The microstructure and refractory properties of the prepared castable samples were investigated by using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, permanent linear changes (PLC) test and refractoriness under load (RUL) test. The slag-attack resistance test was applied to determine the degree of penetration of slag and/or the rate of corrosion. The results of these investigations were related as much as possible to each other.
The investigated castable samples showed characteristic positive PLC and good volume stability (linear change <1 % ). They started softening at about 1300 °C followed by the rapid subsidence. They showed a somewhat decrease in penetration by the molten slag and a slight increase in corrosion as the spinel (preformed or in situ) content increases. The castable samples containing in situ spinel showed an increase in resistance to slag-penetration and a slightly higher corrosion due to slag attack compared to castable samples containing preformed spinel.