Materials & Coatings

Low-Density Titanium-Based Bulk Metallic Glasses with High Glass-Forming Ability

These materials can be used in gears, bearings, latches, inserts, and sheet metal.

Ti-based bulk metallic glasses (BMGs) and matrix composites (BMGMCs) are a subset of the class of materials known synonymously as amorphous metals, liquid metals, and glassy metals, described by their majority element (in atomic percent) being that of titanium. BMGs are non-crystalline metal alloys based in a wide variety of elemental systems, including zirconium, iron, nickel, hafnium, gold, platinum, palladium, and silver, among others. The vast majority of commercially utilized BMGs are based in Zr-Ti-Cu-Ni-Be or Zr-Cu-Ni-Al due to their relatively low-cost elements and large glass-forming ability (GFA), typically greater than 1 cm. BMGs have long been considered to be a material without a clear application, as the density of BMGs fits squarely between two common, highperformance crystalline alloys that BMGs are usually thought to be replacements for: steel (density = 7.8 g/cm3) and titanium (density = 4.5 g/cm3). For example, Zr-based BMGs generally fit into the range of 6 to 6.5 g/cm3, which makes them difficult to use as direct replacements for conventional materials.

Posted in: Briefs, Materials, Alloys, Glass, Materials properties
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Thermal Management Coating (TMC)

The coating uses micro-encapsulated phase-change material.

Marshall Space Flight Center, Alabama

An experimental study was conducted in conjunction with the research and development program at the NASA Marshall Space Flight Center (MSFC) on thermal protection systems (TPS) for aerospace applications, a new concept for reusable TPS material. The new system uses a micro-encapsulated phase-change material rather than an ablative material to dissipate the heat produced during supersonic flight. This new material absorbs energy as it goes through a phase change during the heating portion of the flight profile and then the energy is released as the material cools. This new TPS consists of micro-encapsulated phasechange material and a resin system to adhere the coating to the structure. The technology has been successfully tested in the hot gas tunnel (aero-thermal heating). The figure shows the test results.

Posted in: Briefs, Materials, Thermal management, Coatings, colorants, and finishes, Materials properties
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AeroHeating Tools (AHT) Suite

Lyndon B. Johnson Space Center, Houston, Texas

This suite of computer programs, called “tools,” is used to calculate local flow angles over damage sites in the Shuttle Orbiter Thermal Protection System (TPS). It provides a quick and easy way to compute cross flow angles over points of interest on the Shuttle Orbiter TPS.

Posted in: Briefs, Materials, Computer software and hardware, Thermal management, Spacecraft
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EXOS Software

Lyndon B. Johnson Space Center, Houston, Texas

An improved version of EXOS software allows for the modeling of fabrics, mixtures, and porous materials, and also provides the ability to accept hex mesh geometries. The code employs a novel numerical method, a hybrid particle finite element approach, as well as particles and elements in tandem, each modeling distinct aspects of the physics. Ellipsoidal particles are used to model contact-impact and volumetric thermomechanical response (Euler parameters provide a singularity-free description of particle rotations). Elements are used to model “strength” effects; namely, tensile inter-particle forces and elastic-plastic deviatoric deformation.

Posted in: Briefs, TSP, Electronics & Computers, Coatings & Adhesives, Materials, Software, Computer simulation, Finite element analysis, Tensile Strength
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Using Paraffin Phase Change Material to Make Optical Communication-Type Payloads Thermally Self-Sufficient for Operation in Orion Crew Module

Goddard Space Flight Center, Greenbelt, Maryland

The Orion Crew Module has a pressurized cabin of approximately 20 m3 in volume. There are a number of cold plates within the Crew Module for thermal management. An optical communication type of payload consists of electronics boxes and modems that dissipate a significant amount of heat during science operation. Generally, such payloads operate for a short term (e.g., up to one hour). If these heat-dissipating components are flown inside the Crew Module, they require heat rejection to the cold plates in the Crew Module. The waste heat is transported from the cold plate to thermal radiators located outside the Orion spacecraft. This makes such a payload thermally dependent on the Crew Module cold plates.

Posted in: Briefs, TSP, Materials, Hydrocarbons, Passenger compartments, Thermal management, Spacecraft
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Aerogel-Filled Foam Core Insulation for Cryogenic Propellant Storage

Advanced cryogenic insulation has applications in energy, medicine, food storage and packaging, and electronics.

Marshall Space Flight Center, Alabama

Current cryogenic insulation materials suffer from various drawbacks including high cost and weight, lack of structural or load-bearing capability, fabrication complexity, and property anisotropy. A need clearly exists for lightweight thermal insulation that is isotropic and structurally capable with high thermal performance, while also offering reduced fabrication and installation complexity, and lower cost.

Posted in: Briefs, Materials, Propellants, Thermal management, Storage, Foams, Insulation
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Multifunctional B/C Fiber Composites for Radiation Shielding

Marshall Space Flight Center, Alabama

A versatile, novel, multifunctional hybrid structural composite of a high-hydrogen epoxy matrix (UN-10) coupled with boron and carbon fibers (IM-7) has been developed. Prototype laminates of 18×18 in. (≈46×46 cm), with the nominal areal density of 0.35 g/cm2, were fabricated in this effort. The hydrogen atoms in the epoxy will provide shielding strength against high-energy protons, electrons, and heavy ionic species, while the boron fibers that have a high neutron cross-section will help shield against neutrons and reduce the buildup of high-energy photons from secondary reactions. The carbon fibers will provide improved mechanical strength.

Posted in: Briefs, Materials, Composite materials, Fibers
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Smart MMOD Thermal Blanket

A spacer is added to standard thermal blankets to improve MMOD shielding.

Lyndon B. Johnson Space Center, Houston, Texas

This innovation provides for significantly improved protection from micrometeoroid and orbital debris (MMOD) particles, and reliably determines the location, depth, and extent of MMOD impact damage.

Posted in: Briefs, TSP, Materials, Fabrics, Fibers, Foams, Protective equipment, Spacecraft
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Using Black Polyimide/Kevlar as a Metering Structure Multi-Layer Insulation (MLI)

This is used as an inner cover for minimizing stray light and providing micrometeoroid protection.

Goddard Space Flight Center, Greenbelt, Maryland

Metering structures of remote sensing instruments often have large openings or access holes. Shear panels that are X-shaped, such as those proposed for the Neutron Star Interior Composition Explorer (NICER), generally consist of C-channels and L-brackets to minimize structural distortion. This type of metering structure has large openings on the sides. Structural panels that have large access holes, such as those studied for the Landsat Operational Land Imager (OLI), generally consist of aluminum honeycomb panels with composite facesheets. Both types of metering structure require multilayer insulation (MLI) blankets to shield the internal components such as optics from sunlight and Earth albedo, and to minimize heat loss to 3K space by radiation. The issues of conventional MLI blankets for these metering structures include MLI sagging, stray light, and risk of micrometeoroid damage to optics.

Posted in: Briefs, TSP, Materials, Fibers, Insulation, Polymers, Protective structures
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Mechanical Carbon Materials for Aircraft Seal Applications

These materials are of interest to designers of high-speed rotating equipment such as rotary gas compressors and steam turbines.

Metallized Carbon Corporation, Ossining, New York

Modern mechanical carbon materials are being used in a wide variety of applications, including aircraft gear boxes, air turbine motor starters, and main shaft seals for both aircraft turbine engines and aircraft auxiliary power units (APUs). These self-lubricating materials are composed of fine-grained electrographite substances that are impregnated with proprietary inorganic chemicals to improve their lubricating qualities and oxidation resistance. These modern carbon-based materials are ideal for use in aircraft applications because of their low coefficient of friction, low wear rate at high sliding speed, high thermal conductivity, and resistance to oxidation in high-temperature air.

Posted in: Briefs, Materials, Lubricants, Seals and gaskets, Gas turbines
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