For fused cast AZS bricks, expansion is common. And it will have effect on the properties of the bricks.
The expansion is up to the composition of the raw materials and the firing temperature as well as porosity. When used in wet conditions, the repeated heating and cooling will exacerbate the expansion. The expansion of fused cast AZS is intensified with the rising of water temperature and the extension of the action time.
The diameter of water molecule is about 0.2um, while the diameter of the particles of AZS refractory is about 1000 times greater than that of water molecule, even greater. Due to thermal motion, water molecule is easy to penetrate into the AZS refractory and causes micro cracks. When steam or water molecule diffuses along micro cracks and reaches a narrow place, the pressure increases to 100Mpa. This causes the extension of cracks.
Water vapor is adhered to the capillary walls of fused cast AZS bricks. The AZS materials form hydrates or eutectic melt. Glass phase is hydrated. Clay and its decomposed products adsorb moisture. All these may cause expansion.
