JPH06160333A - Manufacture of oxygen sensor - Google Patents
Manufacture of oxygen sensorInfo
- Publication number
- JPH06160333A JPH06160333A JP43A JP30853092A JPH06160333A JP H06160333 A JPH06160333 A JP H06160333A JP 43 A JP43 A JP 43A JP 30853092 A JP30853092 A JP 30853092A JP H06160333 A JPH06160333 A JP H06160333A
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- paste
- oxygen sensor
- oxygen
- platinum
- 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.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は酸素センサの製造方法に
関し、詳しくは、酸素分圧比に応じた起電力を発生する
酸素センサにおいて、初期応答性及び低温活性を向上さ
せ、また、耐久性に優れた酸素センサを提供するための
技術に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an oxygen sensor, and more specifically, in an oxygen sensor that generates an electromotive force according to an oxygen partial pressure ratio, it improves initial responsiveness and low temperature activity, and also improves durability. The present invention relates to a technique for providing an excellent oxygen sensor.
【０００２】[0002]
【従来の技術】従来、酸素イオン伝導性固体電解質を用
いた酸素センサとしては、例えば以下に示すようなセン
サ部構造を有したものがある（特開昭５８−２０４３６
５号公報、実開昭５９−３１０５４号公報等参照）。即
ち、酸化ジルコニウムＺｒＯ2 を主成分とする酸素イオ
ン伝導性固体電解質から形成される先端が閉塞されたジ
ルコニアチューブの内表面及び外表面にそれぞれ白金Ｐ
ｔ電極を形成すると共に、外側の白金Ｐｔ電極の更に外
側に多孔セラミックス保護層を形成する。2. Description of the Related Art Conventionally, as an oxygen sensor using an oxygen ion conductive solid electrolyte, there is one having a sensor part structure as shown below (Japanese Patent Laid-Open No. 58-20436).
No. 5, Japanese Utility Model Publication No. 59-31054, etc.). That is, platinum P is formed on the inner surface and the outer surface of a zirconia tube having a closed tip formed of an oxygen ion conductive solid electrolyte containing zirconium oxide ZrO 2 as a main component.
A t-electrode is formed, and a porous ceramics protective layer is formed further outside the platinum Pt electrode on the outside.
【０００３】かかる構成において、ジルコニアチューブ
の内側空洞に基準気体（例えば大気）を導入する一方、
ジルコニアチューブの外側を被検出気体（例えば内燃機
関の排気）と接触させ、内表面に接触する基準気体の酸
素分圧と、外表面に接触する被検出気体の酸素分圧との
比に応じた起電力を、前記電極間に発生させることによ
って、被検出気体の酸素分圧（酸素濃度）を検出するも
のである。In such a structure, while a reference gas (for example, the atmosphere) is introduced into the inner cavity of the zirconia tube,
The outside of the zirconia tube is brought into contact with the gas to be detected (for example, exhaust gas from an internal combustion engine), and the oxygen partial pressure of the reference gas that contacts the inner surface and the oxygen partial pressure of the gas that contacts the outer surface are determined according to the ratio. By generating an electromotive force between the electrodes, the oxygen partial pressure (oxygen concentration) of the gas to be detected is detected.
【０００４】[0004]
【発明が解決しようとする課題】ところで、前記電極の
形成方法としては、真空蒸着法，無電解めっき法，ペー
スト法などが用いられている。前記真空蒸着法，無電解
めっき法は、焼結後のジルコニアチューブに付着させる
ために高い熱負荷が加わることがなく触媒活性及び応答
特性が良好であるが、付着強度が弱いために電極剥離や
特性変化が大きく、耐久性が悪い。By the way, as a method of forming the electrode, a vacuum deposition method, an electroless plating method, a paste method and the like are used. The vacuum deposition method and the electroless plating method have good catalytic activity and response characteristics without being subjected to a high heat load because they are attached to the zirconia tube after sintering, but because of weak adhesion strength, electrode peeling or The characteristics change greatly and the durability is poor.
【０００５】一方、ペースト法は、電極材をペースト状
にして仮焼状態のジルコニアチューブに塗布してから焼
結させる法であり、同時焼結によりジルコニアチューブ
に対する付着強度が強く、耐久性に優れるという利点が
ある。しかしながら、製造段階で高い熱履歴にさらされ
ることになるため、電極の触媒活性が悪いという欠点を
有する。このため、耐久性を確保するためにペースト法
で電極を形成させる場合には、ヒータを内蔵させて低温
活性の向上を図っていた。On the other hand, the paste method is a method in which an electrode material is made into a paste and applied to a calcined zirconia tube and then sintered, and the co-sintering gives a strong adhesion strength to the zirconia tube and is excellent in durability. There is an advantage. However, since it is exposed to a high thermal history in the manufacturing stage, it has a drawback that the catalytic activity of the electrode is poor. Therefore, when the electrodes are formed by the paste method in order to secure the durability, a heater is built in to improve the low temperature activity.
【０００６】しかしながら、ヒータを設けることによっ
て酸素センサのコストアップを招き、また、ヒータ電圧
がリークした場合に素子が破壊される惧れがあるなどの
問題が新たに発生していた。本発明は上記問題点に鑑み
なされたものであり、耐久性を確保しつつ電極の触媒活
性を向上させ得る酸素センサの製造方法を提供し、以
て、酸素センサの低温作動化を改善することを目的とす
る。However, the provision of the heater causes a cost increase of the oxygen sensor, and there is a new problem that the element may be destroyed when the heater voltage leaks. The present invention has been made in view of the above problems, and provides a method for manufacturing an oxygen sensor capable of improving the catalytic activity of an electrode while ensuring durability, thereby improving the low temperature operation of the oxygen sensor. With the goal.
【０００７】[0007]
【課題を解決するための手段】そのため本発明では、酸
素イオン伝導性固体電解質からなる基体の内外表面に電
極をそれぞれ形成し、基準気体に接触させた一方表面の
電極と、被検出気体に接触させた他方表面の電極との間
に酸素分圧比に応じた起電力を発生する酸素センサの製
造方法であって、主成分の白金ＰｔにロジウムＲｈとパ
ラジウムＰｄとの少なくとも一方を添加した貴金属ペー
ストに、セラミックスを添加してなる電極材ペースト
を、仮焼き状態の前記基体に塗布した後、前記電極材と
基体とを同時焼結させるようにした。Therefore, in the present invention, an electrode is formed on each of the inner and outer surfaces of a substrate made of an oxygen ion conductive solid electrolyte, and the electrode on one surface is brought into contact with a reference gas and the gas to be detected is brought into contact with the reference gas. A method of manufacturing an oxygen sensor for generating an electromotive force according to an oxygen partial pressure ratio between the electrode on the other surface and a noble metal paste in which at least one of rhodium Rh and palladium Pd is added to platinum Pt as a main component. After the electrode material paste obtained by adding ceramics to the base material in the calcined state was applied, the electrode material and the base material were simultaneously sintered.
【０００８】[0008]
【作用】上記製造方法によると、まず、酸素イオン伝導
性固体電解質からなる基体と電極とを同時焼結させるか
ら、電極の付着強度が強く耐久性に優れた酸素センサを
提供できる。また、白金Ｐｔを主成分とする貴金属ペー
ストに、ロジウムＲｈとパラジウムＰｄとの少なくとも
一方が添加され、このロジウムＲｈとパラジウムＰｄ添
加によって白金Ｐｔの触媒活性，応答が改善される。According to the above-described manufacturing method, first, the substrate made of the oxygen ion conductive solid electrolyte and the electrode are simultaneously sintered, so that an oxygen sensor having a strong electrode adhesion strength and excellent durability can be provided. Further, at least one of rhodium Rh and palladium Pd is added to a noble metal paste containing platinum Pt as a main component, and the addition of rhodium Rh and palladium Pd improves the catalytic activity and response of platinum Pt.
【０００９】[0009]
【実施例】以下に本発明の実施例を説明する。実施例の
酸素センサ構造を示す図１において、酸化ジルコニウム
ＺｒＯ2 を主成分とする酸素イオン伝導性固体電解質か
ら形成される先端が閉塞されたジルコニアチューブ１
（基体）の内表面及び外表面にそれぞれ起電力取り出し
用の電極２，３が形成されている。EXAMPLES Examples of the present invention will be described below. Referring to FIG. 1 showing an oxygen sensor structure of an example, a zirconia tube 1 having a closed tip formed of an oxygen ion conductive solid electrolyte containing zirconium oxide ZrO 2 as a main component.
Electrodes 2 and 3 for extracting electromotive force are formed on the inner surface and the outer surface of the (base), respectively.
【００１０】また、前記外表面側の電極３の外側には、
該電極３を保護するための多孔質のセラミックス保護層
４が形成されている。かかる構成において、ジルコニア
チューブ１の内側空洞に基準気体（例えば大気）を導入
する一方、ジルコニアチューブ１の外側を被検出気体
（例えば内燃機関の排気）と接触させ、内表面に接触す
る基準気体の酸素分圧と、外表面に接触する被検出気体
の酸素分圧との比に応じた起電力を、前記電極２，３間
に発生させることによって、被検出気体の酸素分圧（酸
素濃度）を検出し得るものである。On the outside of the electrode 3 on the outer surface side,
A porous ceramic protective layer 4 for protecting the electrode 3 is formed. In such a configuration, while the reference gas (for example, the atmosphere) is introduced into the inner cavity of the zirconia tube 1, the outside of the zirconia tube 1 is brought into contact with the gas to be detected (for example, the exhaust gas of the internal combustion engine), and the reference gas that comes into contact with the inner surface is The oxygen partial pressure (oxygen concentration) of the gas to be detected is generated by generating an electromotive force according to the ratio of the oxygen partial pressure and the oxygen partial pressure of the gas to be detected in contact with the outer surface between the electrodes 2 and 3. Can be detected.
【００１１】ここで、上記構成の酸素センサは以下のよ
うにして製造される。まず、ジルコニアチューブ１を作
製し、これを一旦仮焼きする。一方、セラミックス粉を
添加した貴金属ペースト（電極材ペースト）を作製す
る。ここで、前記貴金属ペーストは、白金Ｐｔを主成分
とし、該白金Ｐｔに対して0.5 〜50wt％（重量パーセン
ト）の割合で、ロジウムＲｈとパラジウムＰｄとの少な
くと一方を添加したものである。また、前記セラミック
ス粉は、ジルコニアとイットリアとを９：１程度の割合
で混合させたものであり、貴金属成分に対して10〜40wt
％程度添加される。Here, the oxygen sensor having the above structure is manufactured as follows. First, the zirconia tube 1 is produced and is temporarily calcined. On the other hand, a precious metal paste (electrode material paste) to which ceramic powder is added is prepared. Here, the precious metal paste contains platinum Pt as a main component, and at least one of rhodium Rh and palladium Pd is added to the platinum Pt at a rate of 0.5 to 50 wt% (weight percent). The ceramic powder is a mixture of zirconia and yttria in a ratio of about 9: 1, and is 10 to 40 wt% with respect to the noble metal component.
% Is added.
【００１２】次いで、前記貴金属ペーストを、印刷によ
ってジルコニアチューブ１に１〜50μｍ程度の厚さに塗
布した後、貴金属ペーストとジルコニアチューブ１とを
1100〜1300℃程度の高温で同時に焼結させることで、ジ
ルコニアチューブ１の表面に電極を形成する。尚、貴金
属ペーストをジルコニアチューブ１に塗布する方法とし
ては、上記の印刷の他、ディッピング，刷毛塗り，スプ
レー噴射などがあるが、特に印刷が好ましい。Next, the precious metal paste is applied to the zirconia tube 1 by printing to a thickness of about 1 to 50 μm, and then the precious metal paste and the zirconia tube 1 are applied.
An electrode is formed on the surface of the zirconia tube 1 by simultaneously sintering at a high temperature of about 1100 to 1300 ° C. As a method of applying the noble metal paste to the zirconia tube 1, there are dipping, brush coating, spray injection and the like in addition to the above printing, but printing is particularly preferable.
【００１３】上記のようにして、白金Ｐｔ電極中にロジ
ウムＲｈとパラジウムＰｄとの少なくと一方が添加され
ると、図２に示すように、低温活性が向上し、ヒータ無
しでの低温作動化が可能となる。図２に明らかなよう
に、ロジウムＲｈ，パラジウムＰｄを添加しない白金Ｐ
ｔ電極を用いた場合に対し、ロジウムＲｈをより多く添
加することで低温活性が良くなるが、極端にロジウムＲ
ｈ単独で電極を形成させた場合には、低温活性の向上は
望めず、また、コスト的にもアップすることにので、前
述のように0.5 〜50wt％程度の割合で添加することが好
ましい。As described above, when at least one of rhodium Rh and palladium Pd is added to the platinum Pt electrode, the low temperature activity is improved and the low temperature operation without a heater is performed as shown in FIG. Is possible. As is clear from FIG. 2, platinum P without addition of rhodium Rh and palladium Pd
Compared with the case of using the t electrode, the addition of a larger amount of rhodium Rh improves the low temperature activity.
When the electrode is formed by h alone, improvement in low-temperature activity cannot be expected and the cost is also increased. Therefore, it is preferable to add it in a ratio of about 0.5 to 50 wt% as described above.
【００１４】また、ロジウムＲｈ，パラジウムＰｄを有
機化合物（レジネート材）として白金Ｐｔペーストに混
ぜると、ペースト中に対する分散性が高まるので、少な
い添加率でより大きな触媒活性効果が得られるので、ロ
ジウムＲｈ，パラジウムＰｄを粉の状態で添加するより
も、有機化合物として白金Ｐｔペーストに添加すること
が好ましい。When rhodium Rh and palladium Pd are mixed with platinum Pt paste as an organic compound (resinate material), dispersibility in the paste is enhanced, and a larger catalytic activity effect can be obtained with a small addition rate. Palladium Pd is preferably added as an organic compound to the platinum Pt paste rather than being added in the form of powder.
【００１５】更に、ロジウムＲｈ，パラジウムＰｄ以外
のルテニウムＲｕやイリジウムＩｒを添加させた場合に
は、たとえ有機化合物として添加させた場合であって
も、ロジウムＲｈ，パラジウムＰｄのような触媒活性の
効果は得られず、白金Ｐｔペーストに添加する金属とし
ては、上記のロジウムＲｈ，パラジウムＰｄが好まし
い。Furthermore, when ruthenium Ru or iridium Ir other than rhodium Rh and palladium Pd is added, even if added as an organic compound, the effect of catalytic activity such as rhodium Rh and palladium Pd is obtained. As a metal to be added to the platinum Pt paste, rhodium Rh and palladium Pd are preferable.
【００１６】上記のように電極の触媒活性が向上すれ
ば、ヒータ無しで低温作動化を実現できる酸素センサを
提供でき、また、ヒータを必要としないから、ヒータ電
圧のリークによる素子破壊の惧れもなくなる。また、上
記のようにして、触媒活性が改善され低温作動化が促進
されれば、内燃機関の排気中の酸素濃度を検出するため
に設けられる場合には、機関の始動直後から排気中の酸
素濃度を計測することができ、前記酸素濃度の情報に基
づく空燃比フィードバック制御を早期に行わせて、機関
始動時（冷機時）の排気性状を改善できるようになる。If the catalytic activity of the electrode is improved as described above, it is possible to provide an oxygen sensor that can be operated at a low temperature without a heater, and since a heater is not required, there is a risk of element breakdown due to leakage of the heater voltage. Also disappears. Further, as described above, if the catalytic activity is improved and the low temperature operation is promoted, when the oxygen concentration in the exhaust gas of the internal combustion engine is detected, the oxygen concentration in the exhaust gas is increased immediately after the engine is started. The concentration can be measured, and the air-fuel ratio feedback control based on the information on the oxygen concentration can be performed at an early stage to improve the exhaust property when the engine is started (when the engine is cold).
【００１７】[0017]
【発明の効果】以上説明したように本発明にかかる酸素
センサの製造方法によると、主成分の白金Ｐｔにロジウ
ムＲｈとパラジウムＰｄとの少なくとも一方を添加した
貴金属ペーストに、セラミックスを添加してなる電極材
ペーストを、仮焼き状態の基体に塗布した後、前記電極
材と基体とを同時焼結させるようにしたので、電極の耐
久性を確保しつつ、電極の触媒活性を向上させることが
でき、以て、酸素センサの低温特性が向上するという効
果がある。As described above, according to the method for manufacturing an oxygen sensor of the present invention, ceramics is added to a precious metal paste in which at least one of rhodium Rh and palladium Pd is added to platinum Pt as a main component. After the electrode material paste is applied to the base body in the calcined state, the electrode material and the base body are simultaneously sintered, so that it is possible to improve the catalytic activity of the electrode while ensuring the durability of the electrode. Thus, there is an effect that the low temperature characteristics of the oxygen sensor are improved.
【図１】酸素センサ構造例を示す断面図。FIG. 1 is a cross-sectional view showing an example of an oxygen sensor structure.
【図２】本発明にかかる酸素センサの低温活性の向上効
果を示す線図。FIG. 2 is a diagram showing the effect of improving the low temperature activity of the oxygen sensor according to the present invention.
１ ジルコニアチューブ ２，３ 電極 ４ 保護層 1 Zirconia tube 2,3 Electrode 4 Protective layer
Claims (1)
の内外表面に電極をそれぞれ形成し、基準気体に接触さ
せた一方表面の電極と、被検出気体に接触させた他方表
面の電極との間に酸素分圧比に応じた起電力を発生する
酸素センサの製造方法であって、 主成分の白金ＰｔにロジウムＲｈとパラジウムＰｄとの
少なくとも一方を添加した貴金属ペーストに、セラミッ
クスを添加してなる電極材ペーストを、仮焼き状態の前
記基体に塗布した後、前記電極材と基体とを同時焼結さ
せる酸素センサの製造方法。1. An electrode is formed on each of the inner and outer surfaces of a substrate made of an oxygen ion conductive solid electrolyte, and the electrode is on one surface in contact with a reference gas and the electrode on the other surface is in contact with a gas to be detected. A method of manufacturing an oxygen sensor for generating an electromotive force according to an oxygen partial pressure ratio, comprising: an electrode obtained by adding ceramics to a noble metal paste obtained by adding at least one of rhodium Rh and palladium Pd to platinum Pt as a main component. A method for manufacturing an oxygen sensor, comprising applying a material paste to the base body in a calcined state, and then simultaneously sintering the electrode material and the base body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP43A JPH06160333A (en) | 1992-11-18 | 1992-11-18 | Manufacture of oxygen sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP43A JPH06160333A (en) | 1992-11-18 | 1992-11-18 | Manufacture of oxygen sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06160333A true JPH06160333A (en) | 1994-06-07 |
Family
ID=17982146
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP43A Pending JPH06160333A (en) | 1992-11-18 | 1992-11-18 | Manufacture of oxygen sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06160333A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013257184A (en) * | 2012-06-11 | 2013-12-26 | Toyota Motor Corp | Method of manufacturing oxygen sensor |
-
1992
- 1992-11-18 JP JP43A patent/JPH06160333A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013257184A (en) * | 2012-06-11 | 2013-12-26 | Toyota Motor Corp | Method of manufacturing oxygen sensor |
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