Effect of protective layer on response characteristics of automobile exhaust gas oxgen sensor

A protective layer coating on the electrode of potentiometric oxygen sensor in automobile is commonly used to clean exhaust gas.Influences of the preparation procedure and the material of the protective layer on output voltage,lifetime and response time of the potentiometric oxygen sensor have been thoroughly investigated.The experimental results show that there are huge differences between the measured values and the realistic values for the output voltage of the potentiometric oxygen sensor when the materials of 20 % mass fraction silica gel is used to fabricate the protective layer can react with sensor's electrode material or electrolyte material.The lifetime of the protective layer can be enhanced by adding some YSZ powder into the protective layer.Response times of the potentiometric oxygen sensor are closely related to the physical parameters(thickness and pore size)of the protective layer and sensor's working temperature.