Preparation of ZnO•2.56Al2O3 Transparent Ceramics by Aqueous Gelcasting and Hot Isostatic Pressing

Zinc-aluminum spinel transparent ceramics are typical multi-functional materials with excellent optical, thermal and dielectric properties. ZnAl2O3-Al(2)O(3)ceramics green body were fabricated through aqueous gelcasting forming technique starting from the raw materials of ZnAl2O4 and Al2O3. The stable slurries of ZnAl2O4-Al2O3 with 50vol% solids loading were prepared. Furthermore, the effects of the dispersant, pH value and solid loading on the rheological properties were systematically investigated. Then, gel-casted green compacts were pressureless sintered and hot isostatic pressed to obtain transparent ceramics. Finally, transparent ZnO center dot 2.56Al(2)O(3) ceramics (1.8 mm in thickness) with in-line transmittance value of 70% in visible region and higher than 80% in infrared region were obtained. The samples exhibited Vickers hardness of (11.34 +/- 0.17) GPa, Young's modulus of 285 GPa.