INFLUENCE OF SEEDING ON THE CRYSTALLIZATION KINETICS OF AIR-CALCINED Y-TZP GEL-DERIVED PRECURSORS

Yttria-doped tetragonal zirconia (Y-TZP, 3 mol% Y2O3) amorphous precur sors seeded with nanometric Y-TZP particles (5 to 10 wt%) were prepare d by the sol-precipitation method. Solid-state reactions occurring dur ing heating were studied by differential thermal analysis and X-ray di ffraction. It was found that the seeding of Y-TZP amorphous precursors with 5 to 10 wt% crystalline Y-TZP nanometric particles considerably lowered the onset of the Y-TZP solid solution crystallization temperat ure by nucleation and epitaxial growth. Thus, a complete Y-TZP solid s olution was formed in the temperature range of 320-350 degrees C in ai r after a heat treatment for 20 h. The seeded Y-TZP precursors exhibit ed enhanced crystallization kinetics (about one order of magnitude hig her), and the activation energy for the Y-TZP solid solution crystalli zation was reduced from 184 to 119 kJ/mol. (C) 1997 Elsevier Science L td.