Optimization of sintering parameters for fabrication of Al2O3/TiN/TiC micro-nano-composite ceramic tool material based on microstructure evolution simulation

Abstract

In order to design and fabricate a new Al2O3/TiC/TiN micro-nano-composite ceramic tool material with high mechanical properties, a microstructure evolution model of ceramic tool material during sintering process was established to optimize the sintering parameters based on cellular automata. Furthermore, the effects of TiC nano-particles on mechanical properties of the prepared material were investigated. Toughening and strengthening mechanisms of TiC nano-particles were revealed by examining SEM images of microstructure and crack propagation. The results indicated that the mechanical properties increased first and then decreased as TiC nano-particles volume fractions of prepared material rose. When Al2O3, TiC, TiN micro-particles and TiC nano-particles were 60%, 20%, 10% and 10%, respectively, ceramic material prepared exhibited outstanding mechanical properties with Vickers hardness of 20.8 GPa, flexure strength of 881.4 MPa, and fracture toughness of 7.8 MPa m1/2 obtained at the sintering temperature of 1650 °C with holding time for15min through the simulation. The main strengthening and toughening mechanisms of the prepared materials could be attributed to transgranular fracture, intergranular fracture, crack deflection and crack bridging.