Ceramics-Silikáty

The spontaneous combustion of coal (CSC) presents severe safety and environmental challenges, demanding advanced, thermally stable inhibitors. This study reports the design and fabrication of a porous ceramic–polymer composite foam gel (CPCFG) integrating an amorphous silica scaffold with a polyacrylamide hydrogel network via sol-gel foaming and in-situ polymerisation. The CPCFG exhibits a hierarchical structure with tuneable porosity (76–93%) and a BET surface area decreasing from 352.4 m²/g for the pure ceramic foam to 48.5 m²/g for the CPCFG-H sample, confirming complete pore infiltration. The thermal analysis demonstrated that CPCFG-H delayed the coal ignition temperature from 350 °C to 480 °C and increased the final char residue to 48.8%. The cone calorimetry revealed a five-fold increase in time to ignition (25 vs. 158 s for the raw coal), a 70% reduction in the peak heat release rate (76.3 kW/m²), and a significant decrease in smoke production. The temperature-programmed oxidation experiments showed that the onset of oxygen consumption was delayed from 70 °C to above 180 °C, and CO emission at 170 °C dropped from 180 mmol/cm³·s to 25 mmol/cm³.s, corresponding to an 85% inhibition efficiency. These results confirm a synergistic suppression mechanism combining physical oxygen isolation, endothermic water evaporation, thermal insulation by the silica scaffold, and self-sealing crack behaviour. This facile and scalable CPCFG design offers a robust, long-lasting barrier against CSC, representing a promising next-generation material for mine fire prevention and storage safety applications.