Materials & Coatings

A Model of Reduced Kinetics for Alkane Oxidation Using Constituents and Species for N-Heptane

The reduction of elementary or skeletal oxidation kinetics to a subgroup of tractable reactions for inclusion in turbulent combustion codes has been the subject of numerous studies. The skeletal mechanism is obtained from the elementary mechanism by removing from it reactions that are considered negligible for the intent of the specific study considered. As of now, there are many chemical reduction methodologies.

Posted in: Briefs, Materials, Analysis methodologies, Mathematical models, Chemicals, Combustion and combustion processes

Thermally Conductive Tape Based on Carbon Nanotube Arrays

To increase contact conductance between two mating surfaces, a conductive “tape” has been developed by growing dense arrays of carbon nanotubes (CNTs, graphite layers folded into cylinders) on both sides of a thermally conductive metallic foil. When the two mating surfaces are brought into contact with the conductive tape in between, the CNT arrays will adhere to the mating surface. The van der Waals force between the contacting tubes and the mating surface provides adhesion between the two mating surfaces. Even though the thermal contact conductance of a single tube-to-tube contact is small, the tremendous amount of CNTs on the surface leads to a very large overall contact conductance.

Posted in: Briefs, Materials, Joining, Adhesives and sealants, Conductivity, Nanomaterials, Thermal testing

Lightweight, Ultra-High-Temperature, CMC-Lined Carbon/Carbon Structures

This refractory composite material is applicable to defense vehicles, combustion chambers, rocket nozzles, hot gas generators, and valves using both liquid and solid propellants.

lished engineering material used extensively in aerospace. The beneficial properties of C/C include high strength, low density, and toughness. Its shortcoming is its limited usability at temperatures higher than the oxidation temperature of carbon — approximately 400 °C. Ceramic matrix composites (CMCs) are used instead, but carry a weight penalty. Combining a thin laminate of CMC to a bulk structure of C/C retains all of the benefits of C/C with the high temperature oxidizing environment usability of CMCs.

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

Two Catalysts for Selective Oxidation of Contaminant Gases

One oxidizes halocarbons and ammonia; the other oxidizes ammonia.

Two catalysts for the selective oxidation of trace amounts of contaminant gases in air have been developed for use aboard the International Space Station. These catalysts might also be useful for reducing concentrations of fumes in terrestrial industrial facilities — especially facilities that use halocarbons as solvents, refrigerant liquids, and foaming agents, as well as facilities that generate or utilize ammonia.

Posted in: Briefs, Materials, Catalysts, Air supply, Air supply, Gases, Hazardous materials, Spacecraft

Nanoscale Metal Oxide Semiconductors for Gas Sensing

A report describes the fabrication and testing of nanoscale metal oxide semiconductors (MOSs) for gas and chemical sensing. This document examines the relationship between processing approaches and resulting sensor behavior. This is a core question related to a range of applications of nanotechnology and a number of different synthesis methods are discussed: thermal evaporation-condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed, providing a processing overview to developers of nanotechnology-based systems.

Posted in: Briefs, TSP, Materials, Sensors and actuators, Sensors and actuators, Gases, Nanotechnology, Semiconductors

Carbon Nanofibers Synthesized on Selective Substrates for Nonvolatile Memory and 3D Electronics

This method can impact the application of carbon nanofiber tubes in 3D electronics applications.

A plasma-enhanced chemical vapor deposition (PECVD) growth technique has been developed where the choice of starting substrate was found to influence the electrical characteristics of the resulting carbon nanofiber (CNF) tubes. It has been determined that, if the tubes are grown on refractory metallic nitride substrates, then the resulting tubes formed with dc PECVD are also electrically conducting.

Posted in: Briefs, Materials, Electronic equipment, Electronic equipment, Conductivity, Nanomaterials

Nanoparticle/Polymer Nanocomposite Bond Coat or Coating

This innovation addresses the problem of coatings (meant to reduce gas permeation) applied to polymer matrix composites spalling off in service due to incompatibility with the polymer matrix. A bond coat/coating has been created that uses chemically functionalized nanoparticles (either clay or graphene) to create a barrier film that bonds well to the matrix resin, and provides an outstanding barrier to gas permeation.

Posted in: Briefs, TSP, Materials, Coatings Colorants and Finishes, Coatings, colorants, and finishes, Composite materials, Nanomaterials, Polymers

Self-Assembling Hydrophobin Useful for Coating Surfaces

This heat-tolerant compound can be used to treat medical implants.

This technology provides isolated polynucleotides comprising a nucleotide sequence encoding a mature thermophillic hydrophobin polypeptide suitable for a recombinant DNA technology production process. This compound self-assembles at interfaces and is applicable to a broad variety of surfaces. It is extremely heat-tolerant — up to 50 °C. Applications include coatings for medical implants and drug delivery solutions.

Posted in: Briefs, MDB, Briefs, Coatings & Adhesives, Materials, Bio-Medical, Implants & Prosthetics, Medical, Prostheses and implants, Coatings Colorants and Finishes, Coatings, colorants, and finishes, Materials properties

Fabrication of Lanthanum Telluride 14-1-11 Zintl High-Temperature Thermoelectric Couple

This methodology will aid device fabrication for waste energy recovery applications in cars, power plants, and industrial processes and machinery.

The development of more efficient thermoelectric couple technology capable of operating with high-grade heat sources up to 1,275 K is key to improving the performance of radioisotope theroelectric generators. Lanthanum telluride La3–xTe4 and 14-1-11 Zintls (Yb14MnSb11) have been identified as very promising materials.

Posted in: Briefs, TSP, Materials, Connectors and terminals, Connectors and terminals, Nuclear energy, Product development, Heat resistant materials, Electro-thermal engines

Modeling of Alkane Oxidation Using Constituents and Species

This methodology is of interest to automobile manufacturers and other gas-turbine engine manufacturers.

It is currently not possible to perform simulations of turbulent reactive flows due in particular to complex chemistry, which may contain thousands of reactions and hundreds of species. This complex chemistry results in additional differential equations, making the numerical solution of the equation set computationally prohibitive. Reducing the chemical kinetics mathematical description is one of several important goals in turbulent reactive flow modeling. A chemical kinetics reduction model is proposed for alkane oxidation in air that is based on a parallel methodology to that used in turbulence modeling in the context of the Large Eddy Simulation. The objective of kinetic modeling is to predict the heat release and temperature evolution. This kinetic mechanism is valid over a pressure range from atmospheric to 60 bar, temperatures from 600 K to 2,500 K, and equivalence ratios from 0.125 to 8. This range encompasses diesel, HCCI, and gas-turbine engines, including cold ignition.

Posted in: Briefs, Materials, Computational fluid dynamics, Mathematical models, Chemicals

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