Manufacturing & Prototyping

Separation and Sealing of a Sample Container Using Brazing

This process is an alternative to a prior explosive welding process. A special double-wall container and a process for utilizing the container are being developed to enable (1) acquisition of a sample of material in a “dirty” environment that may include a biological and/or chemical hazard; (2) sealing a lid onto the inner part of the container to hermetically enclose the sample; (3) separating the resulting hermetic container from the dirty environment; and (4) bringing that hermetic container, without any biological or chemical contamination of its outer surface, into a clean environment. The process is denoted “S3B” (separation, seaming, and sealing using brazing) because sealing of the sample into the hermetic container, separating the container from the dirty environment, and bringing the container with a clean outer surface into the clean environment are all accomplished simultaneously with a brazing operation. This container and process were conceived as a superior alternative to the double-wall container and process described in “Explosion Welding for Hermetic Containerization” (NPO-20868), NASA Tech Briefs, Vol. 27, No. 8 (August 2003), page 46. As in the previously reported case, the present container and process were originally intended to be used to return samples from Mars to Earth, but could also be used on Earth to store and transport material samples acquired in environments that contain biological and/or chemical hazards.

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Fabrication of Buried Nanochannels From Nanowire Patterns

Sacrificial nanowires are buried, then etched away to form buried channels. A method of fabricating channels having widths of tens of nanometers in silicon substrates and burying the channels under overlying layers of dielectric materials has been demonstrated. With further refinement, the method might be useful for fabricating nanochannels for manipulation and analysis of large biomolecules at single-molecule resolution. Unlike in prior methods, burying the channels does not involve bonding of flat wafers to the silicon substrates to cover exposed channels in the substrates. Instead, the formation and burying of the channels are accomplished in a more sophisticated process that is less vulnerable to defects in the substrates and less likely to result in clogging of, or leakage from, the channels.

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Diamond Smoothing Tools

Machined surfaces could be made much smoother. Diamond smoothing tools have been proposed for use in conjunction with diamond cutting tools that are used in many finish-machining operations. Diamond machining (including finishing) is often used, for example, in fabrication of precise metal mirrors.

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A Method of Assembling Compact Coherent Fiber-Optic Bundles

The method is based on hexagonal close packing. A method of assembling coherent fiber-optic bundles in which all the fibers are packed together as closely as possible is undergoing development. The method is based straightforwardly on the established concept of hexagonal close packing; hence, the development efforts are focused on fixtures and techniques for practical implementation of hexagonal close packing of parallel optical fibers.

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Manufacturing Diamond Under Very High Pressure

Pure or doped diamond is crystallized from molten carbon and in solid state. A process for manufacturing bulk diamond has been made practical by the invention of the High Pressure and Temperature Apparatus capable of applying the combination of very high temperature and high pressure needed to melt carbon in a sufficiently large volume. The rate of growth achievable in this process is about ten times the rate achievable in older processes. Depending on the starting material and temperature-and-pressure schedule, this process can be made to yield diamond in any of a variety of scientifically and industrially useful forms, including monocrystalline, polycrystalline, pure, doped, and diamond composite. (Doping makes it possible to impart desired electrical and optical properties, including semiconductivity and color.) The process can also be used to make cubic boron nitride.

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Film/Adhesive Processing Module for Fiber-Placement Processing of Composites

Films, foils, or adhesives may be interleaved while fiber-placing composite material structures. An automated apparatus has been designed and constructed that enables the automated lay-up of composite structures incorporating films, foils, and adhesives during the automated fiberplacement process. This apparatus, denoted a film module, could be used to deposit materials in film or thin sheet form either simultaneously when laying down the fiber composite article or in an independent step. Examples of materials that may be processed with this device include structural core and joining adhesives, permeation barrier films/foils, surfacing films, lightning-strike materials and IVHM (Integral Vehicle Health Monitoring) arrays. The use of this technology will reduce composite fabrication time and will allow for new concepts/ designs to be considered for fiber-placed composite structures.

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Radiation-Shielding Polymer/Soil Composites

Radiation shields could be fabricated in situ at relatively low cost. It has been proposed to fabricate polymer/soil composites primarily from extraterrestrial resources, using relatively lowenergy processes, with the original intended application being that habitat structures constructed from such composites would have sufficient structural integrity and also provide adequate radiation shielding for humans and sensitive electronic equipment against the radiation environment on the Moon and Mars. The proposal is a response to the fact that it would be much less expensive to fabricate such structures in situ as opposed to transporting them from Earth.

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