JP2512548B2 - Inspection method of porous protective layer of oxygen sensor - Google Patents

Inspection method of porous protective layer of oxygen sensor

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Publication number
JP2512548B2
JP2512548B2 JP1048091A JP4809189A JP2512548B2 JP 2512548 B2 JP2512548 B2 JP 2512548B2 JP 1048091 A JP1048091 A JP 1048091A JP 4809189 A JP4809189 A JP 4809189A JP 2512548 B2 JP2512548 B2 JP 2512548B2
Authority
JP
Japan
Prior art keywords
oxygen
protective layer
porous protective
oxygen sensor
gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP1048091A
Other languages
Japanese (ja)
Other versions
JPH021534A (en
Inventor
知昭 志村
修一郎 沖
吉彦 水谷
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NGK Insulators Ltd
Original Assignee
NGK Insulators Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NGK Insulators Ltd filed Critical NGK Insulators Ltd
Priority to JP1048091A priority Critical patent/JP2512548B2/en
Priority to DE19893910148 priority patent/DE3910148A1/en
Publication of JPH021534A publication Critical patent/JPH021534A/en
Application granted granted Critical
Publication of JP2512548B2 publication Critical patent/JP2512548B2/en
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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4075—Composition or fabrication of the electrodes and coatings thereon, e.g. catalysts
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4077—Means for protecting the electrolyte or the electrodes

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は酸素濃淡電池式酸素センサの多孔質保護層の
検査方法に関するものである。The present invention relates to a method for inspecting a porous protective layer of an oxygen sensor of an oxygen concentration battery type.

（従来の技術） ZrO2のような酸素イオン伝導性固体電解質の内外両表
面に電極を形成しておき、内外の酸素濃度差を起電力と
して取り出すようにした酸素濃淡電池式酸素センサは、
内燃機関の排ガス中の酸素濃度の検出等に従来から広く
用いられている。一般にこのような酸素センサの電極に
は白金が用いられているが、特に外側の電極は被測定ガ
ス中に晒されるためその外表面に多孔質の保護層が形成
されている。ところがこの保護層が粗で薄い場合には十
分な保護機能が発揮できず、耐久性に劣り、逆に密で厚
い場合には酸素の拡散が阻害されて応答性が劣るため適
正な範囲に設定する必要がある。このため酸素濃淡電池
式酸素センサの製造工程においては、この多孔質保護層
の状態が適正な設定範囲内にあるか否かを検査する必要
がある。(Prior Art) An oxygen concentration cell type oxygen sensor in which electrodes are formed on both the inside and outside surfaces of an oxygen ion conductive solid electrolyte such as ZrO 2 and the oxygen concentration difference between the inside and outside is taken out as an electromotive force is
It has been widely used conventionally for detecting the oxygen concentration in the exhaust gas of an internal combustion engine. Generally, platinum is used as the electrode of such an oxygen sensor, but since the outer electrode is exposed to the gas to be measured, a porous protective layer is formed on the outer surface thereof. However, if this protective layer is rough and thin, it will not be able to exert a sufficient protective function and will be inferior in durability, and conversely if it is dense and thick, oxygen diffusion will be hindered and responsiveness will be inferior, so it will be set to an appropriate range There is a need to. Therefore, in the manufacturing process of the oxygen concentration cell type oxygen sensor, it is necessary to inspect whether or not the state of the porous protective layer is within an appropriate set range.

この目的で従来行われていた検査方法は、多孔質保護
層を切断してその断面を写真撮影し空洞部の面積率を測
定する方法、あるいは水銀を多孔質保護層に圧入しポロ
シティを測定する方法であった。しかしこれらの従来法
は測定誤差が大きいばかりでなく測定値が要求される機
能を直接表現するものではなく、また抜き取り検査しか
行えないという欠点があった。The inspection method conventionally performed for this purpose is to cut the porous protective layer and photograph its cross section to measure the area ratio of the cavity, or to measure the porosity by pressurizing mercury into the porous protective layer. Was the way. However, these conventional methods have the drawbacks that not only the measurement error is large, but also the function that requires the measured value is not directly expressed, and only the sampling inspection can be performed.

（発明が解決しようとする課題） 本発明は上記したような従来の問題点を解決して、多
孔質保護層に要求される特性を直接正確に検査すること
ができ、また工程内検査にも適用することができる酸素
センサの多孔質保護層の検査方法を目的として完成され
たものである。(Problems to be Solved by the Invention) The present invention solves the conventional problems as described above, and can directly and accurately inspect the properties required for the porous protective layer, and also in-process inspection is possible. This is completed for the purpose of an inspection method of a porous protective layer of an applicable oxygen sensor.

（課題を解決するための手段） 本発明は、酸素イオン伝導性固体電解質の、被測定ガ
スに接する外側表面に形成された外側電極と基準ガスに
接する内側表面に形成された内側電極とを備えるととも
に、その外側電極に多孔質保護層を備えた酸素濃淡電池
式酸素センサを、外側の雰囲気を所定の酸素過剰または
酸素不足の状態に保ったまま、外側電極と内側電極との
間に電圧を印加し、限界電流値を測定してその値により
多孔質保護層の良否を判定することを特徴とするもので
ある。(Means for Solving the Problem) The present invention comprises an outer electrode of an oxygen ion conductive solid electrolyte formed on an outer surface in contact with a gas to be measured and an inner electrode formed on an inner surface in contact with a reference gas. At the same time, the oxygen concentration cell type oxygen sensor equipped with a porous protective layer on the outer electrode, while keeping the outer atmosphere in a predetermined excess or deficient state of oxygen, a voltage is applied between the outer electrode and the inner electrode. It is characterized by applying the voltage, measuring the limiting current value, and judging the quality of the porous protective layer based on the measured value.

本発明においては、第１図に示されるように酸素セン
サのZrO2のような酸素イオン伝導性固体電解質（１）の
外側表面に形成された外側電極（２）と内側表面に形成
された内側電極（３）とを直流電源（４）に接続し、該
電極間に抵抗分極による電圧降下分に加えて２ボルト以
下の直流電圧を印加する。このとき、酸素センサの内部
にはヒータ（５）を挿入して600〜800℃程度に加熱して
おくものとする。また外側電極（２）を酸素濃度が一定
で水蒸気またはCO2等の酸素原子を含む気体を混合した
雰囲気中に置くものとする。このように外側の雰囲気中
に水蒸気またはCO2等の酸素原子を含む気体を混合する
のはZrO2磁気の分解を防止するためであって、例えば一
定濃度の酸素を含有したガスを水中に通す等の方法を取
ればよい。上記のようにして酸素センサを加熱しZrO2の
固有抵抗値を下げたうえ、例えば外側の雰囲気を所定の
酸素過剰状態にしたとき、外側電極（２）が−、内側電
極（３）が＋の直流電圧を印加すると、外側電極（２）
とZrO2磁器と酸素ガスの３相が接する３相界面における
酸素ガスO2が酸素イオンO2-に還元されてZrO2磁器内を
移動し、内側にO2として放出される。このとき、外側電
極（２）のある３相界面に十分な酸素ガスO2が存在して
おれば印加電圧とZrO2を流れる電流は直線的関係にある
が、酸素ガスO2が外側電極（２）や多孔質保護層（６）
によって拡散を律速されると、印加する電圧を上げても
電流は増加せず、一定量しか流れない状態が生ずる。こ
の電流を限界電流といい、外側電極（２）及び多孔質保
護層（６）における酸素ガスO2の拡散律速状態を表して
いる。このとき、外側電極（２）は高温度では十分に触
媒能力があり多孔質保護層（６）の1/200〜1/50程度の
厚さを持つにすぎないため、酸素ガスO2の拡散は多孔質
保護層（６）によって律速されることとなり、この状態
における限界電流Ipの値が多孔質保護層（６）の酸素ガ
スO2拡散能力を直接に示すこととなる。しかし、多孔質
保護層の厚さに対して電極の厚さが1/50以上では電極層
の拡散律速も合わせて示す場合があり、この場合は多孔
質保護層の表面から磁器と電極と酸素ガスとの界面、即
ち３相界面までの拡散抵抗を示す。In the present invention, as shown in FIG. 1, an outer electrode (2) formed on the outer surface and an inner surface formed on the inner surface of an oxygen ion conductive solid electrolyte (1) such as ZrO 2 of an oxygen sensor. The electrode (3) is connected to a DC power source (4), and a DC voltage of 2 V or less is applied between the electrodes in addition to the voltage drop due to resistance polarization. At this time, a heater (5) is inserted inside the oxygen sensor to heat it to about 600 to 800 ° C. Further, the outer electrode (2) is placed in an atmosphere having a constant oxygen concentration and mixed with water vapor or a gas containing oxygen atoms such as CO 2 . Mixing the gas containing oxygen atoms such as water vapor or CO 2 in the outside atmosphere in this way is to prevent decomposition of ZrO 2 magnetism, for example, passing a gas containing oxygen at a certain concentration in water. Etc. should be used. As described above, when the oxygen sensor is heated to reduce the specific resistance value of ZrO 2 , and when the outside atmosphere is brought into a predetermined excess oxygen state, the outer electrode (2) is − and the inner electrode (3) is +. Applying a DC voltage to the outer electrode (2)
Oxygen gas O 2 at the three-phase interface where the three phases of ZrO 2 porcelain and oxygen gas are in contact with each other is reduced to oxygen ions O 2 − , moves inside the ZrO 2 porcelain, and is released inside as O 2 . At this time, if sufficient oxygen gas O 2 is present at the three-phase interface with the outer electrode (2), the applied voltage and the current flowing through ZrO 2 have a linear relationship, but the oxygen gas O 2 is 2) and porous protective layer (6)
When the diffusion is rate-controlled by, the current does not increase even if the applied voltage is increased, and a state occurs in which only a fixed amount of current flows. This current is called a limiting current, and represents the rate-determining state of oxygen gas O 2 diffusion in the outer electrode (2) and the porous protective layer (6). At this time, since the outer electrode (2) has a sufficient catalytic ability at a high temperature and has a thickness of about 1/200 to 1/50 of that of the porous protective layer (6), diffusion of oxygen gas O 2 occurs. Is limited by the porous protective layer (6), and the value of the limiting current Ip in this state directly indicates the oxygen gas O 2 diffusing capacity of the porous protective layer (6). However, if the electrode thickness is 1/50 or more of the thickness of the porous protective layer, the diffusion rate control of the electrode layer may also be shown, and in this case, the porcelain, the electrode and the oxygen can be removed from the surface of the porous protective layer. It shows the diffusion resistance up to the interface with gas, that is, the three-phase interface.

第２−１図は上記した電圧と電流の関係を示すグラフ
であって、は多孔質保護層（６）を透過する酸素量が
ZrO2磁器内に移動する酸素量より多い状態、はとは
逆に少ない状態、は水蒸気またはCO2等の混合気体の
分解を示し、またの勾配はZrO2磁器の1/R（R:ZrO2磁
器の固有抵抗）を示す。本発明はこのの状態を利用し
て多孔質保護層（６）の検査を行うものであり、限界電
流Ipの読み取り方法としてはの状態が読み取れればよ
く、例えば第３図に示す２つの方法が考えられる。即
ち、の状態における直線L1との状態における平行な
直線L3との中央の位置に平行な直線L2を引き、この直線
L2がグラフと交わった点Ｐの電流値を限界電流とするＡ
の方法と、この点Ｐにおけるグラフの接線が直線L1と交
わった点Ｑの電流値を限界電流とするＢの方法である。
本発明においてはいずれの方法を採ることもできる。ま
た、本発明はの状態が概ね分っていれば、一定電圧の
印加によって限界電流Ipを読み取っても良い。FIG. 2-1 is a graph showing the relationship between the voltage and the current described above, in which the amount of oxygen passing through the porous protective layer (6) is
ZrO 2 porcelain has more oxygen than it moves, and, conversely, less oxygen, shows decomposition of mixed gas such as water vapor or CO 2 , and the slope of 1 / R (R: ZrO of ZrO 2 porcelain). 2 shows the specific resistance of porcelain). The present invention utilizes this state to inspect the porous protective layer (6), and as a method of reading the limiting current Ip, it is sufficient if the state can be read. For example, two methods shown in FIG. Can be considered. That is, a straight line L 2 is drawn at a central position between the straight line L 1 in the state of and the parallel straight line L 3 in the state of
Limit current is the current value at point P where L 2 intersects the graph A
And the method of B in which the current value at the point Q where the tangent of the graph at this point P intersects the straight line L 1 is the limiting current.
In the present invention, either method can be adopted. Further, in the present invention, if the state of is generally known, the limiting current Ip may be read by applying a constant voltage.

第２−２図は本発明の更なる実施例であって、外側電
極（２）を所定の酸素不足の状態にして、保護層の良否
を検査する場合を示す。酸素不足の状態とはH2、CO、CH
x等の可燃成分を含んだ状態をいう。この状態でははじ
め酸素センサの起電力を生じているが、外側電極に＋、
内側電極に−の直流電圧を印加すると、内側電極とZrO2
磁器と酸素ガスの３相が接する３相界面における酸素ガ
スO2が酸素イオンO2-に還元されて、ZrO2磁器内を移動
し、外側で可燃成分と反応燃焼する。このとき、外側電
極（２）のある３相界面に十分な可燃成分が存在してお
れば印加電圧とZrO2を流れる電流は直線的関係にある
が、可燃成分が外側電極（２）や多孔質保護層（６）に
よって拡散を律速されると、印加する電圧を上げても流
れる電流量が変化せず、一定量となる限界電流値を示
す。この限界電流値を酸素過剰状態の場合と同様な方法
で読み取ることにより、多孔質保護層（６）の拡散抵抗
を測定できる。FIG. 2-2 shows a further embodiment of the present invention, in which the outer electrode (2) is kept in a predetermined oxygen-deficient state and the quality of the protective layer is inspected. Oxygen deficiency states H 2 , CO, CH
A state in which flammable components such as x are included. In this state, the electromotive force of the oxygen sensor is generated first, but +,
When a negative DC voltage is applied to the inner electrode, ZrO 2
Oxygen gas O 2 at the three-phase interface where the three phases of the porcelain and oxygen gas contact each other is reduced to oxygen ions O 2− , moves inside the ZrO 2 porcelain, and reacts and burns with combustible components outside. At this time, if a sufficient combustible component is present at the three-phase interface with the outer electrode (2), the applied voltage and the current flowing through ZrO 2 have a linear relationship, but the combustible component is When the diffusion rate is controlled by the quality protection layer (6), the amount of current flowing does not change even if the applied voltage is increased, and the limit current value becomes a constant amount. The diffusion resistance of the porous protective layer (6) can be measured by reading this limiting current value in the same manner as in the oxygen excess state.

第４図は検査装置の具体例を示すものであり、（10）
は酸素センサ、（11）は酸素センサを加熱するとともに
その外側を一定条件に保つ電気炉であって、例えば空気
量3.5ml/分、N2量2.2l/分の混合ガスが内部に供給され
る。（12）は酸素センサの内部に挿入されたヒータ
（５）のための電源、（13）は電圧発生器である。実際
の測定は標準センサを用い、限界電流Ipが例えば3.9±
0.1mAとなるようにN2量を調整したガスを用いて行う。Fig. 4 shows a concrete example of the inspection device. (10)
Is an oxygen sensor, and (11) is an electric furnace that heats the oxygen sensor and keeps its outside under constant conditions. For example, a mixed gas of air amount 3.5 ml / min and N 2 amount 2.2 l / min is supplied inside. It (12) is a power source for the heater (5) inserted inside the oxygen sensor, and (13) is a voltage generator. The actual measurement uses a standard sensor, and the limiting current Ip is 3.9 ±
It is performed using a gas whose N 2 amount is adjusted to 0.1 mA.

第５図は電気炉（11）の設定炉内温度と電圧−電流曲
線との関係を示すグラフである。炉内設定温度が400℃
（ヒータ（５）が入っているために酸素センサ自体の温
度は500℃）ではZrO2磁器の固有抵抗が高いために限界
電流が読み取れない。炉内設定温度が500℃でも平行直
線が計測しにくいうえ、ZrO2磁器の分解が生ずる電圧以
上となるのでやはり好ましくない。600℃や700℃になる
と計測は容易になり理想的な曲線となるが、高温での測
定は炉やセンサの損傷が大きくなるので、第５図の例で
は600℃程度（酸素センサの温度は710±10℃）が最も適
当である。FIG. 5 is a graph showing the relationship between the set temperature in the electric furnace (11) and the voltage-current curve. Set temperature in furnace is 400 ℃
(The temperature of the oxygen sensor itself is 500 ° C because the heater (5) is installed), so the limiting current cannot be read because the specific resistance of the ZrO 2 porcelain is high. Even if the set temperature in the furnace is 500 ° C, it is not preferable because it is difficult to measure the parallel straight lines and the voltage exceeds the voltage at which the decomposition of the ZrO 2 ceramics occurs. At 600 ° C or 700 ° C, the measurement becomes easy and the curve becomes ideal, but in the case of measurement at high temperature, the damage to the furnace and the sensor becomes large. 710 ± 10 ℃) is the most suitable.

第６図と第７図は酸素センサの外側に流すガス流量と
電圧−電流曲線との関係を示すグラフである。第６図は
N2量を一定に保ち空気量を変化させた例であり、空気量
を増加させれば限界電流値Ipは大となる。第７図は空気
量を一定に保ちN2量を変化させた例であり、N2量を減少
させれば限界電流値Ipは大となる。従ってガス流量のコ
ントロールは厳密に行う必要があり、標準センサを用い
て微調整を行うことが好ましい。いうまでもなく、外側
に流すガスはN2の単純ガスであっても良く、この場合
は、微量のO2含有状態である。6 and 7 are graphs showing the relationship between the gas flow rate flowing outside the oxygen sensor and the voltage-current curve. Figure 6
This is an example in which the amount of N 2 is kept constant and the amount of air is changed. When the amount of air is increased, the limiting current value Ip becomes large. FIG. 7 shows an example in which the amount of air is kept constant and the amount of N 2 is changed. When the amount of N 2 is decreased, the limiting current value Ip becomes large. Therefore, it is necessary to strictly control the gas flow rate, and it is preferable to perform fine adjustment using a standard sensor. Needless to say, the gas flowing to the outside may be a simple gas of N 2 , and in this case, it is in a state of containing a slight amount of O 2 .

このように本発明の方法によれば、限界電流値Ipの大
きさを利用して多孔質保護層（６）の酸素拡散状態を正
確に知ることができ、標準品との対比によって限界電流
Ipの適正な範囲を定めておけば、多孔質保護層（６）の
良否を正確に検査できることとなる。As described above, according to the method of the present invention, the oxygen diffusion state of the porous protective layer (6) can be accurately known by utilizing the magnitude of the limiting current value Ip, and the limiting current value can be compared with the standard product.
If the proper range of Ip is set, the quality of the porous protective layer (6) can be accurately inspected.

（発明の効果） 本発明は以上の説明からも明らかなように、酸素セン
サの多孔質保護層に要求される酸素拡散特性をセンサを
破壊することなく直接正確に検査することができるうえ
に、従来の検査方法とは異なり工程内検査にも適用する
ことができる利点を有する。よって本発明は従来の問題
点を一掃した酸素センサの多孔質保護層の検査方法とし
て、産業の発展に寄与するところは極めて大である。(Effect of the invention) As is apparent from the above description, the present invention can directly and accurately inspect the oxygen diffusion characteristics required for the porous protective layer of the oxygen sensor without destroying the sensor. Unlike the conventional inspection method, it has an advantage that it can be applied to in-process inspection. Therefore, the present invention, as an inspection method for a porous protective layer of an oxygen sensor that eliminates the conventional problems, has a great contribution to industrial development.

【図面の簡単な説明】[Brief description of drawings]

第１図は本発明の検査原理を説明する断面図、第２−１
図及び第２−２図は本発明方法における電圧−電流曲線
のグラフ、第３図は限界電流の読み取り方法を説明する
グラフ、第４図は測定装置の一例を示す回路図、第５図
は種々の温度における電圧−電流曲線のグラフ、第６図
はN2量を一定に保ったまま空気量を変化させた場合の電
圧−電流曲線のグラフ、第７図は空気量を一定に保った
ままN2量を変化させた場合の電圧−電流曲線のグラフで
ある。 （１）：固体電解質、（２）：外側電極、（３）：内側
電極、（６）：多孔質保護層。FIG. 1 is a sectional view for explaining the inspection principle of the present invention, 2-1
2 and 2-2 are graphs of voltage-current curves in the method of the present invention, FIG. 3 is a graph for explaining a method of reading a limiting current, FIG. 4 is a circuit diagram showing an example of a measuring device, and FIG. Graphs of voltage-current curves at various temperatures, Fig. 6 is a graph of voltage-current curves when the amount of air was changed while keeping the amount of N 2 constant, and Fig. 7 kept the amount of air constant. It is a graph of a voltage-current curve when changing the amount of N 2 as it is. (1): solid electrolyte, (2): outer electrode, (3): inner electrode, (6): porous protective layer.

Claims (1)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】酸素イオン伝導性固体電解質の、被測定ガ
スに接する外側表面に形成された外側電極と基準ガスに
接する内側表面に形成された内側電極とを備えるととも
に、その外側電極に多孔質保護層を備えた酸素濃淡電池
式酸素センサを、外側の雰囲気を所定の酸素過剰または
酸素不足の状態に保ったまま、外側電極と内側電極との
間に電圧を印加し、限界電流値を測定してその値により
多孔質保護層の良否を判定することを特徴とする酸素セ
ンサの多孔質保護層の検査方法。1. An oxygen ion conductive solid electrolyte comprising an outer electrode formed on an outer surface in contact with a gas to be measured and an inner electrode formed on an inner surface in contact with a reference gas, the outer electrode being porous. With the oxygen concentration battery type oxygen sensor equipped with a protective layer, a voltage is applied between the outer electrode and the inner electrode while the outer atmosphere is kept in a predetermined excess or deficient state of oxygen, and the limiting current value is measured. Then, a method for inspecting the porous protective layer of the oxygen sensor is characterized by determining the quality of the porous protective layer based on the value.
JP1048091A 1988-03-29 1989-02-28 Inspection method of porous protective layer of oxygen sensor Expired - Lifetime JP2512548B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP1048091A JP2512548B2 (en) 1988-03-29 1989-02-28 Inspection method of porous protective layer of oxygen sensor
DE19893910148 DE3910148A1 (en) 1988-03-29 1989-03-29 Method for testing a porous protective layer of an oxygen sensor

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP7557988 1988-03-29
JP63-75579 1988-03-29
JP1048091A JP2512548B2 (en) 1988-03-29 1989-02-28 Inspection method of porous protective layer of oxygen sensor

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JPH021534A JPH021534A (en) 1990-01-05
JP2512548B2 true JP2512548B2 (en) 1996-07-03

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JP4527580B2 (en) * 2005-03-29 2010-08-18 日本特殊陶業株式会社 Gas sensor evaluation method and gas sensor evaluation apparatus
JP2007232481A (en) * 2006-02-28 2007-09-13 Hitachi Ltd Oxygen sensor
DE102009026418B4 (en) 2009-05-22 2023-07-13 Robert Bosch Gmbh Conditioning of a sensor element in a burner test stand at at least 1000°C and conditioning current

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4088543A (en) * 1976-09-10 1978-05-09 Westinghouse Electric Corp. Technique for protecting sensing electrodes in sulfiding environments
JPH07104319B2 (en) * 1986-09-10 1995-11-13 株式会社日立製作所 Air-fuel ratio sensor

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JPH021534A (en) 1990-01-05
DE3910148A1 (en) 1989-10-19

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