Microstructure comparison of transparent and opaque CVD SiC
- Univ. of Illinois, Urbana, IL (United States)
- Morton Advanced Materials, Woburn, MA (United States)
Transparent, translucent, and opaque regions of high-purity bulk SiC, produced by CVD, have been characterized for physical properties as well as microstructure and chemical purity to correlate degree of transparency with other material characteristics. A good correlation was obtained between SiC vis-a-vis IR transmission and its microstructure. The transparent material is highly oriented toward the {l_angle}111{r_angle} direction and is characterized by pure, essentially defect-free, cubic {beta}-SiC columnar grains of size 5--10 {micro}m. The translucent material of various colors is mostly cubic in structure but contains large amounts of twins, usually as complex mixtures of several twinning variants and secondary twinning within a single grain. Opaque CVD SiC is randomly oriented, does not exhibit columnar grains, and contains one directional disorder with hexagonal ({alpha}-SiC) symmetry in a majority of grains and high density of dislocations elsewhere.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG02-91ER45439
- OSTI ID:
- 82626
- Journal Information:
- Journal of the American Ceramic Society, Vol. 78, Issue 6; Other Information: PBD: Jun 1995
- Country of Publication:
- United States
- Language:
- English
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