Manufacturing & Prototyping

Mercuric Iodide Anticoincidence Shield for Gamma-Ray Spectrometer

A film-growth process was developed for polycrystalline mercuric iodide that creates cost-effective, large-area detectors for high- energy charged-particle detection. A material, called a barrier film, is introduced onto the substrate before the normal mercuric iodide film growth process. The barrier film improves the quality of the normal film grown and enhances the adhesion between the film and the substrate.

Posted in: Briefs, Manufacturing & Prototyping, Spectroscopy, Spectroscopy, Materials properties

Improved Method of Design for Folding Inflatable Shells

Designs of gores reflect multiple considerations of assembly, stowage, and deployment.

An improved method of designing complexly shaped inflatable shells to be assembled from gores was conceived for original application to the inflatable outer shell of a developmental habitable spacecraft module having a cylindrical midlength section with toroidal end caps.

Posted in: Briefs, TSP, Manufacturing & Prototyping

High-Efficiency Artificial Photosynthesis Using a Novel Alkaline Membrane Cell

Successful artificial photosynthesis is significant for future human/robotic exploration and terrestrial carbon emissions control.

A new cell designed to mimic the photosynthetic processes of plants to convert carbon dioxide into carbonaceous products and oxygen at high efficiency, has an improved configuration using a polymer membrane electrolyte and an alkaline medium. This increases efficiency of the artificial photosynthetic process, achieves high conversion rates, permits the use of inexpensive catalysts, and widens the range of products generated by this type of process.

Posted in: Briefs, TSP, Manufacturing & Prototyping

Silicon Wafer-Scale Substrate for Microshutters and Detector Arrays

These substrates can be used in photomask generation and stepper equipment used to make ICs and MEMS devices.

The silicon substrate carrier was created so that a large-area array (in this case 62,000+ elements of a microshutter array) and a variety of discrete passive and active devices could be mounted on a single board, similar to a printed circuit board. However, the density and number of interconnects far exceeds the capabilities of printed circuit board technology. To overcome this hurdle, a method was developed to fabricate this carrier out of silicon and implement silicon integrated circuit (IC) technology. This method achieves a large number of high-density metal interconnects; a 100-percent yield over a 6-in. (≈15-cm) diameter wafer (one unit per wafer); a rigid, thermally compatible structure (all components and operating conditions) to cryogenic temperatures; re-workability and component replaceability, if required; and the ability to precisely cut large-area holes through the substrate.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Antennas, Architecture, Integrated circuits, Antennas, Architecture, Integrated circuits, Metals, Silicon alloys

Inert Welding/Brazing Gas Filters and Dryers

This system can be used in any process requiring reduction of inert-gas moisture level.

A system has been designed to reduce the hydrogen molecule content in inert gases that are used for shielding the welding arc and molten weld area during the manual fusion, automated welding, and induction brazing process. Two desiccant pipeline dryer cartridges are connected together using either aircraft or KC .250 fittings, and are installed in-line between the inert-gas facility source (argon and helium) and the welding machine. This process helps maintain alloy grain structure and integrity to engineering specifications during the welding and brazing processes. Also, this method enhances weldability when joining similar and dissimilar alloys. It is easy to restore the system to original drying capabilities by using a nitrogen purge or by oven drying. This design has low schedule impact or down time when being installed on machines or in systems. There is also a sight glass to indicate when servicing is needed.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Drying, Welding, Gases

Fabricating Copper Nanotubes by Electrodeposition

Relative to copper nanorods, copper nanotubes can be fabricated at lower cost.

Copper tubes having diameters between about 100 and about 200 nm have been fabricated by electrodeposition of copper into the pores of alumina nanopore membranes. Copper nanotubes are under consideration as alternatives to copper nanorods and nanowires for applications involving thermal and/or electrical contacts, wherein the greater specific areas of nanotubes could afford lower effective thermal and/or electrical resistivities. Heretofore, copper nanorods and nanowires have been fabricated by a combination of electrodeposition and a conventional expensive lithographic process. The present electrodeposition-based process for fabricating copper nanotubes costs less and enables production of copper nanotubes at greater rate.

Posted in: Briefs, Manufacturing & Prototyping, Fabrication, Productivity, Copper, Nanomaterials

Improved Fabrication of Ceramic Matrix Composite/Foam Core Integrated Structures

CMC face sheets bonded to ceramic foam cores are delamination-resistant and reduce cost, weight, and maintenance.

The use of hybridized carbon/silicon carbide (C/SiC) fabric to reinforce ceramic matrix composite face sheets and the integration of such face sheets with a foam core creates a sandwich structure capable of withstanding high-heat-flux environments (150 W/cm2) in which the core provides a temperature drop of 1,000 °C between the surface and the back face without cracking or delamination of the structure. The composite face sheet exhibits a bilinear response, which results from the SiC matrix not being cracked on fabrication. In addition, the structure exhibits damage tolerance under impact with projectiles, showing no penetration to the back face sheet. These attributes make the composite ideal for leading-edge structures and control surfaces in aerospace vehicles, as well as for acreage thermal protection systems and in high-temperature, lightweight stiffened structures.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Fabrication, Ceramics, Composite materials, Foams

Improved Blackbody Temperature Sensors for a Vacuum Furnace

Through proper selection of materials, it is possible to satisfy severe requirements.

Some improvements have been made in the design and fabrication of blackbody sensors (BBSs) used to measure the temperature of a heater core in a vacuum furnace. Each BBS consists of a ring of thermally conductive, high-melting-temperature material with two tantalum-sheathed thermocouples attached at diametrically opposite points. The name “blackbody sensor” reflects the basic principle of operation. Heat is transferred between the ring and the furnace heater core primarily by blackbody radiation, heat is conducted through the ring to the thermocouples, and the temperature of the ring (and, hence, the temperature of the heater core) is measured by use of the thermocouples.

Posted in: Briefs, Manufacturing & Prototyping, Measurements, Sensors and actuators, Sensors and actuators, Heat transfer, Heat transfer, Performance upgrades, Thermal testing

Thin-Film Solid Oxide Fuel Cells

Mass, volume, and the cost of materials can be reduced for a given power level.

The development of thin-film solid oxide fuel cells (TFSOFCs) and a method of fabricating them have progressed to the prototype stage. A TFSOFC consists of the following:

Posted in: Briefs, Manufacturing & Prototyping, Fuel cells, Product development, Fabrication

Novel Materials Containing Single-Wall Carbon Nanotubes Wrapped in Polymer Molecules

Coating carbon nanotubes in polymer molecules creates a new class of materials with enhanced mechanical properties for printed circuit boards, antenna arrays, and optoelectronics.

In this design, single-wall carbon nanotubes (SWNTs) have been coated in polymer molecules to create a new type of material that has low electrical conductivity, but still contains individual nanotubes, and small ropes of individual nanotubes, which are themselves good electrical conductors and serve as small conducting rods immersed in an electrically insulating matrix. The polymer is attached through weak chemical forces that are primarily non-covalent in nature, caused primarily through polarization rather than the sharing of valence electrons. Therefore, the electronic structure of the SWNT involved is substantially the same as that of free, individual (and small ropes of) SWNT. Their high conductivity makes the individual nanotubes extremely electrically polarizable, and materials containing these individual, highly polarizable molecules exhibit novel electrical properties including a high dielectric constant.

Posted in: Briefs, Manufacturing & Prototyping

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