Hybrid Foams Research Articles

Improved energy absorption capacity of closed-cell aluminium foams by electroplating

ABSTRACT In the present study, hybrid closed-cell foams consisting of two materials with different ductilities were manufactured to improve the energy absorption capacity. The mechanical characteristics, deformation modes and energy absorption capacities of the foams were investigated. Furthermore, the energy absorption mechanisms of the hybrid foams were analysed. The results demonstrated a significant synergistic effect between the foams and coating with different ductilities during deformation. Their combination increased the densification strain and improved the energy absorption capacity of the samples. Among the specimens investigated, the Al/Zn–Cu(A) foam showed the best densification strain (0.75) and presented superior energy absorption capacities (energy absorption capacity per unit volume (U v) = 4.5 J cm–3; energy absorption capacity per unit mass (U m) = 8.4 J g–1). The intrinsic mechanism of energy absorption optimisation is a combination of the advantages of brittle and ductile deformation modes.

Fabricating bimodal microcellular structure in polystyrene/carbon nanotube/glass‐fiber hybrid nanocomposite foam by microwave‐assisted heating: A proof‐of‐concept study

AbstractIn the current study, polystyrene/carbon nanotubes/glass fiber (PS/CNT/GF) hybrid foam with a bimodal cellular‐structure has been fabricated via microwave heating as a novel energy source. Microwave‐assisted (MA) samples not only demonstrated the lowest density as compared to traditional methods but also represented superior compressive mechanical properties. Since the bimodal morphology has not been seen so far, the role of selective microwave heating has been thoroughly investigated from the microstructural point of view. Accordingly, the amount of receiving microwave radiations to heat up the system is controllable via the CNTs (as nucleating agents and absorbers) as well as radiation time. Moreover, 1–15 wt% fibers were incorporated to enhance mechanical performance, which led to turning uniform cellular structure to the bimodal pattern, and its cell morphological was studied thereafter. Electrical conductivity and dielectric permittivity properties have not been deprived of bimodality benefits which have been rigorously proven.

3d Mof@Graphene Foam Hybrids and Their Functional Implications for Supercilious Recovery of Precious Metals from E-Waste

3d Mof@Graphene Foam Hybrids and Their Functional Implications for Supercilious Recovery of Precious Metals from E-Waste

Ultralight, Compressible and Superhydrophobic Hybrid Foam with Highly Efficient Electromagnetic Interference Shielding in Damping and High Humidity Environment

Ultralight, Compressible and Superhydrophobic Hybrid Foam with Highly Efficient Electromagnetic Interference Shielding in Damping and High Humidity Environment

Constructing 3d Tent-Like Frameworks in Melamine Hybrid Foam for Superior Microwave Absorption and Thermal Insulation

Constructing 3d Tent-Like Frameworks in Melamine Hybrid Foam for Superior Microwave Absorption and Thermal Insulation

Effect of temperature and strain rate on the compressive deformation response of closed-cell aluminium hybrid foams

The hot deformation behaviour of Al-Si12CulMg1 alloy foam, Al-Si12CulMg1 alloy-single-wall carbon nanotubes (SWNTs), Al-Si12CulMg1-cenospheres, and Al-Si12CulMg1-cenosphere-SWNTs hybrid foams (HFs) were investigated at different test temperatures (25–400 °C) and strain rates (10-3-1 s-1) conditions. It is observed that the energy absorption capacity of all the foams decreased with an increased test temperature (TT) whereas it increased with an increase in strain rate. The hybrid foam in which the cenosphere and SWNTs were added together exhibited the highest plateau stress and energy absorption amongst all investigated foams. The strain rate sensitivity and activation energy for each kind of foam was calculated as a function of temperature and strain rate. The activation energy data tells that the deformation mechanism is dominated by vacancy and dislocation diffusion at TT≤ 200 °C regardless of the type of foam, strain rate and relative density. On the other hand, the deformation mechanism is dominated by dynamic recovery and recrystallization when the TT increase beyond 200 °C (TT>200 °C). This study further demonstrates the synergistic effect of cenosphere and SWNTs on enhancing the plateau stress and energy absorption of HFs.

Facile synthesis of ultra-lightweight silver/reduced graphene oxide (rGO) coated carbonized-melamine foams with high electromagnetic interference shielding effectiveness and high absorption coefficient

Endowing electromagnetic interference (EMI) shielding foams with ultralow density and dynamic stable structure is crucial yet challenging. Here, we propose a facile one-step thermal treatment strategy to fabricate lightweight silver/reduced graphene oxide-coated carbonized melamine (CMF/rGO/Ag) hybrid foams with remarkable mechanical performance and outstanding EMI shielding effectiveness (EMI SE). Due to interfacial reinforcement of rGO between CMF skeleton and silver, the CMF/rGO/Ag foams show outstanding structural stability after 1000 cycles of a loading-unloading compression test. Moreover, The EMI SE of the foams reaches 50.6 dB at a mere density of 16 mg cm−3. The normalized surface-specific SE is up to 7616 dB cm2 g−1 with an ultralow Ag content of 0.09 vol%. Interestingly, the collaboration of the porous skeleton and multiple interfaces contribute to an anomalous high absorption coefficient of CMF/rGO/Ag foams (over 0.5). The high-absorption-coefficient shielding mechanism of the CMF/rGO/Ag foams was further studied by finite element analysis (FEA). The remarkable near-field EMI shielding performance of the CMF/rGO/Ag foam demonstrates that the low density and robust CMF/rGO/Ag foam have enormous advantages and wide application prospects as EMI shielding materials of electronic packaging.

Challenges Faced While Designing Body in White

Abstract: Construction of Body in White (BiW) revolves around plenty of challenges. Ranging from BiW fixtures to curbing weight of Body in White sheet metal design. This paper discusses about all the design aspects in BiW manufacturing in automobile and confronting challenges that occurs. At present, lots of existing theories are being applied and efforts to improve the same are being made. This paper provides a path on how components can be developed and make necessary improvements. CAE (Computer Aided Engineering) tools have been used for FEA (Finite Element Analysis) and also an example of stress analysis of automotive chassis is given. An outcome depending on behaviour of loads acting on frame is drawn. The importance of hollow tubes, tubes of different- cross sections to counter weight and ease the designing of BiW frame have been proposed. This paper also provides insight on safety parameters with current construction of tubular frame chassis. Other solutions such as hybrid tubes, foam padding and plastic trim have been pointed out in this paper. Keywords: CAE, FEA, manufacturing, loads, tubes, cycle-time, cross-section.

Melting and energy storage characteristics of macro-encapsulated PCM-metal foam system

In this study a novel encapsulated phase change material (PCM)-metal foam hybrid system is proposed for energy storage applications. The idea is to improve the melting rate of PCM in encapsulated PCM systems with the introduction of metal foam structures inside the capsules. The main objective of the work is to develop a numerical model which can simulate the melting of PCM in this hybrid system due to the flow of heat transfer fluid (HTF) around the capsule with the resolution of the metal foam geometry at the pore-scale level. The developed model couples geometry creation, phase change and fluid flow models. The foam geometry is created using overlapping circular pores with random location, radii, and overlap. The phase change model is developed by modifying the enthalpy method to incorporate the presence of four phases – HTF, metal, solid PCM, and liquid PCM. This is coupled with an implicit flow solver within a finite volume framework. An in-depth analysis of a base case is conducted by fixing different geometrical parameters such as capsule size, porosity, pore size distribution and shell thickness. The results of the base case are then compared in subsequent parametric studies, by varying one geometrical parameter at a time. The parametric studies reveal that the structure of the metal foam plays an important role in determining the melting pattern and the energy storage characteristics because of its net-like large inner surface area. It is found that the melting time is reduced for lower capsule size, lower porosity, and higher shell thickness. The average pore size and range are crucial in determining the rate of melting.

A scalable, cost-effective and salt-rejecting MoS2/SA@melamine foam for continuous solar steam generation

Solar steam generation (STG) has been regarded as a promising strategy to relieve concerns on water shortage. Though great progresses have been made to improve the efficiency, salt deposition in the STG evaporator presents vital issues to an effective and continuous water production. Here, A MoS2-sodium alginate hydrogel wrapped melamine foam (MoS2/[email protected]) hybrid sponge is developed through simple, scalable and low-cost dipping–drying–crosslinking process. In this work, a 4 × 4 cm MoS2/[email protected] evaporator shows an evaporation rate of 1.92 kg/m2.h in 3.5 wt% NaCl solution under 1 kW.m−2, achieving a solar-thermal conversion efficiency of 90%. Additional to bimodal porous structure of the MF skeleton, thanks to meticulous designs, including drilling through-holes and cutting water-channels on the STG evaporator, the water transportation and salt ions convection are fully accelerated. It is systematically illustrated that a significant improvement in salt rejecting performance is achieved with a 1.81 kg/m2.h evaporation rate even after 100 h in a brine salinity up to 20 wt% under 1 kW.m−2. In addition, a consistent and effective solar-thermal conversion efficiency of 84.8% is also achieved superior to most reported works. Furthermore, this work also reveals that, in case of putting the evaporator float on the brine solution, Marangoni effect stemming from the temperature gradient and salinity concentration gradient at saltwater-air interface, plays an important role in salt deposition in the edge of PS foam and the side of MoS2/[email protected] hybrid sponge. The study also provides an effective strategy of isolating the evaporator from brine water to prevent Marangoni flow and enable its sustainable and practical applications.

Integration of MIL-101-NH2 into Cellulosic Foams for Efficient Cr(VI) Reduction under Visible Light

In this Article, a hybrid foam was fabricated through the integration of amine-functionalized Fe-MOF (MIL-101-NH2) into cellulosic matrix. The existence of enormous group linkages and ionic bonding...

Numerical and experimental investigations of the electrodeposition process on open porous foams, determination of the parameter influence on the coating homogeneity

The limited quantity of raw materials leads to application-optimised materials, such as open-cell hybrid foams. A nanocrystalline nickel coating significantly enhances the crash absorber properties of aluminum and PU foams with only a small increase in weight. The coating is applied by an electrodeposition process. Due to mass transport limitations during the process, an inhomogeneous coating thickness is created resulting in inhomogeneous material properties. To avoid different coating thicknesses at different points of the foam, the electrodeposition process in the foam is modelled and simulated. The results of the simulation are compared with experimental data and the influence of different parameters on the coating homogeneity is investigated by means of simulation.

Thermal performance evaluation of latent heat storage systems with plate fin-metal foam hybrid structure

The thermal performance of phase change materials (PCM) embedded with fins and metal foam is investigated. Plate fins are attached to the enclosure, and metal foam is embedded between adjacent fins to enhance heat transfer. To predict the melting behavior, a numerical model is established based on the enthalpy-porosity method, considering natural convection, flow resistance induced by metal foam, and non-equilibrium heat transfer. Nine cases considering various geometric parameters, heat transfer enhancement designs, and heated wall temperature are studied. Furthermore, a dimensionless theoretical model is derived to conclude the effect of combined parameters. It shows that the melting time reduces by 24.8 % as the fin height decreases from 80 mm to 50 mm, and the melting time becomes shorter with the decrease of fin thickness. However, the heat flux gets higher for higher fin height and thinner fin thickness. Moreover, the melting rate and heat flux become higher for higher fin volume fraction, lower metal foam porosity, and higher heated wall temperature. Furthermore, the theoretical model reveals that as Stefan number, fin efficiency, and the ratio of thermal diffusivity to the squared fin height become larger, the melting rate becomes higher.

Tailoring 3D printed graded architected polymer foams for enhanced energy absorption

Graded material design strategy has been exploited to achieve enhanced mechanical performance compared to their uniform counterpart. Using a combined numerical and experimental approach, we investigated the effects of three graded designs on the compressive mechanical performance of 3D printed architected polymer foams. The architected foam is composed of beam binders and spherical shells, which have pronounced effects on the mechanical performance under large deformations. It was found that three failure mechanisms dominate the mechanical behavior of foams for different binder sizes, including binder-failure-only, shell-failure-only, and binder-shell-failure. The investigation of shell thickness variation showed that the relation between relative stiffness and relative density is E/Es~(ρ/ρs)1.56, indicating a bending-dominant deformation behavior. Guided by these findings, we studied the mechanical behavior of three types of graded designs, including graded binder, graded shell thickness, and a hybrid strategy. It was found that the specific energy absorption of hybrid foam is enhanced by 125 %, 185 %, and 34 % compared to uniform foam, graded binder foam, and graded thickness foam, respectively. Furthermore, compared with existing lattice-based and shell-based graded foams, the stiffness of hybrid graded foam increases by 346 % and 33 %, respectively; the specific energy absorption of hybrid graded foam increases by 141 % and 32 %, respectively. The findings presented open a new avenue to engineer architected materials with enhanced mechanical properties, finding applications ranging from structural components of defense systems to protection systems in vehicles.

Broadband microwave-absorbing and energy-storing composite foam with pomegranate-like microstructure created from Pickering emulsion method

Rational design and construction on the microstructure of multifunctional microwave absorbing materials are significant strategy for upgrading their performances. Here, multifunctional hybrid foam with pomegranate-like microstructure are fabricated, which based on paraffin wax (PW)-in-water Pickering emulsion stabilized by cellulose nanofibrils (CNF). The in-situ polymerization of pyrrole monomer induced the creation of CNF/Fe3O4/PW/polypyrrole (PPy) hybrid foam, wherein PW microspheres were covered with CNF/Fe3O4/PPy nanocomposite shells. The obtained foam exhibited excellent microwave absorption performance with a reflection value (RL) of −55.6 dB and broadband bandwidth of 10.0 GHz (8.0–18.0 GHz). Owing to the specificity in the structure of hybrid foams with embedded PW microspheres, the maicrowave performance can be adjusted by regulating the amount of PW microspheres in composite foam. Moreover, pomegranate-like microwave-absorbing foams also show excellent photo-thermal conversion and energy storage, meaning this multifunctional composite foam has potential applications in microwave absorption, thermal energy storage systems, and smart buildings.

Robust and flexible silver-embedded elastomeric polymer/carbon black foams with outstanding electromagnetic interference shielding performance

Designing robust, flexible, and low metal consuming hybrid foams for high-performance electromagnetic interference (EMI) shielding is crucial yet challenging. A new metallization strategy of foam type materials is presented to fabricate the robust and flexible silver embedded poly (styrene-block-butadiene-block-styrene)/carbon black hybrid foam (Ag@SBS/CB) with ultra-low silver consumption. The synergistic effect between the embedded isolate Ag nanoparticles and carbon black endows the Ag@SBS/CB foam with high mechanical and electrical stability as well as outstanding EMI shielding performance. The Ag@SBS/CB foam can endure over 1500 cycles of the compression-release test without detectable decay in the relative conductivity. A significant influence of the pore size and the silver fraction on the EMI shielding performance is revealed, providing an intriguing microstructure design strategy. The EMI shielding effectiveness (SE) of the foam reaches 81.3 dB with the silver fraction of 0.63 vol% and a CB fraction of 15 wt% at a thickness of about 5 mm. In particular, the Ag@SBS/CB foam with a thinner thickness of 2 mm shows a much better near-field EMI shielding than Al plate.

Enhanced compressive and energy absorption properties of braided lattice and polyurethane foam hybrid composites

Ultralight structures with excellent specific mechanical properties have been of great interest in the field of transportation. In this study, a new ultralight hybrid material composed of braided lattice (BL) composite tubes and polyurethane (PU) foam was developed. First, BL preforms were produced using a braiding process, and BL composites were subsequently manufactured by resin impregnation and curing. The BL composites were inserted into a PU foam to make a hybrid composite. The compressive behavior of these hybrid composites was experimentally characterized, focusing on the effect of the number of BL layers and their cross-sectional shapes and perimeters on the energy-absorbing behavior. Furthermore, finite element (FE) modeling was conducted to investigate the energy absorption mechanism in the hybrid composites. A good correlation between FE modeling and experimental results was achieved, indicating that the hybrid composites exhibited significantly improved energy absorption properties due to the synergistic effects between foam and BL, outperforming similar ultralight cellular structures in terms of crashworthiness.

Ni/Al-Hybrid Cellular Foams: An Interface Study by Combination of 3D-Phase Morphology Imaging, Microbeam Fracture Mechanics and In Situ Synchrotron Stress Analysis.

Nickel(Ni)/aluminium(Al) hybrid foams are Al base foams coated with Ni by electrodeposition. Hybrid foams offer an enhanced energy absorption capacity. To ensure a good adhering Ni coating, necessary for a shear resistant interface, the influence of a chemical pre-treatment of the base foam was investigated by a combination of an interface morphology analysis by focused ion beam (FIB) tomography and in situ mechanical testing. The critical energy for interfacial decohesion from these microbending fracture tests in the scanning electron microscope (SEM) were contrasted to and the results validated by depth-resolved measurements of the evolving stresses in the Ni coating during three-point bending tests at the energy-dispersive diffraction (EDDI) beamline at the synchrotron BESSY II. Such a multi-method assessment of the interface decohesion resistance with respect to the interface morphology provides a reliable investigation strategy for further improvement of the interface morphology.

Compressive Properties of Electroless Ni-P Coating Reinforced Magnesium Alloy Foams

In this study, the open-cell Mg-2Zn-0.4Y foams were prepared by infiltration casting method. The Ni/Mg hybrid foams were prepared by electroless Ni-P coating on the foam struts to improve the compressive strength and energy absorption capacity. The compressive properties of the Mg alloy foams and Ni/Mg hybrid foams were studied by quasi-static compressive test. The experimental results show that the Ni-P coating is composed of crystallites. The Ni-P coating can significantly enhance the compressive strength, energy absorption capacity and energy absorption efficiency of the foams.

“Aerogel-like” polysiloxane-polyurethane hybrid foams with enhanced mechanical and thermal-insulating properties

New organic-inorganic polyurethane-based hybrids with enhanced mechanical properties and thermal insulation properties are reported. Polyurethane-based hybrids are characterized by the intimate interactions of their inorganic and organic co-networks and prepared by sol-gel approach, have exhibited properties exceeding those of polyurethane foams, e.g. enhanced thermal stability, durability and thermal insulating effectiveness. However, mechanical properties have previously been poor. Here, new porous organic-inorganic materials consisting of a polyurethane network modified by in-situ formation of aerogel-like polysiloxane domains, were developed. They exhibit a multiscale-porosity which enhances the insulation, mechanical and thermal properties. The synthesis was performed through a novel stepwise process consisting of: preparation of a siloxane precursor based on methyl-triethoxysilane and tetraethoxysilane; functionalization of traditional polyol for polyurethane foams with 3-(triethoxysilanepropyl)isocyanate as coupling agent; use of suitable catalysts and silicone surfactants; and foaming with methylene-di-isocyanate compound. The siloxane precursors and coupling agent led to formation of “aerogel-like” polysiloxane domains within the walls and struts of the polyurethane foams. The synthesis method enabled increased incorporation of the “aerogel-like” polysiloxane structures into the foams, compared to literature, with 20 wt% SiO2, reducing thermal conductivity of the hybrid foams 30% compared with pristine polyurethane, in addition to significant improvement in thermal stability and mechanical properties.