The Research Of The High-performance YSZ-based Mixed-potential-type NO₂ Sensor Using For Automobile

This paper focuses on the gas sensing properties of YSZ-based mixed-potential-type NO₂ sensor using for automobile. High-performance three-phase boundary was attained by sand-blasting technology which could generate porous structure on YSZ-substrate. The sensing performance was also enhanced by new-type sensitive electrode materials. The research includes three aspects:Firstly, to fabric high-performance three-phase boundary, sand-blasting technology was applied to process the YSZ-substrate by different size of carborundum（Si C）. The roughness tester and scanning electron microscope showed that both surface roughness of YSZ substrate and the performance of the sensor increased with the increasing of Si C sand diameter. The sensor using the YSZ-substrate processed by 80 μm Si C gave the largest signal to NO₂ at 850°C, and its sensitivity was 58mv/decade.Secondly, the sensing characteristics of the sensors were enhanced by new sensitive electrode materials which were synthesized by sol-gel method. The experiment result indicates the sensor using In₂O₃ sensing electrode mixed with 5% Mo O₃ shows large sensitivity（59 m V/decade） and good stable and repeatable performance at elevated temperature.At last, by the measurement of complex impedance and the anodic and cathodic polarization curve of the device, the evidence for the mixed-potential potential theory was supplied.In conclusion, this thesis provides new method to enhance the performance of YSZ-based mixed-potential-type NO₂ sensor using for automobile by the construction of high-performance three-phase-boundary and the development of new sensitive electrode materials, and it optimizes the detection to NO₂.