Resistance of alumina-spodumene ceramics to thermal shock

A processing strategy is presented for obtaining alumina-spodumene ceramics with controlled microstructures from a new, low-cost alumina powder and spodumene (Li2O . Al2O3. 4SiO(2)) mineral, both being produced in Western Australia. The addition of 15 wt% beta-spodumene to alumina is used to produce ceramics with (i) high thermal expansion mismatch and (ii) a glassy phase to aid in liquid-phase sintering, Specifically, the effects of spodumene addition and grain size on tolerance to thermal shock are addressed, The thermal shock resistance of the alumina-spodumene ceramics is evaluated by water quenching and subsequent three-point bend testing of strength diminution, Comparisons are made with results from parallel experiments conducted using a pure monolithic alumina ceramic, The reference alumina shows the expected substantial strength losses when thermally quenched from similar to 200 degrees C above room temperature. By contrast, the alumina-spodumene ceramics, while displaying reduced strength relative to the reference aluminas, exhibit minimal strength degradation under severe thermal shock conditions.