Doctor of Philosophy (PhD)
As a by-product of the agricultural industry, rice hulls are available at large volume across the world. The disposal of the rice hulls itself is a big problem for the rice millers where the rice paddies are peeled off and rice hulls are produced. There have been many disposal methods developed, but the true value of the rice hulls would be more appreciated when they are employed to produce high value-added advanced ceramics. In this dissertation, advanced ceramics, such as AlN nanowires, SiC whiskers, mullite and SiC/Al2O3 nano-sized composites, were developed and studied based on the rice hulls. The SiC whiskers and AlN fibers were successfully prepared at high yield in a process (patent pending) developed by the author. Since the one-dimensional ceramic materials are valuable raw materials for many industrial applications, the study presented in this dissertation is particularly valuable. During the development of the one-dimensional ceramics, some unique morphology, such as the beaded SiC whiskers were also prepared and investigated. Some potential applications of the prepared ceramics were investigated, such as the application of SiC whiskers as a heat transfer enhancement agent, and the application of beaded SiC whiskers as the reinforcement phase in composites. The heat transfer enhancement by SiC whiskers in a convective flow is promising: an enhancement as high as 27% was achieved by a dispersion of SiC (0.16 wt % in water) at low temperature (300-330 K). The beaded SiC whiskers are confirmed to be an efficient reinforcement phase for plastic-matrix composites, because their special structures would render them a new interlocking mechanism to obtain a much more reliable coupling with the matrix in a composite.
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Zhang, Peigen, "Advanced ceramics and composites based on rice hulls" (2012). LSU Doctoral Dissertations. 3665.