Fabrication of nanoporous silicon carbide fibres by thermal treatment

Abstract

Nanoporous silicon carbide fibres were prepared by curing and heat treatment of melt spun polycarbosilane (PCS) fibres. During the curing process, green PCS fibres were thermally oxidised at the temperature between 180 and 220°C and time between 2 and 10 h for cross-linking among the molecule chains in the PCS and controlling the oxygen concentration and distribution. After thermal oxidation, fibres were heat-treated between 1200 and 1600°C for the conversion to SiC phase. About 15–20 wt-% of oxygen was analysed after heat treatment at 1200°C and it can be possible to pyrolyse without melting or deformation of fibre. At a temperature above 1400°C, the uniform distribution of nanopores was observed on the fibre surface, and the size of pores was increased with curing and heating condition. This type of nanoporous SiC fibre is expected to be a good candidate for high temperature catalyst or catalytic supports.

Formation of ZSM-5 on Silicon Carbide Fibers for Catalytic Support

“…SiO 2 was selected to the buffer layer because it was ease to make dense SiO 2 layer on the SiC fiber through simple oxidation and compositionally similar to ZSM-5. Okamura et al and other previous study confirmed that SiO 2 oxidation layer having α-cristobalite of crystal phase was formed during oxidation above 1,000 ºC, which was act as protection layer [21][22][23][24]. The formation mechanism of SiO 2 on the SiC fiber is followed by simple reaction equation depending on the oxidation temperature and time:…”

“…SiC fiber was prepared by melt spinning of polycarbosilane (PCS) and pyrolysis [20][21][22]. PCS fiber was obtained using a melt spinning apparatus with a spinneret having 500 μm single nozzle under the argon gas pressure.…”

Thermophysical properties and processing of ceramics

“…Nanoporous SiC fibres can be a potential candidate in catalysts and catalytic supports for high-temperature applications. Shin et al 4 report that nanoporous SiC fibres, in which the nanopores were uniformly distributed on the fibre surface, were investigated by controlling the thermal oxidation and heat-treatment conditions; their microstructural evolution with formation behavior are also discussed. Kim et al 5 present that cellulose-calcium silicate (CCS) nanocomposites were fabricated through an environmentally friendly process from waste wood, glass, and clamshells.…”