Rolling-contact fatigue and wear of CVD-SiC with residual surface compression
- Univ. of Utah, Salt Lake City, UT (United States). Dept. of Materials Science and Engineering
- Ceramatec, Inc., Salt Lake City, UT (United States)
The rolling-contact fatigue life and wear of CVD-SiC coatings with surface compression were studied using a three-ball-on-rod rolling-contact fatigue (RCF) tester. Two levels of surface compression in the coatings, approximately 190 {micro}m thick, were introduced by using substrates of a liquid-phase sintered SiC and a SiC-30 vol% TiC to obtain desired thermal-expansion mismatches with the CVD-SiC. Residual surface compressions of 250 and 680 MPa were measured in the CVD-SiC coatings on SiC and SiC-30 vol% TiC substrates, respectively, by a strain-gage technique. In the RCF test, the fatigue life of the CVD-SiC coating with the moderate surface compression was limited by severe wear by a brittle fracture mechanism at a Hertzian contact stress of 5.5 GPa. The CVD-SiC coating on the SiC-30 vol% TiC composite, on the other hand, did not show measurable wear. A majority of the tests (11 out of 16) were suspended at 100 h or stopped due to failure of the steel balls. Five tests stopped due to spalling of the CVD-SiC coating at weak interfaces 10 to 15 {micro}m below the contact surface. Examination of the microstructure of the CVD-SiC coating in cross sections revealed that the weak interfaces that led to the spalling were related to discontinuous growth of the CVD-SiC in the form of nodules or growth regions. Elimination of these defective structures is likely to enhance the tribological performance of surface-toughened CVD-SiC.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 116083
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 9 Vol. 78; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
Similar Records
Rolling contact fatigue characteristics of thermal sprayed tungsten carbide coatings
Rolling contact fatigue testing of thermally sprayed coatings