Heat treatment effects on the tensile properties and microstructures of a SiC/RBSN composite in nitrogen
The room-temperature tensile properties and constituent microstructures of a unidirectionally reinforced SiC/reaction bonded silicon nitride (RBSN) composite have been investigated after heat treatments at 1400, 1600, or 1800 C in nitrogen for up to 100 hr. The composite consisted of approximately 24 vol% of aligned 140 micron diameter, continuous length, chemically vapor deposited SiC fibers in an approximately 40% porous silicon nitride matrix. The composites heat treated at 1400 C for up to 100 hr showed elastic modulus, first matrix cracking strength, and ultimate tensile strength values similar to those of the as-fabricated composites, but those heat treated for 1 hr beyond this temperature displayed losses in all three properties. Recrystallization of the SiC fibers, reaction between the carbon-rich interface coating on the fibers and the RBSN matrix, and dissociation of the RBSN matrix are the reasons for the loss of mechanical properties.
- Research Organization:
- National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center
- OSTI ID:
- 135412
- Report Number(s):
- N--96-12020; NASA-TM--106621; NAS--1.15:106621; E--8909; ARL-TR--878; CONF-9407200--; CNN: RTOP 505-63-12
- Country of Publication:
- United States
- Language:
- English
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