Preparation and Characterization of Heat-Resistant Ceramics from Hydrolyzed Aluminum Salt Slag Waste

The valorization of industrial by-products into heat-resistant ceramics offers a promising route for resource recovery and waste management. In this study, hydrolyzed aluminum salt slag (71.42–82.71 wt.%) was utilized alongside silica sand to synthesize ceramic bodies. The compacted green bodies were fired at 1450 °C for 2 h and evaluated for physical, mechanical, structural, and dielectric properties. X-ray diffraction analysis revealed mullite, MgAl2O4 spinel, corundum, and quartz as the primary crystalline phases. Sintering yielded bulk density values ranging from 1.80 to 2.30 g cm−3, apparent porosity between 13.28% and 25.05%, and bending strength between 13.93 and 18.53 MPa. Broadband dielectric spectroscopy (10−1–106 Hz) confirmed electrically insulating behavior dominated by Maxwell–Wagner–Sillars interfacial polarization, with Havriliak–Negami relaxation modeling tracking phase heterogeneity. These findings confirm the technical feasibility of incorporating high proportions of hydrolyzed salt slag into heat-resistant and electrically insulating ceramics.