Fabrication of foamed ceramics with enhanced compressive strength and low thermal conductivity via a simple route

To recycle application of polishing porcelain stoneware tile residues (PPR), foamed ceramics were usually considered as an effective way. In this study, a kind of foamed ceramic was synthesized, simulating the main phase of PPR. The effects of SiO 2 addition on crystalline phase, microstructure, physical properties, thermal conductivity , mechanical performance were systematically investigated, the related mechanism was discussed in detail as well. With the increase of SiO 2 , a large amount of spinel was formed in the foamed ceramics. The results demonstrated that the foamed ceramic with 10 wt% SiO 2 powder, sintered at 1200 °C for 30 min, possesses compressive strength of ~30.6 MPa, thermal conductivity of ~0.43 W*m −1 k −1 , average pore size of ~15 μm and porosity of ~44.1%. A unique structure with gaps in the pore wall of sample containing 10 wt % SiO 2 was found, which gives the foamed ceramics high compressive strength and low thermal conductivity.