Formation of Porous SiC Ceramics by Pyrolysis of Wood Impregnated with Silica

Abstract

Biomorphous β‐SiC ceramics were produced at 1400°C from pine wood impregnated with silica. This one‐step carbothermal reduction process decreases the cost of manufacturing of SiC ceramics compared with siliconization of carbonized wood in silicon vapor. The synthesized sample exhibits a 14 m2/g surface area and has a hybrid pore structure with large 5–20 μm tubular macropores and small (<50 nm) slit‐shaped mesopores. SiC whiskers of 20–400 nm in diameter and 5–20 μm in length formed within the tubular pores. These whiskers are expected to improve the filtration by removing dust particles that could otherwise penetrate through large pores. After ultrasonic milling, the powdered sample showed an average particle size of ∼30 nm. The SiC nanopowder produced in this process may be used for manufacturing SiC ceramics for structural, tribological, and other applications.

Preparation of biomorphic SiC

“…Another process for the preparation of biomorphic SiC [6][7][8] is the impregnation of a carbon template with SiO 2 sol, which allows one to produce a SiO 2 layer of desired thickness on the surface of the template. The template is then subjected to high temperature heat treatment, which leads to the formation of SiC through the carbothermic reaction (2) Carbon templates can be silicided as well by other processes, with the use of more "exotic" silicon precur sors.…”

Síntesis de whiskers de SiC asistida por microondas

“…La síntesis del SiC se lleva a cabo en estado sólido y es heterogénea, en el caso específico de los whiskers se emplean dos técnicas para su síntesis: la pirolisisy la deposición de vapor [17,18].…”

Optimized vacuum/pressure sol impregnation processing of wood for the synthesis of porous, biomorphic SiC ceramics

“…organic precursors, 7 and reactive infiltration with Si-containing melts. [8][9][10][11][12][13] Impregnation with SiO 2 nanoparticles containing sol, [14][15][16][17] with Na 2 O·nSiO 2 , 18 with Si-containing polymer, 19 with metal organic precursors [20][21][22][23][24] and with sol-gel derived SiO 2 sol 25 was performed via the following carbothermal reactions. Comparing the previously mentioned methods, the sol-gel impregnation method with the following carbothermal reaction has some advantages such as low cost, easy procedure and the ability to retain the structure and morphology of the starting carbonaceous precursor material.…”