Nanoscale Aluminum Research Articles

Rapid Shape Change and Spallation of Isolated Nanoscale Aluminum Cubes, Rods, Pyramids, and Spheres: Implications for Plasmonic and Energetic Materials

Rapid Shape Change and Spallation of Isolated Nanoscale Aluminum Cubes, Rods, Pyramids, and Spheres: Implications for Plasmonic and Energetic Materials

Exploring the impact of aluminum oxide nanoparticles on waste transformer biodiesel blend under variable injection timing

This study investigated the use of nano-blended biodiesel, made by mixing waste transformer biodiesel with nanoscale aluminum oxide particles. A fuel blend ratio containing both diesel and biodiesel components was created with 100 parts per million of alumina nanoparticles. All tests were conducted at various loads in an engine, using diesel, biodiesel, and nano-blended biodiesel fuel. The outcomes demonstrated that adding nanoparticles improved engine thermal efficiency and reduced emissions, especially at higher fuel injection timings. The greatest increase in brake thermal efficiency, 6% higher than diesel mode, was achieved with a nano-blended biodiesel formulation containing 100 ppm of aluminum oxide, at a fuel injection timing of 27 before top dead center under full load conditions. With a constant nanoparticle-blended biodiesel content and fuel injection timing of 27 before top dead center, reductions of 1.5% in smoke, 33% in hydrocarbon, and 8% in carbon monoxide emissions were observed, with a 9.7% increase in NO emissions.

NUMERICAL MODELING OF THE INFLUENCE OF NANOPURGE OF ALUMINUM ON BURNING OF HIGH-ENERGY MATERIAL IN A CLOSED VOLUME

A theoretical study of combustion in the manometric bomb of the constant volume of charge, consisting of grains of high-energy material containing nanoscale aluminum powder, is presented. A comparison of an experimentally measured dependence of pressure growth in a manometric bomb with calculations on the thermodynamic model of burning of a hitch of high-energy material in a manometric bomb using an empirical law of the dependence of the rate of combustion on pressure and the conjugated model of nonstationary combustion. A numerical analysis of the effect of the additive of nanoscale aluminum powder in the composition of the high-energy material on the dynamics of burning charge in a pressure gauge bomb.

In situ polymerized polyetherimide/Al2O3 nanocomposites with significantly improved capacitive energy storage performance at high temperatures

High-temperature polymer nanocomposites with high energy storage density (Ue) are promising dielectrics for capacitors used in electric vehicles, aerospace, etc. However, filler agglomeration and interface defects at high filler loadings significantly limit the enhancement of Ue and hamper the large-scale production of the nanocomposites. Here, polyetherimide (PEI) nanocomposites with nanoscale alumina (AO) at ultra-low contents were prepared via in situ polymerization from PEI monomers. We compared two composite dielectric preparation methods (in situ polymerization and ordinary solution blending) under the same conditions. In contrast to the nanocomposites obtained by blending PEI polymers with AO, the in situ nanocomposites exhibit substantially improved filler dispersion, together with largely suppressed conduction loss at high fields and high temperatures, leading to comprehensive enhancements of breakdown strength (Eb), charge-discharge efficiency (η) and Ue, simultaneously. The 0.3% (in volume) AO filled PEI nanocomposite film exhibits a superior Ue of 4.8 J/cm3 with η of 90% at 150 °C, which is 128% and 218% higher than those of pristine PEI and the ex situ PEI/AO nanocomposite film under the same conditions, respectively. This work provides a scalable strategy for the preparation of dielectrics with both good processability and excellent high-temperature energy storage performance.

Comparative Analysis of Microscale and Nanoscale Alumina Reinforcement in Al-Cu-Mg-Al2O3 Composites: Impacts on Density, Porosity, and Hardness

Comparative Analysis of Microscale and Nanoscale Alumina Reinforcement in Al-Cu-Mg-Al2O3 Composites: Impacts on Density, Porosity, and Hardness

TWO TYPES OF GALLIUM EXPOSURE TO ALUMINUM

The effect of gallium on aluminum during their fusion is investigated. The corrosion rate of aluminum alloys with 1, 2 and 5 at % gallium content was experimentally determined, which was 0.001, 0.00101 and 0.00062 g/m2 · h, respectively, which is less than that of pure grade A99 aluminum – 0.0016 g/m2 · h. The rate of dissolution of these alloys in acidic and alkaline media is determined. X-ray phase analysis showed the homogeneity of the alloys under consideration. The morphology of aluminum alloys with gallium was studied, after exposure to an aggressive environment – a solution of hydrochloric acid. The possibility of obtaining hydrogen and nanoscale alumina by decomposition of water by activated gallium aluminum alloy is shown. Activation of the aluminum surface by gallium alloy occurs according to the Rebinder effect and the article presents a micrograph of the surface of aluminum treated with Ga-Sn alloy, clearly demonstrating this effect. When using metallic gallium in contact with aluminum, the interaction requires heating to a temperature above 30°C (the melting point of gallium is 29.7°C), the melting point of the eutectic composition 92Ga–8Sn is 20.0°C, which allows the interaction to begin at room temperature. At temperatures of about 4°C, activated aluminum can be stored for a long time. The quality of hydrogen obtained by decomposition of water should be higher than that obtained by cracking, and the cost is close to a well-developed technology of electrolysis of water and no more than 2 times the cost of its synthesis via cracking of hydrocarbons. Gallium and its liquid alloys are non-toxic, almost do not interact with water, activate aluminum, preventing the formation of a protective oxide film, penetrate into the intergranular space and aluminum easily interacts with water, forming hydrogen and aluminum hydroxide.

From a superconductor to a Mott insulator: The case of granular aluminum

Understanding the nature of the metal-to-insulator in films consisting of nano-scale aluminum grains embedded in an insulating matrix, namely granular aluminum, is essential both on the fundamental level and for applications such as quantum circuits. We show how the evolution of the system from the metallic side (and superconducting at low temperatures) to the insulator side, through a Mott transition, involves rich physics such as the Kondo effect, pseudo-gap effects, collective modes, and a BCS–BEC crossover. We focus on samples prepared on a liquid nitrogen-cooled substrate, having a grain size of about 2 nm, and suggest that the role of the grain size and hence quantum size effects are essential to explain some of the observed phenomena.

High performance nAl@CuO core-shell particles with improved combustion efficiency and the effect of interfacial layers on combustion

Nanoscale aluminium (nAl)-based composites find important applications in propellant, explosives and pyrotechnics, and the improved combustion efficiency is always desirable but challenging. A core-shell nAl@CuO composite with improved combustion performance was prepared by means of a biological interfacial layer, which is inspired by the fast polymerization and strong adhesion of juglone and tannic acid in walnut peel juice. It is found that interfacial layer contains phenolic hydroxyl and amino groups, which could interact with nAl and introduce the growth of CuO crystal, respectively. Obtained nAl@CuO shows higher stability but 1.2 times more heat release than that of the mechanically mixed nAl/CuO. In addition, nAl@CuO also has 5 times faster burning rate than the mechanically mixed one. It is believed that interfacial layer hindered the direct contact of reactants but improved mass transport/diffusion efficiency in nAl@CuO. Thus, Al based composites with higher stability and superior combustion efficiency could be obtained by this interfacial layer.

Formation of Polymer Threads with Nanoscale Aluminum Formations

Formation of Polymer Threads with Nanoscale Aluminum Formations

A review on adsorption efficiency of widely adopted adsorbents used in Defluoridation of aqueous media

The review article provides an insight on various adsorbents and their efficiency in fluorideremoval fromdrinking and waste water. The capacity of fluoride removal of adsorbent is dependent on pH, contact time,temperature, surface area of adsorbent and initial concentration of fluoride solution etc. In comparison tothe traditional natural methods, the synthetic and nanostructure-based adsorbents, exhibited higherperformance and efficiency of defluorination which provides a sustainable approach to safe drinking waterquality. The present paper deals with some widely adopted natural adsorbent, synthetic and nanostructurebasedadsorbents. The natural adsorbent includes, thermally treated lateritic soil, modified natural magnetiteore (Fe3O4) with aluminum and lanthanum ions, lateritic soils, Titanium hydroxide, limestone (LS) andaluminium hydroxide, sedimentation with calcium and aluminium. The Synthetic adsorbent includes,Surface-functionalized polyurethane foam (SPUF); Schwertmannite; Carbonaceous material from pyrolysisof sewage sludge; Chitosan. And the effective adsorbent nano scale structure includes, nanoscale aluminiumoxide hydroxide (AlOOH), Magnetic iron oxide/aluminium hydroxide composite, sulfatedoped Fe3O4/Al2O3 nanoparticles, nano-scale aluminum oxide hydroxide (nano-AlOOH), Graphene Nanoparticlesadsorbent, Al2O3/Bio-TiO2 nano composite (ABN), Green synthesized Fe3O4/Al2O3nanoparticles with coatedpolyurethane foams etc. The activated alumina is most conventional fluoride adsorbing material. However,activated alumina performs well in acidic environment with complex regeneration issue. Although othertraditional adsorbents remove fluoride from water but they have lower efficiency, which restrict theirapplication. In case of synthetic and nano structured based adsorbents, due to increased surface area, nontoxicnature, limited solubility in water and high adsorption efficiency, these methods are widely accepted andproven environmentally suitable.

Highly Filled Composite Materials Based on UHMWPE and a Mixture of Micron and Nanoscale Aluminum Particles

Highly Filled Composite Materials Based on UHMWPE and a Mixture of Micron and Nanoscale Aluminum Particles

Fe-Ni-Co Electrodeposited Nanowires Decorated with Au

Alloy nanowires containing Fe, Ni and Co are of interest as electrode materials in miniaturized devices due to their ability to align them under a magnetic field. In order to improve their resistivity while retaining their magnetic behavior, Fe-Ni-Co nanowires were electrodeposited and decorated with Au; single nanowires were then further characterized (Fig. 1). The nanowires were deposition under a constant applied potential within a nanoscale alumina template, followed by dissolution of the membrane, release of the nanowires, and subsequent treatment in a gold acid electrolyte. Au clusters formed on the Fe-Ni-Co surface through simultaneous displacement and corrosion reactions. The morphology, composition and structure was examined before and after modification, revealing a change in crystallinity and composition that impacted the nanowire’s electrical and magnetic properties. Transferring a single nanowire to a lithographically prepared two-point probe enabled the electrical and magnetic characterization of the Au decorated nanowire. Averaging results of quadruplicate replicates, a low coverage of discontinuous Au clusters on Fe-Ni-Co nanowires significantly decreased the resistivity, not attributed entirely to the lower resistivity of Au, but as a consequence of changes of the Fe-Ni-Co crystallinity. A high coverage of the Fe-Ni-Co by Au had no further benefit, and even increased the resistivity. Since bulk gold is diamagnetic and decoration of Au onto the Fe-Ni-Co nanowires may compromise the overall magnetic property, the magnetoresistance and electron mobility were determined. Both decreased, as expected, with coverage of Au clusters on the nanowires, suggesting that there may be an optimal cluster density for modifying the Fe-Ni-Co nanowires. Figure 1. Electrodeposited nanowires initially amorphous then decorated with Au showing a change in crystallinity and subsequent characterization with a two-point probe. Figure 1

Nano-scale aluminium interaction in synthetic hydrated calcium silicate gel studied by 29Si MAS-NMR

This research consists of the fabrication of synthetic gels of hydrated calcium silicate (C-S-H gel) and hydrated calcium aluminate silicates (C-A-S-H gel) in aqueous solution oversaturated in calcium hydroxide. These gels were fabricated using nanomaterials with different specific surface area; two nanosilicas (NS), OX50 and A200 (50 and 200m2/g respectively) and two nanoaluminas (NA), A65 and A130 (65 and 130m2/g). Mixtures were carried out maintaining a Ca/Si=2 ratio and variable Al/Si ratios of 0.1, 0.5 and 1. The effect of aluminium incorporation in the C-S-H gel was studied using the nuclear magnetic resonance technique (29Si MAS-NMR), and the information obtained was further processed using the mathematical deconvolution method. Chemical shift bands were delimited to identify the structures. From the results obtained, modifications of the tetrahedral (Qn) in the dreierketten structure were observed in the different combinations, as well as the modification of the bridging tetrahedral (Q2b) due to the presence of aluminium replacing the silica bridging tetrahedron Q2b(1Al). High Q4 values were detected in the C-S-H gel with NS OX50 and this could be associated to a double chain formation very similar to a perfect tobermorite. The length of the mean chains (MCL) was very variable in each blend, but some trends were observed as the Al/Si=1 ratio and the Al/Si=0.1 ratio maintain or increases the MCL respectively. The results are interesting and concrete case mixtures with NS OX50 show original trends that have not yet been reported in the literature.

Deformation and cracking phenomena in cold sprayed 6061 Al alloy powders with nanoscale aluminum oxide films

This paper presents deformation and cracking phenomena associated with the cold spray of nanoscale surface oxide layers associated with the cold spray of 6061 Al alloy powders. The structure of the top surface oxide film was revealed via Focused Ion Beam (FIB), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). The observations show the oxide layer characteristics most likely matches crystalline γ-Al2O3. Phenomena associated with surface contacts, contact-induced elastic-plastic deformation, heating, and cracking are then studied using a combination of analytical models, Finite Element Analysis (FEA) and Molecular Dynamics (MD) simulations. MD simulations are also used to obtain estimates of oxide film young's moduli, strains to failure, and the fracture energies of oxide films. The results from the MD simulations and microscopy observations are incorporated into a bi-linear Johnson- Cook finite element simulations of cold spray contact-induced deformation and cracking due to the impact of aluminum powder particles with nanoscale oxide layers and similar substrates with nanoscale oxide layers. The powder impacts are shown to result in localized splat deformation and heating, along with the cracking of the oxide layers that expose fresh metallic surfaces to high temperature surface contacts (at temperatures above the recrystallization temperature for aluminum/6061 Al) that can give rise to bonding and mechanical interlocking. The implications of the results are then discussed for the design of cold spray processes for the fabrication and repair of 6061 Al structures.

ПОВЫШЕНИЕ ИЗНОСОСТОЙКОСТИ И КОРРОЗИОННОЙ СТОЙКОСТИ ГАЛЬВАНИЧЕСКОГО ПОКРЫТИЯ ХРОМА ПРИМЕНЕНИЕМ НАНОРАЗМЕРНЫХ МАТЕРИАЛОВ

The article presents the results of testing nanocomposition electroplating coatings based on chromium for wear resistance and corrosion resistance. The studied nanocomposite coatings were obtained by co-deposition with nanoscale aluminum oxide particles. Nanoscale particles had a spherical shape and dimensions of 10... 100 nm. The production of nanoscale particles with such parameters was achieved by plasma recondensation of the feedstock. Electroplating chromium coatings were applied from a self-regulating chromium plating electrolyte in solid chrome plating modes. In order to ensure high sedimentation resistance of the electrolyte-suspension, nanocomposition coatings were applied under constant exposure to ultrasound at a frequency of 18 kHz. Tribological tests of the samples were carried out on a friction machine according to the "roller – pad" scheme according to GOST 23.224–86. Corrosion tests of the studied coatings were carried out on a laboratory installation by immersion of the studied samples in a saline solution according to GOST 9.308–85. As a result of laboratory tests for wear resistance, it was found that nanocomposite electrolytic coatings based on chromium have a wear resistance 1.5–1.8 times higher than the wear resistance of chromium base coatings and 2.1–2.2 times higher than the wear resistance of steel SHX15. The corrosion resistance of the chromium-based nanocomposition coating is 1.86 times higher than the corrosion resistance of the chromium base coating and 6.86 times higher than the corrosion resistance of 15X steel. Given the high wear resistance and corrosion resistance of chromium-based nanocomposite electroplating coatings, they should be recommended for use in machine-building and repair production as a way to restore worn parts and strengthen new ones.

ВЛИЯНИЕ НАНОРАЗМЕРНЫХ ЧАСТИЦ ОКСИДА АЛЮМИНИЯ НА МОРФОЛОГИЮ, СТРУКТУРУ И ХИМИЧЕСКИЙ СОСТАВ ГАЛЬВАНИЧЕСКОГО ХРОМА

The article presents the results of studies on the morphology, structure and chemical composition of chromium electroplating obtained by co-deposition with nanoscale aluminum oxide particles. Nanoscale particles were obtained by plasma recondensation of the feedstock. Electroplated chromium coatings were applied from a self-regulating chromium plating electrolyte in solid chrome plating modes with constant exposure to ultrasound on the electrolyte. The morphology and structure of the surfaces of the obtained coatings were studied using a Mira II Tescan scanning electron microscope. As a result of the conducted research, it was found that the introduction of nanoscale aluminum oxide particles into the chromium plating electrolyte leads to a decrease in the grain size of the coating, which entails an increase in the dislocation density and, as a consequence, the microhardness of the resulting coating. The average grain size of the chromium base coating was 1.1 × 10-4 cm, which corresponded to a dislocation density of 2.5 × 108 cm-2 and a microhardness of 9.6 GPa, while the nanocomposite electrolytic coating based on chromium had an average grain size of 7.2 × 10-5 cm, which corresponded to a dislocation density of 5.7 × 108 and a microhardness of 14.32 GPa. The analysis of spectrograms obtained as a result of emission analysis of samples with coatings showed that the nanocomposition electroplating of chromium contains elements of nanoscale particles used to produce it, which are absent in the base coating. This indicates the introduction of nanoscale particles into the coating during its application. The obtained results create prerequisites for further research and development of an algorithm and methodology for controlling the physico-mechanical properties of the coatings obtained by introducing a given number of certain nanoscale particles into them.

A scalable, eco-friendly ultralow-temperature approach to forming Al2O3 water-repellent cotton coatings via UV photo-annealing.

Hydrophobic coatings on cotton fabrics were successfully prepared via solution deposition of a "flat" nanoscale aluminum hydroxo cluster and a photo-assisted anneal using ultraviolet light. The coatings have a low surface roughness and high uniformity confirmed by SEM imaging and elemental analysis. The method represents a robust, scalable, and environmentally benign procedure suitable for industrial processes.

Elastomeric nanocomposite for recovery of worn-out basic parts of agricultural machinery

Due to the high specific surface area of nanoparticles, in comparison with micro-sized particles, a significant improvement in the consumer properties of polymer nanocomposites is achieved at relatively low concentrations of nanoscale fillers (up to 5%). Research and subsequent development of new polymer nanocomposites are of great scientific and practical interest, as they provide further development of promising high-performance technologies for restoring landing holes, increasing the post-repair life of basic parts and reliability and significantly reducing the cost of repairing agricultural machinery. The article describes the influence of metal nanoparticles on the thermophysical and mechanical properties of elastomers, presents the results of experimental studies of the deformation-strength and adhesive properties of a nanocomposite based on F-40 elastomer filled with nanoscale copper and aluminum particles as well as its optimal composition. Comparative data on the heat and heat resistance of the F - 40 elastomer and the nanocomposite based on it are presented.

Smart Electromagnetic Thermites: GO/rGO Nanoscale Thermite Composites with Thermally Switchable Microwave Ignitability.

This effort demonstrates the development of a novel, graphene oxide nanoscale thermite composite with thermally tunable microwave ignitability. A model thermite system containing nanoscale aluminum and nanoscale iron(II) oxide in a stoichiometric ratio (30/70 wt %) was combined with sheets of graphene oxide (GO) or reduced graphene oxide (rGO) using an immiscible two-fluid sonication and tape casting process. The samples were microwave irradiated within a single-mode resonant microwave cavity to determine the microwave ignition delay. Neat thermites were found to ignite after 4.34 s of microwave illumination, whereas 30 wt % rGO thermite composite ignition delay was an order of magnitude shorter (0.43 s). For most samples (4 of 6 trials), it was found that application of a 30 wt % GO coating inhibits microwave ignition of the thermite. Thermal treatment of the GO thermite composite led to switching of thermites from unignitable to ignitable with microwave field application as short as 0.24 s due to GO reduction. Optimum heat treatment time and GO content are explored with SEM, DSC/TGA-MS, Raman, and XPS deconvolution. This effort demonstrates the use of GO and rGO addition to achieve thermally switchable microwave ignitability to electromagnetically shield or enhance nanoscale energetic ignition by microwave energy.

Photoflash and laser ignition of full density nano-aluminum PVDF films

Laser or flash excitation is an attractive ignition option for many energetic systems because of increased safety and control. Commonly used electrical ignition systems are more likely to cause accidental ignition due to stray currents. Upgrading to laser or flash ignition mitigates this problem as well as allowing the ignition at multiple sites more easily for improved control of the energy release. Carbon nanotubes and nanoscale aluminum have been shown to be flash ignitable in loose powders or very porous low-density materials; however, these previous low-density formulations may not be as useful in practical energetic systems. In this study, nano aluminum particles are combined with a polyvinylidene fluoride binder/oxidizer in order to create a full-density photosensitive material. Using a low energy broadband flash source and an Nd:YAG laser at 1064 and 532 nm, films of nano aluminum and polyvinylidene fluoride were successfully ignited experimentally and ignition response was quantified. Solids loading was found to be the dominating factor controlling minimum ignition energies, with the lowest energies observed at 20 to 25 wt.% nAl. Simulations of the wave and particle interactions were modeled with COMSOL Multiphysics® for both the flash and laser-induced heating. The results show that optimal energy absorption occurs at nAl particle fractions of 20–25 wt.%, consistent with the experimental observation. Additionally, the results show the effect of plasmonic resonant enhancement of the heating, specifically at lower wavelengths near 250 nm.