Special Issue "Advanced and High Performance Metallic Foams"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (15 December 2020).

Special Issue Editor

Dr. Imre Norbert Orbulov
E-Mail Website
Guest Editor
1. Department of Materials Science and Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Hungary
2. MTA-BME Lendület Composite Metal Foams Research Group, Hungarian Academy of Sciences, Hungary
Interests: metallic foams; metal matrix composites; mechanical testing; fatigue; fracture mechanics
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Metallic foams are ever and ever developing. Nowadays, advanced or high-performance metallic foams (such as low-cost, high-strength, high-stiffness, excellent energy absorbers, etc.) are emerging. Researchers in the metallic foams community are pushing the boundaries further and further to produce stronger, lighter, higher-performance foams.

It is my pleasure to invite you to publish your metallic foam-related research works in the Special Issue, ‘Advanced and High-Performance Metallic Foams’, of Materials as a full paper, short communication, or review. This Special Issue covers all types and aspects of metallic foams from design through production and intensive testing, including, but not limited to liquid- and solid-state and 3D additive production methods, blowing agents, foaming, macro-, meso-, and microstructures of foams, structural reverse engineering, modelling of metallic foams, quasi-static, dynamic and cyclic mechanical properties (compressive, tensile, and bending behavior, including blast protection and piercing) at room, elevated, or cryogenic temperature, mechanical damping, failure mechanisms and energy absorption of metallic foams, foam-filled structures and their mechanical stability, biocompatible foams, degradable and recyclable metallic foams, joining technologies (brazing, welding, gluing, etc.), forming of metallic foams, notch and hole sensitivity, applications and case studies.

Dr. Imre Norbert Orbulov
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Metallic foams
  • Foaming
  • Mechanical testing
  • Mechanical properties
  • Mechanical damping
  • Microstructure
  • Additive manufacturing
  • Reverse engineering
  • Blast protection
  • Failure mechanism
  • Biocompatible foam

Published Papers (13 papers)

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Editorial

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Open AccessEditorial
Special Issue ‘Advanced and High Performance Metallic Foams’
Materials 2021, 14(5), 1092; https://doi.org/10.3390/ma14051092 - 26 Feb 2021
Viewed by 264
Abstract
Metallic foams are developing more and more [...] Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)

Research

Jump to: Editorial

Open AccessArticle
The Optical and Electrical Performance of CuO Synthesized by Anodic Oxidation Based on Copper Foam
Materials 2020, 13(23), 5411; https://doi.org/10.3390/ma13235411 - 27 Nov 2020
Cited by 1 | Viewed by 561
Abstract
Metal oxide semiconductor materials have a wide range of applications in the field of solar energy conversion. In this paper, CuO was prepared directly on copper foam substrate by anodic oxidation. The effects of current density and anodizing temperature on sample preparation and [...] Read more.
Metal oxide semiconductor materials have a wide range of applications in the field of solar energy conversion. In this paper, CuO was prepared directly on copper foam substrate by anodic oxidation. The effects of current density and anodizing temperature on sample preparation and performance were studied. Field emission scanning electron microscopy (FESEM) and X-ray diffractometer (XRD) had been used to determine the morphology and phase structure of the sample, and its optical and electrical properties were discussed through UV-vis spectrophotometer and electrochemical tests. In addition, the influences of experimental conditions such as current density and reaction temperature on the morphology and properties of CuO were systematically discussed. The FESEM images showed that as the anodic oxidation temperature increase, the morphology of the prepared sample changed from nanowires to leaf-like CuO nanosheets. According to the results of XRD, the structure of prepared CuO was monoclinic, and the intensity of diffraction peaks gradually increased as anodizing temperature increased. We found that the optimum current density and anodizing temperature were 20 mA cm−2 and 60 °C, respectively. The results of electrochemical indicated that the CuO electrode based on copper foam (CuO/Cu foam) prepared at the optimum exhibited the highest specific capacitance (0.1039 F cm−2) when the scan rate was 2 mV s−1. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
Theoretical Analysis of Blast Protection of Graded Metal Foam-Cored Sandwich Cylinders/Rings
Materials 2020, 13(17), 3903; https://doi.org/10.3390/ma13173903 - 03 Sep 2020
Cited by 2 | Viewed by 650
Abstract
The blast resistance of a sandwich-walled cylinder/ring comprising two metal face-sheets and a graded metal foam core, subjected to internal air blast loading, is investigated. Analytical models are developed for the deformation of the sandwich cylinder with positive and negative gradient cores under [...] Read more.
The blast resistance of a sandwich-walled cylinder/ring comprising two metal face-sheets and a graded metal foam core, subjected to internal air blast loading, is investigated. Analytical models are developed for the deformation of the sandwich cylinder with positive and negative gradient cores under internal blast loading. The deformation process is divided into three distinct phases, namely the fluid–structure interaction phase, core-crushing phase, and outer face-sheet deformation phase. Finite element modeling is performed using the Voronoi material model. The proposed analytical models are verified through finite element analysis, and reasonable agreement is observed between the analytical predictions and finite element results. The sandwich structures with high energy absorption capacity or low maximum radial deflection are satisfied for the protecting purpose of impact/blast resistance requirements. Typical deformation processes are classified and analyzed; the effects of explosive charge, face-sheet thickness, and core gradient on the structural response are also examined. The results indicate that both the deformation modes and the structural response of the cylinders are sensitive to the blast charge and core configuration. It is concluded that energy absorption capacity and maximum radial deflection are two conflicting goals for achieving high impact/blast resistance capability. An in-depth understanding of the behavior in sandwich-walled cylinders under blast impulse and the influence of the core configuration helps realize the advantages and disadvantages of using graded foam materials in sandwich structures and can provide a guideline for structural design. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
Development of Unidirectional Cellular Structure with Multiple Pipe Layers and Characterisation of Its Mechanical Properties
Materials 2020, 13(17), 3880; https://doi.org/10.3390/ma13173880 - 02 Sep 2020
Cited by 1 | Viewed by 563
Abstract
This study is concerned with the development of a new unidirectional cellular (UniPore) copper structure with multiple concentric pipe layers. The investigated UniPore structures were grouped into three main types, each having a different number of pipes (3, 4, and 5 pipes per [...] Read more.
This study is concerned with the development of a new unidirectional cellular (UniPore) copper structure with multiple concentric pipe layers. The investigated UniPore structures were grouped into three main types, each having a different number of pipes (3, 4, and 5 pipes per transversal cross-section) and different pore arrangements. The specimens were fabricated by explosive compaction to achieve tightly compacted structures with a quasi-constant cross-section along the length of the specimens. The bonding between copper pipes was observed by a metallographic investigation, which showed that the pipes and bars were compressed tightly without voids. However, they were not welded together. The mechanical properties were determined by quasi-static compressive testing, where the typical behaviour for cellular materials was noted. The study showed that porosity significantly influences the mechanical properties, even more so than the arrangement of the pipes. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
Influence of Hydrodynamic Conditions on the Type and Area of Occurrence of Gas–Liquid Flow Patterns in the Flow through Open–Cell Foams
Materials 2020, 13(15), 3254; https://doi.org/10.3390/ma13153254 - 22 Jul 2020
Cited by 3 | Viewed by 450
Abstract
This paper reports the results of a study concerned with air−water and air−oil two–phase flow pattern analysis in the channels with open–cell metal foams. The research was conducted in a horizontal channel with an internal diameter of 0.02 m and length of 2.61 [...] Read more.
This paper reports the results of a study concerned with air−water and air−oil two–phase flow pattern analysis in the channels with open–cell metal foams. The research was conducted in a horizontal channel with an internal diameter of 0.02 m and length of 2.61 m. The analysis applied three foams with pore density equal to 20, 30 and 40 PPI (pore per inch) with porosity, typical for industrial applications, changing in the range of 92%–94%. Plug flow, slug flow, stratified flow and annular flow were observed over the ranges of gas and liquid superficial velocities of 0.031–8.840 m/s and 0.006–0.119 m/s, respectively. Churn flow, which has not yet been observed in the flow through the open–cell foams, was also recorded. The type of flow patterns is primarily affected by the hydrodynamic characteristics of the flow, including fluid properties, but not by the geometric parameters of foams. Flow patterns in the channels packed with metal foams occur in different conditions from the ones recorded for empty channels so gas−liquid flow maps developed for empty channels cannot be used to predict analyzed flows. A new gas−liquid flow pattern map for a channel packed with metal foams with the porosity of 0.92–0.94 was developed. The map is valid for liquids with a density equal to or lower than the density of water and a viscosity several times greater than that of water. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
Fracture Toughness of Hollow Glass Microsphere-Filled Iron Matrix Syntactic Foams
Materials 2020, 13(11), 2566; https://doi.org/10.3390/ma13112566 - 04 Jun 2020
Cited by 3 | Viewed by 624
Abstract
In this study, iron-based metal matrix syntactic foam (MMSF) containing hollow glass microspheres as filler was investigated with respect to notch sensitivity aspects. The MMSF was produced by means of metal powder injection molding. The notch sensitivity was studied via (i) elastic-plastic fracture [...] Read more.
In this study, iron-based metal matrix syntactic foam (MMSF) containing hollow glass microspheres as filler was investigated with respect to notch sensitivity aspects. The MMSF was produced by means of metal powder injection molding. The notch sensitivity was studied via (i) elastic-plastic fracture mechanics measurements (determination of R-curves based on three-point bending tests) and (ii) Charpy impact tests. In both cases, the samples were machined with two different (U- and V-shaped) notch geometries. The critical J-integral value was determined for both notch types, which resulted in lower fracture toughness values in the case of the V-shaped notches and thus notch sensitivity of the material. This finding can be connected to the characteristics of the deformation zone and the associated stress concentration at the tip of the machined notches. The results were confirmed by Charpy impact tests showing ~30% higher impact energy in the case of the U-shaped notch. The failure modes were investigated by means of scanning electron microscopy. In contrast to the bulk material, the MMSF showed brittle fracture behavior. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
2D Finite Element Modeling of the Cutting Force in Peripheral Milling of Cellular Metals
Materials 2020, 13(3), 555; https://doi.org/10.3390/ma13030555 - 23 Jan 2020
Cited by 5 | Viewed by 830
Abstract
The machining of cellular metals has been a challenge, as the resulting surface is extremely irregular, with torn off or smeared material, poor accuracy, and subsurface damage. Although cutting experiments have been carried out on cellular materials to study the influence of cutting [...] Read more.
The machining of cellular metals has been a challenge, as the resulting surface is extremely irregular, with torn off or smeared material, poor accuracy, and subsurface damage. Although cutting experiments have been carried out on cellular materials to study the influence of cutting parameters, current analytical and experimental techniques are not suitable for the analysis of heterogeneous materials. On the other hand, the finite element (FE) method has been proven a useful resource in the analysis of heterogeneous materials, such as cellular materials, metal foams, and composites. In this study, a two-dimensional finite element model of peripheral milling for cellular metals is presented. The model considers the kinematics of peripheral milling, depicting the advance of the tool into the workpiece and the interaction between the cutting edge and the mesostructure. The model is able to simulate chip separation as well as the surface and subsurface damage on the machined surface. Although the calculated average cutting force is not accurate, the model provides a reasonable estimation of maximum cutting force. The influences of mesostructure on cutting processes are highlighted and the effects in peripheral milling of cellular materials are discussed. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
Damage Characterization during Compression in a Perlite-Aluminum Syntactic Foam
Materials 2019, 12(20), 3342; https://doi.org/10.3390/ma12203342 - 14 Oct 2019
Cited by 3 | Viewed by 609
Abstract
Aluminum matrix (Al99.5) syntactic foam containing expanded perlite particles was produced using the pressure infiltration technique. The dominant deformation mechanisms during compression of this foam were determined by sequential k-means analysis of the acoustic emission data. Since the different deformation mechanisms were concurrently [...] Read more.
Aluminum matrix (Al99.5) syntactic foam containing expanded perlite particles was produced using the pressure infiltration technique. The dominant deformation mechanisms during compression of this foam were determined by sequential k-means analysis of the acoustic emission data. Since the different deformation mechanisms were concurrently active even at small strains, successive unloading and reloading measurement was proposed for cluster identification. The repetitive unloading and reloading allowed us to identify two mechanical parameters, namely the unloading modulus and the loss for unloading-reloading cycles. Based on the correlations among the strain localization within the specimen, the acoustic emission results, the changes in these mechanical parameters, and the transition from quasi-elastic deformation to plasticity were revealed in this material. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
On the Filler Materials of Metal Matrix Syntactic Foams
Materials 2019, 12(12), 2023; https://doi.org/10.3390/ma12122023 - 24 Jun 2019
Cited by 7 | Viewed by 1008
Abstract
Metal matrix syntactic foams (MMSFs) are becoming increasingly relevant from the lightweight structural materials point of view. They are also used as energy absorbers and as core materials for sandwich structures. The mechanical properties of MMSFs are extensively influenced by the properties of [...] Read more.
Metal matrix syntactic foams (MMSFs) are becoming increasingly relevant from the lightweight structural materials point of view. They are also used as energy absorbers and as core materials for sandwich structures. The mechanical properties of MMSFs are extensively influenced by the properties of their filler materials which are used to create and ensure the porosity inside the metal matrix. As the properties of fillers are of such importance in the case of MMSFs, in this paper three different filler materials: (i) ceramic hollow spheres (CHSs), (ii) metallic hollow spheres (MHSs) and (iii) lightweight expanded clay particles (LECAPs), have been investigated in numerous aspects. The investigations cover the microstructural features of the fillers and the basic mechanical properties of the fillers and the produced MMSFs as well. The microstructure was studied by optical and electron microscopy extended by energy-dispersive X-ray spectrometry, while the basic mechanical properties were mapped by standardized compression tests. It was found that in the terms of cost-awareness the LECAPs are the best fillers, because they are ~100 times cheaper than the CHSs or MHSs, but their mechanical properties can be compared to the aforementioned, relatively expensive filler materials and still exceed the properties of the most ‘conventional’ metallic foams. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
Mechanical Characterization of Different Aluminium Foams at High Strain Rates
Materials 2019, 12(9), 1428; https://doi.org/10.3390/ma12091428 - 01 May 2019
Cited by 8 | Viewed by 1052
Abstract
Samples having nominal compositions of AlSi12 and Al6082-T4 were prepared using a lost wax casting process, with nominal relative densities of 20%, 40%, and 60%, as well as arrangements of a uniform cell structure (US) or a dual-size cell (DS). For comparison, samples [...] Read more.
Samples having nominal compositions of AlSi12 and Al6082-T4 were prepared using a lost wax casting process, with nominal relative densities of 20%, 40%, and 60%, as well as arrangements of a uniform cell structure (US) or a dual-size cell (DS). For comparison, samples of aluminium foam-filled tubes having the same nominal composition were also prepared with the same technique, with nominal relative densities of 20% and similar arrangements (US and DS). Impact tests at different velocities were performed using a split Hopkinson pressure bar (SHPB). It is possible to conclude that Al6082-T4 foams have better performance, in both configurations, than the AlSi12 ones. Considering a uniform cell structure and a density of 20%, the absorbed energy by the Al6082-T4 foams was around 25% higher than the value observed for the AlSi12 ones. In terms of arrangement, the US structure presents absorbed energy around 57% lower than the DS ones, while the AlSi12 foams with a relative density of 20% were compared. Finally, the absorbed energy growths from 2.8 × 105 to 5.2 × 105 J/m3, when the density increased from 20% to 60%. However, when these foams were involved with a tube, the performances increased substantially. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
Characterization of Geometrical Changes of Spherical Advanced Pore Morphology (APM) Foam Elements during Compressive Deformation
Materials 2019, 12(7), 1088; https://doi.org/10.3390/ma12071088 - 02 Apr 2019
Cited by 3 | Viewed by 949
Abstract
The mechanical properties of Advanced Pore Morphology (APM) foam elements depend strongly upon their internal porous and external structural geometry. This paper reports on a detailed investigation of external (e.g. shape and size) and internal (e.g. distribution, size, number of pores) geometry and [...] Read more.
The mechanical properties of Advanced Pore Morphology (APM) foam elements depend strongly upon their internal porous and external structural geometry. This paper reports on a detailed investigation of external (e.g. shape and size) and internal (e.g. distribution, size, number of pores) geometry and porosity changes of APM foam elements, during compressive loading by means of the ex-situ micro-Computed Tomography, and advanced digital image analysis and recognition. The results show that the porosity of APM foam elements decreases by only 25% at the engineering strain of 70% due to an increase of the number of pores at high stages of compressive deformation. The APM foam elements also exhibit a positive macroscopic Poisson’s ratio of υ = 0.2, which is uncharacteristic for cellular structures. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessArticle
Effect of Heat Treatment on the Compressive Behavior of Zinc Alloy ZA27 Syntactic Foam
Materials 2019, 12(5), 792; https://doi.org/10.3390/ma12050792 - 07 Mar 2019
Cited by 20 | Viewed by 1340
Abstract
Zinc alloy (ZA27) syntactic foams (SF) were manufactured using expanded perlite (EP) particles and counter-gravity infiltration casting. Due to a variation of the metallic matrix content, the density of the produced foam samples varied from 1.78 to 2.03 g·cm−3. As-cast and [...] Read more.
Zinc alloy (ZA27) syntactic foams (SF) were manufactured using expanded perlite (EP) particles and counter-gravity infiltration casting. Due to a variation of the metallic matrix content, the density of the produced foam samples varied from 1.78 to 2.03 g·cm−3. As-cast and solution heat-treated samples were tested to investigate the compressive properties of the ZA27 syntactic foam. To this end, quasi-static compression tests were conducted. In addition, microstructural analysis of the as-cast and heat-treated syntactic foams was carried out using scanning electron microscopy. The results indicate that the heat treatment alters the microstructure of the ZA27 alloy matrix from a multiphase dendrite to a spheroidized microstructure with improved ductility. Moreover, the heat treatment considerably enhances the energy absorption and plateau stress ( σ pl ) of the syntactic foam. Optical analysis of the syntactic foams under compression shows that the dominant deformation mechanism of the as-cast foams is brittle fracture. In comparison, the heat-treated samples undergo a more ductile deformation. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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Open AccessFeature PaperArticle
Notch (In)Sensitivity of Aluminum Matrix Syntactic Foams
Materials 2019, 12(4), 574; https://doi.org/10.3390/ma12040574 - 14 Feb 2019
Cited by 9 | Viewed by 1159
Abstract
Aluminum alloy (Al99.5 or AlSi12)-based metal matrix syntactic foams (MMSFs) were produced by pressure infiltration with ~65 vol % Globocer filler (33 wt % Al2O3, 48 wt % SiO2, 19 wt % Al2O3∙SiO [...] Read more.
Aluminum alloy (Al99.5 or AlSi12)-based metal matrix syntactic foams (MMSFs) were produced by pressure infiltration with ~65 vol % Globocer filler (33 wt % Al2O3, 48 wt % SiO2, 19 wt % Al2O3∙SiO2). The infiltrated blocks were machined by different geometry tools in order to produce notched samples. The samples were loaded in three-point bending, and the loading force values were recorded against the cross-head displacements and the crack opening displacements. To measure up the notch sensitivity and toughness of the MMSFs, the fracture energies and the fracture toughness values were determined. The results showed that the mentioned quantities are needed to describe the behavior of MMSFs. The fracture energies were shown to be notch-sensitive, while the fracture toughness values were dependent only on the matrix material and were insensitive to the notch geometry. The complex investigation of the fracture surfaces revealed strong bonding between the hollow spheres and the Al99.5 matrix due to a chemical reaction, while this bonding was found to be weaker in the case of the AlSi12 matrix. This difference resulted in completely different crack propagation modes in the case of the different matrices. Full article
(This article belongs to the Special Issue Advanced and High Performance Metallic Foams)
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