Microstructure and role of outermost coating for tensile strength of SiC fiber
- Univ. of Tokyo (Japan). Inst. of Industrial Science
- National Research Inst. for Metals, Tsukuba, Ibaraki (Japan)
The detailed microstructure of the SiC fiber surface and the outermost coating of SiC(SCS-6) fiber are observed using transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). The tensile strengths of the SiC fibers: uncoated fiber (SCS-0), coated fiber (SCS-6) and extracted fiber from fatigue-loaded SiC(SCS-6) fiber-reinforced Ti-15-3 composite are determined. Fractographic analysis is done on these fibers and the mirror radius is compared with the tensile strength. Thickness of the outermost coating is {approx}3.6 {micro}m and it consists of three different layers (i.e., sublayers 1, 2 and 3). Basically, these sublayers consist of a carbon matrix in which {beta}-SiC crystallites are dispersed. The fracture toughness of the SiC fiber is {approx}3.3 MPa m{sup 1/2}. The outermost coating increases the fiber strength twofold because it reduces stress concentration at the surface of the SiC fiber. The tensile strength of the extracted fiber (SCS-6) from fatigue-loaded specimens shows a reduced strength which is attributed to the debonding of the outermost coating while the composite is loaded.
- OSTI ID:
- 669793
- Journal Information:
- Acta Materialia, Vol. 46, Issue 14; Other Information: PBD: 1 Sep 1998
- Country of Publication:
- United States
- Language:
- English
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