摘要 |
A pump cell element, for an air-fuel ratio sensor, comprising an oxygen ion conductive zirconia solid electrolyte, a pair of layer electrodes coated on the both surface areas of a measuring portion, and ceramic coating layers each coated on each of said electrodes, at least one of said coating layers disposed on the electrode of a minus side of the pump cell element being provided uniformly and dispersedly with through-pores having a converted diameter of 20-500 mu m with an average opening percentage of said through-pores is 5-20%. Blackening at the cathode is effectively eliminated.
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