Poisoning of Zirconia Exhaust Oxygen Sensors by Silica

The performance of Zirconia Exhaust Oxygen Sensors can be altered by several poisons. Silica produced by the oxidation of volatile silicones is one of the most severe poisons and can affect both the exhaust side of the sensor and the air reference side. This paper presents an overview of the subject of silica poisoning including field observations of silica poisoning, the mechanism of the poisoning, test techniques to evaluate silicone bearing materials and sensor poisoning sensitivity. Some data on improving resistance to poisoning is also presented.