Preparation And Oxygen Sensitive Properties Of Co-doped ZrO₂ Materials

With the widely using of industrial boilers and automobiles, the research of yttrium stabled zirconium (YSZ) materials with high ionic conductivity and quick-sreaction capability as oxygen sensor is developed. In this paper, zirconium dioxide ceramics was investigated in both preparation technology and oxygen sensitivity. The properties of the nano-powder and the sintering behaviors were investigated systematically. The mechanics of preparation and the oxygen sensitivity were studied.First, YSZ powders with different amount of Al₂O₃ and Sc₂O₃ doped were prepared by coprecipitation method using zirconium oxychloride and yttrium oxide as raw material. The phase composition and particle size distribution of powder were characterized by TG-DSC, XRD and TEM. The effects of factors such as temperature during precipitation, addition of dispersant agent, pH value and calcining temperature were studied. The results indicated that the YSZ powders with great sintering behaviors and low agglomerated structure were prepared with the precipitation temperature of 40°C-50°C, dispersant agent addition of 4% mass percent, pH value of 9-11 and calcining temperature of 800°C. The particle size of powder samples was around 15nm. The sintering performance was greatly ameliorated by spray pelleting method. The small and homogeneous pores in the green body could be easily eliminated as the size distribution of the powders prepared by spray pelletization method was homogeneous. The density of the sample sintered at 1500°C for 4 h was 5.92g/cm³.The powder was then mechanically pressed into pellets and sintered at 1450°C-1550°C for 2-4 h. The ionic conductivity and oxygen sensitivity of the samples with platinum electrode were measured. The surface of the sintered body was observed by SEM. The effects of different amount of Al₂O₃ and Sc₂O₃ doping were investigated. The results showed that the grain boundary was cleaned as the reaction of doping Al₂O₃ and the SiO₂ impurity in the raw material. Both the sintering process and the density were improved by the liquid phase reaction. The density of the 8YSZ doped with 1% mol Al₂O₃ reached 6.01g/cm³ after sintering at 1450°C for 4 h. At the test temperature of 700°C, the conductivity of 1Al-8YSZ sample was 4.6×10^-3S·cm^-1 and the experimental potential were approximated to theoretic potential according to...