Manufacturing & Prototyping

Growth Method for Chalcongenide Phase-Change Nanostructures

Nanometer-scale materials can provide smaller devices than those currently available. Ames Research Center, Moffett Field, California Recently, one-dimensional (1-D) nanostructures, such as nanowires and nanotubes, have become the focal point of research in nanotechnology due to their fascinating properties. These properties are intrinsically associated with low dimensionality and small diameters, which may lead to unique applications in various nanoscale devices. It is generally accepted that 1-D nanostructures provide an excellent test ground for understanding the dependence of physical, electrical, thermal, optical, and mechanical properties on material dimensionality and physical size. In particular, 1-D semiconductor nanostructures, which exhibit different properties as compared with their bulk or thin film counterparts, have shown great potential in future nanoelectronics applications in data storage, computing, and sensing devices.

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ELID Grinding of Large Aspheres

Goddard Space Flight Center, Greenbelt, Maryland This work focused on a manufacturing process to produce silicon carbide optical surfaces with low mid-spatial surface errors. Mid-spatial frequency (MSF) and high-spatial frequency (HSF) surface errors in the grinding of fast aspheres are amplified in hard ceramics like silicon carbide due to cyclic tool wear rates, vibration, and tool deformation.

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Highly Aligned Electrospun Fibers and Mats

These mats have applications in fuel and solar cells, smart textiles, and in wound dressings and tissue engineering scaffolds. Langley Research Center, Hampton, Virginia A modified electrospinning apparatus has been created for spinning highly aligned polymer fibers. Fiber placement, orientation, and porosity are difficult to control using conventional electrospinning apparatus. Conventional electrospinning creates randomly oriented fibers that are well suited to nonwoven mats, but not to other applications. This new technology will broaden the range of engineering applications of electrospun materials. The apparatus provides a simple and inexpensive means of producing fibers and mats of controlled fiber diameter, porosity, and thickness.

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Solar Panel and System Design to Reduce Heating and Optimize Corridors for Lower-Risk Planetary Aerobraking

New approach features aggressive load reduction to reduce risk. Goddard Space Flight Center, Greenbelt, Maryland This innovation presents a spacecraft aerobraking approach that reduces heating and optimizes corridors, which reduces overall risk. This is accomplished by combining solar panel aspect ratio and edge features with simple spacecraft packaging optimization and integrated thermal-analysis techniques that also allow specifying a more benign temperature corridor.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Low-Cost, Very Large Diamond-Turned Metal Mirror

Reliable plating and diamond-turning technologies produce visible quality mirrors for applications such as semiconductor manufacturing. Marshall Space Flight Center, Alabama This innovation is a method for fabricating a low-cost, lightweight, large-aperture mirror by constructing only the mirror substrate by electroforming on a master form machined from plastic foam. Electroformed tubes of the same NiP alloy are installed in the foam mirror substrate master. Installing electroformed NiP tubes in the plastic mirror master before plating on the plastic foam mirror substrate allows the mirror faceplate and the back surface of the mirror to be plated onto the ends of the connecting tubes in the foam plastic. Removal of the foam after plating is complete results in a very stiff and lightweight mirror substrate made only of a single material. The low cost of the electroformed mirror substrate is made possible by very fast production of a master surface made of plastic foam that can be rapidly machined with modern, high-speed machining technology to very good mechanical tolerances in only a few hours.

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Very-High-Load-Capacity Air Bearing Spindle for Large Diamond Turning Machines

Marshall Space Flight Center, Alabama Large-load-capacity oil hydrostatic bearings generate prohibitive amounts of heat in large sizes when run at speeds useful for diamond turning of optical components. The viscosity of air is more than three orders of magnitude less than the thinnest oil; therefore, the frictional heating of large-diameter air bearings is very small and very manageable. A formidable manufacturing problem with large air bearings is that the extremely low viscosity of air requires that the thickness of the bearing film is also very small. This very small bearing clearance of 5–8 micrometers means that the required accuracy of geometry and dimensions of air bearing components is extremely difficult to achieve.

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Tailored 3D Fiber Architecture to Improve CVI Processing

Marshall Space Flight Center, Huntsville, Alabama An improvement has been made to the infiltration of 3D woven and 3D braided preforms that will lead to the manufacture of CMC (ceramic matrix composite) and C–C (carbon-carbon) composites based on 3D fiber architectures that have low residual porosity and smaller void sizes. Tailoring the fiber architectures by the use of several combinations of larger and smaller warp, fill, and z yarns formed pathways into the thickness of the fabrics to improve fluid flow through the preform during CVI (chemical vapor infiltration) processing.

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