivery system for smart anticorrosive coatings.

Microcapsule/silica dual-fillers for self-healing, self-reporting and corrosion protection properties of waterborne epoxy coatings

Smart anticorrosive coatings were prepared by adding microcapsules and silica nanoparticles (SNs) in waterborne epoxy matrix and applied on galvanized steel substrates. The microcapsules encapsulated crystal violet lactone (CVL), epoxy monomer and phenyl acetate in methyl methacrylate polymer shell, so that the self-healing and self-reporting functions can be simultaneously realized. SNs can trigger the chromogenic reaction of CVL, while improving the corrosion protection properties of the composite coatings. The comprehensive properties of the coatings were investigated as a function of the weight ratio of CVL/epoxy monomer in microcapsules, the filling content of SNs and microcapsules, as well as the change of pH value. The corrosion current density of the composite coatings decreased with the SNs content and increased with the microcapsule content. Smart coatings with corrosion current density of 2.91 × 10−12 A cm−2 were achieved by adding 15 wt% microcapsules and 15 wt% SNs in epoxy matrix.

Design of a Functional Active Epoxy Coating for Anticorrosion Performance Using SiO2 Nano-Conductive Polyaniline Nanoparticles in Aluminum Blends of Helicopters

In this study, polyaniline (PANI) nanocomposites/silica (SiO2) nanoparticles are used in epoxy to create smart anticorrosive coatings for the alloy used in helicopters. SiO2 was synthesized by a sol–gel method with tetraethyl orthosilicate. Then, PANI/SiO2 nanocomposites were formed by the electrostatic method. Various tests, including Fourier-transform infrared, ultraviolet–visible spectroscopy, x-ray diffraction, thermo-gravimetric analysis and field-emission scanning electron microscopy, have been performed for characterization of the nanocomposites, and the results indicate that the synthesis of these nanocomposites has been completed. Then, 1 wt.% of PANI/SiO2 nanocomposite was added into epoxy resin and cured by polyamine hardener. Epoxy/PANI/SiO2 coatings with 30-µm thickness were tested on the alloy of the helicopter body. The atomic weight fraction of the helicopter alloy was determined by the inductively-coupled plasma emission test. The results indicate that aluminum constitutes 98% of the alloy. Finally, the analysis of the sealed coatings by electrochemical impedance spectroscopy and salt spray tests have demonstrated that epoxy/polyaniline/silica nanocomposites significantly increase the anticorrosive properties of the epoxy.

Epidermis microstructure inspired mica-based coatings for smart corrosion protection

Two-dimensional (2D) graphene-like nanomaterials have gained interest in anticorrosion coatings due to their enable to act as physical barriers to aggressive species, yet 2D coatings are not always effective or sustainable. Inspired by the epidermis microstructure, herein we designed a high-performance anticorrosion coating with rapid self-healing ability via integrating the excellent adhesion property of polydopamine (PDA) and superior barrier properties of natural mica nanosheets (MNSs) for the first time. Such the coating comprises a protective hard top layer with MNSs constituents (“sealing” agents) and a bottom hybrid soft polymer multilayer, forming a stratified epidermis microstructure, can realize a complete restoration of coating defects under water owing to their mutual benefit. These MNSs not only can enhance the barrier performance of the coating matrix to retard the diffusion of aggressive species and hamper polymer release into water, but also induce an anisotropic diffusion to promote the self-healing of the polymer chains. The microstructures of the bioinspired coatings were systemically investigated by scanning electron microscopy (SEM) and optical microscopy (OM) measurements. Electrochemical results confirmed the anticorrosion performance of the coatings were significantly improved. This work provides a new insight for the design and fabrication of 2D nanomaterials reinforced high-performance and smart anticorrosion coatings.

Mesoporous silica nanoparticles as carriers of active agents for smart anticorrosive organic coatings: a critical review.

Mesoporous silica nanoparticles (MSN) have attracted increasing interest for their applicability as smart nanocarriers of corrosion inhibitors, due to their porous structure, resistance to main corrosive environments and good compatibility with polymer coatings. In this review, the main synthetic routes to obtain MSN with tailored textural properties, the design of different loading and stimuli-induced release strategies, the development of advanced organic nanocomposite coatings with MSN and the validation of their anticorrosive performances are reviewed and compared. Through a critical analysis of the literature, the most promising research trends and perspectives to exploit the highly interesting properties of MSN in advanced organic coatings are proposed.