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Advanced Composite Thrust Chambers for In-Space Propulsion

Marshall Space Flight Center, Alabama Radiation-cooled, bipropellant thrust chambers are being used for in-space propulsion. To increase the performance of radiation-cooled engines, improved chamber materials are needed that will allow higher operating conditions (pressure and temperature), better resistance to oxidation, and reduced mass. During this effort, an innovative composite thrust chamber is being developed that will incorporate advanced hafnium oxide and iridium liner techniques as well as replacing the expensive, high-density rhenium with a low-mass carbon-carbon (C–C) structural wall.

Posted in: Manufacturing & Prototyping, Briefs

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Integrally Woven Fiber Architecture for Composite Turbine Blades

John H. Glenn Research Center, Cleveland, Ohio Composite turbine blades are currently fabricated by laying up multiple layers of fibers in the form of either unidirectional prepregs or thin woven cloth. Composites formed in this manner have poor through-thickness strength. It is also difficult, if not impossible, to form trailing edges as thin as necessary for optimum engine performance.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Assembly and Packaging to Mass-Produce Carbon Nanotube Vacuum Microdevices and Circuits

An assembly process allows mixing and matching of different types of electrode and dielectric layers assembled in a stack to create multi-electrode vacuum devices. NASA’s Jet Propulsion Laboratory, Pasadena, California Field-emission electron sources using carbon nanotubes (CNTs) are being targeted for low-power vacuum microelectronic applications for harsh-environment operation (high temperature, pressure, and corrosive atmosphere). While CNTs have demonstrated excellent properties in terms of low threshold field, low-power operation, and high-current densities, one of the problems that has persisted for vacuum electronic applications is the low yield of multi-electrode vacuum devices such as diodes, triodes, tetrodes, pentodes, etc.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Full-Cell Evaluation/Screening Technique for New Battery Chemistries

A full-cell configuration with a limited electrolyte in the cell is used to reflect the actual cell build conditions. John H. Glenn Research Center, Cleveland, Ohio A quick and cost-effective evaluation/screening technique for new battery chemistries was developed that integrates the individual advanced cell component in a full-cell format to identify the critical issues, such as cell component interaction and compatibility before proceeding to commercial production. To make the assessment more practical, a unique way of introducing limited electrolyte was developed. This technique enabled fast and low-cost screening to address any potential issues.

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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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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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