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Preparation of Porous SiC by Freeze Drying of Polycarbosilane Emulsion

폴리카보실란 에멀젼의 동결건조를 이용한 다공체 SiC 제조

  • Received : 2016.01.06
  • Accepted : 2016.04.27
  • Published : 2016.06.27

Abstract

Porous SiC beads were prepared by freeze-drying a polycarbosilane (PCS) emulsion. The water-in-oil (w/o) emulsion, which was composed of water, PCS dissolved p-xylene, and sodium xylenesulfonate (SXS) as an emulsifier, was frozen by dropping it onto a liquid $N_2$ bath; this process resulted in 1~2 mm sized beads. Beads were cured at $200^{\circ}C$ for 1 h in air and heat-treated at $800^{\circ}C$ and $1400^{\circ}C$ for 1 h in an Ar gas flow. Two types of pores, lamella-shaped and spherical pores, were observed. Lamellar-shaped pores were found to develop during the freezing of the xylene solvent. Water droplets in the w/o emulsion were changed into spherical pores under freeze-drying. At $1400^{\circ}C$ of heat-treatment, porous SiC was synthesized with a low level of impurities.

Keywords

polycarbosilane;porous SiC;freeze-drying;polymer emulsion

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Acknowledgement

Supported by : Seoul National University of Science and Technology