Silicon nitride ceramic matrix for CMCs from silane derived Si powders and preceramic polymers

Book · Sun Oct 01 04:00:00 EDT 1995

OSTI ID:100545

Rhine, W E; Lightfoot, A; Seyferth, D; Haggerty, J S ^[1]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States)

Si powders synthesized by the laser pyrolysis of silane can be nitrided at 1,200--1,250 C, producing an improved reaction bonded silicon nitride. This RBSN is a potential matrix for composites since it can be formed at temperatures which do not degrade the strengths of commercially available amorphous ceramic fibers. However, the density of the RBSN matrix has been limited to about 75% using the silane-derived Si powder. Combining Si powders and preceramic polymers offers an approach for increasing the density and mechanical properties of the reaction-formed Si{sub 3}N{sub 4} matrix. The incorporation of polysilazanes inhibited the nitridation oat 1,250 C, but samples could be effectively nitrided at 1,400 C. These higher nitriding temperatures are compatible with SCS-6 and other low-oxygen, crystalline SiC fibers which can be used as reinforcements for ceramic composites.

• OSTI ID: 100545
• Report Number(s): CONF-941144--; ISBN 1-55899-266-9
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BULK DENSITY
CHEMICAL REACTION KINETICS
EXPERIMENTAL DATA
FABRICATION
NITRIDATION
ORGANIC SILICON COMPOUNDS
PHASE STUDIES
PRESSING
SILICON
SILICON NITRIDES
SURFACE AREA
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION