| 摘要 |
PURPOSE:To activate the catalytic action of platinum and to enhance the low- temperature characteristic of the title sensor by a method wherein Rh or Pd as an auxiliary catalyst is added to an electrode material in which platinum has been mixed with a ceramic. CONSTITUTION:Platinum electrodes 2, 3 are formed respectively on the inner surface and the outer surface of a zirconia tube 1 which is formed of zirconia and whose tip is closed. A platinum catalyst layer 4 and a protective layer 5 are formed on the outer surface of the tube 1. A reference gas is introduced into the inside space of the tube 1, the outside of the tube 1 is brought into contact with a gas under test, an electromotive force according to the ratio of oxygen partial pressures at the inside and the outside is generated across the electrodes 2, 3, and the oxygen concentration of the gas under test is detected. A mixture of platinum and a ceramic which form the electrodes 2, 3 is constituted at a mixture ratio of 60 to 80% of the platinum to 20 to 40% of the ceramic. In addition, at least one out of Rh and Pd is used as an auxiliary catalyst. Its addition amount is 0.5 to 5wt.% of a solid portion (platinum + ceramic). |
