Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

This is a second Triennial Conference on the physical, chemical, and mechanical properties of materials, interpreted to mean
simple and complex inorganic solids, i.e., metals, semiconductors, and mineral of technological and environmental significance.
DTIC
Alloys; Minerals; Semiconductors (Materials); Metals
20000064094 NASA Glenn Research Center, Cleveland, OH USA
Effects of Melt Convection and Solid Transport on Macrosegregation and Grain Structure in Equiaxed Al-Cu Alloys
Rerko, Rodney S., Iowa Univ., USA; deGroh, Henry C., III, NASA Glenn Research Center, USA; Beckermann, Christoph, Iowa
Univ., USA; May 2000; 118p; In English
Contract(s)/Grant(s): RTOP 101-13-0A
Report No.(s): NASA/TM-2000-210020; E-12217; NAS 1.15:210020; No Copyright; Avail: CASI; A06, Hardcopy; A02, Microfiche
Macrosegregation in metal casting can be caused by thermal and solutal melt convection, and the transport of unattached solid
crystals resulting from nucleation in the bulk liquid or dendrite fragmentation. to develop a comprehensive numerical model for
the casting of alloys, an experimental study has been conducted to generate benchmark data with which such a solidification model
could be tested. The objectives were: (1) experimentally study the effects of solid transport and thermosolutal convection on
macrosegregation and grain size; and (2) provide a complete set of boundary conditions temperature data, segregation data, and
grain size data - to validate numerical models. Through the control of end cooling and side wall heating, radial temperature gradients
in the sample and furnace were minimized. Thus the vertical crucible wall was adiabatic. Samples at room temperature were
24 cc and 95 mm long. The alloys used were Al-1 wt. pct. Cu, and Al- 10 wt. pct. Cu; the starting point for solidification was
isothermal at 710 and 685 C respectively. to induce an equiaxed structure various amounts of the grain refiner TiB2 were added.
Samples were either cooled from the top, or the bottom. Several trends in the data stand out. In attempting to model these experiments,
concentrating on these trends or differences may be beneficial.
Author
Melts (Crystal Growth); Convection; Solidification; Transport Properties; Aluminum Alloys; Copper; Experimentation; Grain
Size; Temperature Gradients; Free Convection; Fragmentation
20000064095 Case Western Reserve Univ., Cleveland, OH USA
Thermophysical Properties of GRCop-84 Final Report
Ellis, David L., Case Western Reserve Univ., USA; Keller, Dennis J., RealWorld Quality Systems, Inc., USA; June 2000; 22p;
In English
Contract(s)/Grant(s): NAS3-463; RTOP 242-23-54
Report No.(s): NASA/CR-2000-210055; E-12257; NAS 1.26:210055; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche
The thermophysical properties and electrical resistivity of GRCop-84 (Cu - 8 at.% Cr-4 at.% Nb) were measured from cryogenic
temperatures to near its melting point. The data were analyzed using weighted regression to determine the properties as a
function of temperature and assign appropriate confidence intervals. The results showed that the thermal expansion of GRCop-84
was significantly lower than NARloy-Z (Cu-3 wt. % Ag-0.5 wt. % Zr), the currently used thrust cell liner material. The lower
thermal expansion is expected to translate into lower thermally induced stresses and increases in thrust cell liner lives between
2X and 41X over NARloy-Z. The somewhat lower thermal conductivity of GRCop-84 can be offset by redesigning the liners to
utilize its much greater mechanical properties. Optimized designs are not expected to suffer from the lower thermal conductivity.
Electrical resistivity data, while not central to the primary application, show that GRCop-84 has potential for applications where
a combination of good electrical conductivity and strength is required.
Author
Copper Alloys; Chromium Alloys; Thermophysical Properties; Electrical Resistivity; Measure and Integration; Cryogenic Temperature
20000064902 NASA Lewis Research Center, Cleveland, OH USA
Thermal Studies of New Precursors to Indium-tin Oxides for Use as Sensor Materials in the Detection of NO(x)
Goldsby, J. C., NASA Lewis Research Center, USA; Kacik, T., NASA Lewis Research Center, USA; Hockensmith, C. M.; Thermochimica
Acta; 1999; ISSN 0040-6031; Volume 340-1, pp. 315-322; In English; Copyright; Avail: Issuing Activity
Control of combustion product emissions in both sub and super-sonic jet engines can be facilitated by measurement of NO(x)
levels with metal oxide sensors, In2O3, metal-doped SnO2, and SnO, (as well as other materials) show resistivity changes in the
presence of NO(x), but often their sensitivity, stability, and selectivity are low. This study was designed to develop new synthetic
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