Preparation and evaluation of silicon nitride matrices for silicon nitride-SiC fiber composites. M. S. Thesis Final Technical Report

Technical Report · Mon Feb 01 04:00:00 EST 1988

OSTI ID:5651095

Axelson, S R

Continuous silicon carbide (SiC) fiber was added to three types of silicon nitride (Si{sub 3}N{sub 4}) matrices. Efforts were aimed at producing a dense Si3N4 matrix from reaction-bonded silicon nitride (RBSN) by hot-isostatic-pressing (HIP) and pressureless sintering, and from Si{sub 3}N{sub 4} powder by hot-pressing. The sintering additives utilized were chosen to allow for densification, while not causing severe degradation of the fiber. The ceramic microstructures were evaluated using scanning optical microscopy. Vickers indentation was used to determine the microhardness and fracture toughness values of the matrices. The RBSN matrices in this study did not reach more than 80 percent of theoretical density after sintering at various temperatures, pressures, and additive levels. Hot-pressing Si{sub 3}N{sub 4} powder produced the highest density matrices; hardness and toughness values were within an order of magnitude of the best literature values. The best sintering aid composition chosen included Y{sub 2}O{sub 3}, SiO{sub 2}, and Al{sub 2}O{sub 3} or AlN. Photomicrographs demonstrate a significant reduction of fiber attack by this additive composition.

• Research Organization: Alfred Univ., NY (USA)
• OSTI ID: 5651095
• Report Number(s): N-89-23678; NASA-CR--184798; NAS--1.26:184798
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ADDITIVES
ALUMINIUM COMPOUNDS
ALUMINIUM NITRIDES
ALUMINIUM OXIDES
BONDING
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
COMPOSITE MATERIALS
CRYSTAL STRUCTURE
DOCUMENT TYPES
FABRICATION
FAILURES
FIBERS
FRACTURES
HARDNESS
HOT PRESSING
JOINING
MATERIALS
MATERIALS WORKING
MATRIX MATERIALS
MECHANICAL PROPERTIES
MICROHARDNESS
MICROSTRUCTURE
MINERALS
NITRIDES
NITROGEN COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PNICTIDES
PRESSING
PROGRESS REPORT
SILICA
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
SILICON OXIDES
SINTERING
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES