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 SiO2 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 SiO2, a large amount of spinel was formed in the foamed ceramics. The results demonstrated that the foamed ceramic with 10 wt% SiO2 powder, sintered at 1200 degrees C for 30 min, possesses compressive strength of similar to 30.6 MPa, thermal conductivity of similar to 0.43 W*m(-1)k(-1), average pore size of similar to 15 mu m and porosity of similar to 44.1%. A unique structure with gaps in the pore wall of sample containing 10 wt % SiO2 was found, which gives the foamed ceramics high compressive strength and low thermal conductivity.