Synthesis, characterization, and fabrication of silicon carbide structural ceramics. [SiC-TiC-BN]

Conference · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6651072

Wei, G C; Morgan, C S; Kennedy, C R; Johnson, D R

Five processes of SiC powder synthesis were investigated: chemical vapor decomposition, high-temperature rotary-furnace reactions, gel synthesis of precursors followed by carbothermic reduction, pyrolysis of polymeric precursors, and the Acheson process. Exploratory powder synthesis experiments were conducted on the gel process involving gelation of colloidal silica and petroleum pitch in toluene, or polymerization of methyltrimethoxysilane and resin in alcohol. The ..beta..-SiC powders synthesized by these gel processes have specific surface areas (SSA) exceeding 20 m/sup 2//g and round or polyhedral particle shape. These materials have excellent pressure sintering capability. SiC powder made by the rotary-furnace process consists of fine ..beta..-SiC particles with a round morphology and about 10 m/sup 2//g SSA. The rotary-furnace SiC powders with BN dopants were hot pressed to 95% dense. A commercial polycarbosilane prepared from dechlorination and polymerization reactions of vinyl and chloromethyl silanes was pyrolyzed and hot pressed without BN to 79% dense. In terms of pressureless sintering, the best result (96+% dense) is obtained with the Starck-SiC powder by doping with 0.8 wt % B and 2 wt % phenolic resin and sintering under argon in a graphite furnace for 2 h at 2050/sup 0/C. An SiC-TiC-BN composite was hot pressed to 97+% dense with an indentation toughness nearly double that of sintered ..beta..-SiC. 10 figures, 6 tables.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 6651072
• Report Number(s): CONF-821145-2; ON: DE83003281
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360301 -- Composite Materials-- Preparation & Fabrication-- (-1987)
BORON COMPOUNDS
BORON NITRIDES
CARBIDES
CARBON COMPOUNDS
COLLOIDS
COMPOSITE MATERIALS
CRYSTAL STRUCTURE
DIAGRAMS
DISPERSIONS
ELECTRON MICROSCOPY
FABRICATION
FLOWSHEETS
FRACTURE PROPERTIES
GELS
HOT PRESSING
MATERIALS
MATERIALS WORKING
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
POWDERS
PRESSING
SILICON CARBIDES
SILICON COMPOUNDS
SINTERING
SURFACE AREA
SURFACE PROPERTIES
SYNTHESIS
TITANIUM CARBIDES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS