Materials & Coatings

Bonding by Hydroxide-Catalyzed Hydration and Dehydration

Room-temperature process can be varied to suit optical and non-optical applications.

A simple, inexpensive method for bonding solid objects exploits hydroxidecatalyzed hydration and dehydration to form silicatelike networks in thin surface and interfacial layers between the objects. (Silicatelike networks are chemical-bond networks similar to, but looser than, those of bulk silica). The method can be practiced at room temperature or over a wide range of temperatures.

Posted in: Briefs, Materials, Joining, Chemicals

CHEM-Based Self-Deploying Planetary Storage Tanks

A document proposes self-deploying storage tanks, based on the cold elastic hibernated memory (CHEM) concept, to be used on remote planets. The CHEM concept, described in previous NASA Tech Briefs articles, involves the use of open-cell shape-memory-polymer (SMP) foam sandwich structures to make lightweight, space-deployable structures that can be compressed for storage and can later be expanded, then rigidified for use.

Posted in: Briefs, TSP, Materials, Containers, Storage, Foams

Sequestration of Single-Walled Carbon Nanotubes in a Polymer

The nanotubes would be solubilized for incorporation into lightweight composites.

Sequestration of single-walled carbon nanotubes (SWCNs) in a suitably chosen polymer is under investigation as a means of promoting the dissolution of the nanotubes into epoxies. The purpose of this investigation is to make it possible to utilize SWCNs as the reinforcing fibers in strong, lightweight epoxy-matrix/ carbon-fiber composite materials. SWCNs are especially attractive for use as reinforcing fibers because of their stiffness and strength-to-weight ratio: Their Young’s modulus has been calculated to be 1.2 TPa, their strength has been calculated to be as much as 100 times that of steel, and their mass density is only one-sixth that of steel.

Posted in: Briefs, Materials, Composite materials, Fibers, Nanotechnology, Polymers

Foam Core Shielding for Spacecraft

A foam core shield (FCS) system is now being developed to supplant multilayer insulation (MLI) systems heretofore installed on spacecraft for thermal management and protection against meteoroid impacts. A typical FCS system consists of a core sandwiched between a face sheet and a back sheet. The core can consist of any of a variety of low-to- medium-density polymeric or inorganic foams chosen to satisfy application-specific requirements regarding heat transfer and temperature.

Posted in: Briefs, Materials, Thermal management, Foams, Spacecraft

Modeling Metamaterials Leads to Advance in Cloaking System Prototype

In efforts to use metamaterials to construct the world’s first working prototype of an invisibility cloak, researchers relied on multiphysics software.

Modeling software is generally used to show the fields and flows that are impossible to see with the eye or instruments. A group of researchers has done just the opposite: They ran computer simulations that showed it should be possible to fabricate the metamaterials necessary to build an “invisibility cloak” that makes an object invisible to certain frequencies.

Posted in: Briefs, Materials, Computer simulation, Research and development, Visibility

Strong, Lightweight, Porous Materials

These materials, derived from silica aerogels, can be tailored to have superior properties.

A new class of strong, lightweight, porous materials has been invented as an outgrowth of an effort to develop reinforced silica aerogels. The new material, called X-Aerogel is less hygroscopic, but no less porous and of similar density to the corresponding unmodified aerogels. However, the property that sets XAerogels apart is their mechanical strength, which can be as much as two and a half orders of magnitude stronger that the unmodified aerogels. X-Aerogels are envisioned to be useful for making extremely lightweight, thermally insulating, structural components, but they may also have applications as electrical insulators, components of laminates, catalyst supports, templates for electrode materials, fuel-cell components, and filter membranes.

Posted in: Briefs, TSP, Materials, Lightweight materials, Materials properties


Fiber geometries could be tailored for pumping, filtering, mixing, separating, and other effects.

Nanowicks are dense mats of nanoscale fibers that are expected to enable the development of a variety of novel capillary pumps, filters, and fluidic control devices. Nanowicks make it possible obtain a variety of novel effects, including capillary pressures orders of magnitude greater than those afforded by microscale and conventional macroscale wicks. While wicking serves the key purpose of transporting fluid, the nanofiber geometry of a nanowick makes it possible to exploit additional effects — most notably, efficient nanoscale mixing, fluidic effects for logic or control, and ultrafiltration (in which mats of nanofibers act as biomolecular sieves).

Posted in: Briefs, TSP, Materials, Fibers, Nanomaterials

Lightweight Thermal Protection System for Atmospheric Entry

The material withstands up to 1,970 K to protect wing leading edges and nose caps on hypersonic vehicles.

TUFROC (Toughened Uni-piece Fibrous Reinforced Oxidation- resistant Composite) has been developed as a new thermal protection system (TPS) material for wing leading edge and nose cap applications. The composite withstands temperatures up to 1,970 K, and consists of a toughened, high-temperature surface cap and a low-thermal- conductivity base, and is applicable to both sharp and blunt leading edge vehicles. This extends the possible application of fibrous insulation to the wing leading edge and/or nose cap on a hypersonic vehicle.

Posted in: Briefs, TSP, Materials, Composite materials, Heat resistant materials, Lightweight materials, Spacecraft

Coating Thermoelectric Devices To Suppress Sublimation

Thermoelectric materials are covered with adherent, chemically stable metal outer layers.

A technique for suppressing sublimation of key elements from skutterudite compounds in advanced thermoelectric devices has been demonstrated. The essence of the technique is to cover what would otherwise be the exposed skutterudite surface of such a device with a thin, continuous film of a chemically and physically compatible metal. Although similar to other sublimation- suppression techniques, this technique has been specifically tailored for application to skutterudite antimonides.

Posted in: Briefs, TSP, Materials, Powder metallurgy, Coatings, colorants, and finishes, Materials properties, Metals

Rapid Fabrication of Carbide Matrix/Carbon Fiber Composites

Melt infiltration offers advantages over chemical vapor infiltration.

Composites of zirconium carbide matrix material reinforced with carbon fibers can be fabricated relatively rapidly in a process that includes a melt infiltration step. Heretofore, these and other ceramic matrix composites have been made in a chemical vapor infiltration (CVI) process that takes months. The finished products of the CVI process are highly porous and cannot withstand temperatures above 3,000 °F (≈1,600 °C). In contrast, the melt-infiltration-based process takes only a few days, and the composite products are more nearly fully dense and have withstood temperatures as high as 4,350 °F (≈2,400 °C) in a highly oxidizing thrust chamber environment. Moreover, because the meltinfiltration- based process takes much less time, the finished products are expected to cost much less.

Posted in: Briefs, Materials, Fabrication, Composite materials

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