Formation of porous SiC ceramics by pyrolysis of wood impregnated with silica

Biomorphous beta-SiC ceramics were produced at 1400 degrees 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 m(2)/g surface area and has a hybrid pore structure with large 5-20 mu m tubular macropores and small (< 50 nm) slit-shaped mesopores. SiC whiskers of 20-400 nm in diameter and 5-20 mu m 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 similar to 30 nm. The SiC nanopowder produced in this process may be used for manufacturing SiC ceramics for structural, tribological, and other applications.