| 摘要 |
PURPOSE:To improve the sensor characteristic of the oxygen sensor by providing a porous protective layer having a reference and measurement electrodes on the surface of an solid oxygen ion conducting electrolyte and using a heat-resisting metal oxide on the surfaces of the electrodes on the side on which a gas to be measured is brought into contact with the electrodes and mixing a composite oxide of zirconium oxide and cerium oxide in the electrodes. CONSTITUTION:Air is introduced to the inside of a solid oxygen ion conducting electrolyte 2 as a reference oxygen concentration and a gas to be measured is made to flow to the outside of the electrolyte 2. A porous reference and measuring electrodes 3 and 4 made of platinum, etc., are respectively formed on the internal and external surfaces of the tubular electrolyte 2. The electrodes 3 and 4 are formed by applying or printing paste composed mainly of platinum powder mixed with fine ceramic particles of a composite oxide obtained by mixing zirconium oxide and cerium oxide at a mole ratio (%) of 90:10 to 70:30 as an electrode material and baking the paste. A porous protective layer 5 is formed on the electrode 4 at the part of the sensor 1 which is brought into contact with the gas to be measured and, in addition, a catalyst layer 6 is provided when required. This sensor has an excellent heat resistance and thermal stability and exerts an excellent sensor characteristic at a low temperature. |
