Spalling resistance of refractory bricks containing 60－99％ zircon was investigated by measuring 3－
point bending strength of specimens quenched into water from various temperatures．Bending strength
and Young’s modulus of zircon bricks quenched decreased continuously with increasing quenching
temperature difference，because the fairly large cracks in the bricks propagated stably under various
conditions of thermal shock．
Spalling resistance of zircon bricks，as measured by the relative retained in a water quench，correlated well with the thermal stress resistance（crack stability）parameter Rst and the thermal shock damage resistance parameter R’’’’．
