Aluminum Powder Research Articles

Spreading anomaly semantic segmentation and 3D reconstruction of binder jet additive manufacturing powder bed images

Variability in the inherently dynamic nature of additive manufacturing introduces imperfections that hinder the commercialization of new materials. Binder jetting produces ceramic and metallic parts, but low green densities and spreading anomalies reduce the predictability and processability of resulting geometries. In situ feedback presents a method for robust evaluation of spreading anomalies, reducing the number of required builds to refine processing parameters in a multivariate space. In this study, we report layer-wise powder bed semantic segmentation for the first time with a visually light ceramic powder, alumina, or Al2O3, leveraging an image analysis software to rapidly segment optical images acquired during the additive manufacturing process. Using preexisting image analysis tools allowed for rapid analysis of 316 stainless steel and alumina powders with small data sets by providing an accessible framework for implementing neural networks. Models trained on five build layers for each material to classify base powder, parts, streaking, short spreading, and bumps from recoater friction with testing categorical accuracies greater than 90%. Lower model performance accompanied the more subtle spreading features present in the white alumina compared to the darker steel. Applications of models to new builds demonstrated repeatability with the resulting models, and trends in classified pixels reflected corrections made to processing parameters. Through the development of robust analysis techniques and feedback for new materials, parameters can be corrected as builds progress.

Energy release effect of micro-nano self-assembled aluminum powders and application in composite explosives

Nano aluminum powder effectively enhances reactivity, thereby improving energy-containing materials' performance. To investigate micro-nano self-assembled aluminum powders' energy output and their application in composite explosives, we tested the heat of combustion and ignition characteristics (ignition delay, ignition energy, flame propagation speed) using oxygen bomb calorimetry and Hartmann tube. Results showed that the combustion heat decreased with increasing nano aluminum powder content. The addition of nano aluminum powders substantially decreased ignition delay and energy, enhancing the combustion rate and reactivity of aluminum powder dust. The ranking of reactivity among the five aluminum powders was as follows: μ@n-Al-10 % > μ@n-Al-5% > μ/n-Al-10 % > μ/n-Al-5% > μAl. Assessing explosives containing various aluminum powders showed that the self-assembled 5 % content sample had the highest heat of detonation at 8490 kJ/kg. Mechanical sensitivity increased with higher nano aluminum powder content, with explosives containing 5 % nano content exhibiting the highest safety performance.

INFLUENCE OF ALUMINA PARTICLES (AL2O3) ON PHYSICO-MECHANICAL BEHAVIOR OF ADDITIVE MANUFACTURING- DLP RESIN USED FOR RAPID TOOLING

Over the past decade, additive manufacturing (AM) has gained considerable recognition in rapid tool manufacturing owing to its notable advantages. For the rapid injection mold manufacturing by the DLP-AM method, the most important subject that should be focused on is the photopolymer resin, as the 3D printed mold must withstand the stresses and temperatures encountered by the injection pressure and temperature of the molten plastic. This study aimed to investigate the effect of adding alumina (Al2O3) powder on the properties of a DLP-AM photopolymer. For this aim, 2 and 4 wt.% Al2O3 were added to a photopolymer resin, and 3D-printed samples were produced by DLP. Several physico-mechanical properties were studied compared to the pure polymer. The results indicated that as the Al2O3 content increased, the void fraction, volumetric heat capacity, wear resistance, tensile and flexural strength, all decreased. In contrast, as the Al2O3 wt.% increased, so did the flexural strain, impact strength, hardness, and thermal conductivity. This study showed that injection molding cycle times can be shortened considerably due to this benefit, which would be beneficial for quick molding applications. Keywords: Rapid tool manufacturing, polymer composites, 3D printing, alumina, Al2O3, photopolymer, additive manufacturing.

Solution of the plane thermoelasticity problems based on a new set of equations

The interaction of thermal and mechanical fields in modern technologies for the synthesis and processing of materials attracts more and more attention. This is due to the need to predict the behavior and properties of new materials and products depending on the conditions of their creation. In the present work, attention is focused on the comparison of the solutions to the thermoelasticity plane problems with and without accounting for the temperature dependence of the material properties. It is assumed that an external heat source traveling over the surface with a specific velocity and following a given trajectory is responsible for a significant temperature increase. It may correspond to a laser source, for example. The new way of problem formulation in stresses is used. The temperature dependence of the characteristics leads to nonlinear thermoelasticity equations when the equilibrium equations, the requirement of strain compatibility, and the Duhamel-Neuman relation for the plane stress state case are combined. To determine the temperature field, a nonlinear thermal conductivity equation is used. To solve the problem numerically, the use of an implicit finite-difference scheme and coordinate splitting for the thermal conductivity equation and the finite-difference method of successive over-relaxation with Chebyshev acceleration for the equations for stresses was made. As a result, the difference in the solution of linear and nonlinear problems is demonstrated for the considered cases. Using the example of a mixture of titanium and aluminum powders, numerical modeling demonstrated that some stress components can reach values up to 3.5 times higher than those obtained in the case of temperature-independent material properties when there is a 500-degree local temperature increase.

Preparation and Properties of Conductive Aluminum Powder (Al@Si@C) for Water-Borne Heavy-Duty Anticorrosive Coatings

Preparation and Properties of Conductive Aluminum Powder (Al@Si@C) for Water-Borne Heavy-Duty Anticorrosive Coatings

Experimental investigation of hybrid reinforced A356 aluminium alloy synthesised by stir casting technique

Abstract One of the most significant alloys to be employed in the automotive, aerospace, and military industries in recent years is A356 aluminium. Because of A356's excellent compatibility with other metals and nanoparticles, novel hybrid composites may be made using it. The characteristics of these hybrid composites are mostly the result of the additives' interaction with the A356 alloy's current elemental composition. Aluminium composites were synthesized through stir casting method by reinforcing 2%, and 4% SiC, 2% and 4 % Al2O3 and 0.5%, 1%, 1.5%, 2% and 2.5% SiC and Al2O3 both. The homogeneous distribution of SiC and Al2O3 microparticles in reinforced composite is revealed by scanning electron microscopy (SEM). The addition of SiC and Al2O3 reinforcements greatly improved the mechanical characteristics of the synthesised composites; for example, a composite with 4% SiC reinforcement reached its maximum hardness and maximum tensile strength of 165 HV and 257MPa respectively. Maximum elongation of 6.72 % was observed for 0.5% SiC and 0.5% Al2O3 reinforced composite. Minimum wear rate is observed for 4% SiC reinforced composite material. This study aims to identify gaps in the potential variations and compatibility of various additives with one another in order to create a brand-new hybrid reinforced alloy suitable for automotive braking system applications: brake rotors made of a disc or a brake pad, depending on the properties of the hybrid reinforced alloy that was made. Hence, the current work presented focuses on the preparation of hybrid reinforcement of A356 with silicon carbide and alumina powders.

Optimization of Foams-Polypropylene Fiber-Reinforced Concrete Mixtures Dedicated for 3D Printing.

The continued global urbanization of the world is driving the development of the construction industry. In order to protect the environment, intensive research has been carried out in recent years on the development of sustainable materials and ecological construction methods. Scientific research often focuses on developing building materials that are renewable, energy-efficient, and have minimal impact on the environment throughout their life cycle. Therefore, this article presents research results aimed at developing a concrete mixture using cement with reduced CO2 emissions. In the context of increasing ecological awareness and in line with European Union policy, the development of a mixture based on environmentally friendly cement is of key importance for the future development of the construction industry. The article compares the physical properties of two mixtures, their foaming possibilities, and the influence of the added polypropylene (PP) fibers on the strength properties of the produced composites. It was found that bending strength and compressive strength were highest in the material with silica fume and aluminum powder at 5.36 MPa and 28.76 MPa, respectively. Microscopic analysis revealed significant pore structure differences, with aluminum foamed samples having regular pores and hydrogen peroxide foamed samples having irregular pores. Optimizing aluminum powder and water content improved the materials' strength, crucial for maintaining usability and achieving effective 3D printing. The obtained results are important in the development of research focused on the optimization of 3D printing technology using concrete.

Hydrogen production from aluminum-water reactions at low Temperatures: based on an in-situ two powders of different particle sizes

To investigate the granule reaction of two-micron aluminum powders with water at low temperatures, differential scanning calorimetry was used to analyze the initial exothermic temperature. Additionally, adiabatic accelerated calorimetry was employed to study the exothermic reaction under adiabatic conditions. The hydrogen production and particle size variation were investigated in order to gain insights into the Al-water reaction in a reactor with no induction time. Through focused beam reflectance measurement analysis, it was observed that during the reaction process of Al-water, particle sizes initially increased and then decreased. Specifically, the particle size of 3 µm aluminum powder experienced a 189% increase after the reaction while 25 µm aluminum powder decreased by 29%. Ultimately, both types of particles reached similar final sizes around 13.89 µm. The process of Al-water reaction was explained and hydrogen production was analyzed, and the kinetic model was obtained.

Synthesis and electrochemical characteristics of metal nanoparticles decorated composite anode made of domestic alloy, used in lithium ion batteries

In this work, appropriate material selection and process design enable the succesful production of high energy density electrode active material in the form of XAZ (where X, A and Z stand for electrochemically active, electrochemically inactive and carbon materials, respectively). Herein, the precipitates rich in iron and chromium are extracted selectively from a local ferrochromium alloy utilizing hydrometallurgy procedures. The precipitates are then exposed to separate calcination to get iron-rich and chromium-rich oxides seperately. In the end, a composite (XAZ) is fabricated under the mild synthesis conditions by combining these oxides with activated carbon and aluminum powder in a planetary ball mill. The composite's morphological, structural, and chemical properties are all optimized. The galvanostatic test results clearly demonstrate that the powder made of XAZ composite with embedded metal nanoparticles delivers 798 mAh g-1 after 100th cycle under a current load of 50 mA g-1 and high capacity (600 mAh g−1) over 300 cycles with an exceptional rate performance. It is anticipated that this research will create novel opportunities for producing high-value electrode active materials from accessible, low-cost raw ingredients.

Study of powders for sintering SiC in the presence of a liquid phase

In this study, nanometric powders of silicon carbide (SiC), micrometric alumina (Al₂O₃) and yttria (Y₂O₃), with specific characteristics provided by the manufacturers, were used to investigate the compaction behavior and the resulting properties after sintering. The SiC used has a purity of over 99% and a particle size distribution with a d50 of 40 nm, while Al₂O₃ and Y₂O₃ have purities of 99.8% and 99.995%, respectively. The morphological evaluation of the powders was carried out using scanning electron microscopy (SEM), while the apparent density analysis was conducted using gas pycnometry. SiC mixtures with 1% and 5% Al₂O₃ and Y₂O₃ were prepared and subjected to uniaxial compaction tests to determine densification behavior under different pressures. The results of this study are relevant to the development of ceramic materials with optimized properties for a wide range of industrial applications. The addition of small amounts of oxides to SiC does not compromise its compaction properties, maintaining the effectiveness of the sintering process and resulting in materials with high density and improved mechanical properties.

Selecting the suitable thermoplastic elastomer as the main component in the feedstock for metal material extrusion of aluminium

Metal material extrusion (MMEX) involves the systematic deposition of material layer by layer, followed by debinding and sintering to produce fully dense metallic parts. The feedstocks, initially comprising metal powder and a binder system, are pivotal in determining processability and final properties. This study utilized polylactic acid (PLA) as the backbone and a thermoplastic elastomer (TPE) as the primary, solvent-debindable component in the binder system, with a 50 and 55 vol% aluminium (Al) powder content. PLA was selected due to its lower degradation temperature and to try to increase the sustainability of the MMEX process. An initial experimentation with various TPEs, employing thermal analysis (TGA and DSC), rheological behavior assessment, mechanical property testing, contact angle measurement, and solvent debinding processes, aimed to identify the most suitable TPE for this study. The results demonstrated that a very low interfacial tension between PLA and TPE is not desirable, as it may result in the removal of some powder particles during the solvent-debinding process. The TPE type with lower viscosity, optimum interfacial tension with PLA, low residue after degradation, adequate rigidity, and flexibility is proper for use as the soluble part of the binder system. After selecting of the appropriate TPE, the printability at a nozzle temperature of 270 °C was undertaken. The solvent debinding process for printed samples was conducted at room temperature. The results indicated that 90 wt% of the TPE was removed successfully from the samples printed with 30 vol% PLA in binder formulation without any defects during solvent debinding.

Influence of foaming additives on the porous structure and properties of lightweight geopolymers based on ash–slag waste

Lightweight geopolymer is a promising thermal insulation material that conserves energy used for heating and cooling buildings. This study investigates foaming agents that influence the porous structure and properties of geopolymer foams based on ash–slag waste from thermal power plant using a 12 M sodium hydroxide solution, waterglass, and foaming agents (30 % hydrogen peroxide solution, aluminum, silicon, and zinc powders). The study demonstrates the feasibility of foaming geopolymers by water evaporation without foaming additives, where the best density of 949 kg/m3 and compressive strength of 4.2 MPa were achieved in samples foamed by microwave radiation, but such properties cannot attribute geopolymers as lightweight. Foaming with H2O2 is hard to synchronize with geopolymerization reactions. Aluminum and silicon powders lead to rapid reactions in alkaline conditions, resulting in uneven pore sizes. Zinc powder was the most effective foaming agent, producing materials with a density of 331 kg/m3 and compressive strength of 1.17 MPa, and it also integrates into the geopolymer gel structure. The foaming process should occur at room temperature. Elevated temperatures increase curing rates and result in incomplete geopolymerization, preventing uniform pore formation. Synthesized geopolymers are suitable for building insulation, basements, underground pipelines, and utility networks.

Feasibility of using ground Al-Al2O3 composite powders in laser powder bed fusion

The reincorporation of residues in the productive cycle helps reduce CO2 emissions and non-renewable resources extraction. Therefore, the present work studies the feasibility of reincorporating an aluminum residue in the productive cycle by means of an additive manufacturing technique. In this context, other issues considered are the importance of aluminum alloys, the improvement of their properties by adding alumina making composites materials, and issues that must be overcome when printing parts by laser powder bed fusion using a mix of Al and alumina powders. This work evaluates the suitability of Al alloy - alumina composite powders obtained by grinding Al alloy chips from sawing. Laser power and scanning speed were varied until the designed samples were obtained. The findings show that is possible to use powder obtained by grinding Al chips in the laser powder bed fusion technique to obtain Al-Al2O3 composites which exhibits hardness of 226 HV ± 34.3.

Preparation, characterization and thermal properties of nitrographene coated aluminum powder

AbstractAluminum powder is commonly used as a metal fuel additive in composite solid propellants. However, its tendency to agglomerate during combustion can lead to two‐phase flow losses, negatively impacting its energy performance. To address this issue and enhance the combustion performance of aluminum powder, nitrated graphene oxide (NGO) was developed to improve aluminum dispersion and optimize its energy characteristics. Various analytical techniques were employed to examine its properties, including Fourier‐transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), elemental analysis (EA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TG). Al/NGO composite was prepared using a solution‐assisted method in N, N‐dimethylformamide (DMF) and characterized by SEM, XPS and X‐ray diffraction (XRD). The ignition characteristics and heat of combustion of Al/NGO powder were measured using a laser igniter and an oxygen bomb calorimetry. The appropriate mass ratios of NGO coating had positive effects on the ignition and combustion of Al. Specially, 4 % NGO coating reduced Al ignition energy by 46.5 % and increased the Al combustion efficiency by 22.0 %. Moreover, the catalytic effect of Al/NGO on the thermal decomposition of ammonium perchlorate (AP) was investigated using differential thermal analysis (DTA). Results showed that two‐stage pyrolysis paths of AP tended to merge into a single pyrolysis process when Al/NGO4 % was added. The most favorable catalytic effect on AP′s thermal decomposition process was produced with the addition of 10 % Al/NGO4 %, reducing the activation energy by Kissinger equation for high‐temperature decomposition to 107.7 kJ mol−1. These findings may provide valuable insight for enhancing the performance of aluminum powder in energetic materials through NGO modification.

Analysis of magnesia-carbon bricks erosion in vanadium extraction converters: Insights from dynamic experiments and interface characterization

This paper uses a rotary furnace to simulate the dynamic erosion behavior of various magnesia-carbon bricks within a vanadium extraction converter, focusing on the effects of carbon content and antioxidants on erosion. The results indicate that vanadium-rich slag primarily consists of oxide solid solutions, iron vanadium spinel, and metallic Fe. Adding aluminum and silicon powders to the bricks reduces apparent porosity, increases body density, and improves slag erosion resistance. However, an increase in carbon content (12.54 wt% to 18.59 wt%) within magnesia-carbon bricks correlates with decreased high-temperature strength, exacerbating the reaction propensity with slag and consequent structural damage. Analysis of the interface phase between magnesia-carbon bricks and vanadium slag reveals a predominance of metal phase, spinel phase, and liquid slag phase. Thermodynamic calculations suggest an initial reaction between MgO and C on the brick surface, yielding Mg vapor and CO gas, while C reacts with slag to produce Cr and V elements, leading to surface structure degradation. Subsequent slag encasement and dissolution of remaining MgO via decarburization channels further erode magnesia-carbon bricks. Cumulative erosion iterations ultimately culmi nate in performance failure of magnesia-carbon bricks.

Mechanical properties of aluminum matrix composite reinforced with titanium carbide

Abstract An original method for the production of metal matrix nanocomposites has been proposed, which consists of depositing carbide structures 4–12 nm thick onto the surface of particles of aluminum powder by molecular layering, mixing the resulting dispersed particles with particles of pure metal in the required concentration, then pressing and sintering the resulting mixture. The resulting workpieces are subjected to intense plastic deformation by high-pressure torsion, which not only significantly reduces porosity, ensures a uniform distribution of reinforcing particles throughout the volume, and destroys carbide shells on the surface of dispersed particles, but also grinds aluminum particles. Experimental stress-strain curves of the synthesized composites were constructed and the contribution of various hardening mechanisms to the final hardening of the metal matrix composite was assessed. In metal matrix composites synthesized by this method, with small fractions of the volume content of reinforcing titanium carbide particles (less than 0.1%), almost twofold hardening and a threefold increase in the yield strength are observed with a slight reduction in plastic deformation before failure.

Enhancement of aluminum powder reaction behavior at high temperatures—Aluminum powders with “sea urchin structure” coated by AP

To solve the problem of high ignition temperature of aluminum powder and easy to burn into blocks at high temperatures, “sea-urchin-structured” aluminum powders (μAl@nAl) obtained by electro-explosion were coated by ammonium perchlorate (AP) on its surface. AP in a high-temperature environment has a rapid decomposition, then the gas production will promote the dispersion of aluminum powder into micro-clusters, thus preventing the aluminum powder agglomeration during the combustion process. The micro-nano composite aluminum powder (μAl@8 %nAl) and physical mixed aluminum powder (μAl + 8 %nAl) coated by AP were completed by solvent volatilization method. The coating surface was observed by scanning electron microscopy. The heat of combustion and pressure curves for different AP contents were tested using a chamber with a constant volume, and the ignition and combustion performance of the AP samples were investigated using a carbon dioxide (CO2) laser ignition device. The AP samples shortened the ignition delay time and improved the combustion performance in the fixed-volume combustion and laser ignition tests. Under atmospheric air, taking into account the theoretical calorific value, pressure curve, and combustion performance, the optimal AP content is 10 %. The thermal decomposition process of two samples was further analyzed using the thermogravimetric and differential scanning calorimetry (TG-DSC) method. The decomposition of AP advanced the first oxidation peak of aluminum powder; however, in the second step oxidation peak, the peak temperature of μAl@8 %nAl@10 %AP sample was delayed compared to μAl + 8 %nAl@10 %AP sample. High-voltage electrical explosions and high-energy laser-induced air shock waves were created to simulate the high-temperature environment of the detonation reaction zone, and pictures of the reaction process and pressure change curves of the “sea urchin structure” aluminum powder coated by AP at high temperatures were recorded. The results showed that the “sea urchin structure” aluminum powder coated by AP exhibited better combustion performance, and the reaction degree of the aluminum powder had been deepened.

Effects of aluminum particle size on metal acceleration for CL-20-based aluminized explosives

The addition of aluminum (Al) powder to CL-20 significantly enhances the overall energy of mixed explosives. Nonetheless, the metal acceleration ability of explosion after Al addition shows unpredictable behavior due to the unclear reaction characteristics of Al in CL-20 detonation products. This study utilizes a plate push test employing CL-20-based aluminized explosives to acquire the reaction degree formulation for Al powder with varying particle sizes in a CL-20 detonation environment. Moreover, it elucidates the reaction mechanism of microsized Al particles during the initial phase of afterburning. Additionally, this reaction formulation enhances the equation of state (EOS) for CL-20-based aluminized explosives. Subsequently, the new EOS is implemented in LS-DYNA to simulate the metal flyer acceleration process. Consequently, the impact of Al particle size on the metal acceleration capability of aluminized CL-20 is examined. The results indicate that for CL-20-based aluminized explosives with 15 % Al content, an optimal Al particle size of 34.12 μm exists when the particle size exceeds 10 μm. This optimum increases the speed of the driving metal plate by 7.4 % compared to CL-20/LiF explosives.

Factors affecting the expansion ratio and flow consistency of expandable foam grout for subsurface improvement

Highly porous cementitious materials have been utilized in various geotechnical applications, such as filling subsurface cavities, backfilling, and enhancing loose layers. In particular, expandable foam grout (EFG) has significant potential for cavity filling owing to its unique characteristics such as volume expansion and high flowability. Various EFG samples were prepared by mixing water, cement, aluminum powder, bentonite, and an accelerator at various ratios. Cementitious materials with various mixing ratios have different volume expansion and flowability, and each ingredient causes different impacts on their properties. This study investigated the effects of aluminum and bentonite contents on volume expansion and flowability. Expansion ratios and flow consistencies were estimated from expansion and flow tests. The results show that the expansion ratios increased with increasing aluminum content regardless of the water-cement ratio while slightly decreased with increasing bentonite content within a given range of ingredient contents. Moreover, the flow consistency increased with increasing water-cement ratio and decreasing aluminum and bentonite contents. The properties were evaluated using EFG mixtures containing relatively high bentonite contents to observe the effects of bentonite on a wide range of cementitious materials with varying bentonite contents. The expansion ratios and flow consistencies of the EFG mixtures containing relatively high bentonite contents decreased steeply with increasing bentonite content. Finally, the ingredient effects on volume expansion and flowability were discussed to design the mixture depending on its purpose.

Preparation and Decomposition of Spherical CL-20 Composites with Enhanced Laser Absorbance and Decreased Mechanical Sensitivity.

Direct initiation of secondary explosives by a semiconductor laser is highly demanded, but it is challenging to exclude the use of sensitive primers. Most laser-sensitive energetic materials are usually mechanically sensitive. In order to reduce the mechanical sensitivity (MS) of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) while improving laser absorbance in the near-infrared band, spherical CL-20 composites (SCCs) embedded with nano aluminum (Al) powder and graphene-based catalyst (GO-CHZ-Co) were prepared by a spray drying method. These SCCs have been characterized comprehensively in terms of their morphologies, particle size distribution, laser absorbance, thermal decomposition behaviors, MS, and laser ignition properties. Results show that the maximum critical impact energy of SCCs was 3.8 J, which is 2.8 J higher than that of pristine ε-CL-20. The critical friction load was increased by at most 108 N compared to pristine CL-20. The absorbance has also been significantly increased up to almost 70% in the wavelength between 400 and 1400 nm, where the peak absorption is located in the region of 800-900 nm. In addition, the initial decomposition temperature (Ti) of SCCs is lower than that of pure CL-20, especially in the presence of GO-CHZ-Co. The apparent activation energy (Ea) for the decomposition of SCCs was largely dependent on the particle size of Al. Preliminary ignition tests indicate that the SCCs can be ignited successfully by a small-power laser.