Corrosion of electrocast AZS refractories by CAS glass–ceramics melting

Extensive corrosion experiments on electrocast alumina–zirconia–silica (AZS) refractories by molten CaO–Al2O3–SiO2 (CAS) and Na2O–CaO–SiO2 (NCS) glasses were carried out at various temperatures under static condition. The features and mechanism of the corrosion were compared and analyzed. The changes of microstructure and phase composition of refractories in the course of the melt corrosion were also studied. X-ray diffraction (XRD), scanning electron microscope (SEM) and chemical analysis were used to characterize the corroded refractory materials and reacted melts. The reasons of alumina–zirconia–silica bricks corroded are the meltdown of their own composition, penetration or permeation of alkali oxide in the glass melt and scouring of the glass melt. The results show that the refractories resistance against corrosion of the oxides like Na2O, K2O or CaO is weak, and that the corrosion mechanism of NCS/AZS is different from that of CAS/AZS. In a static condition, CaO–Al2O3–SiO2 melts corroded alumina–zirconia–silica brick more severely than Na2O–CaO–SiO2. The result provides useful reference to a prospective selection of refractory materials in glass and glass–ceramics manufacture.