Manufacturing & Prototyping

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: Briefs, Manufacturing & Prototyping, Water, Fabrication, Heat resistant alloys, Titanium, Parts, Hoses
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Sealing and External Sterilization of a Sample Container

This method would enable safe transport of a biologically hazardous sample.

A method of (1) sealing a sample of material acquired in a possibly biologically contaminated (“dirty”) environment into a hermetic container, (2) sterilizing the outer surface of the container, then (3) delivering the sealed container to a clean environment has been proposed. This method incorporates the method reported in “Separation and Sealing of a Sample Container Using Brazing” (NPO-41024), NASA Tech Briefs, Vol. 31, No. 8 (August 2007), page 42. Like the previously reported method, the method now proposed was originally intended to be used to return samples from Mars to Earth, but could also be used on Earth to transport material samples acquired in environments that contain biological hazards and/or, in some cases, chemical hazards.

Posted in: Briefs, Manufacturing & Prototyping, Biological sciences, Containers
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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: Briefs, Manufacturing & Prototyping, Exhaust emissions, Nitrogen oxides
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Templates for Deposition of Microscopic Pointed Structures

These structures can be used as field emitters in plasma television screens.

Templates for fabricating sharply pointed microscopic peaks arranged in nearly regular planar arrays can be fabricated by a relatively inexpensive technique that has recently been demonstrated. Depending on the intended application, a semiconducting, insulating, or metallic film could be deposited on such a template by sputtering, thermal evaporation, pulsed laser deposition, or any other suitable conventional deposition technique. Pointed structures fabricated by use of these techniques may prove useful as photocathodes or field emitters in plasma television screens. Selected peaks could be removed from such structures and used individually as scanning tips in atomic force microscopy or mechanical surface profiling.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Microscopy, Fabrication
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Making Superconducting Welds Between Superconducting Wires

Parts of a superconducting circuit can be made from different metals.

A technique for making superconducting joints between wires made of dissimilar superconducting metals has been devised. The technique is especially suitable for fabrication of superconducting circuits needed to support persistent electric currents in electromagnets in diverse cryogenic applications. Examples of such electromagnets include those in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) systems and in superconducting quantum interference devices (SQUIDs).

Posted in: Briefs, TSP, Manufacturing & Prototyping, Electromagnetic compatibility, Wiring, Fabrication, Welding, Conductivity
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Method for Thermal Spraying of Coatings Using Resonant-Pulsed Combustion

High-volume, high-velocity surface deposition allows protective metal coatings to be applied to otherwise vulnerable surfaces.

A method has been devised for high-volume, high-velocity surface deposition of protective metallic coatings on otherwise vulnerable surfaces. Thermal spraying is used whereby the material to be deposited is heated to the melting point by passing through a flame. Rather than the usual method of deposition from the jet formed from the combustion products, this innovation uses non-steady combustion (i.e. high- frequency, periodic, confined bursts), which generates not only higher temperatures and heat transfer rates, but exceedingly high impingement velocities an order of magnitude higher than conventional thermal systems. Higher impingement rates make for better adhesion. The high heat transfer rates developed here allow the deposition material to be introduced, not as an expensive powder with high surface-area-to-volume, but in convenient rod form, which is also easier and simpler to feed into the system. The nonsteady, resonant combustion process is self-aspirating and requires no external actuation or control and no high-pressure supply of fuel or air.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Heat transfer, Spraying, Metals, Combustion and combustion processes
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Capillography of Mats of Nanofibers

These mats can be the basis of small devices and instruments.

Capillography (from the Latin capillus, “hair”, and the Greek graphein, “to write”) is a recently conceived technique for forming mats of nanofibers into useful patterns. The concept was inspired by experiments on carpetlike mats of multiwalled carbon nanotubes. Capillography may have the potential to be a less-expensive, less- time-consuming alternative to electron- beam lithography as a means of nanoscale patterning for the fabrication of small devices and instruments.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Fabrication, Fibers, Nanomaterials
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Improved Gas Filling and Sealing of an HC-PCF

Compact hermetic joint is formed to seal connectorized all-fiber gas reference cell.

An improved packaging approach has been devised for filling a hollow-core photonic-crystal fiber (HC-PCF) with a gas, sealing the HC-PCF to retain the gas, and providing for optical connections and, optionally, a plumbing fitting for changing or augmenting the gas filling. Gas-filled HC-PCFs can be many meters long and have been found to be attractive as relatively compact, lightweight, rugged alternatives to conventional gas-filled glass cells for use as molecular-resonance frequency references for stabilization of lasers in some optical-metrology, lidar, optical-communication, and other advanced applications. Prior approaches to gas filling and sealing of HC-PCFs have involved, variously, omission of any attempt to connectorize the PCF, connectorization inside a vacuum chamber (an awkward and expensive process), or temporary exposure of one end of an HC-PCF to the atmosphere, potentially resulting in contamination of the gas filling. Prior approaches have also involved, variously, fusion splicing of HC-PCFs with other optical fibers or other termination techniques that give rise to Fresnel reflections of about 4 percent, which results in output intensity noise.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Fiber optics, Gases, Refractory materials, Reliability
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Thermal Spray Formation of Polymer Coatings

This innovation forms a sprayable polymer film using powdered precursor materials and an in-process heating method. This device directly applies a powdered polymer onto a substrate to form an adherent, mechanically-sound, and thickness-regulated film. The process can be used to lay down both fully dense and porous, e.g., foam, coatings. This system is field-deployable and includes power distribution, heater controls, polymer constituent material bins, flow controls, material transportation functions, and a thermal spray apparatus.

Posted in: Briefs, Manufacturing & Prototyping, Coatings, colorants, and finishes, Polymers
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Fabricating Large-Area Sheets of Single-Layer Graphene by CVD

Such sheets are components for high-speed digital and RF electronics for defense and commercial communications.

This innovation consists of a set of methodologies for preparing large area (>1 cm2) domains of single-atomic-layer graphite, also called graphene, in single (two-dimensional) crystal form. To fabricate a single graphene layer using chemical vapor deposition (CVD), the process begins with an atomically flat surface of an appropriate substrate and an appropriate precursor molecule containing carbon atoms attached to substituent atoms or groups. These molecules will be brought into contact with the substrate surface by being flowed over, or sprayed onto, the substrate, under CVD conditions of low pressure and elevated temperature. Upon contact with the surface, the precursor molecules will decompose. The substituent groups detach from the carbon atoms and form gas-phase species, leaving the unfunctionalized carbon atoms attached to the substrate surface. These carbon atoms will diffuse upon this surface and encounter and bond to other carbon atoms. If conditions are chosen carefully, the surface carbon atoms will arrange to form the lowest energy single-layer structure available, which is the graphene lattice that is sought.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Fabrication, Graphite, Nanotechnology
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