Aluminum Nanopowder Research Articles

Sustainable electric discharge machining using alumina-mixed deionized water as dielectric: Process modelling by artificial neural networks underpinning net-zero from industry

The requirement for materials possessing both high strength and low density has garnered significant attention from industries and researchers in recent times. Among these materials, aluminum 6061 (Al6061) exhibits the desired properties. However, due to its diverse machining capabilities, powder-mixed electric discharge machining (PMEDM) has emerged as a viable option for cutting such materials. This method has been criticized for its high energy consumption and limited cutting efficiency. Furthermore, conventional dielectric (kerosene) employed in EDM has drastic environmental and operator's health concerns. To address the abovementioned issues, deionized water has been employed in this study which enhances the reusability of resources and minimizes the cost of the dielectric. Herein, to make the process sustainable, and to keep the environment free from hazardous fumes, generated during the machining process, deionized water has been used. In addition to that, to uplift the machining responses, alumina (Al2O3) nano-powder has been engaged. To conduct the study, response surface methodology (RSM) was employed. This investigation aimed to analyze the impact on the material removal rate (MRR), surface roughness (SR), and specific energy consumption (SEC) by using microscopy analysis, scanning electron microscopy (SEM), 3D surfaces profilometry, energy dispersive x-ray (EDX) analysis and after that, the machining responses are modelled using the artificial neural networks (ANN) technique. It was observed that by utilizing non-dominated sorting genetic algorithms (NSGA-II) an improvement of 87.42 % in MRR, 3.4 % better surface finish and 0.7 % better SEC have been obtained. Notably, CO2 emissions were found to be 94.27 % lower by using the deionized water as dielectric compared to those produced by kerosene oil.

The mechanical properties of ceramic matrix composite composed of polysilazane-derived silicon oxycarbonitride ceramic with nano alumina

The primary objective of this study is to develop ceramic-based composite materials by synthesizing silicon oxycarbonitride (SiCNO) ceramic from a liquid polysilazane precursor. The SiCNO ceramic powder is incorporated with nano alumina powder, compressed, and pyrolyzed at varying temperatures to produce ceramic bulks. The experimental findings reveal a substantial enhancement in the mechanical properties of alumina with the incorporation of SiCNO ceramic powder. The addition of 10 wt% SiCNO ceramic powder to the alumina ceramic matrix composite results in a 34.5% increase in compressive strength and 41.3% increase in compressive modulus compared to pure alumina. Notably, the sample containing 20 wt% SiCNO ceramic powder in the alumina ceramic matrix, pyrolyzed at 1100 °C, demonstrates a remarkable 151.1% increase in flexural strength compared to pure alumina. These results underscore the effective enhancement of alumina's mechanical properties by SiCNO ceramic powder as a component, while maintaining a relatively low density.

Polymerizable sol–gel synthesis of dark-visible light antibacterial magnetically-recoverable AgBr-loaded iron oxide/alumina nanocomposite

The demand for a facile approach for synthesizing multifunctional nanocomposites is increasingly vital across diverse applications. In this study, a polymerizable sol–gel synthesis has been reported to obtain nanocomposites of magnetic iron oxide deposited over alumina nanopowder. The synthesis is mediated by the deposition of a calculated amount of iron(III) methacrylate, along with ethylene glycol dimethacrylate crosslinker, over alumina nanopowder, followed by thermally-inducing free radical polymerization at 125 °C for 30 min. The powder thus obtained has been subjected to calcination at 400 °C for 150 min and the resultant nanocomposites were characterized using wide-angle x-ray scattering, attenuated total reflectance—Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, field-emission scanning electron microscopy, ultraviolet-diffuse reflectance spectroscopy, vibrating sample magnetometer and Brunauer–Emmett–Teller surface area measurements. The nanocomposites containing 15 and 20 wt% of iron oxide have been found to exhibit a saturation magnetization (M s) value ranging from 12 to 14 emu g−1. To the nanocomposite containing 20 wt% of iron oxide, 5 wt% of AgBr was loaded through thoroughly mixing a surfactant-based precursor, silver-tetraoctyl ammonium bromide (Ag-TOAB), followed by thermolysis. All the nanocomposites have been studied for their antibacterial activity against a representative gram-negative bacterium, Escherichia coli, under dark and visible light conditions. While a 3 mg ml−1 loading of the AgBr-loaded nanocomposite has exhibited complete clearance of the bacterial growth by 90 min in the dark, a similar activity has been observed in 60 min under light. The study has revealed the multifunctionality and high potential of the AgBr-loaded iron oxide/alumina nanocomposite as a promising dual-mode antibacterial and magnetically recoverable photocatalyst material.

Thermo-mechanical characteristics of oxide-coated aluminum nano-powder

This paper presents a comprehensive study on the thermo-mechanical characteristics of oxide-coated aluminum nano-powder, which is a crucial property for their application in powder metallurgy, particularly in warm compaction process. A representative volume element (RVE) of oxide-coated aluminum nano-powder is analyzed under the hydrostatic compression test at different temperatures using the Reactive Molecular Dynamics (RMD) method that can predict the thermal conductivity of nano-powders by incorporating the interaction effects of density and temperature. The thermal conductivity is evaluated based on the Müller-Plathe's reverse non-equilibrium molecular dynamics (rNEMD) method, and the size dependence of the method is investigated. The computational model is validated with the experimental data. The results illustrate that the thermal conductivity of oxide-coated aluminum nano-powder is significantly lower than that of the bulk aluminum due to restricted surface contact between individual aluminum particles. Moreover, it is observed that increasing the density and temperature leads to an increase in the thermal conductivity of oxide-coated aluminum nano-powder.

Explosion characteristics and reaction mechanism of nano-aluminum/methanol fuel spray in a square closed vessel

Nano-aluminum/methanol fuel has broad application prospects in the field of ship and automobile energy, but disasters caused by its spray explosion tend to be ignored. In this study, a 16.2-L visualization sealed chamber was employed to assess the impact of varying aluminum powder blending ratios (from 2 wt% to 15 wt%) on the flame morphology, flame speed, and explosion overpressure of nano-aluminum/methanol fuel spray explosions. The results show that, compared with pure methanol, the spray explosion flame of nano-aluminum/methanol fuel is more continuous and brighter. Within the microscopic flame structure, the agglomeration and combustion of aluminum particles become more evident as the mass fraction of nano-aluminum powder increases. When the aluminum powder mass fraction surpasses 8 wt%, the flame's instantaneous velocity showcases oscillatory propagation patterns similar to those observed in dust explosions. The Pmax and (dP/dt)max of the nano-aluminum/methanol fuel spray explosion initially increase, then decrease with the rise in nano-aluminum powder mass fraction, peaking at 4 wt%. Compared to pure methanol, the enhancements in Pmax and (dP/dt)max are over 23.1 % and 73.3 %, respectively. By integrating the TG analysis of reactants with the SEM analysis of explosion residues, a combustion mechanism for the single droplet explosion of the nano-aluminum/methanol fuel was established. Numerical simulations suggest that nano-aluminum augments the generation rate and quantity of O free radicals via elemental reactions R2 (Al + O2 <=> AlO + O), R4 (AlO + O2 <=> AlO2 + O), and R8 (AlO2 <=> AlO + O). This amplifies combustion reactivity, expedites fuel consumption, and bolsters flame propagation. The research provides empirical evidence supporting the safe application of nano-aluminum/methanol fuels.

Effects of K2SiF6 on Ignition and Heat Release Characteristic of Nano-Sized Aluminum Powders

ABSTRACT This study investigates the effect of potassium fluosilicate (K2SiF6) on the ignition and heat release characteristics of n-Al50, n-Al100, and n-Al800. It is found that K2SiF6 can effectively improve the ignition and heat release characteristics of nano-aluminum powder (n-Al). This is because K2SiF6 effectively increases the reaction rate. The heat release characteristics of the n-Al/K2SiF6 mixture are improved as the particle size of aluminum powder decreases and the heating rate increases. However, when the particle size reaches a certain level, the enhancement effect will become smaller and smaller. The study revealed that the addition of K2SiF6 influences the ignition delay time, reaction, and combustion products of the n-Al/K2SiF6 mixture. A small amount of K2SiF6 can greatly reduce the ignition delay time of nano-aluminum powder. With the increase of K2SiF6 content, the ignition delay time of n-Al50 decreases first and then increases, while the ignition delay time of n-Al100 and n-Al800 decreases continuously but the extent of this reduction progressively diminishes. The morphology and composition of the combustion products were analyzed. This paper found that K2SiF6 fluorinates the oxidized shell of aluminum, thereby promoting its ignition and combustion. The influence mechanism of K2SiF6 on n-Al ignition in air is discussed.

Construction of hollow heterogeneous microspheres containing energy storage fibers by electric spray to promote combustion of nano aluminum

To solve the problem of nano-aluminum (nAl) powder easy agglomeration and improve its thermal reaction, nAl was combined with adhesive (Viton A, F2602) and oxidizer (Ammonium perchlorate, AP) forming microspheres by electrostatic spray method. The morphology and structure were analyzed by SEM, EDS and XPS. The results showed that the microspheres (diameter≈Φ10–15 μm) were hollow structures formed by winding of fluoropolymer fibers, while AP and nano aluminum particles were embedded on the fibers. By controlling the electric spray process, the well-dispersed AP and nAl nanocrystals were assembled on the fiber. Thermal analysis indicated that the gas phase products decomposed by AP were absorbed by porous microspheres, and part of the heat was stored in polymer fibers, thus promoting the breakdown of the alumina shell and accelerating the pre-ignition reaction. The combustion and laser ignition experiments proved hollow heterogeneous microspheres have excellent thermodynamic properties. The assembled microspheres not only solved the problem of poor rheology caused by the agglomeration of nAl, but also improved the insufficient combustion of nAl and the condensation of products.

The effect of size and type of alumina nanopowder phase on the transparency and bending strength of bodies sintered with MgO and La2O3 sintering aid

The effect of size and type of alumina nanopowder phase on the transparency and bending strength of bodies sintered with MgO and La2O3 sintering aid

Development of novel nanocomposite radiation shielding blocks as gamma rays barrier

This work is focused on developing new types of radiation shielding materials using the stereolithography 3D printing technique, which enables the creation of gamma radiation shielding materials in two different sizes. Six different square nanocomposite radiation shielding blocks with an additive ratio of 0.5 wt% were prepared using aluminum nano-powder (nano-Al), copper nano-powder (nano-Cu), calcium nano-powder (nano-Ca), silicon carbide nano-powder (nano-SiC), graphene nano-platelets (GnPs), and eggshell nano-powder (nano-Es). Then, blocks prepared in two different thicknesses (5 mm and 10 mm) were analyzed with Mössbauer spectroscopy utilizing the Co-57 source for γ-ray shielding. The radiation attenuation properties of the developed materials for γ-rays were evaluated. The nano-Cu doped composite block was determined to have the greatest performance in gamma-ray shielding among the specimens mentioned in this investigation. The findings indicate that it is possible to reduce the shield thickness by about 19% compared to neat resin for γ-rays using the determined nano-powders. These experimental findings suggest that the nano-Cu, nano-Ca, and nano-Al reinforced resin nanocomposites are potentially valuable new radiation shielding materials.

Effect of non-uniform magnetic field on combustion products of aluminum nanopowder in mixture with titanium and zirconium dioxides

The morphology and phase composition of the combustion products in air of Al nanopowder mixed with diamagnetic TiO2 and ZrO2 was studied. The influence of non-uniform magnetic field on the combustion process of the oxide-metal powdery mixtures led to the stabilization of TiN and ZrN in the final products. The two-level whiskers of AlN formed at the combustion of Al-TiO2 mixture, while the agglomerated structures covering the large particles of ZrN formed at the combustion of Al-ZrO2 mixture. During combustion of oxide-metal mixtures in non-uniform magnetic field, diamagnetic metal dioxides are reduced to metals or their suboxides and then interact with atmospheric nitrogen.

Role of structural disorder in the vibrational spectra of sol–gel [formula omitted] and [formula omitted]-Al[formula omitted]O[formula omitted] nanoparticles

Alumina nanopowders belonging to the γ and δ transition phases have been characterized by infrared and Raman spectroscopies. A quantitative interpretation of their vibrational spectra has been provided and related to their crystal structure, with particular emphasis on structural disorder and features not predicted by group-theoretical considerations. Both phases show very similar infrared dielectric functions, but with clear instances of mode-splitting in the δ phase, which are related to ordering in the tetrahedral Al positions. Raman spectroscopy was unable to resolve any modes in the sample identified as γ phase, but the full lattice vibrational region could be measured for the δ sample under UV and red excitation lines. Raman spectra are more complex than those obtained by infrared spectroscopy and cannot be completely explained by factor group analysis, in the absence of dedicated theoretical studies. Finally, the luminescent properties of these materials have been qualitatively explored and linked to disorder and substitutional impurities. In general, the results contained in this work prove that vibrational spectroscopies are powerful tools for quantitative analyses of these disordered nanomaterials and suggest the need for more theoretical work to understand their vibrational properties.

Catalytic pyrolysis of oil sludge using the nano alumina powder

Catalytic pyrolysis of oil sludge using the nano alumina powder

Numerical development for freezing of phase change material loading nanoparticles for improving water treatment

The container with a wavy insulated wall and one branch shaped fin has been applied in this study. The process of freezing was simulated based on implicit way via Galerkin approach. The testing material is a mixture of H2O and nano-powders of alumina. The fraction of additives is less than the critical value for assumption of single phase mixture. Verification test has demonstrated the correctness of the modeling procedure. The utilizing denser mesh close the region of ice front makes the accuracy of modeling to increase. Owing to the negligible speed of liquid water, the associated terms in governing equations have been discarded. Regarding the utilized diameter of alumina, dp = 40 nm is the best option which leads to a lower period of freezing. With dispersing alumina with optimum size, the solidification time declines about 41.22 %.

Hydrogen production by oxidation of aluminum nanopowder in water under the action of laser pulses

The possibility of hydrogen production by the action of laser pulses (1064 nm, 14 ns, 10 Hz, 0.5–6 J/cm2) on a suspension containing 0.03 wt % aluminum (100 nm) in water is shown. It was found that aluminum nanoparticles absorb the laser energy and heat up. As a result of heating, the continuity of the oxide film is disrupted, and metallic aluminum reacts with water. It is shown that there is a complete transformation of aluminum into products (gibbsite, boehmite, bayerite). The maximum hydrogen yield Vm = 8.4 mL does not depend on the energy density of the laser radiation. The time to reach Vm decreases according to the hyperbolic law with increasing laser energy density, reaching 3.5 min at an energy density of 6 J/cm2.

Application Process of Coating Agent and the Coating Effect Evaluation Based on Molecular Dynamics.

In the field of energy-containing materials, the modification of nanoaluminum powders has been widely studied. However, in modified experimental design, the lack of theoretical prediction usually leads to long experimental cycles and high resource consumption. To this end, this study evaluated the process and effect of dopamine (PDA)- and polytetrafluoroethylene (PTFE)-modified nanoaluminum powders based on molecular dynamics (MD). Through the calculation of the coating stability, compatibility, and oxygen barrier performance of the modified material, the modification process and effect were explored from a microscopic point of view. The results showed that the adsorption of PDA on the nanoaluminum was the most stable, and the binding energy was 463.03 kcal·mol-1. PDA and PTFE with different ratios are compatible systems at 350 K, and the best compatibility ratio is 10 wt % PTFE/90 wt % PDA. The 90 wt % PTFE/10 wt % PDA bilayer model has the best barrier performance for oxygen molecules in a wide temperature range. The calculated results of the coating stability agree with the experiments, and it is pointed out that it is feasible to evaluate the modification effect in advance by MD simulation. In addition, the simulation results concluded that the double-layered PDA and PTFE have better oxygen barrier properties. Compatibility can be used only to determine whether phase separation occurs between mixtures and is not directly related to the dense mixing of polymers and the barrier properties of small gas molecules. The simulation provided in this article can predict the experimental results and provide theoretical guidance for coating modification experiments in order to reduce unnecessary experiments, shorten the experimental cycle, and reduce costs.

Influence of machining duration of 0.8SiO2/ 0.2Al2O3 nanopowder on electrochemical characteristics of lithium power sources

This paper highlights the relationship between changes in the electrochemical properties vs grinding duration of mixed nanosilica and nanoalumina powders. The dependence of the electrochemical characteristics on structural and morphological changes in the nanocomposite powder has been elucidated. A study of the electrochemical characteristics was performed in galvanostatic and potentiodynamic modes. Scanning electron spectroscopy (SEM), X-ray diffraction analysis (XRD) and ultra-soft X-ray emission spectroscopy (USXES) were used to determine the grinding duration effect on the structural and morphological characteristics. It have been found that as a result of increasing duration processing, the composite is compacted due to O-Opπ-interaction between surface atoms of nanoparticles. From the results of electrochemical studies, it has been found that the changes in specific structural features lead to changes in the discharge capacities of lithium power sources. Namely, an increase in grinding time to 5 min leads to increase in charge capacity of first cycle and capacity after 50 cycles. However, with increasing grinding duration to 10, 15 and 20 min is accompanied by a decrease in the charge state of oxygen, specific surface area and increasing of coherent region scattering that lead to a decrease in the discharge capacity.

Thermal reaction characterization of nano-aluminum powder at different heating rates by synchronous thermal analysis

Thermal reaction characterization of nano-aluminum powder at different heating rates by synchronous thermal analysis

ВИЗУАЛИЗАЦИЯ ГОРЕНИЯ НАНОПОРОШКОВ МЕТАЛЛОВ СПРИМЕНЕНИЕМ ИМПУЛЬСНОГО И НЕПРЕРЫВНОГО ЛАЗЕРОВ ПОДСВЕТКИ

The work is devoted to the development of the method for high-speed imaging of high-temperature combustion processes using laser illumination. The object of visualization was a sample of aluminum nanopowder, which combustion temperature reaches 2500 K and is accompanied by a bright glow that varies in a wide range during combustion. It is demonstrated that laser illumination expands the capabilities of a high-speed imaging system and allows a more detailed study of the surface of samples compared to passive imaging by installing a neutral or band-pass filter in front of the high-speed camera lens. Various options for imaging with the installation of light filters with different transmission are considered. To monitor the surface of a burning material with a high-speed video camera in a wide temperature range of an object, it is proposed to use a low-power illumination from a continuous wave solid-state laser or a pulsed laser, as well as a beam expander for uniform illumination of the surface. The results of imaging using illumination from a solid-state laser with a wavelength of 532 nm and a copper bromide vapor laser with a wavelength of 510.6 nm are compared. It is shown that the output power of a solid-state laser of 200 mW with an illumination area diameter of 20 mm is sufficient to visualize “through the flame” the surface of a burning aluminum nanopowder at a low-temperature stage of combustion up to temperatures of ~1950 K. The uniform illumination of the surface can be ensured both by using a diffuser located directly near the sample, and with the use of a telescopic beam expander. Theoretical estimates and experimental results demonstrate that the illumination average power of 200 mW, regardless of the type of laser, is not enough to visualize the surface of a burning aluminum nanopowder at the high-temperature stage. The possibility of complete suppression of illumination during combustion with a temperature above 2500 K will appear when using an illumination laser with an average power of &gt;3,35 W. The proposed illumination technique based on a solid-state laser has advantages in terms of reliability and simplicity compared to known systems based on copper or copper bromide vapor lasers.

МАЛОГАЗОВЫЕ НАНОТЕРМИТЫ И ОТНОСИТЕЛЬНАЯ СИЛА ВЗРЫВА СМЕСИ Аl/MoO3С ФТОРПОЛИМЕРОМ

The common and most studied nanothermic compositions of various compositions are briefly considered and the results of an experimental comparison of the relative explosion force of mixtures of Al/MoO3 nanopowders with fluoropolymer are presented. Systems are presented, the main representatives of which are nanothermic composites for PIR automation and microinitiators. The problem of developing gas-free (low-gas), fast-burning pyrotechnic compositions based on nanothermites is considered. In the experimental part, the effect of the fluoropolymer F-42L on the relative explosion force of a pyrotechnic composition based on a thermite reaction between aluminum nanopowders (burning) and molybdenum oxide (oxidizer) is discussed. It was shown that the fluoropolymer reduces the relative explosion force of the nanocomposite, and the determining chemical reaction of the explosive transformation of the Al/MoO3/F-42L mixture is the reaction of Al with the fluoropolymer.

Thermal reaction characteristics and microstructure evolution of aluminium nano-powder in various mixtures of oxygen and nitrogen atmosphere

Aluminium nano-powder has a small particle size, large specific surface area, and high surface energy, therefore when using it, the risk of fires or explosions is high. In this study, synchronous thermal analyser was used to determine the thermal reaction characteristics of aluminium nano-powder for various oxygen and nitrogen mixtures. The results showed that the oxidation behaviour of aluminium nano-powder could be considered to occur in four stages, according to the characteristic temperature points and polymorphic phase changes. Under experimental heating rates of 5, 10, 15, and 20 K/min, the mass gain and thermal effects of the samples were tested, and also for different oxygen concentrations of 9, 15, and 21 vol%. Changes in the microstructure of the samples were analysed. Oxide layer thickness was found to increase as temperature increased, and this trend was the same for mass change. Surface morphology images of the aluminium particles exhibited agglomeration, melting deformation, rupture, and fragmentation at the different pretreated temperatures of 500, 650, 800, and 900 °C. The results of this study could be used as a basis for exploring oxidation kinetics, and had significance for explosion-proofing technology, particularly with respect to aluminium nano-powder.