| 摘要 |
PURPOSE:To improve voltage and current characteristics of the element of an oxygen concentration sensor by making the size of the cathode smaller than the size of the plane that forms the cathode of an oxygen ion conductive body and increasing the contact face between the porous layer and the oxygen ion conductive body. CONSTITUTION:A cathod 8 and anode 9 that are smaller than an oxygen ion conductive body 7 are formed by spattering of platinum at the center between the upper and lower faces of the oxygen ion conductive body 7. On the surface of the cathode 8 a porous layer 10 of 640mum thickness is formed by plasma spray coating that uses as the raw material spinel type powder. Because the cathod 8 is made smaller than the oxygen ion conductive body 7 and formed with the porous layer, the distance in which the porous layer 10 and the oxygen ion conductive body 7 are directly joined becomes large with the result of enlarged upper limit of measurement of oxygen concentration. For elements with this construction, further, the porous layer 10 is made more dense in the center than in the periphery in order to reduce oxygen gas that flows in parallel to the cathede face, and the residual are residual not dense area is made to contact with the atmosphere that is measured. With this arrangement, the characteristics of the oxygen concentration sensor is improved. |
