29 research outputs found
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Sealant materials for solid oxide fuels and other high-temperature ceramics
Glass-ceramic sealing materials have been developed with mechanical and chemical properties suitable for a variety of high-temperature applications. We have demonstrated the ability to tailor the thermal expansion coefficient between 8 and 12 x 10{sup -6}/{degrees}C, and the softening temperature can be adjusted such that the materials have suitable viscosities for a soft, compliant seal at temperatures ranging from 650 to 1000{degrees}C. These materials form excellent bonds to a variety of ceramics and metals during heating to the target operation temperature. They have limited reactivity with the fuel cell materials tested and are stable in both air and reducing environments
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Sealant materials for solid oxide fuel cells
The objective of this work is to complete the development of soft glass-ceramic sealants for the solid oxide fuel cell (SOFC). Among other requirements, the materials must soften at the operation temperature of the fuel cell (600--1,000 C) to relieve stresses between stack components, and their thermal expansions must be tailored to match those of the stack materials. Specific objectives included addressing the needs of industrial fuel cell developers, based on their evaluation of samples the authors supply, as well as working with commercial glass producers to achieve scaled-up production of the materials without changing their properties. Results from long-term stability testing, stability in voltage gradients, thermal expansion and softening, and scaled-up production methods are presented
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Advances in research for solid oxide fuel cells
Solid oxide fuel cells are attracting considerable interest among industrial organizations wanting to position themselves in a potentially important technology of the future. More than a dozen new organizations worldwide have begun SOFC development in the last few years. Most of this R and D activity is in the planar technology, because it represents a good compromise between the proven but IR-limited tubular configuration and the high-performance but difficult-to-fabricate monolithic structure. The challenges of developing the planar cell configurations are finding high-temperature edge and manifold seal materials that will make very flat ceramic trilayers of sufficiently large area, and minimize contact resistances in stacks of cells. Also, decreasing the operating temperature requires development of reliable thin-film fabrication methods for the electrolyte, and finding a metal with good oxidation resistance and a thermal expansion coefficient well matched with the different cell components. Finally, toughness and a thermal stress tolerance of stacks need to be improved
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Sealants for Solid Oxide Fuel Cells
Basic requirements for a sealant are good bonding to the materials of interest, chemical stability in the operating environment, and low gas permeability. For high-temperature operation as in Solid Oxide Fuel Cells (SOFCs), the sealant must also have a thermal expansion which is reasonably close to that of the other materials involved and must have some compliance, or softness, to allow for some mismatch between the components to be joined. In this paper, we discuss a family of glass-ceramic materials with mechanical, chemical, and electrical properties that are suitable for these demanding high-temperature applications
Derivation and characterization of cell cultures from the skin of the Indo-Pacific humpback dolphin Sousa chinensis
Changes in the interfacial tension of chlorinated solvents following flow through UK soils and shallow aquifer material
The interfacial tension (IFT) that arises at the interface between water and an immiscible organic liquid is a key parameter affecting the transport and subsequent fate of the organic liquid in water-saturated porous media. In this paper, data are presented that show how contact between a range of soil types and chlorinated hydrocarbon solvent (CHS) dense nonaqueous phase liquids (DNAPLs) can affect DNAPL/water IFT values. The soils examined are indicative of U.K. soil types and shallow aquifer materials. The solvents investigated were tetrachloroethylene (PCE) and trichloroethylene (TCE). Lab grade, recovered field DNAPL and industrial waste chlorinated solvent mixtures were used. The data from batch and column experiments invariably revealed that water/DNAPL IFT values change following contact with unsaturated soils. In the majority of cases, the IFT values increase following soil exposure. However, after contact with an organic-rich soil, the I FT of the lab grade solvents decreased. The experimental evidence suggests that these reductions are linked to the removal of organic material from the soil and its subsequent incorporation into the solvent. IFT increases in the case of lab solvents are shown to be linked to the removal of stabilizers (added by the manufacturers to obviate degradation) that are removed by adsorption to soil mineral surfaces. Similarly, it is conjectured that adsorption of surface-active compounds from the industrial waste samples to soil surfaces is responsible for increases in the IFT in these samples. Finally, it was observed that invading CHSs are capable of dissolving and subsequently mobilizing in-situ soil contaminants. GC/MS analysis revealed these mobilized soil contaminants to be polyaromatic hydrocarbons and phthalate esters