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Sodium silicate/graphite conductive composites are prepared by mold pressing at room temperature. The effects of graphite content, size of graphite particles, mold pressing pressure, and mold pressing time on the electrical conductivity of composites are discussed. The density and the water content are composites with different graphite content and are also investigated. The optimized preparation conditions are determined. The results show that the electrical conductivity, the density, and the water content of sodium silicate/graphite composite bipolar plate for proton exchange membrane fuel cell (PEMFC) is >100s/cm, 1.8g/cm³, and 9 wt%, respectively. The density of this composite bipolar plate material is smaller than that of another bipolar plate. This composite bipolar plate material contains gel capillary pores and has sufficient hydrophilicity, which can humidify the proton exchange membrane during the operating process of PEMFC. [ABSTRACT FROM AUTHOR]

A mineral system of alite-calcium barium sulphoaluminate with high cementing characteristic was synthesized with chemical reagents. The influences of the mineral constituent, sintering temperature and some microelements on the performance of the clinker system were studied. Alite and calcium barium sulphoaluminate minerals can be synthesized at 1360∘C synchronously and can coexist in a clinker system. The suitable content of calcium barium sulphoaluminate in the clinker is less than 10 wt%. The compressive strength of some clinkers is nearly 90 MPa at 28 days age. The constituent, structure and morphology of the clinker minerals were analysized by means of XRD, SEM-EDS and light microscope. [ABSTRACT FROM AUTHOR]

The purpose of this research is to investigate the feasibility of the synthesis of platinum/multi-wall carbon nanotube (Pt/MWNT) catalysts and such catalysts' application in fuel cells. The as-received MWNTs were purified and decorated by pretreatment. Infrared-spectrum indicates the carboxylic (-COOH) and carbonyl (-C = O) groups were introduced on the surface of the MWNTs after pretreatment. These functional groups will act as anchor sites for the Pt deposition. Then the Pt particles in nano scale were deposited on the surface of MWNTs by reduction of a solution of hexachloroplatinic acid. Transmission electron microscopy examination reveals that Pt particles are attached to the surface of MWNTs. If as-received MWNTs are not pretreated in the proper way, the Pt particle aggregates are mostly found on the open end of MWNTs. Occasionally Pt penetrated inside the tube of MWNTs. The relationship between the Pt particle morphology and the conditions of pretreatment and reduction reaction is discussed. After heat treatment, Pt particles recrystallized to form the Pt/MWNT catalysts. The Pt/MWNT catalysts were applied to a single cell and the test result shows a promising future of these catalysts with low Pt loading when applied in proton exchange membrane fuel cells (PEMFCs). [ABSTRACT FROM AUTHOR]

The synthesis of filled skutterudite compounds (Ce or Y) yFe xCo4- xSb12, through a solid state reaction using chloride of Ce or Y, high purity powder of Co, Fe, and Sb as starting materials, was investigated. (Ce or Y) yFe xCo4- xSb12 ( x = 0 1.0, y = 0 0.15) compounds were obtained at 850 1 123 K. The results of Rietveld analysis demonstrate that (Ce or Y) yFe xCo4- xSb12 synthesized by a solid state reaction possesses a filled skutterudite structure. The filling fraction of Ce or Y obtained by Rietveld analysis agrees well with the composition obtained by chemical analysis. The lattice constant of Ce yFe xCo4- xSb12 increases with increasing substitution of Fe at Co sites, and with an increasing Ce filling fraction in the Sb-dodecahedron voids. The lattice thermal conductivity of (Ce or Y) yFe xCo4- xSb12 decreases significantly with an increasing Ce or Y filling fraction in the voids and with substitution of Fe at Co sites. [ABSTRACT FROM AUTHOR]

This paper deals with the crystallization of MgO during sintering of Si3N4-MgO-CeO2 ceramics. At the initial stage of sintering (1450–1550°C), MgO-CeO2 reacts with free silica to form sufficient liquid phase to densify Si3N4 into nearly full density ceramics; at final stage (1600–1800°C), the crystallization of MgO reduces the amount of glassy phase which is harmful to the high-temperature properties. MgO-CeO2 is found to be an excellent sintering aid for Si3N4. [ABSTRACT FROM AUTHOR]