Search

The incorporation of carbon materials can effectively enhance the performance of thermoelectric materials. By optimizing the thermoelectric properties of the carbon scaffold, it is possible to further improve the thermoelectric performance of the prepared carbon-based composites. To elevate the thermoelectric performance of the carbon scaffold, this work introduces a novel mesoscopic design strategy, utilizing natural flake graphite to create a three-dimensional ordered porous framework. Highly controllable anisotropic conductivity and thermal conductivity of the porous graphite skeleton were achieved, by combining sizable sodium chlorine templates (37.5–250 μm) with a natural flake graphite matrix (50–150 μm). A porous graphite with high electrical conductivity and low thermal conductivity along the vertical axis was obtained by carefully regulating the parameters. The sample demonstrated exceptional thermoelectric conversion performance, achieving a thermoelectric power factor of 12.2 μW m−1 K−2 and a figure of merit value of 28.3 × 10−4. Furthermore, the thermoelectric property of the samples could be greatly improved by adding a small amount of ferric chloride, with a thermoelectric power factor reaching 41.9 × 10−4 and a thermoelectric figure of merit reaching 81.4 μW m−1 K−2. This work provides an effective scheme for the mesoscopic regulation of porous graphite carbon structures and offers a new strategy for enhancing the performance of thermoelectric generators. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphite foams were prepared using foaming method and template method with nature flake graphite powder as main raw materials, sucrose as a foaming agent or binder, as well sodium chloride as a template. The compositions, microstructure, thermal properties and mechanical performance of the fabricated graphite foams were investigated by X-ray fluorescence spectrometer, scanning electron microscope, laser thermal conductivity meter, and electronic universal testing machine, respectively. The results show that water in binder played an important role in forming process of graphite foams. Graphite foams with controllable pore structure can be obtained by template method. The porosity of graphite foams increased with increasing the concentration of templating agent. With a fixed concentration of the templating agent the thermal diffusivity of the foams deceased with increasing the concentration of binder. Moreover, the obtained graphite foams has a minimum density of 288 kg/m3, a maximum porosity of 78% and a maximum thermal diffusivity of 7.14 × 10−6 m2/s. Two binding models of graphite foams prepared using template method has been proposed in the first time. This work provided an optimized processing for graphite foams with simple preparation, low-cost recyclable raw materials, and a promising thermal management material for many applications. Image 1 • New type of graphite foams were developed using natural flake graphite as main raw material. • Two binding models of graphite foams prepared using template method has been proposed. • Water can promote the pore-forming during the forming process of graphite foams. • The routes have superiority of simple, low-cost with recyclable raw materials. [ABSTRACT FROM AUTHOR]

Abstract: Aluminosilicate-reinforced carbon foams have been prepared by chemical foaming with phenolic resin as matrix precursor and aluminosilicate as the additive. The effects of the amount of aluminosilicate used on the microstructure, mechanical properties and oxidation resistance of the carbon foams have been investigated by scanning electronic microscopy, mechanical testing, and oxidation weight loss, respectively. The results show that the amount of aluminosilicate added has a significant influence on the surface roughness and the structure uniformity of carbon foams. The compressive strengths are usually higher than that of the pure carbon foam sample by as much as 60%. The percentage of weight loss of the carbon foams drops with increasing aluminosilicate content up to 11wt%, but then increases. [Copyright &y& Elsevier]

Abstract: Large-size carbon/carbon composites (Φ 450× Φ 230×15mm3) have been produced by chemical vapor infiltration with kerosene as precursor. The microstructure of pyrocarbon was examined by polarized light microscopy and scanning electron microscopy. The infiltration kinetics was analyzed to investigate the infiltration rate limitation by parameters such as temperature. The results show that rough laminar carbon constitutes the majority of the matrix at a medium temperature (about 1100°C), while smooth laminar and isotropic structures occur at temperatures lower than 1000°C and higher than about 1200°C, respectively. The apparent activation energy of kerosene decomposition in the temperature range 900–1200°C is about 125.6kJ/mol. [Copyright &y& Elsevier]

To overcome the poor shape stability, low thermal conductivity, and weak photo response of phase change materials (PCMs), we designed a kind of Gelatin@nanoGraphite aerogel with aligned channel structure of graphite nanosheets and a new type of stable Paraffin/Gelatin@nanoGraphite composite PCMs was fabricated in this work. The graphite nanosheets were used as thermal conduction and photon absorption fillers. The microstructure, thermal conductivity, thermal stability, and solar-thermal conversion of the composite PCMs have been investigated. The results show that the rich porosity of the prepared Gelatin@nanoGraphite aerogel effectively loads a large amount of paraffin wax (>93.2 wt%). Meanwhile, the composite PCMs had anisotropic solar-thermal conversion and thermal conductivity (radial 3.75 and axial 2.59 W/(m·K)), high melting enthalpy (>146.4 J/g), and excellent phase change cycle and shape stability. This material has intensive application prospects in the fields of building energy saving, human body hyperthermia and solar energy collection system. Paraffin/Gelatin@nanoGraphite PCMs with anisotropic thermal conduction capacity and solar-thermal conversion ability were prepared by directional freeze-drying process and vacuum impregnation. [Display omitted] [ABSTRACT FROM AUTHOR]