In this paper, the effect of imperfect inner interface on the stress fields in the coated inclusion composite is investigated, the spring-layer of vanishing thickness model is introduced to simulate the imperfect inte...
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In this paper, the effect of imperfect inner interface on the stress fields in the coated inclusion composite is investigated, the spring-layer of vanishing thickness model is introduced to simulate the imperfect interface, assuming that across the interface between the inclusion and the coating the interfacial traction is continuous while displacement discontinuities are permitted through interfacial traction-displacement jump relations. Numerical examples corresponding to the composites containing single coated spherical and fibrous inclusion, respectively, under shear loading at infinity, are calculated, which indicate that the imperfect inner interfaces have significant effect on stress fields of the composites.
SiCp/Al composites containing high volume fraction of SiC particles were fabricated by spark plasma sintering (SPS), and their thermophysical properties, such as thermal conductivity (TC) and coefficient of thermal ex...
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ISBN:
(纸本)0470081562
SiCp/Al composites containing high volume fraction of SiC particles were fabricated by spark plasma sintering (SPS), and their thermophysical properties, such as thermal conductivity (TC) and coefficient of thermal expansion (CTE), were characterized. The principle of the fabrication was analyzed. Spark can be generated by electric field if the cavity in the green body is large enough. The melted Al by spark densify the compact which is similar to the pressure infiltration but with simple method. High relative density (R-D) of composites was successfully achieved through the optimization of sintering parameters. The measured TCs of SiCp/Al composites fabricated by SPS are higher than 195W/m·k.
C/BN laminated composites were obtained by hot-pressing, and the micro-structure and property of the sintered bodies were investigated. The results indicated that the relative density of the samples was 99%. SEM indic...
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C/BN laminated composites were obtained by hot-pressing, and the micro-structure and property of the sintered bodies were investigated. The results indicated that the relative density of the samples was 99%. SEM indicated that the combined interface between graphite and BN was good, and the transition of graphite and BN was gradual. The sintered bodies between the graphite and BN were destroyed at 1200°C after thermal shocks for 30 times. The tensile strength of materials reached 8.9 MPa.
C/BN laminated composites were obtained by spark plasma sintering. The relationship between sintering conditions, microstructure and properties were studied. The analysis of micro structure indicated that with increas...
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C/BN laminated composites were obtained by spark plasma sintering. The relationship between sintering conditions, microstructure and properties were studied. The analysis of micro structure indicated that with increasing the temperature and time of heat preservation the coalescent between graphite and BN was increased gradually. The bonding strength transformed from molecular gravitation to the union of molecular gravitation and mechanical strength. The circulation times of materials reached 40 times at sintering temperature of 1750°C for 5 min. The test of mechanical properties of the materials indicated that the largest tensile strength reached 18.2 MPa.
A single flat-plate Solid Oxide Fuel Cell (SOFC) with Ni-YSZ|YSZ|LSM configuration was developed, the test system and the fuel control system was established. The electrical properties were examined with H2 as the fue...
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A single flat-plate Solid Oxide Fuel Cell (SOFC) with Ni-YSZ|YSZ|LSM configuration was developed, the test system and the fuel control system was established. The electrical properties were examined with H2 as the fuel and the air as the oxidant in a temperature range of 800 to 1000°C. Results showed that the open-circuit voltage (OCV) was over 1.01 V, the maximum power density at 1000°C reached to 7.73 mW/cm2. It was found that the large ohmic losses of the electrolyte were the main factor responsible for the relative low output power density. The relations of OCV vs. operating temperature and OCV vs. fuel flow rates were also investigated.
Aluminum borate whiskers with TiB2 as borate source were prepared in this paper. The phase transformation process was analyzed by XRD and TG-DSC. The results indicate that TiB2 was decomposed into TiO 2 and B2O3 in th...
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Aluminum borate whiskers with TiB2 as borate source were prepared in this paper. The phase transformation process was analyzed by XRD and TG-DSC. The results indicate that TiB2 was decomposed into TiO 2 and B2O3 in the calcining process in the active [O] atmosphere. 2Al2O3.B2O3 was formed in the lower temperature with reaction of Al2O3 and B2O3, while 9Al2O3.2B 2O3 whiskers were grown by compensation of 2Al 2O3.B2O3 at higher temperature (above 1050°C).
The paper presents results on the mechanism of spark plasma sintering (SPS). First, the temperature distribution in the sample and the die in SPS were studied. Under certain conditions, the difference may reach a few ...
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ISBN:
(纸本)0470081562
The paper presents results on the mechanism of spark plasma sintering (SPS). First, the temperature distribution in the sample and the die in SPS were studied. Under certain conditions, the difference may reach a few hundreds of degrees of centigrade. Controlling of processing parameters can decrease the temperature difference. Second, the process of atomic diffusion due to the effect of the current was also studied. It was found that the atomic diffusion is enhanced at the interface between specimens in the SPS relative to hot pressing (HP). Third, we have utilized the SPS process to form transparent ceramics, porous metals and ceramics, and to effect welding of alloys.
SiCp/Al composites containing high volume fraction of SiC particles were fabricated by spark plasma sintering (SPS), and their thermophysical properties, such as thermal conductivity (TC) and coefficient of thermal ex...
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SiCp/Al composites containing high volume fraction of SiC particles were fabricated by spark plasma sintering (SPS), and their thermophysical properties, such as thermal conductivity (TC) and coefficient of thermal expansion (CTE), were characterized. High relative density (R-D) of composites was successfully achieved through the optimization of sintering parameters, such as sintering temperature, sintering pressure and heating rate. The measured TCs of SiCp/Al composites fabricated by SPS are higher than 195 W/m k, no matter the volume fraction of SiC particles is high or low as long as the R-D is higher than 95%. The measured CTEs of SiCp/Al composites are in good agreement with the estimated values based on Kerners model. The high volume fraction of SiCp/Al composites are a good candidate material to substitute for conventional thermal management materials in advanced electronic packages due to its tailorable thermophysical properties.
Lead-free Na0.5K0.5NbO3 (NKN) piezoelectric ceramics were fairly well densified at a relatively low temperature under atmospheric conditions. A relative density of 96-99 can be achieved by either using high-energy att...
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By using of high temperature XRD data, the high temperature structure behavior of corundum (α-Al2O3) with different crystal morphologies was studied by comparative crystal chemistry. It was revealed that cell paramet...
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By using of high temperature XRD data, the high temperature structure behavior of corundum (α-Al2O3) with different crystal morphologies was studied by comparative crystal chemistry. It was revealed that cell parameter (a, c) and Al-O bond length (LAl-O) of grain corundum were logarithmically increased because of thermal expansion, but that of the whisker corundum was linearly increased. The crystal lattice coefficient of thermal expansion (M) of the grain corundum was logarithmically increased almost in uniformity tendency, which was isotropy. On the contrary, that of the whisker corundum was linearly increased in whole tendency, the value M of cell parameter (a) is greater than cell parameter (c), which was anisotropy.
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