Crack-free caustic magnesia-bonded refractory castables

A growing interest in designing high-alumina MgO-bonded refractory castables has been identified recent years due to the magnesia ability react: (i) with water at initial processing stages of these materials (inducing precipitation brucite phase) or (ii) alumina, giving rise situ MgAl2O4 generation high temperatures. Nevertheless, despite great potential caustic be used as a binder such systems its reactivity, it is still challenge control hydration reaction rate this oxide and negative effects derived from expansive feature Mg(OH)2 formation. Thus, work evaluated incorporation different contents aluminum hydroxyl lactate (AHL) into magnesia-bonded castables, aiming during curing drying steps prepared samples, resulting crack-free refractories. The designed compositions were characterized via flowability, setting behavior, X-ray diffraction, cold flexural strength, porosity, permeability thermogravimetric measurements. According results, instead Mg(OH)2, hydrotalcite-like phases [Mg6Al2(OH)16(OH)2.4.5H2O Mg6Al2(OH)16(CO3).4H2O] main hydrated AHL-containing compositions. addition 1.0 wt.% castable proved be, so far, best option for source, development enhanced properties greater spalling resistance under heating.