NASA Scientific and Technical Aerospace Reports

Vane subelements were fabricated from a silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composite and
were coated with an environmental barrier coating (EBC). A test configuration for the vanes in a gas turbine environment was
designed and fabricated. Prior to testing, finite element analyses were performed to predict the temperatures and stress
conditions present in vane during rig testing. This paper discusses the test configuration, the finite element analysis predictions,
and results of the vane testing.
Author
Ceramic Matrix Composites; Guide Vanes; Silicon Carbides; Ceramic Fibers; Composite Structures; Gas Turbines;
Temperature; Tensile Stress
20040120867 NASA Glenn Research Center, Cleveland, OH, USA
Stressed Oxidation Life Prediction for C/SiC Composites
Levine, Stanley R.; [2004]; 6 pp.; In English; Fifth International Conference on High Temperature Ceramic Matrix
Composities (HTCMC-5), 12-16 Sep. 2004, Seattle, WA, USA
Contract(s)/Grant(s): WBS 22-794-20-65; No Copyright; Avail: CASI; A02, Hardcopy
The residual strength and life of C/SiC is dominated by carbon interface and fiber oxidation if seal coat and matrix cracks
are open to allow oxygen ingress. Crack opening is determined by the combination of thermal, mechanical and thermal
expansion mismatch induced stresses. When cracks are open, life can be predicted by simple oxidation based models with
reaction controlled kinetics at low temperature, and by gas phase diffusion controlled kinetics at high temperatures. Key life
governing variables in these models include temperature, stress, initial strength, oxygen partial pressure, and total pressure.
These models are described in this paper.
Author
Oxidation; Oxygen; Cracks; Life (Durability); Carbon Fibers; Silicon Carbides; Models
20040120893 Massachusetts Inst. of Tech., Cambridge, MA, USA
Use of Advanced Composites in Maglev Guideway System
Buyukozturk, O.; Au, C.; Mar. 2003; 82 pp.; In English
Report No.(s): PB2004-106418; No Copyright; Avail: CASI; A05, Hardcopy
In 1998, the Federal Transit Administration (FTA) initiated the Urban Magnetic Levitation (Maglev) Transit Technology
Development Program to refine existing and to develop new technologies that will lead to a deployable US urban Maglev
system with advanced characteristics, which have life-cycle cost and performance benefits. One of the key elements of the
urban Maglev systems is the guideway, which represents 40-60% of the system cost. This feasibility study examined the
suitability of the use of advanced Fiber Reinforced Polymer (FRP) composites for the construction of Maglev guideways. The
guideway system performance criteria have stringent requirements with respect to ride quality, aesthetics, behavior under
extreme environmental loading, durability, construction, maintenance, and system scalability. These many criteria have led
collectively to a guideway structure that is capable of delivering high structural and durability performance with modularity
and optimization capability characteristics over the 75 year life-cycle of the system.
NTIS
Composite Materials; Magnetic Suspension; Automated Guideway Transit Vehicles
20040120921 Lawrence Livermore National Lab., Livermore, CA
Development of Direct and Optical Polarized Nuclear Magnetic Resonance (NMR) Methods for Characterization and
Engineering of Mesophased Molecular Structures
Maxwell, R.; Baumann, T.; Taylor, B.; Jan. 2002; In English
Report No.(s): DE2003-15005321; UCRL-ID-147034; No Copyright; Avail: National Technical Information Service (NTIS)
The development of NMR methods for the characterization of structure and dynamics in mesophase composite systems
was originally proposed in this LDRD. Mesophase systems are organic/inorganic hybrid materials whose size and motional
properties span the definition of liquids and solids, such as highly viscous gels or colloidal suspensions. They are often
composite, ill defined, macromolecular structures that prove difficult to characterize. Mesophase materials are of broad
scientific and programmatic interest and include composite load bearing foams, aerogels, optical coatings, silicate oligomers,
porous heterogeneous catalysts, and nanostructured materials such as semiconductor quantum dot superlattices. Since
mesophased materials and precursors generally lack long-range order they have proven to be difficult to characterize beyond
local, shortrange order. NMR methods are optimal for such a task since NMR observables are sensitive to wide ranges of
length (0-30(angstrom)) and time (10(sup -9)-10(sup 0)sec) scales. We have developed a suit of NMR methods to measure
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