Synthesis and characterization of a MgO-MgAl2O4-ZrO2 composite with a continuous network microstructure

Using analytically pure MgO, analytically pure Al2O3 and analytically pure ZrO2 as raw materials, Mg4.68Al2.64Zr1.68O12 was prepared at 1993 K for 10 h, and then, a MgO-MgAl2O4-ZrO2 composite with a continuous network was successfully obtained by controlling the cooling rate based on the in-situ decomposition reaction of Mg4.68Al2.64Zr1.68O12 at temperatures below 1887 K. The three phases of MgO, MgAl2O4 and ZrO2 are highly dispersed in this continuous network microstructure, with ZrO2 intertwined by MgO and MgAl2O4 and micropores with a size of less than 2 µm. Furthermore, the synthesis mechanism of Mg4.68Al2.64Zr1.68O12 is given as follows: first, MgAl2O4 is synthesized using the reaction: MgO(s)+Al2O3(s)=MgAl2O4(s) at temperatures below 1894 K; and then, Mg4.68Al2.64Zr1.68O12 is further prepared through MgO and ZrO2 diffusion and dissolution into MgAl2O4 at temperatures above 1894 K, for example, at 1923 K or 1993 K in this work.