Manufacturing & Prototyping

Durable Joining Technology for Uniformly-Curved Composite Sandwich Structures

An insert improves distribution of load through the joint, increasing safety.

NASA’s next-generation launch vehicles will be enabled by high-performance composite materials and innovative manufacturing methods. As such, NASA uses adhesively bonded joints where possible instead of mechanically fastened (bolted) joints to design and manufacture structures. The adhesive joints typically are lighter and distribute loads more efficiently across an interface, while mechanically fastened joints are prone to stress concentrations around the bolts.

Posted in: Briefs, Manufacturing & Prototyping, Joining, Adhesives and sealants, Composite materials, Launch vehicles

Ohmic Contact to N- and P-Type Silicon Carbide

Ohmic contact can be formed in one process step.

Electrical ohmic contacts can be simultaneously formed on silicon carbide (SiC) semiconductors having donor and acceptor impurities (n- and p-type doping, respectively). This implies that such contacts can be formed on SiC layers in one process step during the fabrication of the semiconductor device. This also means that the multiple process steps for fabricating contacts onto n- and p-type surfaces, which is characteristic of the prior art, will be greatly reduced, thereby reducing time and cost, and increasing yield (more process steps and complexity increases chances for lower yields). Another significance of this invention is that this scheme can serve as a non-discriminatory, universal ohmic contact to both n- and p-type SiC, without compromising the reliability of the specific contact resistivity when operated at temperatures in excess of 600 °C.

Posted in: Briefs, Manufacturing & Prototyping, Semiconductor devices, Semiconductor devices, Product development, Fabrication

Flap Edge Noise Reduction Fins

This innovation has applications in aircraft leading edge slats and rotor tips for propulsion components on both aircraft and rotorcraft, as well as on wind turbines.

Aircraft noise is a significant problem with both economic and public health implications, especially for communities near airports. As a result, increasingly stringent constraints are being placed on aircraft carriers worldwide to reduce this noise. The current disclosure focuses on airframe noise generated at or near the surface of the flap-side edge.

Posted in: Briefs, Manufacturing & Prototyping, Airframes, Wings, Noise, Noise

Advanced Composite Thrust Chambers for In-Space Propulsion

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: Briefs, Manufacturing & Prototyping, Composite materials, Spacecraft

Integrally Woven Fiber Architecture for Composite Turbine Blades

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: Briefs, TSP, Manufacturing & Prototyping, Composite materials, Fibers, Gas turbines

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.

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: Briefs, TSP, Manufacturing & Prototyping, Assembling, Packaging, Nanomaterials

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.

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.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Battery cell chemistry, Battery cell chemistry, Fuel cells

Growth Method for Chalcongenide Phase-Change Nanostructures

Nanometer-scale materials can provide smaller devices than those currently available.

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.

Posted in: Briefs, Manufacturing & Prototyping, Nanomaterials

ELID Grinding of Large Aspheres

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.

Posted in: Briefs, Manufacturing & Prototyping, Manufacturing equipment and machinery, Manufacturing processes, Ceramics

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.

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.

Posted in: Briefs, Manufacturing & Prototyping, Fuel cells, Fibers, Polymers, Textiles

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