Novel hybrid halloysite nanotubes (HHNTs) were developed and used as smart carriers for corrosion protection of steel. For this purpose, as-received halloysite nanotubes (HNTs) were loaded with a ...corrosion inhibitor, imidazole (IM), by vacuum encapsulation. In the next step, a layer by layer technique was employed to intercalate another inhibitor, dodecylamine (DDA), in the polyelectrolyte multilayers of polyethylenimine and sulfonated polyether ether ketone, leading to the formation of HHNTs. During this process, IM (5 wt %) was successfully encapsulated into the lumen of HNTs, while DDA (0.4 wt %) was effectively intercalated into the polyelectrolyte layers. Later, the HHNTs (3 wt %) were thoroughly dispersed into the epoxy matrix to develop smart hybrid self-healing polymeric coatings designated as hybrid coatings. For a precise evaluation, epoxy coatings containing as-received HNTs (3 wt %) without any loading denoted to as reference coatings and modified coatings containing HNTs loaded with IM-loaded HNTs (3 wt %) were also developed. A comparative analysis elucidates that the hybrid coatings demonstrate decent thermal stability, improved mechanical properties, and promising anticorrosion properties compared to the reference and modified coatings. The calculated corrosion inhibition efficiencies of the modified and hybrid coatings are 92 and 99.8%, respectively, when compared to the reference coatings. Noticeably, the superior anticorrosion properties of hybrid coatings can be attributed to the synergetic effect of both the inhibitors loaded into HHNTs and their efficient release in response to the localized pH change of the corrosive medium. Moreover, IM shows an active release in both acidic and basic media, which makes it suitable for the protection of steel at the early stages of damage, while DDA being efficiently released in the acidic medium may contribute to impeding the corrosion activity at the later stages of deterioration. The tempting properties of hybrid coatings demonstrate the beneficial role of the development of novel HHNTs and their use as smart carriers in the polymeric matrix for corrosion protection of steel.
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In this work, we enhanced the humidity sensing properties of the polyvinylidene fluoride titanium dioxide (PVDF-TiO2) nanocomposites based capacitive humidity sensors by modifying the ...film surface. The surface morphology of the PVDF-TiO2 nanocomposite films was modified using the acetone etching. The structural, morphological, thermal and hydrophilic properties of the nanocomposite films were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and contact angle measurements. To prepare the nanocomposite films, 2.5 wt% solution of PVDF and 0.5 wt% solution of TiO2 was mixed in the volumetric ratio (1:2). To fabricate the humidity sensors, the PVDF-TiO2 nanocomposite films were deposited on interdigitated ITO electrodes by spin coating technique. The humidity sensing properties of the sensors were investigated in the relative humidity (RH) range of 30–80%. The sensor shows a linear and stable response over the whole investigated range. The response and recovery times of the composite based sensors are to be 45 s and 11 s, respectively. The average value obtained for the hystersis is 1.05%.
•Types of various nanocarriers systems.•Functions of nanocarriers for corrosion protection.•Characteristic techniques for nanocarrier based smart coatings.•Applications of smart nanocarriers.•Future ...prospective of nanocarriers.
Steel-made infrastructures have been expanding at an incredible rate worldwide and are critical for the expansion and operation of countless industries. Steel is susceptible to corrosion failures, particularly in aggressive environments, and requires surface protection and effective corrosion management to avoid failures. Corrosion failures are a serious and costly problem. In the Middle East region, the direct costs of corrosion are estimated at around 5% of the gross domestic profit (GDP). The indirect costs are much higher and often unpredictable. Given the economic importance of steel-made infrastructures, its corrosion creates major problems for many industries, namely the oil and gas industry, and is responsible for very high operational expenditures (OPEX). Consequently, the coating industry is under constant pressure, as they need to supply the best coatings to the end-users, ensuring adequate corrosion protection and compliance with the environmental requirements. Corrosion protective coatings are the prime choice for steel protection and are, nowadays, the focus of considerable attention and intense research effort. The reason is that there is an extraordinary increase in environmental consciousness that has been accompanied by new legislation and regulations that concern people's safety, assets sustainability, reliability, and protection of the environment. This scenario poses an enormous challenge to the industry: how to comply with these requirements while keeping competitive solutions and sustainable operations and maintenance costs. Smart multifunctional coatings are providing a viable solution to address the corrosion challenges in a wide range of industries due to their promising self-healing properties. The targeted properties of smart multifunctional coatings are deeply influenced by the type of functionalities, pigments (including smart carriers), inhibitors, self-healing agents, the matrix itself, and the synthesis route. A large variety of anti-corrosion pigments have been designed and used as smart carriers to encapsulate/load various types of inhibitors and/or self-healing agents. In this review, we summarized the recent developments made in the field of pigments used as smart carriers for corrosion protection of steel in numerous industrial applications. Various nanocarriers, also referred to as smart nanocarriers, have been reported comprising of inorganic, organic, and hybrid scaffolds and used as additives in coatings for corrosion protection of different materials. This review also includes various characterization techniques employed to evaluate the self-healing performance of coatings modified with smart carriers. Besides, commendable advances, there is still the need for progress in designing novel smart carriers compatible with different coatings matrices and able to be loaded with various chemical species to enhance the corrosion protection ability and self-healing performance. It is, therefore, essential to review the earliest developments made so far for a better understanding of the existing strategies. A concise overview on this topic will provide a robust scientific background and will serve as a baseline to synthesize future novel smart carriers for developing anti-corrosion coatings with improved self-healing performance. Overall, such systems are expected to serve as facilitators for better corrosion management of coated steel parts.
•Ce0.9M0.1O2−δ materials (where, M = Ni, Zn, Mn, Fe, Cu, Cr, Co, Zr) successfully synthesized.•CeZn and CeFe are better than CeO2 for thermochemical H2O/CO2 splitting cycles.•CeZn and CeFe releases ...an average of 50.5 and 50.0 μmol of O2/g·cycle at 1400 °C.•CO production capacity of CeZn and CeFe material is equal to 103.3 and 96.3 μmol of CO/g·cycle at 1000 °C.
In this paper, the effect of doping of transition metal cations on thermal reduction and CO2 splitting ability of Ce0.9M0.1O2−δ materials (where, M = Ni, Zn, Mn, Fe, Cu, Cr, Co, Zr) is investigated by performing multiple thermochemical cycles using a thermogravimetric analyzer. The Ce0.9M0.1O2−δ materials are successfully derived via co-precipitation method and analyzed via powder X-ray diffraction (PXRD), scanning electron microscope (SEM), and BET surface area analyzer (BET). The Ce0.9M0.1O2−δ materials derived are further tested towards their O2 releasing and CO production capacity by performing ten thermochemical CO2 splitting cycles. The obtained TGA results indicate that CeZn and CeFe are capable of releasing higher amounts of O2 as compared to other Ce0.9M0.1O2−δ materials at 1400 °C. Likewise, these two oxides are again observed to be better than other Ce0.9M0.1O2−δ materials in terms of their CO production capacity at 1000 °C. For instance, CeZn and CeFe releases an average of 50.5 and 50.0 μmol of O2/g·cycle during ten thermochemical cycles in which the thermal reduction step is performed at at 1400 °C. Also, the CO production capacity of CeZn and CeFe material is observed to be equal to 103.3 and 96.3 μmol of CO/g·cycle for ten thermochemical cycles in which the CO2 splitting is carried out at 1000 °C. The compositional and thermal stability of all Ce0.9M0.1O2−δ materials is also analyzed after performing ten thermochemical cycles. The phase composition of all the Ce0.9M0.1O2−δ materials remain unchanged after performing ten thermochemical cycles. However, the crystallite size of all the Ce0.9M0.1O2−δ materials increases after performing the ten thermochemical cycles due to the high temperature processing.
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•Novel cerium tri(bis(2-ethylhexyl)phosphate) corrosion inhibition additive.•High compatibility with epoxy coatings.•Increased corrosion resistance of coated steel panels.•Corrosion ...healing in defects.•Synergistic cathodic and anodic corrosion inhibitors.
In this work cerium tri(bis(2-ethylhexyl)phosphate) (Ce(DEHP)3) particles were used as anti-corrosion pigments in epoxy coatings applied on steel coupons. The composition of the corrosion inhibitor was designed to introduce pH-stimulated corrosion healing in the coating. Electrochemical Impedance measurements demonstrated very high compatibility between the inhibitor and the coating, and effective and stable corrosion protection. Localized electrochemical measurements carried out using the Scanning Vibrating Electrode Technique and Localised Electrochemical Impedance revealed efficient corrosion inhibition of steel exposed in artificially damaged coatings.
Synthesized cellulose microfibers (CMFs) were used as a smart carrier for the loading of inhibitor-dodecylamine (DOC) and inhibitor/self-healing polyethyleneimine (PEI). The loaded CMFs were ...thoroughly dispersed into the polymeric matrix to develop smart self-healing epoxy coatings. Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR), and thermogravimetric analysis (TGA) confirm the successful loading of inhibitors and self-healing agents on CMFs. UV-vis analysis indicates the pH sensitivity and time-dependent release of the loaded inhibitor. The inhibition mechanism and chemical interaction of the protective surface film layer on steel elucidated their role in autonomous self-healing. The electrochemical impedance spectroscopy (EIS) measurements for a scratched coating sample demonstrate the increase in the impedance value for the smart coatings as compared to the reference coatings. This improvement is attributed to the efficient release of corrosion inhibitor and the development of a stable, protective film due to the self-healing effect. The synergetic effect of DOC and PEI revealed the self-healing ability of a smart epoxy coating.
.The cellulose microfibers (CMFs) were synthesized to assist the self-release of loaded product, that provides better corrosion inhibition and self-healing of epoxy coatings.
Smart polymeric composite coatings demonstrating multilevel self-healing characteristics were developed and characterized. The pH-responsive smart carriers were synthesized by loading halloysite ...nanotubes (HNTs) with the benzotriazole corrosion inhibitor (BTA) using the vacuum cycling method, referred to as (BTA-loaded HNTs). Similarly, mechanically triggered melamine urea-formaldehyde microcapsules encapsulated with the boiled linseed oil-self-healing agent (LO) denoted as (MUFMCs) having an average size of a ∼120 μm diameter with a wall thickness of ∼1.84 μm were synthesized by the in situ polymerization technique. The newly designed double-layered smart polymeric composite coatings (DLPCs) were developed by mixing 3 wt % BTA-loaded HNTs with epoxy and applying it on the clean steel substrate to form a primer layer. After its complete curing, a top layer of epoxy containing 5 wt % of MUFMCs was deposited on it. For an exact comparison, single-layer polymeric composite coatings (SLPCs) containing 3 wt % BTA-loaded HNTs were also developed. The Fourier transform infrared radiation spectra of MUFMCs and BTA-loaded HNTs indicate the existence of all desired functional groups, confirming the presence of loaded chemical species such as LO and BTA into the smart carriers. Thermogravimetric analysis (TGA) indicates that ∼18% BTA is successfully loaded into HNTs. Quantitative UV-spectroscopic analysis indicates a pH-responsive release of BTA from BTA-loaded HNTs, which is time-dependent, attaining its maximum value of ∼ 90% in an acidic medium after 30 h. Electrochemical impedance spectroscopy analysis conducted in 3.5 wt % NaCl solution at room temperature for different immersion times reveals that SLPC exhibits the maximum charge-transfer resistance (R ct) of 55.47 GΩ cm2 after the 7th day of immersion, and then, a declining trend is observed, reaching 26.6 GΩ cm2 after the 9th day. However, in the case of DLPC, the R ct values show a continuous increment, attaining a maximum value of 82.11 GΩ cm2 after the 9th day of immersion. The improved performance of DLPC can be ascribed to the efficient triggering of the individual carriers in the isolated matrices, resulting in the release of LO and BTA to form individual protective films at the damaged area due to the oxidative polymerization process and triazoles’ ability of passive film formation on the substrate, respectively. The tempting self-healing properties of DLPCs justify their decent role for long-term corrosion protection in many industrial applications.
In the present study, aluminum based metal matrix composites containing various amounts of boron nitride (BN) nanoparticulates (0, 0.5, 1.0 and 1.5 vol.%) were fabricated by using the powder ...metallurgy (PM) technique involving microwave sintering and hot extrusion process. The microstructure, physical, thermal, mechanical and damping characteristics of the extruded nanocomposites were investigated. Field emission scanning electron microscopy (FE-SEM) study shows the evenly distributed BN particles in Al matrix. Mechanical analysis indicates that the compression, hardness and tensile strength of Al-BN nanocomposites increases with increasing amount of BN content. Particularly, a significant improvement in the tensile strength (∼36%) is achieved in Al-1.5 vol.% BN nanocomposite when compared to the pure aluminum (Al). This improvement strength can be attributed to the dispersion hardening of the Al matrix due to the presence of hard BN nanoparticles. Thermal analysis shows that the coefficient of thermal expansion (CTE) decreases with increasing amount of BN which may be ascribed to inherent low CTE of BN nanoparticles used as reinforcement. The addition of BN nanoparticulates enhanced the damping characteristics of pure Al with Al-1.5 vol.% BN nanocomposite exhibiting the maximum damping capacity and damping loss rate with a minimum change in elastic modulus. The improved combination of properties exhibited by Al-BN nanocomposites make them potential candidates for a wide spectrum of industries especially for weight critical applications.
•Al-BN nanocomposites were firstly synthesized by microwave sintering followed by hot extrusion.•Al-BN nanocomposites exhibited superior hardness, tensile/compressive and damping properties.•Al-BN nanocomposites exhibited better ductility behavior under tensile loading when compared to pure Al.•Al-BN nanocomposites showed superior dimensional stability due to decreasing thermal coefficient values.
Pulse electrodeposition is a technique of particular interest, which offers promising advantages such as ease of processing, compositional control, uniformity in structure, and grain refinement. In ...the present study, NiP-ZrO2 nanocomposite coatings containing various concentrations of ZrO2 nanoparticles (ZONPs) were deposited on low alloy steel (30CrMnSi) through pulse electrodeposition technique. The ZONPs in concentration of 0.0, 0.25, 0.50, 0.75, and 1.0 g/L were added in the electrolyte bath to obtain NiP-ZrO2 nanocomposite coatings. Furthermore, to elucidate the role of ZONPs in the NiP matrix, the structural, morphological, mechanical, and electrochemical properties of NiP-ZrO2 nanocomposite coatings were studied thoroughly. FESEM and EDX results reveal the successful incorporation of ZONPs into the NiP matrix. XRD and XPS analysis confirm the formation of a pure phase NiP structure without any noticeable defects. A considerable improvement in the mechanical response was observed with an increasing amount of ZONPs, reaching to highest values (hardness 6.7 GPa, modulus of elasticity 21.72 GPa) for NiP-1.0 ZrO2 coating composition. Similarly, the electrochemical results show a gradual increase in corrosion protection behavior of the NiP-ZrO2 coatings with increasing ZONP concentration, reaching an eventual value ~5.8 kΩ cm−2 at NiP-1.0 ZrO2 coating composition, which is six times greater than the pure NiP coatings. These improvements in the mechanical and electrochemical response of NiP-ZrO2 nanocomposite coatings highlight their suitability for applications such as oil and gas pipelines.
•NiP-ZrO2 nanocomposite coatings were developed and characterized.•The pulse electrodeposition technique was employed to synthesize coatings.•ZrO2 nanoparticles have a significant influence on the mechanical properties of coatings.
Organic-inorganic halide perovskites have rapidly grown as favorable materials for photovoltaic applications, but accomplishing long-term stability is still a major research problem. This work ...demonstrates a new insight on instability and degradation factors in CH3NH3PbI3 perovskite solar cells aging with time in open air. X-ray photoelectron spectroscopy (XPS) has been used to investigate the compositional changes caused by device degradation over the period of 1000 hrs. XPS spectra confirm the migration of metallic ions from the bottom electrode (ITO) as a key factor causing the chemical composition change in the perovskite layer besides the diffusion of oxygen. XPS results are in good agreement with the crystallographic marks. Glow discharge optical emission spectrometry (GD-OES) has also been performed on the samples to correlate the XPS results. Based on the experimental results, fundamental features that account for the instability in the perovskite solar cell is discussed.
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