Strength of SiC- and Si-N-C-ceramic fibers exposed to high-temperature gaseous environments

Conference · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5854775

Moorhead, A J; Kim, Hyoun-Ee

The effects of exposures to high-temperature gaseous environments on the strengths of Nicalon SiC fiber and HPZ Si-N-C fiber were investigated. The exposure conditions included: (1) Ar with various P{sub O}{sub 2} at 1000{degrees} and 1200{degrees}C for 10 h, and (2) air at 1000{degrees}, 1200{degrees}, and 1400{degrees}C for times up to 100 h. Individual fibers were tested in tension at room temperature following exposure, and correlations were made between the measured strengths and observed changes in surface morphology including that of the fracture surfaces. Thermal degradation of both fibers occurred under all conditions investigated. In fact, the effect of temperature far outweighed the effect of any other variable including the level of oxidant in the atmosphere, or exposure time. Although of significant different chemistry, degree of crystallinity (Nicalon is crystalline, HPZ is amorphous), and cross-sectional geometry, the strengths of the fibers and their response to the various exposures were remarkably similar with one exception. The strength of the HPZ fiber was significantly less degraded by exposure in air at 1400{degrees}C for times greater than two hours. 19 refs., 6 figs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5854775
• Report Number(s): CONF-910731-1; ON: DE91011099
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
CARBIDES
CARBON
CARBON COMPOUNDS
CERAMICS
CHEMICAL REACTIONS
CORROSION
ELEMENTS
ENVIRONMENTAL EXPOSURE
FIBERS
GEOMETRY
MATHEMATICS
MECHANICAL PROPERTIES
NITROGEN
NONMETALS
SEMIMETALS
SILICON
SILICON CARBIDES
SILICON COMPOUNDS
TEMPERATURE EFFECTS
TENSILE PROPERTIES
THERMAL DEGRADATION