Research on Design of Sol-Gel Reaction for Creating Ceramic Composites

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The world-wide research has been conducted on the ceramic composite which should be important new materials in coming 21st century. The aim of the present research was to inquire the Potentiality of the sol-gel method in fabricating those composite. The sol-gel method can provide us with new combinations of materials which are not accessible in the conventional techniques, since this makes possible to produce ceramics at relatively low processing temperatures. Following is the summary of research results.1. The organic/inorganic hybrid materials with elasticity was made from CH_3Si(OC_2H_5)_3 through the sol-gel reaction.2. The hybrid led to the SiO_2 glass containing a large amount of isolated carbon particles which could not be obtained by conventional method. On heating the hybrid, 4-fold SiO_4 ring structure was converted to more open ring structure to give SiO_2 glass.3. The dispersion of colloidal SiO_2 particles in the SiO_2 gel fibers suppressed the formation of microcracks in the fibers during heating, resulting in the strengthening of the sol-gel derived SiO_2 glass fibers by a factor of 1.5.4. SiC whisker/mullite composite with high density was produced, where monolithic gel of 2Al_2O_3.SiO_2 composition containing SiC whisker and a small amount of crystalline mullite fine particles was successfully converted to the composite only by heating in air.5. TiN coating (anti-abrasion), SiO_2-TiO_2 coating (anti-oxidation) were applied to graphite materials.6. Several kinds of ceramic fibers such as ZrO_2, PbTiO_3 and BaTiO_3 were prepared by the sol-gel process.Above results indicate the potentiality of sol-gel method in creating new ceramic composites, although 1-6 have still some problems to be overcome.