The reaction mechanism analysis and mechanical properties of large-size Al2O3/ZrO2 eutectic ceramics prepared by a novel combustion synthesis. Issue 11 (1st August 2018) - Yu, Wanjun
Abstract: Large-size Al2 O3 /ZrO2 eutectic ceramics (Φ53 × 75 mm) were successfully fabricated based on the exothermic reaction between Al and Zr(NO3 )4 via a novel combustion synthesis under low pressure. The reaction mechanism was analyzed using the thermodynamics method. In the reaction process, the intermediate products of AlN were partially converted into ZrN phase, and the remaining AlN phase decomposed into nitrogen. The Al2 O3 /ZrO2 composite materials with 85.74 vol% eutectic were obtained with the mole ratio of ZrO2 :Al2 O3 reached 0.9:1. The rod-like ZrO2 phase with a diameter ~ 268 nm was in-situ embedded in Al2 O3 phase; the average eutectic interspacing is ~ 183 nm, and the average width of grain boundary is 520 nm. The hardness and fracture toughness of Al2 O3 /ZrO2 eutectic ceramics are 17.8 GPa and 10.6 MPa m 1/2, respectively. The excellent mechanical properties are ascribed to the fine microstructure and special phase composition.