PREPARATION OF NANO AND MICRON SIZED Zr02 DISPERSED Al2O3 CERAMIC COMPOSITES AND STUDY THEIR HARDNESS AND FRACTURE TOUGHNESSES

摘要

The present study aims at improving the fracture toughness of bulk alumina ceramics by incorporating micron and nano sized zirconia particles. Al2O3 - ZrO2 ceramic composites were prepared with 1 vol% micron sized and 1vol% nano sized ZrO2 particles by uniaxial pressing and sintering at 1500°C for soaking time period of 3hr, 6hr and 9hr. The mechanical properties viz. hardness and fracture toughness of the composites were investigated. It was found that the fracture toughness of the nano/micron sized zirconia particle dispersed Al2O3 composites was significantly improved compared to monolithic Al2O3. The alumina composites with 1 vol% nano sized ZrO2 particles sintered at 1500°C for 6hr show highest fracture toughness of 5.76 MPam1'2, while the maximum fracture toughnesses of only alumina and alumina composites with lvol% micron sized ZrO2 particles are 5.29 and 5.35 MPam respectively. The toughening mechanisms of the ceramic composites are discussed.