Materials & Coatings

Coated Glass for Transparent Heating Elements

This coated glass can be used in high-humidity and high-altitude applications such as architectural and aircraft windows. Applying an electric current to specially coated glass results in radiant heat energy. This process creates a transparent heating element with near- uniform surface temperatures. Manufacturing the heating element requires an ordinary pane of float glass. A fluorine-doped tin oxide coating (SnO2:F) measuring 0.25 micron thick is applied to one surface of the glass during fabrication. The coating conducts electricity, has a very tightly controlled resistance, has no appreciable color or structure, and is quite transparent. The coating has low emissivity properties that help contribute to the efficiency of the heated glass.

Posted in: Briefs, Materials, Heat transfer, Fabrication, Coatings, colorants, and finishes, Conductivity, Glass

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Method of Cross-Linking Aerogels Using a One-Pot Reaction Scheme

A document discusses a new, simplified method for cross-linking silica and other oxide aerogels, with a polymeric material to increase strength of such materials without adversely affecting porosity or low density. The usual process is long and arduous, requiring multiple washing and soaking steps to infiltrate oxide with the polymer precursor after gelation. Additionally, diffusion problems can result in aerogel monoliths that are not uniformly cross-linked.

Posted in: Briefs, Materials, Forming, Nanomaterials, Nanotechnology, Polymers

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CO₂ Sensors Based on Nanocrystalline SnO₂ Doped With CuO

Miniature CO2 sensors could be mass-produced inexpensively.Nanocrystalline tin oxide (SnO2) doped with copper oxide (CuO) has been found to be useful as an electrical-resistance sensory material for measuring the concentration of carbon dioxide in air. SnO2 is an n-type semiconductor that has been widely used as a sensing material for detecting such reducing gases as carbon monoxide, some of the nitrogen oxides, and hydrocarbons. Without doping, SnO2 usually does not respond to carbon dioxide and other stable gases. The discovery that the electrical resistance of CuO-doped SnO2 varies significantly with the concentration of CO2 creates opportunities for the development of relatively inexpensive CO2 sensors for detecting fires and monitoring atmospheric conditions. This discovery could also lead to research that could alter fundamental knowledge of SnO2 as a sensing material, perhaps leading to the development of SnO2-based sensing materials for measuring concentrations of oxidizing gases.

Posted in: Briefs, TSP, Materials, Sensors and actuators, Conductivity, Copper alloys, Nanotechnology, Refractory materials, Tin alloys

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Coating Reduces Ice Adhesion

Developed for the space shuttle, this coating may be used on aircraft and automobiles. The Shuttle Ice Liberation Coating (SILC) has been developed to reduce the adhesion of ice to surfaces on the space shuttle. SILC, when coated on a surface (foam, metal, epoxy primer, polymer surfaces), will reduce the adhesion of ice by as much as 90 percent as compared to the corresponding uncoated surface. This innovation is a durable coating that can withstand several cycles of ice growth and removal without loss of anti-adhesion properties.

Posted in: Briefs, Materials, Coatings, colorants, and finishes, Durability, Icing and ice detection, Reusable launch vehicles and shuttles

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Hybrid Multifoil Aerogel Thermal Insulation

Aerogel used in place of astroquartz makes lighter, more efficient insulation. This innovation blends the merits of multifoil insulation (MFI) with aerogel-based insulation to develop a highly versatile, ultra-low thermally conductive material called hybrid multifoil aerogel thermal insulation (HyMATI). The density of the opacified aerogel is 240 mg/cm3 and has thermal conductivity in the 20 mW/mK range in high vacuum and 25 mW/mK in 1 atmosphere of gas (such as argon) up to 800 ºC. It is stable up to 1,000 ºC. This is equal to commercially available high-temperature thermal insulation. The thermal conductivity of the aerogel is 36 percent lower compared to several commercially available insulations when tested in 1 atmosphere of argon gas up to 800 ºC.

Posted in: Briefs, TSP, Materials, Conductivity, Insulation, Nanomaterials

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Directed Growth of Carbon Nanotubes Across Gaps

Single-walled carbon nanotubes grow aligned along applied electric fields. An experiment has shown that when single- walled carbon nanotubes (SWNTs) are grown by chemical vapor deposition in the presence of an electric field of suitable strength, the nanotubes become aligned along the electric field. In an important class of contemplated applications, one would exploit this finding in fabricating nanotube transistors; one would grow SWNTs across gaps between electrodes that would serve, subsequently, as source and drain contacts during operation of the transistors.

Posted in: Briefs, TSP, Materials, Transistors, Fabrication, Chemicals, Nanomaterials

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Nanotip Carpets as Antireflection Surfaces

Reflectance less than 10–3 is readily achieved. Carpetlike random arrays of metal-coated silicon nanotips have been shown to be effective as antireflection surfaces. Now undergoing development for incorporation into Sun sensors that would provide guidance for robotic exploratory vehicles on Mars, nanotip carpets of this type could also have many uses on Earth as antireflection surfaces in instruments that handle or detect ultraviolet, visible, or infrared light.

Posted in: Briefs, TSP, Materials, Optics, Materials properties, Nanomaterials

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