The effect of temperature and subcritical crack growth on the R-curve of a 99.5/100 purity coarse grained alumina was studied using chevron-notched, short-bar specimens. Constant loading rate tests were used to measure toughness as a function of crack length and static load tests were used to measure subcritical crack growth as a function of time. It was found that the intrinsic toughness decreased monotonically from 20 to 1200℃ while the bridging contribution to the R-curve remained relatively constant over this temperature range. The constant load tests at 700, 1000 and 1200℃ showed that substantial subcritical crack growth occurs under static loading.
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