| 摘要 |
PROBLEM TO BE SOLVED: To provide an oxygen sensor element capable of surely preventing poisoning from an exhaust gas to keep stable electrode performance over a long time. SOLUTION: This oxygen sensor is composed by forming a reference electrode 3 and a measurement electrode 4 in at least opposite positions on the inside and outside surfaces of a zirconia solid electrolyte substrate 2. A porous ceramic protection layer 13 formed of magnesia alumina spinel is formed on the surface of the measurement electrode 4, and the composition of the magnesia alumina spinel is set more alumina-rich than a stoichiometric composition ratio. |
