Home

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.

Posted in: Materials, Briefs, TSP

Read More >>

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

Read More >>

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

Read More >>

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, TSP

Read More >>

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, TSP

Read More >>

100 Percent Solids: Superior Adhesive Technology for the Medical Industry

Adhesives using 100 percent solids coating act fast, without need for solvents. In the medical industry, adhesives play a crucial role in applications ranging from diagnostics and device assembly to transdermal and wound care. There are varying methods by which an adhesive can be coated onto a substrate, but solvent coating has dominated in the medical industry for many years. Solvent-coated silicone, acrylic, and rubber-based adhesives are widely used as medical adhesive solutions. Despite their popularity, solvent-coated adhesives are far from a perfect answer to the medical market’s needs. Solvents may contain volatile organic compounds (VOCs) and even carcinogens that can be dangerous to humans. There are also major concerns regarding outgassing or leaching from solvent- coated adhesives in medical settings. As a process, solvent coating is not especially efficient with adhesives requiring drying, which can limit speed and cost-effectiveness of processing.

Posted in: Bio-Medical, Manufacturing & Prototyping, Materials / Adhesives / Coatings, Materials, Coatings & Adhesives, Medical, Briefs, MDB

Read More >>

Cu-Cr-Nb-Zr Alloy for Rocket Engines and Other High-Heat- Flux Applications

Applications include high-temperature, highefficiency industrial heat exchangers, welding electrodes, and head gaskets for automobile racing engines. Rocket-engine main combustion chamber liners are used to contain the burning of fuel and oxidizer and provide a stream of high-velocity gas for propulsion. The liners in engines such as the Space Shuttle Main Engine are regeneratively cooled by flowing fuel, e.g., cryogenic hydrogen, through cooling channels in the back side of the liner. The heat gained by the liner from the flame and compression of the gas in the throat section is transferred to the fuel by the liner. As a result, the liner must either have a very high thermal conductivity or a very high operating temperature.

Posted in: Materials, Briefs, TSP

Read More >>