Effect of silicon nitride and graphene nanoplatelets on the properties of aluminum metal matrix composites

This research work aims at investigating the influence of a fixed content of silicon nitride (Si3N4) and varied contents of graphene nanoplatelets (GNPs) on the physical (density, structural, morphological) and mechanical properties (microhardness, nanoindentation) of Al-Si3N4-GNPs composites. The composites were fabricated by a microwave-assisted powder metallurgy route. The Si3N4 concentration was fixed at (5 wt.%) in Al-Si3N4-GNPs composites while the GNPs concentration was varied between (0 wt.%) to (1.5 wt.%) with an increment of (0.5 wt.%). The structural analysis indicates the formation of phase pure materials with high crystallinity. The microstructural analysis confirmed the presence of the Si3N4 and GNPs showing enhanced agglomeration with the increasing amount of GNPs. Moreover, the surface roughness of the synthesized composites increases with an increasing amount of GNPs reaching its maximum value (RMS = 65.32 nm) at 1.5 wt.% of GNPs. The Al-Si3N4-GNPs composites exhibit improved microhardness and promising load-indentation behavior during nanoindentation when compared to pure aluminum (Al). Moreover, Al-Si3N4-GNPs composites demonstrate higher values of compressive yield strength (CYS) and ultimate compressive strength (UCS) when compared to pure Al despite showing a declining trend with an increasing amount of GNPs in the matrix. Finally, a shear mode of fracture is prevalent in Al-Si3N4-GNPs composites under compression loading.Funding: The APC will be funded by Qatar National Library, Qatar.Scopu

Cerium dioxide nanoparticles as smart carriers for self-healing coatings

The utilization of self-healing cerium dioxide nanoparticles (CeO2), modified with organic corrosion inhibitors (dodecylamine (DDA) and n-methylthiourea (NMTU)), in epoxy coating is an efficient strategy for enhancing the protection of the epoxy coating and increasing its lifetime. Fourier transform infrared (FTIR) spectroscopy analysis was used to confirm the loading and presence of inhibitors in the nanoparticles. Thermal gravimetric analysis (TGA) measurement studies revealed the amount of 25% and 29.75% w/w for NMTU and DDA in the nanoparticles, respectively. The pH sensitive and self-release behavior of modified CeO2 nanoparticles is confirmed through UV-vis spectroscopy and Zeta potential. It was observed, through scanning electron microscopy (SEM), that a protective layer had been formed on the defect site separating the steel surface from the external environment and healed the artificially created scratch. This protective film played a vital role in the corrosion inhibition of steel by preventing the aggressiveness of Cl- in the solution. Electrochemical impedance spectroscopy (EIS) measurements exhibited the exceptional corrosion inhibition effciency, reaching 99.8% and 95.7% for the modified coating with DDA and NMTU, respectively, after five days of immersion time.This research was funded by Qatar National Research Fund (a member of the Qatar Foundation), grant number NPRP Grant 11S-1226-170132. Statements made herein are solely the responsibility of the authors

Improving mechanical, thermal and damping properties of niti (Nitinol) reinforced aluminum nanocomposites

In the present study, Ni50Ti50 (NiTi) particle reinforced aluminum nanocomposites were fabricated using microwave sintering and subsequently hot extrusion. The effect of NiTi (0, 0.5, 1.0, and 1.5 vol %) content on the microstructural, mechanical, thermal, and damping properties of the extruded Al-NiTi nanocomposites was studied. Compared to the unreinforced aluminum, hardness, ultimate compression/tensile strength and yield strength increased by 105%, 46%, 45%, and 41% while elongation and coefficient of thermal expansion (CTE) decreased by 49% and 22%, respectively. The fabricated Al-1.5 NiTi nanocomposite exhibited significantly higher damping capacity (3.23 × 10−4) and elastic modulus (78.48 ± 0.008 GPa) when compared to pure Al.Scopu

Study of microstructural and mechanical properties of al/sic/tio2 hybrid nanocomposites developed by microwave sintering

Aluminum hybrid metal matrix nanocomposites (Al/SiC/TiO2) were synthesized through a microwave-assisted powder metallurgy process, and their evolved microstructure and mechanical properties were investigated. The Al/SiC/TiO2 hybrid nanocomposites were prepared by reinforcing aluminum (Al) matrix with a fixed amount of silicon carbide (SiC) nanoparticles (5 wt.%) and varying concentrations of titanium dioxide (TiO2) nanoparticles (3, 6, and 9 wt.%). The morphology results revealeda uniform distribution of SiC and TiO2 reinforcements in the aluminum matrix. An increase in the hardness and compressive strength of the Al/SiC/TiO2 hybrid nanocomposites was noticed with the increasein TiO2 nanoparticles. The Al/SiC/TiO2 hybrid nanocomposites that had an optimum amount of TiO2 nanoparticles (9 wt.%) showcased the best mechanical properties, with maximum increments of approximately 124%, 90%, and 23% of microhardness (83 ± 3 HV), respectively, yield strength (139 ± 8 MPa), and ultimate compression strength (375 ± 6 MPa) as compared to that of pure Al matrix. The Al/SiC/TiO2 hybrid nanocomposites exhibited the shear mode of fracture during their deformation processAcknowledgments: Penchal Reddy Matli is thankful to the CSIR, New Delhi, India, for financial support under CSIR-SRA (Scientist's Pool Scheme-13(9188-A)/2021-Pool).The authors are also grateful to the Central Laboratory Unit (CLU) Qatar University for the SEM/EDX analysis.Scopu

From soil to plant: strengthening carrot defenses against Meloidogyne incognita with vermicompost and arbuscular mycorrhizal fungi biofertilizers

IntroductionSustainable agricultural practices for controlling crop pests are urgently needed to reduce the reliance on chemical pesticides, which have long-term detrimental effects on ecosystems. In this study, we assessed the effectiveness of arbuscular mycorrhizal fungi (AMF) and vermicompost (Vc) supplementation, alone and in combination, in mitigating the negative impacts of Meloidogyne incognita infestation on carrot (Daucus carota L.) growth, development, and physiology.MethodsWe measured different plant growth parameters such as plant height and biomass accumulation, several plant physiological parameters such as the levels of photosynthetic pigments, phenolics, and the activity of defense enzymes such as peroxidases and polyphenol oxidases, and evaluated the severity of Meloidogyne incognita nematode infestation on plants treated or not treated with vermicompost (Vc) and/or arbuscular mycorrhizal fungi (AMF).ResultsOur findings show that M. incognita significantly affects plant growth, biomass accumulation, and photosynthetic pigment and carotenoid content. The incorporation of Vc and AMF into the soil, either individually or in combination, significantly alleviates the negative effects of nematode infestation on carrot plants. This was accompanied by the induction of phenolic compounds and defense enzymes such as peroxidases (+15.65%) and polyphenol oxidases (29.78%), and by a reduction in the severity of nematode infestation on Vc and AMF-treated plants compared to nematode-infested plants. Principal component analysis (PCA) shows significant correlations between various of the studied parameters. In particular, we observed negative correlations between the application of AMF and Vc alone and in combination and disease severity, and positive correlations between plant growth, photosynthetic pigments phenol content, and activity of defense enzymes.DiscussionOur study highlights the relevance of cultural practices and beneficial microorganisms for the sustainable and environmentally friendly management of agricultural pests

Fast and Scalable Synthesis of LiNi0.5Mn1.5O4 Cathode by Sol-Gel-Assisted Microwave Sintering

High-voltage spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for high-energy-density and high-power-density lithium-ion batteries (LIBs). The high cost of the currently available LIBs needs to be addressed urgently for wide application in the transport sector (electric vehicles, buses) and large-scale energy storage systems (ESS). Of significance, herein, novel fast and scalable microwave-assisted synthesis of LNMO is reported, which leads to a production cost cut. X-ray diffraction (XRD) analysis confirms the formation of the desired phase with high crystallinity. Field emission scanning (FE-SEM) and transmission electron microscopy (TEM) analyses indicate that the synthesized phase is of nanometric size (50–150 nm) due to an extremely short sintering time (20 min). The material synthesized at 750 °C shows a higher initial discharge capacity (130 mA h g−1) than that synthesized at 650 °C (115 mA h g−1). The materials heat treated at higher temperatures show better electrochemical performance in terms of initial capacity, rate capability, and improved cycling. The improved electrochemical performance of LNMO at 750 °C is attributed to the formation of a stable crystal structure, low charge transfer resistance at the electrode/electrolyte interface, high electrical conductivity due to the presence of a disorder structure, and improved ionic diffusivity.This publication was made possible by NPRP Grant # NPRP11S-1225-170128 from the Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. The authors would like to acknowledge the technical support from Oak Ridge National Laboratory (ORNL), Oak Ridge, TN, USA, and the Central Laboratory Unit (CLU), Qatar University, Doha, Qatar. The authors also acknowledge Core Labs. at Qatar Environment and Energy Research Institute (QEERI), HBKU, Qatar, for FE?SEM and TEM analysis. Open Access funding provided by the Qatar National Library.Scopu

A mixed iron–manganese based pyrophosphate cathode, Na2Fe0.5Mn0.5P2O7, for rechargeable sodium ion batteries

The development of secondary batteries based on abundant and cheap elements is vital. Among various alternatives to conventional lithium-ion batteries, sodium-ion batteries (SIBs) are promising due to the abundant resources and low cost of sodium. While there are many challenges associated with the SIB system, cathode is an important factor in determining the electrochemical performance of this battery system. Accordingly, ongoing research in the field of SIBs is inclined towards the development of safe, cost effective cathode materials having improved performance. In particular, pyrophosphate cathodes have recently demonstrated decent electrochemical performance and thermal stability. Herein, we report the synthesis, electrochemical properties, and thermal behavior of a novel Na2Fe0.5Mn0.5P2O7 cathode for SIBs. The material was synthesized through a solid state process. The structural analysis reveals that the mixed substitution of manganese and iron has resulted in a triclinic crystal structure (P[1 with combining macron] space group). Galvanostatic charge/discharge measurements indicate that Na2Fe0.5Mn0.5P2O7 is electrochemically active with a reversible capacity of ∼80 mA h g−1 at a C/20 rate with an average redox potential of 3.2 V. (vs. Na/Na+). It is noticed that 84% of initial capacity is preserved over 90 cycles showing promising cyclability. It is also noticed that the rate capability of Na2Fe0.5Mn0.5P2O7 is better than Na2MnP2O7. Ex situ and CV analyses indicate that Na2Fe0.5Mn0.5P2O7 undergoes a single phase reaction rather than a biphasic reaction due to different Na coordination environment and different Na site occupancy when compared to other pyrophosphate materials (Na2FeP2O7 and Na2MnP2O7). Thermogravimetric analysis (25–550 °C) confirms good thermal stability of Na2Fe0.5Mn0.5P2O7 with only 2% weight loss. Owing to promising electrochemical properties and decent thermal stability, Na2Fe0.5Mn0.5P2O7, can be an attractive cathode for SIBs.Scopu