Compressive Behavior and Microstructural Characteristics of Iron Hollow Sphere Filled Aluminum Matrix Syntactic Foams.
Ontology highlight
ABSTRACT:
SUBMITTER: Szlancsik A
PROVIDER: S-EPMC5458885 | biostudies-other | 2015 Nov
REPOSITORIES: biostudies-other
Similar Datasets
Project description:The present study investigates the mechanical performance of syntactic foams produced by means of the metal powder injection molding process having an Invar (FeNi36) matrix and including cenospheres as hollow particles at weight fractions (wt.%) of 5 and 10, respectively, corresponding to approximately 41.6 and 60.0 vol.% in relation to the metal content and at 0.6 g/cm³ hollow particle density. The synthesis process results in survival of cenospheres and provides low density syntactic foams. The microstructure of the materials is investigated as well as the mechanical performance under quasi-static and high strain rate compressive loads. The compressive stress-strain curves of syntactic foams reveal a continuous strain hardening behavior in the plastic region, followed by a densification region. The results reveal a strain rate sensitivity in cenosphere-based Invar matrix syntactic foams. Differences in properties between cenosphere- and glass microsphere-based materials are discussed in relation to the findings of microstructural investigations. Cenospheres present a viable choice as filler material in iron-based syntactic foams due to their higher thermal stability compared to glass microspheres.
| S-EPMC5456466 | biostudies-other
Project description:This work experimentally investigates the effect of layered structure on the static and impact response of a new layered syntactic foam developed for impact energy absorption. The layered syntactic foam had the same density of 1.6 g/cm3 and the same components of 50% large spheres (L) and 50% small spheres (S) with different structures from two layers to five layers. The impact response and energy absorption were investigated by drop-weight impact tests. Under static loading, more layers led to higher yield stress and lower energy absorption. There were three types of progressive failures of layered syntactic form under impact loading. The failure propagation was examined and found to be dependent on the layer number and impact energy. Interestingly, layered syntactic foam absorbed more energy than both of its components in terms of ductility. The ductility of layered syntactic foam decreased with the increase in layer number. The peak stress of layered syntactic foam increased with the increase in layer number. Two-layered syntactic foam LS had the highest ductility under 60 J/g impact, as well as an energy absorption of 35 J/g, compared to other layered syntactic foams. Specifically, its component L had a ductility under 70 J/g and an energy absorption of 25 J/g, while component S had a ductility under 10 J/g and an energy absorption of 10 J/g.
| S-EPMC6947444 | biostudies-literature
Project description:Magnesium alloys have considerably lower density than the aluminum alloy matrices that are typically used in syntactic foams, allowing for greater specific energy absorption. Despite the potential advantages, few studies have reported the properties of magnesium alloy matrix syntactic foams. In this work, Al₂O₃ hollow particles of three different size ranges, 0.106-0.212 mm, 0.212-0.425 mm, and 0.425-0.500 mm were encapsulated in Mg-AZ91D by a sub-atmospheric pressure infiltration technique. It is shown that the peak strength, plateau strength and toughness of the foam increases with increasing hollow sphere wall thickness to diameter (t/D) ratio. Since t/D was found to increase with decreasing hollow sphere diameter, the foams produced with smaller spheres showed improved performance-specifically, higher energy absorption per unit weight. These foams show better performance than other metallic foams on a specific property basis.
| S-EPMC5512899 | biostudies-other
Project description:Microstructural observations and compressive property datasets of metal matrix syntactic foam core sandwich composite at quasi-static and high strain rate (HSR) conditions (525-845 s(-1)) are provided. The data supplied in this article includes sample preparation procedure prior to scanning electron and optical microscopy as well as the micrographs. The data used to construct the stress-strain curves and the derived compressive properties of all specimens in both quasi-static and HSR regions are included. Videos of quasi-static compressive failure and that obtained by a high speed image acquisition system during deformation and failure of HSR specimen are also included.
| S-EPMC4624990 | biostudies-literature
Project description:Metal foam inserts are known for their high potential for weight and vibration reduction in composite gear wheels. However, most metal foams do not meet the strength requirements mandatory for the transfer of sufficiently high levels of torque by the gears. Syntactic iron and steel foams offer higher strength levels than conventional two-phase metal foams, thus making them optimum candidates for such inserts. The present study investigates to what extent surface hardening treatments commonly applied to gear wheels can improve the mechanical properties of iron-based syntactic foams. Experiments performed thus focus on case hardening treatments based on carburizing and carbonitriding, with subsequent quenching and tempering to achieve surface hardening effects. Production of samples relied on the powder metallurgical metal injection molding (MIM) process. Syntactic iron foams containing 10 wt.% of S60HS hollow glass microspheres were compared to reference materials without such filler. Following heat treatments, the samples' microstructure was evaluated metallographically; mechanical properties were determined via hardness measurements on reference samples and 4-point bending tests, on both reference and syntactic foam materials. The data obtained show that case hardening can indeed improve the mechanical performance of syntactic iron foams by inducing the formation of a hardened surface layer. Moreover, the investigation indicates that the respective thermo-chemical treatments can be applied to composite gear wheels in exactly the same way as to monolithic ones. In the surface region modified by the treatment, martensitic microstructures were observed, and as consequence, the bending limits of syntactic foam samples were increased by a factor of three.
| S-EPMC8398341 | biostudies-literature
Project description:The influence of the matrix material on the deformation and failure mechanisms in metal matrix syntactic foams was investigated in this study. Samples with commercially pure Al (Al) and Al-12 wt % Si (AlSi12) eutectic aluminum matrix, reinforced by hollow ceramic spheres, were compressed at room temperature. Concurrently, the acoustic emission response and the strain field development on the surface were monitored in-situ. The results indicate that the plastic deformation of the cell walls is the governing mechanism in the early stage of straining for both types of foams. At large stresses, deformation bands form both in the Al and AlSi12 foam. In Al foam, cell walls collapse in a large volume. In contrast, the AlSi12 foam is more brittle; therefore, the fracture of precipitates and the crushing of the matrix take place within a distinctive deformation band, along with an occurrence of a significant stress drop. The onset stress of ceramic sphere failure was shown to be not influenced by the matrix material. The in-situ methods provided complementary data which further support these results.
| S-EPMC5459142 | biostudies-literature
Project description:Syntactic foams are particulate composite materials that are extensively integrated in naval and aerospace structures as core materials for sandwich panels. While several studies have demonstrated the potential of syntactic foams as energy absorbing materials in impact tests, our understanding of their response to water impact remains elusive. In this work, we attempt a first characterization of the behavior of a vinyl ester/glass syntactic subject to slamming. High-speed imaging is leveraged to elucidate the physics of water impact of syntactic foam wedges in a free-fall drop tower. From the images, we simultaneously measure the deformation of the wedge and the hydrodynamic loading, thereby clarifying the central role of fluid-structure interaction during water impact. We study two different impact heights and microballoon density to assess the role of impact energy and syntactic foam composition on the slamming response. Our results demonstrate that both these factors have a critical role on the slamming response of syntactic foams. Reducing the density of microballoons might help to reduce the severity of the hydrodynamic loading experienced by the wedge, but this comes at the expense of a larger deformation. Such a larger deformation could ultimately lead to failure for large drop heights. These experimental results offer compelling evidence for the role of hydroelastic coupling in the slamming response of syntactic foams.
| S-EPMC5503347 | biostudies-other
Project description:Sub-50 nm iron-nitrogen-doped hollow carbon sphere-encapsulated iron carbide nanoparticles (Fe3C-Fe,N/C) are synthesized by using a triblock copolymer of poly(styrene-b-2-vinylpyridine-b-ethylene oxide) as a soft template. Their typical features, including a large surface area (879.5 m2 g-1), small hollow size (≈16 nm), and nitrogen-doped mesoporous carbon shell, and encapsulated Fe3C nanoparticles generate a highly active oxygen reduction reaction (ORR) performance. Fe3C-Fe,N/C hollow spheres exhibit an ORR performance comparable to that of commercially available 20 wt% Pt/C in alkaline electrolyte, with a similar half-wave potential, an electron transfer number close to 4, and lower H2O2 yield of less than 5%. It also shows noticeable ORR catalytic activity under acidic conditions, with a high half-wave potential of 0.714 V, which is only 59 mV lower than that of 20 wt% Pt/C. Moreover, Fe3C-Fe,N/C has remarkable long-term durability and tolerance to methanol poisoning, exceeding Pt/C regardless of the electrolyte.
| S-EPMC6051398 | biostudies-literature
Project description:To solve the problem of critical buckling in the structural analysis and design of the new long-span hollow core roof architecture proposed in this paper (referred to as a "honeycomb panel structural system" (HSSS)), lateral compression tests and finite element analyses were employed in this study to examine the lateral compressive buckling performance of this new type of honeycomb panel with different length-to-thickness ratios. The results led to two main conclusions: (1) Under the experimental conditions that were used, honeycomb panels with the same planar dimensions but different thicknesses had the same compressive stiffness immediately before buckling, while the lateral compressive buckling load-bearing capacity initially increased rapidly with an increasing honeycomb core thickness and then approached the same limiting value; (2) The compressive stiffnesses of test pieces with the same thickness but different lengths were different, while the maximum lateral compressive buckling loads were very similar. Overall instability failure is prone to occur in long and flexible honeycomb panels. In addition, the errors between the lateral compressive buckling loads from the experiment and the finite element simulations are within 6%, which demonstrates the effectiveness of the nonlinear finite element analysis and provides a theoretical basis for future analysis and design for this new type of spatial structure.
| S-EPMC5456758 | biostudies-other
Project description:Practical applications and mathematical modelling of the physical and mechanical properties of medium-density rigid polyurethane foams require knowledge of their structure. It is necessary to determine structural characteristics without destroying the foams and measuring each element. A methodology is described for the use of light microscopy on environmentally sustainable, medium-density rigid polyurethane foams (in the density region of ≈210-230 kg/m3), by the analysis of two types of light microscopy images: (1) Cutting surface images; and (2) Through-cutting surface images. The dimensions of structural elements of polyurethane foams, filled with the nanoclay Cloisite-30B at concentrations of 0.0%, 0.25%, 0.50%, 1.0%, 2.0%, 3.0%, and 5.0% from the mass of the filled reacting mixture, are estimated. Probability density functions of projections of bubbles' diameters and struts' length are determined using images in three mutually perpendicular planes. A mathematical model is developed for the restoration of the actual dimensions of bubbles' diameters using data of cutting circles' diameters. Intercalation and exfoliation of the filler's Cloisite-30B mono-layers is evaluated via the basal spacing by X-ray diffraction at a 5 wt.% concentration of nanoclay.
| S-EPMC8955111 | biostudies-literature