Manufacturing & Prototyping

Making a Metal-Lined Composite-Overwrapped Pressure Vessel

The metal liner reduces loss of gas by diffusion without adding much weight.

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High-Temperature, High-Load-Capacity Radial Magnetic Bearing

Speed and temperature limits of rollingelement bearings can be exceeded.

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Fabrication of Spherical Reflectors in Outer Space

Process takes advantage of vacuum.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Progress in Fabrication of Rocket Combustion Chambers by VPS

Several documents in a collection describe aspects of the development of advanced materials and fabrication processes intended to enable the manufacture of advanced rocket combustion chambers and nozzles at relatively low cost. One concept discussed in most of the documents is the fabrication of combustion-chamber liners by vacuum plasma spraying (VPS) of an alloy of 88Cu/8Cr/4Nb (numbers indicate atomic percentages)—a concept that was reported in "Improved Alloy for Fabrication of Combustion Chambers by VPS" (MFS-26546), NASA Tech Briefs, Vol. 23, No.1 (January 1999), page 50. Another concept is the deposition of graded-composition wall and liner structures by VPS in order to make liners integral parts of wall structures and to make oxidation-and thermal- protection layers integral parts of liners: The VPS process is started at 100 percent of a first alloy, then the proportion of a second alloy is increased gradually from zero as deposition continues, ending at 100 percent of the second alloy. Yet another concept discussed in one of the documents is the VPS of oxidation-protection coats in the forms of nickel-and-chromium-containing refractory alloys on VPS-deposited 88Cu/8Cr/4Nb liners.

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Controlling Force and Depth in Friction Stir Welding

The proportionality between penetration force and penetration depth is exploited. Feedback control of the penetration force applied to a pin tool in friction stir welding has been found to be a robust and reliable means for controlling the depth of penetration of the tool. This discovery has made it possible to simplify depth control and to weld with greater repeatability, even on workpieces with long weld joints.

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Two Heat-Transfer Improvements for Gas Liquefiers

Medical oxygen liquefiers could operate more efficiently. Two improvements in heat-transfer design have been investigated with a view toward increasing the efficiency of refrigerators used to liquefy gases. The improvements could contribute to the development of relatively inexpensive, portable oxygen liquefiers for medical use.

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Modifications of Fabrication of Vibratory Microgyroscopes

The goal is to increase production yields. A micromachining process for the fabrication of vibratory microgyroscopes from silicon wafers, and aspects of the microgyroscope design that are inextricably linked with the fabrication process, have been modified in an effort to increase production yields from perspectives of both quantity and quality. Prior to the modifications, the effective production yield of working microgyroscopes was limited to one or less per wafer. The modifications are part of a continuing effort to improve the design and increase production yields to more than 30 working microgyroscopes per wafer.

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