Kinetics and mechanisms of high-temperature creep in silicon carbide: II, chemically vapor deposited

Journal Article · Thu Nov 01 04:00:00 EST 1984 · J. Am. Ceram. Soc.; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1984.tb19510.x· OSTI ID:5090160

Carter, C H; Bentley, J; Davis, R F

Chemically vapor deposited (CVD) silicon carbide was subjected to constant compressive stresses (110 to 220 MN/m/sup 2/) at high temperatures (1848 to 2023 K) in order to determine the controlling steady-state creep mechanisms under these conditions. An extensive TEM study was also conducted to facilitate this determination. The strong preferred crystallographic orientation of this material causes the creep rate to be very dependent on specimen orientation. The stress exponent, n, in the equation epsilon ..cap alpha..sigma'' was calculated to be 2.3 below 1923 K and 3.7 at 1923 K. The activation energy for steady-state creep was determined to be 175 +/- 5 kJ/mol throughout the temperature range employed. At temperatures between 1673 and 1873 K, the controlling creep mechanism for CVD SiC is dislocation glide, which is believed to be controlled by the Peierls stress. Although the activation energy does not change, the increase in the stress exponent for samples deformed at 1923 K suggests that the controlling creep mechanism becomes dislocation glide/climb controlled by climb.

• Research Organization: North Carolina State University, Department of Materials Engineering, Raleigh, North Carolina
• OSTI ID: 5090160
• Journal Information: J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 67:11; ISSN JACTA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360102* -- Metals & Alloys-- Structure & Phase Studies
ACTIVATION ENERGY
CARBIDES
CARBON COMPOUNDS
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
COMPRESSION
CREEP
CRYSTAL STRUCTURE
CRYSTALLOGRAPHY
DEPOSITION
ELECTRON MICROSCOPY
ENERGY
GRAIN ORIENTATION
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
ORIENTATION
SILICON CARBIDES
SILICON COMPOUNDS
STRESS ANALYSIS
STRESSES
SURFACE COATING
TEMPERATURE EFFECTS
THERMAL STRESSES
TRANSMISSION ELECTRON MICROSCOPY
VERY HIGH TEMPERATURE