Influence of beta-to-alpha quartz transition on residual stresses of a feldspar glass matrix composite: A relationship with catastrophic fracture due to thermal shock

A wide range of porcelain-based materials is composed of quartz crystalline particles dispersed in a homogeneous glassy phase. During the cooling stage these composites are subjected to stresses related to the transition from beta to alpha quartz at 573 degrees C. This work studies, numerically and experimentally, the influence of the cooling rate, the quantity, and the size of the quartz crystalline particles on the stresses suffered by the material throughout the cooling process. This procedure allows calculating the instantaneous profile of stresses through the cross-section specimen during the whole cooling stage. For this, a dense glass matrix from sodium feldspar was prepared. The results reveal that the evolution of the stress profile is strongly affected by the cooling rate. The evolution of the tension state in the sample during the cooling can help to understand the catastrophic fracture suffered during the beta to alpha quartz transition related to thermal shock.