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1
Wang, Bin, Bugao Xu i Hejun Li. "Fabrication and properties of carbon/carbon-carbon foam composites". Textile Research Journal 89, nr 21-22 (13.03.2019): 4452–60. http://dx.doi.org/10.1177/0040517519836942.
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This paper was focused on the development of a new composite for high thermal insulation applications with carbon/carbon (C/C) composites, carbon foams and an interlayer of phenolic-based carbon. The microstructure, mechanical properties, fracture mechanism and thermal insulation performance of the composite was investigated. The experiment results showed that the bonding strength of the C/C-carbon foam composite was 4.31 MPa, and that the fracture occurred and propagated near the interface of the carbon foam and the phenolic-based carbon interlayer due to the relatively weak bonding. The shear load-displacement curves were characterized by alternated linear slopes and serrated plateaus before a final failure. he experiment revealed that the thermal conductivity of the C/C-carbon foam composite was 1.55 W·m−1ċK−1 in 800℃, which was 95.8% lower than that of C/C composites, proving that the thermal insulation of the new foam composite was greatly enhanced by the carbon foam with its porous hollow microstructure.
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Kishimoto, Akira, Takahiro Nakagawa, Takashi Teranishi i Hidetaka Hayashi. "Superplastically Foaming Method for Reliable Porous Ceramics". Materials Science Forum 735 (grudzień 2012): 109–12. http://dx.doi.org/10.4028/www.scientific.net/msf.735.109.
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Porous ceramics incorporates pores to improve several properties including thermal insulation, maintaining inherent ceramic properties such as corrosion resistance and large mechanical strength. Conventional porous ceramics is usually fabricated through an insufficient sintering, leading to degraded strength and durability. Contrary to this, we have innovated superplastically foaming method to make ceramic foam only in the solid state. In this method, the previously inserted foam agent evaporates after the full densification of matrix at around the sintering temperature. Closed pores expand utilizing the superplastic deformation driven by the evolved gas pressure. Based on this concept we fabricated 8mol% yttria stabirized zirconia based porous ceramics and examined the properties concerning the high temperature structural material with thermal insulation.
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Ahn, Jae Hyeok, Jeong Hyeon Kim, Jeong Dae Kim, Seul Kee Kim, Kang Hyun Park, Sung Kyun Park i Jae Myung Lee. "Enhancement of Mechanical and Thermal Characteristics of Polyurethane-Based Composite with Silica Aerogel". Materials Science Forum 951 (kwiecień 2019): 63–67. http://dx.doi.org/10.4028/www.scientific.net/msf.951.63.
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Synthesis of polyurethane foams (PUF) with silica aerogel nanoparticles is an efficient alternative to improve the mechanical and thermal properties of the foam owing to the outstanding thermal insulation properties of porous silica aerogel nanoparticles. Silica aerogel was added into polyurethane foams at different weight percent (0, 1, 3, 5 wt.%) to observe the changes in the material properties. To confirm the applicability of the synthesized PUF to the heat insulating material, compressive tests were carried out at ambient and cryogenic temperature (20, -163°C) and the thermal conductivities were measured according to wt.%. In addition, the cell microstructure was identified using FE-SEM to analyze the effect of silica aerogels on the foam morphologies. As a result of the experiment, it was confirmed that the mechanical strength and the heat insulation performance were improved in the polyurethane foam containing 1 wt.% of silica aerogel.
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Lin, Ya Mei, Cui Wei Li, Feng Kun Yang i Chang An Wang. "Fabrication and Properties of Porous Anorthite⁄Mullite Ceramics". Key Engineering Materials 512-515 (czerwiec 2012): 590–95. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.590.
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Porous anorthite/mullite composite ceramics with different mullite content were fabricated by foam-gelcasting, using CaCO3, SiO2, α-Al2O3as raw material for anorthite phase and mullite powder for mullite phase. Effects of mullite powder content on bulk density, porosity, compressive strength and thermal conductivity of the porous composite ceramics were researched. It has been shown that mullite powder content has great effect on microstructure and properties of the porous anorthite⁄mullite composite ceramics. The open porosity of the prepared porous anorthite⁄mullite composite ceramics is in the range of 58.7 %~77.5 %, the compressive strength is between 4.2 and 30.9 MPa, and the thermal conductivity is in the range of 0.18 ~1.47 W⁄(m·K).
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Deptulski, Rafael, Gisele Vieira i Rachid Bennacer. "Active wall through a porous media foam type: flow and transfer characterization". MATEC Web of Conferences 330 (2020): 01052. http://dx.doi.org/10.1051/matecconf/202033001052.
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Despite the efforts to develop new solutions to achieve the objectives of positive buildings in energy, a few studies in this area has been performed using a porous media foam type. The aim of this paper is to present the behaviour transfers of flow through a multi-structured porous media and to achieve the influence of the porosity and the thermal conductivity properties of the skeletal phase, and the interaction with a cross flow in order to get the equivalent of a perfect insulator. Therefore, in a specially made device, a finite volume method was applied to study a flow through a porous media foam-type, which was simulated to characterize the properties of the equivalent medium in terms of permeability and thermal conductivity. The analysis demonstrates that the solid phase composition and the medium porosity, as well as the distribution of pore size, are preponderant characteristics to constitute a foam structured media. Furthermore, the thermal boundary layer given by a forced convection through the porous medium has demonstrated the important influence of the flow phenomenon in a thermodynamic coupling. Lastly, three optimum configurations for the construction envisaging a balance of depleted thermal and dynamic powers for a relative conductivity *=10 were found between the velocity 2 10-3 (m/s) and 4 10-3 (m/s).
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Mashkin, Nikolay, Ekaterina Bartenjeva i Rustam Mansurov. "Naturally cured foamed concrete with improved thermal insulation properties". MATEC Web of Conferences 143 (2018): 02005. http://dx.doi.org/10.1051/matecconf/201814302005.
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The paper is dedicated to investigation on improvement of thermal insulation properties of non-autoclaved concrete by increasing aggregate stability of foamed concrete mixture. The study demonstrates influence of mineral admixtures on the foam stability index in the mortar mixture and on decrease of foamed concrete density and thermal conductivity. The effect of mineral admixtures on thermal conductivity properties of non-autoclaved concrete was assessed through different ways of their addition: to the foam and to the mortar mixture. The admixtures were milled up to the specific surface area of 300 and 600 m2/kg using an AГO-9 centrifugal attrition mill with continuous operation mode (Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk). Laboratory turbulent foam concrete mixer was used to prepare foamed concrete. Thermal conductivity coefficient was defined by a quick method using “ИTП-MГ 4 “Zond” thermal conductivity meter in accordance with the regulatory documents. The impact of modifiers on the foam structure stability was defined using the foam stability index for the mortar mixture. The research demonstrated the increase in stability of porous structure of non-autoclaved concrete when adding wollastonite and diopside. Improvement of thermal and physical properties was demonstrated, the decrease of thermal conductivity coefficient reaches 0.069 W/(m×°C)
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Mohd Razali, Razmi Noh, Bulan Abdullah, Muhammad Hussain Ismail i Norhamidi Muhamad. "Characteristic of Modified Geometrical Open-Cell Aluminum Foam by Casting Replication Process". Materials Science Forum 846 (marzec 2016): 37–41. http://dx.doi.org/10.4028/www.scientific.net/msf.846.37.
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In this work, aluminium foams with modified geometry were successfully fabricated with a combination of dense and porous structure The main objective of this study were to determine the initial physical properties of aluminium foam with modified geometry in terms of density, porosity and morphology. Three different NaCl space holder sizes ranging from 1 mm to 3 mm were sieved and used to replicate the final pore size of aluminium foam. The samples were successfully produced through casting replication process. After densification, samples underwent water leaching in ultrasonic bath to remove completely the space holder. Results showed that porosity of the aluminium foam increased from 50 – 62% when the size of space holder was increased from 1 mm to 3 mm. The morphology showed clearly an integrated modified geometry between dense and inter-connected porous structure which is beneficial for applications that require combination properties of structural, thermal and mechanical properties.
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Barteneva, Ekaterina A., Mikhail A. Ylesin, Nikolay A. Mashin i Dmitry V. Dubrov. "Improvement of Heat-Insulating Properties of Foam Concrete by Means of Mineral Additives". Key Engineering Materials 771 (czerwiec 2018): 31–36. http://dx.doi.org/10.4028/www.scientific.net/kem.771.31.
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Foam concrete solidifying in natural conditions significantly shrinks, which causes deterioration of the porous structure and thus the increase in the heat conductivity of the material. One of the solutions for this problem is application of mineral modifiers. As the mineral modifiers the authors used the production waste – mineral additives (wollastonite, diopside) at natural dispersive capacity, as well as milled down to 300 and 600 m2/kg of specific surface. The application of perlite microspheres in foam concrete was investigated. The thermal conductivity coefficient was defined by rapid method. The optimal composition of the mixture for manufacturing foam concrete products with mineral additives ensures the decrease in the heat conductivity coefficient by 41-43% compared to the reference composition. At complete replacement of fly-ash aggregate by perlite microspheres the thermal conductivity coefficient decreases down to 0.062 W/ (m×°С). The economic effect of application of the developed foam concrete with the additive of wollastonite and diopside compared with the foam concrete presented on the market is equal to 259 / 388 RUB/m2 of an erected structure at the density of D300/ D400 respectively. Thus, directed regulation of the porous structure of cellular concrete leads to significant improvement of stability of the foam concrete mixture, which makes the prerequisites to the decrease in the thermal conductivity of the material and positive technical and economical results.
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Adamek, Grzegorz, Mikolaj Kozlowski, Mieczyslawa Jurczyk, Przemyslaw Wirstlein, Jakub Zurawski i Jaroslaw Jakubowicz. "Formation and Properties of Biomedical Ti-Ta Foams Prepared from Nanoprecursors by Thermal Dealloying Process". Materials 12, nr 17 (22.08.2019): 2668. http://dx.doi.org/10.3390/ma12172668.
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The paper presents a promising method of preparation of titanium-based foams by the thermal dealloying method. The first step of this study was the Ti-Ta-Mg based nanopowder preparation using the mechanical alloying (MA) process performed at room temperature. The next step was forming the green compacts by cold pressing and then sintering with magnesium dealloying from the titanium-based alloy structure. The mechanism of the porous structure formation was based on the removal of magnesium from the titanium alloy at a temperature higher than the boiling point of magnesium (1090 °C). The influence of the Mg content on the formation of the porous Ti-30Ta foam has been investigated. The sintering stage was performed in vacuum. During the dealloying process, the magnesium atoms diffuse from the middle to the surface of the sample and combine to form vapors and then evaporate leaving pores surrounded by the metallic scaffold. The porosity, the mechanical properties as well as biocompatibility have been investigated. The titanium-based foam of high porosity (up to 76%) and the pore size distribution from nano- to micro-scale have been successfully prepared. For the medical applications, the Ti-Ta metallic foams have shown a positive behavior in the MTT test. The as-shown results clearly exhibit a great potential for thermal dealloying in the preparation of porous structures.
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Kim, B., P. Nun-anan, K. Hancharoen, K. Seiichi i K. Boonkerd. "Effect of Type and Content of Blowing Agent on Properties of NR/EPDM/EVA Foam". Journal of Physics: Conference Series 2175, nr 1 (1.01.2022): 012018. http://dx.doi.org/10.1088/1742-6596/2175/1/012018.
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Abstract This research aimed to study the influence of type and content of blowing agents on the properties of rubber foam NR/EPDM/EVA. Supercell DP, supercell RC 720, and EW5 were used here as a blowing agent. The content of the blowing agent was varied from 3 phr to 4 and 5 phr. The results showed that supercell RC 720 and OBSH were not suitable for this trinary rubber foam due to the absence of even porous structure, while the supercell DP gave the even porous structure throughout the sample and the lowest density. It was found that increasing supercell DP loading led to the increase in pore size, thermal conductivity but the decrease in the density, tensile strength, and elastic recovery of rubber foam. Owing to the lowest thermal conductivity, it can be inferred here that supercell DP at 5 phr was suitable to produce rubber foam from NR blended with EPDM and EVA for a ceiling board application.
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Han, Tian-Long, Bi-Fan Guo, Guo-Dong Zhang i Long-Cheng Tang. "Facile Synthesis of Hollow Glass Microsphere Filled PDMS Foam Composites with Exceptional Lightweight, Mechanical Flexibility, and Thermal Insulating Property". Molecules 28, nr 6 (13.03.2023): 2614. http://dx.doi.org/10.3390/molecules28062614.
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The feature of low-density and thermal insulation properties of polydimethylsiloxane (PDMS) foam is one of the important challenges of the silicone industry seeking to make these products more competitive compared to traditional polymer foams. Herein, we report a green, simple, and low-cost strategy for synthesizing ultra-low-density porous silicone composite materials via Si-H cross-linking and foaming chemistry, and the sialylation-modified hollow glass microspheres (m-HM) were used to promote the HM/PDMS compatibility. Typically, the presence of 7.5 wt% m-HM decreases the density of pure foam from 135 mg/cm−3 to 104 mg/cm−3 without affecting the foaming reaction between Si-H and Si-OH and produces a stable porous structure. The optimized m-HM-modified PDMS foam composites showed excellent mechanical flexibility (unchanged maximum stress values at a strain of 70% after 100 compressive cycles) and good thermal insulation (from 150.0 °C to 52.1 °C for the sample with ~20 mm thickness). Our results suggest that the use of hollow microparticles is an effective strategy for fabricating lightweight, mechanically flexible, and thermal insulation PDMS foam composite materials for many potential applications.
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Pavlenko, Anatoliy, Hanna Koshlak i Anna Maria Slowak. "The use of the ash of thermal power plants for the production of efficient porous insulation". E3S Web of Conferences 86 (2019): 00003. http://dx.doi.org/10.1051/e3sconf/20198600003.
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The article presents the results of research related to the use of ash from thermal power plants for the production of porous heat insulating materials. Using the method of differential - thermal analysis, the optimal values of the composition of the raw mix and the thermal regimes of the formation of the porous structure were found. It is shown that it is possible to obtain a new ash-based binder and thus replace up to 70% of cement in the production of thermal insulationthe properties of the new material are similar to the properties of foam concrete.
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Cherunova, I., N. Kornev i Mathias Paschen. "Study of Compression Soft Porous Foam Materials". Solid State Phenomena 265 (wrzesień 2017): 279–83. http://dx.doi.org/10.4028/www.scientific.net/ssp.265.279.
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The paper presents the findings of the research into neoprene-like soft foamed materials during compression in water. The specific features of the internal structure of such materials lead to complex deformations. This is related to the specific features of the internal structure of materials that contain a large amount of inert air. The paper also presents the findings of structural studies which explained the relationship between the elastic properties of materials and the strength of polymer bonds forming internal air cavities. When foamed the polymer sections are destroyed under compression, it results in the loss of enclosed volume of air voids. This changes the total volume and thickness of the material, which defines some physical and thermal properties of products made of such material. Hydrostatic pressure environments have their own specific features. Rheological properties of soft polymers in a hydrostatic pressure environment give rise to a composite effect of compression deformation. The study of recent developments in the research into polymer deformations in a hydrostatic pressure environment shows that it is difficult to record the stages of reversible and nonreversible compression deformation in near-real experimental simulation of diving operations. The paper presents the developments and findings of experimental design studies for a product (wetsuit) made of foamed materials that were conducted in a hydrostatic pressure environment in an enclosed volume using special Drucktank equipment by the Marine Engineering Department of the University of Rostock
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Yousry, Yasmin Mohamed, Eleftherios Christos Statharas, Kui Yao, Ayman Mahmoud Mohamed, Poh Chong Lim i Francis Eng Hock Tay. "Sound Absorption Improvement in Porous Ferroelectret Polyethylene with Effective Piezoelectric Mechanism". Polymers 14, nr 22 (10.11.2022): 4843. http://dx.doi.org/10.3390/polym14224843.
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Airborne sound absorption in porous materials involves complex mechanisms of converting mechanical acoustic energy into heat. In this work, the effective piezoelectric properties of polyethylene ferroelectret foams on sound absorption were investigated by comparable samples with and without the piezoelectric response. Corona poling and thermal annealing treatments were applied to the samples in order to enable and remove the piezoelectric property, respectively, while the microstructure and the mechanical properties remained substantially unchanged. The effective piezoelectric properties and airborne sound absorption coefficients of the polyethylene foam samples before and after material treatments were measured and analyzed. Our experimental results and theoretical analysis showed that the open-cell ferroelectret polymer foam with an effective piezoelectric property provides an additional electromechanical energy conversion mechanism to enhance the airborne acoustic absorption performance.
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Myalski, Jerzy, Bartosz Hekner i Andrzej Posmyk. "The influence of glassy carbon on tribological properties in metal – ceramic composites with skeleton reinforcement". Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2015, CICMT (1.09.2015): 000121–24. http://dx.doi.org/10.4071/cicmt-tp44.
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This paper presents a results of mechanical and tribological properties of aluminum based composites with skeleton reinforcement. The aluminum alloy based composites were produced using pressure infiltration process. As a reinforcement ceramic foam with opened cells was applied. This reinforcement structure give an opportunity to limit the most common defects (like agglomeration, inhomogeneity, ect.) occurring in composite materials obtained by casting. In presented research three different types of porous foam were analysed. There were alumina foam covered by thin glassy carbon layer (Al2O3 – GC) and two types of glassy carbon foams (GC). Due to application of porous ceramic foam, an increasing of composite mechanical properties are expected. An additional glassy carbon layer with thickness up to 5 μm was applied for increasing a thermal conductivity and rapid heat dissipation from the material. Moreover, the skeleton structure of glassy carbon, and its wear mechanism, should decrease a friction coefficient value. Two manufactured types of composites: Al2O3 – GC foam and own produced glassy carbon foam were compared with material reinforced by spatial carbon structure obtained from commercial RVC (produced by Reynolds) foam. The results showed that the application of porous ceramic and ceramic – carbon reinforcement skeletons led to increasing of mechanical properties of composite. The conducted research using pin–on–disc method, with 2,5 MPa of load and 1,0 m/s of speed revealed that glassy carbon have significant influence on decreasing friction coefficient and wear rate. An analysis of material external layer in areas after coupling with pin (wear track) indicated a fragmentation of glassy carbon foam. The wear products are not remove from friction surfaces, but these products create thin carbon film with lubricant properties. The conducted research showed both, a possibility to produce composites with skeleton structure of reinforcement and a possibility of correction of material tribological properties using glassy carbon.
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Chen, Yiqi, Yujie Duan, Han Zhao, Kelan Liu, Yiqing Liu, Min Wu i Peng Lu. "Preparation of Bio-Based Foams with a Uniform Pore Structure by Nanocellulose/Nisin/Waterborne-Polyurethane-Stabilized Pickering Emulsion". Polymers 14, nr 23 (27.11.2022): 5159. http://dx.doi.org/10.3390/polym14235159.
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Bio-based porous materials can reduce energy consumption and environmental impact, and they have a possible application as packaging materials. In this study, a bio-based porous foam was prepared by using a Pickering emulsion as a template. Nisin and waterborne polyurethane (WPU) were used for physical modification of 2,2,6,6-tetramethyl piperidine-1-oxyl-oxidized cellulose nanocrystals (TOCNC). The obtained composite particles were applied as stabilizers for acrylated epoxidized soybean oil (AESO) Pickering emulsion. The stability of the emulsion was characterized by determination of the rheological properties and microscopic morphology of the emulsion. The emulsion stabilized by composite particles showed better stability compared to case when TOCNC were used. The porous foam was obtained by heating a composite-particles-stabilized Pickering emulsion at 90 °C for 2 h. SEM (scanning electron microscopy) images showed that the prepared foam had uniformly distributed pores. In addition, the thermal conductivity of the foam was 0.33 W/m·k, which was a significant decrease compared to the 3.92 W/m·k of the TOCNC foam. The introduction of nisin and WPU can reduce the thermal conductivity of the foam, and the physically modified, TOCNC-stabilized Pickering emulsion provides an effective means to preparing bio-based porous materials.
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Gnip, Ivan, Vladislovas Keršulis i Antanas Laukaitis. "BEAUTOKLAVIO PUTBETONIO ŠILUMINIŲ TECHNINIŲ SAVYBIŲ TYRIMAI/INVESTIGATION INTO NON-AUTOCLAVED FOAM CONCRETE HEAT ENGINEERING PROPERTIES". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 2, nr 8 (31.12.1996): 60–66. http://dx.doi.org/10.3846/13921525.1996.10590173.
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The purpose of this investigation was to determine various density foam concrete heat engineering properties. These properties are not included in valid construction standards [1]. Thermal conductivity of samples was determined at 25°C according to [2], specific heat—[3], vapour permeability—[4] and sorption moisture—[5]. Dry foam concrete thermal conductivity (W/m-K) dependency on its density is given in Fig. 1 as well as after mathematical statistical treatment using the regressive equation [1]. Foam concrete thermal conductivity dependency on its humidity statistical analysis results is given in Table 1, here ΔλW s and ΔλW t is the average absolute thermal conductivity increase for 1% materials moisture according to mass and volume, while and δW s δW t is the same increase, but in percentage value. Foam concrete thermal conductivity dependency on moisture is linear. The specific heat value for 245 and 840 kg/m3 density foam concrete is 980±50 and 850±50 J/kg·K respectively. The determined foam concrete sorption moisture is given in Fig. 2 and Table 2. The steep moisture increase at high ambient air humidity is defined by adsorption and the beginning of capillary condensation. This state is not noted in literature curve 2 [7] and evidently due to the short experimental interval. The vapour permeability results for foam concrete are given in Fig. 3 and using the regressive equation (2). Our results are approximately 13% lower than those given for porous concrete [1]. The calculated thermal conductivity was determined using equation (3), assuming that the sorbtion moisture is equal to the relative air humidity (80–85)% (Table 2). Then 250, 500 and 800 kg/m3 density foam concrete λ(ρ0, Wsk) is equal to 0,12, 0,19 and 0,32 W/m·K respectively. The foam concrete heat capacity coefficients S, calculated according to formula (4) for temperature fluctuation period z=24 h and according to damp foam concrete density and specific heat are given in Table 3. Experimental for 260, 500 and 800 kg/m3 density non-autoclaved foam concrete heat engineering values are given in Table 4. For comparison, the denominators (under the line) show the corresponding values for porous concrete given in [1], It is purposive to use in practical calculation specific non-autoclaved foam concrete heat engineering values because these differences are substantial.
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Yang, Feng Kun, Cui Wei Li, Ya Mei Lin i Chan Gan Wang. "Fabrication of Porous Mullite Ceramics with High Porosity Using Foam-Gelcasting". Key Engineering Materials 512-515 (czerwiec 2012): 580–85. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.580.
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In this paper, porous mullite ceramics with an apparent porosity up to 81 % were fabricated by foam-gelcasting using mullite powder as raw material with solid loading of 40 vol.%. The monomers content and sitering temperature have obvious effect on the properties of porous mullite ceramics. The apparent porosity of the prepared samples was in the range of 75~82%, compressive strength, was in the range of 3.0~16.02 MPa, and thermal conductivity was between 0.14 and 0.47 W/(m•K). A complex porous microstructure was formed, where large spherical pores contained small cellular pores on their internal walls.
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Paunescu, Lucian, Sorin Mircea Axinte, Marius Florin Dragoescu i Felicia Cosmulescu. "Adequate Correlation between the Physical and Mechanical Properties of Glass Foam". Journal La Multiapp 2, nr 4 (27.09.2021): 14–26. http://dx.doi.org/10.37899/journallamultiapp.v2i4.415.
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The paper presents experimental results obtained in the manufacturing process of a glass foam by adequate correlation between its physical and thermal properties (density, porosity, thermal conductivity) and mechanical (compressive strength) by a slight controlled overheating of the foamed material. Using a powder mixture of glass waste (87-91.5 %), coal fly ash (3-9 %) and silicon carbide (4-5.5 %) microwave heated at 935-975 ºC by this unconventional technique, constituting the originality of the work, was obtained a glass-ceramic foam with moderate compressive strength (1.8-2.6 MPa) and very low thermal conductivity (0.058-0.070 W/m·K). The material overheating generated a homogeneous porous structure characterized by closed cells with relatively large dimensions (without the tendency to join neighboring cells) making it difficult to transfer heat across the material. The foamed product is suitable for the manufacture of thermal insulation blocks for the inner or outer walls of the building without excessive mechanical stress, being an advantageous alternative by comparison with known types of polymeric or fiberglass thermal insulation materials.
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Paunescu, Lucian, Sorin Mircea Axinte, Marius Florin Dragoescu i Felicia Cosmulescu. "Adequate Correlation between the Physical and Mechanical Properties of Glass Foam". Journal La Multiapp 1, nr 4 (27.09.2021): 14–26. http://dx.doi.org/10.37899/journallamultiapp.v1i4.415.
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The paper presents experimental results obtained in the manufacturing process of a glass foam by adequate correlation between its physical and thermal properties (density, porosity, thermal conductivity) and mechanical (compressive strength) by a slight controlled overheating of the foamed material. Using a powder mixture of glass waste (87-91.5 %), coal fly ash (3-9 %) and silicon carbide (4-5.5 %) microwave heated at 935-975 ºC by this unconventional technique, constituting the originality of the work, was obtained a glass-ceramic foam with moderate compressive strength (1.8-2.6 MPa) and very low thermal conductivity (0.058-0.070 W/m·K). The material overheating generated a homogeneous porous structure characterized by closed cells with relatively large dimensions (without the tendency to join neighboring cells) making it difficult to transfer heat across the material. The foamed product is suitable for the manufacture of thermal insulation blocks for the inner or outer walls of the building without excessive mechanical stress, being an advantageous alternative by comparison with known types of polymeric or fiberglass thermal insulation materials.
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Saljooghi, Milad, Younes Bakhshan, Saeid Niazi i Jamshid Khorshidi. "Experimental and numerical investigation on the effective thermal conductivity of stochastic structure". Materials Express 9, nr 8 (1.11.2019): 861–71. http://dx.doi.org/10.1166/mex.2019.1566.
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The Conception of thermo-physical properties of porous materials is a challenging task for scientists to conquer. The open cell metal foam increases heat transfer while energy dissipation, dimension and density of them which are constraints for modern technologies significantly reduce. In the present study, the open cell metal foams with four kinds of structures have been investigated numerically and experimentally and the effective thermal conductivity (ETC) of them have been extracted with using different base fluids such as water, air and paraffin. Also, various metals have been considered copper, aluminum, nickel and silver. Finally, a validated correlation for calculation of ETC of open cell metal foams has been developed which is function of thermal conductivity of fluid and metal, porosity and geometrical properties of pore that is applicable for all open cell metal foam approximately. The results show, good agreements between the modeling results and experimental data.
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Merillas, Beatriz, Alyne Lamy-Mendes, Fernando Villafañe, Luisa Durães i Miguel Ángel Rodríguez-Pérez. "Silica-Based Aerogel Composites Reinforced with Reticulated Polyurethane Foams: Thermal and Mechanical Properties". Gels 8, nr 7 (21.06.2022): 392. http://dx.doi.org/10.3390/gels8070392.
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In this work, silica aerogel composites reinforced with reticulated polyurethane (PU) foams have been manufactured having densities in the range from 117 to 266 kg/m3 and porosities between 85.7 and 92.3%. Two different drying processes were employed (ambient pressure drying and supercritical drying) and a surface modification step was applied to some of the silica formulations. These composites, together with the reference PU foam and the monolithic silica aerogels, were fully characterized in terms of their textural properties, mechanical properties and thermal conductivities. The surface modification with hexamethyldisilazane (HMDZ) proved to improve the cohesion between the reticulated foam and the silica aerogels, giving rise to a continuous network of aerogel reinforced by a polyurethane porous structure. The samples dried under supercritical conditions showed the best interaction between matrixes as well as mechanical and insulating properties. These samples present better mechanical properties than the monolithic aerogels having a higher elastic modulus (from 130 to 450 kPa), a really exceptional flexibility and resilience, and the capacity of being deformed without breaking. Moreover, these silica aerogel-polyurethane foam (Sil-PU) composites showed an excellent insulating capacity, reaching thermal conductivities as low as 14 mW/(m·K).
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Zhou, Yun, Zeng Chuan Hong, Xiang Ping Ai i Xiao Qing Zuo. "Manufacture, Structure and Properties of Copper Foams". Advanced Materials Research 652-654 (styczeń 2013): 1163–66. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.1163.
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The raw materials used for manufacturing copper foams are the metal and a carbonate in powder form. Copper foams are fabricated by mixing metal and carbonate powder, sintering, and removing carbonate processing. The effect of Cu particle size, compacting pressure on the porosity of porous samples are analyzed. With SEM and EDS, particles binding and microstructure evolution during sintering are studied, and the mechanical properties of porous samples are measured. Results show that copper foams with the porosity of 60 % ~85 % are successfully prepared, pore size 50~1000㎛.The porosity of copper foams decreases with the pressure increasing and copper particle size decreasing at same volume fraction of copper powder . The compressive strength of copper foams decreases with the porosity raising, for the copper foam of 80% porosity, the compressive strength up to 20-30Mpa.The electrical conductivity of copper foams decreases with porosity increasing. Thermal expansion coefficient α of copper foams increases from 17 to 19*10-6 .K-1 when temperature rising from 50°C to 100°C.
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Saikrasoon, Anut, Sirithan Jiemsirilers i Pitak Laoratanakul. "Influence of Alkaline Concentration on Physical Properties of Porous Geopolymer Using Silica Fume as Foaming Agent ". Key Engineering Materials 659 (sierpień 2015): 106–10. http://dx.doi.org/10.4028/www.scientific.net/kem.659.106.
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Porous geopolymer could be synthesized by using metakaolin and silica fume as foaming agent. The foam morphology was estimated in the function of water, silica fume content, and curing temperatures. Raw materials were mixed by Hobart mixer for 5 minutes and then poured in to cylinder mold after that cured at 70 degree celsius for 24 hours. During the synthesis process, the complex reaction would occur such as polycondensation and oxidation. These reactions affect to chemical and physical properties of porous sample. The parameters that mention above affect to density, physical, and chemical properties. The thermal conductivity of porous geopolymer that contained with 14 molal NaOH concentration yield the lowest values of 0.5101 W/mK and pore size distribution of 0.01-0.8 mm.Keywords: Porous geopolymer, thermal conductivity, metakaolin
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Keasangam, Neatithorn, Jirasuta Chungprempree, Jitima Preechawong, Manit Nithitanakul i Pornsri Sapsrithong. "Acid-Activated Organobentonite-Based Highly Porous Foams via Polymerized High Internal Phase Emulsion: Preparation, Characterization and Machine Learning Prediction". Materials Science Forum 1086 (27.04.2023): 27–34. http://dx.doi.org/10.4028/p-8zj010.
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Preparation, characterization, and machine learning prediction of characteristics of acid-treated organobentonite-based highly porous foams via polymerized high internal phase emulsion were reported in this work. The effect of acid-treated organobentonite (AC-BTN) as an inorganic filler on the properties of poly(DVB)HIPE porous foam was experimentally investigated. Incorporating AC-BTN into the continuous phase of the high internal phase emulsion would improve thermal and mechanical properties and also increase the surface area of the resulting materials when compared to the unfilled poly(DVB)HIPE foam. Various amounts of AC-BTN, i.e., 0, 1, 3, 5, 7, and 10 wt.% of AC-BTN, were incorporated into the continuous phase to enhance the properties of poly(DVB)HIPE foam. The surface area and the degradation temperatures (Td) for the series of poly(DVB)HIPE foam filled with AC-BTN increased with increasing filler content from 0 to 10 wt.%. The maximum improvement of mechanical properties was found with the addition of 5 wt.% of AC-BTN into the continuous phase of poly(DVB)HIPE foam. Moreover, the adsorption of CO2 gas by poly(DVB)HIPE foam filled with AC-BTN was found to increase as well. It has been demonstrated in this study that the adsorption of CO2 by poly(DVB)HIPE foam filled with AC-BTN increased by 127% (from 0.00295 to 0.00670 mol/g) compared with neat poly(DVB)HIPE foam. Additionally, the machine learning (ML) method with a linear regression algorithm was employed for the characterization of poly(DVB)HIPE foam and the prediction of properties according to composite composition. Surface area, pore volume, Td, compressive stress, and Young’s modulus were evaluated. The accuracy of prediction using a machine learning application with a linear regression model for properties of poly(DVB)HIPE foam filled with AC-BTN was also reported.
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Zach, Jiri, Martin Sedlmajer, Jan Bubenik i Vitezslav Novak. "Utilization of Non-Traditional Fibers for Light Weight Concrete Production". Key Engineering Materials 760 (styczeń 2018): 231–36. http://dx.doi.org/10.4028/www.scientific.net/kem.760.231.
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Along with energy savings for heating and cooling, the demand for thermal insulation materials is increasing and is an attempt to achieve good thermal insulation properties for some of the construction materials. In the field of porous and lightweight concrete, this is e.g. concrete for foundations, concrete for floor constructions or flat roofs. The problem with these concrete is a relatively rapid drop in mechanical properties in reducing bulk density, with using conventional silicate binders, especially in the area below 1000 kg/m3. The paper describes the possibility of using recycled organic fibers in combination with lightweight aggregates based on foam glass for the production of porous and lightweight concrete with a good ratio of mechanical and thermal insulation properties.
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Sedlmajer, Martin, Jiří Zach i Jan Bubeník. "USING SECONDARY RAW MATERIALS IN LIGHTWEIGHT OPEN-STRUCTURE CONCRETE WITH GOOD UTILITY PROPERTIES". Acta Polytechnica CTU Proceedings 22 (25.07.2019): 94–98. http://dx.doi.org/10.14311/app.2019.22.0094.
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The paper presents the results of research in lightweight concrete with open structure made using a lightweight porous foam-glass aggregate produced from recycled glass powder. The goal was to develop lightweight concrete. In order to achieve the best possible properties while reducing binder content, the concrete was reinforced with by-product fibres, which helped reduce the weight of the concrete while delivering satisfactory mechanical properties. In the paper are proposed lightweight concrete with open structure made using foam-glass aggregate. Mechanical, thermal-insulating and acoustic properties were determined on lightweight concrete. Designed concrete is only made of crushed lightweight foam-glass aggregate with a combination of Portland cement with the option of adding recycled PET fibres. The new concretes possess a very good ratio of thermal insulation to mechanical properties as well as good sound absorption.
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Shioura, Naoto, Kazuki Matsushima, Tomoki Osato, Tomonaga Ueno, Norifumi Isu, Takeshi Hashimoto i Takumi Yana. "Fabrication and Characterization of Porous Silica/Carbon Nanotube Composite Insulation". MRS Advances 5, nr 33-34 (2020): 1791–98. http://dx.doi.org/10.1557/adv.2020.252.
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AbstractIn recent years, the demand for high performance thermal insulations has increased. While foam and aerogels have been researched for high performance thermal insulation, novel material design is required for further improvement. A porous silica has been found to have the potential to form a new thermal insulation material. However, porous silica is a powder and is difficult to form the porous compact. Therefore, we propose a composite insulation of powdered porous silica (p-SiO2), carbon nanotubes (CNTs) and sodium carboxy methyl cellulose (CMC). The fine voids and bulky structure of p-SiO2 greatly suppress gas and solid heat transfer. The composite of CNT can improve the moldability and enhance the mechanical properties. The moldability of thermal insulating materials improved even with the addition of 1 wt% CNT. With the addition of 1 wt% CNT, the increase in thermal conductivity was less than 0.01 W⋅m-1⋅K-1.
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Merillas, Beatriz, Fernando Villafañe i Miguel Ángel Rodríguez-Pérez. "Improving the Insulating Capacity of Polyurethane Foams through Polyurethane Aerogel Inclusion: From Insulation to Superinsulation". Nanomaterials 12, nr 13 (29.06.2022): 2232. http://dx.doi.org/10.3390/nano12132232.
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A novel synthesis of polyurethane foam/polyurethane aerogel (PUF–PUA) composites is presented. Three different polyurethane reticulated foams which present the same density but different pore sizes (named S for small, M for medium, and L for large) have been used. After the characterization of the reference materials (either, foams, and pure aerogel), the obtained composites have been characterized in order to study the effect of the foam pore size on the final properties, so that density, shrinkage, porous structure, mechanical properties, and thermal conductivity are determined. A clear influence of the pore size on the density and shrinkage was found, and the lowest densities are those obtained from L composites (123 kg/m3). Moreover, the aerogel density and shrinkage have been significantly reduced through the employment of the polyurethane (PU) foam skeleton. Due to the enhanced mechanical properties of polyurethane aerogels, the inclusion of polyurethane aerogel into the foam skeleton helps to increase the elastic modulus of the foams from 0.03 and 0.08 MPa to 0.85 MPa, while keeping great flexibility and recovery ratios. Moreover, the synthesized PUF–PUA composites show an excellent insulating performance, reducing the initial thermal conductivity values from 34.1, 40.3, and 50.6 mW/(m K) at 10 °C for the foams S, M, and L, to 15.8, 16.6, and 16.1 mW/(m K), respectively. Additionally, the effect of the different heat transfer mechanisms to the total thermal conductivity is herein analyzed by using a theoretical model as well as the influence of the measurement temperature.
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Chatzi, P., A. Antoniadou, T. Efstathiadis i A. I. Kalfas. "Thermal performance investigation of metal foam heat exchanger for micro-gas turbine". Journal of Physics: Conference Series 2511, nr 1 (1.05.2023): 012013. http://dx.doi.org/10.1088/1742-6596/2511/1/012013.
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Abstract This study presents the experimental monitoring of heat transfer performance of metal foams in transient state. Micro gas turbines require a compact recuperator with high effectiveness to achieve higher thermal efficiency. Porous media such as metal and ceramic foams are characterised by high surface-to-volume ratio. They are known to increase heat transfer and potentially can be incorporated in recuperators. Their structure is ideal for thermal management of compact and lightweight applications. The idea is to combine excellent thermal properties of metal foams with turbine gases heat fluxes exploitation, in order to elevate the temperature of a different working fluid such as water or compressed air before it enters the combustor. A novel facility was designed and developed for monitoring heat transfer mechanisms that occur in metal foams. A copper cylinder is filled with metal foam which is heated in transient state by a sudden switch from cold to hot water flow whereas a cold stream cools the device in a crossflow configuration. The study demonstrates a method based on computerisation of true-colour analysis of digital images for surface temperature visualisation using thermochromic liquid crystals (TLC). Results of temperature as well as local and mean heat transfer coefficient were obtained showing that the hot flow inside the foam was more dominant in heat transfer than the cold flow in the empty channel. The method is promising for the evaluation of transient phenomena in a tube that is filled with porous media.
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Muth, Joseph T., Patrick G. Dixon, Logan Woish, Lorna J. Gibson i Jennifer A. Lewis. "Architected cellular ceramics with tailored stiffness via direct foam writing". Proceedings of the National Academy of Sciences 114, nr 8 (8.02.2017): 1832–37. http://dx.doi.org/10.1073/pnas.1616769114.
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Hierarchical cellular structures are ubiquitous in nature because of their low-density, high-specific properties, and multifunctionality. Inspired by these systems, we created lightweight ceramic architectures composed of closed-cell porous struts patterned in the form of hexagonal and triangular honeycombs by direct foam writing. The foam ink contains bubbles stabilized by attractive colloidal particles suspended in an aqueous solution. The printed and sintered ceramic foam honeycombs possess low relative density (∼6%). By tailoring their microstructure and geometry, we created honeycombs with different modes of deformation, exceptional specific stiffness, and stiffness values that span over an order of magnitude. This capability represents an important step toward the scalable fabrication of hierarchical porous materials for applications, including lightweight structures, thermal insulation, tissue scaffolds, catalyst supports, and electrodes.
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Bora, Neetu, i Deepika P. Joshi. "Enhancement in Thermal Properties of Organic Phase Change Material (Paraffin) via TiO2 Foam Doping". Prabha Materials Science Letters 2, nr 1 (1.03.2023): 1–15. http://dx.doi.org/10.33889/pmsl.2023.2.1.001.
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Phase change materials (PCM) can absorb or release a huge amount of latent heat in accordance with the increase or decrease of the surrounding temperature. Among all the studied PCMs, organic PCM paraffin has been chosen due to the large energy storage capacity for thermal energy storage (TES). The present work introduces a thermally modified phase change material by TiO2 foam impregnation in paraffin. Three TiO2/paraffin PCM composites TPCM1, TPCM2, and TPCM3 containing 10 wt.%, 15 wt.%, and 20 wt.% of TiO2 foam with paraffin have been successfully synthesized for thermal energy storage. The porous TiO2 foam can provide a high paraffin loading capacity of up to 80 % (TPCM3) due to hollow cavities. TiO2 foam is uniformly distributed over the inner and outer surface of the paraffin as a nano additive to enhance the thermal conductivity (TC) of the composite PCM. The structural, morphological, and thermal study revealed that doping of the supporting material has potentially modified all the criteria of PCM composite for TES. The highest leakage-proof result was obtained for 20 wt.% of TiO2 foam impregnated composite (TPCM3) by analysing mass loss across 500 thermal cycles in an oven at 80°C. The thermal reliability of the TPCM3 composite has also been investigated after 500 thermal cycles. The TPCM3 composite maintains its crystalline nature with homogeneous dispersion and thermal stability without affecting the thermal and chemical properties of the PCM. The latent heat of the TPCM3 composite reached 182.87 J/g, and the thermal conductivity has been calculated at 0.71 W/m-K, which is 3.73 times higher than paraffin. The results concluded that synthesized TPCM3 composite could be a potential candidate for TES due to chemical and physical compatibility, easy synthesis process, good thermal and chemical reliability, and acceptable energy storage capacity with enhanced thermal conductivity.
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Pan, Changyu, Ping He i Enqi Shi. "Numerical simulation of thermal properties of cubic period metal foam embedded graphene-aerogel composite PCM". Journal of Physics: Conference Series 2383, nr 1 (1.12.2022): 012128. http://dx.doi.org/10.1088/1742-6596/2383/1/012128.
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In the context of green and clean energy, latent heat energy storage by phase change materials is considered as one of the important energy technologies. In this paper, a new metal foam embedded graphene aerogel composite phase change material is developed, and pore-scale numerical simulations are performed in order to investigate the thermal properties of this composite phase change material. Among them, this paper designs copper foam with cubic periodic unit structure, which not only has high thermal conductivity, high porous structure and low relative density, but also can be rapidly fabricated by new fabrication techniques, while paraffin and erythritol are selected as PCM embedded in the metal foam. By analyzing the temperature-time and liquid phase-time relationship graphs, it is known that the new composite phase change material has more uniform internal temperature distribution and shorter melt condensation time compared to graphene-aerogel composite PCM, which provides a method for thermal management of PCMs.
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Chen, Ming Yung, i Cheng Gang Chen. "Lightweight Hybrid Foam with Dimensional Stability". Advances in Science and Technology 63 (październik 2010): 114–19. http://dx.doi.org/10.4028/www.scientific.net/ast.63.114.
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Availability of advanced materials has opened up opportunities in meeting several functional requirements through hybridization. Hybrids consisting of ceramics, metals and high performance polymers could benefit many aircraft and space satellite applications. They could meet requirements of low weight, high environmental stability, and high thermal or dimensional stability. In this study, hybrid materials consisting of high performance polymer, porous ceramics (glass microballoons) and other constituents such as Zircornium Tungstate (with negative coefficient of thermal expansion (CTE)) and nanoclay were studied. Specimens were successfully produced with a range of density from 0.4 to 1.1 g/cm3 depending on the degree of fill in the syntactic foams. CTE tailoring was achieved to greatly reduce the residual stress arising from processing and CTE mismatch of dissimilar materials. The evaluations of dimensional stability were examined from thermomechanical analysis. The synergistic effects of resin, ceramic constituents and pores on the hybrid properties will be presented.
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Xu, Siqi, Zhiyong Wu, Hongyan Lu i Lixin Yang. "Experimental Study of the Convective Heat Transfer and Local Thermal Equilibrium in Ceramic Foam". Processes 8, nr 11 (18.11.2020): 1490. http://dx.doi.org/10.3390/pr8111490.
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Foam materials have been widely used in various industrial applications, where higher and higher heat and mass transfer performances are pursued. However, the mechanism of many factors on the heat transfer performances is still unclear. The main purpose of this article is to investigate how the porous properties, porosity, cell size and the sample thickness affect the volumetric convective heat transfer. In this study, the single-blow method is used to determine the volumetric heat transfer coefficient of ceramics foam in the temperature range from 283 K to 323 K. In particular, sensitivity analysis of the foam porosity, cell size, velocity and the sample thickness on the volumetric heat transfer coefficient within the ceramics foam were all conducted. The results indicate that the sample thickness has a significant effect on the volumetric heat transfer coefficient which decreases with the sample thickness. In addition, the local thermal equilibrium phenomenon is verified and its influence on the volumetric heat transfer coefficient discussed. Based on the experimental data, a new correlation is proposed that includes sample thickness, porosity, superficial velocity and fluid properties. This study is crucial to the theory of the convective heat transfer inside the porous media, and can be used to guide the design and optimization of volumetric solar air receivers, compact heat exchangers, heat sinks, heat regenerators, packed bed reactors and so on.
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Zhao, C. Y., T. J. Lu i H. P. Hodson. "Measurements of thermal radiation in ultralight metal foams with open cells". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 218, nr 11 (1.11.2004): 1297–307. http://dx.doi.org/10.1177/095440620421801102.
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Highly porous ultralightweight cellular metal foams with open cells have attractive mechanical, thermal, acoustic and other properties and are currently being exploited for hightemperature applications (e.g. acoustic liners for combustion chambers). In such circumstances, thermal radiation in the metal foam becomes a significant mechanism of heat transfer. This paper presents results from experimental measurements on radiative transfer in Fe-Cr-Al-Y (a steel-based high-temperature alloy) foams having high porosity (95 per cent) and different cell sizes, manufactured at low cost from the sintering route. The spectral transmittance and reflectance are measured at different infrared wavelengths ranging from 2.5 to 50 μ, which are subsequently used to determine the extinction coefficient and foam emissivity. The results show that the spectral quantities are strongly dependent on the wavelength, particularly in the short-wavelength regime (less than 25 μ). While the extinction coefficient decreases with increasing cell size, the effect of cell size on foam reflectance is not significant. When the temperature is increased, the total extinction coefficient increases but the total reflectance decreases. The effective radiative conductivity of the metal foam is obtained by using the guarded hot-plate apparatus. With the porosity fixed, the effective radiative conductivity increases with increasing cell size and increasing temperature.
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Gopinathan, A., J. Jerz, J. Kováčik, T. Dvorák i L. Orovčík. "Study of internal porous structure formation of the powder metallurgically prepared aluminium foam". Journal of Physics: Conference Series 2045, nr 1 (1.10.2021): 012003. http://dx.doi.org/10.1088/1742-6596/2045/1/012003.
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Abstract The internal pore wall structure formation and density play an important role in improving the mechanical and thermal properties of the closed-cell aluminium foams. The present research work aims to investigate the internal structure formation of the aluminium foam prepared by powder metallurgy and the uniformity of the distribution of the pores when the minimum amount of TiH2 is added. The foamable precursor of two different aluminium alloys (Al-1050 and A5083) is produced with a TiH2 gaseous agent of 0.05 wt.%. The parameters analysed include the density, pore wall formations, pore, and metal density distribution inside the structure with the help of X-ray tomography. Furthermore, the image-processing technique has been adopted to produce the 3D surrogate model of the foam for visual inspection and analysis. The obtained results show the importance of the amount of TiH2 addition and of the foaming furnace temperature in deciding the internal porous structure formation. Further, the pore morphology of lower porosity foams (in the range of 30-40 % porosity) of the two alloys produced at 690 °C furnace temperature is investigated with the help of developed surrogate models. The presence of micropores and uniformity of the distribution of pores found brings the idea of choosing the optimized structure of foam for thermal energy storage systems associated with PCM.
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Mácová, Petra, Konstantinos Sotiriadis, Zuzana Slížková, Petr Šašek, Michal Řehoř i Jaroslav Závada. "Evaluation of Physical Properties of a Metakaolin-Based Alkali-Activated Binder Containing Waste Foam Glass". Materials 13, nr 23 (30.11.2020): 5458. http://dx.doi.org/10.3390/ma13235458.
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Foam glass production process redounds to large quantities of waste that, if not recycled, are stockpiled in the environment. In this work, increasing amounts of waste foam glass were used to produce metakaolin-based alkali-activated composites. Phase composition and morphology were investigated by means of X-ray powder diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy. Subsequently, the physical properties of the materials (density, porosity, thermal conductivity and mechanical strength) were determined. The analysis showed that waste foam glass functioned as an aggregate, introducing irregular voids in the matrix. The obtained composites were largely porous (>45%), with a thermal conductivity coefficient similar to that of timber (<0.2 W/m∙K). Optimum compressive strength was achieved for 10% incorporation of the waste by weight in the binder. The resulting mechanical properties suggest the suitability of the produced materials for use in thermal insulating applications where high load-bearing capacities are not required. Mechanical or chemical treatment of the waste is recommended for further exploitation of its potential in participating in the alkali activation process.
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Kamińska, Klaudia, Mateusz Barczewski, Maria Kurańska, Elżbieta Malewska, Krzysztof Polaczek i Aleksander Prociak. "The Effect of a Chemical Foaming Agent and the Isocyanate Index on the Properties of Open-Cell Polyurethane Foams". Materials 15, nr 17 (2.09.2022): 6087. http://dx.doi.org/10.3390/ma15176087.
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This article presents an ecological approach based on climate neutrality to the synthesis of open-cell polyurethane foams with modified used cooking rapeseed oils. Water was used as a chemical blowing agent in the amount of 20–28 wt.% in relation to the weight of the bio-polyol. The influence of water on the physical and mechanical properties of the synthesized foams was investigated. The resultant porous materials were tested for the content of closed cells, cell structure, apparent density, thermal conductivity, compressive strength, and dimensional stability. It was found that the apparent density decreased in the range of 11–13 kg/m3 when the amount of the foaming agent was increased. In the next step, a foam with a water content of 22% was selected as having the most favorable physico–mechanical properties among all the foams with various water contents. The isocyanate index of the selected foam was then changed from 0.6 to 1.1 and it was observed that the compressive strength increased by an average of 10 kPa. The thermal conductivity coefficients of the final materials with different water contents and isocyanate indices were comparable and in the range of 40–43 mW/m·K.
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Zach, Jiri, Rudolf Hela, Jitka Peterková i Martin Sedlmajer. "Utilization of Lightweight Aggregate from Expanded Obsidian for Advanced Thermal Insulating Plasters Production". Advanced Materials Research 335-336 (wrzesień 2011): 1199–203. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.1199.
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The thermal insulating of new and existing buildings is of a key influence in reduction of their energetic demand factor resulting in reduction of emissions of gases, carbon particles and dust which directly improves the environment. At development of light thermal insulation plasters with very low thermal conductivity the foam-plastic matters or light porous aggregates are frequently used at present. The foam-plastic materials do not appear as convenient ones in view of the environment and sustainable development as well. In the given case the thermal insulation plasters based on light cellular aggregates appear as more suitable. However a majority of light aggregates (for example expanded perlite) do not show a good ratio of insulation and mechanical properties. The paper describes a design and development of thermal insulation plasters based on expanded obsidian that can be used for thermal insulating of building constructions and for moisture sanitation. Considering the applied type of aggregates the materials show better ratio of thermal insulation and mechanical properties while in practice the plasters can be used as a full- value alternative for classical thermal insulation systems.
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Baillis, Dominique Doermann, Remi Coquard, Jaona Randrianalisoa, Leonid A. Dombrovsky i Raymond Viskanta. "THERMAL RADIATION PROPERTIES OF HIGHLY POROUS CELLULAR FOAMS". Special Topics & Reviews in Porous Media - An International Journal 4, nr 2 (2013): 111–36. http://dx.doi.org/10.1615/specialtopicsrevporousmedia.v4.i2.20.
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Chi, Hiep Le, Pavlína Hájková, Su Le Van, Petr Louda i Lukáš Voleský. "Water Absorption Properties of Geopolymer Foam after Being Impregnated with Hydrophobic Agents". Materials 12, nr 24 (11.12.2019): 4162. http://dx.doi.org/10.3390/ma12244162.
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Geopolymer foam is classified as a lightweight material with high porous in its matrix which has great offer for applications requiring fire-resistant, thermal, and acoustic properties. However, the high sensitivity to humid environments can be a major barrier of geopolymer foam that limits the variety of applications of this material. Based on this drawback, two types of hydrophobic agent (Lukosil M130 and Lukofob ELX) were used as an impregnator to treat the surface of geopolymer foam samples. This paper presented the results of water absorption properties of the untreated and treated geopolymer foam composites. The obtained properties were flexural strength, compressive strength, density, total water absorption, the rate of water absorption, and water absorption coefficient. The results showed that the samples after being impregnated with hydrophobic agents improved significantly their waterproof property especially using Lukosil M130. Moreover, the samples treated with Lukosil M130 had positive impact on their mechanical strength.
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Jia, Cai Yun, Rui Ding, Jun Cheng Liu, An Fa Liu i Dong Xiao Teng. "Effects of Al(OH)3 on the Structure and Properties of Foam Ceramics Cemented by Phosphate". Advanced Materials Research 1120-1121 (lipiec 2015): 21–26. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.21.
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High alumina foam ceramics products with low density, high specific surface area, low thermal conductivity, corrosion resistance and other excellent physical and chemical properties are suitable for chemical, metallurgy and other related fields [1-4]. Alumina foam ceramics that compression strength increased by 200%, was prepared by Rizwan Ahmad through impregnation process using foamed rubber [5]. However foamed rubber was expensive and could be decomposed creating poisonous gases at high temperature. Zhou l z [6] prepared mullite porous ceramics with high strength by gel-casting method. Gel-casting is an effective method for preparation of ceramics products with large size and complicated shape. Fiber reinforced dense ceramics composite materials with excellent performance have been studied widely [7-10], it is also an important issue to adequately investigate the reinforcement of porous ceramics with fiber.
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Miryuk, Olga, Roman Fediuk i Mugahed Amran. "Foam Glass Crystalline Granular Material from a Polymineral Raw Mix". Crystals 11, nr 12 (24.11.2021): 1447. http://dx.doi.org/10.3390/cryst11121447.
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The article is devoted to the development of resource-saving technology of porous granular materials for energy-efficient construction. The relevance of the work for international research is to emphasize expanding the raw material base of porous lightweight concrete aggregates at the expense of technogenic and substandard materials. The work aims to study the processes of porization of glass crystalline granules from polymineral raw materials mixtures. The novelty of the work lies in the establishment of regularities of thermal foaming of glass crystalline granules when using waste of magnetic separation of skarn-magnetite (WMS) ores and lignite clay. Studies of liquid glass mixtures with various mineral fillers revealed the possibility of the formation of a porous structure with the participation of opoka, WMS and lignite clay. This is due to the presence in the materials of substances that exhibit thermal activity with the release of a gas phase. The foaming efficiency of the investigated materials increases when combined with glass breakage. The addition of WMS and lignite clay to the glass mixture increases the pore size in comparison with foam glass. The influence of the composition of raw mixtures on the molding and stability of granules is determined. The addition of sodium carbonate helps to strengthen the raw granules and reduce the softening temperature of the mass. The composition of the molding mixture of glass breakage, liquid glass and a multicomponent additive is developed, which provides an improvement in the molding properties of the glass mass, foaming of granules at a temperature of 750 °C. Foam glass crystalline granules have polymodal porosity, characterized by a density of 330–350 kg/m3, a compressive strength of 3.2–3.7 MPa, and a thermal conductivity of 0.057–0.061 W/(m·°C). Accordingly, the developed granules have a high potential use in structural and heat-insulating concretes.
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Negahdari, Zahra, M. Solati i A. Saberi. "Influence of Slurry Formulation on Mechanical Properties of Reticulated Porous Ceramic". Advances in Science and Technology 45 (październik 2006): 2061–66. http://dx.doi.org/10.4028/www.scientific.net/ast.45.2061.
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Increased processing pressure has resulted in need for the industry to optimize mechanical properties of ceramic foam filters used for molten metal processing. This paper will summarize the effect of ceramic slurry formulation on mechanical properties of reticulated porous ceramics processed by replica method. Commercial polyurethane sponge materials were chosen as a template to produce the RPC (reticulated porous ceramic) from a shear thinning multi component aqueous slurry composed of alumina, SiC, colloidal silica and some different additives. Thermal transformation sequence of the mixtures, resultant macrostructure and microstructure, relative density, grain morphology, phase composition, and mechanical strength of the sintered porous ceramics were investigated. Mechanical properties of struts were investigated by a theoretical model. The RPC had its maximum strength when Alumina/SiC weight ratio was 4.4. Such materials sintered at 1650° C in air, due to their excellent functional properties, are suitable for application as molten metal filter.
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Arreola-Ramos, Carlos E., Omar Álvarez-Brito, Juan Daniel Macías, Aldo Javier Guadarrama-Mendoza, Manuel A. Ramírez-Cabrera, Armando Rojas-Morin, Patricio J. Valadés-Pelayo, Heidi Isabel Villafán-Vidales i Camilo A. Arancibia-Bulnes. "Experimental Evaluation and Modeling of Air Heating in a Ceramic Foam Volumetric Absorber by Effective Parameters". Energies 14, nr 9 (27.04.2021): 2506. http://dx.doi.org/10.3390/en14092506.
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Reticulate porous ceramic reactors use foam-type absorbers in their operation which must fulfill two essential functions: favoring the volumetric effect and increasing the mass and heat transfer by acting as a support for the reactive materials. Heating these absorbers with highly inhomogeneous concentrate irradiation induces high thermal gradients that affect their thermal performance. Owing to the critical function of these component in the reactor, it is necessary to define a selection criterion for the foam-type absorbers. In this work, we performed an experimental and numerical thermal analysis of three partially stabilized zirconia (PSZ) foam-type absorbers with pore density of 10, 20, and 30 PPI (pores per inch) used as a volumetric absorber. A numerical model and an analytical approximation were developed to reproduce experimental results, and calculate the thermal conductivity, as well as volumetric heat transfer coefficient. The results show that an increase in pore density leads to an increase in the temperature difference between the irradiated face and the rear face of the absorber, this occurs because when pore density increases the concentrated energy no longer penetrates in the deepest space of the absorber and energy is absorbed in areas close to the surface; therefore, temperature gradients are created within the porous medium. The opposite effect occurs when the airflow rate increases; the temperature gradient between the irradiated face and the rear face is reduced. This behavior is more noticeable at low pore densities, but at high pore densities, the effect is less relevant because the internal structure of porous absorbers with high pore density is more complex, which offers obstructions or physical barriers to airflow and thermal barriers to heat transfer. When the steady state is reached, the temperature difference between the two faces of the absorber remains constant if the concentrate irradiation changes slightly, even changing the airflow rate. The results obtained in this work allow us to establish a selection criterion for porous absorbers that operate within solar reactors; this criterion is based on knowledge of the physical properties of the porous absorber, the environment, the working conditions, and the results expected.
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Bao, Huai Qian, Ning Zhang i Xue Gang Hou. "Analysis of the Influence of Static Flow Resistance on the Sound Absorption Properties of Aluminum Foam". Advanced Materials Research 535-537 (czerwiec 2012): 1459–62. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.1459.
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For the complexity of the internal microstructure of porous aluminum foam, on the basis of Rayleigh-Kirchhoff circular tube model, taking viscosity loss and thermal transmission, the paper establishes a simplified theoretical model for sound absorption properties of aluminum foam. The paper also calculates and analyzes the influence of Static flow resistance on the sound absorption properties in the rigidity and cavity backing. The results show that the peak frequency moves to lower with the increasing of the thickness of the air layer. What’s more, there is a direct corresponding relation between flow resistance and the best sound absorption frequency range of aluminum foam. In a reasonable range of flow resistance value, the capability of sound absorption reach optimal, Aluminum Foam won’t have fine sound absorption capability if the value of flow resistance is too big or small.
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Kroupová, I., V. Bednářová, T. Elbel i F. Radkovský. "Proposal of Method of Removal of Mould Material from the Fine Structure of Metallic Foams used as Filters". Archives of Metallurgy and Materials 59, nr 2 (1.06.2014): 727–30. http://dx.doi.org/10.2478/amm-2014-0120.
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Abstract Metallic foams are materials that are subject of an ongoing research with the broad applicability in many different areas (e.g. automotive industry, building industry, medicine, etc.). These metal materials contain in their structure artificially created pores. These pores give them specific properties, such as: large rigidity at low density, high thermal conductivity, capability to absorb energy, etc. Since the discovery of porous metallic materials numerous methods of production have been developed. The aim of the paper is to introduce effective casting methods of manufacturing of metallic foams, namely cast metal filters from the aluminum alloy. Research deals with investment casting with use of pattern made of polymeric foam, which is used for production of metallic foam with open pores. The main disadvantage of this procedure consists in removing the mould material without damaging the fine structure of the cast filter. Plaster is used as the mould material and the most important result of this paper is the presentation of the effective procedure of plaster removal from the porous structure of cast filters.
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Adamek, Grzegorz, Adam Junka, Przemyslaw Wirstlein, Mieczyslawa U. Jurczyk, Piotr Siwak, Jeremiasz Koper i Jaroslaw Jakubowicz. "Biomedical Ti-Nb-Zr Foams Prepared by Means of Thermal Dealloying Process and Electrochemical Modification". Materials 15, nr 6 (14.03.2022): 2130. http://dx.doi.org/10.3390/ma15062130.
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The paper presents results of preparation and modification of Ti20Nb5Zr foams by a thermal dealloying method followed by electrochemical modification. The first step of this study was the preparation of Ti20Nb5Zr30Mg nanopowder using mechanical alloying (MA). The second was forming green compacts by cold pressing and then sintering with magnesium dealloyed from the structure, which resulted in pores formation. The next step was surface modification by electrochemical etching and silver nanoparticle deposition. Porosity, morphology, mechanical properties as well as biocompatibility and antibacterial behavior were investigated. Titanium foam porosity up to approximately 60% and wide pore size distribution were successfully prepared. The new materials have shown positive behavior in the MTT assay as well as antibacterial properties. These results confirmed great potential for thermal dealloying in preparation of porous structures.
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EKİZ BARIŞ, Kübra, i Leyla TANAÇAN. "Natural pozzolan-based green geopolymer foam for thermal insulation". Journal of Sustainable Construction Materials and Technologies 7, nr 3 (30.09.2022): 128–44. http://dx.doi.org/10.47481/jscmt.1142100.
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The purpose of the current study is to investigate the possibility of volcanic Tuff of Earth of Datça (ED) in Turkey to be used as an aluminosilicate source in the production of a geopolymer foam for thermal insulation. An extensive evaluation of the effects of fine sand-to-pozzolan and Al powder-to-pozzolan ratios on the physical, mechanical, and thermal properties and morphology (porosity, average and maximum pore diameter, pore size distribution) of the pores were carried out. The sodium silicate and potassium hydroxide (12.5 M) solutions with an activator ratio of 2.5 were used as alkali activators and Al powder was used as a foaming agent. Research results reveal that Earth of Datça is a suitable precursor for the production of a geopolymer foam. Fine sand and aluminum powder contents are key factors on optimum foam structure. Addition of finely ground silica sand ensured the volumetric stability of the binder and prevented the collapse after swelling of the binder. The optimum Al powder-to-pozzolan ratio was determined as 0.5 % because it gives higher physical, mechanical and thermal properties due to the more homogenous microstructure with finer pore size, narrower pore size distribution and lower degree of interconnectivity between the pores. Research results also show that natural volcanic Tuff of Datça Peninsula as aluminosilicate source gives promising results in the field of producing highly porous geopolymers with low thermal conductivity (0.087-0.134 W/mK), high porosity (72.3-82.6 %) and an acceptable compressive strength (0.40-2.09 MPa). This study contributes to the literature that Earth of Datça-based geopolymer foam may function well as an insulation material for building enclosure.