Processing and characterization of glass-ceramic foams belonging to the Li₂O-ZrO₂-Al₂O₃-SiO₂(LZSA) system produced by gelcasting

In this work the viscosimetry technique was used to evaluate the rheological characteristics of ceramic suspensions prepared with a LZSA (Li₂O-ZrO₂-SiO₂-Al₂O₃) glass. From the rheological characterization it was possible to establish optimized conditions of solid fraction, dispersant, organic monomers and foaming agent for the production of glass-ceramic foams by gelcasting. The resulting foams were subjected to heattreatments at 200-500ºC/60 min, for degradation of organics and at 950ºC/60 min for sintering and crystallization. With the obtained porous ceramic bodies linear thermal shrinkage, apparent density and mechanical strength measurements as well as microstructural analysis were performed. The adaptation of the rheological characteristics of the LZSA parent glass powder with the gelcasting processing technique allowed the production of ceramic foams with high open and interconnected porosity (>90%) with good thermal stability and with mechanical strength suitable for the production of porous ceramics.

rheology; gelcasting; glass-ceramic foams