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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Portable spectrometer using photosensitive readouts, monitors the amount of oxygen and hydrogen in the inert gas shield of a tungsten-inert gas welding process. A fiber optic bundle transmits the light from the welding arc to the spectrometer.
Portable spectrometer for monitoring oxygen and hydrogen as free gas or as dissociation products in inert gas shield of gas tungsten arc welding process
Cathodic cleaning processes with plasma arc, preparing aluminum surfaces for arc welding
Weldable aluminum alloys for aerospace systems, discussing composition and mechanical properties, strengthening, heat treatment and arc welding
Metal spinning forms combustion chamber sections and nozzle sections, arc welding joints sections to form rocket motor. Hastelloy-X as filler results in slightly weaker weld than the TD nickel weld, but permits formation of larger rocket motor than is otherwise possible.
Portable direct reading spectrometer for monitoring oxygen-hydrogen containing contaminants in gas tungsten arc welding process
A technical review of high reliability electrical terminations for electronic equipment was made. Seven techniques were selected from this review for further investigation, experimental work, and preliminary testing. From the preliminary test results, four techniques were selected for final testing and evaluation. These four were: (1) induction soldering, (2) wire wrap, (3) percussive arc welding, and (4) resistance welding. Of these four, induction soldering was selected as the best technique in terms of minimizing operator errors, controlling temperature and time, minimizing joint contamination, and ultimately producing a reliable, uniform, and reusable electrical termination.
Results of the effort of designing, fabricating, and testing of a 40 joules/lb (88.2 joules/Kg) high voltage energy storage capacitor suitable for operating a pulsed plasma thruster in a vacuum environment for millions of pulses are presented. Using vacuum brazing and heli-arc welding techniques followed by vacuum and high pressure helium leak tests it was possible to produce a hermetically sealed relatively light weight enclosure for the dielectric system. An energy density of 40 joules/lb was realized with a KF-polyvinylidene fluoride dielectric system. One capacitor was D.C. life tested at 4 KV (107.8 joules/lb) for 2,000 hours before it failed. Another exceeded 2,670 hours without failure at 38.3 joules/lb. Pulse life testing in a vacuum exceeded 300,000 discharges with testing still in progress. The D.C. life test data shows a small decrease in capacitance and an increase in dissipation factor with time. Heat transfer from the load to the capacitor must also be considered besides the self-heat generated by the capacitor.
Coating of mixed ceramics protects tungsten from oxidation. Originally suggested for critical tungsten components on Space Shuttle, mixture consists of 98.5 percent aluminum oxide and 1.5 percent silicon dioxide. It is particularly useful in welding when there is danger that welding arc can burn adjacent components. If coating is applied to nearby tungsten parts, it prevents arcing.
Two superalloys used extensively in the Space Shuttle main engine are Incoloy 903 and Inconel 718. The fatigue behavior of the two alloys under varying conditions is considered. Three heats of Incoloy 903 and two of Inconel 718 were used in the study. Material was tested in several conditions, including mill polish, longitudinal mill polish, transverse mill polish, chemically milled, chemically milled plus shotpeened on one side and on both sides, gas tungsten arc welded, and electron beam welded. Both round and flat tensile specimens were tested in universal test machines. It was found that surface condition influences test results. Transverse scratches resulting from polishing and rougher surfaces lower the stress at runout in relation to that obtained on longitudinally polished and/or smooth-surfaced specimens.
Practical application of plasma chemistry to the development of inorganic materials using both low temperature and warm plasmas are summarized. Topics cover: the surface nitrification and oxidation of metals; chemical vapor deposition; formation of minute oxide particles; the composition of oxides from chloride vapor; the composition of carbides and nitrides; freezing high temperature phases by plasma arc welding and plasma jet; use of plasma in the development of a substitute for petroleum; the production of silicon for use in solar cell batteries; and insulating the inner surface of nuclear fusion reactor walls.
The development of the common modules for the planned dual-keel Space Station, which is a figure-eight configuration that requires the use of four common modules linked by six docking nodes in the center of the Station, is examined. The fabrication of the proposed common module designs, which are a four-barrel common module structure built using excess external tank barrel panels (Martin Marietta Michoud Aerospace), and a three-barrel design consisting of 2219 Al skins with a waffle-grid pattern machined on the outer surface (Boeing Aerospace Corporation) is described. The assistance provided by the NASA-Marshall Space Flight Center's Materials and Processes Laboratory, in particular the variable polarity plasma arc welding process, in the development of the common modules is discussed.
Technique for making four-port, single-mode fiber-optic waveguide couplers requires no critically-precise fabrication operations or open-loop processes. Waveguide couplers analogous to beam-splitter prisms. Essential in many applications that require coherent separation or combination of two waves; for example, for interferometric purposes. Components of optical waveguide coupler held by paraffin on microscope slide while remaining cladding of two optical fibers fused together by arc welding.
Information is given in viewgraph form on space research and technology strategy, space shuttle experiments, experiments' planning, industry/university experiments, plasma arc welding in space, and international in-space experiments.
A simple and efficient image processing system is described which can provide one-dimensional image processing for sample rates approaching video rates. The system is utilized for visual feedback where guidance and process controls are required, such as for arc-welding robots.
An account is given of the efforts made to implement an off-line programming (OLP) system for a gas tungsten arc welding robot in actual manufacturing operations, namely those involved in the manufacture of the SSMEs. In conjunction with a real-time sensor control system, the OLP constitutes the Advanced Robotic Welding System, or 'AROWS'. OLP's task is to develop a robot-motion path without the initial use of the robot to 'teach' the characteristics of such motion; actual process parameters are recorded by OLP and correlated with the position along the weld.
Hard vacuum-deposited film improves nozzle properties. Tip and bore surfaces of proposed nozzle for feeding wire for gas/tungsten arc welding coated with film of synthetic diamond. Film gives nozzle following advantages: lower friction, thermal conductivity, less wear, electrical isolation of wire from nozzle, and high resistance to corrosion.
Theoretical and experimental studies of heat-tranfer in a space environment are discussed in reviews and reports. Topics addressed include a small-scale two-phase thermosiphon to cool high-power electronics, a low-pressure-drop heat exchanger with integral heat pipe, an analysis of the thermal performance of heat-pipe radiators, measurements of temperature and concentration fields in a rectangular heat pipe, and a simplified aerothermal heating method for axisymmetric blunt bodies. Consideration is given to entropy production in a shock wave, bubble-slug transition in a two-phase liquid-gas flow under microgravity, plasma arc welding under normal and zero gravity, the Microgravity Thaw Experiment, the flow of a thin film on stationary and rotating disks, an advanced ceramic fabric body-mounted radiator for Space Station Freedom phase 0 design, and lunar radiators with specular reflectors.