JPH1172460A - Oxygen sensor element and its manufacture - Google Patents
Oxygen sensor element and its manufactureInfo
- Publication number
- JPH1172460A JPH1172460A JP9235151A JP23515197A JPH1172460A JP H1172460 A JPH1172460 A JP H1172460A JP 9235151 A JP9235151 A JP 9235151A JP 23515197 A JP23515197 A JP 23515197A JP H1172460 A JPH1172460 A JP H1172460A
- Authority
- JP
- Japan
- Prior art keywords
- spinel
- protective layer
- sensor element
- oxygen sensor
- mgo
- 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.)
- Granted
Links
Landscapes
- Measuring Oxygen Concentration In Cells (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、各種燃料機器の酸
素濃度を検知するための酸素センサ素子、特に内燃機関
の排気ガスに含まれる酸素濃度を検出して、排気ガスを
浄化する空燃比制御等に用いることができる酸素センサ
素子及びその製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen sensor element for detecting the oxygen concentration of various fuel devices, and more particularly to an air-fuel ratio control for purifying the exhaust gas by detecting the oxygen concentration contained in the exhaust gas of an internal combustion engine. TECHNICAL FIELD The present invention relates to an oxygen sensor element that can be used for, for example, a method for manufacturing the same.
【０００２】[0002]
【従来の技術】従来より、排気ガス等の被測定ガスの酸
素濃度を検出する酸素センサ素子としては、例えば酸素
イオン伝導性をもつ部分安定化ジルコニア等の固体電解
質体を用いたものが知られている。2. Description of the Related Art Heretofore, as an oxygen sensor element for detecting the oxygen concentration of a gas to be measured such as exhaust gas, there has been known an oxygen sensor element using a solid electrolyte such as partially stabilized zirconia having oxygen ion conductivity. ing.
【０００３】この種の酸素センサ素子では、例えば有底
筒状の固体電解質体の表面において、その内面の基準大
気に晒される側に基準（貴金属）電極を備えるととも
に、その対面の被測定ガスに晒される側に測定（貴金
属）電極を備えており、更に、測定電極の表面は、測定
電極を被毒物質等から保護するために、スピネル等から
なる多孔質のセラミック保護層（スピネル保護層）で覆
われていた。In this type of oxygen sensor element, for example, a reference (precious metal) electrode is provided on the surface of a bottomed solid electrolyte body on the side exposed to the reference atmosphere, and a gas to be measured on the opposite side is provided. A measurement (noble metal) electrode is provided on the exposed side, and the surface of the measurement electrode is further covered with a porous ceramic protective layer (spinel protective layer) made of spinel or the like to protect the measurement electrode from poisoning substances. Was covered with.
【０００４】[0004]
【発明が解決しようとする課題】ところが、酸素センサ
素子は、高温で使用されるものであり、しかも固体電解
質や貴金属電極の活性を促すためのヒータ加熱による熱
衝撃が加わるので、スピネル保護層の密着性や耐久性が
低下して、ひいてはスピネル保護層の剥離の原因になる
ことがあった。However, since the oxygen sensor element is used at a high temperature, and is subjected to thermal shock due to heating of the heater to promote the activity of the solid electrolyte and the noble metal electrode, the oxygen sensor element has a problem in that the spinel protective layer is not used. Adhesion and durability may be reduced, which may cause peeling of the spinel protective layer.
【０００５】本発明は、前記課題を解決するためになさ
れたものであり、スピネル保護層の密着性や耐久性を向
上させ、その剥離を抑制することができる酸素センサ素
子及びその製造方法を提供することを目的とする。The present invention has been made to solve the above problems, and provides an oxygen sensor element capable of improving adhesion and durability of a spinel protective layer and suppressing peeling thereof, and a method of manufacturing the same. The purpose is to do.
【０００６】[0006]
【課題を解決するための手段】前記目的を達成するため
の請求項１の発明では、固体電解質体の一面側に大気に
晒される基準電極を設けるとともに、他面側に被測定ガ
スに晒される測定電極を備え、被測定ガスの酸素濃度を
検知する酸素センサ素子において、測定電極の上に、マ
グネシア・アルミナ・スピネル（ＭｇＡｌ2Ｏ4）からな
る多孔質のスピネル保護層を形成するとともに、該スピ
ネル保護層の組成を理論組成比よりＭｇＯリッチとする
ことを特徴とする酸素センサ素子を要旨とする。According to the first aspect of the present invention, there is provided a reference electrode which is exposed to the atmosphere on one side of a solid electrolyte body and is exposed to a gas to be measured on the other side. In an oxygen sensor element having a measurement electrode and detecting an oxygen concentration of a gas to be measured, a porous spinel protective layer made of magnesia-alumina-spinel (MgAl 2 O 4 ) is formed on the measurement electrode, and The gist of the present invention is an oxygen sensor element characterized in that the composition of the spinel protective layer is made more MgO-rich than the theoretical composition ratio.
【０００７】本発明では、スピネル保護層の組成を理論
組成比よりＭｇＯリッチとしている。つまり、図１に示
す様に、スピネルの機械的強度は、理論組成比（標準量
＝２８．３重量％）よりＭｇＯ含有量が大きいほど増加
する傾向があるので、ＭｇＯリッチとすることにより、
スピネル保護層の耐熱衝撃性を向上することができ、結
果として、スピネル保護層の密着性及び耐久性を向上さ
せて、その剥離を抑制することができる。尚、図１は、
J.T.Bailey and Ralston Russell JR,"Magnesia-Rich M
gAl2O4 Spinel Ceramics", Ceramics Bulletin,50 [5]
493-497 (1971)に掲載されているグラフである。In the present invention, the composition of the spinel protective layer is made MgO-rich from the theoretical composition ratio. That is, as shown in FIG. 1, the mechanical strength of the spinel tends to increase as the MgO content is larger than the stoichiometric composition ratio (standard amount = 28.3% by weight).
The thermal shock resistance of the spinel protective layer can be improved, and as a result, the adhesion and durability of the spinel protective layer can be improved, and peeling thereof can be suppressed. In addition, FIG.
JTBailey and Ralston Russell JR, "Magnesia-Rich M
gAl 2 O 4 Spinel Ceramics ", Ceramics Bulletin, 50 [5]
493-497 (1971).
【０００８】請求項２の発明は、スピネル保護層の組成
として、ＭｇＯを２８．５重量％以上とすることを特徴
とする請求項１に記載の酸素センサ素子を要旨とする。
後に詳述する様に、本発明者らによる冷熱耐久試験で
は、ＭｇＯ含有量が２８重量％以下では、冷熱サイクル
数が少ない場合でもスピネル保護層にクラックが入り易
いが、２９重量％以上では、冷熱サイクル数が多くなっ
てもクラックが入り難く、耐久性が高かった。従って、
ＭｇＯはその間の２８．５重量％以上では、境界値的に
高い耐久性が得られるものである。According to a second aspect of the present invention, there is provided an oxygen sensor element according to the first aspect, wherein the composition of the spinel protective layer is at least 28.5% by weight of MgO.
As described in detail later, in the thermal endurance test by the present inventors, when the MgO content is 28% by weight or less, the spinel protective layer is easily cracked even when the number of thermal cycles is small. Even when the number of cooling / heating cycles was large, cracks were hardly formed, and the durability was high. Therefore,
If MgO is 28.5% by weight or more, high durability can be obtained as a boundary value.
【０００９】尚、２９重量％では、実験により明確に高
い耐久性が得られることが分かるので、そのＭｇＯの組
成範囲のスピネル保護層を用いると、より確実な効果が
得られる。請求項３の発明は、スピネル保護層の組成と
して、ＭｇＯを３６重量％以下とすることを特徴とする
請求項１又は２に記載の酸素センサ素子を要旨とする。Experiments show that a high durability is clearly obtained at 29% by weight, so that a more reliable effect can be obtained by using a spinel protective layer having the MgO composition range. According to a third aspect of the present invention, there is provided an oxygen sensor element according to the first or second aspect, wherein the composition of the spinel protective layer is MgO of 36% by weight or less.
【００１０】一般にＭｇＯは吸水性があるので、スピネ
ル保護層の組成として、ＭｇＯが３６重量％を越える
と、その傾向が顕著になって、スピネル保護層の形状が
崩れ易くなる。従って、ＭｇＯは３６重量％以下で用い
ると、吸水性が過大となることなく、機械強度を増加さ
せることができる。尚、好ましくは３１重量％以下であ
る。In general, MgO has a water absorbing property. When the composition of the spinel protective layer exceeds 36% by weight, the tendency becomes remarkable, and the shape of the spinel protective layer is easily broken. Therefore, when MgO is used at 36% by weight or less, the mechanical strength can be increased without excessive water absorption. Incidentally, it is preferably at most 31% by weight.
【００１１】請求項４の発明は、固体電解質体は、主成
分がジルコニアであることを特徴とする請求項１〜３の
いずれかに記載の酸素センサ素子を要旨とする。ジルコ
ニアの熱膨張係数は、室温（Ｒ．Ｔ）→１０００℃で９
〜１１×１０-6／℃程度であるが、ＭｇＯの熱膨張係数
は、図２に示す様に、理論組成比からＭｇＯが増加する
ほど大きくなって、ジルコニアの熱膨張係数に近づく。
従って、このジルコニアを固体電解質として用いる場合
には、ＭｇＯ含有量を理論組成比より（実験では２８．
５重量％より）増加させることにより、固体電解質体と
スピネル保護層との熱膨張差を低減できる。よって、ス
ピネル保護層の熱による剥離や割れを防止することがで
きる。According to a fourth aspect of the present invention, there is provided an oxygen sensor element according to any one of the first to third aspects, wherein the main component of the solid electrolyte body is zirconia. The thermal expansion coefficient of zirconia is 9 at room temperature (RT) → 1000 ° C.
Although to 11 it is a × 10 -6 / ° C. approximately, the thermal expansion coefficient of MgO, as shown in FIG. 2, increases the stoichiometric composition ratio as MgO increases, approaching the thermal expansion coefficient of the zirconia.
Therefore, when this zirconia is used as a solid electrolyte, the MgO content is determined from the theoretical composition ratio (28.
By increasing the content (from 5% by weight), the difference in thermal expansion between the solid electrolyte body and the spinel protective layer can be reduced. Therefore, peeling or cracking of the spinel protective layer due to heat can be prevented.
【００１２】尚、ジルコニアとしては、ＺｒＯ2に例え
ばＹ2Ｏ3を５モル％程度添加した部分安定化ジルコニア
を採用することができる。尚、図２は、J.T.Bailey and
Ralston Russell JR,"Magnesia-Rich MgAl2O4 Spinel
Ceramics", Ceramics Bulletin,50 [5] 493-497 (1971)
に掲載されているグラフである。As the zirconia, partially stabilized zirconia obtained by adding, for example, about 5 mol% of Y 2 O 3 to ZrO 2 can be used. FIG. 2 shows JTBailey and
Ralston Russell JR, "Magnesia-Rich MgAl 2 O 4 Spinel
Ceramics ", Ceramics Bulletin, 50 [5] 493-497 (1971)
It is a graph published in.
【００１３】請求項５の発明は、請求項１〜４のいずれ
かに記載の酸素センサ素子の製造方法であって、スピネ
ル保護層をプラズマ溶射により形成することを特徴とす
る酸素センサ素子の製造方法を要旨とする。スピネル保
護層の原料粉末をプラズマ溶射することにより、所望の
箇所に容易にスピネル保護層を形成することができる。According to a fifth aspect of the present invention, there is provided a method of manufacturing an oxygen sensor element according to any one of the first to fourth aspects, wherein the spinel protective layer is formed by plasma spraying. The method is summarized. By subjecting the raw material powder for the spinel protective layer to plasma spraying, the spinel protective layer can be easily formed at a desired location.
【００１４】請求項６の発明は、スピネル保護層を形成
する材料として、マグネシア・アルミナ・スピネルの焼
結粉末を用いることを特徴とする請求項５に記載の酸素
センサ素子の製造方法を要旨とする。この焼結粉末と
は、原料粉末を一旦焼結したものを粉砕し、所定の粒径
に分級したものであり、多少コストは高くなるが、プラ
ズマ溶射の加熱の際に溶け易く、溶射性に優れている。According to a sixth aspect of the present invention, there is provided a method of manufacturing an oxygen sensor element according to the fifth aspect, wherein a sintered powder of magnesia-alumina-spinel is used as a material for forming the spinel protective layer. I do. This sintered powder is obtained by sintering the raw material powder once and then pulverizing it and classifying it into a predetermined particle size. The cost is somewhat high, but it is easily melted when heated by plasma spraying, and the Are better.
【００１５】請求項７の発明は、スピネル保護層を形成
する材料として、マグネシア・アルミナ・スピネルの電
融粉末を用いることを特徴とする請求項５に記載の酸素
センサ素子の製造方法を要旨とする。この電融粉末と
は、原料粉末を一旦電気的に加熱して溶かし、一旦反応
凝固させてから所定の粒径に粉砕分級したものであり、
プラズマ溶射の際の溶融性は多少低いが、コストが低い
という利点がある。According to a seventh aspect of the present invention, there is provided a method for manufacturing an oxygen sensor element according to the fifth aspect, wherein a fused powder of magnesia / alumina / spinel is used as a material for forming the spinel protective layer. I do. The electrofused powder is obtained by temporarily heating and melting the raw material powder, once solidifying by reaction, and then pulverizing and classifying to a predetermined particle size.
The meltability during plasma spraying is somewhat low, but has the advantage of low cost.
【００１６】[0016]
【発明の実施の形態】次に、本発明の酸素センサ素子及
びその製造方法を、例（実施例）を挙げて説明する。 ａ）まず、酸素センサ素子の構造を説明する。Next, an oxygen sensor element and a method of manufacturing the same according to the present invention will be described with reference to examples. a) First, the structure of the oxygen sensor element will be described.
【００１７】本実施例の酸素センサ素子は、例えば内燃
機関の空燃比制御を行なうために排気管に取り付けられ
る酸素センサ内に配置されて、被測定ガス（排気ガス）
中の酸素濃度を測定するものである。図３に示す様に、
この酸素センサ素子１は、部分安定化ジルコニアからな
る有底筒状の固体電解質体２を備え、その内周面には、
基準大気に晒されるＰｔからなる基準電極３が形成さ
れ、一方先端側の外周面には、被測定ガスに晒されるＰ
ｔからなる測定電極４が形成されている。The oxygen sensor element of the present embodiment is disposed in an oxygen sensor attached to an exhaust pipe for controlling an air-fuel ratio of an internal combustion engine, for example, and a gas to be measured (exhaust gas)
It measures oxygen concentration in the inside. As shown in FIG.
This oxygen sensor element 1 is provided with a bottomed cylindrical solid electrolyte body 2 made of partially stabilized zirconia,
A reference electrode 3 made of Pt exposed to a reference atmosphere is formed, while a Pt exposed to the gas to be measured is formed on the outer peripheral surface on the tip side.
A measurement electrode 4 made of t is formed.
【００１８】更に、この測定電極４の表面は、測定電極
４を被毒物質等から保護するために、マグネシア・アル
ミナ・スピネル（ＭｇＡｌ2Ｏ4スピネル）からなる多孔
質のセラミック保護層５で覆われている。このセラミッ
ク保護層５の組成は、理論組成比よりもＭｇＯリッチと
されている。具体的には、ＭｇＯは２８．５重量％以上
３６重量％以内の範囲内の例えば２９．５重量％とされ
ている。Further, the surface of the measuring electrode 4 is covered with a porous ceramic protective layer 5 made of magnesia alumina spinel (MgAl 2 O 4 spinel) in order to protect the measuring electrode 4 from poisoning substances and the like. Have been done. The composition of the ceramic protective layer 5 is made MgO richer than the theoretical composition ratio. Specifically, the content of MgO is, for example, 29.5% by weight within a range of 28.5% by weight or more and 36% by weight or less.
【００１９】ｂ）次に、本実施例の酸素センサ素子の製
造方法を説明する。 まず、ＺｒＯ2にＹ2Ｏ3を５ｍｏｌ％添加した部分安
定化ジルコニアの材料をスラリーとし、このスラリーを
スプレードライ方式にて乾燥造粒する。その粉末を、油
圧プレス法によって有底円筒形に形成し、所定の形状に
研削した後に、１５００℃にて焼成して固体電解質体２
を形成する。B) Next, a method for manufacturing the oxygen sensor element of the present embodiment will be described. First, a material of partially stabilized zirconia with Y 2 O 3 in ZrO 2 was added 5 mol% to form a slurry, dried granulate the slurry by a spray dry method. The powder is formed into a bottomed cylindrical shape by a hydraulic pressing method, ground into a predetermined shape, and then fired at 1500 ° C.
To form
【００２０】次に、固体電解質体２の内周面に、無電
解メッキ法により、Ｐｔからなる基準電極を形成すると
ともに、同様に、固体電解質体２の外周面の先端側に、
無電解メッキ法により、Ｐｔからなる測定電極４を形成
する。 次に、原料として、Ａｌ2Ｏ3：６９．５重量部、Ｍｇ
Ｏ：３０．５重量部を用意する。この場合、後の溶射に
よりＭｇＯが１重量％程度減少するので、目標とするＭ
ｇＯの組成比に応じて、ＭｇＯの成分を１重量％程度多
めのＭｇＯとする。Next, a reference electrode made of Pt is formed on the inner peripheral surface of the solid electrolyte body 2 by an electroless plating method.
The measurement electrode 4 made of Pt is formed by an electroless plating method. Then, as the raw material, Al 2 O 3: 69.5 parts by weight, Mg
O: Prepare 30.5 parts by weight. In this case, MgO is reduced by about 1% by weight by the subsequent thermal spraying.
According to the composition ratio of gO, the component of MgO is increased by about 1% by weight to MgO.
【００２１】そして、原料粉末として焼結粉末を用いる
場合には、Ａｌ2Ｏ3粉末とＭｇＯ粉末とを混合し、この
混合粉末を約１７００℃で焼成して、マグネシア・アル
ミナ・スピネルとし、この焼成体を数十μｍまで粉砕分
級して、粒径８０μｍ以下の原料粉末（ＭｇＡｌ2Ｏ4ス
ピネル粉末）とする。この焼結粉末は、焼成温度が低い
ため、溶射時に粉末が溶け易い。When a sintered powder is used as a raw material powder, an Al 2 O 3 powder and a MgO powder are mixed, and the mixed powder is fired at about 1700 ° C. to obtain magnesia-alumina spinel. The fired body is pulverized and classified to several tens of μm to obtain a raw material powder (MgAl 2 O 4 spinel powder) having a particle size of 80 μm or less. Since the sintering powder has a low sintering temperature, the powder is easily melted during thermal spraying.
【００２２】尚、焼結粉末以外に変えて、電融粉末を使
用できる。つまり、原料粉末として電融粉末を用いる場
合には、Ａｌ2Ｏ3とＭｇＯとを電気炉に入れて溶融し、
冷却凝固後のＭｇＡｌ2Ｏ4スピネルのインゴットを粉砕
し、分級して、粒径８０μｍ以下の原料粉末とする。It is to be noted that an electrofused powder can be used instead of the sintered powder. In other words, when using an electro-fused powder as the raw material powder, Al 2 O 3 and MgO are put into an electric furnace and melted,
The cooled and solidified MgAl 2 O 4 spinel ingot is pulverized and classified to obtain a raw material powder having a particle size of 80 μm or less.
【００２３】次に、図４に示す様に、プラズマガン６
を用いて下記の様にプラズマ溶射を行って、スピネル保
護層５を形成する。このプラズマガン６は、陰極である
中心電極と陽極となるノズルとの間に高電圧を印加し、
高周波点火装置によって発生させたアークで電極間に流
れている作動ガス（アルゴンガス）を励起し、プラズマ
状態とする。プラズマとなったガスは、著しい温度上昇
により体積膨張を起こし、ノズル出口６ａからフレーム
ガス流体（炎）となって噴出する。Next, as shown in FIG.
To form a spinel protective layer 5 by plasma spraying as described below. This plasma gun 6 applies a high voltage between a center electrode as a cathode and a nozzle as an anode,
The working gas (argon gas) flowing between the electrodes is excited by the arc generated by the high-frequency igniter to be in a plasma state. The gas that has become plasma undergoes volume expansion due to a remarkable temperature rise, and is emitted as a flame gas fluid (flame) from the nozzle outlet 6a.
【００２４】このとき、粉末供給装置７から一定流量の
ガスで供給されるスピネル粉末を、ノズル出口６ａにて
フレームに対して垂直方向から投入し、フレームの熱量
との勢いによって、粉末を溶解・加速させ、ターゲット
である測定電極４の表面等に連続的に衝突させる。At this time, spinel powder supplied from the powder supply device 7 with a constant flow rate of gas is supplied from the nozzle outlet 6a to the frame in a direction perpendicular to the frame, and the powder is melted and pressed by the heat of the frame. It is accelerated to continuously collide with the surface of the measurement electrode 4 as a target.
【００２５】つまり、プラズマのフレームを、（逆さま
に配置した）固体電解質体２の外周面の測定電極４に当
てて、プラズマガン６を上下させながら固体電解質体２
を回転させて、測定電極４の表面を覆う様に順次スピネ
ル保護層５を形成し、酸素センサ素子１を完成する。That is, the plasma frame is applied to the measurement electrode 4 on the outer peripheral surface of the solid electrolyte member 2 (disposed upside down), and the solid electrolyte member 2 is moved while the plasma gun 6 is moved up and down.
Is rotated to sequentially form the spinel protective layer 5 so as to cover the surface of the measurement electrode 4, thereby completing the oxygen sensor element 1.
【００２６】尚、このとき、他の箇所にプラズマのフレ
ームが当たらない様に、固体電解質体２の根元側は、キ
ャップ８により覆っておく。この様に、本実施例では、
ＭｇＡｌ2Ｏ4スピネルからなるスピネル保護層５の組成
として、ＭｇＯを理論組成比よりリッチの（例えば２
９．５重量％）としているので、スピネル保護層５の機
械的強度が高く、熱衝撃を受けた場合でも、密着性や耐
久性を高く保つことができ、結果として、スピネル保護
層５の剥離を防止することができる。At this time, the base of the solid electrolyte member 2 is covered with a cap 8 so that the plasma frame does not hit other portions. Thus, in this embodiment,
As a composition of the spinel protective layer 5 made of MgAl 2 O 4 spinel, MgO is richer than the theoretical composition ratio (for example, 2
9.5% by weight), the mechanical strength of the spinel protective layer 5 is high, and even when subjected to a thermal shock, the adhesion and durability can be kept high. As a result, the spinel protective layer 5 is peeled off. Can be prevented.
【００２７】しかも、前記ＭｇＯは３６重量％以下であ
るので、スピネル保護層５の吸水の程度が小さく、その
形状を良好に保つことができる。また、固体電解質体２
は、部分安定化ジルコニアから形成されているので、前
記スピネル保護層５と熱膨張差が少なく、その点からも
スピネル保護層５の剥離を防止できるという効果を奏す
る。Further, since the MgO content is 36% by weight or less, the degree of water absorption of the spinel protective layer 5 is small, and the shape thereof can be kept good. In addition, the solid electrolyte body 2
Is formed of partially stabilized zirconia, so that it has a small difference in thermal expansion from the spinel protective layer 5, and also has an effect that the peeling of the spinel protective layer 5 can be prevented.
【００２８】ｃ）次に、本発明の効果を確認した実験例
について説明する。 （実験例）次に、本発明の効果を確認するために行った
実験例について説明する。ここでは、前記のマグネシア
・アルミナ・スピネルの組成のうち、ＭｇＯ含有量を２
６〜３６重量％の間で１重量％づつ変化させた酸素セン
サ素子の試料を、各３個作製し、それらの試料に対し
て、加熱冷却試験（冷熱耐久試験）を行った。C) Next, an experimental example in which the effect of the present invention has been confirmed will be described. (Experimental Example) Next, an experimental example performed to confirm the effect of the present invention will be described. Here, the MgO content of the magnesia-alumina-spinel composition was 2
Three samples of the oxygen sensor element, each of which was changed by 1% by weight from 6 to 36% by weight, were prepared, and the samples were subjected to a heating / cooling test (cooling / heat resistance test).
【００２９】尚、各原料粉末のＭｇＯの含有量は、実際
のスピネル保護層におけるＭｇＯの含有量が２６〜３６
重量％間で１重量％つづとなる様に、予めその量を調節
した。この時、スピネル保護層において目的とするＭｇ
Ｏの成分量とする様に、原料粉末中におけるＭｇＯの量
を１重量％だけ多くした。Incidentally, the MgO content of each raw material powder is determined by the fact that the MgO content in the actual spinel protective layer is 26 to 36.
The amount was adjusted in advance so that the weight percentage was 1% by weight. At this time, the desired Mg in the spinel protective layer is
The amount of MgO in the raw material powder was increased by 1% by weight so that the amount of O was adjusted.
【００３０】具体的には、各試料の素子表面温度が、２
分間で５０℃から１１００℃まで上昇し再度５０℃に戻
る変化（従って２分間で１サイクル）を繰り返す加熱冷
却試験を行ない、スピネル保護層に何サイクルでクラッ
クが発生するかを調べた。その結果を、図５に示す。Specifically, the element surface temperature of each sample is 2
A heating / cooling test was repeated in which the temperature rose from 50 ° C. to 1100 ° C. in one minute and returned to 50 ° C. again (thus, one cycle in two minutes). The result is shown in FIG.
【００３１】図５から明かな様に、本発明の範囲のＭｇ
Ｏ含有量が２９重量％以上では、３００サイクル以上で
しかスピネル保護層にクラックが入らず、熱衝撃に対す
る耐久性が高く好適である。それに対して、本発明の範
囲外のＭｇＯ含有量が２８重量％以下では、２００サイ
クルにてスピネル保護層にクラックが入るので、熱衝撃
に対する耐久性が低く好ましくない。As is clear from FIG. 5, Mg within the scope of the present invention
When the O content is 29% by weight or more, cracks do not occur in the spinel protective layer only after 300 cycles or more, and the durability against thermal shock is high, which is preferable. On the other hand, when the MgO content outside the range of the present invention is 28% by weight or less, cracks occur in the spinel protective layer in 200 cycles, so that the durability against thermal shock is low, which is not preferable.
【００３２】なお、本発明は前記実施例になんら限定さ
れるものではなく、本発明の要旨を逸脱しない範囲にお
いて種々の態様で実施しうることはいうまでもない。It should be noted that the present invention is not limited to the above-described embodiment at all, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.
【００３３】[0033]
【発明の効果】以上詳述した様に、請求項１の発明で
は、スピネル保護層の組成を理論組成比よりＭｇＯリッ
チとしているので、スピネル保護層の耐熱衝撃性が向上
する。よって、スピネル保護層の密着性及び耐久性が向
上するので、その剥離を抑制することができる。As described above in detail, in the first aspect of the present invention, the composition of the spinel protective layer is made MgO-rich from the theoretical composition ratio, so that the thermal shock resistance of the spinel protective layer is improved. As a result, the adhesion and durability of the spinel protective layer are improved, and the peeling can be suppressed.
【００３４】請求項２の発明では、ＭｇＯは２８．５重
量％以上であるので、多くの冷熱サイクルでも、スピネ
ル層にクラックが入り難く、耐久性に優れている。請求
項３の発明では、ＭｇＯは３６重量％以下であるので、
吸水性が過大となることなく、機械強度を高く維持でき
る。According to the second aspect of the present invention, since MgO is 28.5% by weight or more, the spinel layer is less likely to crack even in many cooling and heating cycles, and is excellent in durability. According to the third aspect of the invention, since MgO is 36% by weight or less,
Mechanical strength can be maintained high without excessive water absorption.
【００３５】請求項４の発明では、固体電解質体のジル
コニアと、ＭｇＯリッチの場合のスピネル保護層との熱
膨差が小さいので、スピネル保護層の熱による剥離や割
れを防止することができる。請求項５の発明では、スピ
ネル保護層をプラズマ溶射により容易に形成することが
できる。According to the fourth aspect of the present invention, since the difference in thermal expansion between zirconia of the solid electrolyte body and the spinel protective layer in the case of being rich in MgO is small, peeling and cracking of the spinel protective layer due to heat can be prevented. According to the invention of claim 5, the spinel protective layer can be easily formed by plasma spraying.
【００３６】請求項６の発明では、マグネシア・アルミ
ナ・スピネルの焼結粉末を用いるので、プラズマ溶射の
際に粉末が溶け易く、溶射性に優れている。請求項７の
発明では、マグネシア・アルミナ・スピネルの電融粉末
を用いるので、コストを低減できる。According to the sixth aspect of the present invention, since the sintered powder of magnesia / alumina / spinel is used, the powder is easily melted by plasma spraying and has excellent spraying properties. According to the invention of claim 7, since the fused powder of magnesia / alumina / spinel is used, the cost can be reduced.
【図１】 ＭｇＯの含有量と破壊係数との関係を示すグ
ラフである。FIG. 1 is a graph showing the relationship between the content of MgO and the fracture coefficient.
【図２】 ＭｇＯの含有量と熱膨張係数との関係を示す
グラフである。FIG. 2 is a graph showing the relationship between the content of MgO and the coefficient of thermal expansion.
【図３】 酸素センサ素子の断面図である。FIG. 3 is a sectional view of an oxygen sensor element.
【図４】 プラズマ溶射によるスピネル保護層の形成方
法を示す説明図である。FIG. 4 is an explanatory view showing a method for forming a spinel protective layer by plasma spraying.
【図５】 冷熱耐久試験の結果を示すグラフである。FIG. 5 is a graph showing the results of a thermal endurance test.
１…酸素センサ素子 ２…固体電解質体 ３…基準電極 ４…測定電極 ５…スピネル保護層 DESCRIPTION OF SYMBOLS 1 ... Oxygen sensor element 2 ... Solid electrolyte body 3 ... Reference electrode 4 ... Measuring electrode 5 ... Spinel protective layer
Claims (7)
基準電極を設けるとともに、他面側に被測定ガスに晒さ
れる測定電極を備え、該被測定ガスの酸素濃度を検知す
る酸素センサ素子において、 前記測定電極の上に、マグネシア・アルミナ・スピネル
からなる多孔質のスピネル保護層を形成するとともに、
該スピネル保護層の組成を理論組成比よりＭｇＯリッチ
とすることを特徴とする酸素センサ素子。An oxygen sensor element having a reference electrode exposed to the atmosphere on one surface of a solid electrolyte body and a measurement electrode exposed to a gas to be measured on the other surface, and detecting an oxygen concentration of the gas to be measured. In the above, while forming a porous spinel protective layer made of magnesia alumina spinel on the measurement electrode,
An oxygen sensor element characterized in that the composition of the spinel protective layer is made MgO-rich from the theoretical composition ratio.
Ｏを２８．５重量％以上とすることを特徴とする前記請
求項１に記載の酸素センサ素子。2. The composition of the spinel protective layer is Mg
The oxygen sensor element according to claim 1, wherein O is 28.5% by weight or more.
Ｏを３６重量％以下とすることを特徴とする前記請求項
１又は２に記載の酸素センサ素子。3. The composition of the spinel protective layer is Mg
3. The oxygen sensor element according to claim 1, wherein O is 36% by weight or less.
アであることを特徴とする前記請求項１〜３のいずれか
に記載の酸素センサ素子。4. The oxygen sensor element according to claim 1, wherein a main component of the solid electrolyte body is zirconia.
素センサ素子の製造方法であって、 前記スピネル保護層をプラズマ溶射により形成すること
を特徴とする酸素センサ素子の製造方法。5. The method for manufacturing an oxygen sensor element according to claim 1, wherein said spinel protective layer is formed by plasma spraying.
て、マグネシア・アルミナ・スピネルの焼結粉末を用い
ることを特徴とする前記請求項５に記載の酸素センサ素
子の製造方法。6. The method according to claim 5, wherein a sintered powder of magnesia-alumina-spinel is used as a material for forming the spinel protective layer.
て、マグネシア・アルミナ・スピネルの電融粉末を用い
ることを特徴とする前記請求項５に記載の酸素センサ素
子の製造方法。7. The method for manufacturing an oxygen sensor element according to claim 5, wherein a fused powder of magnesia / alumina / spinel is used as a material for forming the spinel protective layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23515197A JP3655441B2 (en) | 1997-08-29 | 1997-08-29 | Oxygen sensor element and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23515197A JP3655441B2 (en) | 1997-08-29 | 1997-08-29 | Oxygen sensor element and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1172460A true JPH1172460A (en) | 1999-03-16 |
| JP3655441B2 JP3655441B2 (en) | 2005-06-02 |
Family
ID=16981814
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23515197A Expired - Fee Related JP3655441B2 (en) | 1997-08-29 | 1997-08-29 | Oxygen sensor element and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3655441B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1109013A2 (en) * | 1999-12-17 | 2001-06-20 | Ngk Spark Plug Co., Ltd | Gas sensor |
| JP2013036940A (en) * | 2011-08-10 | 2013-02-21 | Denso Corp | Method for manufacturing gas sensor element |
| US8834693B2 (en) | 2008-12-25 | 2014-09-16 | Denso Corporation | Gas sensor element and gas sensor including the same |
| DE102014112844A1 (en) | 2013-09-05 | 2015-03-05 | Ngk Spark Plug Co., Ltd. | Gas sensor element and gas sensor |
-
1997
- 1997-08-29 JP JP23515197A patent/JP3655441B2/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1109013A2 (en) * | 1999-12-17 | 2001-06-20 | Ngk Spark Plug Co., Ltd | Gas sensor |
| EP1109013A3 (en) * | 1999-12-17 | 2004-10-20 | Ngk Spark Plug Co., Ltd | Gas sensor |
| US8834693B2 (en) | 2008-12-25 | 2014-09-16 | Denso Corporation | Gas sensor element and gas sensor including the same |
| JP2013036940A (en) * | 2011-08-10 | 2013-02-21 | Denso Corp | Method for manufacturing gas sensor element |
| DE102014112844A1 (en) | 2013-09-05 | 2015-03-05 | Ngk Spark Plug Co., Ltd. | Gas sensor element and gas sensor |
| US10161900B2 (en) | 2013-09-05 | 2018-12-25 | Ngk Spark Plug Co., Ltd. | Gas sensor element and gas sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3655441B2 (en) | 2005-06-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3978006A (en) | Methods for producing oxygen-sensing element, particularly for use with internal combustion engine exhaust emission analysis | |
| CN100416267C (en) | Prismatic ceramic heater, prismatic gas sensitive element and its producing method | |
| US4219359A (en) | Sintered body of zirconia for oxygen concentration sensor | |
| JPS6147376B2 (en) | ||
| JPS6245496B2 (en) | ||
| JPH01184457A (en) | Oxygen sensor element | |
| EP2703350A1 (en) | Spinel powder and manufacturing process therefor, and processes for producing thermal spraying film and gas sensor elements | |
| JP2001174434A (en) | Gas sensor | |
| JPH1172460A (en) | Oxygen sensor element and its manufacture | |
| CN111315708B (en) | Solid electrolyte, method for producing same, and gas sensor | |
| JPS6338663B2 (en) | ||
| KR100327079B1 (en) | Electrochemical sensor with sensor element | |
| JP4271458B2 (en) | Spark plug | |
| JP2957542B1 (en) | Gas sensor element and manufacturing method thereof | |
| JP7052747B2 (en) | Exhaust sensor | |
| US11656196B2 (en) | Solid electrolyte, manufacturing method thereof, and gas sensor | |
| JPS63167261A (en) | Production of oxygen sensor element | |
| JPH11240755A (en) | Production of oxygen sensor element | |
| JP2001041922A (en) | Oxygen sensor element integrated with heater | |
| JP4700214B2 (en) | Oxygen sensor element and manufacturing method thereof | |
| JPH0510918A (en) | Oxygen-concentration detecting element and manufacture thereof | |
| JP4698041B2 (en) | Air-fuel ratio sensor element | |
| US12111282B2 (en) | Solid electrolyte and gas sensor with thermal shock resistance | |
| JP4744043B2 (en) | Air-fuel ratio sensor element | |
| JP4540222B2 (en) | Oxygen sensor and manufacturing method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20040513 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20040601 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20040730 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20050208 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20050303 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090311 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090311 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100311 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100311 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110311 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110311 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120311 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120311 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120311 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130311 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130311 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130311 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140311 Year of fee payment: 9 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |