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Iodine-Compatible Hall Effect Thruster
Precision Assembly of Systems on Surfaces (PASS)
Development of a Novel Electrospinning System with Automated Positioning and Control Software
2016 Create The Future Design Contest Open For Entries
Clamshell Sampler
Shape Memory Alloy Rock Splitter
Deployable Extra-Vehicular Activity Platform (DEVAP) for Planetary Surfaces
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Environmentally Safer, Less Toxic Fire-Extinguishing Agents

Water droplets would be microencapsulated in flame-retardant polymers. Fire-extinguishing agents comprising microscopic drops of water micro- encapsulated in flame-retardant polymers have been proposed as effective, less toxic, non-ozone- depleting, non-global- warming alternatives to prior fire-extinguishing agents. Among the prior fire-extinguishing agents are halons (various halocarbon fluids), which are toxic and contribute both to depletion of upper- atmospheric ozone and to global warming. Other prior fire-extinguishing agents are less toxic and less environmentally harmful but, in comparison with halons, are significantly less effective in extinguishing fires.

Posted in: Briefs

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Switching and Rectification in Carbon-Nanotube Junctions

Research shows promise for nanoscale electronic devices. Figure 1. Symmetric and Asymmetric Carbon-Nanotube Multiterminal carbon-nanotube junctions are under investigation as candidate components of nanoscale electronic devices and circuits. Three-terminal "Y" junctions of carbon nanotubes (see Figure 1) have proven to be especially interesting because (1) it is now possible to synthesize them in high yield in a controlled manner and (2) results of preliminary experimental and theoretical studies suggest that such junctions could exhibit switching and rectification properties.

Posted in: Briefs, TSP

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Scandia-and-Yttria-Stabilized Zirconia for Thermal Barriers

These compositions offer thermal stability greater than that of yttria-stabilized zirconia. Zirconia stabilized with both scandia and yttria in suitable proportions has shown promise of being a superior thermal-barrier coating (TBC) material, relative to zirconia stabilized with yttria only. More specifically, a range of compositions in the zirconia/scandia/yttria material system has been found to afford increased resistance to deleterious phase transformations at temperatures high enough to cause deterioration of yttria- stabilized zirconia.

Posted in: Briefs, TSP

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Single-Vector Calibration of Wind-Tunnel Force Balances

Improved data quality with an order of magnitude reduction in cost and calibration cycle time over prior methods. An improved method of calibrating a wind-tunnel force balance involves the use of a unique load application system integrated with formal experimental design methodology. The Single-Vector Force Balance Calibration System (SVS) overcomes the productivity and accuracy limitations of prior calibration methods.

Posted in: Briefs

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Microgyroscope With Vibrating Post as Rotation Transducer

Unlike in prior vibratory microgyroscopes, there is no cloverleaf structure. The figure depicts a micromachined silicon vibratory gyroscope that senses rotation about its z axis. The rotation-sensitive vibratory element is a post oriented (when at equilibrium) along the z axis and suspended at its base by thin, flexible silicon bands oriented along the x and y axes, respectively. Unlike in the vibratory microgyroscopes described in the immediately preceding article ["Cloverleaf Vibratory Microgyroscope With Integrated Post" (NPO-20688)] and other previous articles in NASA Tech Briefs, the rotation-sensitive vibratory element does not include a cloverleaf-shaped structure that lies (when at equilibrium) in the x-y plane.

Posted in: Briefs, TSP

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Cloverleaf Vibratory Microgyroscope With Integrated Post

Modifications should lead to greater unit-to-unit consistency. A modified design and fabrication sequence has been devised to improve the performance of a cloverleaf vibratory microgyroscope that includes an axial rod or post rigidly attached to the center of the cloverleaf structure. The basic concepts of cloverleaf vibratory microgyroscopes, without and with rods or posts, were described in two prior articles in NASA Tech Briefs, Vol. 21, No. 9 (September 1997): "Micromachined Planar Vibratory Microgyroscopes" (NPO-19713), page 68 and "Planar Vibratory Microgyroscope: Alternative Configuration" (NPO-19714), page 70. As described in more detail in the second-mentioned prior article, the cloverleaf-shaped structure and the rod or post are parts of a vibratory element that senses rotation via the effect of the Coriolis force upon its vibrations.

Posted in: Briefs, TSP

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Cryogenic Temperature-Gradient Foam/Substrate Tensile Tester

Tensile strengths are measured under more nearly realistic conditions. The figure shows a fixture for measuring the tensile strength of the bond between an aluminum substrate and a thermally insulating polymeric foam. The specimen is meant to be representative of insulating foam on an aluminum tank that holds a cryogenic liquid. Prior to the development of this fixture, tensile tests of this type were performed on foam/substrate specimens immersed in cryogenic fluids. Because the specimens were cooled to cryogenic temperatures throughout their thicknesses, they tended to become brittle and to fracture at loads below true bond tensile strengths.

Posted in: Briefs, TSP

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