ZrO_2氧传感器电极保护层的模拟

Modeling of the Electrode Protecting Coating on ZrO_2 Oxygen Sensor

汽车尾气净化用ZrO2 气体氧传感器的外电极表面常有陶瓷多孔层 ,用含有一个扩散孔的致密陶瓷构件 (扩散障 )模拟该陶瓷多孔层。测量了带扩散障的ZrO2 气体氧传感器的伏安曲线 ,并对该伏安曲线进行解析和数学模拟。发现氧气在扩散孔中扩散受阻时引起了电极极化 ,其极化程度与直流电流大小、温度、扩散孔几何尺寸、氧气的浓度等有关。给出了相应的数学表达式 ,其模拟伏安曲线与实际测量结果能较好的吻合。

A porous ceramic coating the electrode of zirconia oxygen sensor is commonly used to clean exhaust gas from cars. The coating is modeled as a kind of gas diffusion barrier with a small hole in a dense ceramic block. The V/I characteristics of the sensor with the diffusion barrier is measured, resolved and simulated. Slow diffusion of oxygen gas in the small hole results in electrode polarization. A mathematic model is proposed. The modeling V/I characteristics fit the realistic V/I characteristics very well.