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.
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.
The processes of the coupling graft of -Si(OCH3)3 groups between 7-aminopropyl trimethoxysilane molecules and iron microparticles and the preparation of Fe/SiO2 core-shell composite particles in the alcohol-alkali-wat...
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The processes of the coupling graft of -Si(OCH3)3 groups between 7-aminopropyl trimethoxysilane molecules and iron microparticles and the preparation of Fe/SiO2 core-shell composite particles in the alcohol-alkali-water solution were investigated in the paper. The as-prepared and heat-treated composite particles were characterized with XRD, SEM, and pickling tests. The results showed that the formation of free SiO2 could be effectively prevented by decreasing the rate of adding ammonia, and that Fe/SiO2 core-shell composite particles almost without free SiO2 were successfully fabricated with a controlling rate about 5 drops of ammonia per minute. The optimal temperature range for the densification of SiO2 nanoshell is about 600 [similar to] 700 °C. The SiO2 nanoshells were badly melt and dropped off when the composite particles were heat-treated at 900 °C. The acid resistance of the composite particles increases as the temperature rose from 200 °C to 700 °C.
Mullite-based nanocomposite powders with embedded iron nanoparticles were synthesized by reduction of sol-gel prepared Al5.4Fe 0.6Si2O13 solid solution in hydrogen. Structural characterization studied by TEM revealed ...
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ISBN:
(纸本)0470080337
Mullite-based nanocomposite powders with embedded iron nanoparticles were synthesized by reduction of sol-gel prepared Al5.4Fe 0.6Si2O13 solid solution in hydrogen. Structural characterization studied by TEM revealed that the intra-granular iron nanoparticles along with inter-type iron grains were obtained in mullite matrix. The magnetic properties of nanocomposite powders after reduction at 1200°C were measured by SQUID. It suggests that the intergranular and intragranular α-iron nanoparticles had the ferromagnetic and superparamagnetic behavior at room temperature, respectively. Dense Mullite-based iron composites were prepared from the nanocomposite powders reduced at different temperatures by hot pressing. The mechanical and magnetic properties were strongly affected by the reduction temperature. Flexural strength of mullite based iron nanocomposite reduced at 1200°C and successively hot pressed at 1650°C is one times higher than monothetic mullite. Furthermore, dense composites also behave ferromagnetic property at room temperature.
A bulk metal/ceramic composite material with a honeycomb-like micro-cell structure has been prepared by sintering the spherical Al90Mn9Ce1 alloy powders clad by Al2O3 nano-powder with the spark plasma sintering (SPS) ...
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A bulk metal/ceramic composite material with a honeycomb-like micro-cell structure has been prepared by sintering the spherical Al90Mn9Ce1 alloy powders clad by Al2O3 nano-powder with the spark plasma sintering (SPS) technique. The as-prepared material consists of Al90Mn9Ce1 alloy cell and closed Al2O3 ceramic cell wall. The diameter of the cells is about 20―40 μm, while a thickness of the cell wall is about 1―2 μm. The ultimate compressive strength of the as-sintered materials is about 514 MPa, while its fracture strain is up to about 0.65 %. This composite material might possess good anti-corrosion, thermal endurance and other potential properties due to its unique microstructure. The result shows that the Al90Mn9Ce1/Al2O3 composite powders can be sintered by spark plasma sintering technique despite the large difference in their sintering temperature. This work offers a way of designing and preparing metal/ceramic composite material with functional property.
The dynamic behaviour of ceramic particle reinforced metal matrix composites (MMCs) is a key to its application. In this paper, the computational micro-mechanics method (CMM) is used to simulate SHPB experiment of MMC...
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The dynamic behaviour of ceramic particle reinforced metal matrix composites (MMCs) is a key to its application. In this paper, the computational micro-mechanics method (CMM) is used to simulate SHPB experiment of MMCs. The numerical SHPB's specimen of MMCs is firstly generated by CMM. Then, for verifying the correction of numerical experiment, the Al2O 3/6061-T6Al composite is used to carry out numerical experiment, and the Johnson-Holmquist (JH-2) damage model is used to describe the ceramic mechanics behaviour, and a comparison between this numerical method and Unit Cell analytical model is carried out. Lastly, the dynamic behaviour of T6061Al/Al2O3 is investigated by this method.
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.
Super-fine mesophase powder (SFMP) was prepared from a coal tar pitch accompanying mesocarbon microbeads (MCMB) and then was manufactured into high density and isotropic carbon (HDIC) bulks. The influence of ß-re...
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ISBN:
(纸本)9781605600390
Super-fine mesophase powder (SFMP) was prepared from a coal tar pitch accompanying mesocarbon microbeads (MCMB) and then was manufactured into high density and isotropic carbon (HDIC) bulks. The influence of ß-resin content in SFMP precursors and sintering conditions has been studied on the performance of derived HDIC. It has found that, to obtain HDIC with excellent mechanical performance, suitable ß-resin content in SFMP and sintering rate are required. In the sintering range of 470°C-1000°C, higher temperature facilitate the formation of compact HDIC with high flexural strength. Volume shrinkage during sintering can be adopted to val-ate approximately the mechanical performance.
Spark or not in insulator materials sintered by pulse electric current or spark plasma sintering is still in dispute. In this paper, the electric field in the graphite die was calculated by Maxwell theory. The calcula...
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ISBN:
(纸本)0470081562
Spark or not in insulator materials sintered by pulse electric current or spark plasma sintering is still in dispute. In this paper, the electric field in the graphite die was calculated by Maxwell theory. The calculated results indicate that the distribution of electric field is in heterogeneous. The intensity of electric field is enhanced at the centre area contacting with punch surface, weakened in circumference contacting with the die. It is deduced from the calculated results that the most possible area to generate spark lies on the punch surface if any spark could be generated in the sintered sample. Some experimental results are accordance with the calculated distribution of electric field and the spark of punch surface.
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).
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