Accession Number:

ADA285667

Title:

CVD Silicon Carbide Characterization

Descriptive Note:

Final rept. Aug 1992-Oct 1993

Corporate Author:

DAYTON UNIV OH RESEARCH INST

Personal Author(s):

Report Date:

1994-08-01

Pagination or Media Count:

54.0

Abstract:

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.

Subject Categories:

  • Physical Chemistry
  • Laminates and Composite Materials
  • Manufacturing and Industrial Engineering and Control of Production Systems
  • Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE