Grain Boundary Microcracking in ZrTiO4-Al2TiO5 Ceramics Induced by Thermal Expansion Anisotropy

The grain-boundary microcracking materials in the system $Al_2$TiO$_{5}$ -ZrTiO$_4$(ZAT) is influenced by the thermal expansion anisotropy. The range of ZAT compositions investigated had showed very low thermal expansions of 0.3~1.3$\times$10$^{-6}$ K loin compared to 8.29$\times$10$^{6}$ K of pure ZrTiO$_4$and 0.68$\times$10$^{6}$ K of polycrystalline $Al_2$TiO$_{5}$ , respectively, compared with the theoretical thermal expansion coefficient for a single crystal of $Al_2$TiO$_{5}$ , 9.70$\times$10$^{6}$ K. The low thermal expansion and microcraking temperature are apparently due to a combination of thermal contraction and expansion caused by the large thermal expansion anisotropy of the crystal a ies of the $Al_2$TiO$_{5}$ phase.