Preparation of ceramic foams from ceramic tile polishing waste and fly ash without added foaming agent

Ceramic foams were prepared from ceramic tile polishing waste and fly ash with borax as a fluxing agent at 925 °C. The foaming mechanism of SiC and the effects of borax on the mechanical properties, cellular morphology, and phase composition were investigated. The addition of 18 wt% borax lowered the sintering temperature by 300 °C and accelerated the passive oxidation of SiC, thus promoting the foaming process. The optimum ceramic foam obtained at 925 °C featured a homogenous porous structure, with an average pore diameter, low bulk density, high compressive strength, and high porosity of 1.20 mm, 0.55 g/cm3, 7.8 MPa, and 79.4%, respectively. The excellent mechanical properties make ceramic foams potential candidates for lightweight panels for partition walls and ceiling tiles in building applications.