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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 631 records · Page 35

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NASA NTRS1982

A ceramic nozzle for the NASA-Langley 2.4-m /8.0-ft/ high temperature structures tunnel

Two materials, a refractory castable ceramic and a SiO2-SiO2 composite, were fabricated as nozzle inserts for the Langley Research Center's 2.4-m (8.0-ft) high temperature structures tunnel. The high pressure and intense heat of the CH4-air products of the combustion-gas stream limits the materials that can be used in this tunnel. The castable-ceramic material showed good resistance to erosion and the thermal loads imposed on it by the gas stream but failed in tension when subjected to high hoop stresses. The SiO2-SiO2-composite nozzle insert withstood the thermomechanical loads but eroded unacceptably with increasing test temperature and pressure.

Buckley, J. D.↗

NASA NTRS1983

Lessons learned from the development and manufacture of ceramic reusable surface insulation materials for the space shuttle orbiters

Three ceramic, reusable surface insulation materials and two borosilicate glass coatings were used in the fabrication of tiles for the Space Shuttle orbiters. Approximately 77,000 tiles were made from these materials for the first three orbiters, Columbia, Challenger, and Discovery. Lessons learned in the development, scale up to production and manufacturing phases of these materials will benefit future production of ceramic reusable surface insulation materials. Processing of raw materials into tile blanks and coating slurries; programming and machining of tiles using numerical controlled milling machines; preparing and spraying tiles with the two coatings; and controlling material shrinkage during the high temperature (2100-2275 F) coating glazing cycles are among the topics discussed.

Banas, R. P.↗

NASA NTRS1983

Method of manufacturing ceramic shaped articles

A method of manufacturing ceramic shaped articles, wherein tapes of ceramic powder material in mixture with a binder material and special additives are shaped and then articles are stamped out from said tapes and sintered in a sintering furnace is described.

Inoue, K.↗

NASA NTRS1983

Absorbable-susceptor joining of ceramic surfaces

An assembly of ceramic surfaces particularly refractory metal oxides and carbides, abutting a thin sheet of metal susceptor material are placed in a chamber of an enclosure containing inert gas. An RF coil is activated by power supply to melt the susceptor and adjacent zones of the ceramic. Reactive gas such as oxygen or a carbonizing gas is then fed to the chamber and reacts with the susceptor to form compounds which disperse and dissolve in the zones. On cooling, a strong joint is formed. The susceptor may contain inner perforations and outer perforations to aid in distribution of heat.

Schroeder, J. E.↗

NASA NTRS1983

Material removal considerations for metal-ceramic abradable turbine seal systems

Possible interaction mechanisms between turbine blade tips and ceramic seal elements have been considered and preferred mechanism defined. The influence of porosity in the seal structure is qualitatively assessed and a preferred form determined. A dual-density plasma-sprayed ceramic seal system encompassing the desired characteristics is described and test results, including engine tests, are reported. Possible remedies to correct performance deficiencies are presented.

Clingman, D. L.↗

NASA NTRS1984

Ceramic composite liner material for gas turbine combustors

The application of ceramics to gas turbine combustor liners to reduce liner metal temperature was studied in an experiment in which yttria-stabilized zirconia plasma was sprayed on compliant metal substrates exposed to near stoichiometric combustion. The strain isolation pad materials chosen were Hoskins Alloy 875 and BRUNSLLOY 534 Fiber Metal of 0.25 and 0.38 cm thicknesses and 35 and 45 percent density levels. Combustor screening tests of all specimens showed no evidence of deterioration or failure. Specimens exposed to flame temperatures in excess of 2100 K were convectively or convective-transpiration cooled and were evaluated in a 10 cm sq flame tube at inlet air temperature of 533 K and pressure of 0.5 MPa. The results suggest the superiority of a system composed of the Hoskins Alloy 875 compliant pad with 0.25 cm thickness and 35 percent density coupled with a NiCrAlY bond coat and a 8 percent Y2O3-ZrO2 ceramic top coat of 0.19 cm thickness.

Ercegovic, D. B.↗

NASA NTRS1984

Sealing ceramic material in low melting point glass

A structured device placed in an aerated crucible to pack ceramics molding substance that is to be processed was designed. The structure is wrapped by sealing material made of pyrex glass and graphite foil or sheet with a weight attached on top of it. The crucible is made of carbon; the ceramics material to be treated through heat intervenient press process is molding substance consisting mainly of silicon nitride.

Moritoki, M.↗

NASA NTRS1984

Single-drop impact damage prediction for low density, coated ceramic materials

A technique utilizing finite element analysis, liquid impact kinematics, and momentum theory is described and compared to single-drop impact test data performed on various configurations of coated ceramic material. The method correlates well with test data and is useful in predicting the single-drop impact damage velocity threshold for low-density, coated ceramic materials.

Mustelier, D.↗

NASA NTRS1984

Microstructure and properties of ceramics

The history of research into the microstructure and properties of ceramic ware is discussed; methods of producing ceramics with particular characteristics are investigated. Bubbles, sintering, cracks, and electron microscopy are discussed.

Hamano, K.↗

NASA NTRS1984

Transformation toughened ceramics for the heavy duty diesel engine technology program

The objective of this program is to develop an advanced high temperature oxide structural ceramic for application to the heavy duty diesel engine. The approach is to employ transformation toughening by additions of ZrO.5HfO.5O2 solid solution to the oxide ceramics, mullite (2Al2O3S2SiO2) and alumina (Al2O3). The study is planned for three phases, each 12 months in duration. This report covers Phase 1. During this period, processing techniques were developed to incorporate the ZrO.5HfO.5O2 solid solution in the matrices while retaining the necessary metastable tetragonal phase. Modulus of rupture and of elasticity, coefficient of thermal expansion, fracture toughness by indent technique and thermal diffusivity of representative specimens were measured. In Phase 2, the process will be improved to provide higher mechanical strength and to define the techniques for scale up to component size. In Phase 3, full scale component prototypes will be fabri-]cated.

Musikant, S.↗

NASA NTRS1985

Experimental study of ceramic coated tip seals for turbojet engines

Ceramic gas-path seals were fabricated and successfully operated over 1000 cycles from flight idle to maximum power in a small turboshaft engine. The seals were fabricated by plasma spraying zirconia over a NiCoCrAlX bond boat on the Haynes 25 substrate. Coolant-side substrate temperatures and related engine parameters were recorded. Post-test inspection revealed mudflat surface cracking with penetration to the ceramic bond-coat interface.

Biesiadny, T. J.↗

NASA NTRS1985

Ribbon burner simulation of T-700 turbine shroud for ceramic lined seals research

Experimental and analytical studies were conducted to determine the acceptability of a ribbon-burner simulation of engine conditions for testing ceramic-lined turbine tip shrouds. The calculated values reveal that the ribbon burner establishes at least as harsh a thermal environment as is present at any time within the turbine shroud. Comparisons were made with ceramic components in a turboshaft engine.

Little, J. K.↗

NASA NTRS1983

Research study for gel precursors as glass and ceramic starting materials for space processing applications research

The development of techniques for the preparation of glass and ceramic starting materials that will result in homogeneous glasses or ceramic products when melted and cooled in a containerless environment is described. Metal-organic starting materials were used to make compounds or mixtures which were then decomposed by hydrolysis reactions to the corresponding oxides. The sodium tungstate system was chosen as a model for a glass with a relatively low melting temperature. The alkoxide tungstates also have interesting optical properties. For all the compositions studied, comparison samples were prepared from inorganic starting materials and submitted to the same analyses.

Downs, R. L.↗

NASA NTRS1984

Why ceramic engines?

Oil is still a problem for the U.S. and its allies. Transportation uses 61 percent of U.S. oil and its share is increasing, so more efficient technology should be concentrated there. Trucks' share of oil use is increasing because they are already much more efficient than autos. The primary truck opportunities are streamlining, more efficient engines, and shifting freight to railroads. More efficient engines are possible using ceramics to allow elimination of cooling systems and better use of waste exhaust heat. A 60 percent improvement seems possible if ceramics can be made tough enough and durable enough.

Stadler, H. L.↗

NASA NTRS1984

Ceramic component development for the AGT101 gas turbine engine

Under DOE/NASA sponsorship, a team is developing the AGT101, a highly efficient gas turbine engine for automotive application. The regenerated engine will operate at a maximum of 1370 C (2500 F) and 100,000 rpm, and will utilize a variety of Si3N4, SiC, lithium aluminum silicate and ceramic fiber insulation components. Engine design has been performed to consider the fabrication and material characteristics of these ceramic materials for both the static and rotating hot section components. Component fabrication has been performed, components have been screened in thermal and mechanical tests, and initial engine testing has been performed.

Carruthers, W. D.↗

NASA NTRS1985

High temperature metal and ceramic composites

The Materials Division at NASA Lewis is engaged in research and development efforts on behalf of fiber-reinforced composite materials that are lighter, stiffer, and more structurally reliable than conventional monolithic alloys and ceramics in applications that range from the cryogenic to the refractory. Attention is presently given to metal matrix composites, in which high performance depends on stiff, strong and thermally stable large diameter fibers, with chemically stable interfacial bonding and good coefficient of thermal expansion matching between fibers and matrices, and to ceramic matrix composites, in which intermediate strength interfacial bonds must allow cracks to propagate through the matrix only, while retaining good load transfer characteristics between fiber and matrix.

Signorelli, R. A.↗

NASA NTRS1985

Photoacoustic microscopy of ceramic turbine blades

Scanning photoacoustic microscopy (SPAM) is evaluated as a nondestructive technique for the detection of both surface and subsurface flaws in polycrystalline ceramics, such as those currently under consideration for the high temperature components of small vehicular and industrial gas turbine engines; the fracture strength of these brittle materials is controlled by small, 25-200 micron flaws. Attention is given to the correlation of SPAM-detected flaws with actual, fracture-controlling flaws in ceramic turbine blades.

Khandelwal, P. K.↗

NASA NTRS1986

Si3N4-Based Ceramic With Greater Hot Strength

Zyttrite-doped material outperforms MgO-doped material above 1,200 degrees C. New ceramic material produced by addition of 10 weight percent zyttrite (yttria-stabilized zirconia) to (silicon nitride) offers significantly-improved high-temperature properties (those of MgO-doped Si3N4 ceramic). Work also showed that controlled Si3N4 powder with 10 weight percent zyttrite, significant improvement in room-temperature strength achieved. Variety of high-temperature structural applications are silicon nitride and silicon carbide. Potential for use in aircraft and automobile engines and in electric-power generating systems. Improved properties strongly suggest that the 10-weight percent zyttrite/Si3N4 material has strong potential for high-temperature applications.

Dutta, S.↗