The effect of sintering temperature and low content of TiO2 on the microstructure and mechanical properties of ZTA-TiO2 composites

ZTA composites have very attractive properties that make them useful in various critical applications such as armor and medical technologies. High sintering temperatures are required to densify these materials, and some additives are used to lower the sintering temperature and increase the physical properties to make these materials more convenient. In this study, TiO2 addition was performed in low contents (0.1, 0.3, 1.0wt%) to ZTA by pressureless sintering at 1600 degrees C and 1650 degrees C, separately. The effect of TiO2 addition on the mechanical properties (elastic modulus, hardness, and fracture strength) of ZTA was evaluated depending on the densification and microstructure. Higher densification was obtained for the composites sintered at 1650 degrees C, and the existence of TiO2 can promote the sinterability of ZTA for 0.1 and 0.3wt% at 1600 degrees C. The matrix grain size increased with TiO2 addition. The microstructure has changed with the formation of rod-like Al2TiO5 and coarse ZrTiO4 secondary phases. The highest hardness of 19.5 GPa was obtained for ZTA sintered at 1650 degrees C with the highest densification and elastic modulus. The highest fracture strength value was obtained for 0.1wt% TiO2-containing ZTA sintered at 1600 degrees C as 323 MPa because of the lower Al2O3 grain size and higher relative density than ZTA sintered at 1600 degrees C. The outcomes reveal that ZTA containing 0.1wt% TiO2 sintered at 1600 degrees C may be an alternative material to ZTA in critical structural applications where specific gravity is important because of its high fracture strength in addition moderate elastic modulus and hardness values.