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Diamond Machining of an Off-Axis Biconic Aspherical Mirror

Complex shapes can be produced at relatively low costs. Two diamond-machining methods have been developed as part of an effort to design and fabricate an off-axis, biconic ellipsoidal, concave aluminum mirror for an infrared spectrometer at the Kitt Peak National Observatory. Beyond this initial application, the methods can be expected to enable satisfaction of requirements for future instrument mirrors having increasingly complex (including asymmetrical), precise shapes that, heretofore, could not readily be fabricated by diamond machining or, in some cases, could not be fabricated at all.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Alternative Packaging for Back-Illuminated Imagers

Electrical contacts are made accessible from the back side. An alternative scheme has been conceived for packaging of silicon- based back-illuminated, back- side-thinned complementary metal oxide/semiconductor (CMOS) and charge-coupled-device image-detector integrated circuits, including an associated fabrication process. This scheme and process are complementary to those described in “Making a Back- Illuminated Imager With Back-Side Connections” (NPO-42839), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 38.

Posted in: Manufacturing & Prototyping, Briefs

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Improved Photoresist Coating for Making CNT Field Emitters

This technique could contribute to development of cold cathodes for diverse applications. An improved photoresist-coating technique has been developed for use in the fabrication of carbon-nanotube- (CNT)- based field emitters of the type described in “Fabrication of Improved Carbon- Nanotube Field Emitters” (NPO-44996), NASA Tech Briefs, Vol. 32, No. 4 (April 2008), page 50. The improved photoresist- coating technique overcomes what, heretofore, has been a major difficulty in the fabrication process. This technique is expected to contribute to the realization of high-efficiency field emitters (cold cathodes) for diverse systems and devices that could include gas-ionization systems, klystrons, flat-panel display devices, cathode-ray tubes, scanning electron microscopes, and x-ray tubes.

Posted in: Manufacturing & Prototyping, Briefs

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Composite Layer Manufacturing With Fewer Interruptions

An improved version of composite layer manufacturing (CLM) has been invented. CLM is a type of solid freeform fabrication (SFF) — an automated process in which a three-dimensional object is built up, point-by-point, through extrusion of a matrix/fiber composite-material precursor. The elements of SFF include (1) preparing a matrix resin in a form in which it will solidify subsequently, (2) mixing fibers and matrix material to form a continuous preimpregnated tow (also called “towpreg”), and (3) dispensing the towpreg from a nozzle onto a base while moving the nozzle to form the dispensed material into a series of patterned layers of controlled thickness.

Posted in: Manufacturing & Prototyping, Briefs

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Machined Titanium Heat-Pipe Wick Structure

Wicks are fabricated separately, then inserted in tubes. Wick structures fabricated by machining of titanium porous material are essential components of lightweight titanium/ water heat pipes of a type now being developed for operation at temperatures up to 530 K in high-radiation environments. In the fabrication of some prior heat pipes, wicks have been made by extruding axial grooves into aluminum — unfortunately, titanium cannot be extruded. In the fabrication of some other prior heat pipes, wicks have been made by in-situ sintering of metal powders shaped by the use of forming mandrels that are subsequently removed, but in the specific application that gave rise to the present fabrication method, the required dimensions and shapes of the heat-pipe structures would make it very difficult if not impossible to remove the mandrels due to the length and the small diameter.

Posted in: Manufacturing & Prototyping, Briefs

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Improved Joining of Metal Components to Composite Structures

Uncured composite material is intertwined with metal studs, then cured. Systems requirements for complex spacecraft drive design requirements that lead to structures, components, and/or enclosures of a multi-material and multifunctional design. The varying physical properties of aluminum, tungsten, Invar, or other high-grade aerospace metals when utilized in conjunction with lightweight composites multiply system level solutions. These multi-material designs are largely dependent upon effective joining techniques, which create a “monolithic,” well-integrated and seamlessly functional structure.

Posted in: Manufacturing & Prototyping, Briefs

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System for Removing Pollutants From Incinerator Exhaust

A system for removing pollutants — primarily sulfur dioxide and mixed oxides of nitrogen (NOx) — from incinerator exhaust has been demonstrated. The system is also designed secondarily to remove particles, hydrocarbons, and CO. The system is intended for use in an enclosed environment, for which a prior NOx-and-SO2-removal system designed for industrial settings would not be suitable. The incinerator exhaust first encounters a cyclone separator, a primary heat exchanger, and a fabric filter that, together, remove particles and reduce the temperature to 500 °C. The exhaust then passes through a porous bed, maintained at ≈ 450 °C, that contains Na2CO3, which absorbs SO2.

Posted in: Manufacturing & Prototyping, Briefs

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