Low thermal expansion behavior and thermal durability of ZrTiO4–Al2TiO5–Fe2O3 ceramics between 750 and 1400 °C

The thermal-shock-resistant materials in the system Al2TiO5–ZrTiO4 (ZAT) were synthesized by oxide process. The range of ZAT compositions investigated had showed very low thermal expansions of 0.3∼1.3×10−6/K compared to 8.29×10−6/K of pure ZrTiO4 and 0.68×10−6/K of polycrystalline Al2TiO5, respectively, compared with the theoretical thermal expansion coefficient for a single crystal of Al2TiO5, 9.70×10−6/K. The composites also had high thermal durability between 750 and 1400° for 100 h. The low thermal expansion and high thermal durability are apparently due to a combination of microcracking caused by the large thermal expansion anisotropy of the crystal axes of the Al2TiO5 phase and the limitation of grain growth Al2TiO5 by the ZrTiO4. The microstructural degradation of the composites is presented here analyzed by scanning electron microscopy, X-ray diffraction, and dilatometry.