Oxidation effects on the mechanical properties of SiC fiber-reinforced reaction-bonded silicon nitride matrix composites

Technical Report · Wed Nov 01 00:00:00 EST 1989

OSTI ID:7249580

Bhatt, R T

The room temperature mechanical properties of SiC fiber reinforced reaction bonded silicon nitride composites were measured after 100 hrs exposure at temperatures to 1400 C in nitrogen and oxygen environments. The composites consisted of approx. 30 vol percent uniaxially aligned 142 micron diameter SiC fibers in a reaction bonded Si3N4 matrix. The results indicate that composites heat treated in a nitrogen environment at temperatures to 1400 C showed deformation and fracture behavior equivalent to that of the as-fabricated composites. Also, the composites heat treated in an oxidizing environment beyond 400 C yielded significantly lower tensile strength values. Specifically in the temperature range from 600 to 1000 C, composites retained approx. 40 percent of their as-fabricated strength, and those heat treated in the temperatures from 1200 to 1400 C retained 70 percent. Nonetheless, for all oxygen heat treatment conditions, composite specimens displayed strain capability beyond the matrix fracture stress; a typical behavior of a tough composite.

• Research Organization: National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center
• OSTI ID: 7249580
• Report Number(s): N-90-14287; NASA-TM-102360; E-5074; NAS-1.15:102360; AVSCOM-TR-89-C-018
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
MECHANICAL PROPERTIES
OXIDATION
SILICON CARBIDES
SILICON NITRIDES
CREEP
DEFORMATION
FIBERS
MATRIX MATERIALS
MICROSTRUCTURE
TEMPERATURE EFFECTS
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
MATERIALS
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
SILICON COMPOUNDS
360604* - Materials- Corrosion
Erosion
& Degradation