Investigation of mechanical properties of Al2O3/ZrO2 ceramic composites prepared with different additives

Due to their superior properties, ZTA composites are used in critical applications such as armor. High sintering temperature and addition of reinforcement materials are required to increase densification and obtain optimum mechanical properties in ZTA. In this study, the composites were sintered separately at 1600 and 1650°C by adding TiO2 (0.1%; 0.3; 1) at low ratios to the ZTA . A high densification was obtained for the samples sintered at 1650°C. The matrix grain size increased with the addition of TiO2. The microstructure was changed with the rod like Al2TiO5 and ZrTiO4. A high hardness value of 19.5 GPa was obtained for the ZTA sintered at 1650°C. A high flexural strength value of 323 MPa due to low grain size and high densification was obtained for the 0.1% TiO2 added ZTA sintered at 1600°C. The effect of Cr2O3 addition in different powder sizes on the densification and mechanical properties of ZTA was also investigated. Nano and micron size Cr2O3 powder in different weight ratios (0.3; 0.6; 1) was added to the ZTA separately and after dry pressing, sintering was carried out in air at 1650°C/2 h. For composites containing Cr2O3, the relative density values were close to each other. A slight decrease was observed in both densification and elastic modulus due to the evaporation of Cr2O3. In the composite containing 0.6% Cr2O3 prepared with micron size powder, 7% increase in strength was obtained compared to the ZTA due to the compressive stresses at the grain boundaries generated solid solution formation. Key Words : ZTA composites, ceramic armors, titanium dioxide, chromium oxide, microstructure, mechanical properties