工作温度对ZrO_2基NO_x传感器泵电流影响测试分析

Test and analysis about effect of operating temperature on pump current of ZrO_2-based NO_x sensor

为探究工作温度对ZrO_2基NO_x传感器泵电流信号影响,优化控制其工作温度,采用单泵法测量不同工作温度下ZrO_2基NO_x传感器中主泵、辅助泵和测量泵的泵电流,对各泵电流曲线进行分析,并与推导出的温度与泵电流理论关联式比较。实验结果表明,主泵泵电流与温度的关系与理论关系一致,而辅助泵和测量泵泵电流和温度的关系与理论关系有所偏差。辅助泵中扩散通道结构较复杂,使得曲线斜率呈增大趋势;测量泵中活化电极含有Pt、Rh元素,高温下Rh有氧化增重现象,同时考虑基体二氧化锆高温导电性能,使得曲线斜率呈先增大后减小趋势。综合来看,比较合理的工作温度范围为1 003.15～1 063.15 K,从而可以在温控良好的情况下进一步自主研发出具有良好工作性能的NO_x传感器。

To explore the influence of operating temperature to the pump current signal in ZrO2-based NOx sensorand to optimize the operating temperature, single-pump method is taken to measure the pump current of main pump, auxiliary pump and measuring pump in ZrO2-based NOx sensor under different operating temperatures, analyze the pump current curve, and compare with the deduced theoretical correlation of temperature and pump current. Experimental result shows that the relationship between the main pump current and temperature is in accordance with the theory, but the relationships between the current of auxiliary pump as well as measuring pump and temperature deviate from the theoretical relationship. The structure of the diffusion channel in the auxiliary pump is more complicated, which makes the slope of the curve increase;The active electrode in the measuring pump contains Pt and Rh elements, there is an oxidized weight gain of Rh at high temperature, and consider the high-temperature conductivity of the matrix zirconia, the slope of the curve increases at first and then decreases.Taken together, a more reasonable operating temperature range is 1 003.15-1 063.15 K, which can be in the case of good temperature control to further develop a good working performance of the NOx sensor.