High pressured processing of nano particle and whisker reinforced ceramic composites

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(1) Alumina matrix composites which were reinforced by SiC and Y_2O_3 particles were produced by the hot press equipment. Mechanical parameters such as denstiy, grain size and so on were changed by controlling process temperature. We succeeded in producing Al_2O_3/SiC nano composite and Al_2O_3/SiC/YAG hybrid composite. (2) The generation of YAG as secondary phase found by X-ray deflection analysis. (3) Materials were densified by increasing of sintering temperature. Monolithic materials were fully desified over 1400ﾟC. Composites were fully desified between 1400ﾟC and 1600ﾟC. (4) Addition of SiC particles the grow of grain. Also the generation of YAG phase decreased the grain size of matrix. (5) Nano composites structure with dispensed SiC particles was clearly observed by transmission electron microscope. (6) Four point strength was increased by addition of SiC and Y_2O_3 because it decreased a grain size and increased relative density. Fracture toughness was improved in Al_2O_3/SiC/YAG composite by the increase of deflection in crack propagation. It was demonstrated that nano or hybrid composites could improve the mechanical properties of ceramics.