JPH0820404B2 - Oxygen sensor element - Google Patents
Oxygen sensor elementInfo
- Publication number
- JPH0820404B2 JPH0820404B2 JP63008447A JP844788A JPH0820404B2 JP H0820404 B2 JPH0820404 B2 JP H0820404B2 JP 63008447 A JP63008447 A JP 63008447A JP 844788 A JP844788 A JP 844788A JP H0820404 B2 JPH0820404 B2 JP H0820404B2
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- Prior art keywords
- electrode
- thickness
- oxygen sensor
- sensor element
- layer
- Prior art date
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- Measuring Oxygen Concentration In Cells (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） この発明は、酸素センサ素子の改良に関し、特にガス
応答性および低温作動性の向上を図った電極構造を有す
る酸素センサ素子に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an oxygen sensor element, and more particularly to an oxygen sensor element having an electrode structure with improved gas responsiveness and low temperature operability.
（従来の技術） 従来、酸素イオン導電性の固体電解質を用い、酸素濃
淡電池の原理により、内燃機関等から排出される排気ガ
ス中の酸素濃度を測定するものとしていわゆる酸素セン
サが知られている。(Prior Art) Conventionally, a so-called oxygen sensor has been known as a device for measuring the oxygen concentration in exhaust gas discharged from an internal combustion engine or the like by the principle of an oxygen concentration battery using an oxygen ion conductive solid electrolyte. .
かかる酸素センサに使用される酸素センサ素子として
は、例えば有底円筒状のイットリア添加ジルコニア磁器
等を酸素イオン導電性の固体電解質として、この固体電
解質の内外面に、例えば白金等の電極を付与したものが
一般的であり、内面の電極を大気と連通させて基準酸素
濃度の電極とする一方、外面の電極を被測定ガスである
排気ガス中に曝して測定電極とすることによって排ガス
中の酸素濃度を測定するしくみになっている。As an oxygen sensor element used in such an oxygen sensor, for example, a bottomed cylindrical yttria-doped zirconia porcelain or the like is used as an oxygen ion conductive solid electrolyte, and electrodes such as platinum are provided on the inner and outer surfaces of the solid electrolyte. Oxygen in the exhaust gas is obtained by exposing the inner electrode to the measurement gas by exposing it to the exhaust gas that is the gas to be measured, while the inner electrode communicates with the atmosphere to form the reference oxygen concentration electrode. It is a mechanism to measure the concentration.
（発明が解決しようとする問題点） しかしながら、かかる電極は、その厚さが数μｍ程度
と薄いが、皮膜状となっているため、そのままではガス
透過性が悪く、そのため応答性が悪い。この応答性を良
くするために加熱する方法もあるが、白金等の電極が焼
結してしまい、低温作動性が低下する欠点がある。(Problems to be Solved by the Invention) However, although such an electrode has a thin thickness of about several μm, since it is in the form of a film, the gas permeability is poor as it is, and therefore the response is poor. There is a method of heating to improve the responsiveness, but there is a drawback that the electrode such as platinum is sintered and the low temperature operability is deteriorated.
この発明は、上記した欠点を解消し、測定電極のガス
透過性を適度に高め、低温作動性を改善し、同時にガス
応答性を向上させた酸素センサ素子を提供することを目
的とする。It is an object of the present invention to solve the above-mentioned drawbacks, to appropriately increase the gas permeability of the measurement electrode, to improve the low temperature operability, and at the same time to provide an oxygen sensor element having an improved gas responsiveness.
（問題点を解決するための手段） すなわちこの発明は、酸素イオン導電性固体電解質よ
りなる基体上の所定箇所に電極層が形成された酸素セン
サ素子において、前記電極層の表面の電極材料結晶の平
均粒径が、電極層の厚さの0.1倍以上乃至5.0倍以下であ
り、かつ2.5μｍ以下であるとともに、前記電極層の膜
厚が0.5〜5.0μｍであることを特徴とする。(Means for Solving Problems) That is, the present invention relates to an oxygen sensor element in which an electrode layer is formed at a predetermined position on a substrate made of an oxygen ion conductive solid electrolyte, and an electrode material crystal on the surface of the electrode layer The average particle diameter is 0.1 to 5.0 times the thickness of the electrode layer and 2.5 μm or less, and the thickness of the electrode layer is 0.5 to 5.0 μm.
（作 用） 本発明では、電極層の表面の電極材料結晶の平均粒径
を適性範囲内に制御することにより、電極材料の粒子間
すなわち粒界が非常に長く形成され、同時に空孔が形成
され易くなり、これらのため電極表面積が増大し、触媒
活性が高くなり、そして低温作動性および応答性を改善
することができるのである。(Operation) In the present invention, by controlling the average particle size of the electrode material crystals on the surface of the electrode layer within an appropriate range, the interparticles of the electrode material, that is, the grain boundaries, are formed to be very long, and at the same time pores are formed. Which can increase the surface area of the electrode, increase the catalytic activity, and improve low temperature operability and responsiveness.
また、この電極材料結晶の平均粒径が比較的小さいこ
とから、酸素センサ素子の高温作動中における結晶粒子
の粒成長がおこりにくく、これが電極層の焼結による低
温作動性の劣化を防止する役目を果たす。Further, since the average grain size of the electrode material crystals is relatively small, grain growth of crystal grains during the high temperature operation of the oxygen sensor element is unlikely to occur, which serves to prevent deterioration of low temperature operability due to sintering of the electrode layer. Fulfill.
この平均粒径の範囲は、電極の粒径／層厚の比をとる
と、0.1〜5.0、好ましくは0.2〜3.0の間であると良好な
低温作動性が得られる。When the ratio of the average particle diameter to the particle diameter / layer thickness of the electrode is 0.1 to 5.0, preferably 0.2 to 3.0, good low temperature operability is obtained.
ところで、電極材料結晶の平均粒径は2.5μｍ以下が
好ましく、平均粒径が2.5μｍを超えると電極の表面積
が小さくなり、低温作動性に影響を与えると考えられ
る。By the way, the average grain size of the electrode material crystals is preferably 2.5 μm or less, and when the average grain size exceeds 2.5 μm, the surface area of the electrode becomes small, which is considered to affect the low temperature operability.
以下、この発明を具体的に説明する。 The present invention will be specifically described below.
この発明にかかる固体電解質としては、酸素イオン導
電性を有するものであれば何でもよいが、例えばYb2O3,
Sc2O3,CaO,MgO,ThO2,CeO2等を添加したZrO2;CaO,La2O3
等を添加したCeO2;Er2O3,SrO等を添加したBi2O3;あるい
はY2O3等を添加したThO2その他があり、特にY2O3等を含
むZrO2（完全安定および部分安定を含む）が好ましい。The solid electrolyte according to the present invention may be any as long as it has oxygen ion conductivity, for example Yb 2 O 3 ,
Sc 2 O 3 , CaO, MgO, ThO 2 , CeO 2 etc. added ZrO 2 ; CaO, La 2 O 3
Such as CeO 2 ; Er 2 O 3 , SrO etc. added Bi 2 O 3 ;, Y 2 O 3 etc added ThO 2 etc., especially ZrO 2 containing Y 2 O 3 etc. And partially stable) are preferred.
上記固体電解質より形成された固体電解質素子の形状に
ついては、排気ガスに接する外表面に凹凸層を設けた有
底円筒状がとりわけ有利に適用する。詳細については、
本出願人が先に提案した実公昭61−8359号公報に記載さ
れているため、説明を省略する。As for the shape of the solid electrolyte element formed of the solid electrolyte, a bottomed cylindrical shape having an uneven layer on the outer surface in contact with exhaust gas is particularly advantageously applied. For more information,
The description is omitted because it is described in Japanese Utility Model Publication No. 61-8359 previously proposed by the applicant.
ここにおいて固体電解質素子の排気ガスに接する外表
面に凹凸層が設けてあると、たとえば電極材料付与方法
としての無電解めっき処理時に水素ガスが発生し、水素
ガスが凹凸の谷部に停滞することにより、その部分がめ
っきされず空孔となり易いため、結果的にめっき層の表
面積が増大するので有利である。Here, if an uneven layer is provided on the outer surface of the solid electrolyte element in contact with exhaust gas, hydrogen gas is generated during electroless plating as a method for applying an electrode material, for example, and hydrogen gas stays in the valleys of the unevenness. Thus, that portion is not plated and is likely to be a void, and as a result, the surface area of the plated layer is increased, which is advantageous.
電極材料としては、白金属金属、特に白金がその触媒
性ゆえに好ましい。As an electrode material, a white metal metal, particularly platinum is preferable because of its catalytic property.
さて上記したような、有底円筒状の固体電解質素子の
内外表面に金属層を形成して電極とするわけであるが、
この発明ではかかる電極の付与を、例えば無電解めっき
によって行う。Now, as described above, a metal layer is formed on the inner and outer surfaces of a bottomed cylindrical solid electrolyte element to form an electrode.
In the present invention, the application of such electrodes is performed by, for example, electroless plating.
ここにめっき浴としては、白金めっき浴が有利であ
り、白金めっき浴の場合は、Ptとして、0.1〜5.0g/含
むものを適宜選択して使用する。Here, a platinum plating bath is advantageous as the plating bath, and in the case of the platinum plating bath, Pt containing 0.1 to 5.0 g / is appropriately selected and used.
そして上記したごとき、めっき浴（15〜35℃）中に９
〜20時間程度浸漬させておくことによって、0.5〜5.0μ
ｍ程度の厚みのめっき層が得られる。この場合に、めっ
き層即ち電極の厚みを上記範囲に限定したのは、厚み0.
5μｍ以下であると実際の被測定雰囲気中における酸素
センサ素子の作動中に電極材料が減耗して、電気的導通
状態になり易く、耐久性が悪いためであり、また0.5μ
ｍより薄い電極では被測定ガスが電極を透過するパスが
短すぎるため十分に未燃焼成分の反応が進まず、低温作
動性が劣る傾向があるためである。厚みが5.0μｍ以上
を超えると、熱処理をしても電極表面積を増大し、ガス
透過性を良くする空孔が発生しにくくなり、また熱処理
条件をきびしくして空孔を発生させようとすると電極金
属粒が大きく焼結しすぎてしまうためである。この厚み
のより最適な範囲としては0.7〜1.5μｍ程度が好まし
い。Then, as described above, 9 in the plating bath (15-35 ° C)
0.5 ~ 5.0μ by soaking for ~ 20 hours
A plating layer having a thickness of about m can be obtained. In this case, the thickness of the plating layer, that is, the electrode is limited to the above range, the thickness 0.
This is because when the thickness is 5 μm or less, the electrode material is worn out during the operation of the oxygen sensor element in the actual atmosphere to be measured, and the electrical conductivity is likely to occur, and the durability is poor.
This is because the electrode thinner than m has a too short path for the gas to be measured to pass through the electrode, so that the reaction of unburned components does not proceed sufficiently and the low temperature operability tends to be poor. If the thickness exceeds 5.0 μm, the surface area of the electrode will increase even after heat treatment, and it will be difficult for pores that improve gas permeability to be generated. Also, if the heat treatment conditions are strict and pores are to be generated, the This is because the metal particles are excessively sintered too much. The more optimal range of this thickness is preferably about 0.7 to 1.5 μm.
また、電極の厚みと、電極材料結晶との関係は、粒形
状によっても異なってくるが、電極の層厚に対し電極の
粒径（即ち電極の粒径／層厚）を0.1〜5.0倍程度にする
と良い。The relationship between the electrode thickness and the crystal of the electrode material varies depending on the particle shape, but the particle size of the electrode (that is, the particle size of the electrode / layer thickness) is about 0.1 to 5.0 times the layer thickness of the electrode. It is good to
上記のようなめっき処理後、水洗さらには湯洗のよう
な洗浄処理を施した後、乾燥処理を経てから、大気中ま
たはCOガスを含む還元性ガス雰囲気中にて熱処理を施
す。After the plating treatment as described above, a washing treatment such as a water washing and a hot water washing is performed, and after a drying treatment, a heat treatment is performed in the atmosphere or a reducing gas atmosphere containing CO gas.
一方、COガスを含む還元性ガス雰囲気中での熱処理
は、めっき材料としてのPtの結晶粒成長を抑制しつつ、
結晶粒子の間の粒界及び空孔を生じさせ、めっき層の表
面積が増大する効果がある。On the other hand, the heat treatment in a reducing gas atmosphere containing CO gas suppresses the growth of Pt crystal grains as a plating material,
There is an effect that grain boundaries and vacancies are generated between the crystal grains and the surface area of the plating layer is increased.
かくして固体電解質素子の表面に、ガス透過性の良い
かつ表面積の大きい電極が形成されるので、ガス応答性
の早い、低温作動性の良い、かつ耐久性の良い酸素セン
サ素子が得られるのである。Thus, an electrode having a good gas permeability and a large surface area is formed on the surface of the solid electrolyte element, so that an oxygen sensor element having a high gas responsiveness, a good low temperature operability, and a good durability can be obtained.
さらにかような熱処理の後、電極表面の保護のため
に、スピネル粒子のプラズマ溶射を施し、スピネルコー
ト層を形成するのは従来と同様である。After such heat treatment, spinel particles are plasma-sprayed to protect the electrode surface, and a spinel coat layer is formed in the same manner as in the prior art.
（実施例） 本発明の実施例を図面に基づき説明する。(Example) An example of the present invention will be described with reference to the drawings.
実施例１ まず、第１図に示すような有底円筒状（ｕ＝50mm,m＝
9mm,n＝6mm,0＝4mm,先端部肉厚0.7mm）の、排ガスに曝
されるべき領域の表面に、約50μｍの凹凸層を有するY2
O3が添加された安定化ジルコニア磁器製の固体電解質素
子を、その表面の汚れを取り除くために脱脂処理をした
後、フッ酸等の酸でエッチング処理を行い、次いで白金
として0.2g/含み、白金無電解めっきの析出速度およ
び液組成を調整しためっき浴中に浸漬し、７時間保持し
た。この結果、厚さが約1.0μｍのめっき層を得た。こ
のめっき層が施された固体電解質素子を流水中でよく洗
浄した後、120℃で１時間かけて乾燥した。最後にめっ
き層を固体電解質の下地に密着させるため、85℃の還元
性雰囲気中で10時間かけて熱処理をした。こののち、固
体電解質素子即ち酸素センサ素子の、外面電極の太径部
からの下方の部分に、ハウジングに接する部分を除い
て、MgAl2O4スピネルコーティングを厚さ100μｍで付与
した。さらに再び温度850℃のCO20％を含む還元性雰囲
気中にて熱処理を施した。Example 1 First, a cylindrical shape with a bottom (u = 50 mm, m =
9 mm, n = 6 mm, 0 = 4 mm, tip wall thickness 0.7 mm) Y 2 with an uneven layer of about 50 μm on the surface of the area to be exposed to exhaust gas
O 3 is added to the solid electrolyte element made of stabilized zirconia porcelain, after degreasing treatment to remove stains on the surface, etching treatment with an acid such as hydrofluoric acid, then 0.2g / platinum as contained, The platinum electroless plating was immersed in a plating bath in which the deposition rate and the liquid composition were adjusted and kept for 7 hours. As a result, a plating layer having a thickness of about 1.0 μm was obtained. The solid electrolyte element provided with this plating layer was thoroughly washed in running water and then dried at 120 ° C. for 1 hour. Finally, in order to bring the plated layer into close contact with the base of the solid electrolyte, heat treatment was performed in a reducing atmosphere at 85 ° C for 10 hours. After that, a MgAl 2 O 4 spinel coating having a thickness of 100 μm was applied to a portion of the solid electrolyte element, that is, the oxygen sensor element, below the large diameter portion of the outer surface electrode except for a portion in contact with the housing. Further, heat treatment was performed again in a reducing atmosphere containing 20% CO at a temperature of 850 ° C.
また、めっき浴条件、めっき温度、熱処理条件を調節
して膜厚および電極金属粒子径を種々変化させた電極を
有する酸素センサ阻止を多数得た。In addition, many oxygen sensor inhibitions having electrodes with various thickness and electrode metal particle diameters were obtained by adjusting the plating bath conditions, plating temperature, and heat treatment conditions.
このようにして得られた酸素センサ素子の電極表面を
走査型電子顕微鏡（SEM）にて観察するとともに、電子
顕微鏡写真を複数個撮影し、この写真に任意に引いた線
分比を測長して電極層の平均粒径を求めた。この測長法
は金属材料検査法における線分析法と称されている。The electrode surface of the oxygen sensor element thus obtained was observed with a scanning electron microscope (SEM), a plurality of electron microscope photographs were taken, and the line segment ratio arbitrarily drawn on this photograph was measured. The average particle size of the electrode layer was determined by This length measuring method is called a line analysis method in the metal material inspection method.
次に、第２図に示すように酸素センサ素子11にハウジ
ング13を装着し、電気的接続を行う。まず、得られた酸
素センサ素子11を、ハウジング13の段付部15にタルク等
の封止剤17により固定する。外側電極19をハウジング13
と電気的に接触させて、このハウジング13を介して外部
へ電気的に接続する。内側電極21を中心電極23を経て酸
素センサ素子外部の信号検出回路へ接続する。Next, as shown in FIG. 2, the housing 13 is attached to the oxygen sensor element 11 and electrically connected. First, the obtained oxygen sensor element 11 is fixed to the stepped portion 15 of the housing 13 with a sealant 17 such as talc. Outer electrode 19 housing 13
, And is electrically connected to the outside through the housing 13. The inner electrode 21 is connected to the signal detection circuit outside the oxygen sensor element via the center electrode 23.
このように構成された酸素センサについて以下の特
性、即ち応答性おび低温作動性についての評価試験を行
った。ただし、評価試験のために、この酸素センサを、
自動車のエンジンの直後の排気管に取り付けて、最高温
度1000℃までの排気ガス中の酸素分圧を測定している。The oxygen sensor thus constructed was evaluated for the following characteristics, that is, responsiveness and low temperature operability. However, for the evaluation test, this oxygen sensor,
It is attached to the exhaust pipe immediately after the engine of an automobile and measures the oxygen partial pressure in the exhaust gas up to a maximum temperature of 1000 ° C.
（応答性測定） 排気量1500ccの４気筒ガソリンエンジンの外部のエン
ジン制御用のコンピュータによって、排気ガス温度を35
0℃に維持しつつ、排気ガス中の空燃比を切り換えて、
切り換え後のセンサ出力が変化するフィードバック周波
数（Hz）を夫々測定した。したがって、フィードバック
周波数が高いほど応答性が良好である。(Responsiveness measurement) Exhaust gas temperature is controlled by a computer for external engine control of a 4-cylinder gasoline engine with a displacement of 1500cc
While maintaining at 0 ℃, switch the air-fuel ratio in the exhaust gas,
The feedback frequency (Hz) at which the sensor output changed after switching was measured. Therefore, the higher the feedback frequency, the better the response.
（低温作動性測定） 同様に、排気量1500ccのエンジンの排気ガス温度450
℃から、センサ出力が微弱となり、フィードバック制御
が停止状態になる温度まで、排ガス温度を低下させ、そ
の停止状態時の排気ガス温度を測定した。したがって、
測定値が低いほど低温作動性が良好になる。(Low-temperature operability measurement) Similarly, the exhaust gas temperature of an engine with a displacement of 1500cc is 450.
The exhaust gas temperature was lowered from 0 ° C to a temperature at which the sensor output became weak and the feedback control stopped, and the exhaust gas temperature in the stopped state was measured. Therefore,
The lower the measured value, the better the low temperature operability.
以上の測定結果を第３図のグラフ図にて示す。ここに
おけるグラフ図において、横軸に白金電極表面の平均粒
径（μｍ）をとり、左右の縦軸に低温作動性（℃）（図
中において符号ａの実線で示す）および応答性（Hz）
（図中において符号ｂの実線で示す）を夫々プロットし
ている。The above measurement results are shown in the graph of FIG. In this graph, the horizontal axis represents the average particle size (μm) on the platinum electrode surface, and the left and right vertical axes represent the low temperature operability (° C) (shown by the solid line a in the figure) and response (Hz).
(Indicated by a solid line of reference numeral b in the figure) are plotted.
第３図から分かるように、電極材料結晶の平均粒径が
約2.5μｍ以下であると、応答性および低温作動性の良
好な酸素センサ素子が得られる。As can be seen from FIG. 3, when the average grain size of the electrode material crystals is about 2.5 μm or less, an oxygen sensor element having excellent responsiveness and low temperature operability can be obtained.
実施例２ 試料１ 白金粉末として、球形状の、平均粒径0.3μｍのもの
を使用した。この粉末に、有機溶剤、有機バインダおよ
び分散剤を添加して粘度を調整して白金ペーストを作製
した。続いて、Y2O36mol％添加ジルコニア磁器製の、有
底円筒状の、予めエッチング処理が施してある固体電解
質素子の内外表面に、上述した白金ペーストを塗布し
た。塗布厚は、３〜５μｍとした。塗布後、120℃で15
分間乾燥した後、ベルト炉において800℃で５分間焼き
付け処理を行った。その後、400℃の水素ガス中で30分
間かけて活性化処理を施した。Example 2 Sample 1 A platinum powder having a spherical shape and an average particle size of 0.3 μm was used. An organic solvent, an organic binder, and a dispersant were added to this powder to adjust the viscosity, to prepare a platinum paste. Subsequently, the above-mentioned platinum paste was applied to the inner and outer surfaces of a bottomed cylindrical solid electrolyte element made of zirconia porcelain containing Y 2 O 3 6 mol% and having been subjected to etching treatment in advance. The coating thickness was 3 to 5 μm. 15 at 120 ° C after application
After drying for a minute, a baking process was performed at 800 ° C. for 5 minutes in a belt furnace. After that, activation treatment was performed in hydrogen gas at 400 ° C. for 30 minutes.
得られためっき層即ち電極層の厚さは、平均2.5μｍ
であり、線分析法にて観察した電極表面における白金粒
子の平均粒径は0.7μｍであった。The thickness of the obtained plating layer or electrode layer is 2.5 μm on average.
The average particle size of the platinum particles on the electrode surface observed by the line analysis method was 0.7 μm.
試料２ と同様に白金粉末に、平均粒径1.0μｍ（平板を球
形に換算した粒径値）の、平板状の、ロジウム粉末を10
wt％添加して、試料１と同様に内外表面に３〜５μｍ厚
で塗布し、乾燥後、焼き付け処理を行った。最後に前述
と同様にして活性化処理を実施した。In the same manner as in Sample 2, 10 pieces of flat rhodium powder with an average particle diameter of 1.0 μm (particle diameter value obtained by converting a flat plate into a spherical shape) was added to platinum powder.
wt% was added and applied to the inner and outer surfaces in a thickness of 3 to 5 μm as in Sample 1, dried and then baked. Finally, the activation process was performed in the same manner as described above.
得られためっき層即ち電極層の厚さは平均2.0μｍで
あり、線分析法にて観察した電極表面における金属粒子
の平均粒径は0.5μｍであった。The thickness of the obtained plating layer, that is, the electrode layer was 2.0 μm on average, and the average particle size of the metal particles on the electrode surface observed by the line analysis method was 0.5 μm.
試料３ 白金粉末として平均直径0.1μｍ、長さ１〜２μｍの
線状の粉末を使用した。この粉末に、有機溶剤、有機バ
インダおよび分散剤を添加して粘度を調整して、白金ペ
ーストを作製した。続いて、Y2O36mol％添加したジルコ
ニア磁器製の有底円筒状の、予めエッチング処理が施し
てある固体電解質素子の内外表面に、上述した白金ペー
ストを塗布した。これも塗布厚は３〜５μｍとした。塗
布後、120℃で15分間乾燥した後、ベルト炉において800
℃で10分間焼き付け処理を施した。その後温度700℃のC
O＋H2ガス中で１時間かけて活性化処理を施した。Sample 3 As the platinum powder, a linear powder having an average diameter of 0.1 μm and a length of 1 to 2 μm was used. An organic solvent, an organic binder and a dispersant were added to this powder to adjust the viscosity, and a platinum paste was produced. Subsequently, the above-mentioned platinum paste was applied to the inner and outer surfaces of a bottomed cylindrical solid electrolyte element made of zirconia porcelain to which Y 2 O 3 6 mol% was added and which was previously subjected to etching treatment. The coating thickness was also 3 to 5 μm. After coating, dry at 120 ° C for 15 minutes and then 800 in a belt furnace.
A baking process was performed at 10 ° C. for 10 minutes. Then the temperature of 700 ℃ C
The activation treatment was performed in O + H 2 gas for 1 hour.
得られた電極層の厚さは、平均1.3μｍであり、線分
析法にて観察した電極表面における白金粒子の平均粒径
は2.5μｍであった。The thickness of the obtained electrode layer was 1.3 μm on average, and the average particle size of platinum particles on the electrode surface observed by the line analysis method was 2.5 μm.
その他の試料については、上記した試料１〜３の作製
条件を変えて、その電極の厚さを0.5〜5.0μｍの範囲、
および白金粒子の平均粒径を0.3〜2.5μｍの範囲で変化
させたものを作製した。このため、これらを以下に試料
１系、試料２系および試料３系と称することとする。For other samples, the production conditions of Samples 1 to 3 described above were changed, and the thickness of the electrode was changed to 0.5 to 5.0 μm.
Also, platinum particles having different average particle diameters in the range of 0.3 to 2.5 μm were prepared. Therefore, these are hereinafter referred to as Sample 1 system, Sample 2 system and Sample 3 system.
このように構成された酸素センサ素子の試料について
低温作動性についての評価試験を行った。この低温作動
性の測定については、前述した実施例１に説明してある
ので、説明は省略する。この結果を第４図に示す。この
図中において、横軸は電極の層厚に対する電極の粒径
（即ち電極の粒径／層厚）をとり、縦軸に低温作動性
（℃）をプロットした。さらに試料１系は実線で、試料
２系は一点鎖線で、試料３系は点線でそれぞれ示してい
る。さらに実施例１で調整した試料については太い実線
でしめす。An evaluation test for low-temperature operability was performed on the sample of the oxygen sensor element thus configured. Since the measurement of the low temperature operability has been described in the above-mentioned Example 1, the description thereof will be omitted. The results are shown in FIG. In this figure, the horizontal axis represents the particle size of the electrode with respect to the electrode layer thickness (that is, the particle size of the electrode / layer thickness), and the vertical axis plots the low temperature operability (° C). Further, the sample 1 system is shown by a solid line, the sample 2 system is shown by a chain line, and the sample 3 system is shown by a dotted line. Furthermore, the sample prepared in Example 1 is shown by a thick solid line.
第４図から分かるように、電極の粒径／層厚が0.1〜
5.0の間、好ましくは0.2〜3.0の間で良好な低温作動性
を示している。なお、電極の粒径が細かい領域で低温作
動性が悪くなる傾向があるのは、粒径が細かくなり過ぎ
て各粒子間に形成されるべき空孔が少なくなるか、また
は殆ど無くなるため、応答性が悪くなり、これが低温作
動性に影響したものと考えられる。As can be seen from FIG. 4, the electrode particle size / layer thickness is 0.1 to
It exhibits a good low temperature workability between 5.0, preferably between 0.2 and 3.0. Note that the low temperature operability tends to deteriorate in the region where the particle size of the electrode is small, because the particle size becomes too fine and the number of pores that should be formed between each particle decreases, or there is almost no response. It is thought that this deteriorated the workability, which affected the low temperature operability.
（発明の効果） 以上の説明から明らかなように、本発明は、酸素セン
サ素子の電極を所定の平均粒径としたため、電極の表面
積を増大し、これがため、低温作動性および応答性を良
好なものとする。(Effects of the Invention) As is apparent from the above description, in the present invention, since the electrode of the oxygen sensor element has a predetermined average particle diameter, the surface area of the electrode is increased, which results in good low temperature operability and responsiveness. It should be
第１図は本発明の酸素センサ素子の一例を示す一部断面
側面図、 第２図は酸素センサ素子をハウジングに組み込んだ様子
を示す一部断面側面図、 第３図は実施例１において電極の結晶粒径に対する低温
作動性および応答性特性を示すグラフ図、 第４図は実施例１および実施例２において電極の粒径／
層厚に対する低温作動性を示すグラフ図である。 11……酸素センサ素子、13……ハウジング 15……段付部、17……封止部 19……外側電極、21……内側電極 23……中心電極1 is a partial sectional side view showing an example of the oxygen sensor element of the present invention, FIG. 2 is a partial sectional side view showing a state in which the oxygen sensor element is incorporated in a housing, and FIG. 3 is an electrode in Example 1. Fig. 4 is a graph showing low temperature operability and response characteristics with respect to the crystal grain size of Fig. 4, and Fig. 4 shows the grain size of the electrode in Example 1 and Example 2
It is a graph which shows low temperature operability with respect to layer thickness. 11 …… Oxygen sensor element, 13 …… Housing 15 …… Stepped part, 17 …… Sealed part 19 …… Outer electrode, 21 …… Inner electrode 23 …… Center electrode
Claims (1)
上の所定箇所に電極層が形成された酸素センサ素子にお
いて、前記電極層の表面の電極材料結晶の平均粒径が、
電極層の厚さの0.1倍以上乃至5.0倍以下であり、かつ2.
5μｍ以下であるとともに、前記電極層の膜厚が0.5〜5.
0μｍであることを特徴とする酸素センサ素子。1. An oxygen sensor element having an electrode layer formed at a predetermined location on a substrate made of an oxygen ion conductive solid electrolyte, wherein the average particle size of electrode material crystals on the surface of the electrode layer is:
0.1 times to 5.0 times the thickness of the electrode layer, and 2.
The thickness of the electrode layer is 0.5 μm or less, and the thickness of the electrode layer is 0.5 to 5.
An oxygen sensor element having a thickness of 0 μm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63008447A JPH0820404B2 (en) | 1988-01-20 | 1988-01-20 | Oxygen sensor element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63008447A JPH0820404B2 (en) | 1988-01-20 | 1988-01-20 | Oxygen sensor element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01185440A JPH01185440A (en) | 1989-07-25 |
| JPH0820404B2 true JPH0820404B2 (en) | 1996-03-04 |
Family
ID=11693380
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63008447A Expired - Lifetime JPH0820404B2 (en) | 1988-01-20 | 1988-01-20 | Oxygen sensor element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0820404B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9134268B2 (en) | 2011-06-20 | 2015-09-15 | Toyota Jidosha Kabushiki Kaisha | Manufacturing method for oxygen sensor |
| US9437999B2 (en) | 2011-08-10 | 2016-09-06 | Toyota Jidosha Kabushiki Kaisha | Method for manufacturing oxygen sensor |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4637375B2 (en) * | 2001-01-31 | 2011-02-23 | 京セラ株式会社 | Manufacturing method of oxygen sensor |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59109855A (en) * | 1982-12-16 | 1984-06-25 | Mazda Motor Corp | Manufacture of wide-range air fuel ratio sensor |
| JPS59142457A (en) * | 1983-02-03 | 1984-08-15 | Mazda Motor Corp | Production of wide range air-fuel ratio sensor |
-
1988
- 1988-01-20 JP JP63008447A patent/JPH0820404B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9134268B2 (en) | 2011-06-20 | 2015-09-15 | Toyota Jidosha Kabushiki Kaisha | Manufacturing method for oxygen sensor |
| US9437999B2 (en) | 2011-08-10 | 2016-09-06 | Toyota Jidosha Kabushiki Kaisha | Method for manufacturing oxygen sensor |
| DE112012003280B4 (en) * | 2011-08-10 | 2017-03-09 | Toyota Jidosha Kabushiki Kaisha | Method for producing an oxygen sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01185440A (en) | 1989-07-25 |
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