ESTUDO DA ATMOSFERA DE CALCINAÇÃO E DAS TEMPERATURAS DE SINTERIZAÇÃO DE PÓS NANOMÉTRICOS DE ZrO2-Y2O3, E SEUS EFEITOS NAS PROPRIEDADES ELÉTRICAS DE COMPACTOS SINTERIZADOS

Abstract

This work studied the influence of oxidizing atmospheres of calcination and sintering temperature on the electrical properties, densification and grain size of yttria doped with 4.5 mol% zirconia synthesized by a sol-gel process followed by calcination at 600 ºC/2h in O2 and air. Used for uniaxial pressing with pressures between 150 MPa and 1.6 GPa. Sintered by Two Step Sintering (TSS): 1550 °C / 5 min and 1200, 1300, 1400 °C, remaining at these temperatures for 2 and 10 hours. Characterized by X-ray diffraction, apparent density,scanning electron microscopy, impedance spectroscopy. The density measurements were above 94% of theoretical density and grain size between 304 and 477 nm, activation energies of 0.68 and 0.90 eV. The TSS was formed in sintering and grain submicrométicos prevented their excessive growth during the final sintering.The calcination atmosphere had little influence on the values of density and porosity, but caused changes in crystallite size and influenced the values of conductivity