Study On Properties And Application Of Yttria Stabilized Zirconia Solid State Electrolyte

Zirconia is a very important ceramic material and has been widely used in the oxygen-sensing technology, so improving the performance of zirconia solid electrolyte has important significance for the development of oxygen-sensing technology. But pure zirconia is hardly conductive, so it is often choose yttria-doped as stabilizer, samples that different of yttrium oxide content are the varies greatly for performances, the5YSZ (5mol%Y2O3yttria-stabilized zirconia) and8YSZ (8mol%Y2O3yttria-stabilized zirconia) powders are prepared by hydrolysis,5YSZ and8YSZ ceramic samples are prepared by different calcination temperatures (900℃,1000℃,1100℃,1200℃) and sintering temperature (1400℃,1450℃,1500℃,1550℃).The granularity, microstructure,phase composition, electrical properties and mechanical properties of samples are analyzed by laser particle size analyzer, scanning electron microscopy (SEM), X-ray diffraction (XRD), AC impedance spectroscopy(LCR) and other testing methods, the best sintering process is explored,the5YSZ and8YSZ prepared by the optimum calcination temperature and sintering temperature are used in oxygen pumps and automotive oxygen sensor, The conclusions are as follows:(1) The optimum calcination temperatures of the5YSZ and8YSZ powders prepared are at1100℃and1000℃respectively, optimum sintering temperatures are1500℃,the optimum sintering temperatures both are1500℃.The samples that prepared by the optimum calcination and sintering are relatively dense, porosity small and optimal mechanical properties. The particle size and narrow particle size distribution of the5YSZ powder prepared by hydrolysis method are smaller than that of the powders prepared by solid-phase and co-precipitation method, and comply with criteria of powder selection, the density and mechanical properties of samples are better than samples of other methods. (2) The impedances are tested at different temperatures,with increasing of the temperatures, the grain conductivity,the grain boundary conductivity and total conductivity are increase. As the grain size of the sample increases, the grains conductivity of5YSZ are gradually increased,but the grains conductivity of8YSZ are decreased. For grain boundary conductivity,the grain boundary layers of5YSZ and8YSZ are thickens that lead to grain boundary resistance increases and the conductivity decreased, with increasing of grain size of5YSZ, grain boundary conductivity greater contribution to the total conductivity, total conductivity of8YSZ is the same trend with grain and the grain boundary conductivity.(3) Considering mechanical and electrical properties of5YSZ and8YSZ, The powder of8YSZ is better electrical properties,it is prepared zirconia oxygen pump tube and assembly into the oxygen pump,the oxygen experiments is studied by the oxygen pump. The powder of5YSZ is better the mechanical properties than8YSZ, so5YSZ was prepared as automobile oxygen sensor, the response time is studied.