Characterization and control of the fiber-matrix interface in ceramic matrix composites
Fiber-reinforced SiC composites fabricated by thermal-gradient forced-flow chemical-vapor infiltration (FCVI) have exhibited both composite (toughened) and brittle behavior during mechanical property evaluation. Detailed analysis of the fiber-matrix interface revealed that a silica layer on the surface of Nicalon Si-C-O fibers tightly bonds the fiber to the matrix. The strongly bonded fiber and matrix, combined with the reduction in the strength of the fibers that occurs during processing, resulted in the observed brittle behavior. The mechanical behavior of Nicalon/SiC composites has been improved by applying thin coatings (silicon carbide, boron, boron nitride, molybdenum, carbon) to the fibers, prior to densification, to control the interfacial bond. Varying degrees of bonding have been achieved with different coating materials and film thicknesses. Fiber-matrix bond strengths have been quantitatively evaluated using an indentation method and a simple tensile test. The effects of bonding and friction on the mechanical behavior of this composite system have been investigated. 167 refs., 59 figs., 18 tabs.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- DOE/FE
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6855809
- Report Number(s):
- ORNL/TM-11039; ON: DE91000922
- Country of Publication:
- United States
- Language:
- English
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36 MATERIALS SCIENCE
COMPOSITE MATERIALS
MECHANICAL PROPERTIES
PROTECTIVE COATINGS
DEPOSITION
SILICON CARBIDES
BORON
BORON NITRIDES
CERAMICS
COAL
CONVERSION
FABRICATION
FRICTION
INTERFACES
MICROSTRUCTURE
MOLYBDENUM
REINFORCED MATERIALS
TENSILE PROPERTIES
BORON COMPOUNDS
CARBIDES
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
COATINGS
CRYSTAL STRUCTURE
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
MATERIALS
METALS
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
SEMIMETALS
SILICON COMPOUNDS
TRANSITION ELEMENTS
010400* - Coal
Lignite
& Peat- Processing
014000 - Coal
Lignite
& Peat- Combustion
360603 - Materials- Properties
360602 - Other Materials- Structure & Phase Studies