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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Development of dispersion-strengthened Ni-Cr-ThO2 alloys for the space shuttle thermal protection system.

An improved manufacturing process has been developed for TD-NiCr that provides sheet of improved quality, better gage control, and reproducible properties. A standard manufacturing process has been developed for the alternate alloy, DS-NiCr, produced by pack-chromizing Ni-2ThO2 sheet. Extension of forming and joining technology for TD-NiCr is in process. Formability criteria are being established for basic sheet forming processes related to the manufacture of Shuttle TPS panels. They include brake forming, corrugation forming, joggling, dimpling, and beading. Joining processes applicable to TPS panels are being optimized with emphasis on establishment of joint efficiencies. Resistance spot welding (fusion and solid state), resistance seam welding, solid-state diffusion welding, and brazing are included in the joining programs. Development of improved manufacturing technology for TD-NiCr fasteners is also being accomplished. Mechanical and physical properties of TD-NiCr are being characterized to provide design-allowable data.

Blankenship, C. P.↗
NASA NTRS1972

Occurrence of diopside and Cr-Zr-armalcolite on the moon.

Petrographic and electron-microprobe examination of the sample of 1 to 2 mm fines, Apollo 14166,6, has revealed a fragment with the unique lunar mineralogy of plagioclase, olivine, diopside, a Ti-Fe-Zr phase, and a trace of ilminite. The second occurrence of diopside is reported together with the third occurrence of a recently identified Ti-Fe-Zr phase. Microprobe analyses of the principal phases of the fragment studied are presented in a table. The relatively pure diopside analyses reported represent the most Mg-rich calcic pyroxene found in lunar material.

Steele, I. M.↗
NASA NTRS1971

Development of dispersion strengthened nickel-chromium alloy (Ni-Cr-Th-O2) sheet for space shuttle vehicles, part 1

A dispersion-strengthened alloy, TD nickel chromium (TDNiCr) is being developed for use on the thermal protection system of the space shuttle at temperatures up to 1204 C(2200 F). Manufacturing processes were developed for the fabrication of sheet and foil to specifications. The addition of aluminum to the basic TDNiCr composition provides outstanding oxidation resistance up to 1260 C(2300 F); aluminum levels of 2 to 4% are considered optimum for space shuttle application.

Klingler, L. J.↗
NASA NTRS1974

The effect of yttrium and thorium on the oxidation behavior of Ni-Cr-Al alloys

The effect of quaternary additions of 0.5% Y, 0.5 and 1.0% Th to a base alloy of Ni-10CR-5Al on the oxidation behavior and mechanism was studied during oxidation in air over the range of 1000 to 1200 C. The presence of yttrium decreased the oxidation kinetics slightly, whereas, the addition of thorium caused a slight increase. Oxide scale adherence was markedly improved by the addition of the quaternary elements. Although a number of oxides formed on yttrium containing alloys, quantitative X-ray diffraction clearly showed that the rate-controlling step was the diffusion of aluminum through short circuit paths in a thin layer of alumina that formed parabolically with time. Although the scale adherence of the yttrium containing alloy was considerably better than the base alloys, spalling did occur that was attributed to the formation of the voluminous YAG particles which grew in a mushroom-like manner, lifting the protective scale off the subrate locally. The YAG particles formed primarily at grain boundaries in the substrate in which the yttrium originally existed as YNi9.

Kumar, A.↗
NASA NTRS1973

Cyclic and isothermal oxidation behavior on some Ni-Cr alloys

It is shown experimentally that 3 wt.% Si and 3 wt.% Mn additions can substantially improve the oxidation resistance of Ni-20Cr under both isothermal and cyclic conditions at 1100 and 1200 C. This is especially true in cyclic oxidation. In all cases, Si offers a greater improvement than Mn; however, the advantage of Si is substantial only during cyclic oxidation at 1200 C. The Si additions which lead to alloys of improved oxidation resistance suppress the formation of NiO and NiCr2O4 even under the most severe test conditions. The mechanism of improvement afforded by Mn appears to be the formation of MnCr2O4 at the expense of NiO and NiCr2O4.

Lowell, C. E.↗
NASA NTRS1974

NASA CR-2120 - Summary of nondestructive testing theory and practice

This is a familiarization report of nondestructive testing (ndt) prepared by staff of the Battelle Columbus Laboratories on a NASA contract. There is a short introduction, a chapter on applicability of ndt which is illustrated with examples of typical defects and includes tables comparing the characteristics, interrelationships, and costs of the different techniques. There are chapters dealing with penetrants, magnetic particle radiography, ultrasonics, and eddy currents. New techniques are described.

Meister, R. P.↗
NASA NTRS1975

Optimization of an oxide dispersion strengthened Ni-Cr-Al alloy for gas turbine engine vanes

The investigation was carried out to determine the optimum alloy within the Ni-16Cr-Al-Y2O3 system for use as a vane material in advanced aircraft gas turbine engines. Six alloys containing nominally 4%, 5% and 6% Al with Y2O3 levels of 0.8% and 1.2% were prepared by mechanical attrition. Six small-scale, rectangular extrusions were produced from each powder lot for property evaluation. The approximate temperatures for incipient melting were found to be 1658 K (2525 F), 1644 K (2500 F) and 1630 K (2475 F) for the 4%, 5% and 6% aluminum levels, respectively. With the exception of longitudinal crystallographic texture, the eight extrusions selected for extensive evaluation either exceeded or were close to mechanical property goals. Major differences between the alloys became apparent during dynamic oxidation testing, and in particular during the 1366 K (2000 F)/500 hour Mach 1 tests carried out by NASA-Lewis. An aluminum level of 4.75% was subsequently judged to be optimum based on considerations of dynamic oxidation resistance, susceptibility to thermal fatigue cracking and melting point.

Klarstrom, D. L.↗
NASA NTRS1976

Fixed charge in Cr-metallized MOS capacitors

It is pointed out that the reported measurements are useful in a study of interface charge distributions. Measurements of surface-state density at the SiO2 interface given information concerning the effect of the layer thickness on the flat-band interface charge. Other measurements provide data for a determination of the silicon-silica flat-band interface charge, the metal-silica interface charge, and the difference in barrier energies at the interfaces. Measurements of Fowler-Nordheim currents as a function of oxide thickness can be used for the determination of charge distribution in the area next to the metal-silica interface. The investigation shows that the silicon-silica interface is independent of thickness down to thicknesses as low as 40 A.

Lewicki, G.↗
NASA NTRS1976

Solubility of Cr, Ti, and Al in co-existing olivine, spinel, and liquid at 1 atm

The partitioning of chromium between olivines, spinels and silicate liquids was studied as a function of temperature, oxygen fugacity, and cooling rate between 1175 and 1300 C and redox states near the Fe-FeO buffer. It is found that the weight ratio of Cr2O3 in olivine to that in the liquid increases slightly as oxygen fugacity decreases, but the effect is very small. The cooling experiments showed that the Cr2O3 content does not re-equilibrate with cooling.

Akella, J.↗