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.
Durability characteristics of high-performance concrete (HPC) and ultra-high performance concrete (UHPC) are evaluated in comparison to normal strength concrete (NSC). HPC and UHPC are cast using ...commonly available materials with no special heat treatment. Concrete resistivity, rapid chloride permeability, sorptivity, porosity, and resistance to chloride migration and carbonation of these three types of concrete are assessed. Microstructure and hydration products are investigated using scanning electron microscope (SEM) imaging and X-ray diffraction (XRD) analyses, respectively. Potential enhancement in the service life of reinforced concrete (RC) structures when concrete is replaced with HPC and UHPC is predicted using the time-to-corrosion model. Dense microstructures, high electrical resistance, negligible chloride permeability, low sorptivity, no carbonation ingress are observed in HPC and UHPC. The chloride diffusion coefficient was found to be at least three orders of magnitude lower in UHPC compared to NSC, which could delay the corrosion initiation of steel reinforcement. With such positive attributes, these concretes are expected to find more widespread application in concrete structures in harsh-climatic conditions. This paper provides additional data and analysis that could accelerate the adoption of these materials in practice.
•UHPC of 160 MPa could be achieved with common materials without applying heat treatment.•UHPC has three orders of magnitude lower chloride diffusion coefficient compared to NSC.•The carbonation issue could be eliminated with HPC and UHPC.
In recent years, hollow structured nanomaterials owe high attention to research, especially when applied to organic coatings due to their high surface area, loading capacity, and flexible shape and ...structure. Towards this direction, mesoporous hollow carbon nanospheres (MPHS) have been synthesized using the self-assembly method with an average diameter of 280 nm using silica particles as a hard template. The etching of the silica cores was carried out using alkaline etching with NaOH which effectively removed the cores as confirmed by the EDX and FTIR. The MPHS has BET surface area, pore volume, and pore radius of 830.8 m2/g, 1.1 cc/g, and 3.4 nm respectively which support the loading of diethylenetriamine (DETA). The DETA acts as a corrosion inhibitor, surface modifier, and hardener loaded into MPHS with a high loading rate (44 %) to develop MPHS@ DETA. 3 wt% of the MPHS@ DETA was blended with an epoxy coating (MPHS@ DETA-EP) as an anti-corrosion pigment and then the properties of the developed epoxy coatings were systematically characterized. The developed MPHS@ DETA-EP shows excellent anti-corrosion behavior after continuous exposure to corrosive media for 40 days making the coating suitable for several industrial applications.
•The developed coating showed high thermal stability and a large surface area.•Diethylenetriamine showed high loading and surface enhancement to the carbon capsules.•The coating system improved the anti-corrosion properties and provided a prolonged lifetime.
•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.
Cobalt-free LiNi0.5Mn1.5O4 (Lithium Nickel Manganese Oxide; LNMO) has garnered considerable interest as a cathode material due to its high working voltage, lower cost, and environmental ...friendliness. However, LNMO cathodes currently exhibit low cyclability and capacity deterioration, severely restricting their use on a broader scale. To this end, microwave-assisted chemical co-precipitation was used to produce spherical aggregated nanoparticles of LiNi0.5Mn1.5O4 (LNMO) coated with CeO2 (LNMO-Ce) and wrapped in graphene (LNMO-Ce-GO). Structural analysis demonstrates that the ceria coating along with the graphene wrapping prevents unwanted phases from forming and altering the morphology of the LNMO microspheres. LNMO-Ce-GO exhibits a discharge capacity of 132.4 mAhg−1 at the C/10 rate with a capacity retention of 95.3 % after 100 cycles, compared to LNMO-Ce and bare LNMO samples that provide a capacity retention of 91.6 % and 84.7 % respectively. DSC analysis elucidate that the ceria coating helps to suppress the adverse reactions at the electrode/electrolyte interface and reduce the Mn3+ dissolution due to the Jahn Teller effect, increasing cell cyclability. The graphene wrapping reduces material aggregation and provides conductive pathways that significantly improve the electrochemical performance of the LNMO cathode. This innovative material design strategy can be efficiently expanded to other classes of lithium-ion battery cathode materials to enhance their electrochemical performance.
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•Ti3C2-MXene/TiO2 materials have been synthesized employing in-situ hydrolysis of TiO2.•The conformal TiO2 coating on inner and outer surfaces of MXene was achieved.•With high ...electronic conductivity, MXene acts as a host material for TiO2.•Ti3C2-MXene/TiO2 anode resulted in considerable improvement in electrochemical performance.
TiO2 has the potential to be a viable anode material for high-power lithium-ion batteries (LIBs). However, the lower electronic conductivity of TiO2 limits its practical applications. Here, the synthesis of novel TiO2 decorated Ti3C-MXene anode for LIBs using in-situ hydrolysis is discussed. MXenes are well known for their outstanding structural stability and superior electronic conductivities; thus, using MXenes as a host material for TiO2 may improve its structural and electrical characteristics. Scanning and transmission electron microscopy (SEM & TEM) examination revealed that the in-situ method resulted in a uniform and comformal coating of TiO2 (27.5 nm) on the inner and outer surfaces of MXene surfaces. BET analysis revealed that the larger surface area of MXene-TiO2 nanocomposite enhanced the active sites for lithium intercalation, which improved electrochemical performance. Furthermore, electrochemical impedance spectroscopy (EIS) analysis revealed faster kinetics for MXene-TiO2 materials when compared to the TiO2 anode. Compared to pristine TiO2 anode, 5 wt% MXene-TiO2 nanocomposite showed significantly better electrochemical performance, with an electrochemical capacity of around 200 mAhg−1 at 0.1C. Nanocomposites based on MXene-TiO2 exhibit outstanding electrochemical performance, indicating the potential for using MXene-based nanocomposites as an anode in high-performance lithium-ion batteries.
•Bacillus cereus from Qatari soils are capable of producing mineral precipitation in the same quantities as Sporosarcina pasteurii in the urea growth media.•Bacillus cereus was able to fill mortar ...cracks from 162 µm to 670 µm wide, while the Sporosarcina pasteurii filled cracks from 200 µm to 4700 µm width.•Local Bacillus cereus strain showed high urease activity and could be a viable and economical solution for the bio self-healing concrete by the bioprocess of MICP.
In this study, the self-healing process in concrete through microbial-induced calcium carbonate precipitation (MICP) performed by an adapted indigenous strain of Bacillus cereus isolated from soils in Qatar was investigated. This strain has advantage of withstanding and performing MICP in environments of 45–50 °C temperature and 80–100% relative humidity. Hence, it is considered a suitable candidate for self-healing in concrete. The performance of this new isolate was compared to that of Sporosarcina pasteurii, a well-studied strain for MICP in concrete. The strains were encapsulated in sodium alginate beads, which were then incorporated in the cement-sand mortar. It was observed that the selected local strain was able to fill cracks with widths ranging from 162 µm to 670 µm, while the Sporosarcina pasteurii strain was able to fill cracks with widths ranging from 200 µm to 4700 µm. Scanning electron microscopy (SEM) images provided evidence for the survival of the bacterial cells in the beads during the mixing of mortar and casting of the samples. The X-ray diffraction (XRD) spectra and SEM images confirmed the formation of calcium carbonates in the cracks. The local Bacillus cereus strain showed high urease activity and could be a viable and economical solution for the bio self-healing concrete through MICP where hot and humid climatic conditions are encountered.
This paper presents the findings of a systematic comparison of the corrosion behavior of corrosion-resistant steel reinforcements, including epoxy-coated steel, high-chromium steel, and stainless ...steel reinforcement in normal-strength concrete (NC) and highperformance concrete (HPC) columns in an accelerated chloride attack environment for 24 months. The corrosion potential and corrosion rate of the reinforcements were monitored using electrochemical methods, and the degradation of the axial compressive capacity of 40 corroded columns over time was obtained and discussed. Findings indicated that corrosion-resistant reinforcements showed significantly better corrosion performance: no corrosion was observed for intact epoxy-coated and stainless steel reinforcements, and less corrosion (54%) was found on high-chromium steel than conventional mild steel in NC, while similar corrosion rates were found for mild steel and high-chromium steel reinforcements in HPC. Results also indicated that HPC provided reliable protection to the embedded reinforcements, showing smaller corrosion rates than those in NC. The measured average corrosion rate of mild steel and high-chromium steel reinforcements in HPC was 17 to 37% of that in NC. In addition, an analytical model was synthesized to predict the axial load-axial shortening relationship of the corroded circular reinforced concrete columns. Keywords: analytical model; capacity degradation; corrosion; corrosion rate; corrosion-resistant steel reinforcements; high-performance concrete (HPC).
► Wood flour/glass fibre recycled PP composite has good thermomechanical properties. ► Addition of 5wt% GF increases tensile strength by 20% relative to wood flour alone. ► Crystallinity% increases ...with adding the GF. ► Lamellar thickness decreased due to constrained region between lamellae.
Recycled polypropylene (RPP) based hybrid composites of date palm wood flour/glass fibre were prepared by different weight ratios of the two reinforcements. Mixing process was carried out in an extruder and samples were prepared by injection molding machine. Recycled PP properties were improved by reinforcing it by wood flour. The tensile strength and Young’s modulus of wood flour reinforced RPP increased further by adding glass fibre. Glass fibre reinforced composites showed higher hardness than other composites. Morphological studies indicated that glass fiber has good adhesion with recycled PP supporting the improvement of the mechanical properties of hybrid composites with glass fiber addition. Addition of as little 5wt% glass fibre to wood flour reinforced RPP increases the tensile strength by about 18% relative to the wood flour reinforcement alone. An increase in wood particle content in the PP resulted in a decrease in the degree of crystallinity of the polymer. The tensile strength of the composites increased with an increase in the percentage of crystallinity when adding the glass fibre. The improvement in the mechanical properties with the increase in crystallinity percentage (and with the decrease of the lamellar thicknesses) can be attributed to the constrained region between the lamellae because the agglomeration is absent in this case.
This research delves into a hybrid framework involving the synthesis of composite particles combining ceria-modified talc (CeO2@Talc) through a chemical precipitation method. The hybrid particles ...were then loaded with 8-Hydroxyquinoline (8-HQ) to serve as a corrosion inhibitor. The resulting CeO2@Talc-8HQ hybrid particles were subsequently incorporated into a polyurethane (PU) matrix and deposited on steel substrate to investigate and assess their barrier properties. The synthesized particles and developed coatings were characterized in detail utilizing various techniques. The Brunauer–Emmett–Teller (BET) results showed a decrease in the specific surface area and pore volume of modified particles as compared to that of pristine talc. These results demonstrated the successful loading and modification of the particles. The thermal gravimetric analysis (TGA) results showed excellent thermal behavior with only 2 % weight loss beyond 900 °C of the modified CeO2@Talc particles. The potentiodynamic polarization results represented 76.28 % increase in the corrosion inhibition efficiency in the presence of the modified particles. When these modified hybrid particles were reinforced (1.wt%) into the PU matrix, they exhibited an impressive impedance modulus of 56.14 GΩ.cm2 at 0.01 Hz, outperforming blank PU coatings which showed 0.002 GΩ.cm2 after four weeks of immersion in a 3.5 wt% saline solution. The incorporation of modified particles into the PU matrix results in significant improvements in various observed parameters such as the lowest break point frequency, damage index, and intersection frequency of the bode plot. These positive outcomes indicated that the modified coatings efficiently blocked the micropores of the PU matrix, preventing the diffusion of electrolytes into the coatings. Overall, this study not only introduced a novel structural design for superior corrosion mitigation but also demonstrated promising potential of corrosion protection for industrial applications.
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•PU coatings modified with CeO2@Talc-8HQ demonstrated considerably improved corrosion resistance.•Synergistic effect of CeO2 and 8HQ resulted in 99.9 % corrosion inhibition efficiency.•The electrochemical and salt spray test results confirmed the excellent barrier properties of modified PU based coatings.
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