| Research Abstract |
Proposed research project has aimed at control of morphology and properties of SiC based ceramic materials derived from heterogeneous precursors in which Si, C, O elements are located with continuous undulation in concentration. First, carbon sources (phenolic resins and carbon blacks) were combined with silicon sources (metal alkoxides and silicone resins with high ceramic yields). Structure of tailored precursors and SiC particle formation process at high temperature heat treatment from precursors were investigated. In the case of phenolic resins, phase separation patterns were formed in the precursors, which depend on the resin viscosity and gelation condition_ Morphology of formed SiC particles reflected such phase separation pattern(J.Appl Potnn Sci, 94, 1612-1618 (2004) ). In the case of carbon black utilization, the rise of the formed SiC also reflected primitive size of the used carbon black. Network structure of the carbon black aggregation observed in the precursors, however,
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was not reflected in the formed SiC particles. In the case of silicone resin utilization, high SiC yield can be achieved as compared with the utilization of Si alkoxide (J. Ceram. .Soc Japan, 116, 121-125 (2008) ). Secondary, viscoelastic properties of SiC slurries of commercialized SiC particles - polycarbosilane -xylem mixtures were investigated in detail, which is expected to have deep relationship with morphology of SiC particles (J. Ceram Soc Japan, 115, 982-986 (2007)). The relationship between shear rate dependence on particle orientation was found in the case of SiC nano particles. It is critically important notice about slurry preparation for matrix impregnation and coating applications. Thirdly, polymer blend systems of polycarbosilane and silicone oil were investigated as melt spinnable precursors. After the melt spinning, phase separation patterns were observed in spun fibers. For achievement of morphology control like continuous hollow fibers, hydrogen gas saturation in the polymer melts would be important factor, which determine the con tenuous pore strictures (lay Eng. Mater, 352, 69-72 (2007)). Less
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