Macroporous monoliths based оn natural mineral sources, clay аnd diatomite

Abstract

Macroporous silica ceramic was obtained using clay and diatomite. Boric acid as a low-cost additive in the amount of 1 wt% was used. These porous materials were obtained at low forming pressure (40-80 MPa) and lower sintering temperature (850-1300 ºC) for 4h in air. The influence of boric acid, forming pressure, and sintering temperature on the microstructure, porosity parameters, and mechanical properties of obtained porous monoliths were investigated. As-received and the modified samples were characterized by X-ray diffraction, FTIR, SEM, and mercury porosimetry measurements. As for modified clay and diatomite, they were pressed at 60 MPa and then sintered at 1150 ºC, obtaining porosities of about 10 % and 60 %, respectively. Both of the analyzed samples had the pore diameter in the range of macroporous materials. The pore diameters of clay samples are ranging from 0.1-10 μm, whereas the pore diameter of diatomite samples was slightly lower with values ranging from 0.05-5 μm. Modified diatomite samples have a lower Young modulus in comparison to modified clay samples.

Keywords

• sintering
• macroporosity
• clays
• diatomite
• boric acid