CVD silicon carbide characterization. Final report, August 1992-October 1993
Chemically vapor deposited (CVD) silicon carbide is a candidate material for high quality ground and space-based mirror substrates and high quality reflective optics. Statistically valid material property data has not been available, however, to make durability and lifetime predictions for such optics. The primary purpose of this study was to determine the Weibull and slow crack growth parameters for CVD silicon carbide. Specimens were cut from various locations in a 25 mm thick, 50 cm diameter piece of SiC to analyze bulk material property homogeneity. Flexural strength was measured using a four-point bend technique. In addition to mechanical testing for strength, hardness, and fracture toughness, the material crystallography and microstructure were studied. Thermal expansion, thermal diffusivity, specific heat, optical absorption, and infrared reflectivity measurements were also conducted. Raman spectroscopy was used to check for any residual stress. Test results show this CVD silicon carbide is a high-purity, homogeneous, fine-grained substrate material with very good mechanical, optical, and thermal properties.
- Research Organization:
- Dayton Univ., OH (United States). Research Inst.
- OSTI ID:
- 7084619
- Report Number(s):
- AD-A-285667/2/XAB; UDR-TR-93-122; CNN: F30602-90-D-0105
- Country of Publication:
- United States
- Language:
- English
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SILICON CARBIDES
CHEMICAL VAPOR DEPOSITION
FLEXURAL STRENGTH
FRACTURE PROPERTIES
THERMAL EXPANSION
CRACK PROPAGATION
CRACKS
FATIGUE
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MICROHARDNESS
MICROSTRUCTURE
PROGRESS REPORT
SPECIFIC HEAT
THERMAL DIFFUSIVITY
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CARBON COMPOUNDS
CHEMICAL COATING
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DOCUMENT TYPES
EXPANSION
MECHANICAL PROPERTIES
PHYSICAL PROPERTIES
SILICON COMPOUNDS
SURFACE COATING
THERMODYNAMIC PROPERTIES
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