SOL-GEL SYNTHESIS OF NANOPHASE YTTRIA-STABILIZED TETRAGONAL ZIRCONIA AND DENSIFICATION BEHAVIOR BELOW 1600-K

The hot-pressing behavior of nanophase, 3-mol%-yttria-stabilized, tetr agonal zirconia (Y-TZP) was studied in the temperature range 1290 to 1 570 K. Powder was sol-gel synthesized using zirconium tetrachloride an d hydrated yttrium chloride precursors. After drying and calcination, the particle size was 40 nm, coarsening to 70 nm upon subsequent annea ling at 1273 K. On compact heating at 23-MPa applied stress, densifica tion initiated near the calcination/annealing temperature. Theoretical density was obtained at densification temperature above 1490 K with p article coarsening consistent with classical coarsening kinetics. Micr ostructural change accompanying densification involved formation of de nse regions 2 to 4 mum in size separated by irregularly shaped porous regions. The observed densification behavior complements calculated de nsification maps for fine-particle Y-TZP.