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This paper presents an experimental study on heat exchangers based on fins, open-cell metal foam and thermal interface material (TIM). Experiments were conducted on the copper foam of 40 PPI with 1 mm thickness plate fins and two commercial TIMs (pad types) with thermal conductivities of 5 and 12 W/mK. Different compact fin copper foam heat exchanger configurations were tested at varying Reynolds numbers. The heat exchanger and a test rig were designed and fabricated in-house. The results show that the fin copper foam heat exchanger with TIM 12.8 W/mK thermal conductivity has the maximum Nusselt number, 923.66, at a Reynolds number of 25,677. It has achieved the highest heat transfer performance among other configurations of heat exchangers. The fin copper foam heat exchanger with the same TIM has the maximum pressure drop at the same Reynolds number, which was 261.96 Pa, due to the limitation of the amount of air that can pass through the heat exchanger due to fins and foams. This study shows that joining metal foam and fin with TIM in a heat exchanger can increase the surface area between mating parts and thus increase heat transfer. It also provides insights into an alternative means of joining metal foams with other metals (or a base plate) to develop high-performance heat exchangers. [ABSTRACT FROM AUTHOR]

In casting process porosity is consider as defect in the product but in metal foam structure pores and porosity are consider as most desirable property for impact absorption, vibration absorption and low thermal conductivity. In solar parabolic trough collector metal foam pipe use more thermal efficiency compared to flat hollow pipe. In this article manufacturing techniques to make metal foams are discussed and advantages of solid space holder technique over other existing techniques is also mentioned. Minimum pore size and orientation of pores are the main parameters to make a better metal foam structure and these parameters are biggest challenge to achieve by researchers and industries. [ABSTRACT FROM AUTHOR]

A FinFET (Fin Field Effect Transistor) is a non-planar transistor. It has a faster-switching speed, lower power consumption, and static leakage current than CMOSs (Complementary Metal Oxide Semiconductors), which are planar transistors. In the FinFET logic ICs (Integrated Circuits) fabrication process, open defects may occur at interconnects between gates inside them. Open metals may cause defects. Since the FinFET ICs may be operated in high-speed time, the defects are more difficult to analyze in time domain signals. There is a method of FFT (Fast Fourier Transform) computing signals converted from the time domain signals into frequency domain signals. Then, the derived frequency signals will be expressed into the function of the Fourier series. In this paper, the FFT analysis is proposed to detect the defects inside the ICs. The logic ICs of Buffer, AND, and OR are designed by a SPICE (Simulation Program with Integrated Circuit Emphasis) netlist library distributed by Nexperia Co. Ltd. Then, the defects are inserted inside the designed ICs and simulated using LTspice created by Analog Devices Inc. Simulation results show that magnitude signals of defective logic ICs in the Fourier series will decrease linearly with increasing sizes of the defects. [ABSTRACT FROM AUTHOR]

Magnesium alloys like one of the bioabsorbable implant materials expected to help heal tissue without implant residues, therefore are no need to take the implant for a second surgery. One of the expected performances of metal implants is its ability to support cancellous bone growth, namely porous bone that encloses large spaces and has a spongy nature or appearance, therefore metallic magnesium foams are used in bone implants to approach the natural structure of bones. This study aims to evaluate the effect of dolomite (CaMg(CO3)2) size as a foaming agent to produce porosity on Mg-6Zn alloy. Powder metallurgy is used to produce metallic magnesium foams. Magnesium powder 0.06-0.3 mm granulometry mixed with zinc powder <63 µm granulometry and dolomite powder with varying sizes 20, 25, and 30 mesh. The mixed powder was compacted and sintered at varying temperatures of 650, 675, and 700°C. The smallest porosity is found in the Mg6Zn10CaMg(CO3)2 alloy with a #25 mesh foaming size and a sintering temperature of 650°C, or 10.77%. Meanwhile, the highest porosity was found in the mesh alloy Mg-6Zn-10CaMg(CO3)2 #20 with a sintered temperature of 700°C, or 53.26%. These results indicate that the higher the sintering temperature in the alloy, the greater the percentage of pores formed and the smaller the density value produced in the alloy. [ABSTRACT FROM AUTHOR]

Metal foam as a wick structure in heat pipe applications is analyzed in terms of its capillary and thermal properties to determine the perspectives and challenges ahead. The surface coating of metal foam with a hydrophobic layer was analyzed for its effect on the overall capillarity in order to determine the optimal metal foam as a wick structure in the heat pipe. The hydrophobic coating is applied by a simple spray technique to the entire surface of the metal foam with repetition. Metal foam without a hydrophobic layer has stable capillarity properties among other samples, this indicates that the hydrophobic layer can inhibit the ferro fluid flow rate in the metal foam pore network as a whole as a result of the interaction between the metal foam phases and the hydrophobic layer. Metal foam 15 PPI without hydrophobic coating has an even and stable heat distribution, high conductivity and low resistivity which is suitable for application as a wick structure in heat pipes. [ABSTRACT FROM AUTHOR]

In this study, the thermal and dynamic performance of a cross-flow heat exchanger was numerically investigated by using the Darcy-Brinkman-Forchheimer and Navier-Stokes equations. The copper foam is embedded around the tube surface to increase the heat transfer rate. The open cell copper foam was treated as a porous medium so that the Local Thermal Equilibrium (LTE) model was used in this study to find the temperature distribution. The copper foam has a pore density of 40 PPI, and a porosity of 0.93. The numerical solution used the air as a working fluid with a Reynolds number (Re) of 200 to 850. The ratio of copper foam thickness to tube diameter (L/d) varies from 2 to 20, while the ratio of tube pitch to tube diameter (H/d) varies from 2 to 20. The result showed the friction factor increased as (L/d) increased, and the highest value of the Colburn factor (j) can be obtained when (L/d) equals 2. H/r increasing leads to an increase in the friction factor and Colburn factor (j). The optimal height of metallic foam can be evaluated by using the area goodness parameter (AG), which is at H/r equal to 3 in.the current study. [ABSTRACT FROM AUTHOR]

Hydrogen production for low greenhouse gas emissions attracts great interest of several research group worldwide. Even though current scientific research has made a lot of progress on the hydrogen field, several technological locks related to heat and mass transfer limitations in steam reforming processes remain to be overcome. This study focuses on numerical analysis of steam methane reforming reaction combined with experimental measurements of Nickel-based Metal Foam (Ni-MF) permeability coefficients. Two configurations of micro-planar-cell reactor were investigated. The first one consists of a 2D plane micro reactor in which catalyst is impregnated in the central axis. The second micro reactor is equipped by an inert metal foam. Numerical resolution of transport equations was realized with a homemade FORTRAN-based code to explore the thermal and mass transfer during the SMR process. To model the presence of Ni-MF into the reactor and for better assessment of the Ni-MF contribution, permeability coefficients (Darcy and Forchheimer coefficients) required as input data for the numerical analysis were measured experimentally. Comparison has shown that the insertion of Ni-MF achieves a considerable enhancement in terms of heat transfer, methane conversion and hydrogen yield. [ABSTRACT FROM AUTHOR]

The X-ray radiation absorption from aluminum metal foam was conducted at the various of thickness from 5-40 mm, with the cavity diameters of 2, 3, and 4 mm, and at the energy of 0.1; 0.662 and 1 MeV. The modeling was carried out using the Monte Carlo N-Particle eXtended (MCNPX) program. Calculation of the radiation absorption from the modeling results shows that the performance of aluminum metal foam is close to pure lead plates. This means that aluminum metal foam is expected to be used as radiation shielding for replacing pure lead material. [ABSTRACT FROM AUTHOR]

As a material commonly used as a shield for X-ray radiation, lead has a major weakness, it is a heavy metal that can be toxic to the environment. Therefore, it is necessary to innovate X-ray radiation shielding materials that are better than lead, one of which is tungsten which is also proven to be able to function as a radiation shielding. However, radiation shieldings, generally in the form of plates, have weaknesses, including being heavier and uneconomical. Therefore, metal foam technology has been developed, which is expected to produce X-ray radiation shielding with a lower density than the plate form but almost the same performance as the plate form. In this study, simulation has been carried out to calculate the X-ray transmission through tungsten and lead in the form of plate and metal foam for thickness 5-40 mm, diameter 0.5; 1; 1.5; 2, 3, and 4 mm at energy 0.1; 0.662; and 1 MeV. The modeling of plate and foam metal was carried out using the Monte Carlo N-Particle version 6 (MCNP6) code. The result of X-ray transmission calculation on the thickness of 0.5 to 4 cm, diameter 0.5; 1; 1.5; 2, 3, and 4 mm at the energy 0.1; 0.662; and 1 MeV shows that the performance of tungsten (W) both in the form of plate and metal foam is better than lead material, while in the form of metal foam, the ability of tungsten (W) is close to that of lead (Pb) plate when the diameter of tungsten (W) are 1.5 to 2 mm. From the result of the analysis, it can be concluded that technology of tungsten metal foam can be used as an effective and environmentally friendly X-ray radiation shielding. [ABSTRACT FROM AUTHOR]

The article examines main opportunities in developing space metallurgy; it is noted that metallurgy includes processes of cleaning metals from unwanted impurities, production of metals and alloys, metal thermal treatment, casting, coating the product surfaces, etc. Most of these processes include phase transitions to liquid or gaseous states, where the influence of mass forces magnitude on composition and structure of the final material could be significant. Therefore, transferring metallurgical processes into space opens up fundamentally new possibilities in production of materials with improved characteristics, as well as of those materials that could not be obtained on Earth. Unique crystals and alloys could be produced in space. The article reveals goals of the space metallurgy development, considers the unique conditions of outer space, explores the promising areas of space metallurgy, which includes production of rare ultra-strong crystals and alloys, development of processes for assembling, welding, soldering and repairing metal structures in orbit, production of composite materials, nanostructured composite powders, foam metals. A number of measures is proposed in developing the space industry, special attention is paid to ergonomics of new materials, which should be lightweight and reduce the weight of aerospace vehicles by more than a half. [ABSTRACT FROM AUTHOR]

By using convective cooling, the open-cell metal foam has been investigated as a lightweight heat exchanger. Metal foam is categorized as cellular structured with open-cell randomly oriented and uniform shape and size. In the last decade, many authors had been discussing the use of open-cell metal foam for an electronic cooling system. So this paper explores the effect of air mass flow rate against heat transfer coefficient for varying porosity and varying pore density. Eight specimens of varying porosity form (0.4 to 0.6) and (PPI 10, 20, 40) are studied against varying the mass flow rate of (0.027 to 0.088 kg/s). The result of the analysis shows that the heat transfer coefficient increases as the air mass rate increases and porosity decreases. Also, the behavior of foam efficiency and Reynolds number against air mass flow rate are studied. Analysis shows that foam with a porosity of 40% has a heat transfer coefficient of 1.2 times the foam having a porosity of 60%. As a whole, this paper adds to our understanding of the behavior of the heat transfer coefficient in open-cell metal foam as a function of mass flow rate. [ABSTRACT FROM AUTHOR]

Metal foams are advanced materials with unique and excellent properties. One promising method to produce metal foams is the metal injection moulding-powder space holder (MIM-PSH) method. In this study, experimental work has been performed to identify the feasibility and effect of a novel space holder, namely, glycine, on the MIM-PSH process. Materials used were water atomised stainless steel powder, glycine powder and the multi-component binder consisting of paraffin wax and polythene. Compression specimens were injection moulded, debound and sintered. The porosity, pore size distribution and microstructure characteristics of the samples were characterised. The results show that the glycine is a suitable space holder for the MIM-PSH process. Samples with the porosities in the range of 42.4% to 52.1% were successfully produced. The total porosities of the samples were directly proportional to the glycine content. Marcopores (100 µm) and micropores (1–10 µm) were observed in the samples. The microstructure and pore size of the samples are found to have a potential application in certain functional applications such as filters, fluid separation and biomedical implants. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of Aluminium alloy low carbon (Al-LC) steel composite foam in the joint dynamic property of Redundant Delta Parallel Robot (RDPR) by adopting multibody system methodology. The customized composite foam material is used as design material for delta robot components during the Solidworks CAD model development, which is incorporated with Simscape Multibody simulation tool. The dynamic property, torque exerted at robot joints are identified by means of Simscape Multibody simulation of system blocks scheme of delta. The results of Simscape simulation revealed the pertinence of applying Al-LC steel composite foam in designing redundant delta robot based on the dynamic property observations. [ABSTRACT FROM AUTHOR]

Within the framework of import substitution, obtaining a new modern type of foamed metal is strategically important, which in the future can widely expand the possibilities of its use. Foreign experience of commercial proposals for the production of foamed metals is currently represented mainly from products made on the basis of aluminum or nickel powders with the addition of foaming agents in the form of titanium hydride, but it is an expensive component of foamed metals. To obtain new types of porous metals, it is essential to find new types of foaming agents, which should be less expensive in terms of cost and ease of production. The mechanisms and technological scheme of one of the main types of obtaining a porous structure of aluminum are considered. A study of the process of obtaining a new type of foam metal material with new types of foaming agents obtained from the waste of production in comparison with other types of porous metals and their foaming agents, such as titanium hydride, various types of carbonates, etc. [ABSTRACT FROM AUTHOR]

Magnesium alloys were known to have a rapid corrosion rate, leading to material disintegration and eventually implant failure. The study aims to evaluate porous Mg-Ca-Zn alloys as biodegradable implants. The in vitro biocorrosion behavior of magnesium alloys metallic foam Mg-1Ca-3Zn was manufactured via powder metallurgy with a different variation TiH2 used as a foaming agent and different heat treatment routes, i.e., preheated at 450 °C and without preheated followed by sintering at 550 °C for 3 hours. The corrosion behavior was studied through the immersion test and electrochemical test in Hank's solutions. Immersion test results indicated that samples with 3 % TiH2 have the highest pH increment during the test leading to pronounced spallation. After exposure, the SEM results of the studied alloys revealed microcracks as well as volcano-like structure formation. The corresponding EDX measurement revealed that the studied alloys with TiH2 contents :S 1.5 wt.% show some Ca and P traces instead of Mg and O as corrosion products. Whereas samples with 3% TiH2 predominantly contained only Mg and O. Potentiodynamic polarization experiments conducted at 37 °C and pH 7.4 indicated the increased biodegradation rates resulted from the porous structure preheated samples. The results showed that preheating at 450 °C before sintering at 550 °C impairs the corrosion resistance due to the pore formation. The addition of 3 % TiH2 leads to corrosion layer formation consisting of predominantly Mg(OH)2. [ABSTRACT FROM AUTHOR]

A cellular structure made up of solid metal is significantly termed as Metal Foam. It consists of gas-filled pores in large volumes. These gas-filled pores are sometimes closely packed termed to be closed-cell foam and sometimes it is a network with interconnected termed to be open cell foam. The closed-cell foam is mainly contributed to weight saving and impact-absorbing structural application in automotive vehicles. The open-cell foam is contributed to vibration and sound absorption and catalysis to withstand high temperature for heat exchanger. The attractive method for fabricating metallic foam production is Powder metallurgy because it allows for the processing of a wide range of integral sandwich structures. This work explains the fabrication of Magnesium reinforced with Aluminum, copper, and zinc with yttrium metal foam with titanium hydride as foaming agents and calcium stearate as a binding agent. The pellets are prepared by the powder metallurgy method at the dimension of 20mm diameter and 16mm thickness. The sintered samples are tested for the characteristics of corrosion by using a salt spray test. The sample of the first series which has the composition of Mg-70% Al-30% gave the best result in corrosion resistance results in mpy unit but in mm/yr. samples 1.3 and 2.1 which has the composition of Mg-70% Al-30% and Mg-50% Al-25% Cu-25% respectively gave the best corrosion resistance results in mm/yr. [ABSTRACT FROM AUTHOR]

This work explains about the fabrication of Magnesium reinforced with aluminum, copper, zinc with yttrium metal foam with titanium hydride as foaming agents and calcium stearate as binding agent. The pellets are prepared by powder metallurgy method at a dimension of 20mm diameter and16mm thickness. The sintered samples are tested for mechanical characteristics. The results of mechanical characteristics for the composition Mg-Al-Cu-Re has the highest load bearing capacity of 52.24kN. The composition Mg-Al-Cu-Re has the highest Compressive strength capability of 163.82Mpa. Hardness value with the composition Mg-Al-Re has the highest hardness value of 204.88VHN. Energy absorption for the composition Mg-Al-Cu-Zn-Re has the highest energy absorption characteristics of 186.944KJ because energy absorption is directly proportional to the porosity of the sample. This work explains about the fabrication of Magnesium as parent metal reinforced with aluminum, copper, zinc with yttrium metal foam with titanium hydride as foaming agents and calcium stearate as binding agent. The pellets are prepared by powder metallurgy method at a dimension of 20mm diameter and 16mm thickness. The sintered samples are tested for their mechanical characteristics by compression and hardness tests. The results of mechanical characteristics for load vs displacement with the composition Mg-Al-Cu-Re has the highest load bearing capacity of 52.24kN. Stress vs strain the composition Mg-Al-Cu-Re has the highest stress bearing capability of 163.82Mpa. Hardness value with the composition Mg-Al-Re has the highest hardness value of 204.88VHN. Energy absorption for the composition Mg-Al-Cu-Zn-Re has the highest energy absorption characteristics of 186.944KJ because energy absorption is directly proportional to the porosity of the sample [ABSTRACT FROM AUTHOR]

Tungsten disulfide, owing to its high theoretical specific capacitance is one of the most studied and promising candidates for electrochemical energy storage applications among various layered materials. Herein, we have fabricated WS2 thin films on silicon substrates by using reactive DC magnetron sputtering technique with metallic tungsten target and H2S as sulfur source at room temperature (Ar:H2S 2:1). For electrochemical application, the electrodes have been prepared in-situ using copper foam as current collector. The in-situ growth allows the films to form actively structured electrodes as well as provide an opportunity to study the morphological effect of electrodes on electrochemical performance. The morphological results depicted the growth of grainy WS2 thin films on current collector with an average roughness of 2.7 nm. Further, we have performed detailed electrochemical analysis and studied the supercapacitive properties of tungsten disulfide. We found the electric double layer capacitance of WS2 thin films to be 2.42 mF/cm² with linear charge discharge characteristics. This high areal capacitance of WS2 thin films may be attributed to the contribution of metallic foam current collector which reduces the global equivalent series resistance of electrode-electrolyte system. Additionally, copper foam functions as a mechanical backbone and improves the charge carrier transport across the electrode. [ABSTRACT FROM AUTHOR]

Graphene is a carbon material that presents special properties. Usually, graphene is obtained by chemical or thermal reduction of graphene oxide. The graphene grown by chemical vapor deposition on metal foam substrates lead to obtaining of graphene structures with ultralow density, high surface area, high mechanical strength, electrical conductivity, and optical transparency, suitable for different applications. In this paper, we synthesized graphene by using nickel and copper foams as substrate in a CVD process with methane as carbon source. Different deposition times were used. The graphene grown on metal foams were investigated by SEM, XRD and Raman spectroscopy in order to make a comparative study. [ABSTRACT FROM AUTHOR]

In the present work a metal foam heat sink is presented, which is suitable for hybrid solar panels. The heat sink is designed to be placed in contact with a layer of photovoltaic cells, removing from them the heat resulting from the solar radiation. It is composed of an aluminum box containing an aluminum open-cell foam, through which a water flow is forced. Some preliminary measurements are presented. In particular the pressure drops between the inlet and outlet water plena and the global heat transfer effectiveness are shown under different conditions. [ABSTRACT FROM AUTHOR]

Metal foams have porosities larger than ninety percent would be ready by a unique metallurgy route employing a chemical compound vehicles. Coarse metal powder Al powder with sugar were tested. The powders were homogenized then press at 4 (ton), with 3 additives of sugar and pure Al (30%,40%,70% of sugar, and pure Al), then sintered at 600 °c. Upon transmutation to get foams, three physical properties tested Such as Apperant density, L.M, and L.SH. Apperant density is decreasing with increasing of sugare, while in L.M, and L.SH. are increasingin their values with sugar additives. The influence of foams factor on porosity and the physical tested have been shown these foam sample has applications within the of filtering application, biomaterials, and others. [ABSTRACT FROM AUTHOR]

The aim of the present activity was the manufacturing of enhanced closed-cell aluminum foam based samples for industrial applications such as security systems in the automotive field (e.g., anti-intrusion bars); as reinforcement, that also constitutes a flexible die, a stainless steel wire mesh was considered. The Powder Compact Melting technique was used for producing cylindrical samples, starting from a commercial foam precursor and replacing the conventional dies by the wire mesh, the last with the additional effect of foam reinforcement. Quasi-static compression and three-point bending tests were performed to determine the mechanical behavior of these reinforced and lightweight samples, in order to compare their properties with the ones of plain foam samples. Finally, a component with a complex geometry was manufactured, aiming to evaluate the chance to use the proposed flexible dies as metal foam reinforcements in many instances. [ABSTRACT FROM AUTHOR]

The role of blowing agent in the manufacture of porous metal alloys is very important to produce the desired pore. The thermal stability and speed of foam formation have an effect on the resulting pore structure. In porous metal alloys, uniformity of size and pore deployment are the main determinants of the resulting alloys. The coating process of calcium carbonate (CaCO3) has been done using Sodium trisilicate solution by sol-gel method. Foaming agent was pretreated by coating SiO2 passive layer on the surface of CaCO3. This coating aims to produce a more stable blowing agent so that the foaming process can produce a more uniform pore size. The microstructure of the SiO2 passive was observed using Scanning Electron Microscope (SEM) equipped by Energy Dispersive X-Ray Spectrometer (EDS) mapping. The results showed coating CaCO3 using sodium trisilicate was successfully done creating a passive layer of SiO2 on the surface of CaCO3. By the coating process, the thermal stability of coated CaCO3 increased compared to uncoated CaCO3. [ABSTRACT FROM AUTHOR]

Metal foams are finding an increasing range of applications by their lightweight structure and physical, chemical and mechanical properties. Foams can be used to fill closed moulds for manufacturing structural foam parts of complex shape [1]; foam filled structures are expected to provide good mechanical properties and energy absorption capabilities. The complexity of the foaming process and the number of parameters to simultaneously control, demand a preliminary and hugely wide experimental activity to manufacture foamed components with a good quality. That is why there are many efforts to improve the structure of foams, in order to obtain a product with good properties. The problem is that even for seemingly identical foaming conditions, the effective foaming can vary significantly from one foaming trial to another. The variation of the foams often is related by structural imperfections, joining region (foam-foam or foam-wall mold) or difficulties in achieving a complete filling of the mould. That is, in a closed mold, the result of the mold filling and its structure or defects are not known a priori and can eventually vary significantly. These defects can cause a drastic deterioration of the mechanical properties [2] and lead to a low performance in its application. This work proposes the use of advanced nondestructive techniques for evaluating the foam distribution after filling the mold to improve the manufacturing process. To achieved this purpose ultrasonic technique (UT) and cone beam computed tomography (CT) were applied on plate and structures of different thicknesses filled with foam of different porosity. UT was carried out on transmission mode with low frequency air-coupled transducers [3], in focused and unfocused configurations. [ABSTRACT FROM AUTHOR]

In this work, the fabrication process and the mechanical characterization of hybrid closed-cell aluminum foam/bio-composite samples were presented. The samples were realized starting from aluminum foam cylinders, obtained by a powder compact foaming process of a dense precursor, wrapped with fabrics of hemp fibers, manually impregnated with epoxy resin. Successively, their mechanical properties were determined, with the ones of the single constituents, i.e. foam cylinders and bio-composite tubes, by means of quasi-static tests. The results of the mechanical tests highlight the properties improvement of the hemp fiber reinforced polymer composite tubes with aluminum foam core, compared to the sum of the single constituents. [ABSTRACT FROM AUTHOR]

Aluminium foam is a kind of metal foam material which has large energy absorption capability. The mechanical properties of aluminium foam material in high strain rates could be measured by using SHPB. Numerical simulation is used as the initial step to measure mechanical properties of this material. MAT 163 modified crushable foam used as material model in the SHPB numerical simulation of aluminium foam. Numerical simulation showed a quite close results to experimental data. [ABSTRACT FROM AUTHOR]

According to available literature, it is assumed that outer packaging container, which is usually made of corrugated cardboard, does not influence the mitigation of the impact effects, thus in the designing process of packaging system the outer packaging is skipped. The purpose of this paper is to verify the above assumption, including determination of the influence of the 5-layer cardboard on the properties of structures that consist of that cardboard and polyethylene foam. Verification is performed with the use of the finite element method. To apply this method the dynamic compression curve of cushioning material is required. Therefore in the paper it is also presented the modified method to determine the curve. [ABSTRACT FROM AUTHOR]

Metal foams are interesting materials with many potential applications. They are characterized by a cellular structure, that is the metals or metal alloys foamed include gas voids in the material. Their particular lightweight structure and physical, chemical and mechanical properties make them suitable for a wide range of industrial applications in different sectors. For industrial applications, metal foams offer attractive combinations of low density, high stiffness to weight ratio, good energy absorption and vibration damping capacity that cannot be obtained with other materials. The control of the foaming process and the characterization of the metal foam are important issues in order to obtain a product with good properties and guarantee the quality of a mechanical component. The characterization and control of mechanical components and sandwich panels manufactured with metal foams require the assessment of the defects present in this material, like large pores or imperfections which are responsible of deteriorating the mechanical performance. Therefore, specific methods of non-destructive testing are required, both in the manufacturing process and during the life of the component. In this work, some ultrasonic transmission techniques developed for detection of defects associated with the manufacturing process of aluminum foams are proposed. These techniques were used on plates and structures of different thicknesses and geometries formed with this material. Ultrasonic transmission techniques were carried out both, with low frequency air coupled transducers, and higher frequency transducers, focused and unfocused, by contact and immersion. To validate the results, the ultrasonic images obtained were compared with radiographic images of the foam. [ABSTRACT FROM AUTHOR]

Novel Ni3S2@NiOOH hybrid nanostructures have been synthesized using Ni foam (NF) as support and Ni source through a facile low-temperature sulfurization and following in situ electrochemical oxidation process. The structure and composition of the as-prepared samples were characterized by XRD, XPS and SEM. The uniform film composed of volcanic-like Ni3S2 nanostrucutres covered on the surface of Ni foam after 300 °C sulfurization in H2S/N2 for 1h. The similar film of Ni3S2@NiOOH hybrid nanostructure has been obtained after electrochemical treatment of Ni3S2/NF in 1.0 M KOH (called ET-Ni3S2/NF). The electrocatalytic performances of all the samples for hydrogen evolution reaction (HER) have been investigated. The obtained ET-Ni3S2/NF shows smaller onset potential and Tafel slope than Ni3S2/NF due to the formation of NiOOH nanoplates on the surface of NF. The synergistic effect between Ni3S2 and NiOOH may be responsible for the enhancement of the HER activity. [ABSTRACT FROM AUTHOR]

Mg-Zn-Ca alloy is one of magnesium alloys that has been investigated for its potential in metal foam implant application. In this study, porous Mg-Zn-Ca alloy was prepared by powder metallurgy method, comprising of green compact fabrication and its sintering process. Calcium hydride (CaH2) was added as a foaming agent. The composition of Mg-Zn-Ca alloy was varied (1-30%wt CaH2, and 1 variation with 9%wt Ca addition; while Zn constant) to study the effect of foaming agent and calcium addition on phase formation and structural properties of Porous Mg alloy. Sintering process was done in a tube furnace under argon atmosphere in 520°C for 2 hours. The as-sintered alloys were characterized by scanning electron microscopy (SEM) and also X-Ray diffraction analysis (XRD). Microstructure characterization showed different CaH2 content in the alloy would give different type of pores. There was a tendency of increasing pore size and rough grain along with higher content of CaH2. Further, XRD analysis indicated that sintering process formed a Mg, MgO, CaO, and also intermetallic phases of Mg2Ca and also Ca2Mg6Zn3 phase. [ABSTRACT FROM AUTHOR]

The results of tests on samples of foam concrete with a hardening accelerator are presented. As the setting and hardening accelerators the following chemical additives were used: Universal-P-2 and Asilin 12. All additives were added into the insulating foam concrete mix of brand D 400 in the amount of 0.5% to 1% of cement weight. By using of additives in foam concrete technology - hardening accelerators Asilin 12 and Universal P2 in the amount of 0.5% - and 1.0% by weight of cement foam concrete structure formation is accelerated and increases strength by 60%. For the industrial preparation of foam concrete mix technological regulations are worked out, in which it is recommended to use additives - hardening accelerators Asilin 12 in the amount of 0.5% and Universal P2 - 1% of cement weight. [ABSTRACT FROM AUTHOR]

This paper describes the technology and properties of autoclaved foam concrete taking into account practical experience and laboratory studies. The results of study of raw materials and analysis of structure and properties of foam-concrete before and after autoclave treatment are basic in this work. Experimental studies of structure and properties of foam concrete are carried out according to up-to-date methods and equipment on the base of the shared knowledge centers. Results of experimental studies give a deep understanding of properties of raw materials, possible changes and new formations in inner layers of porous material providing the improvement of constructional and operational properties of autoclaved foam concrete. Principal directions of technology enhancement as well as developing of production of autoclave foam concretes under cold-weather conditions in Russia climate are justified. [ABSTRACT FROM AUTHOR]

Mathematical model for the description of deformation of a porous metal is constructed on the basis of generalized rheological method, taking into account change in the resistance to external loads, when the collapse of pores occurs. Irreversible deformation is described with the help of yield condition, modeling the plastic loss of stability of a porous skeleton. For a homogeneous porous medium the fields of displacements and stresses in the problem of radial expansion of spherical and cylindrical cavities under the action of internal pressure considering the effect of collapse of pores are constructed in closed form. The algorithm of numerical realization of the model of dynamic deformation of metal foams on multiprocessor computer systems of the cluster type is worked out. [ABSTRACT FROM AUTHOR]

Nanoparticle-stabilized CO2 foams have been used for mobility control for CO2 flooding; however, raw nanosilica particles which are hydrophilic in nature tend to develop unstable CO2 foam under certain reservoir conditions. The unstable foam leads to particles aggregation resulting in complete retention while propagating in a long distance, deep into the reservoir. This can be avoided by the application of a particular coating of a specific surfactant, polymer or their combination to the surface of the nanoparticles. The in-situ surface activation of unmodified SiO2 nanoparticles by interaction with mixed surfactant (TX100:SDBS) in aqueous media has been studied with extensive experiments using variable volumetric ratios. The retention of in-situ surface-modified nanoparticles was evaluated by the injection of the dispersion of nanoparticles through a sandpack. The loading of nanoparticles in dispersion was ranging from concentrated (5 wt %) to dilute (0.1 wt %). Effluent nanoparticles concentration histories were measured to determine the retained particles in the sandpack. Little retention (< 10% of particles injected over two pore volumes) was attained for 0.5% SiO2 and volumetric ratio of 2:1 (TX100:SDBS). These results were concluded in terms of surface charges, adsorption isotherm, surface adsorption, and DLVO theory between particles and rock. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid foams based on an alkali alumino-silicate matrix were prepared by using different foaming methods. Initially, the synthesis of an inorganic matrix by using aluminosilicate particles, activated through a sodium silicate solution, was performed at room temperature. Subsequently the viscous paste was foamed by using three different methods. In the first method, gaseous hydrogen produced by the oxidization of Si powder in an alkaline media, was used as blowing agent to generate gas bubbles in the paste. In the second method, the porous structure was generated by mixing the paste with a "meringue" type of foam previously prepared by whipping, under vigorous stirring, a water solution containing vegetal proteins as surfactants. In the third method, a combination of these two methods was employed. The foamed systems were consolidated for 24 hours at 40°C and then characterized by FTIR, X-Ray diffraction, scanning electron microscopy (SEM) and compression tests. Low density foams (~500 Kg/m³) with good cellular structure and mechanical properties were obtained by combining the "meringue" approach with the use of the chemical blowing agent based on Si. [ABSTRACT FROM AUTHOR]

Cryogenic insulation designed to operate at various pressures from one atmosphere to vacuum, with high thermal performance and light weight, is needed for cryogenically fueled space launch vehicles and aircraft. Multilayer insulation (MLI) performs well in a high vacuum, but the required vacuum shell for use in the atmosphere is heavy. Spray-on foam insulation (SOFI) is often used in these systems because of its light weight, but can have a higher heat flux than desired. We report on the continued development of Load Responsive Multilayer Insulation (LRMLI), an advanced thermal insulation system that uses dynamic beam discrete spacers that provide high thermal performance both in atmosphere and vacuum.LRMLI consists of layers of thermal radiation barriers separated and supported by micromolded polymer spacers. The spacers have low thermal conductance, and self-support a thin, lightweight vacuum shell that provides internal high vacuum in the insulation. The dynamic load responsive spacers compress to support the external load of a vacuum shell in one atmosphere, and decompress under reduced atmospheric pressure for lower heat leak. Structural load testing was performed on the spacers with various configurations. LRMLI was installed on a 400 liter tank and boil off testing with liquid nitrogen performed at various chamber pressures from one atmosphere to high vacuum. Testing was also performed with an MLI blanket on the outside of the LRMLI. [ABSTRACT FROM AUTHOR]

The present study explores the possibility of using metal foams for thermal management of fuel cells so that air-cooled fuel cell stacks can be commercialized as replacements for currently-available water-cooled counterparts. Experimental studies have been conducted to examine the heat transfer enhancement from a thin metal foam layer sandwiched between two bipolar plates of a cell. To do this, effects of the key parameters including the free stream velocity and characteristics of metal foam such as porosity, permeability, and form drag coefficient on heat and fluid flow are investigated. The improvements as a result of the application of metal foam layers on fuel cell systems efficiency have been analyzed and discussed. Non-optimized results have shown that to remove the same amount of generated heat, the air-cooled fuel cell systems using aluminum foams require half of the pumping power compared to water-cooled fuel cell systems. [ABSTRACT FROM AUTHOR]

The thermo-physical behavior of open-celled metal foams depends on their microscopic structure. An ideal periodic isotropic structure of tetrakaidecahedron shape i.e. Kelvin cell is studied. We have proposed an analytical model in order to obtain geometrical parameters correctly as they have substantial influence on thermal and hydraulic phenomena, where strut geometry is of prime importance. Various relationships between different geometrical parameters and porosities are presented. Consequently, empirical correlations are proposed to determine permeability and inertia coefficient using Ergun like model for computing pressure drop. [ABSTRACT FROM AUTHOR]

Porous media that are used in convection heat transfer designs include those which have high thermal conductivity, in addition to having large surface area density. Prime examples are metal and graphite foams. Robust and easy-to-follow engineering models for forced convection heat transfer inside such media are indispensable for thermal system design. An analytical solution for fully-developed forced convection heat transfer inside a confined cylindrical isotropic porous medium subjected to constant wall heat flux is presented. The analysis assumes Darcy flow and high Péclet number. The two-equation model for the solid and the fluid is simplified by neglecting the conduction term is the fluid's energy equation. Such assumption is valid for gas flow in highly conductive porous media. The Brinkman-extended Darcy momentum equation solution for the velocity profile is used in the fluid's energy equation. The solid and fluid temperatures are obtained. They decay as the distance from the wall increases in the radial direction. The analytical solution is verified by direct experiment for airflow inside a heated aluminum cylinder filled with aluminum foam with a high porosity and twenty pores per inch. The foam is brazed to the inside surface of tube to minimize thermal contact resistance. Acceptable agreement between the analysis and the experiment is obtained. The solution is of utility for heat transfer designs, and for more complex modeling of the heat transfer phenomenon in porous media. [ABSTRACT FROM AUTHOR]

In this paper, copper and aluminum foams with different porosity, number of pores per inch (PPI) and foam core height, are experimentally studied during air forced convection. The experimental measurements permit to understand how each parameter (i.e. porosity, PPI, material, and foam thickness) affects the heat transfer and fluid flow behavior of the metal foams. The paper presents the experimental heat transfer coefficients, permeability and inertia coefficients; moreover, it reports the normalized mean wall temperature as a function of the pumping power per unit of heat transfer area: two meaningful parameters that allow quantitative comparisons of different enhanced surfaces, which can be considered suitable for electronic thermal management. [ABSTRACT FROM AUTHOR]

On this work, the authors present the development and evaluation of an innovative system able to perform reliable panels of sandwich sheets with metallic foam cores for industrial applications, especially in automotive and aeronautical industries. This work is divided into two parts; in the first part the mathematical model used to describe the behavior of sandwich shells with metal cores form is presented and some numerical examples are presented. In the second part of this work, the numerical results are validated using the experimental results obtained from the mechanical experiments. Using the isotropic hardening crushable foam constitutive model, available on ABAQUS, a set of different mechanical tests were simulated. The isotropic hardening model available uses a yield surface that is an ellipse centered at the origin in the p-q stress plane. Using this constitutive model, the uniaxial tensile test for this material was simulated, and a comparison with the experimental results was made. [ABSTRACT FROM AUTHOR]

The role of an anti-intrusion bar for automotive use is to absorb the kinetic energy of the colliding bodies that is partially converted into internal work of the bodies involved in the crash. The aim of this paper is to investigate the performances of a new kind of anti-intrusion bars for automotive use, filled with metallic foams. The reason for using a cellular material as a filler deals with its capacity to absorb energy during plastic deformation, while being lightweight. The study is the evolution of a previous paper presented by the authors at Esaform 2010 and will present new results and findings. It is conducted by evaluating some key technical issues of the manufacturing problem and by conducting experimental and numerical analyses. The evaluation of materials and shapes of the closed sections to be filled is made in the perspective of a car manufacturer (production costs, weight reduction, space availability in a car door, etc.). Experimentally, foams are produced starting from an industrial aluminium precursor with a TiH2 blowing agent. Bars are tested in three point bending, in order to evaluate their performances in terms of force-displacement response and other specific performance parameters. In order to understand the role of interface between the inner surface of the tube and the external surface of the foam, different kinds of interface are tested. [ABSTRACT FROM AUTHOR]

The paper presents the result of an experimental investigation conducted on medium aluminum silicon alloy casting- LM6, using no-vacuum assisted lost foam casting process. The study is directed for establishing the relationship between the flask vibrations times developed for molded sample on the casting integrity, surface penetration and coating inclusion defects of the casting. Four different flask vibration times namely 180, 120, 90 and 60 sec. were investigated. The casting integrity was investigated in terms of fulfilling in all portions and edges. The surface penetration was measured using optical microscope whilst image analyzer was used to quantify the percentage of coating inclusion in the casting. The results show that vibration time has significant influence on the fulfilling as well as the internal integrity of the lost foam casting. It was found that the lower vibration time produced comparatively sound casing. [ABSTRACT FROM AUTHOR]

The aim of this paper is to verify the technological feasibility to realize hybrid metal-foam/composite component and the mechanical performances of the final structure. The hybrid component is composed by a cylindrical core in aluminum foam, the most used between those commercially available, and an outer layer in epoxy/S2-glass, manufactured by filament winding technology. A set of experimental tests have been carried out, to the aim to estimate the improvement of the hybrid component characteristics, compared to the sum of the single components (metal foam cylinder and epoxy/S2-glass tube). [ABSTRACT FROM AUTHOR]

This paper is devoted to simply supported sandwich beams with a metal foam core. The mechanical properties of the isotropic core of the beam are varied in a normal direction in relation to the middle plane of symmetry. Mathematical modelling of shear effect is presented. The fields of displacement for the flat cross section of the beam are defined. Basing on the principle of the stationary of the total potential energy the system of four partial differential equations is obtained. One way for solving the system of equilibrium equations is proposed. [ABSTRACT FROM AUTHOR]

Cross-connection in the foam struts helps achieving augmentation in heat transfer. It is the same feature which adds the risk of promoting axial conduction. Fluid flow through a slice of open-cell foam, attached to a plate, has been considered for analysing the effect of axial conduction through the porous medium. A repetitive simple cubic structure model for the porous matrix has been assumed for simplicity. While, thermal gradient in the solid plate is always associated with axial flow of heat, existence of the same through the foam filaments becomes conditional. Axial heat flow through the foam-fibres has been found causing substantial deterioration in heat transfer. [ABSTRACT FROM AUTHOR]

This paper aims at investigating the air heat transfer and fluid flow through eight Aluminum open cell foam samples with different number of pores per linear inch (PPI ranging between 5 and 40), almost constant porosity (around 0.92–0.93) and different foam core heights (20 and 40 mm). The experimental heat transfer coefficient and pressure drop measurements have been collected in a test rig built at Dipartimento di Fisica Tecnica of the University of Padova. Three different heat fluxes have been imposed: 25.0, 32.5 and 40.0 kW m-2 and the air mass flow rate has been varied between 0.005 and 0.025 kg s-1, with air approach velocity between 2 and 5 m s-1. The effect of the foam height on the heat transfer has been experimentally analysed. Finally, the pressure drop measurements have been compared against an analytical model suggested in the open literature. [ABSTRACT FROM AUTHOR]

As an engineering technology, open-cell metal foam has gained an expanded industrial and scientific interest. Many applications require fluid flow through the open pores of the foam. In general, metal foam is treated as a porous medium subject to porous-media flow relations, i.e., the Darcy and Hazen-Dupuit-Darcy (or Forchheimer) equations. Depending on the flow regime, the permeability, or the permeability and form drag coefficient, are usually obtained by fitting linear experimental pressure drop data as a function of seepage velocity, according to one of the above relations. The length of metal foam employed by researches is dictated by intended applications or by limitations on experimental set-ups. Little or no attention is paid to the effect of the length of the foam in the flow direction or the potential presence of entrance/exit effects. The current work is concerned with experimentally investigating the effects of entrance and exit of airflow in metal foam on the pressure drop. An experiment was conducted in a wind tunnel for velocities in the Forchheimer regime. An aluminum foam sample having a length of 30.5 cm in the flow direction and a square cross section of 10.16 cm2 was investigated. Pressure drop data was recorded at equal distances from the entrance and the exit. Results revealed strong entrance and exit effects over a significant portion of the sample. In both of these regions and for some velocities, the pressure drop did not conform to the Forchheimer equation. [ABSTRACT FROM AUTHOR]

Metallic foams are a new class of functional materials. They have found their application as sandwich cores in lightweight structures and have the potential as implant materials in bioengineering. To characterize the mechanical properties of these materials becomes an interesting and relevant research topic. In the mean time, indentation method has been well accepted as a simple and effective way to measure the mechanical properties of solid materials. We believe that it is possible to study the averaged mechanical properties of a metallic foam from a spherical indentation test. In this paper, theoretical investigation to understand the spherical indentation responses of metallic foams is presented. Based on the dimensional analysis and finite element calculations, several scaling relationships in the indentation of metallic foams with a spherical indenter were obtained. These scaling relationships illustrate the dependence of the indentation response on the material properties of metallic foams, such as porosity and plastic deformation shape factor. These results provide the basis for further research to develop spherical indentation methods to measure mechanical properties of metallic foams. [ABSTRACT FROM AUTHOR]

Subject of the paper is a simply supported rectangular sandwich plate. The plate is compressed in plane. It is assumed that the plate under consideration is symmetrical in build and consists of two isotropic facings and core. Middle plane of the plate is its symmetry plane. The core is made of metal foam with properties vary across its thickness. The porous-cellular metal as a core of three layered plate is of continuous structure, while its mechanical properties are isotropic. Dimensionless coefficients are introduced to compensate for this. The field of displacements and geometric relationships are assumed. This non-linear hypothesis is generalization of the classical hypotheses, in particular, the broken-line hypothesis. The principle of stationarity of the total potential energy of the compressed sandwich plate are used and a system of differential equations are formulated. This system is approximately solved. The forms of unknown functions are assumed, which satisfy boundary conditions for supports of the plate. Critical loads for a family of sandwich plates are numerically determined. Results of the calculation are shown in figures. [ABSTRACT FROM AUTHOR]