Manufacturing & Prototyping

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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3D Microwave Print Head System for Melting Materials

This approach has applications in industry where solid materials need to be melted. NASA’s Jet Propulsion Laboratory, Pasadena, California There is a need to develop an efficient method for processing lunar regolith in support of future missions to colonize the Moon. A system for heating lunar regolith (“moon soil”) using microwaves for processing has been developed. It relies on an enhanced heating effect based on a large temperature gradient forming when a sample of lunar regolith under microwave radiation emits heat from its surface rapidly as the core is melting. Once the core melts, the sample absorbs microwave energy more readily. This molten lunar regolith would then exit the sample tube, and the lunar regolith could then be introduced into molds for forming a desired structure or building block.

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Novel Chemistry for Deposition of MgF2 Thin Films

NASA’s Jet Propulsion Laboratory, Pasadena, California Magnesium fluoride (MgF2) thin films are useful for many different optics applications. In particular, they are useful for ultraviolet anti-reflective and protective coatings. However, in the far UV, one needs a very small, controllable amount of material to get the best optical performance. That is difficult to achieve with conventional methods. Atomic layer deposition (ALD) is an ideal UV-compatible thin-film deposition technique due to its ability to deposit uniform, pin-hole free films with angstrom-level thickness control. Therefore, it is an ideal technique to use to deposit protective thin films in the 2-nm thickness range. However, conventional ALD-MgF2 reactions are very unpredictable due to the low reactivity and volatility of the precursors.

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Self-Aligning Lug for Adapting Carbon Fiber Rods to a Bolted Metallic Connection

Joint strength is controlled through precise bond line control. Ames Research Center, Moffett Field, California The enormous strength of unidirectional carbon fiber composite rods is difficult to take advantage of at their ends because of inadequate joining technology. Bolting does not work with unidirectional composites, and bonding is difficult due to stiffness mismatches between the metallic and composite connections. Ideally, a thick bond is desired so that the relatively softer adhesive can shear and distribute shear stresses instead of peaking at the ends of the bond. Thick bonds are difficult to obtain and repeatedly control with conventional methods of beads, bonding wire, shim, or tooling. Most of these methods control the minimum thickness of the bond, but do not control the maximum thickness. In addition, traditional joint types such as lap, strap, and scarf are not ideal for this application.

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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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Integrated PEMFC Flow Field Design for Gravity-Independent Passive Water Removal

The design solves safety as well as reliability issues. A gravity-independent PEM (proton exchange membrane) fuel cell stack has been developed that will operate at high-pressure H2 and O2 conditions with the requirement for relatively modest H2 and O2 gas circulation. Until now, in order to get higher efficiency, excess reactant gas flow was required to prevent water slug formation in gas channels, thus reducing fuel cell performance. In addition, this excess gas flow is typically supported by mechanical pumps and/or a high-pressure ejector system. All of these in a closed space environment contributed to potential safety as well as reliability issues due to the potential failure of mechanical pumps and ejectors.

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