Development of ceramic microcoils with 3D-herical/spiral structures(The 62th CerSJ Awards for Academic Achievement in Ceramic Science and Technology: Review)

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Various modified CVD processes, such as modified hot filament method, vapor phase diffusion process, in-situ CVD process, catalytic CVD process, for the preparation of ceramics single crystals and fibers were developed. The preparation conditions, morphologies, microstructure and properties of transition metal carbides, nitrides, borides, silicides, sulfides, etc were examined. We have first found that various ceramic fibers with 3D-helical/spiral structure, such as Si_3N_4, carbon, TiC, TiO_2, etc. were obtained using metal-catalyzed CVD and/or vapor phase diffusion processes under critically controlled reaction conditions. Carbon microcoils (CMC) with double-helical structure were obtained with high reproducibility by metal catalyzed pyrolysis of acetylene. The CMCs have many interesting and eminent characteristics, such as 3D-helical/spiral microstructure with μm orders in coil diameters, diverse microstructures from amorphous to graphite structure, changing in electrical parameters under the application of various stimuli, high microwave absorption and microwave heating abilities, breeding or anti-breeding effect on cells, fibrils of organisms, etc.
2008-09-01