Materials

Ambient Dried Aerogels

A method has been developed for creating aerogel using normal pressure and ambient temperatures. All spacecraft, satellites, and landers require the use of thermal insulation due to the extreme environments encountered in space and on extraterrestrial bodies. Ambient dried aerogels introduce the possibility of using aerogel as thermal insulation in a wide variety of instances where supercritically dried aerogels cannot be used. More specifically, thermoelectric devices can use ambient dried aerogel, where the advantages are in situ production using the cast-in ability of an aerogel.

Posted in: Materials, Briefs

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Passivation of Flexible YBCO Superconducting Current Lead With Amorphous SiO2 Layer

The aim of this project is to design and construct leads from YBCO composite conductors to reduce the heat load to adiabatic demagnetization refrigerators. Adiabatic demagnetization refrigerators (ADR) are operated in space to cool detectors of cosmic radiation to a few 10s of mK. A key element of the ADR is a superconducting magnet operating at about 0.3 K that is continually energized and de-energized in synchronism with a thermal switch, such that a piece of paramagnetic salt is alternately warm in a high magnetic field and cold in zero magnetic field. This causes the salt pill or refrigerant to cool, and it is able to suck heat from an object, e.g., the sensor, to be cooled. Current has to be fed into and out of the magnets from a dissipative power supply at the ambient temperature of the spacecraft. The current leads that link the magnets to the power supply inevitably conduct a significant amount of heat into the colder regions of the supporting cryostat, resulting in the need for larger, heavier, and more powerful supporting refrigerators. The aim of this project was to design and construct high-temperature superconductor (HTS) leads from YBCO (yttrium barium copper oxide) composite conductors to reduce the heat load significantly in the temperature regime below the critical temperature of YBCO.

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Reliability Testing of GORE® Protective Vents in Telecommunication Enclosures

Premature failure of telecommunication equipment leads to network downtime, higher costs, increased maintenance and decreased brand loyalty. One of the most significant challenges for this equipment is withstanding the conditions of the environment in which it is installed.

Posted in: Materials, White Papers

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Sterilization of Bioresorbable Polymers

Sterilization method should be considered during the design phase. Bioresorbable polymers for medical devices encompass a broad class of materials with two of the more common materials being poly(L-lactic acid) and poly(lactic-co-glycolic acid). Some terminal sterilization processes may result in changes in materials properties, thereby significantly impacting the functional behavior of bioresorbable implants. Matching a terminal sterilization method to a bioresorbable implant requires the materials properties of the device to be considered as part of the product development process. Currently, there are several types of terminal sterilization processes in use for these polymers, including gamma radiation, e-beam radiation, and ethylene oxide (EtO). Steri lization with nitrogen dioxide (NO2) gas provides a room-temperature alternative that should be considered for this class of materials.

Posted in: Bio-Medical, Custom & Contract Manufacturing, Monitoring & Testing, Packaging, Implants & Prosthetics, Materials / Adhesives / Coatings, Materials, Coatings & Adhesives, Composites, Plastics, Medical, Briefs, MDB

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Centrifugal Sieve for Gravity-Level-Independent Size Segregation of Granular Materials

Centrifugal force can significantly shorten the time to segregate feedstock into a set of different-sized fractions. Conventional size segregation or screening in batch mode, using stacked vibrated screens, is often a time-consuming process. Utilization of centrifugal force instead of gravity as the primary body force can significantly shorten the time to segregate feedstock into a set of different-sized fractions. Likewise, under reduced gravity or microgravity, a centrifugal sieve system would function as well as it does terrestrially. When vibratory and mechanical blade sieving screens designed for terrestrial conditions were tested under lunar gravity conditions, they did not function well. The centrifugal sieving design of this technology overcomes the issues that prevented sieves designed for terrestrial conditions from functioning under reduced gravity.

Posted in: Materials, Briefs

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Ion Exchange Technology Development in Support of the Urine Processor Assembly

Resins can filter gypsum out of urine, improving the water recovery rate. The urine processor assembly (UPA) on the International Space Station (ISS) recovers water from urine via a vacuum distillation process. The distillation occurs in a rotating distillation assembly (DA) where the urine is heated and subjected to sub-ambient pressure. As water is removed, the original organics, salts, and minerals in the urine become more concentrated and result in urine brine. Eventually, water removal will concentrate the urine brine to super saturation of individual constituents, and precipitation occurs. Under typical UPA DA operating conditions, calcium sulfate or gypsum is the first chemical to precipitate in substantial quantity. During preflight testing with ground urine, the UPA achieved 85% water recovery without precipitation.

Posted in: Materials, Briefs

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Nickel-Graphite Composite Compliant Interface and/or Hot Shoe Material

This innovation is a technique for joining various thermoelectric materials into segmented device architectures. Next-generation high-temperature thermoelectric-power-generating devices will employ segmented architectures and will have to reliably withstand thermally induced mechanical stresses produced during component fabrication, device assembly, and operation. Thermoelectric materials have typically poor mechanical strength, exhibit brittle behavior, and possess a wide range of coefficient of thermal expansion (CTE) values. As a result, the direct bonding at elevated temperatures of these materials to each other to produce segmented leg components is difficult, and often results in localized microcracking at interfaces and mechanical failure due to the stresses that arise from the CTE mismatch between the various materials. Even in the absence of full mechanical failure, degraded interfaces can lead to increased electrical and thermal resistances, which adversely impact conversion efficiency and power output.

Posted in: Materials, Briefs

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