Sintering of MgO-based refractories with added WO3

The effects of WO3 on properties of MgO-based refractories were studied and microstructures analyzed using scanning electron microscopy (SEM) and EDS. WO3 can improve the sintering of MgO-based refractories. <2 wt% WO3 is favorable to improve the cold modulus of rupture of MgO-based refractories, but high levels of WO3 have a negative effect on cold MOR and thermal shock. The low melting phases MgWO4 and CaWO4 formed in MgO boundaries result in increased liquid volume. The formation of CaWO4 leads to C/S ratio change and decreased levels of C3S and C2S, and the low melting phase CMS forms. Thus, the densification is improved by phase liquid sintering. SEM observation confirms the existence of CaWO4 and MgWO4 grain boundary phases.