Materials & Coatings

Hierarchical Support for Nanocatalysts

Lyndon B. Johnson Space Center, Houston, Texas

This work focused on enhancing catalyst activity and durability by developing a method to control size, dispersion, and exposure. Existing nanocatalysts are typically fabricated in bulk or powder form. There are monolithic catalysts, but they rely on meso-porous materials as supports. Bulk nanocatalysts suffer from a lack of complete exposure to reagents, counteracting the benefits of the nanoparticles. Catalysts upon meso-porous support have limited exposure due to diffusion distances through the porous support. This requires higher catalyst loading, and may lead to particle coalescence and deactivation.

Posted in: Briefs, Materials, Catalysts, Nanomaterials

Control of Carbon Nanotube Density and Tower Height in an Array

Applications include high-density semiconductor chips, and heat dissipation and thermal conduction in personal computers, smartphones, and televisions.

Ames Research Center, Moffett Field, California

Use of arrays of carbon nanotubes (CNTs) as an intermediary for transport of electrical particles (e.g., electrons) and/or transport of thermal energy from one body to another has grown. For example, a CNT array may be used for dissipation of thermal energy or accumulated electrical charge associated with operation of an electronics device or system. However, the device or system may require use of different CNT array densities in various regions because of differing transport requirements.

Posted in: Briefs, Materials, Electronic equipment, Electronic equipment, Nanotechnology, Semiconductors

In-Situ Chemical Analysis of Material Surfaces

Composition by freezing uses laser ablation and laser ionization mass spectrometry for detection of chemical, pharmaceutical, biotech, and hazardous materials.

NASA’s Jet Propulsion Laboratory, Pasadena, California

In order to understand whether the ablation laser would cause chemical reactions within the trapped organic molecules during resonant laser ablation of water ice containing organic molecules, a two-layer approach was devised. The first layer consisted of D2O ice containing organics that are inactive for the laser wavelength used (2.94 microns), and shown not to ablate under these conditions. When an additional layer of H2O ice was deposited on top of the D2O layer, both H2O and D2O layers, and the organics embedded in the D2O layer, became ablated due to resonant excitation of the H2O ice layer that transferred energy to the D2O layer. This showed that the organic matter is not damaged.

Posted in: Briefs, Materials, Lasers, Lasers, Water, Chemicals, Hazardous materials, Test equipment and instrumentation, Test procedures

New Material Increases Lifetime of Solar-Powered Electrons

Nobody wants a laptop computer that stops working when a cloud passes by. Storing sunlight as fuel that can be later used to drive fuel cells requires new materials. Scientists demonstrated just such a material by combining two oxides on the atomic scale.

Posted in: Articles, News, Energy, Energy Storage, Materials

Flexible, High-Temperature Polyimide/Urea Aerogels

Cross-linked polyimide/urea aerogels are potential candidates for insulation for clothing, wrap-around items such as hoses, and refrigeration units.

Cross-linked silica-based aerogels with polymeric materials, as well as incorporating a flexible linkage into the underlying metal oxide, have been proven to improve strength and resilience over their native, or non-cross-linked, counterparts without adversely affecting porosity and density. In this invention, high-temperature, stable, all-organic polyimide aerogels are prepared as reacting linear polyimide chains with a functional monomer to create branchings that are further room-temperature-cured with multifunctional isocyanate to form a three-dimensional network.

Posted in: Briefs, Materials, Heat resistant materials, Materials properties, Polymers

Multilayer Insulation Systems

Applications exist where cryogenic fluids or liquefied gases are required, and in magnetic resonance imaging (MRI), power transmission in big cities, food freezing, and blood banks.

Cryogenic fluid management (CFM) is a critical technical area that is needed for the successful development of future space exploration. A key challenge is the storability of LH2, LCH4, and LOX propellants for long durations. The storage tanks must be well insulated to prevent over-pressurization and venting, which lead to unacceptable propellant losses for long-duration missions to Mars and beyond.

Posted in: Briefs, Materials, Liquid propellants, Spacecraft fuel, Thermal management, Thermal management, Storage, Insulation

Colorimetric Indicator for Detection of AF-M315E

John F. Kennedy Space Center, Florida

An easy and instant method of detection was needed for AF-M315E, a “green” propellant that produces very little vapor. This makes it hard to detect by smell or other active sensors.

Posted in: Briefs, Materials, Sensors and actuators, Sensors and actuators, Propellants, Chemicals, Test equipment and instrumentation

Oriented Nanofibers Embedded in a Polymer Matrix

Lyndon B. Johnson Space Center, Houston, Texas

A method of forming a composite of embedded nanofibers in a polymer matrix with a high degree of alignment has been created using a nanofiber continuous fiber (NCF) system. This innovation incorporates nanofibers in a plastic matrix forming agglomerates, and then uniformly distributes them by exposing the agglomerates to hydrodynamic stresses that force the agglomerates to break apart. In combination, or additionally, elongational flow is used to achieve small diameters and alignment.

Posted in: Briefs, Materials, Forming, Composite materials, Fibers, Nanomaterials, Polymers

Low-Scatter Starshade Edges

This technology has applications in flexible optical masks, apertures, and encoders where sharp edges and material robustness are important.

A starshade occulter is a large space structure whose shape is specially designed to produce a diffraction pattern in starlight that can aid a telescope in direct imaging of exoplanets. The diffraction pattern produces extremely high-contrast dark regions in the starshade’s shadow on the order of 10-9 or 10-10. To do so, the edge shape of the structure must be held to extremely tight tolerances. In addition, potentially obscuring glint light from the Sun must be minimized to prevent loss of contrast.

Posted in: Briefs, Materials, Imaging, Imaging and visualization, Optics, Imaging, Imaging and visualization, Optics, Spacecraft

Processing and Damage Tolerance of Continuous Carbon Fiber Composites Containing Puncture-Self-Healing Thermoplastic Matrix

The initiation and propagation of damage ultimately results in failure of aircraft structural components. Often, impact damage is difficult to identify in-service, and hence design of continuous carbon fiber reinforced polymer (CFRP) composite structure involves up to a 50% knockdown in the undamaged failure strength allowable. If damage is identified in a composite structure, the vehicle must be grounded for structural repair. This involves the grinding away of damaged regions and drilled holes to secure patches. By providing a polymer matrix with the ability to self-heal after impact damage is incurred, vehicle safety is greatly improved by increasing the design allowable for strength, resulting in more efficient CFRP structure.

Posted in: Briefs, Materials, Aircraft structures, Composite materials, Fibers, Materials properties, Polymers, Thermoplastics

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