In situ measurement of fatigue crack growth rates in a silicon carbide ceramic at elevated temperatures using a DC potential system

Citation
D. Chen et al., In situ measurement of fatigue crack growth rates in a silicon carbide ceramic at elevated temperatures using a DC potential system, J TEST EVAL, 28(4), 2000, pp. 236-241
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science & Engineering
Journal title
JOURNAL OF TESTING AND EVALUATION
ISSN journal
0090-3973 → ACNP
Volume
28
Issue
4
Year of publication
2000
Pages
236 - 241
Database
ISI
SICI code
0090-3973(200007)28:4<236:ISMOFC>2.0.ZU;2-5
Abstract
The understanding of the mechanisms of fatigue-crack propagation in advance d ceramics at elevated temperatures (>800 degrees C) has in part been hampe red by the experimental difficulty in directly measuring crack lengths, and hence crack growth rates, at such high temperatures. In this study, we sho w how the direct-current (DC) electrical-potential technique, which has bee n used for such measurements in metallic materials for over 30 years, can b e successfully utilized to monitor fatigue crack growth rates in situ in a silicon carbide ceramic at temperatures between 850 and 1300 degrees C, bec ause of the electrical conductivity in SiC at these temperatures. In additi on to providing a highly efficient means of collecting such data, this appr oach offers several significant advantages over the techniques that have be en used to date for advanced ceramics, particularly in avoiding artifacts d ue to thermal fatigue and oxidation from repeated exposure to air and/or lo wer temperatures while making measurements. Effects of parameters such as l oad ratio and loading frequency are examined, both on crack growth behavior and the accuracy of measurement. With appropriate considerations, electric al-potential calibrations determined at ambient temperatures in metallic ma terials can be applied readily to elevated temperature measurements in sili con carbide.