Elevated temperature mechanical properties of compositionally varied Si/SiC composites
- Univ. of Cincinnati, OH (United States)
The elevated-temperature mechanical properties of Si/SiC composites were studied as a function of Si content. Si/SiC composites containing 10 to 50 vol% Si were fabricated using molten Si to infiltrate porous preforms consisting of varying ratios of carbon to SiC powders and then react with carbon forming SiC. Four-point flexural tests were then used to measure the strength, elastic modulus and creep rates at room and elevated temperatures from 1250 to 1550{degrees}C. Elastic modulus and strength were shown to decrease with increases in both Si content and temperature. The composites containing large amounts of continuous Si exhibited extremely low strength near the melting point of Si, while the composites containing small amounts of Si with a continuous SiC network retained 120 to 200 MPa even above the melting point of Si. Creep tests showed a correlation of decreasing creep resistance with increasing Si content. The composites containing 10 and 20 vol% Si showed similar stress exponents (4.3 and 3.0, respectively) and activation energies (878 and 907 kJ/mol, respectively) above the melting point of Si and in a stress range of 60 to 140 MPa. These values suggested a dislocation glide/climb mechanism. Stress exponent of 10.3 and 6.5 and activation energy of 768 and 600 kJ/mol were found for the composites containing 36 and 45 vol% Si in a temperature range of 1250 to 1350{degrees}C and stress range of 300 to 400 MPa, respectively.
- DOE Contract Number:
- FG02-91ER45459
- OSTI ID:
- 530700
- Report Number(s):
- CONF-9604124-; TRN: 97:003389-0036
- Resource Relation:
- Conference: 98. annual meeting of the American Ceramic Society, Indianapolis, IN (United States), 14-17 Apr 1996; Other Information: PBD: 1996; Related Information: Is Part Of Ceramic transactions: Advances in ceramic-matrix composites III. Volume 74; Bansal, N.P.; Singh, J.P. [eds.]; PB: 667 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Fracture and creep of an Al{sub 2}O{sub 3}-SiC(whisker)-TiC(particle) composite.
Deformation and microstructural changes in SiC whisker-reinforced Si sub 3 N sub 4 composites