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New Advances in Characterization of Cellular Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Porous Materials".

Deadline for manuscript submissions: closed (10 May 2023) | Viewed by 20359

Special Issue Editors

Faculty of Mechanics, Polytechnic University of Timisoara, 1 Mihai Viteazu Ave., 300222 Timisoara, Romania
Interests: the application of fracture mechanics to engineering structures; fatigue life assessment; experimental fracture mechanics
Special Issues, Collections and Topics in MDPI journals
Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, 845 13 Bratislava, Slovakia
Interests: aliminum and zinc foams; porous solids; properties characterization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

There has been an increase in the use of cellular materials in different industries. This Special Issue represents a good opportunity for researchers to disseminate new advances related to the behavior of cellular materials such as, for example, different manufacturing routes, advances in microstructure observations and measurement of cellular material properties, the relationship between microstructure and mechanical and physical properties, damping characterization, surface and volume treatment, advances in simulation and modeling of cellular material behavior, behavior of sandwich structures with cellular material cores, novel cellular structures. Both natural (cork or wood, bones) and manufactured (polymeric, metallic, and ceramic foams, honeycomb) cellular structures will be considered.

Prof. Dr. Liviu Marsavina
Dr. Jaroslav Kovacik
Guest Editors

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 2600 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

  • cellular structures
  • foams
  • physical and mechanical properties
  • microstructure
  • manufacturing routes

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Published Papers (11 papers)

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Research

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11 pages, 4573 KiB  
Article
Study of Viscoelastic Properties of Graphene Foams Using Dynamic Mechanical Analysis and Coarse-Grained Molecular Dynamics Simulations
by Shenggui Liu, Mindong Lyu, Cheng Yang, Minqiang Jiang and Chao Wang
Materials 2023, 16(6), 2457; https://doi.org/10.3390/ma16062457 - 20 Mar 2023
Viewed by 1446
Abstract
As a promising nano-porous material for energy dissipation, the viscoelastic properties of three-dimensional (3D) graphene foams (GrFs) are investigated by combining a dynamic mechanical analysis (DMA) and coarse-grained molecular dynamic (CGMD) simulations. The effects of the different factors, such as the density of [...] Read more.
As a promising nano-porous material for energy dissipation, the viscoelastic properties of three-dimensional (3D) graphene foams (GrFs) are investigated by combining a dynamic mechanical analysis (DMA) and coarse-grained molecular dynamic (CGMD) simulations. The effects of the different factors, such as the density of the GrFs, temperature, loading frequency, oscillatory amplitude, the pre-strain on the storage and loss modulus of the GrFs as well as the micro-mechanical mechanisms are mainly focused upon. Not only the storage modulus but also the loss modulus are found to be independent of the temperature and the frequency. The storage modulus can be weakened slightly by bond-breaking with an increasing loading amplitude. Furthermore, the tensile/compressive pre-strain and density of the GrFs can be used to effectively tune the viscoelastic properties of the GrFs. These results should be helpful not only for understanding the mechanical mechanism of GrFs but also for optimal designs of advanced damping materials. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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14 pages, 5320 KiB  
Article
Development of Alkali-Activated Porous Concrete Composition from Slag Waste
by Gintautas Tamošaitis, Danute Vaičiukynienė, Tomas Jaskaudas, Jurate Mockiene and Darius Pupeikis
Materials 2023, 16(4), 1360; https://doi.org/10.3390/ma16041360 - 06 Feb 2023
Cited by 5 | Viewed by 1267
Abstract
In this paper, a porous alkali-activated slag concrete was developed that can be used in the construction sector as a sustainable building material and potentially as an alternative to the aerated concrete products currently on the market. Ferrous slag from the metallurgical industry [...] Read more.
In this paper, a porous alkali-activated slag concrete was developed that can be used in the construction sector as a sustainable building material and potentially as an alternative to the aerated concrete products currently on the market. Ferrous slag from the metallurgical industry (Finland) and phosphogypsum from a fertilizer plant (Lithuania) were used as precursors in alkali-activated systems. The addition of hydrogen peroxide and phosphogypsum led to positive changes in the final properties of the test material. Porous concrete based on alkali-activated slag was analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) methods. The compressive strength, density, thermal conductivity and porosity of the hardened specimens were evaluated as well. Research is being conducted with the material in question to create a cheap, particularly low-energy demanding building material. This material must have suitable mechanical properties for the structure and, at the same time, suitable thermal conductivity properties. It was determined that this porous concrete had compressive strength in the range of 2.12–7.95 MPa, density from 830 kg/m3 to 1142 kg/m3, and thermal conductivity in the range of 0.0985–0.2618 W/(m·K). The results indicate that the recommended content of phosphogypsum in alkali-activated material is 3–5% due to the optimal distribution of the mechanical and thermal properties and the conductivity. Alkali-activated slag and phosphogypsum material can be used in the manufacture of low-strength insulation blocks and to protect structures from the effects of high temperatures. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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17 pages, 7484 KiB  
Article
Post-Molding Shrinkage, Structure and Properties of Cellular Injection-Molded Polypropylene
by Artur Kościuszko, Mateusz Rojewski, Bartosz Nowinka and Filip Patalas
Materials 2022, 15(20), 7079; https://doi.org/10.3390/ma15207079 - 12 Oct 2022
Cited by 3 | Viewed by 1818
Abstract
Cellular injection molding is a common method of modifying polymer materials aimed at reducing the sink marks on moldings’ surfaces while reducing their weight. However, the dimensions of polypropylene (PP) samples as well as their mechanical properties after the injection molding process change [...] Read more.
Cellular injection molding is a common method of modifying polymer materials aimed at reducing the sink marks on moldings’ surfaces while reducing their weight. However, the dimensions of polypropylene (PP) samples as well as their mechanical properties after the injection molding process change as a result of re-crystallization. Knowledge of dimensional accuracy and awareness of the change in mechanical properties of products during conditioning are very important aspects in the polymer processing industry. The aim of this study was to assess the changes in the value of processing shrinkage and the size of the sink marks of porous PP moldings depending on the degree of porosity and the time since they were removed from the injection mold cavity. Studies of the structure and mechanical properties of moldings were carried out after several conditioning time intervals. The maximum conditioning time of samples was 840 h at 23 °C. Based on the analysis of the test results, it was found that the cellular injection molding process with the holding phase reduces the nucleation of gas pores, which results in a smaller reduction of sink marks than in the case of samples produced without the holding phase. However, PP moldings with a porosity degree equal to 8.9% were characterized by a higher shrinkage value after 1 h of conditioning, compared to moldings with porosity equal to 3.6%. The extension of the conditioning time also resulted in an increase in the value of linear shrinkage and the properties determined during tensile tests of solid and porous samples. Furthermore, in the case of samples with the highest porosity, the impact strength was reduced by about 30% after 840 h of conditioning compared to results obtained after 1 h. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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24 pages, 10419 KiB  
Article
Estimate of Coffin–Manson Curve Shift for the Porous Alloy AlSi9Cu3 Based on Numerical Simulations of a Porous Material Carried Out by Using the Taguchi Array
by Dejan Tomažinčič and Jernej Klemenc
Materials 2022, 15(6), 2269; https://doi.org/10.3390/ma15062269 - 18 Mar 2022
Cited by 2 | Viewed by 1739
Abstract
In real engineering applications, machine parts are rarely completely homogeneous; in most cases, there are at least some minor notch effects or even more extensive inhomogeneities, which cause critical local stress concentrations from which fatigue fractures develop. In the present research, a shift [...] Read more.
In real engineering applications, machine parts are rarely completely homogeneous; in most cases, there are at least some minor notch effects or even more extensive inhomogeneities, which cause critical local stress concentrations from which fatigue fractures develop. In the present research, a shift of the Coffin–Manson εaN material curve in a structure with random porosity subjected to dynamic LCF loads was studied. This allows the rest of the fatigue life prediction process to remain the same as if it were a homogeneous material. Apart from the cyclic σε curve, which is relatively easy to obtain experimentally, the εaN curve is the second most important curve to describe the correlation between the fatigue life N and the strain level εa. Therefore, the correct shift of the εaN curve of the homogeneous material to a position corresponding to the porous state of the material is crucial. We have found that the curve shift can be efficiently performed on the basis of numerical simulations of a combination of five porosity-specific geometric influences and the associated regression analysis. To model the modified synthetic εaN curve, five geometric influences of porosity by X-ray or μ-CT analysis are quantified, and then the porosity-adjusted coefficients of the Coffin–Manson equation are calculated. The proposed approach has been successfully applied to standard specimens with different porosity topography. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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14 pages, 7393 KiB  
Article
Mechanical Properties and Deformation Mechanisms of Graphene Foams with Bi-Modal Sheet Thickness by Coarse-Grained Molecular Dynamics Simulations
by Shenggui Liu, Mindong Lyu and Chao Wang
Materials 2021, 14(19), 5622; https://doi.org/10.3390/ma14195622 - 27 Sep 2021
Cited by 2 | Viewed by 1709
Abstract
Graphene foams (GrFs) have been widely used as structural and/or functional materials in many practical applications. They are always assembled by thin and thick graphene sheets with multiple thicknesses; however, the effect of this basic structural feature has been poorly understood by existing [...] Read more.
Graphene foams (GrFs) have been widely used as structural and/or functional materials in many practical applications. They are always assembled by thin and thick graphene sheets with multiple thicknesses; however, the effect of this basic structural feature has been poorly understood by existing theoretical models. Here, we propose a coarse-grained bi-modal GrF model composed of a mixture of 1-layer flexible and 8-layer stiff sheets to study the mechanical properties and deformation mechanisms based on the mesoscopic model of graphene sheets (Model. Simul. Mater. Sci. Eng. 2011, 19, 54003). It is found that the modulus increases almost linearly with an increased proportion of 8-layer sheets, which is well explained by the mixture rule; the strength decreases first and reaches the minimum value at a critical proportion of stiff sheets ~30%, which is well explained by the analysis of structural connectivity and deformation energy of bi-modal GrFs. Furthermore, high-stress regions are mainly dispersed in thick sheets, while large-strain areas mainly locate in thin ones. Both of them have a highly uneven distribution in GrFs due to the intrinsic heterogeneity in both structures and the mechanical properties of sheets. Moreover, the elastic recovery ability of GrFs can be enhanced by adding more thick sheets. These results should be helpful for us to understand and further guide the design of advanced GrF-based materials. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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21 pages, 8864 KiB  
Article
Investigation of the Relationship between Morphology and Thermal Conductivity of Powder Metallurgically Prepared Aluminium Foams
by Arun Gopinathan, Jaroslav Jerz, Jaroslav Kováčik and Tomáš Dvorák
Materials 2021, 14(13), 3623; https://doi.org/10.3390/ma14133623 - 29 Jun 2021
Cited by 10 | Viewed by 1895
Abstract
Among different promising solutions, coupling closed-cell aluminium foam composite panels prepared by a powder metallurgical method with pore walls interconnected by microcracks, with low thermal conductivity phase change materials (PCMs), is one of the effective ways of increasing thermal conductivity for better performance [...] Read more.
Among different promising solutions, coupling closed-cell aluminium foam composite panels prepared by a powder metallurgical method with pore walls interconnected by microcracks, with low thermal conductivity phase change materials (PCMs), is one of the effective ways of increasing thermal conductivity for better performance of thermal storage systems in buildings. The internal structure of the foam formation, related to the porosity which decides the heat transfer rate, plays a significant role in the thermal energy storage performance. The dependence of the heat transfer characteristics on the internal foam structure is studied numerically in this work. The foamable precursor of 99.7% pure aluminium powder mixed with 0.15 wt.% of foaming agent, TiH2 powder, was prepared by compacting, and extruded to a volume of 20 × 40 × 5 mm. Two aluminium foam samples of 40 × 40 × 5 mm were examined with apparent densities of 0.7415 g/cm3 and 1.62375 g/cm3. The internal porous structure of the aluminium foam samples was modelled using X-ray tomography slices through image processing techniques for finite element analysis. The obtained numerical results for the heat transfer rate and effective thermal conductivity of the developed surrogate models revealed the influence of porosity, struts, and the presence of pore walls in determining the heat flow in the internal structure of the foam. Additionally, it was found that the pore size and its distribution determine the uniform heat flow rate in the entire foamed structure. The numerical data were then validated against the analytical predictions of thermal conductivity based on various correlations. It has been found that the simplified models of Bruggemann and Russell and the parallel–series model can predict the excellent effective thermal conductivity results of the foam throughout the porosity range. The optimal internal foam structure was studied to explore the possibilities of using aluminium foam for PCM-based thermal storage applications. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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20 pages, 7175 KiB  
Article
Casein/Apricot Filler in the Production of Flame-Retardant Polyurethane Composites
by Sylwia Członka, Agnė Kairytė, Karolina Miedzińska and Anna Strąkowska
Materials 2021, 14(13), 3620; https://doi.org/10.3390/ma14133620 - 29 Jun 2021
Cited by 13 | Viewed by 2251
Abstract
Polyurethane (PUR) composites reinforced with 1, 2, and 5 wt.% of apricot filler modified with casein were synthesized in the following study. The impact of 1, 2, and 5 wt.% of casein/apricot filler on the cellular structure and physico-mechanical performances of reinforced PUR [...] Read more.
Polyurethane (PUR) composites reinforced with 1, 2, and 5 wt.% of apricot filler modified with casein were synthesized in the following study. The impact of 1, 2, and 5 wt.% of casein/apricot filler on the cellular structure and physico-mechanical performances of reinforced PUR composites were determined. It was found that the incorporation of 1 and 2 wt.% of casein/apricot filler resulted in the production of PUR composites with improved selected physical, thermal, and mechanical properties, while the addition of 5 wt.% of casein/apricot filler led to some deterioration of their physico-mechanical performance. The best results were obtained for PUR composites reinforced with 2 wt.% of casein/apricot filler. Those composites were characterized by a uniform structure and a high content of closed cells. Compared with the reference foam, the incorporation of 2 wt.% of casein/apricot filler resulted in improvement in compressive strength, flexural strength, impact strength, and dynamic mechanical properties—such as glass transition temperature and storage modulus. Most importantly, PUR composites showed better fire resistance and thermal stability due to the good thermal performance of casein. The main aim of this article is to determine the influence of the natural combination of the apricot filler and casein on the mechanical properties and flammability of the obtained composites. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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17 pages, 22155 KiB  
Article
Ni/Al-Hybrid Cellular Foams: An Interface Study by Combination of 3D-Phase Morphology Imaging, Microbeam Fracture Mechanics and In Situ Synchrotron Stress Analysis
by Jutta Luksch, Anne Jung, Christoph Pauly, Ralf Derr, Patrick Gruenewald, Marc Laub, Manuela Klaus, Christoph Genzel, Christian Motz, Frank Mücklich and Florian Schaefer
Materials 2021, 14(13), 3473; https://doi.org/10.3390/ma14133473 - 22 Jun 2021
Cited by 2 | Viewed by 1314
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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18 pages, 10349 KiB  
Article
Effect of Heat Treatment on the Microstructure and Performance of Cu Nanofoams Processed by Dealloying
by Jenő Gubicza, Péter Jenei, Gigap Han, Pham-Tran Hung, Youngseok Song, Dahye Park, Ábel Szabó, Csilla Kádár, Jae-Hun Kim and Heeman Choe
Materials 2021, 14(10), 2691; https://doi.org/10.3390/ma14102691 - 20 May 2021
Cited by 6 | Viewed by 2063
Abstract
Cu nanofoams are promising materials for a variety of applications, including anodes in high-performance lithium-ion batteries. The high specific surface area of these materials supports a high capacity and porous structure that helps accommodate volume expansion which occurs as batteries are charged. One [...] Read more.
Cu nanofoams are promising materials for a variety of applications, including anodes in high-performance lithium-ion batteries. The high specific surface area of these materials supports a high capacity and porous structure that helps accommodate volume expansion which occurs as batteries are charged. One of the most efficient methods to produce Cu nanofoams is the dealloying of Cu alloy precursors. This process often yields nanofoams that have low strength, thus requiring additional heat treatment to improve the mechanical properties of Cu foams. This paper provides the effects of heat treatment on the microstructures, mechanical properties, and electrochemical performance of Cu nanofoams. Annealing was conducted under both inert and oxidizing atmospheres. These studies ultimately reveal the underlying mechanisms of ligament coarsening during heat treatment. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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13 pages, 4038 KiB  
Article
Characterization of Open-Cell Sponges via Magnetic Resonance and X-ray Tomography
by Gabriele M. Cimmarusti, Abhishek Shastry, Matthieu N. Boone, Veerle Cnudde, Karl Braeckman, Anju D. M. Brooker, Eric S. J. Robles and Melanie M. Britton
Materials 2021, 14(9), 2187; https://doi.org/10.3390/ma14092187 - 24 Apr 2021
Cited by 2 | Viewed by 2206
Abstract
The applications of polymeric sponges are varied, ranging from cleaning and filtration to medical applications. The specific properties of polymeric foams, such as pore size and connectivity, are dependent on their constituent materials and production methods. Nuclear magnetic resonance imaging (MRI) and X-ray [...] Read more.
The applications of polymeric sponges are varied, ranging from cleaning and filtration to medical applications. The specific properties of polymeric foams, such as pore size and connectivity, are dependent on their constituent materials and production methods. Nuclear magnetic resonance imaging (MRI) and X-ray micro-computed tomography (µCT) offer complementary information about the structure and properties of porous media. In this study, we employed MRI, in combination with µCT, to characterize the structure of polymeric open-cell foam, and to determine how it changes upon compression, µCT was used to identify the morphology of the pores within sponge plugs, extracted from polyurethane open-cell sponges. MRI T2 relaxation maps and bulk T2 relaxation times measurements were performed for 7° dH water contained within the same polyurethane foams used for µCT. Magnetic resonance and µCT measurements were conducted on both uncompressed and 60% compressed sponge plugs. Compression was achieved using a graduated sample holder with plunger. A relationship between the average T2 relaxation time and maximum opening was observed, where smaller maximum openings were found to have a shorter T2 relaxation times. It was also found that upon compression, the average maximum opening of pores decreased. Average pore size ranges of 375–632 ± 1 µm, for uncompressed plugs, and 301–473 ± 1 µm, for compressed plugs, were observed. By determining maximum opening values and T2 relaxation times, it was observed that the pore structure varies between sponges within the same production batch, as well as even with a single sponge. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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Review

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24 pages, 4826 KiB  
Review
The Integration of Triboelectric Nanogenerators and Supercapacitors: The Key Role of Cellular Materials
by Jiajing Meng, Zequan Zhao, Xia Cao and Ning Wang
Materials 2023, 16(10), 3751; https://doi.org/10.3390/ma16103751 - 15 May 2023
Cited by 2 | Viewed by 1377
Abstract
The growing demand for sustainable and efficient energy harvesting and storage technologies has spurred interest in the integration of triboelectric nanogenerators (TENGs) with supercapacitors (SCs). This combination offers a promising solution for powering Internet of Things (IoT) devices and other low−power applications by [...] Read more.
The growing demand for sustainable and efficient energy harvesting and storage technologies has spurred interest in the integration of triboelectric nanogenerators (TENGs) with supercapacitors (SCs). This combination offers a promising solution for powering Internet of Things (IoT) devices and other low−power applications by utilizing ambient mechanical energy. Cellular materials, featuring unique structural characteristics such as high surface−to−volume ratios, mechanical compliance, and customizable properties, have emerged as essential components in this integration, enabling the improved performance and efficiency of TENG−SC systems. In this paper, we discuss the key role of cellular materials in enhancing TENG−SC systems’ performance through their influence on contact area, mechanical compliance, weight, and energy absorption. We highlight the benefits of cellular materials, including increased charge generation, optimized energy conversion efficiency, and adaptability to various mechanical sources. Furthermore, we explore the potential for lightweight, low−cost, and customizable cellular materials to expand the applicability of TENG−SC systems in wearable and portable devices. Finally, we examine the dual effect of cellular materials’ damping and energy absorption properties, emphasizing their potential to protect TENGs from damage and increase overall system efficiency. This comprehensive overview of the role of cellular materials in the integration of TENG−SC aims to provide insights into the development of next−generation sustainable energy harvesting and storage solutions for IoT and other low−power applications. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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