Influence of Contents of Pre-Synthesized Spinel on the Microstructures and Mechanical Properties of the Lightweight Corundum-Spinel Refractory Castables

Abstract

Five kinds of lightweight refractory castables were prepared by using lightweight corundum-spinel aggregates (LCSA), pre-synthesized spinel (PSS), magnesia and corundum powders as raw materials. Effects of the PSS contents on the microstructures and mechanical properties of the refractory castables were studied by means of X-ray diffractometer (XRD), elastic modulus tester and scanning electron microscopy (SEM), etc. It is found that with the PPS content increase from 0 to 15.3 wt %, the permanent linear change (PLC) of castables sintered at 1600 °C decreases from 1.02% to -0.56%; the bulk density (BD) and apparent porosity (AP) are in the range of 29.6 %~27.8 % and 2.71~2.79 g/cm3, respectively, changing a little; the cold compressive strength (CCS) decreases from 106.0 MPa to 94.4 MPa; the thermal shock resistance improves; the hot modulus of rupture (HMOR) decreases from 6.7 MPa to 4.3 MPa. Considering these aspects, sample with 7.6 wt% PPS (LA7.6) has the best performance.