NASA Scientific and Technical Aerospace Reports

systems, solid rocket motor nozzles, space (manned missions and planetary entry probes). Ablation mechanisms. Ablation
material testing. Ablative material testing.
Derived from text
Ablative Materials; Solid Propellant Rocket Engines; Nozzles; Materials Tests
20040046917 NASA Langley Research Center, Hampton, VA, USA, National Inst. of Aerospace Research, Hampton, VA,
USA
Constitutive Modeling of Piezoelectric Polymer Composites
Odegard, Gregory M.; Gates, Tom, Technical Monitor; December 2003; 33 pp.; In English
Contract(s)/Grant(s): NCC1-02043; 762-30-51-03
Report No.(s): NASA/CR-2003-212681; NIA-2003-10; No Copyright; Avail: CASI; A03, Hardcopy
A new modeling approach is proposed for predicting the bulk electromechanical properties of piezoelectric composites.
The proposed model offers the same level of convenience as the well-known Mori-Tanaka method. In addition, it is shown
to yield predicted properties that are, in most cases, more accurate or equally as accurate as the Mori-Tanaka scheme. In
particular, the proposed method is used to determine the electromechanical properties of four piezoelectric polymer composite
materials as a function of inclusion volume fraction. The predicted properties are compared to those calculated using the
Mori-Tanaka and finite element methods.
Author
Mathematical Models; Piezoelectricity; Models
20040046963 Lawrence Livermore National Lab., Livermore, CA
Pyrochlore-Rich Titanate Ceramics for the Immobilization of Plutonium: Redox Effects on Phase Equilibria in
Cerium- and Thorium- Substituted Analogs
Ryerson, F. J.; Ebbinghaus, B.; May 25, 2000; 56 pp.; In English
Report No.(s): DE2004-15005705; UCRL-ID-139092; No Copyright; Avail: Department of Energy Information Bridge
Three compositions representing plutonium-free analogs of a proposed Ca-Ti-Gd-Hf- U-PU oxide ceramic for the
immobilization of plutonium were equilibrated at 1 atm, 1350 degrees C over a range of oxygen fugacities between air and
that equivalent to the iron-wustite buffer. The cerium analog replaces Pu on a mole-per-mole basic with Ce; the thorium analog
replaces Pu with Th. A third material has 10 wt% Al2O3 added to the cerium analog to encourage the formation of a Hf-analog
of, CaHfTi207, zirconolite, which is referred to as hafnolite. The predominant phase produced in each formulation under all
conditions is pyrochlore, A2T207, where the T site is filled by Ti, and Ca, the lanthanides, Hf, U and Pu are accommodated
on the A-site. Other lanthanide and uranium-bearing phases encountered include brannerite (UTi206), hafnolite (CaHfTi207),
perovskite (CaTiO3) and a calcium-lanthanide alurninotitanate with nominal stoichiometry (CaJM)Ti2Al9O19, where Ln is
a lanthanide.
NTIS
Ceramics; Plutonium; Radioactive Wastes
20040046964 Lawrence Livermore National Lab., Livermore, CA
Saturation of Impurity-Rich Phases in a Cerium-Substituted Pyrochlore-Rich Titanate Ceramic: Part 1. Experimental
Results
Ryerson, F. J.; Ebbinghaus, B.; Kirkorian, O.; VanKonynenburg, R.; May 25, 2000; 96 pp.; In English
Report No.(s): DE2004-15005706; UCRL-ID-139093-P1; No Copyright; Avail: Department of Energy Information Bridge
The saturation of impurity-rich accessory phases in a Cc-analog baseline ceramic formulation for the immobilization of
excess plutonium has been tested by synthesizing an impurity-rich baseline compositions at 1300 degrees C 1350 degrees C
and 1400 degrees C in air. Impurity oxides are added at the 10 wt% level. The resulting phases assemblages are typically rich
in pyrochlore, Hf-zirconolite (hafnolite), brannerite and rutile, but in many instances also contain an accessory mineral
enriched in the impurity oxide. The concentration of that oxide in coexisting pyrochlore sets the saturation limit for solid
solution of the component in question. In most cases, the accessory phase does not contain significant amounts of Ce, Gd or
U. Exceptions are the stabilization of a Ca-lanthanide phosphate and a phosphate glass when P2O5 is added to the formulation.
P2O3 addition is also very effective in reducing the modal amount of pyrochlore in the form relative to brannerite. Addition
of the sodium-aluminosilicate, NaAISiO4, also results in the formation of a grain bounday melt at run conditions, but the fate
of this phase on cooling is not well determined. At temperatures above 1300degreesC, addition of 10 wt percent Fe2O3 also
leads to melting. Substitution of cations of different valences can also be associated with model-dependent changes in the
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