Development of Metal Matrix Composites Using Microwave Sintering Technique

In this book chapter, aluminum (Al)-based metal matrix composites (AMMCs) with various reinforcing ceramic particles, such as SiC, Si3N4, and Al2O3, were produced by microwave sintering and subsequent hot extrusion processes. The role of various nano/micro-sized reinforcements in altering the structural, mechanical, and thermal properties of the microwave-extruded composites was systematically studied. The X-ray diffraction (XRD) patterns indicated that the main components were Al, SiC, Si3N4, and Al2O3 for the studied Al-SiC, Al-Si3N4, and Al-Al2O3 composites, respectively. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) elemental mapping confirm the homogeneous distribution of reinforcing particles in the Al matrix. Mechanistic studies revealed that the Al-Si3N4 metal matrix composite exhibited superior hardness, ultimate compression/tensile strength, and Young’s modulus, while having a lower coefficient of thermal expansion compared to other studied Al composites. Findings presented are expected to pave the way to design, develop, and synthesize other aluminum-based metal matrix composites for automotive and industrial applications

Recent Progress in WS2 -Based Nanomaterials Employed for Photocatalytic Water Treatment

Water pollution is one of the most serious environmental issues globally due to its harmful consequences on the ecosystem and public health. Various technologies have been developed for water treatment such as photocatalysis, which has recently drawn scientists’ attention. Photocatalytic techniques using semiconductors have shown an efficient removal of various water contaminants during water treatment as well as cost effectivity and low energy consumption. Tungsten disulfide (WS2) is among the promising Transition Metal Dichalcogenides (TMDs) photocatalysts, as it has an exceptional nanostructure and special properties including high surface area and high carrier mobility. It is usually synthesized via hydrothermal technique, chemical vapor deposition (CVD), and liquid-phase exfoliation (LPE) to obtain a wide variety of nanostructures such as nanosheets and nanorods. Most common examples of water pollutants that can be removed efficiently by WS2-based nanomaterials through semiconductor photocatalytic techniques are organic contaminants, pharmaceuticals, heavy metals, and infectious microorganisms. This review summarizes the most recent work on employing WS2-based nanomaterials for different photocatalytic water treatment processes.Open Access funding provided by Qatar National Library

Application of Li-, Mg-, Ba-, Sr-, Ca-, and Sn-doped ceria for solar-driven thermochemical conversion of carbon dioxide

The redox reactivity of the Li-, Mg-, Ca-, Sr-, Ba-, and Sn-doped ceria (Ce0.9A0.1O2−δ) toward thermochemical CO2 splitting is investigated. Proposed Ce0.9A0.1O2−δ materials are prepared via co-precipitation of the hydroxide technique. The composition, morphology, and the average particle size of the Ce0.9A0.1O2−δ materials are determined by using suitable characterization methods. By utilizing a thermogravimetric analyzer setup, the long-term redox performance of each Ce0.9A0.1O2−δ material is estimated. The results obtained indicate that all the Ce0.9A0.1O2−δ materials are able to produce steady amounts of O2 and CO from cycle 4 to cycle 10. Based on the average nO2 released and nCO produced, the Ce0.899Sn0.102O2.002 and Ce0.895Ca0.099O1.889 are observed to be the top and bottom-most choices. When compared with the CeO2 material, all Ce0.9A0.1O2−δ materials showed elevated levels of O2 release and CO production

The potential of plasma-derived hard carbon for sodium-ion batteries

Sodium-ion batteries (SIB) are receiving wider attention due to sodium abundance and lower cost. The application of hard carbon to SIB electrodes has shown their significant potential to increase rates, capacities, stability, and overall performance. This article describes the significance of hard carbon, its structural models, and mechanisms for SIB applications. Further, this work unveils the potential of plasma methods as a scalable and sustainable manufacturing source of hard carbon to meet its increasing industrial demands for energy storage applications. The working mechanisms of major plasma technologies, the influence of their parameters on carbon structure, and their suitability for SIB applications are described. This work summarises the performance of emerging plasma-driven hard carbon solutions for SIB, including extreme environments, and revolves around the flexibilities offered by plasma methods in a wider spectrum such as multi-materials doping, in-situ multilayer fabrication, and a broad range of formulations and environments to deposit hard carbon-based electrodes for superior SIB performance. It is conceived the challenges around the stable interface, capacity fading, and uplifting SIB capacities and rates at higher voltage are currently being researched, Whereas, the development of real-time monitoring and robust diagnostic tools for SIB are new horizons. This work proposes a data-driven framework for plasma-driven hard carbon to make high-performance energy storage batteries

Improved self-healing performance of polymeric nanocomposites reinforced with talc nanoparticles (TNPs) and urea-formaldehyde microcapsules (UFMCs)

The present work reports the self-healing performance of the epoxy based polymeric nanocomposite coatings containing different concentrations (1 and 3 wt%) of talc nanoparticles (TNPs) modified with sodium nitrate (NaNO3), and a fixed amount (5 wt%) of urea-formaldehyde microcapsules (UFMCs) encapsulated with linseed oil (LO). The polymeric nanocomposites were developed, coated on polished steel substrates, and their structural, thermal, and self-healing characteristics were investigated using various techniques. The successful loading (~wt 10%) of NaNO3 into TNPs, which can be ascribed to the involvement of physio-chemical adsorption mechanism, is validated and proceeds without altering the TNPs parent lamellae structure. The performed tests elucidated that the self-release of the corrosion inhibitor (NaNO3) from TNPs is sensitive to the pH of the solution and immersion time. In addition, the release of the linseed oil (self-healing agent) from UFMCs in response to the external damage was found to be a time-dependent process. The superior self-healing and corrosion inhibition performance of the protective polymeric nanocomposites coatings containing 3 wt% TNPs and UFMCs/LO are proven using the electrochemical impedance spectroscopy (EIS) studies. A careful selection of smart carriers, inhibitor, and self-healing agent compatible with polymeric matrix has enabled to attain decent self-healing and convincing corrosion inhibition efficiency of 99.9% and 99.5%, respectively, for polymeric nanocomposites coatings containing 3 and 1 wt% TNPs, making them attractive for many industrial applications

Using B4C nanoparticles to enhance thermal and mechanical response of aluminum

In this work, Al-B4C nanocomposites were produced by microwave sintering and followed by hot extrusion processes. The influence of ceramic reinforcement (B4C) nanoparticles on the physical, microstructural, mechanical, and thermal characteristics of the extruded Al-B4C nanocomposites was investigated. It was observed that the density decreased and porosity increased with an increase in B4C content in aluminum matrix. The porosity of the composites increased whereas density decreased with increasing B4C content. Electron microscopy analysis reveals the uniform distribution of B4C nanoparticles in the Al matrix. Mechanical characterization results revealed that hardness, elastic modulus, compression, and tensile strengths increased whereas ductility decreases with increasing B4C content. Al-1.0 vol. % B4C nanocomposite exhibited best hardness (135.56 Hv), Young's modulus (88.63 GPa), and compression/tensile strength (524.67/194.41 MPa) among the materials investigated. Further, coefficient of thermal expansion (CTE) of composites gradually decreased with an increase in B4C content.Scopu

Synthesis & Performance Evaluation of Hybrid Cathode Materials for Energy Storage

Research into the development of novel cathode materials for energy storage applications is progressing at a rapid rate to meet the ever-growing demands of modern society. Amongst various options, batteries are playing a vital role to replace conventional energy sources such as fossil fuels with green technologies. Among various battery technologies, lithium-ion batteries (LIBs) have been well explored and have succeeded in being adjusted with find many commercial applications. At the same time, as an alternative to LIBs, Sodium-Ion Batteries (SIBs) are also gaining popularity due to the presence of Sodium (Na) in abundance and its similar electrochemical characteristics with lithium (Li). However, SIBs are suffering from many challenges such as slow ionic movement, instability in different phases, and low energy density, etc. Many strategies in the literature have been proposed to address the aforementioned challenges of SIBs. Among them, the substitution of Na with Li to form hybrid cathode materials has turned out to be quite promising. The present work aims to investigate the effect of Na substitution with Li in a pyrophosphate framework. Towards this direction, Na(2-x) LixFeP2O7 (x=0,0.6) hybrid cathode materials were synthesized, and their structural, thermal, and electrochemical properties were studied. It is noticed that the incorporation of Li in the triclinic structure of Na2FeP2O7 has a significant effect on its thermal and electrochemical performance. This study can be considered as a baseline to develop some other pyrophosphate-based high-performance hybrid cathode materials

Synthesis and performance evaluation of Na(2-x)LixFeP2O7 (x=0, 0.6) hybrid cathodes

This study reports hybrid cathodes formation by cation substitution in which Li+ substitution has been considered for Na+ in the structure of Na(2-x)LixFeP2O7 (x=0, 0.6) to form Na1.4Li0.6FeP2O7 cathodes. Na(2-x)LixFeP2O7 (x=0, 0.6) cathodes were synthesized using the solid-state synthesis technique and characterized by various methods. The structural analysis (XRD, FE-SEM) indicates that the submicron-sized, phase pure, and crystalline materials having irregular morphology have been developed. Moreover, Li+ substitution does not alter the triclinic parent structure of Na2FeP2O7. Thermogravimetric analysis (TGA) shows that Li+ substitution into Na2FeP2O7 improves its thermal stability up to 550 °C with only ∼5 % weight loss. The electrochemical performance of Na2FeP2O7 and Na1.4Li0.6FeP2O7 in both lithium (Li) and sodium (Na) half-cells is investigated using different electrochemical techniques. It is noticed that Na1.4Li0.6FeP2O7 is electrochemically active both in lithium (Li) and sodium (Na) cells with promising cyclability. However, compared with Na2FeP2O7, Na1.4Li0.6FeP2O7 suffers from inferior electrochemical performance, which might be associated with the lattice distortion of Na2FeP2O7 due to Li+ substitution having a lower ionic radius than the Na+. Considering Na2FeP2O7 as a baseline material, a new hybrid Na1.4Li0.6FeP2O7 cathode has been developed, which can be used to synthesize other new cathode materials with improved performance.This publication was made possible by NPRP Grant#NPRP11S-1225-170128 from Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. Ramazan Kahraman and all the contributors would like to acknowledge the financial support of QU internal grant-QUCG-CENG-20/21-2. FE-SEM analysis was accomplished at the Central Laboratory Unit (CLU), Qatar University, Doha, Qatar.Scopu

Self-healing performance of smart polymeric coatings modified with tung oil and linalyl acetate

This work focuses on the synthesis and characterization of polymeric smart self-healing coatings. A comparison of structural, thermal, and self-healing properties of two different polymeric coatings comprising distinct self-healing agents (tung oil and linalyl acetate) is studied to elucidate the role of self-healing agents in corrosion protection. Towards this direction, urea-formaldehyde microcapsules (UFMCs) loaded with tung oil (TMMCs) and linalyl acetate (LMMCs) were synthesized using the in-situ polymerization method. The synthesis of both LMMCs and TMMCs under identical experimental conditions (900 rpm, 55◦C) has resulted in a similar average particle size range (63–125 µm). The polymeric smart self-healing coatings were developed by reinforcing a polymeric matrix separately with a fixed amount of LMMCs (3 wt.% and 5 wt.%), and TMMCs (3 wt.% and 5 wt.%) referred to as LMCOATs and TMCOATs, respectively. The development of smart coatings (LMCOATs and TMCOATs) contributes to achieving decent thermal stability up to 450◦C. Electrochemical impedance spectroscopy (EIS) analysis indicates that the corrosion resistance of smart coatings increases with increasing concentration of the microcapsules (TMMCs, LMMCs) in the epoxy matrix reaching ~1 GΩ. As a comparison, LMCOATs containing 5 wt.% LMMCs demonstrate the best stability in the barrier properties than other developed coatings and can be considered for many potential applications

Influence of graphene wrapped-cerium oxide coating on spherical LiNi0.5Mn1.5O4 particles as cathode in high-voltage lithium-ion batteries

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.This publication was supported by the Qatar National Research Fund's NPRP Grant # NPRP11S-1225-170128 (a member of the Qatar Foundation). This publication also sponsored via an internal grant from Qatar University (QUCG-CENG-20/21-2). Open Access funding provided by the Qatar National Library. The writers are entirely responsible for the statements stated herein. Moreover, the authors would like to express gratitude to the Central Laboratory Unit (CLU) at Qatar University, for conducting microstructural investigations (FE-SEM/EDX and HR-TEM). The authors would also like to thank Jeffin James Abraham for his technical assistance with various electrochemical characterizations.Scopu