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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Additive Manufacture of Refractory Metal Green Propulsion Thrusters

High temperature refractory metals are required for a number of high temperature propulsion applications. Refractory metals are expensive, difficult to manufacture with high buy-to-fly ratios, and few vendors. Additive manufacture (AM) is used to produce C103, Molybdenum (Mo), and Tungsten (W) reaction chamber and thrust stand-off as well as Iridium ultra-fine lattice catalysts for integration into 1 N green propulsion thrusters. After printing components underwent post-processing to include heat treatment, surface finish modification, inspection, integration, and testing. Properly utilized AM overcomes existing manufacture limitations by greatly increasing design flexibility, material options, decrease price, decrease lead-time, and increase the commercial supply base.

Omar Mireles↗
NASA NTRS1991

High temperature structural fibers: Status and needs

The key to high temperature structural composites is the selection and incorporation of continuous fiber reinforcement with optimum mechanical, physical, and chemical properties. Critical fiber property needs are high strength, high stiffness, and retention of these properties during composite fabrication and use. However, unlike polymeric composites where all three requirements are easily achieved with a variety of commercially available carbon-based fibers, structural fibers with sufficient stiffness and strength retention for high temperature metal, intermetallic, and ceramic composites are not available. The objective here is to discuss in a general manner the thermomechanical stability problem for current high performance fibers which are based on silicon and alumina compositions. This is accomplished by presenting relevant fiber property data with a brief discussion of potential underlying mechanisms. From this general overview, some possible materials engineering approaches are suggested which may lead to minimization and/or elimination of this critical stability problem for current high temperature fibers.

Dicarlo, James A.↗
NASA NTRS1994

X-Ray Absorption Spectroscopy in High Temperature Oxidation of Metals and Alloys

An experimental technique is described that allows for the joint study of the kinetics and of the oxide structure during the high temperature oxidation of metal surfaces. Oxygen is supplied at the metal through an electrochemical oxygen pump and the oxygen pressure, at the metal surface, is measured during oxidation by a YSZ (yttria stabilized zirconia) oxygen sensor. XAS (x-ray absorption spectroscopy) is performed in fluorescence mode at the cation K edge and after each oxidation step. An appropriate analysis of the XAS spectra could provide information on both the oxidation kinetics and oxide structure. Experimental data on the high temperature oxidation of nickel, cobalt, and Fe(64%)Ni(36%) alloy, at low oxygen pressure, are reported and analyzed according to the proposed data reduction. These results indicate the presented technique to be particularly suitable for studying the hot corrosion of oxide film too thick for common surface spectroscopy (AUGER, ESCA) and too thin for conventional thermogravimetric technique.

Daniele Gozzi↗
NASA NTRS1980

Method of producing silicon

A liquid reactant injector assembly suited for the injection of liquid reactant into a high temperature metal reductant vapor and carrier gas stream for the production of metal is presented. The assembly is especially adapted for the continuous production of high purity silicon by the reduction of SiCl4 with sodium. The assembly includes a refractory-lined, hollow metal shell having ten equally-spaced, concentric, radially directed ports provided in the shell and wall. A hydraulic, atomizing type spray nozzle is mounted in each of the ports recessed from the inner wall surface.

Wolf, C. B.↗
NASA NTRS1982

High-temperature fatigue in metals

The presentation focuses primarily on the progress we at NASA Lewis Research Center have made. The understanding of the phenomenological processes of high temperature fatigue of metals for the purpose of calculating lives of turbine engine hot section components is discussed. Improved understanding resulted in the development of accurate and physically correct life prediction methods such as Strain-Range Partitioning for calculating creep fatigue interactions and the Double Linear Damage Rule for predicting potentially severe interactions between high and low cycle fatigue. Examples of other life prediction methods are also discussed.

Gary R. Halford↗
NASA NTRS1989

Metal matrix composite micromechanics - In situ behavior influence on composite properties

The influence of in situ fiber and matrix properties (such as in situ matrix strength and the interphase degradation) of high-temperature metal matrix composites (HTMMCs) on the unidirectional stress-strain behavior of the composite is examined using results of a numerical investigation of a SiC/Ti-15-3-3-3 unidirectional composite. It is shown that a reduction of the in situ matrix strength substantially decreases the transverse and the longitudinal tensile/compressive strengths, as well as the in-plane shear strength, of the composite. The interphase degradation affects the behavior in transverse tension/compression drastically; both the ultimate strength and strain showed significant reductions. The higher use temperature results in a reduction in the ultimate strength and in the initial tangential modulus for compression and for in-plane shear loading.

Murthy, P. L. N.↗
NASA NTRS1977

Metallic hot wire anemometer

A hot wire anemometer is described which has a body formed of heat resistant metal such as an alloy high in nickel content which supports a probe wire disposed in a V groove in the body. The V groove contains a high temperature ceramic adhesive that partially encompasses the downstream side of the probe wire. Mechanical and electrical connection to the probe wire is achieved through conductive support rods that are constructed of the same high temperature metal, insulation between the body and the conductor rods being provided by a coating of an oxide of the same material which coating is formed in situ. The oxide coating insulates the conductor rods from the body, mechanically fixes the conductors within the body, and maintains its integrity at elevated temperatures.

Lemos, F. R.↗
NASA NTRS2001

Combustion of Metals in Reduced-Gravity and Extraterrestrial Environments

As a result of the ongoing exploration of Mars and the several unmanned and possibly manned missions planned for the near future, increased attention has been given to the use of the natural resources of the planet for rocket propellant production and energy generation. Since the atmosphere of Mars consists of approximately 95% carbon dioxide (CO2), this gas is the resource of choice to be employed for these purposes. Since many metals burn vigorously with CO2, these may be used as an energy source or as propellants for a research vehicle on the surface of Mars. Shafirovich and Goldshleger conducted experiments with spherical particles up to 2.5 mm in diameter and found that the burning process was controlled by diffusion and that the particles exhibited pulsating combustion due to superheating of the Mg vapor trapped inside a protective oxide shell. They also proposed a reaction mechanism based on the gas-phase reaction, Mg + CO2 yields MgO + CO and the heterogeneous reaction Mg + CO yields MgO + C occurring on the sample surface. In all the above studies with large Mg particles, the burning process is invariably influenced by strong convective currents that accelerate the combustion reaction and shorten the burning times. Although these currents are nearly absent in the burning of small particles, the high emissivity of the flames, rapid reaction, and small length scales make the gathering of any useful information on burning rates and flame structure very difficult. The goal of this investigation is to provide a detailed study of flame structure by taking advantage of large, free-floating spherical metal samples and their corresponding long burning times available in a weightless environment. The use of reduced gravity is essential to eliminate the intrusive buoyant flows that plague high temperature metal reactions, to remove the destructive effect of gravity on the shape of molten metal samples, and to study the combustion behavior of metals in the presence of solid oxides undisturbed by natural convection. This work presents the most complete modeling of metal particle burning to date for Mg with CO2 and O2.

Branch, M. C.↗
NASA NTRS1989

Finite element applications to explore the effects of partial bonding on metal matrix composite properties

The mechanics of materials approach (definition of E, G, Nu, and Alpha) and the finite element method are used to explore the effects of partial bonding and fiber fracture on the behavior of high temperature metal matrix composites. Composite ply properties are calculated for various degrees of disbonding to evaluate the sensitivity of these properties to the presence of fiber/matrix disbonding and fiber fracture. The mechanics of materials approach allows for the determination of the basic ply material properties needed for design/analysis of composites. The finite element method provides the necessary structural response (forces and displacements) for the mechanics of materials equations. Results show that disbonding of fractured fibers affect only E sub (111) and alpha sub (111) significantly.

Caruso, J. J.↗
NASA NTRS1989

Finite element applications to explore the effects of partial bonding on metal matrix composite properties

The mechanics of materials approach (definition of E, G, nu, and alpha) and the finite element method are used to explore the effects of partial bonding and fiber fracture on the behavior of high temperature metal matrix composites. Composite ply properties are calculated for various degrees of disbonding to evaluate the sensitivity of these properties to the presence of fiber/matrix disbonding and fiber fracture. The mechanics of materials approach allows for the determination of the basic ply material properties needed for design/analysis of composites. The finite element method provides the necessary structural response (forces and displacements) for the mechanics of materials equations. Results show that disbonding of fractured fibers affect only E-l(11) and alpha-l(11) significantly.

Caruso, J. J.↗
NASA NTRS1993

Material requirements for the High Speed Civil Transport

Under NASA-sponsored High Speed Research (HSR) programs, the materials and processing requirements have been identified for overcoming the environmental and economic barriers of the next generation High Speed Civil Transport (HSCT) propulsion system. The long (2 to 5 hours) supersonic cruise portion of the HSCT cycle will place additional durability requirements on all hot section engine components. Low emissions combustor designs will require high temperature ceramic matrix composite liners to meet an emission goal of less than 5g NO(x) per Kg fuel burned. Large axisymmetric and two-dimensional exhaust nozzle designs are now under development to meet or exceed FAR 36 Stage III noise requirements, and will require lightweight, high temperature metallic, intermetallic, and ceramic matrix composites to reduce nozzle weight and meet structural and acoustic component performance goals. This paper describes and discusses the turbomachinery, combustor, and exhaust nozzle requirements of the High Speed Civil Transport propulsion system.

Stephens, Joseph R.↗
NASA NTRS1993

METal matrix composite ANalyzer (METCAN): Theoretical manual

This manuscript is intended to be a companion volume to the 'METCAN User's Manual' and the 'METAN Demonstration Manual.' The primary purpose of the manual is to give details pertaining to micromechanics and macromechanics equations of high temperature metal matrix composites that are programmed in the METCAN computer code. The subroutines which contain the programmed equations are also mentioned in order to facilitate any future changes or modifications that the user may intend to incorporate in the code. Assumptions and derivations leading to the micromechanics equations are briefly mentioned.

Murthy, P. L. N.↗
NASA NTRS1972

Mission oriented R and D and the advancement of technology: The impact of NASA contributions, volume 2

NASA contributions to the advancement of major developments in twelve selected fields of technology are presented. The twelve fields of technology discussed are: (1) cryogenics, (2) electrochemical energy conversion and storage, (3) high-temperature ceramics, (4) high-temperature metals (5) integrated circuits, (6) internal gas dynamics (7) materials machining and forming, (8) materials joining, (9) microwave systems, (10) nondestructive testing, (11) simulation, and (12) telemetry. These field were selected on the basis of both NASA and nonaerospace interest and activity.

Robbins, M. D.↗
NASA NTRS1973

Development of porcelain enamel passive thermal control coatings

A white porcelain enamel coating was developed for application to high temperature metallic alloy substrates on spacecraft. The coating consists of an optically opacifying zirconia pigment, a lithia-zirconia-silica frit, and an inorganic pigment dispersant. The coating is fired at 1000 to 1150 C to form the enamel. The coating has a solar absorptance of 0.22 and a total normal emittance of 0.82 for a 0.017 cm thick coating. The coating exhibits excellent adhesion, cleanability, and integrity and is thermal shock resistant to 900 C. Capability to coat large panels has been demonstrated by successful coating of 30 cm x 30 cm Hastelloy X alloy panels. Preliminary development of low temperature enamels for application to aluminum and titanium alloy substrates was initiated. It was determined that both leaded and leadless frits were feasible when applied with appropriate mill fluxes. Indications were that opacification could be achieved at firing temperatures below 540 C for extended periods of time.

Levin, H.↗
NASA NTRS1973

Electric vehicle battery research and development

High energy battery technology for electric vehicles is reviewed. The state-of-the-art in conventional batteries, metal-gas batteries, alkali-metal high temperature batteries, and organic electrolyte batteries is reported.

Schwartz, H. J.↗