| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas sensor having excellent oxidation resistance in a high temperature environment and capable of suppressing the falling-off of a protector even in an environment in which a cooling-heating cycle occurs.SOLUTION: In a full-region air-fuel ratio sensor 2, a protector 42 is structured of a Fe-Cr alloy material consisting mainly of Fe and containing Si by 2.60 wt.%. Such the Fe-Cr alloy material has a property that a loss of weight due to oxidation hardly occurs even in a high temperature environment of 650°C-900°C. Therefore, the protector 42 excels in oxidation resistance in a high-temperature environment. An absolute value of a difference value between a thermal expansion coefficient α of the protector 42 and a thermal expansion coefficient &bgr; of a housing 38 is 0.4×10[/°C] so a difference in thermal expansion coefficient between the protector 42 and the housing 38 is small. Therefore, occurrence of peeling-off or crack in a junction 43 between the protector 42 and the housing 38 due to a cooling-heating cycle can be prevented. |
