Materials

Self-Healing Nanocomposites for Reusable Composite Cryotanks

Applications for COPVs include storage of natural gas and liquid hydrogen fuel in vehicles, and marine transport of propane via tanker ships. Composite cryotanks, or composite overwrapped pressure vessels (COPVs), offer advantages over currently used aluminum- lithium cryotanks, particularly with respect to weight savings. Future NASA missions are expected to use COPVs in spaceflight propellant tanks to store fuels, oxidizers, and other liquids for launch and space exploration vehicles. However, reliability, reparability, and reusability of the COPVs are still being addressed, especially in cryogenic temperature applications; this has limited the adoption of COPVs in reusable vehicle designs.

Posted in: Materials, Briefs

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Ceramic Adhesive and Methods for On-Orbit Repair of Re-Entry Vehicles

Material can be applied in space to repair damage that requires heat/oxidation protection upon re-entry to Earth’s atmosphere. This adhesive is capable of repairing damaged leading edge components of re-entry vehicles while in space, and is novel with regard to its ability to be applied in the vacuum of space, and in a microgravity environment. Once applied, the adhesive provides thermal and oxidation protection to the substrate (in this case, reinforced carbon/carbon composites, RCCs) during re-entry of a space vehicle. Although there may be many formulations for repair adhesives, at the time of this reporting, this is the first known adhesive capable of an onorbit repair.

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Lubricant Selection: What Every Design Engineer Needs to Know

Simply stated, lubrication refers to the age-old science of friction reduction. People have been using lubricants for thousands of years, experimenting with waxes and oils from vegetables, fish, and animals to move heavy materials with equipment designed to gain mechanical advantage. In more recent years, the discovery of petroleum oil in the 1800s ushered in a new era of lubrication developments as people learned how to refine this oil and use it for a variety of purposes. Machinery could now be developed to operate faster and under heavier loads by using lubricants to create a barrier that eliminates friction and metalon- metal contact.

Posted in: Materials, Mechanical Components, Machinery & Automation, White Papers

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Regenerable Sorbent for CO2 Removal

A durable, high-capacity regenerable sorbent can remove CO2 from the breathing loop under a Martian atmosphere. The system design allows nearambient temperature operation, needs only a small temperature swing, and sorbent regeneration takes place at or above 8 torr, eliminating the potential for Martian atmosphere to leak into the regeneration bed and into the breathing loop. The physical adsorbent can be used in a metabolic, heat-driven TSA system to remove CO2 from the breathing loop of the astronaut and reject it to the Martian atmosphere. Two (or more) alternating sorbent beds continuously scrub and reject CO2 from the spacesuit ventilation loop. The sorbent beds are cycled, alternately absorbing CO2 from the vent loop and rejecting the adsorbed material into the environment at a high CO2 partial pressure (above 8 torr). The system does not need to run the adsorber at cryogenic temperatures, and uses a much smaller temperature swing.

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Li-Ion Electrolytes With Improved Safety and Tolerance to High-Voltage Systems

Promising electrolytes are identified. Given that lithium-ion (Li-ion) technology is the most viable rechargeable energy storage device for near-term applications, effort has been devoted to improving the safety characteristics of this system. Therefore, extensive effort has been devoted to developing non-flammable electrolytes to reduce the flammability of the cells/battery. A number of promising electrolytes have been developed incorporating flame-retardant additives, and have been shown to have good performance in a number of systems. However, these electrolyte formulations did not perform well when utilizing carbonaceous anodes with the high-voltage materials. Thus, further development was required to improve the compatibility.

Posted in: Materials, Briefs, TSP

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Composite Aerogel Multifoil Protective Shielding

These composites are also suitable for environments containing an atmosphere. New technologies are needed to survive the temperatures, radiation, and hypervelocity particles that exploration spacecraft encounter. Multilayer insulations (MLIs) have been used on many spacecraft as thermal insulation. Other materials and composites have been used as micrometeorite shielding or radiation shielding. However, no material composite has been developed and employed as a combined thermal insulation, micrometeorite, and radiation shielding.

Posted in: Materials, Briefs, TSP

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Polymer-Reinforced, Non-Brittle, Lightweight Cryogenic Insulation

The primary application for cryogenic insulating foams will be fuel tank applications for fueling systems. It is crucial for this insulation to be incorporated into systems that survive vacuum and terrestrial environments. It is hypothesized that by forming an open-cell silica-reinforced polymer structure, the foam structures will exhibit the necessary strength to maintain shape. This will, in turn, maintain the insulating capabilities of the foam insulation. Besides mechanical stability in the form of crush resistance, it is important for these insulating materials to exhibit water penetration resistance. Hydrocarbon-terminated foam surfaces were implemented to impart hydrophobic functionality that apparently limits moisture penetration through the foam. During the freezing process, water accumulates on the surfaces of the foams. However, when hydrocarbon-terminated surfaces are present, water apparently beads and forms crystals, leading to less apparent accumulation.

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