INSPECTION OF POROUS PROTECTIVE LAYER OF OXYGEN SENSOR

摘要

PURPOSE:To enable direct and exact inspection without breaking the sensor by impressing a voltage between an outer electrode and an inner electrode while the atmosphere on the outer side is maintained in a prescribed oxygen excess state and measuring the limit current value, then passing judgment. CONSTITUTION:The outer electrode 2 formed on the outside surface of a solid electrolyte 1 such as oxygen sensor ZrO2 and the inner electrode 3 formed on the inside surface are connected to a DC power supply 4 and the DC voltage as much as the voltage drop by resistance polarization plus <=2V is impressed between the two electrodes 2 and 3. A heater 5 is inserted into the oxygen sensor and the sensor is previously heated to about 600-800 deg.C at this time. The outer electrode 2 is placed in the atmosphere in which the oxygen concn. is constant and which is mixed with a gas such as steam contg. oxygen atoms. The O2 of the 3 phase boundary where the outer electrode 2 comes into contact with ZrO2 magnetism is reduced and moved and is released into the inner electrode 3 when the DC voltage is impressed to the electrodes.