Manufacturing & Prototyping

Tool For Friction Stir Tack Welding of Aluminum Alloys

The same setup can be used for tack welding and full friction stir welding. A small friction-stir- welding tool has been developed for use in tack welding of aluminum-alloy workpieces. It is necessary to tack-weld the workpieces in order to hold them together during friction stir welding because (1) in operation, a full-size friction-stir-welding tool exerts a large force that tends to separate the workpieces and (2) clamping the workpieces is not sufficient to resist this force.

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Improving Plating by Use of Intense Acoustic Beams

This method affords enhanced capabilities for maskless plating and process control. An improved method of selective plating of metals and possibly other materials involves the use of directed high-intensity acoustic beams. The beams, typically in the ultrasonic frequency range, can be generated by fixed- focus transducers (see figure) or by phased arrays of transducers excited, variously, by continuous waves, tone bursts, or single pulses. The nonlinear effects produced by these beams are used to alter plating processes in ways that are advantageous.

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Fabricating Composite-Material Structures Containing SMA Ribbons

Repeatable, predictable structures can be fabricated. An improved method of designing and fabricating laminated composite-material (matrix/fiber) structures containing embedded shape-memory-alloy (SMA) actuators has been devised. Structures made by this method have repeatable, predictable properties, and fabrication processes can readily be automated.

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Pressure-Sensor Assembly Technique

An essential underfilling step can be performed without compromising a diaphragm. Nielsen Engineering & Research (NEAR) recently developed an ultrathin data acquisition system for use in turbomachinery testing at NASA Glenn Research Center. This system integrates a microelectro- mechanical-systems- (MEMS-) based absolute pressure sensor [0 to 50 psia (0 to 345 kPa)], temperature sensor, signal-conditioning application-specific integrated circuit (ASIC), microprocessor, and digital memory into a package which is roughly 2.8 in. (7.1 cm) long by 0.75 in. (1.9 cm) wide. Each of these components is flip-chip attached to a thin, flexible circuit board and subsequently ground and polished to achieve a total system thickness of 0.006 in. (0.15 mm). Because this instrument is so thin, it can be quickly adhered to any surface of interest where data can be collected without disrupting the flow being investigated.

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Wafer-Level Membrane-Transfer Process for Fabricating MEMS

This process is well suited for structures fabricated on dissimilar substrates. A process for transferring an entire wafer-level micromachined silicon structure for mating with and bonding to another such structure has been devised. This process is intended especially for use in wafer-level integration of microelectro- mechanical systems (MEMS) that have been fabricated on dissimilar substrates.

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A Reactive-Ion Etch for Patterning Piezoelectric Thin Film

Gaseous mixtures BCl3 and Cl2 are highly selective for etching PbZr1-xTixO3 films. Reactive-ion etching (RIE) under conditions described below has been found to be a suitable means for patterning piezoelectric thin films made from such materials as PbZr1-xTixO3 or BaxSr1-xTiO3. In the original application for which this particular RIE process was developed, PbZr1-xTixO3 films 0.5 μm thick are to be sandwiched between Pt electrode layers 0.1 µm thick and Ir electrode layers 0.1 μm thick to form piezoelectric capacitor structures. Such structures are typical of piezoelectric actuators in advanced microelectromechanical systems now under development or planned to be developed in the near future.

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In Situ Electrochemical Deposition of Microscopic Wires

Tedious, expensive post-growth assembly is no longer necessary.

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