Electrothermal Characteristics of Cement Based Conductive Composites
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Based on the experimental results, the electrothermal characteristics of graphite cement and carbon fiber graphite cement conductive composites were studied. Cement based conductive materials developed in this paper exhibit good resistance to over current and over voltage, lower surface temperature and excellent stability during heating. They are especially suitable for using as electrothermal materials.Cite
Traditional insulation material is thermally insulating and has a low thermal conductivity. The miniaturisation and higher power of electrical devices would generate lots of heat, which have created new challenges to safe and stable operation of the grid. The development of insulating materials with high thermal conductivity provides a new method to solve these problems. The improvement of thermal conductivity would increase the ability to conduct heat and greatly reduce the operating temperature of the electrical equipment, which could reduce the equipment size and extend service life. On the other hand, inorganic thermally conductive particles and the improved thermal conductivity may have great effect on thermal breakdown. In this study, the factors affecting the thermal conductivity of dielectric polymer composites were explored. Intrinsic thermal conductive polymer and particle-filled thermal conductive composites were discussed. Effect of thermal conductivity, shape, size, surface treatment of the particle and prepare process on thermal properties of the composites were illustrated. This study focused on the electrical and thermal properties of thermally conductive epoxy, polyimide and polyethylene composites. Tracking failure caused by thermal accumulation is a typical thermal breakdown phenomenon. The performance of the resistance to tracking failure was studied for these composites. The results showed that thermal conductive particles improved the resistance to tracking failure. Finally, application of thermally conductive epoxy in electrical equipment was discussed.
Thermal bridge
Thermal grease
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This research article presents the mechanical and thermal properties of cement-based composite for thermal energy storage materials enriched with containing nanoTiO 2 particle size (25 nm) and concentration (1-5 wt.%) were systematically investigated. Thermal properties coefficients were tested using a direct measuring instrument with surface probe (ISOMET2114). The influence of nanoTiO 2 on the performance, such as compressive strength, bulk density, thermal conductivity, volume heat capacity and thermal diffusivity of hardened composite cement pastes were studied for future solar thermal energy materials with better performance. According to the development of thermal storage materials and their application environment requirement in solar thermal power, the specimens were subjected to heat at 350°C and 900°C. It was observed that, before heating, the compressive strength is optimized at nanoTiO 2 amount of 2 wt%. Moreover, after heating at 350 °C and 900°C, the thermal conductivity and volume heat capacity of the cement paste enriched with nanoTiO 2 were significantly lesser than that of the before heating one.
Thermal effusivity
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Minimum-mass designs were obtained for insulated structural panels loaded by a general set of inplane forces and a time dependent temperature. Temperature and stress histories in the structure are given by closed-form solutions, and optimization of the insulation and structural thicknesses is performed by nonlinear mathematical programming techniques. Design calculations are described to evaluate the structural efficiency of eight materials under combined heating and mechanical loads: graphite/polyimide, graphite/epoxy, boron/aluminum, titanium, aluminum, Rene 41, carbon/carbon, and Lockalloy. The effect on design mass of intensity and duration of heating were assessed. Results indicate that an optimum structure may have a temperature response well below the recommended allowable temperature for the material.
Transient (computer programming)
Carbon fibers
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High thermal conductive epoxy composites are particularly suitable for impregnation process of superconducting power equipments due to their high electrical insulation property and low thermal expansion. This work optimized the preparation and impregnation procedures of high thermal conductive epoxy composites. Based on the orthogonal experiment results and the range analysis, the critical factors effecting on the thermal conductivity of final product in sequence were determined. Through investigating the preparation factors of thermal conductive AlN/EP composites on their electrical insulation properties further, it was found that the increase of filler content, addition of nano fillers and low curing temperature are advantageous for improving the electrical insulation property of composites.
Filler (materials)
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Gauge factor
Resistive touchscreen
Strain gauge
Linearity
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Abstract Thermal insulation materials with high strength and ultra-low thermal conductivity are ideal construction ones for residential infrastructure. However, high strength of materials regularly means high thermal conductivity. To solve this problem, a novel thermal insulation material was prepared by using cement as the binder, silica fume as the mineral admixture, aerogel as the coarse filler and hollow SiO 2 microsphere as the fine filler. The optimal proportion and preparation process were investigated by means of the orthogonal experiment and the single factor experiment method, respectively. On the other hand, their microstructures, in terms of aerogel particle size distribution and multi-scale composite structure were analysed by optical microscope, binarization image, scanning electron microscope. The results indicated that compared to conventional insulation materials, the produced materials in this study behaved much better performance in strength. The dry density, compressive strength and thermal conductivity reached 360 kg/m 3 , 4.55 MPa and 0.055 W/m·K, respectively. The incorporation of hollow SiO 2 microsphere and silica fume led to the much thicker pore walls of the sample, and simultaneously the prolonging of stirring time resulted in the much smaller size of aerogel, which were considered as the two primary causes of its excellent mechanical performance.
Silica fume
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Abstract. The carbon fiber-slag conductive concrete is prepared in carbon fiber and slag elementary material of function. Under the conditions of a certain amount of Carbon fiber, research has been carried out in different slag content. The electric mechanical effects of Imposing loads has been carried out. The results indicated that: slag can improve compression capacity. And the compression capacity can be reduced by adding some steel slag while adding some amount. Carbon fibre-slag concrete can be used as self-monitoring materials fracture by the electric mechanical effects
Slag (welding)
Carbon fibers
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Silica fume
Matrix (chemical analysis)
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This research aims in characterizing modified cement mortar with carbon nanotubes (CNTs) that act as nanoreinforcements leading to the development of innovative materials possessing multi-functionality and smartness. Such multifunctional properties include enhanced mechanical behavior, electrical and thermal conductivity, and piezo-electric characteristics. The effective thermal properties of the modified nano-composites were evaluated using IR Thermography. The electrical resistivity was measured with a contact test method using a custom made apparatus and applying a known D.C. voltage. To eliminate any polarization effects the specimens were dried in an oven before testing. In this work, the thermal and electrical properties of the nano-modified materials were studied by nondestructively monitoring their structural integrity in real time using the intrinsic multi-functional properties of the material as damage sensors.
Thermography
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