Manufacturing & Prototyping

In-Situ Mixing, Degassing, Decavitation, and Extrusion Modules for Fused Deposition Modeling 3D Printers

A resonant acoustics mixing mechanism equipped with high-vacuum pulling capacity will be employed. John H. Glenn Research Center, Cleveland, Ohio Additively manufactured 3D articles of certain high-temperature polymer composites such as ULTEM 1000 reinforced with chopped carbon fibers and printed by current state-of-the-art Fused Deposition Modeling (FDM) printers, suffer significantly with high porosity due to moisture-induced cavitation during the liquefying process under high printing temperatures because the pre-fabricated feedstock filaments contain excessive moisture trapped in polymer matrix or fiber interfaces that is extremely difficult to remove. During compounding (mixing of chopped fibers with resin) and the filament extrusion process, controlling moisture absorption is extremely difficult and very costly. Furthermore, compounding and filament fabrication are two separate processes normally performed at different plants, and thus add extra costs and technical challenge of keeping the material dry. In the case of the high-temperature polymer, it is even more difficult to control the residual moisture content and is more prone to blistering during FDM printing due to higher melting temperature.

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Stable, Flat Packaging Concepts for Large Detector Arrays

Applications include packing of back-illuminated and delta-doped arrays without damage to sensitive surfaces. NASA’s Jet Propulsion Laboratory, Pasadena, California A ceramic vacuum chuck is used to hold large detector arrays flat while being attached parallel to a rigid substrate. Once held in the vacuum chuck, the component is typically seized by epoxy against a rigid substrate. The problem that interferes with this operation happens when the epoxy spreads to places where it is not wanted, even into the gap between the component and its vacuum chuck, and over electrical contacts that are intended for wire bonding.

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Dual-Polarized W-Band Metal Patch Antenna Element for Phased Array Applications

Interlaced transmit/receive all-metal patch elements eliminate the need for discrete isolators and increase efficiency. NASA’s Jet Propulsion Laboratory, Pasadena, California W-band active phased array antennas have a very small inter-element pitch (≈2 mm). In this innovation, instead of trying to integrate isolators into the unit cell to separate transmit and receive signals, an interlaced triangular grid of metal patch elements has been developed. The isolation between transmit elements and receive elements has been demonstrated to be on the order of 25 dB or more, precluding the need for discrete isolator circuits. Using metal patch technology, the element and associated interconnect loss has been demonstrated to be 0.5 dB at 94 GHz, which represents an efficiency of 89%.

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High-Temperature Superconducting Bolometric Devices on Amorphous Silicon Nitride Membranes

Applications include defense-related infrared launch detection and night vision. NASA’s Jet Propulsion Laboratory, Pasadena, California There has been a great deal of interest in building bolometers from hightemperature superconductors due to their high transition temperatures and the associated ease of cooling. High-temperature superconducting (high Tc) bolometers are difficult to fabricate because the standard method of thermal isolation is not compatible with these materials. A method is described that allows a standard thermal isolation technique (using amorphous silicon nitride membranes) to be used with high-temperature superconductors.

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Uniformly Etched Lateral Gratings Applied to Pre-existing Ridge Waveguides

New technology is 100 times smaller and has fewer components with possibly the same performance. NASA’s Jet Propulsion Laboratory, Pasadena, California There is great difficulty in implementing lateral gratings in GaSb-based lasers. Commercially, single-frequency GaSb lasers have been fabricated using metal gratings deposited laterally to the ridge-waveguide (RWG) stripe. The disadvantage of this is that the laser performance is compromised by additional optical loss due to radiation absorption by the metal. Fabricating lasers in this way limits the potential for high-power performance. A better method is to etch gratings into the semiconductor, but generally, patterning these grating structures is difficult because of nonuniformity of the grating pattern and etching difficulty due to sub-micrometer dimensions.

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High-Precision Thin Film Metal Liftoff Technique

This process can be used by industries that need to fabricate microelectronic devices and superconducting sensors. Goddard Space Flight Center, Greenbelt, Maryland The objective of this work was to develop a thin film metal liftoff process that would allow one to accurately pattern two-micron-wide (or wider) features. The goal of this innovation was to pattern thin metal films on silicon substrates. The thin metal films can be deposited using physical vapor deposition techniques. The metallic films to be lifted off were deposited via DC magnetron sputtering, in which the mean free path of the metal atoms to be deposited is on the order of one micron. Thus, the deposited metal could conformally coat structures to fill in gaps that were greater than approximately one micron tall.

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Process for 3D Printer Filament Fabrication

Marshall Space Flight Center, Alabama Conventional filament extrusion processes are unsuitable for recycling materials on the International Space Station due to requirements for continuous monitoring and tuning, as well as poor filament dimensional control. The Positrusion process recycles scrap or waste thermoplastics into filament for 3D fused filament fabrication (FFF) printers.

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