Release Of Corrosion Inhibitor Research Articles

Excellent tribological and anti-corrosion performances enabled by novel hollow graphite carbon nanosphere with controlled release of corrosion inhibitor

This study deals with the preparation and analysis of a novel corrosion inhibitor-infused hollow porous graphite carbon nanosphere (GCN@M16) interposed with a corrosion inhibitor devised with a controlled release mechanism (M16), which was synthesized under ultrahigh carbonization temperature of about 2100 °C and via consequent organic corrosion inhibitor loading. A comprehensive analysis of the tribological and anti-corrosion properties of GCN@M16 was conducted pertaining to this nanosphere being employed as a lubricant additive in 500SN base oil. The as-prepared GCN (Graphitized Carbon Nanospheres) tend to be endowed with low friction coefficients attributable to the high graphitization of carbonaceous matter. The M16 loading not only enhances the dispersion level of GCN in 500SN base oil, but also empowers them as corrosion inhibitors by strengthening their corrosion resistance ability. Furthermore, the porous hollow structure of the novel GCN facilitates the effective regulation of the release of M16 loading, resulting in the prolonged service life of friction pairs. Subsequently, the mechanism of friction reduction and the anti-wear properties of GCN@M16 were deduced. GCN@M16 is capable of effectually forming a stable protective film over the contact surface via a complicated tribo-chemical reaction and physical mechanical deposition. Reflecting the synergistic effect produced by GCN and M16, the as-obtained GCN@M16 tends to exhibit excellent tribological performance, including high extreme pressure up to 950N, low friction coefficient of around 0.06, and fine anti-abrasion (94.3% reduction), and anti-corrosion properties. The results derived in this paper could prove highly beneficial and provide fundamental insights about the formation of lubricating films, as well as stimulate the industrial application of similar versatile lubricant additives.

Controlled release of corrosion inhibitors in self-healing epoxy coatings

Controlled release of corrosion inhibitors in self-healing epoxy coatings

Dual-action self-healing protective coatings with photothermal responsive corrosion inhibitor nanocontainers

This work introduces a novel nanocomposite coating with dual-action self-healing corrosion protection activated by the photothermal response of plasmonic titanium nitride nanoparticles (TiN NPs). TiN@mesoporous SiO2 core–shell nanocontainers were developed as reservoirs for benzotriazole (BTA) corrosion inhibitors and incorporated into the shape memory epoxy coating matrix. Under near-infrared (NIR) light irradiation, the thermogenesis effect of TiN could not only promote the release of corrosion inhibitors from nanocontainers into the crevice, but also trigger the shape memory effect of damaged epoxy to merge the coating scratch. As such, the dual-action self-healing mechanisms combining the formation of an inhibitor-based protective layer and the scratch closure efficiently suppressed the corrosion process at the exposed metal surface. Surface characterization and electrochemical measurement results proved that the nanocomposite coating incorporated with 2 wt% of TiN-BTA@SiO2 exhibited the optimal corrosion protection as well as an excellent self-healing performance that can be initiated within 30 s of NIR illumination. This photo-controlled self-healing approach is potentially useful in designing next-generation self-healing coatings with ultrafast response time and high healing efficiency.

PH-Triggered Release of NaNO2 Corrosion Inhibitors from Novel Colophony Microcapsules in Simulated Concrete Pore Solution.

Herein, pH-sensitive microcapsules containing NaNO2 corrosion inhibitors for protection of steel reinforced concrete were synthesized via water-in-oil-in-water (W/O/W) double emulsion using colophony as the wall material. The average microcapsule size was 79.07 μm in diameter and exhibited a high encapsulation efficiency of 83.2%. Study of the release of corrosion inhibitors from microcapsules in deionized water (DI water, pH 6.8), carbonate/bicarbonate buffer solution (CBS, pH 9.1), and simulated concrete pore solution (SCPS, pH 12.6) demonstrates that the microcapsules are sensitive to pH and display higher release in alkaline media. This is the first study of colophony as an encapsulating agent for corrosion inhibitors. Furthermore, the alkaline pH-triggered release shows the suitability of its use in reinforced concrete systems. A wide thermal stability range was also found for the colophony microcapsules up to 100 °C. These high pH environments (CBS and SCPS) present pH values above the pKa of colophony (7.2), thus triggering enhanced inhibitor release by the ionization and deprotonation of colophony shell. The higher release in CBS and SCPS is demonstrated by the increases of the corrosion inhibitor diffusion coefficient by an order of magnitude from 3.30 × 10-17 m2/s in DI water up to 1.66 × 10-16 m2/s for SCPS. The release performance indicates that the proposed approach can be used to encapsulate a variety of inhibitors for the protection of steel reinforcements. After immersion in different pH solutions, the corrosion potentials of a carbon steel substrate with microcapsules containing nitrite were more noble than when immersed without microcapsules and the corrosion current densities showed comparable values to free corrosion inhibitors. The formation of a passive ferric oxide layer was confirmed by electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy.

Responsive Colloidosomes with Triple Function for Anticorrosion.

Strategies for corrosion protection are required to prolong the life span of metallic structures used by the construction, aerospace, and transport industries. Currently, there are no coatings that can provide at the same time information about the corrosion status of the coated metal and protect the metal against corrosive species and mechanical damage. Herein, triple-functional microcarriers with functions of corrosion sensing, self-healing, and corrosion inhibition are produced and embedded in coatings to prolong the lifetime of metals and enhance the anticorrosion performance of coatings. The microcarriers are prepared by creating Pickering droplets loaded with a corrosion inhibitor and a healing agent and stabilized by silica nanocapsules containing thymol blue as corrosion sensor. The microcarriers are then embedded in a water-based polymer matrix coated on metal substrates. When the coating or metal is mechanically damaged, the healing agent is released from the droplets to hinder further corrosion of the metal. When the local pH value near the metal surface is changing by the generation of hydroxide ion due to the corrosion process, a change of color is detected as well as a release of corrosion inhibitor, leading to a significant decrease of corrosion rate of the coated metal.

Fabrication of β-cyclodextrin modified halloysite nanocapsules for controlled release of corrosion inhibitors in self-healing epoxy coatings

An effective pH-responsive halloysite with β-cyclodextrin shell was demonstrated to control the release of the inhibitor trapped in the halloysite channel. The effect of solution pH variation on the release behavior of nanocapsules was taken into account. The trapping mechanism by the β-CD molecules was investigated by quantum chemistry calculations. Commercial epoxy coating doped with various concentrations of benzotriazole-loaded containers showed a self-healing effect after 42 h of immersion in 0.5 M NaCl solution of the released benzotriazole. The EIS results confirmed the beneficial effect of the exact concentration of the benzotriazole-loaded container on the barrier properties of the epoxy coating, as distinct from increasing the impedance modulus.

The inhibitory and comparative effects of Zn-Al layered double hydroxide microcontainers intercalated with benzotriazole and nitrite for corrosion protection coatings on AISI 1010 carbon steel

The electrochemical impedance spectroscopy and the open circuit potential techniques were used to analyse coatings with layered double hydroxides intercalated with benzotriazole (BTA), nitrite (NO2), and a combination of the two. These materials were added 5% (m/m) to epoxy resin and applied on carbon steel surface as an anticorrosive system. The analyses were performed during 1000 h of salt spray chamber exposure. Morphology and particle distribution on the coatings were characterized by FEG-SEM. The LDH BTA formed a complex with zinc from the LDH layer and a phase based on ZnO/ZnOH, as shown by XRD analysis. This complex may have impaired the LDH-BTA- corrosion inhibition process, as it formed an undesired phase on Zn-Al layers. The LDH NO2- enhanced corrosion resistance, inducing formation of a passivating layer on the metal surface due to corrosion inhibitor release and chloride ion capture. Keywords: LDH, Zn-Al- NO2-, Zn-Al- BTA-, Corrosion, Electrochemical impedance spectroscopy

Facile preparation of redox-responsive hollow mesoporous silica spheres for the encapsulation and controlled release of corrosion inhibitors

The redox-responsive hollow mesoporous silica sphere (HMSS) as smart nanocontainer demonstrates great potential for active agent storage and controlled release. In the present work, HMSS was firstly prepared by surfactant assisted selective etching method. Then, target corrosion inhibitors, 2-mercaptobenzothiazole (MBT) molecules, were loaded and encapsulated with redox-responsive supramolecular nanovalves, ZnO quantum dots. Results reveal that obtained HMSS exhibits a hierarchical mesoporous structure consisting of hollow cavity and mesoporous shell. Corrosion inhibitors were successfully loaded and capped in HMSS nanocontainers, showing on-demand release behavior under specific environment. Moreover, the release efficiency gradually increased with increasing dosage of the reducing agent. Therefore, the novel smart nanocontainers with redox-responsive characteristics will offer a great promise for the development of new generation nano delivery system for corrosion protection accompanying redox environment change.

Preparation of Ce-MOF@TEOS to enhance the anti-corrosion properties of epoxy coatings

A nano-structured hybrid compound was fabricated with excellent corrosion inhibitor encapsulating capacity and the ability of controlled delivery of benzotriazole (BTA) for simultaneous enhancement of the hydrophobic property and corrosion resistance of epoxy coatings. The Ce-metal organic frameworks (Ce-MOF) were synthesized and served as nanocontainers, tetraethyl orthosilicate (TEOS) was further added to form a film to wrap Ce-metal organic frameworks. The addition of benzotriazole into nanocontainers endowed coating system with excellent anti-corrosion performance. The novelty lies in that the tetraethyl orthosilicate membrane would break and produce pores to release benzotriazole uniformly under acid condition, which was a pH-controlled self-healing process through polymer coatings providing an effective release of corrosion inhibitor. The fabricated hybrid compounds were comprehensively characterized with Fourier Transform infrared spectroscopy (FTIR), Ultraviolet–visible spectroscopy (UV-vis), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Electrochemical Impedance Spectroscopy (EIS) was performed to characterize the corrosion behavior of various composite coatings. Results indicated that the 3 wt.%Ce-metal organic frameworks incorporated into the epoxy coatings showed the most excellent anti-corrosion property.

Operating principle of volatile corrosion inhibitors in the jar test

An appropriate corrosion protection is required for transport and storage of high-quality goods and semi-finished parts made from metals. The application of volatile corrosion inhibitors (VCI) as a means of temporary corrosion protection is based on the release of corrosion inhibitors from films, papers, diffusers or oils to the gaseous phase. By adsorption on the metal surface, the inhibitors prevent the degradation of the primary oxide layer and hence impede corrosion. In principle, the anticorrosive effect is independent of the part geometry, because the protected surfaces do not need direct contact with the VCI material. Also, the VCI method does not require costly cleaning of parts prior to further use after transport and storage. The EXCOR jar test is a common method to examine the efficiency of VCI. A metallic sample and a VCI material are exposed in a jar. After conditioning in dry and humid atmosphere, corrosive stress is applied to the sample. To clarify the VCI’s mechanism of action, the test steps, their duration and the type of inhibitors were varied. Thus, the operating principle of VCI during the test was identified. The acquired knowledge enables to understand and tailor the corrosion protection by VCI in service.

Graphene oxide encapsulated by mesoporous silica for intelligent anticorrosive coating: studies on release models and self-healing ability.

Conductive graphene accelerates localized corrosion at exposed coating-metal interfaces as a cathode, which impedes its applications in metal protection. Nevertheless, graphene-polymer coatings are still the best option due to the original impermeability and chemical stability once the galvanic coupling is cut. However, it is difficult to guarantee the miscibility when graphene is employed as the nanofiller. Herein, a bi-layered nanocomposite coating with self-healing capability at the functional level that ensures strong interfacial interaction is reported in this work. Unlike previous nanofiller coatings, the coating with the benzotriazole-loaded nanoreservoir intermediate layer structure and poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate) topcoat was fabricated via the dip-coating and spin-coating technique, respectively. An efficient nanoreservoir with a thickness of 35 nm for corrosion inhibitor delivery was synthesized by a combination of the oil-water stratification method and vacuum loading. Semiempirical models, which have scarcely been reported on corrosion inhibitor release, were blazed to predict the diffusion mechanism. The corrosion resistance was evaluated by electrochemical characterization. With a nanoreservoir loading of 0.25 g/(20 mL ethanol), the bilayer nanocomposite coating not only improved the barrier properties, but also showed self-healing ability for long-term protection. This strategy provides a candidate for the development of graphene-based anticorrosion coatings.

Tannic complexes coated nanocontainers for controlled release of corrosion inhibitors in self-healing coatings

Nanocontainers with controlled release properties have been used in self-healing coatings for many years. However, the spontaneous leakage of the small molecular weight inhibitors from the nanocontainers promoted the development of nanovalves or gatekeepers to control inhibitor release. Herein, we demonstrate a facile method to encapsulate corrosion inhibitor in mesoporous silica nanoparticles (MSNs) with the help of tannic acid complexes, which endow the inhibitor loaded MSNs with pH-controlled release function. Commercial water-borne alkyd coating impregnated with 2 wt% of benzotriazole-loaded nanocontainers presented significant self-healing effect after 20 days of immersion in 0.1 M NaCl solution from both released benzotriazole and tannic acid as confirmed by electrochemical impedance spectroscopy and microscopy. The impedance modulus of coating with nanocontainers increased from 4.7 × 104 Ω cm2 to 1.8 × 105 Ω cm2 after 15 days of immersion.

Corrosion inhibition performance of novel eco-friendly nanoreservoirs as bi-component active system on mild steel in aqueous chloride solution

Abstract An organic/inorganic couple based on halloysite nanotubes (HNT) was employed to provide active corrosion protection on mild steel in 3.5 wt% sodium chloride solution. The HNT impregnated with green aqueous extract of Basil (BNC) was used as active host of corrosion inhibitors. The chemical characterization of BNC was done by field emission-scanning electron microscopy (FE-SEM), Fourier transformation infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). Also, the time-dependent release of corrosion inhibitors was confirmed through ultraviolet-visible spectroscopy (UV–vis). The significant corrosion inhibition efficiency of the active system (about 98%) was proved by electrochemical analyses. The synergistic effect based on formation of chelate between inhibitor molecules and Zn2+ cations, leading to surface film formation, was proposed as the main mechanism for considerable long-term corrosion protection of bi-component system.

A novel composite system composed of zirconia and LDHs film grown on plasma electrolysis coating: Toward a stable smart coating

A novel composite system composed of zirconia and double hydroxide layers (LDHs) was successfully fabricated on the plasma electrolysis (PE) coating. For this aim, the molybdate-loaded LDHs film grown on the PE film of aluminum alloy was modified additionally by zirconia nanoparticles via a facile dip-coating method. The MoO42− anions which were obtained by anion exchange process from the precursor CeMgAl-LDH film, led to decrease the distance between the flakes of LDHs film where a flower-like structure was successfully developed. Moreover, the inclusion of zirconia helped to decrease the size of pores present in the LDHs films. Accordingly, a superior smart protective film was obtained due to the possible synergetic effects between the MoO42− and Ce3+ ions released from LDHs film as well as the high chemical stability of zirconia. The LDHs film modified by zirconia can be regarded as a stable smart coating, meaning that it has the ability to control the release of corrosion inhibitors and providing an excellent long-term electrochemical performance as well.

An Active Corrosion Inhibition Coating of Two Pack Epoxy Polyamide System using Halloysite Nanocontainer

This work deals with encapsulation of corrosion inhibitor in inorganic nanocontainer and the investigation of the corrosion inhibition rate from the nanocontainer. Halloysite nanotubes were used as inorganic nanocontainer for encapsulating the active corrosion inhibitor. These cylindrical shaped halloysite nanotubes are a natural aluminosilicate, which possesses similar chemical composition as that of pure kaolin clay. The structural morphology and functional organic attachments to the halloysite nanocontainers were determined by using TEM and FTIR analysis. It is found that, halloysite nanocontainers are having external and internal lumen is in nanosize (diameter) and length up to several micrometers. A maximum benzotriazole loading up to 10% (by weight) was achieved in inorganic nanotube of 50 nm external diameters and lumen of 15 nm. The release of corrosion inhibitor was carried out for 18 h at different pH ranging from 3 to 10. The weight percent of the benzotriazole encapsulated halloysite nanocontainer was varied from 2 to 10 and then dispersed in 2K clear coat epoxy-polyamide. The self-healing anticorrosion performance of these nanocomposites coating was tested with help of electrochemical impendence spectroscopy (EIS) and Tafel plot. From Tafel plots it is found that the Icorr value decreases to 1.018E–7A/cm2 from 0.018 A/cm2, when coating was applied with 2 wt % nanocontainer.

Ce(III) corrosion inhibitor release from silica and boehmite nanocontainers

Electrochemical impedance spectroscopy clearly appeared as a suitable technique to investigate the releasing properties of cerium (III) loaded on silica and boehmite nanocontainers. In this way the electrochemical behavior of the AA2024-T3 was evaluated by electrochemical impedance spectroscopy in a 0.045 mol L−1 NaCl solution with nanocontainers containing the inhibitor. Results show that the inhibitor release is influenced by both the chemical nature and the morphology of the nanocontainers. The lower loading and release phenomena were observed for the mesoporous silica nanocontainers, whereas the inhibitor is liberated until 168 h from dense silica nanocontainers. Boehmite nanocontainers combine a good loading ratio with a longer release until the second week of immersion.

Corrosion inhibition of carbon steel by hydrotalcites modified with different organic carboxylic acids for organic coatings

Hydrotalcites intercalated with sebacate (HT-SB) were prepared by a coprecipitation method. The synthesized powder was characterized using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta potential measurements. The inhibitor release from HT-SB in a chloride solution has been determined by total organic content (TOC) analysis. The inhibitive action of HT-SB on carbon steel was investigated and compared with hydrotalcites intercalated by benzoate (HT-BZ) and 2-benzothiazolythio-succinic acid (HT-BTSA) using electrochemical measurements and SEM/EDX analysis. The results showed that the zeta potential of modified hydrotalcites and the release of corrosion inhibitors from modified hydrotalcites depend on the chemical structure of inhibitors. The anodic polarization curves showed that the three modified hydrotalcites behave as anodic corrosion inhibitors with an efficiency, at a concentration of 3 g/L, of 94% for HT-SB, 81% for HT-BZ and 92% for HT-BTSA. These efficiencies are higher than those measured for the organic inhibitors in chloride solutions highlighting a synergistic effect due to the combination of the hydrotalcite structure and carboxylate inhibitors. The inhibition effect of modified hydrotalcite depends not only on the intercalated organic inhibitors but also on the capability of adsorption of the hydrotalcite structure on a steel surface. HT-SB was easily dispersed in an epoxy coating improving the barrier properties at concentrations lower than 5 wt.%. The best protection was obtained with 1.5 wt.% HT-SB.

Application of mesoporous silica nanocontainers as an intelligent host of molybdate corrosion inhibitor embedded in the epoxy coated steel

In this study, mesoporous silica served as a host for corrosion inhibitor. This material could adsorb and release corrosion inhibitor in different aqueous media. However, the extent of corrosion inhibitor release in the alkaline media was higher. By dispersing 1wt% mesoporous silica loaded with sodium molybdate in the epoxy layer, a protective composite coating was produced. The corrosion properties of the composite coatings were assessed by electrochemical impedance spectroscopy. Results showed higher corrosion resistance of epoxy/mesoporous silica loaded with inhibitor in the NaCl media for eight weeks of immersion in comparison with epoxy/mesoporous silica. Corrosion inhibitors released from nano-containers in the response to corrosion damage at the interface zone.

Synthesis and characterization of layer-by-layer assembled magnesium zinc molybdate nanocontainer for anticorrosive application

Magnesium zinc molybdate nanoparticles which has been synthesised by conventional method, used as core of nanocontainer. In the present work, a novel approach for the loading and responsive release of corrosion inhibitor (benzotriazole) on the magnesium zinc molybdate nanocontainer by layer by layer (LbL) assembly has been presented. The synthesized nano particle coated with corrosion inhibitor i.e. benzotriazole and polyelectrolyte layer, provides enhanced corrosion protection. The thickness of the layer, surface charge and functional groups present on each layer has been achieved by using particle size distribution (PSD), zeta potential and Fourier transform infrared spectroscopy (FTIR) analysis respectively. The X-ray diffractograms (XRD) and thermogravimetric analysis (TGA) gives the development of nanoparticle as well as nanocontainer. The morphological studies shows the variation in the size of magnesium zinc molybdate nanoparticles and the nanocontainer. The release of benzotriazole from the magnesium zinc molybdate nanocontainer has been quantitatively evaluated in water at different pH. The anticorrosive performance of nanocontainers has been studied by incorporating it in epoxy based coating and evaluating by DC polarization measurement. The current density has been found to be decrease significantly with the addition of 1wt.% of magnesium zinc molybdate nanocontainers in neat epoxy-polyamide resin. Additionally, corrosion potential values are shifted to positive side with the addition of 1wt.% of magnesium zinc molybdate nanocontainers. The corrosion results from Bode plots and Salt spray test shows the significant improvement in anticorrosive performance for epoxy-polyamide-nanocontainer coatings. The results shows the successful application of magnesium zinc molybdate nanoparticles as a core of nanocontainers by giving rise to dual corrosion inhibition mechanism due to combination of magnesium, zinc, molybdate ions and inhibitor loaded on inorganic core.

PH-controlled self-healing polymer coatings with cellulose nanofibers providing an effective release of corrosion inhibitor

Polymer coatings with various pH values and containing cellulose nanofibers and a corrosion inhibitor were applied to carbon steels for corrosion inhibition. The polarization resistance of scratches made to the prepared coatings was measured in a corrosive solution. The resistance of the scratched coatings was largely dependent on the pH of the polymer. The scratched polymer coating prepared at pH 11.4 showed a drastic increase in polarization resistance just after immersion, and was the highest measured after a 24h corrosion test. A corrosion-protective film was formed on the scratched portion.