Effect of synthesis conditions on cristobalite crystallization in low-cost ceramic membranes

The raw materials quartz, calcite, kaolin, and zeolite were used to fabricate /f-cristobalite-based ceramic membranes at low temperatures. The raw materials were divided into two groups: calcite and zeolite. Calcite and zeolite raw material mixtures were prepared in different proportions by weight. Quartz-calcite-kaolin and quartz-zeolite-kaolin raw material mixtures were subjected to grinding, drying and shaping processes and then sintered separately at temperatures of 1100 degrees C, 1150 degrees C, and 1200 degrees C in a 7-hour furnace regime. All samples were subjected to X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), density, and mechanical testing. The effects of various raw materials with different compositions and sintering temperatures on the characteristics of ceramic membranes were examined. The necessary conditions for sufficient cristobalite production were created by a sintering temperature of 1200 degrees C with zeolite as the raw material. These criteria are also suitable for homogeneous pore size distribution and crystal structure formation. The flexural strength of the membrane containing 10 wt.% zeolite sintered at 1200 degrees C was 34.75 N.mm-2. The average pore diameter of the membrane sintered at 1200 degrees C with an initial zeolite content of 25 wt.%, was 33.95 nm.