Resistance of Alumina‐Spodumene Ceramics to Thermal Shock

Abstract

A processing strategy is presented for obtaining alumina‐spodumene ceramics with controlled microstructures from a new, low‐cost alumina powder and spodumene (Li2OAl2O3·4SiO2) mineral, both being produced in Western Australia. The addition of 15 wt%β‐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 ∼200°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.