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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: Manufacturing & Prototyping, Briefs, TSP

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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: Manufacturing & Prototyping, Briefs, TSP

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High-Velocity, Pulsed Wire Arc Spray

Higher spray velocity should result in superior deposits. A high-velocity, pulsed wire arc spraying apparatus has been proposed and partly developed in an effort to improve the quality of coatings deposited by thermal spray techniques. In this apparatus, material from a wire arc is atomized and propelled toward a deposition substrate by a repetitively pulsed plasma jet. As explained below, this development is prompted by (1) the observation that the particle velocities attainable in traditional wire arc spraying are too low to enable the deposition of dense, high-quality coating materials that are often desired and (2) the expectation that higher spray velocities should result in superior coatings.

Posted in: Manufacturing & Prototyping, Briefs

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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: Manufacturing & Prototyping, Briefs

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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: Manufacturing & Prototyping, Briefs, TSP

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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: Manufacturing & Prototyping, Briefs, TSP

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Electron-Beam Welding of Superalloys at High Temperatures

Strain age cracks can be prevented. Electron-beam welding at high temperatures has been found to be a suitable process for joining structural components made by casting certain superalloys. This process can be used in the fabrication of superalloy parts that must withstand high operating temperatures. Examples of such parts include exhaust ducts of advanced aerospace engines and end caps on turbine buckets.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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