Issue 10 Volume 41 May 16, 2003

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COMPOSITE MATERIALS
Includes physical, chemical, and mechanical properties of laminates and other composite materials.
20030032272 NASA Glenn Research Center, Cleveland, OH, USA
Effect of Environment on Stress-Rupture Behavior of a Carbon Fiber-Reinforced Silicon Carbide (C/SiC) Ceramic
Matrix Composite
Verrilli, Michael J.; Opila, Elizabeth J.; Calomino, Anthony; Kiser, J. Douglas; November 26, 2002; 25 pp.; In English;
Original contains black and white illustrations
Contract(s)/Grant(s): WBS 22-708-73-13; Copyright; Avail: CASI; A03, Hardcopy
Stress-rupture tests were conducted in air, vacuum, and steam-containing environments to identify the failure modes and
degradation mechanisms of a carbon fiber-reinforced silicon carbide (C/SiC) composite at two temperatures, 600 and 1200 C.
Stress-rupture lives in air and steam containing environments (50 - 80\% steam with argon) are similar for a composite stress
of 69 MPa at 1200 C. Lives of specimens tested in a 20\% steam/argon environment were about twice as long. For tests
conducted at 600 C, composite life in 20\% steam/argon was 20 times longer than life in air. Thermogravimetric analysis of
the carbon fibers was conducted under similar conditions to the stress-rupture tests. The oxidation rate of the fibers in the
various environments correlated with the composite stress-rupture lives. Examination of the failed specimens indicated that
oxidation of the carbon fibers was the primary damage mode for specimens tested in air and steam environments at both
temperatures.
Author
Ceramic Matrix Composites; Silicon Carbides; Creep Rupture Strength; Environment Effects; High Temperature Tests
20030032273 NASA Glenn Research Center, Cleveland, OH, USA
Additive Effects on Si3N4 Oxidation/Volatilization in Water Vapor
Opila, Elizabeth J.; Robinson, R. Craig; Fox, Dennis S.; Wenglarz, Richard A.; Ferber, Mattison K.; [2002]; 38 pp.; In
English; Original contains black and white illustrations; Copyright; Avail: CASI; A03, Hardcopy
Two commercially available additive-containing silicon nitride materials were exposed in four environments which range
in severity from dry oxygen at 1 atm pressure, and low gas velocity to an actual turbine engine. Oxidation and volatilization
kinetics were monitored at temperatures ranging from 1066 to 1400 C. The main purpose of this paper is to examine the
surface oxide morphology resulting from the exposures. It was found that the material surface was enriched in rare earth
silicate phases in combustion environments when compared to the oxides formed on materials exposed in dry oxygen.
However, the in situ formation of rare earth disilicate phases offered little additional protection from the volatilization of silica
observed in combustion environments. It was concluded that externally applied environmental barrier coatings are needed to
protect additive-containing silicon nitride materials from volatilization reactions in combustion environments. Introduction
Si3N4 is proposed for use as components, such as vanes, in turbine applications. Tens of thousands of hours of life are needed
for both land-based turbines and aeropropulsion applications. Additive-containing SisN4 materials are
Author
Silicon Nitrides; Oxidation; Turbine Engines; Surface Distortion; Reaction Kinetics; Vaporizing
20030032275 NASA Glenn Research Center, Cleveland, OH, USA
Impact Resistance of Lightweight Hybrid Structures for Gas Turbine Engine Fan Containment Applications
Hebsur, Mohan G.; Noebe, Ronald D.; Revilock, Duane M.; [2003]; 38 pp.; In English; Original contains color illustrations
Contract(s)/Grant(s): 22-708-24-05; No Copyright; Avail: CASI; A03, Hardcopy
The ballistic impact resistance of hybrid composite sandwich structures was evaluated with the ultimate goal of
developing new materials or structures for potential gas turbine engine fan containment applications. The sandwich structures
investigated consisted of GLARE-5 laminates as face sheets with lightweight cellular metallic materials such as honeycomb,
foam, and lattice block as a core material. The impact resistance of these hybrid sandwich structures was compared to
GLARE-5 laminates and 2024-T3 Al sheet, which were tested as a function of areal weight (material thickness). The
GLARE-5 laminates exhibited comparable impact properties to that of 2024-T3 Al at low areal weights, even though there
were significant differences in the static tensile properties of these materials. The GLARE-5, however, did have a greater
ballistic limit than straight aluminum sheet at higher areal weights. Furthermore, there is up to a 25\% advantage in ballistic
limit for the GLARE-5/foam sandwich structures compared to straight 2024-T3 Al. But no advantage in ballistic limit was
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