Fabrication And Characterization Of Powder SiOC Micro-/Mesoporous Ceramics From Silicon Resin

Due to unique combination of pore structure and excellent performance of ceramic, SiOC porous ceramics show great potential for a number of industrial applications such as separation, gas storage, catalysis and removal of pollutants and so on. In this dissertation, novel methods of fabricating SiOC porous ceramics from silicon resin were studied, and the results are as followed.Powder SiOC porous ceramics were synthesized from commercial silicon resin (SR249). Components and pore structures of the pyrolysates were systematically studied by some testing methods such as N₂ adsorption, X-ray diffraction, IR, element analysis, SEM and so on.Fabrication Study of powder SiOC porous ceramics was conducted according to pyrolysis behavior of silicon resin in the begingning. The result shows powder SiOC porous ceramics majored in mesorporosity are obtained by pyrolysis between 1250℃and 1450℃. The pore volume and BET surface area can reach to as high as 0.214cm3/g and 65.696m²/g respectively, with the pore size distribution in the range of 0nm up to 30nm.To improve BET surface area and pore volume of the pyrolysates, post treatments were adopted from the scaffold structure of the SiOC ceramics, and the results are as followed.By HF (hydrofluoric)-acid etching for more than 5 hours, powder micro and mesoporous SiOC ceramics (rich in free carbon) were synthesized using the pyrolysates above. The BET surface area and pore volume can each reach as high as 1148m²/g and 0.608cm3/g respectively, with the pore size distribution in the range of 0nm up to 6nm. This kind of porous ceramics with free carbon may show great potential in sorption, separation areas and so on for their good thermal-stability in Ar atmosphere below 1600℃.By oxidation in air at 650℃for more than 4 hours, powder mesoporous SiOC ceramics (without free carbon) were synthesized using the etched products above. The surface area and pore volume can each reach as high as 204.017m²/g and 0.58cm3/g respectively, with the pore size distribution in the range of 4nm up to 12nm. This kind of porous ceramics without free carbon may show great utility value as catalyst supports area in harsh condition.