The role of interfacial coatings on the high frequency fatigue behavior of Nicalon/C/SiC composites
- Univ. of Michigan, Ann Arbor, MI (United States)
- Oak Ridge National Lab., TN (United States)
A significant number of researchers have shown that, under monotonic loading, a weak fiber/matrix interface is desirable in obtaining toughness and graceful failure in continuous fiber reinforced ceramic composites (CFCCs). Such an interface is usually accomplished by the insertion of a thin coating (typically 0.1--1 {micro}m thick) such as C or BN, which is compliant enough to relieve residual clamping stresses from processing, and whose structure consists of several weakly bonded basal planes. Holmes et al. showed that in a unidirectional Nicalon/CAS composite with a weak interface, increasing loading frequency caused a significant decrease in fatigue life. Due to repeated frictional sliding of fibers, a significant amount of heat is generated by the specimen, and a large temperature rise is observed. In fact, Sorensen and Holmes have shown that immersing specimens in oil, in order to create a lubricating layer at the fiber/matrix interface, can dramatically improve the fatigue life of the composite. Following this observation of Sorensen and Holmes, the authors have hypothesized that thicker interfacial coatings may improve the fatigue life of CFCCs. To this end, Nicalon/SiC composites were examined, with a carbon coating of 0.33 and 1.1 {micro}m. The samples were identical in nature, except for the interfacial coating thickness.
- Sponsoring Organization:
- Department of the Air Force, Washington, DC (United States)
- OSTI ID:
- 413247
- Journal Information:
- Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 12 Vol. 35; ISSN 1359-6462; ISSN SCMAF7
- Country of Publication:
- United States
- Language:
- English
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