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Creep and Rupture Strength of an Advanced CVD SiC FiberIn the as-produced condition the room temperature strength (approx. 6 GPa) of Textron Specialty Materials' 50 microns CVD SiC fiber represents the highest value thus far obtained for commercially produced polycrystalline SiC fibers. To understand whether this strength can be maintained after composite processing conditions, high temperature studies were performed on the effects of time, stress, and environment on 1400 deg. C tensile creep strain and stress rupture on as-produced, chemically vapor deposited SiC fibers. Creep strain results were consistent, allowing an evaluation of time and stress effects. Test environment had no influence on creep strain but I hour annealing at 1600 deg. C in argon gas significantly reduced the total creep strain and increased the stress dependence. This is attributed to changes in the free carbon morphology and its distribution within the CVD SiC fiber. For the as-produced and annealed fibers, strength at 1400 deg. C was found to decrease from a fast fracture value of 2 GPa to a 100-hr rupture strength value of 0. 8 GPa. In addition a loss of fast fracture strength from 6 GPa is attributed to thermally induced changes in the outer carbon coating and microstructure. Scatter in rupture times made a definitive analysis of environmental and annealing effects on creep strength difficult.
Document ID
19970017406
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Goldsby, J. C.
(NASA Lewis Research Center Cleveland, OH United States)
Yun, H. M.
(Cleveland State Univ. Cleveland, OH United States)
DiCarlo, J. A.
(NASA Lewis Research Center Cleveland, OH United States)
Date Acquired
September 6, 2013
Publication Date
April 1, 1997
Subject Category
Nonmetallic Materials
Report/Patent Number
NASA-TM-107368
NAS 1.15:107368
E-10536
Accession Number
97N19683
Funding Number(s)
PROJECT: RTOP 505-63-12
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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