Materials & Coatings

Composite Cathodes for Dual-Rate Li-Ion Batteries

A battery could have both high charge capacity and high rate capacity. Composite-material cathodes that enable Li-ion electrochemical cells and batteries to function at both high energy densities and high discharge rates are undergoing development. Until now, using commercially available cathode materials, it has been possible to construct cells that have either capability for high-rate discharge or capability to store energy at average or high density, but not both capabilities. However, both capabilities are needed in robotic, standby-power, and other applications that involve duty cycles that include long-duration, low-power portions and short-duration, high-power portions.

Posted in: Briefs, TSP, Materials


Nickel-Based Superalloy Resists Embrittlement by Hydrogen

This alloy also exhibits high strength and ductility. A nickel-based superalloy that resists embrittlement by hydrogen more strongly than does nickel alloy 718 has been developed. Nickel alloy 718 is the most widely used superalloy. It has excellent strength and resistance to corrosion as well as acceptably high ductility, and is recognized as the best alloy for many high- temperature applications. However, nickel alloy 718 is susceptible to embrittlement by hydrogen and to delayed failure and reduced tensile properties in gaseous hydrogen. The greater resistance of the present nickel- based superalloy to adverse effects of hydrogen makes this alloy a superior alternative to nickel alloy 718 for applications that involve production, transfer, and storage of hydrogen, thereby potentially contributing to the commercial viability of hydrogen as a clean-burning fuel.

Posted in: Briefs, Materials, Hydrogen storage, Product development, Metallurgy, Nickel alloys


Chemical Passivation of Li⁺-Conducting Solid Electrolytes

Such passivation could enable long-life lithium rechargeable cells.Plates of a solid electrolyte that exhibits high conductivity for positive lithium ions can now be passivated to prevent them from reacting with metallic lithium. Such passivation could enable the construction and operation of high-performance, long-life lithium-based rechargeable electrochemical cells containing metallic lithium anodes. The advantage of this approach, in comparison with a possible alternative approach utilizing lithium-ion graphitic anodes, is that metallic lithium anodes could afford significantly greater energy-storage densities.

Posted in: Briefs, TSP, Materials


Self-Deploying Trusses Containing Shape-Memory Polymers

Compacted structures can be used in shelters for hostile environments. Composite truss structures are being developed that can be compacted for stowage and later deploy themselves to full size and shape. In the target applications, these “smart” structures will precisely self-deploy and support a large, lightweight space-based antenna. Self-deploying trusses offer a simple, light, and affordable alternative to articulated mechanisms or inflatable structures. The trusses may also be useful in such terrestrial applications as variable-geometry aircraft components or shelters that can be compacted, transported, and deployed quickly in hostile environments.

Posted in: Briefs, Materials, Antennas, Storage, Composite materials, Smart materials, Spacecraft


Refractory Ceramic Foams for Novel Applications

Properties could be tailored for specific uses as insulators, filters, or catalyst supports. Workers at NASA Ames Research center are endeavoring to develop durable, oxidation- resistant, foam thermal protection systems (TPSs) that would be suitable for covering large exterior spacecraft surfaces, would have low to moderate densities, and would have temperature capabilities comparable to those of carbon- based TPSs [reusable at 3,000 °F (≈1,650 °C)] with application of suitable coatings. These foams may also be useful for repairing TPSs while in orbit. Moreover, on Earth as well as in outer space, these foams might be useful as catalyst supports and filters.

Posted in: Briefs, TSP, Materials, Ceramics, Foams, Insulation, Refractory materials, Durability


Molecules for Fluorescence Detection of Specific Chemicals

These molecules could be used in the detection of chemical warfare agents. A family of fluorescent dye molecules has been developed for use in “on-off” fluorescence detection of specific chemicals. By themselves, these molecules do not fluoresce. However, when exposed to certain chemical analytes in liquid or vapor forms, they do fluoresce (see figure). These compounds are amenable to fixation on or in a variety of substrates for use in fluorescence-based detection devices: they can be chemically modified to anchor them to porous or non-porous solid supports or can be incorporated into polymer films. Potential applications for these compounds include detection of chemical warfare agents, sensing of acidity or alkalinity, and fluorescent tagging of proteins in pharmaceutical research and development. These molecules could also be exploited for use as two-photon materials for photodynamic therapy in the treatment of certain cancers and other diseases.

Posted in: Briefs, TSP, Materials, Sensors and actuators, Medical equipment and supplies, Chemicals, Test equipment and instrumentation


Fuel-Cell Electrolytes Based on Organosilica Hybrid Proton Conductors

A new membrane composite material that combines an organosilica proton conductor with perfluorinated Nafion material to achieve good proton conductivity and high-temperature performance for membranes used for fuel cells in stationary, transportation, and portable applications has been developed.

Posted in: Briefs, Materials, Fuel cells, Composite materials, Conductivity, Electrolytes


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