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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Steam Rankine Solar Receiver, phase 2

A steam rankine solar receiver (SRSR) based on a tubular concept was designed and developed. The SRSR is an insulated, cylindrical coiled tube boiler which is mounted at the focal plane of a fully tracking parabolic solar reflector. The concentrated solar energy received at the focal plane is then transformed to thermal energy through steam generation. The steam is used in a small Rankine cycle heat engine to drive a generator for the production of electrical energy. The SRSR was designed to have a dual mode capability, performing as a once through boiler with and without reheat. This was achieved by means of two coils which constitute the boiler. The boiler core size of the SRSR is 17.0 inches in diameter and 21.5 inches long. The tube size is 7/16 inch I.D. by 0.070 inch wall for the primary, and 3/4 inch I.D. by 0.125 inch wall for the reheat section. The materials used were corrosion resistant steel (CRES) type 321 and type 347 stainless steel. The core is insulated with 6 inches of cerablanket insulation wrapped around the outer wall. The aperture end and the reflector back plate at the closed end section are made of silicon carbide. The SRSR accepts 85 kwth and has a design life of 10,000 hrs when producing steam at 1400 F and 2550 psig.

Deanda, L. E.↗
NASA NTRS1982

Bearings: Technology and needs

A brief status report on bearing technology and present and near-term future problems that warrant research support is presented. For rolling element bearings a material with improved fracture toughness, life data in the low Lambda region, a comprehensive failure theory verified by life data and incorporated into dynamic analyses, and an improved corrosion resistant alloy are perceived as important needs. For hydrodynamic bearings better definition of cavitation boundaries and pressure distributions for squeeze film dampers, and geometry optimization for minimum power loss in turbulent film bearings are needed. For gas film bearings, foil bearing geometries that form more nearly optimum film shapes for maximum load capacity, and more effective surface protective coatings for high temperature operation are needed.

Anderson, W. J.↗
NASA NTRS1981

Poly/phenylquinoxalines/ containing ethynyl groups

The synthesis of high molecular weight linear poly(phenylquinoxalines) containing pendant ethynyl groups is reported, where thermally-induced reactions of the ethynyl groups provided insoluble, cross-linked polymers with high glass transition temperatures. The ethynyl-containing polymer exhibited fair to poor processability by compression molding due to the thermal reaction of the ethynyl groups, which inhibited polymer flow, depending on ethynyl density. This class of polymers is not expected to be useful as laminating resins or adhesives, due to the processing difficulties. Use for them may be found, however, as solvents and corrosion-resistant high-temperature coatings.

Hergenrother, P. M.↗
NASA NTRS1982

Long term compatibility of nitrogen tetroxide with metals - Results at the ten-year milestone

Analyses and results are reported of a test program to establish the effects of long-term (10 years or more) contact of materials with nitrogen textroxide MON-1 for the purpose of designing chemical propulsion system components which can be used for current as well as future planetary spacecraft. The test materials included aluminum alloy, corrosion-resistant steel, titanium alloy, and nickel. The weight and appearance of each specimen were observed, including the presence of deposits, etching, pitting, and cracking. Aluminum alloy and steel were rated satisfactory with minor reservations, titanium alloy was satisfactory, and nickel was unsatisfactory. Criteria for ratings are shown.

Moran, C. M.↗
NASA NTRS1982

Vacuum Sputtered and Ion-Plated Coatings for Wear and Corrosion Protection

The plasma or ion-assisted coating techniques such as sputtering and ion plating are discussed in view of wear and corrosion protection. The basic processes and the unique features of the technique are discussed in regard to the synthesis and development of high reliability wear and corrosion resistant films. The ions of the plasma which transfer energy, momentum, and charge to the substrate and the growing films can be beneficially used. As a result, coating adherence and cohesion is improved. Favorable morphological growth such as high density and porosity-free films can be developed, and residual stresses can be reduced.

Spalvins, T.↗
NASA NTRS1982

Propellant/material compatibility program and results: Ten-year milestones

The analyses and results of a test program to establish the effects of long term (10 years or more) contact of materials with earth-storable propellants for the purpose of designing chemical propulsion system components which are used for current as well as future planetary spacecraft are described. The period from the publication of JPL TM 33-779 IN 1976 through the testing accomplished in 1981 is covered. The following propellants are reported herein: hydrazine, monomethylhydrazine and nitrogen tetroxide. Materials included the following: aluminum alloys, corrosion resistant steels and a titanium alloy. The results of the testing of more than 80 specimens are included. Material ratings relative to the ten year milepost were assigned. Some evidence of propellant decomposition was found. Titanium is rated as acceptable for ten year applications. Aluminum and stainless steel alloys are also rated as acceptable with few restrictions.

Moran, C.↗
NASA NTRS1983

Process for the production of metal nitride sintered bodies and resultant silicon nitride and aluminum nitride sintered bodies

A process for the manufacture of metal nitride sintered bodies, in particular, a process in which a mixture of metal nitrite powders is shaped and heated together with a binding agent is described. Of the metal nitrides Si3N4 and AIN were used especially frequently because of their excellent properties at high temperatures. The goal is to produce a process for metal nitride sintered bodies with high strength, high corrosion resistance, thermal shock resistance, thermal shock resistance, and avoidance of previously known faults.

Yajima, S.↗
NASA NTRS1983

Effect of carbide distribution on rolling-element fatigue life of AMS 5749

Endurance tests with ball bearings made of corrosion resistant bearing steel which resulted in fatigue lives much lower than were predicted are discussed. Metallurgical analysis revealed an undesirable carbide distribution in the races. It was shown in accelerated fatigue tests in the RC rig that large, banded carbides can reduce rolling element fatigue life by a factor of approximately four. The early spalling failures on the bearing raceways are attributed to the large carbide size and banded distribution.

Parker, R. J.↗
NASA NTRS1983

Long term compatability of hydrazine with metals: Results at the ten-year milestone

A test program to establish the effects of long term contact of materials with hydrazine for the purpose of designing chemical propulsion system components which can be used for current as well as future planetary spacecraft was analyzed. Materials included the following: aluminum alloys, corrosion resistant steels, and a titanium alloy. Material ratings relative to the 10 year milepost are assigned. The propellant was found to be stable. With minor exceptions, the materials tested were rated acceptable for a 10 year mission.

Moran, C. M.↗
NASA NTRS1982

Fusible pellet transport and storage of heat

A new concept for both transport and storage of heat at high temperatures and heat fluxes is introduced and the first steps in analysis of its feasibility is taken. The concept utilizes the high energy storage capability of materials undergoing change of phase. The phase change material, for example a salt, is encapsulated in corrosion resistant sealed pellets and transported in a carrier fluid to heat source and storage. Calculations for heat transport from a typical solar collector indicate that the pellet mass flow rates are relatively small and that the required pumping power is only a small fraction of the energy transport capability of the system. Salts and eutectic salt mixtures as candidate phase change materials are examined and discussed. Finally, the time periods for melting or solidification of sodium chloride pellets is investigated and reported.

Bahrami, P. A.↗
NASA NTRS1982

Oxide dispersion hardened mechanically alloyed materials for high temperatures

The procedure of mechanical alloying makes it possible to obtain, with the aid of powder-metallurgy techniques, alloys that consist of a metallic matrix in which very fine oxide particles are dispersed. Mechanically alloyed compound powders can be used for making either forged or hot-rolled semifinished products. For these products, dispersion strengthening and precipitation hardening has been combined. At high temperatures, the strength characteristics of the alloy are determined by both dispersion hardening and by precipitation hardening processes. The effect produced by each process is independent of that due to the other. Attention is given to the principle of mechanical alloying developed by Benjamin (1970, 1976), the strength characteristics of mechanically alloyed materials, the corrosion resistance of mechanically alloyed material at high temperatures, and the preparation and characteristics of the alloy MA 6000 E.

Benjamin, J. S.↗
NASA NTRS1984

Status of Understanding for Bearing Materials

The structural materials and potential failure modes for high technology aircraft gas turbine bearings are reviewed. Among the failure modes discussed for iron-base through-hardened bearing materials are fatigue, surface distress, and corrosion. It is shown that the sub-surface initiated rolling-contact fatigue failure mode is reasonably well understood and in most cases can be controlled by proper material selection and design. Current bearing materials provide long life and high reliability in existing applications. A new generation of materials are being developed which will provide improved fracture toughness, better corrosion resistance, and a further extension of bearing fatigue life. Bearing problems due to surface distress, caused by a variety of surface and near surface anomalies, are less well understood. This area will require the implementation of an interdisciplinary effort to improve the level of understanding of metallic surface-lubricant reactions and interactions.

E N Bamberger↗
NASA NTRS1984

Status of Understanding for Seal Materials

Material selection for mainshaft face and ring seals, labyrinth seals, accessory gearbox face seals, and lip seals are discussed in light of tribology requirements and a given seal application. Carbon graphite has been found to be one of the best sealing materials and it is widely used in current gas turbine mainshaft and accessory gearbox seals. Its popularity is due to its unique combination of properties which consists of dimensional stability, corrosion resistance, low friction, good self lubricating characteristics, high thermal conductivity and low thermal expansion, the latter two properties combining to provide good thermal shock resistance. A brief description of the seals and the requirements they must meet are discussed to provide insight into the limitations and advantages of the seals in containing the lubricant. A forecast is made of the operational requirements of main shaft and gearbox seals for advanced engines and candidate materials and coatings that may satisfy these advanced engine requirements.

P F Brown↗
NASA NTRS1984

Processing of sintered alpha SiC

Processing methods of sintered alpha SiC for engine applications are developed in a cost effective manner, using a submicron sized powder blended with sintering aids (boron and carbon). The processes for forming a green powder compact, such as dry pressing, cold isostatic pressing and green machining, slip casting, aqueous extrusion, plastic extrusion, and injection molding, are described. Dry pressing is the simplest route to component fabrication, and is carried out at approximately 10,000 psi pressure, while in the cold isostatic method the pressure could go as high as 20,000 psi. Surfactants are added to control settling rates and casting characteristics in the slip casting. The aqueous extrusion process is accomplished by a hydraulic ram forcing the aqueous mixture through a die. The plastic forming processes of extrusion and injection molding offer the potential of greater diversity in shape capacity. The physical properties of sintered alpha SiC (hardness, Young's modulus, shear modulus, and thermal diffusivity) are extensively tested. Corrosion resistance test results of silicon carbide are included.

Storm, R. S.↗
NASA NTRS1985

Spray Application of Rapidly Solidified Metals

Fast and economical process now available. New process applies rapidly solidified (RS) metal coatings to substrates. RS metals made directly from molten material. Have amorphous or microcrystalline structures and yield coatings having superior wear and corrosion resistance. Mixture of RS metal powder and peening particles sprayed from nozzle against surface coated. Powder and peening particles strike surface simultaneously, and impact bonds powder to surface as uniform coating. New process, which employs shot peening, is safe, fast, and inexpensive.

Chu, H. P.↗
NASA NTRS1985

Low-Temperature Seal for Actuator Rod

Combination bearing and seal used on Space Shuttle functions reliably at temperatures as low as - 160 degrees F and as high as + 130 degrees F. Corrosion-resistant stainless-steel spacer separates secondary and primary seals in both old and new versions of seal assembly. In new version, combination of flexible sealing lip and bridge is less susceptible to cracking at low temperatures.

Lindfors, R. J.↗
NASA NTRS1984

Study of the pore structure of ceramics prepared by the slip casting method

The porosity of the slip cast Si3N4 is similar to that of pressed Si3N4 formed at 2500 kg/sq cm. The porosity of cast Si oxynitride is equivalent to that of samples stressed at 10,000 kg/sq cm. Crucibles formed from these materials by slip casting have high thermal shock and corrosion resistance.

Guzman, I. Y.↗
NASA NTRS1985

Welding, Bonding and Fastening, 1984

A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Soceity, and Society of Manufacturing Engineers conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.

Buckley, J. D.↗