A study of the sintering of diatomaceous earth to produce porous ceramic monoliths with bimodal porosity and high strength

Diatomite powder, a naturally occurring porous raw material, was used to fabricate ceramic materials with bimodal porosity and high strength. The effect of the sintering temperature on the density and porosity of dry pressed diatomite green bodies was evaluated using mercury porosimetry and water immersion measurements. It was found that the intrinsic porosity of the diatomite particles with a pore size around 0.2 µm was lost at sintering temperatures above 1200 °C. Maintaining the sintering temperature at around 1000 °C resulted in highly porous materials that also displayed a high compressive strength. Microstructural studies by scanning electron microscopy and energy-dispersive X-ray analysis suggested that the pore collapse was facilitated by the presence of low melting impurities like Na2O and K2O.

Diatomaceous earth is used to fabricate porous ceramics with a bimodal porosity by dry pressing and conventional sintering. The effect of the sintering temperature on the microstructure, porosity and strength of porous monoliths is studied in order to better understand the consolidation and melting behavior of the diatomite. Monoliths sintered at 1400 °C show compression strength of as high as 106 MPa.Figure optionsDownload as PowerPoint slide