Impact of Sintering Conditions for a Robust Cordierite Ceramic Reinforced with Nano-Silicon Nitride

Abstract

Ceramic-composite materials based on cordierite/nano-silicon nitride (Si3N4) were prepared through the sol-gel route. The sintering process of the green cordierite alone at 1300 and 1400oC forms cordierite and mullite, respectively. Sintering of green cordierite alone with/without Si3N4 at 1350oC provided cordierite and cristobalite in an ambient condition, while in nitrogen condition, it allowed the crystallization of cordierite and Si3N4 phases. The microstructures of the ceramic composites showed irregular or clustered particles containing nano-sized grains of the major cordierite that developed in all the sintered samples at 1350oC. Upon these different sintering temperatures, the bulk densities ranged between 2.255 and 2.305 g/cc in the air and 2.254 and 2.355 g/cc in nitrogen conditions. Moreover, their apparent porosities were between 13 and 17 % in the air and 12.1 and 14 % in nitrogen conditions. The values of bending strength were between 50 and 325 N/mm2. They were higher in the air than in the nitrogen condition.