Numerical Simulation Of The Planar Potentiometric Oxygen Sensor And Research On Property Of Zirconia Solid Electrolyte

Automobile oxygen sensor is detecting element of EFI engine closed-loop control system and it’s also one of the key components to improve the car engine combustion efficiency, control vehicle emissions and reduce automobile pollution to the environment. At present, planar zirconia oxygen sensors have been the dominating products in the market for their short response time, dependable performance, small size and low manufacturing cost. The structure of the planar potentiometric automobile oxygen sensor and its core component of solid electrolyte were studied. The main research contents are as follows:8YSZ electrolyte nanometer materials composite doped by different ratios of Al2O3 and Bi2O3 nano-powder were prepared by the method of solid state reaction synthesis, dry pressed and pressureless sintered. The density, microstructure, phase and mechanics character of the sintered samples were analyzed by Archimedes principle, SEM, XRD, microhardness tester and universal-testing machine. The results showed that Al2O3 and Bi2O3 sintering additives can reduce the sintering temperature of 8YSZ. Under the same sintering temperature, the relative density of sintered samples increase gradually as Al2O3 content reduce and Bi2O3 content increase. The relative density of sample doped 1%(in mass, the same below) Al2O3 and 4% Bi2O3 sintered at 1300 for 2h reaches the maximum 99.5%. The change trend of the ℃hardness is the same as relative density in the experiment. A small amount of additives Al2O3 and Bi2O3 can improve the bending strength of samples. But when the Bi2O3 content more than 4%, excessive sintering temperature is harmful to the bending strength of samples.A planar potentiometric automobile oxygen sensor employing cerium zirconia oxygen storage material as the solid oxygen partial pressure reference layer was designed. The finite element model of sensor was established. Transient heat transfer analysis and thermal stress analysis on 8YSZ and 3YSZ solid electrolyte respectively were performed. The results of temperature field showed that the sensor had reached response temperature above 300 at ℃t=5s. The temperature of the active area of the sensor is 800 ℃and it also shows good homogeneity in the thickness direction when the sensor is stable. The results of stress field showed that the thermal stress of each layer increases gradually as the temperature rises. When the sensor is stabe the stress reach the maximum but it is less than the fracture strength of each material. The thermal stress of 8YSZ is smaller than its of 3YSZ due to the thermal expansion coefficient of 8YSZ is closer to the sensor material than 3YSZ.