Porous Aluminum Foam Research Articles

Numerical investigate on the heat transfer performance and mechanical analysis of a water sublimator

Water sublimators play a critical role in efficiently managing the high thermal load of spacecraft in a vacuum environment, ensuring their proper functioning. This article focuses on a novel cold plate water sublimator driven by a porous sublimation tube structure, which is still in the theoretical research stage. Numerical methods are employed to study the evaporation, freezing, and sublimation processes, with validation against experimental data. The average absolute error of the four operating conditions is 1.33 K, and the ice layer thickness error is 8.33 %. Additionally, a method to calculate the effective thermal conductivity of porous aluminum foam is proposed, with a model error of 9 %. The sublimator's heat transfer characteristics are significantly influenced by the porosity of the aluminum foam and sublimation tubes. The impacts on temperature behavior, ice thickness, feed water pressure, and stress are carefully examined. Results reveal aluminum foam porosity of 0.7 and sublimation tube porosity of 0.3. Moreover, the study explores how different heat loads affect the sublimator's operation mode. Heat loads above 2 W/cm2 cause evaporation and dryness within the sublimation tube, while excessively small heat loads lead to ice formation and increased stress on the aluminum foam structure. These findings provide valuable insights for water sublimator design.

The mechanical characteristics of an aluminum foam winding CFRP composite structure under axial compression

To enhance the energy absorption properties of the energy-absorbing structure, carbon fiber-reinforced polymer (CFRPs) with higher specific energy absorption and porous material aluminum foam with better compressive characteristics were organically combined, and a lighter aluminum foam winding carbon fiber-reinforced polymer structure (CFRP-FA-FW) was designed. Through quasi-static compression testing, the deformation mode and energy absorption properties of CFRP-FA-FW under axial load were examined. The energy absorption and specific energy absorption of CFRP-FA-FW are both increased by 113.55 % and 60.73 %, respectively, compared to the simple composite structure CFRP-FA. Finite element simulation was used for the parametric analysis of the CFRP-FA-FW structure to assess the effects of the relative density of the aluminum foam, the fiber lay-up angle, and the thickness. The results reveal that the change in the relative density of aluminum foam has little impact on the failure deformation mode of CFRP-FA-FW under axial load; the structure has a higher energy absorption capacity and a smoother energy absorption process when the fiber lay-up angle is [0°/90°]ns and [45°]ns; the energy absorption capacity of CFRP-FA-FW is significantly improved by increasing the thickness of the carbon fiber lay-up, and the procedure is also more efficient.

Nonlinear low-velocity impact analysis of sandwich plates with titanium face sheets and porous aluminum core reinforced by GPLs

This study examines the nonlinear dynamic response of sandwich plates under low-velocity impacts (LVIs), which consist of a porous aluminum foam core with functionally graded (FG) graphene platelets (GPLs) reinforcement and two titanium alloy face sheets. The finite element method is employed to perform the numerical simulations and the Hertz contact theory is used to model the impact behavior. The generic Halpin-Tsai model, which incorporates the porosity effect, is adopted to estimate the mechanical properties of core made of the FG-GPLRC, based on the experimental data of the closed-cell aluminum alloy foam. The simulation results reveal that the FG-X configuration has the highest impact resistance, and that the addition of GPLs improves the impact performance. Moreover, a thicker core can reduce both the first contact time and the vibration period of plates, while a looser boundary condition can prolong the vibration time after the first impact. Additionally, a higher impactor velocity, mass and radius lead to a higher deflection and contact force. The oblique impact decreases the impact energy. This work provides a lighter and stiffer design for structure engineers when components suffer low-velocity impact.

Modeling and Simulation of a High-Performance Magnetic Biosensor for Biomedical Sensing

The current magnetic-based biosensor technologies are expensive and intricate, making them unsuitable for meeting the requirements of point-of-care medical diagnosis. This research introduces a straightforward magnetic biosensor architecture that includes an L-shaped ferromagnetic core with UL dimensions. The design involves an air gap being replaced with highly porous aluminum or copper foam, offering a potentially cost-effective and uncomplicated solution for point-of-care diagnosis based on the magnetic field effect. The foam serves as a medium for hosting biological samples, such as proteins and DNA, which are labeled with high-permeability ferromagnetic nanoparticles. The biosensor operates by detecting labeled biological molecules through magnetic field interactions. The electrical parameters of the system underwent methodical optimization to enhance overall performance. The investigation delved into the influence of various materials on the magnetic properties of the air gap. It also examined the relationships between permeability, output-induced voltage, input voltage, and input frequency. The findings reveal that utilizing materials with elevated magnetic permeability, such as Magnetite (Fe3 O4 ) or Cobalt ferrite (CoFe2 O4 ) ferrofluids, significantly enhances the biosensor's performance by optimizing magnetic coupling between primary and secondary windings. This innovative magnetic biosensor exhibits potential applications in diverse fields, including molecular biology and medical diagnostics. The study contributes valuable insights into the design and optimization of magnetic biosensors, offering opportunities for heightened sensitivity and selectivity in the detection of ferromagnetic nanoparticles labeled biomolecules such as DNA or proteins.

Strengthening mechanism of porous aluminum foam by micro-arc discharge

Even with their wide usage, porous metal foams (PMFs) are limited by their poor mechanical strength owing to their inherent porous structures. This study employed a combination of vacuum sintering and microarc oxidation (MAO) to enhance the mechanical properties and corrosion resistance of Al foam while maintaining its low density. Tribological tests and microstructural analysis demonstrated the stable friction coefficients and excellent wear resistance of the MAO-treated PMFs. Further, the microarc discharge strengthening mechanism was explained, and a physical model was proposed. Finally, this approach produced wear-resistant porous Al foams, offering a promising solution to overcome the limitations of PMFs.

Modeling and Free Vibration Analysis of Variable Stiffness System for Sandwich Conical Shell Structures with Variable Thickness

This paper presents modeling and free vibration analysis of variable stiffness system for the truncated sandwich conical shell made of porous aluminum foam core with variable thickness and carbon fiber face sheets under the simply supported boundary condition. The thickness of the core layer varies along the longitudinal direction. Five different types of porosity distribution of the aluminum foam core, which contains Type-X, Type-O, Type-U, Type-V and Type-[Formula: see text] along the direction of thickness, are considered. Considering the effect of thermal environment, we derive the nonlinear dynamic equations based on first-order shear deformation theory and Hamilton’s principle, and obtain the natural frequencies of the system by employing the Galerkin method. The comparison and validation are conducted by contrast with the determined results of the literature. The influences of porosity distribution pattern, porosity coefficient, the total number of layers, temperature increment, semi-vertex angle, the exponent of thickness function, the minimum radius-thickness and length-thickness ratio of the core layer on the natural frequencies, modal and mode shapes are studied comprehensively.

Effect of processing parameters and heat treatment techniques on foaming properties of aluminium foam developed by friction stir processing route

In the present research friction stir processing has been used to make the precursors. The substrate contains the foamable mixture in a pre-drilled hole and the processing has been done in the centre line of the hole. The developed precursors are then treated by two heating methods, i.e. furnace and microwave heating to produce foam. The effect of different process parameters like the number of friction stir processing passes, volume and composition of foamable mixture, and heat treatment techniques have been investigated. The porous aluminium foam has been found with pore size in the range of 0.24–1.35 mm with a proportion of pores between 41% and 56% with microwave heating, while in case of furnace heating, the pore size is in the range of 0.22–1.49 mm with proportion of pores in between 41% and 61%. Also, the results show that the foam developed in microwave heating is much faster than that of furnace heating.

Sustainable Production of Powder Metallurgy Aluminum Foams Sintered by Concentrated Solar Energy

Porous aluminum foams were successfully fabricated following the space-holder powder metallurgy method with a solar sintering stage. Al foams with porosities of 50, 60, and 70 vol.% were sintered in a low-cost Fresnel lens. Green parts were prepared using aluminum powder as the main metallic material and saccharose as a soluble space-holder. The dissolution stage was designed for each foam and required longer periods of time, between 8 and 32 h, as the design porosity increased. Brown parts were fully sintered by concentrated solar energy at a lower temperature (500 °C) and for shorter times (12–20 min) than those required by conventional sintering techniques (640 °C, ~9 h). The evaluation of density and the characterization of pore size and distribution in the sintered foams was carried out. All obtained foams were stable and presented a homogeneously distributed porosity, very close to the design porosity, with differences lower than 2.1 vol.%, and with approximately half being characterized as open porosity. Moreover, the solar sintered foams presented a high quality, and similar or even greater mechanical properties (such as compressive strength and impact energy absorption) than those achieved by conventional techniques. Foams with 50 vol.% of porosity exhibited the best mechanical behavior, in terms of impact-energy absorption (24.42 MJ/m3) and compressive strength (27.4 MPa).

Mechanical behavior of a sandwich plate with aluminum foam core, using an image-based layerwise model

Functionally graded materials are an advanced type of composite materials whose properties’ spatial evolution can be designed through the definition of the spatial distribution of the constituent phases’ mixture. This feature is particularly important if specific non-homogeneous properties’ requirements are required without introducing abrupt phases’ transitions, as happens in laminated materials. Porosities’ distributions within these materials, may constitute a design requisite for some applications, such as medical implants, but can also be highly undesirable in other cases such as for aeronautical applications. Regardless the specific situation, its characterization is of high importance to the prediction of the resulting materials’ behavior. This work is focused on the static and free vibrations’ analysis of a sandwich plate with a porous aluminum foam core and outer aluminum skins. The porosities’ distribution is modeled by different fitting functions, based on data obtained from a preliminary image processing stage of X-ray CT image of the sandwich plate’ cross-section. A layerwise approach is considered for subsequent numerical simulations’ purpose, where the sandwich skins’ kinematics are modeled using the first order shear deformation theory, while the core is modeled by a higher order shear deformation theory. Fitting functions’ influence on the plate’ behavior is also assessed.

Enhanced areal specific capacity and energy density of solid-state lithium battery by using porous aluminum foam

High-loading electrode based on aluminum foil is difficult to use in solid-state lithium battery because of its low conductivity, which affects the areal specific capacity and energy density of the battery. In this work, three dimensional through-hole aluminum foam was used as current collectors of high-loading LiNi0.6Co0.2Mn0.2O2 (NCM622) electrodes and for first time applied in solid-state lithium battery. The use of aluminum foam instead of commercial aluminum foil can greatly increase the areal specific capacity, the areal specific capacity was increased from 0.4 mAh/cm2 to 1.3, 1.4, 1.6 mAh/cm2 for different thickness of aluminum foams. At the same time, the energy density of solid-state battery composed of aluminum foam-based electrodes are 2.5~3 times that of aluminum foil-based solid-state battery. The aluminum foam has a significant application prospect as electrode current collector for solid-state batteries.

PCM-Based Energy Storage System with High Power Output Using Open Porous Aluminum Foams

Thermal comfort (heating, ventilation and air conditioning, HVAC) and the energy consumption involved with it can put a strain on the driving range of fully electric vehicles (FEV), especially in certain times of the year as midsummer or winter. In order to reduce the energy consumption of HVAC, improved thermal management and adapted means of energy storage are needed. One part of the solution can be the use of phase change materials (PCM) for storing waste heat. For the specific application, however, a high loading/unloading power rate is required, which is challenging as the PCMs exhibit low heat conductivities. In the presented work, a storage demonstrator system was investigated which is part of an HVAC system of a specific fully electric vehicle. The profile of requirements of the system (power, stored capacity and allowed volume) make a new design of the storage necessary. Two demonstrator units, in which the PCM was combined with aluminum foam, were manufactured and their power output in dependency on the fluid flow of the coolant system was compared. An adapted squeeze casting process with polymer placeholders was used for the production of the aluminium foam. This process results in foams with a specific pore structure and allows the in-situ integration of the heat transfer fluid (HTF) pipes. Both newly developed PCM storage systems satisfy the HVAC system requirements.

Numerical and experimental investigation of high concentration aqueous alumina nanofluids in a two and three channel heat exchanger

Abstract Nanofluids are often able to provide a method to increase the possible heat transfer of a system, with relatively few detrimental factors created by its inclusion. The use of nanofluids and their optimal concentrations has become an area of great interest as of late, with different nanofluid concentrations being key to a systems success or hindrance. The aim of this work is to examine the impact of nanofluid concentration on the possible heat transfer for different heat sink types containing porous media. In this work, both a numerical and experimental investigation into the impact of an aluminum oxide nanofluid on a fluid flow-based system comprised of porous open-cell aluminum foam to examine their impact on the thermal performance of the system was conducted. The porous media implemented in the experimental work was made of a 6061-T6 aluminum with a porosity of 0.91 and a permeability of 2.3869 × 10−7 m2. The experimental work was carried out for a large range of applied heat flux values varying from 3.8328 W cm-2 to 10.3737 W cm−2. The nanofluid examined was also subjected to varying flow rates. The nanofluid concentration was varied from 1% vol and 2% vol Al2O3–water mixture. The nanofluid was suspended in distilled water and mixed using a magnetic mixer. The performance of the work was examined through the Nusselt number to determine the possible thermal enhancement presented by the nanofluid. The use of high concentration (1% vol) nanofluid paired with the use of two different channel designs, both containing porous media resulted in an average thermal enhancement 15% and a maximum enhancement of 24.5% when compared to that of the 2% vol alumina nanofluid.

Experimental study on heat exchange in a compact porous aluminium foam heat exchanger

In this paper the results of experimental study on hydrodynamics and heat transfer during a single-phase coolant flow in a heat exchanger made of porous foam aluminum are presented. The study was carried out on a specially designed and manufactured experimental setup provided with measuring equipment. The setup is capable of testing in a wide range of thermal and hydraulic characteristics and recording the measurement results automatically. The results allowed verification of previously obtained analytical solutions. This made it possible to use them to develop universal methods for calculating specifications of new porous compact heat exchangers used for cooling heat-stressed elements in various devices. The results obtained in this experimental study confirmed the possibility of using porous compact heat exchangers in thermal protection systems with a specific heat release of up to 100 W/cm2.

Formation and characterization of 6063 aluminum metal foam using friction stir processing route

Metal foams have become a prominent research material in the past decade due to their low specific gravity and high energy absorption capacity. Recently a new method of metal foam formation using “Friction Stir Processing”(FSP) as the starting process has been developed. A mixture of blowing agent powder (TiH2) and stabilization agent powder (Al2O3) is used to form a composite through FSP. This composite on heat treatment converts into a porous aluminum or aluminum metal foam, due to the evolution of Hydrogen gas from the blowing agent. This method if developed properly may lead to the cost effective technique of the aluminum metal foam formation. In this study, closed cell aluminum 6063 metal foam has been developed by using FSP. The porosity of around 60% was obtained. An attempt has been made to analyze the process critically by using various characterization techniques such as SEM and EDS.

Inhibition effect and mechanism of inorganic-organic hybrid additives on three-dimension porous aluminum foam in alkaline Al-air battery

The main barrier preventing the commercial application of alkaline aluminum-air battery is the severe self-corrosion of Al anode. Herein, three kinds of novel inorganic-organic hybrid corrosion inhibitors are constructed, which containing ZnO and organic acids (acetic acid, citric acid and EDTA). Electrochemical tests demonstrate that the combination of ZnO and organic acid effectively suppresses the self-corrosion of Al foam anode in alkaline solution. Among them, the Al-air battery exhibits a high voltage platform (1.13 V), a high specific capacity (1902 mA h g−1) and a high anode utilization (58.23%) within 0.3 M ZnO+0.03 M citric acid hybrid inhibitors system. Surface analyses confirm that the organic acid greatly boosts the formation of uniform and dense Zn film on Al surface. A combined experimental research and theory computation reveal that the corrosion inhibition mechanism of ZnO + organic acid hybrid system is: the phase-forming corrosion inhibitor (ZnO) deposit on the Al surface to form Zn protective film and cover the active sites of hydrogen evolution; the active sites of organic acids are the O atoms of carbonyl groups, which adsorbing on the surface of Zn protective film and Al foam, thereby forming the composite protective films of RCOO-Al and RCOO-Zn.

Novel Flow Field for Proton Exchange Membrane Fuel Cells Made from 72%-Porous Aluminum Foam

Proton Exchange Membrane fuel cells (PEMFC) has emerged as the most widely-used type among fuel cells, due to various advantages. Bipolar plates play a major role in the performance of PEMFC. Flow fields in the bipolar plates distribute fuel and oxidant over the reactive sites of the membrane electrode assembly. Bipolar plates are typically graphite with parallel or serpentine channels as flow fields. Graphite is heavy and has fabrication inaccuracy; it is also costly and brittle. In this paper, open-cell aluminium foam is experimentally investigated as a flow field for a new bipolar plate design made from solid aluminium. The performance of the conventional bipolar plate/flow field was directly compared to that of the aluminium-foam novel design at the same operational conditions. Results show that the cell current, voltage and power density were improved. As importantly, the conversion efficiency was higher for the aluminium-foam design, and the fuel consumption was reduced.

Development of aluminum metal foam using blowing agent

This paper describes the complete manufacturing process for production of the aluminium foam with its achieved important physical properties and its uses in various industries. The production process of aluminum metallic foam includes high purity molten aluminium in which a small amount of calcium carbonate powder is continuously faded and stirred thoroughly. The decomposition of calcium carbonate release gases, which are entrapped in high viscous mixture of the molten aluminium and calcium residues and create low density porous aluminium foam as shown in figure no. 7 and figure no. 8. The aluminum foam is collected and cooled in the mold. Afterward foam is removed from the mold and cut to the desired sizes. The foam with low density 848 kg/m3 is obtained and density of which is 0.342 times of pure aluminum.

Cumulative effects of using pin fin heat sink and porous metal foam on thermal management of lithium-ion batteries

Three-dimensional transient thermal analysis of an air-cooled module was carried out to investigate cumulative effects of using pin fin heat sink and porous metal foam on thermal management of a Li-ion (lithium-ion) battery pack. Five different cases were designed as Case 1: flow channel without any pin fin or porous metal foam insertion, Case 2: flow channel with aluminum pin fins, Case 3: flow channel with porous aluminum foam pin fins, Case 4: fully inserted flow channel with porous aluminum foam, and Case 5: fully inserted flow channel with porous aluminum foam and aluminum pin fins. The effects of porous aluminum insertions, pin fin types, air flow inlet temperature, and air flow inlet velocity on the temperature uniformity and maximum temperature inside the battery pack were systematically investigated. The results showed that using pin fin heat sink (Case 2) is appropriate only for low air flow velocities. In addition, the use of porous aluminum pin fins or embedding porous aluminum foam inside the air flow channel (Cases 3 and 4) are not beneficial for thermal management improvement. The combination of aluminum pin fins and porous aluminum foam insertion inside the air flow channel (Case 5) is a proper option that improves both temperature reduction and temperature uniformity inside the battery cell.

Comparison and Analysis of Heat Transfer in Aluminum Foam Using Local Thermal Equilibrium or Nonequilibrium Model

Aluminum foams are favorable in modern thermal engineering applications because of the high thermal conductivity and the large specific surface area. The present study aims to investigate an application of porous aluminum foam by using the local thermal equilibrium (LTE) and local thermal nonequilibrium (LTNE) heat transfer models. Three-dimensional simulations of laminar flow (porous foam zone), turbulent flow (open zone), and heat transfer are performed by a computational fluid dynamics approach. In addition, the Forchheimer extended Darcy's law is employed to evaluate the fluid characteristics. By comparing and analyzing the average and local Nusselt numbers, it is found that the LTNE and LTE models can reach the same Nusselt numbers inside the aluminum foam when the air velocity is high, meaning that the aluminum foam is in a thermal equilibrium state. Besides, a high interfacial heat transfer coefficient is required for the aluminum foam to reach a thermal equilibrium state as the height of the aluminum foam is reduced. This study suggests that the LTE model can be applied to predict the thermal performance at high fluid velocities or for the case with a large height.

Short-aramid-fiber toughening of epoxy adhesive joint between carbon fiber composites and metal substrates with different surface morphology

Carbon-fiber epoxy composites were bonded to four different types of aluminum substrates with different surface roughness and finish. The four aluminum substrates considered in this study have the following surface conditions: two solid aluminum substrates polished with two different grades of sandpapers, and two porous aluminum foams with two different as-received surface conditions, one with a patterned surface finish and one with rough pore structures. Moreover, the thin epoxy adhesive joints between the carbon-fiber face sheets and aluminum substrates were reinforced by adding short aramid fibers. During the fabrication process of the hybrid laminar, sparsely-distributed short aramid fibers were inserted between the fiber-metal interface to promote bridged fibers for tougher and stronger adhesive bonding, while at the same time to minimize any significant change in the thickness of the adhesive joint. Measurements of the critical energy release rate showed that the toughening effects of the low-density short aramid fibers were influenced by the metal-substrate surface roughness and finish. Further comparison indicated that the interfacial fracture toughness of aramid-fiber interleave adhesive joints increased via increase of surface roughness of metal substrates. The surface-roughness effect of metal substrate mainly depends on whether the free fiber ends of the short aramid fibers were pressed and embedded into the surface cavities of aluminum substrates according to scanning electron microscopy observations. The results indicated that the properties and performances of aramid-fiber interleaved adhesive joints between the carbon-fiber face sheets and aluminum substrates could be improved by surface treatments on the aluminum substrates to achieve appropriately surface roughness.