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Aluminum Rocket Engine Injector Fabricated Using 3D Additive Manufacturing

Marshall Space Flight Center, Alabama Liquid rocket engine injectors can be extremely expensive to manufacture and hard to iterate to achieve high performance. Internal sealing points can also be the source of reliability issues. The technology disclosed here covers the application of a 3D additive manufacturing (AM) process to produce a functional aluminum injector for liquid propellant rocket engines, along with injector and overall engine design features that optimize the application of such processes to improve performance, reliability, and affordability relative to components produced using standard machining processes and designs. Aluminum was used for the injector instead of higher- temperature metals like stainless steel because its thermal conductance properties provide more opportunity to leverage the cooling potential of liquid oxygen and other cryogenic propellants.

Posted in: Briefs

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Making Flexible Ablators that are Flexible Char Formers

Ames Research Center, Moffett Field, California An approach was developed for making low-density, flexible ablators for a thermal protection system (TPS) from a flexible fibrous carbon substrate and a polymer resin. The material is foldable and stowable, and can be deployed in space without compromising performance. In addition, the material can be stowed in space for very long periods of time (years) without compromising deployability or performance. These flexible ablators offer an alternative to rigid TPS materials, thereby reducing design complexity and cost. On charring, the flexible ablative TPS retains its flexibility. After charring, the TPS has comparable flexibility and mechanical properties to the virgin material.

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Method for Providing Semiconductors Having Self-Aligned Ion Implant

Refined self-aligned ion implantation for improved SiC high-temperature transistors. John H. Glenn Research Center, Cleveland, Ohio This is a modification to technology for realizing durable and stable electrical functionality of high-temperature transistors. This modification is believed crucial to experimental implementation of SiC junction field effect transistors that electrically operated continuously at 500 °C for over 10,000 hours in an air ambient with less than 10% change in operational transistor parameters.

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Femtosecond Laser Processing of Metal and Plastics

Precision machining can be achieved with no thermal affects and minimal post-processing. Amada Miyachi America, Monrovia, California and Jenoptik, Jena, Germany While precise and fast, the down side to cutting with microsecond (ms) fiber lasers has been that the parts require a number of post-processing operations after they are cut, which add significantly to part cost, and can also damage mechanically delicate parts.

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Regenerable Trace-Contaminant Sorbent for the Primary Life Support System (PLSS)

This technology has applications in air-revitalization systems on spacecraft, submarines, automobiles, and commercial aircraft. Lyndon B. Johnson Space Center, Houston, Texas The NASA objective of expanding the human experience into the far reaches of space requires the development of regenerable life support systems. This work addresses the development of a regenerable air-revitalization system for trace-contaminant (TC) removal for the spacesuit used in extravehicular activities (EVAs). Currently, a bed of granular activated carbon is used for TC control. The carbon is impregnated with phosphoric acid to enhance ammonia sorption, but this also makes regeneration difficult, if not impossible. Temperatures as high as 200 °C have been shown to be required for only partial desorption of ammonia on time scales of 18,140 hours. Neither these elevated temperatures nor the long time needed for sorbent regeneration are acceptable. Thus, the activated carbon has been treated as an expendable resource, and the sorbent bed has been oversized in order to last throughout the entire mission.

Posted in: Briefs, TSP

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Lithium Fluoride as a Polysulfide Shuttle Inhibitor for Lithium Sulfur Chemistry

This invention imparts properties such as reinforcement, enhanced tensile strength, and/or electrical and thermal conductivity to composites. Lyndon B. Johnson Space Center, Houston, Texas In a lithium sulfur cell, the reduction of sulfur to lithium sulfide is a critical series of reactions that provides a large theoretical capacity of 1,672 mAh/g sulfur. One of many challenges in this system is the solubility of generated lithium polysulfides during the charge/discharge process. These polysulfides derived from the reduction of elemental sulfur are soluble in organic electrolytes, and can be reduced at the anode, causing an undesired reaction. Polysulfide species can also accumulate at the surface of the cathode and be further reduced to lower-order polysulfides such as Li2S2 or Li2S. The insulating nature of these lower-order polysulfides blocks the electron pathway on the carbon cathode.

Posted in: Briefs, TSP

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Fibers of Aligned Single-Wall Carbon Nanotubes and Process for Making the Same

This invention imparts properties such as reinforcement, enhanced tensile strength, and/or electrical and thermal conductivity to composites. Lyndon B. Johnson Space Center, Houston, Texas Single-wall carbon nanotubes (SWNTs) are fullerenes of closed-cage carbon molecules typically arranged in hexagons and pentagons. Commonly known as “buckytubes,” these cylindrical carbon structures have extraordinary properties, including high electrical and thermal conductivity, as well as high strength and stiffness. With intrinsic strength estimated to be on the order of 100 times that of steel, SWNTs are a possible strengthening reinforcement in composite materials. The intrinsic electronic properties of SWNTs also make them electrical conductors and useful in applications involving field mission devices such as flat-panel displays, and in polymers used for radio frequency interference and electromagnetic shielding that require electrical conductance properties.

Posted in: Briefs

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