index SLM-0.6 SLM-0.7 SLM-0.8 SLM-0.9 SLM-1.0 SLM-0.2 AL2O3% No less than 48 48 48 50 52 54 Fe2O3% no more than 1 1 1 1 1 1 g/cm3 Bulk density 0.6 0.7 0.8 0.9 1.0 1.2 MPa cold compressive strength no less than 2.2 2.3 3.2 3.7 4.0 4.5 Experiment temperature of change of re-fired curve no more than2% 1350 1350 1350 1400 1400 1450 Thermal conductivity average temperature 0.20 0.22 0.27 0.29 0.32 0.35