Rebonded fused cast AZS block is made of AZS frit or waste fused cast AZS block by adding a small amount of kaolin or alumina as binder. Rebonded fused cast AZS block is composed of A12O3 (50-60%), ZrO2 (20-30%) and SiO2 (14-20%).
When heated to a certain temperature, glass phase exuded by fused cast AZS forms mullite with binding agents. Bricks should be fired at 1600-1700℃. The frits should have homogeneous chemical composition and a low content of glass phase. Waste bricks have non-homogeneous composition and a high content of glass phase (15%-25%).
When Fused cast AZS is heated, glass phase is melted and exuded. The exuded glass phase has peritectic reaction with the main crystal phase and forms mullite. In this case, mullite and ZrO2 coexists with each other by wrapping and being wrapped. It makes the fused cast AZS scraps fired into a solid brick. The finer the fused cast AZS scraps are, the bigger the specific surface of glass phase is.
After sintered, rebonded fused cast AZS block has a significant change in microstructure.
1) Glass phase in the fine fused cast AZS reacts with Al2O3 and forms mullite.
2) Glass phase in the coarse granular materials is exuded to the surface and forms a mullite layer by reacting with Al2O3. The layer encloses the liquid exuding channel and ensures the peritectic reaction happens within the particles.
3) After glass phase in the coarse granular materials is all exuded, voids and cracks are left.
Compared to fused cast AZS block, rebonded fused cast AZS block has a higher exudation temperature of glass phase. It has good thermal shock resistance, high temperature mechanical properties, creep resistance and corrosion resistance to glass.