Microstructure and Properties of a Fine Grained Eutectic Ceramic Composite

摘要

Al_2O_3-ZrO_2 melt growth eutectic ceramic oxides (MGC) are generally expected to be the most interesting and attractive as the new generation high temperature structural material applied at elevated temperature in the oxidizing environment. However, lack of effective shaping technology is a critical technical issue for its practical application for a long time. In this paper the Al_2O_3-ZrO_2 binary eutectic ceramic was prepared. At first, nano-sized Al_2O_3-ZrO_2 powders were sintered by the spark plasma sintering at 1500℃. Then as-sintered sample was melted at 1850℃ in vacuum to get the MGC. The results demonstrate that the microstructure of the MGC is the three-dimensional interpenetrating network structure. The characteristic of the microstructure is the simultaneous growing lamellar structure of two phases from the melt. The hardness and fracture toughness of MGC were 1120MPa and 13MPa·m~(1/2) respectively, which were significantly higher than that of the as-sintered composite. The superplastic forming of the as-sintered composite ceramic was also investigated.