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Electrophoretic Deposition on Porous Non-Conductors

EPD is simplified and made more widely applicable. A method of electrophoretic deposition (EPD) on substrates that are porous and electrically non-conductive has been invented. Heretofore, in order to perform an EPD, it has been necessary to either (1) use a substrate material that is inherently electrically conductive or (2) subject a non-conductive substrate to a thermal and/or chemical treatment to render it conductive.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Freeze Tape Casting of Functionally Graded Porous Ceramics

Pore structures can be tailored in ways heretofore impossible. Freeze tape casting is a means of making preforms of ceramic sheets that, upon subsequent completion of fabrication processing, can have anisotropic and/or functionally graded properties that notably include aligned and graded porosity. Freeze tape casting was developed to enable optimization of the microstructures of porous ceramic components for use as solid oxide electrodes in fuel cells: Through alignment and grading of pores, one can tailor surface areas and diffusion channels for flows of gas and liquid species involved in fuel-cell reactions. Freeze tape casting offers similar benefits for fabrication of optimally porous ceramics for use as catalysts, gas sensors, and filters.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Hydrogen Peroxide Concentrator

Water is removed through selectively permeable membranes. A relatively simple and economical process and apparatus for concentrating hydrogen peroxide from aqueous solution at the point of use have been invented. The need for this or a similar invention arises for the following reasons:

Posted in: Manufacturing & Prototyping, Briefs

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Rapid and Quiet Drill

This is an all-ultrasonic variant of previously reported ultrasonic/sonic drills. The figure depicts selected aspects of the rapid and quiet drill (RAQD), which is a prototype apparatus for drilling concrete or bricks. The design and basic principle of operation of the RAQD overlap, in several respects, with those of ultrasonic/sonic drilling and coring apparatuses described in a number of previous NASA Tech Briefs articles. The main difference is that whereas the actuation scheme of the prior apparatuses is partly ultrasonic and partly sonic, the actuation scheme of the RAQD is purely ultrasonic. Hence, even though the RAQD generates considerable sound, it is characterized as quiet because most or all of the sound is above the frequency range of human hearing.

Posted in: Manufacturing & Prototyping, Briefs

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Thermally Conductive Metal-Tube/Carbon-Composite Joints

Modified solder joints accommodate differential thermal expansion. An improved method of fabricating joints between metal and carbon-fiber-based composite materials in lightweight radiators and heat sinks has been devised. Carbon-fiber-based composite materials have been used in such heat-transfer devices because they offer a combination of high thermal conductivity and low mass density. Metal tubes are typically used to carry heat-transfer fluids to and from such heat-transfer devices. The present fabrication method helps to ensure that the joints between the metal tubes and the composite-material parts in such heat-transfer devices have both (1) the relatively high thermal conductances needed for efficient transfer of heat and (2) the flexibility needed to accommodate differences among thermal expansions of dissimilar materials in operation over wide temperature ranges.

Posted in: Manufacturing & Prototyping, Briefs

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Electrical Monitoring of Thicknesses of Semiconductor Wafers

Electrical fuses would be implanted at depths corresponding to desired thicknesses. A technique based on electrical-continuity measurements has been proposed as a means of monitoring and controlling the thicknesses of semiconductor wafers during lapping, polishing, and etching. The technique is expected to contribute to the development of microelectromechanical systems by making it possible to lap and polish wafers with precision greater than has been achieved previously, thereby further making it possible to fabricate wafers of unprecedented thinness (thicknesses of 5 µm or possibly even less). Unlike some prior techniques for measuring the thicknesses of semiconductor wafers, this technique does not entail the timeconsuming intermittent stopping of processing to take measurements. Also, in comparison with most prior techniques, this technique offers the potential for greater precision at lower cost.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Two Techniques for Removing Core-Drill Debris

Both techniques contribute savings in time and money. Two alternative techniques make it possible to remove core-drill debris more rapidly and efficiently than was previously possible. Either technique is a vast improvement over the prior art. For industries in which ultrasonic core drills are used, these two techniques are expected to result in savings of time and money.

Posted in: Manufacturing & Prototyping, Briefs

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