DUPLEX SPINEL-ZRO2 CERAMICS

Duplex spinel-ZrO2 ceramic composites were produced by an emulsion-hot kerosene drying technique. The sintered duplex spinel-ZrO2 ceramics w hich had the composition of 55 wt % Al2O3-20 wt % ZrO2-25 wt % MgO, co nsisted of a spinel matrix, whose grain size was in the range of 1.5 t o 2.0 mu m, and uniformly dispersed zirconia agglomerates having grain sizes ranging from 1.0 to 2.0 mu m. Zirconia agglomerates began to ap pear at a temperature of 1500 degrees C and the duplex spinel-ZrO2 str ucture was formed with the weight ratio of Al2O3/MgO being within 1.67 to 2.20 and the amount of ZrO2 addition being within 5 to 25 wt %. Th e relative density, fracture toughness, flexural strength, and critica l temperature difference of the spinel-ZrO2 composite were 97.8 %, 1.9 8 MPam(0.5), 390 MPa, and 275 degrees C, respectively.