JPH09264871A - Porous film formation for ceramic body - Google Patents
Porous film formation for ceramic bodyInfo
- Publication number
- JPH09264871A JPH09264871A JP8097492A JP9749296A JPH09264871A JP H09264871 A JPH09264871 A JP H09264871A JP 8097492 A JP8097492 A JP 8097492A JP 9749296 A JP9749296 A JP 9749296A JP H09264871 A JPH09264871 A JP H09264871A
- Authority
- JP
- Japan
- Prior art keywords
- platinum
- ceramic body
- porous film
- forming
- solution
- 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
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
- C04B41/51—Metallising, e.g. infiltration of sintered ceramic preforms with molten metal
- C04B41/5122—Pd or Pt
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00991—Uses not provided for elsewhere in C04B2111/00 for testing
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、酸素濃淡電池型の
自動車エンジン用酸素センサ等の各種センサにおける電
極の形成に使用し得る、多孔質膜の形成方法、特に密着
強度に優れた白金の多孔質膜を形成し、耐久性に優れた
酸素センサを作製することができるセラミック体の多孔
質膜形成方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a porous film which can be used for forming electrodes in various sensors such as an oxygen sensor for an automobile engine of an oxygen concentration battery type, and in particular, a platinum porous film excellent in adhesion strength. The present invention relates to a method for forming a porous film of a ceramic body capable of forming a porous film and manufacturing an oxygen sensor having excellent durability.
【０００２】[0002]
【従来の技術】自動車用酸素センサとして用いられる酸
素センサは、ジルコニア等の酸素イオン伝導性を有する
固体電解質を一端閉塞の筒状あるいは板状に成形した
後、焼成して形成されたセラミック体の対向する表面に
白金等の耐熱性を有する金属の多孔質膜を形成して作製
される（図３参照）。このように作製された酸素センサ
は、両電極側の気相の酸素分圧に差があり、固相内部の
成分組成比が気相の酸素分圧と平衡に達する時間が短い
ような高温に保持される時、固相内に酸素勾配に対応し
て化学ポテンシャルが発生し、それに相殺する静電ポテ
ンシャルがネルンスト式に従った濃淡電池起電力として
発生する。2. Description of the Related Art An oxygen sensor used as an automobile oxygen sensor is a ceramic body formed by forming a solid electrolyte having oxygen ion conductivity such as zirconia into a cylinder or plate with one end closed and then firing the solid electrolyte. It is manufactured by forming a porous film of heat-resistant metal such as platinum on the opposing surfaces (see FIG. 3). The oxygen sensor manufactured in this way has a difference in the oxygen partial pressure of the gas phase on both electrode sides, and at high temperatures such that the composition ratio of the components in the solid phase reaches equilibrium with the oxygen partial pressure of the gas phase for a short time. When held, a chemical potential is generated in the solid phase corresponding to the oxygen gradient, and an electrostatic potential that cancels it is generated as a concentration cell electromotive force according to the Nernst equation.
【０００３】即ち、上述の酸素センサは、その一面に形
成された多孔質膜に検出対象のガス（検出ガス）を接触
させ、他方の面に形成された多孔質膜に基準ガスを接触
させて、検出ガスと基準ガスとの間の酸素分圧の差によ
り両多孔質膜間に発生する起電力を検出して、検出ガス
中の酸素ガス濃度を測定することができる。That is, in the above oxygen sensor, the gas to be detected (detection gas) is brought into contact with the porous film formed on one surface thereof, and the reference gas is brought into contact with the porous film formed on the other surface thereof. The oxygen gas concentration in the detection gas can be measured by detecting the electromotive force generated between both porous membranes due to the difference in oxygen partial pressure between the detection gas and the reference gas.
【０００４】上述の型の酸素センサにおいては、ジルコ
ニア固体電解質等の酸素イオン伝導性固体電解質の酸素
イオン伝導性を利用するために、３００℃以上の高温環
境下で用いられるため、多孔質膜と固体電解質との熱膨
張率の差から多孔質膜に大きな応力が働く。また、前記
酸素センサは自動車の排気ガスの温度変化の影響を受け
るので、極めて激しい温度変化に晒されることとなり、
前記応力も激しく変動する。従って、前記酸素センサを
長時間の使用に晒すと、これら応力により多孔質膜が剥
離して、酸素センサの劣化ないし寿命の低下を引き起こ
すことがある。即ち、酸素イオン伝導性固体電解質を用
いた酸素センサの作製に際しては、温度サイクルに対し
て割れないセラミック体の作製と、反応活性が高く堅牢
で密着性に優れた多孔質膜の作製が極めて重要である。In the above-mentioned type of oxygen sensor, in order to utilize the oxygen ion conductivity of the oxygen ion conductive solid electrolyte such as the zirconia solid electrolyte, it is used in a high temperature environment of 300 ° C. or higher, so that it is considered as a porous film. A large stress acts on the porous membrane due to the difference in the coefficient of thermal expansion from the solid electrolyte. Further, since the oxygen sensor is affected by the temperature change of the exhaust gas of the automobile, it will be exposed to an extremely severe temperature change,
The stress also fluctuates drastically. Therefore, if the oxygen sensor is exposed to long-term use, the stress may cause the porous film to peel off, which may cause deterioration of the oxygen sensor or a reduction in its life. That is, when producing an oxygen sensor using an oxygen ion conductive solid electrolyte, it is extremely important to produce a ceramic body that does not crack under temperature cycles and a porous membrane that has high reaction activity and is robust and has excellent adhesion. Is.
【０００５】[0005]
【発明が解決しようとする課題】セラミック体に多孔質
膜を形成する方法として広く一般に用いられている方法
は、金属ペーストをセラミック体の表面に塗布した後、
該金属ペーストとセラミック体とを一体焼成し、多孔質
膜を形成する方法である。しかしながらこの方法は、セ
ラミック体と多孔質膜との密着性には優れているもの
の、白金ペースト中に含まれる種々の添加物の影響で電
極、即ち多孔質膜の反応活性が低いため、高感度で精度
の高さが要求される酸素センサとしては用いることがで
きない。A widely used method for forming a porous film on a ceramic body is to apply a metal paste to the surface of the ceramic body,
This is a method of integrally firing the metal paste and the ceramic body to form a porous film. However, although this method has excellent adhesion between the ceramic body and the porous film, it has high sensitivity because the reaction activity of the electrode, that is, the porous film is low due to the influence of various additives contained in the platinum paste. Therefore, it cannot be used as an oxygen sensor that requires high accuracy.
【０００６】他の多孔質膜の形成方法としては、無電解
メッキ法がある。この方法は、電気分解を利用せずに、
溶液中からセラミック体表面上に金属を析出させて多孔
質膜を形成する方法である。しかしながらこの方法は、
多孔質膜の反応活性は高いものの、セラミック体と多孔
質膜との密着性に劣り、酸素センサとして用いた時にお
いて、激しい温度変化に晒されると金属の多孔質膜が剥
離して、酸素センサの劣化ないし寿命の低下を引き起こ
すことがある。Another method for forming a porous film is an electroless plating method. This method does not utilize electrolysis,
It is a method of forming a porous film by depositing a metal on the surface of a ceramic body from a solution. However, this method
Although the reaction activity of the porous film is high, the adhesion between the ceramic body and the porous film is poor, and when used as an oxygen sensor, the metal porous film peels off when exposed to a drastic temperature change, and the oxygen sensor Deterioration or shortening of life may occur.
【０００７】これら酸素センサの劣化ないし寿命の低下
を防止するには金属の多孔質膜とセラミック体との間の
接着強度（密着性）を改善することが有効であり、特開
昭５４−１３７３９４に開示される、ブラスト処理によ
るセラミック体の表面粗度を所定の大きさにする方法が
ある。該開示によれば、成形体の表面をブラスト処理又
は機械加工により粗面化した後、１７００℃〜１９００
℃で焼結して、多孔質膜を形成することにより、多孔質
膜とセラミック体との密着性を改善する旨が示されてい
る。It is effective to improve the adhesive strength (adhesiveness) between the metal porous film and the ceramic body in order to prevent the deterioration or shortening of the life of these oxygen sensors, and JP-A-54-137394. There is a method disclosed in US Pat. According to the disclosure, after the surface of the molded body is roughened by blasting or machining, it is 1700 ° C to 1900 ° C.
It is shown that the adhesion between the porous film and the ceramic body is improved by sintering at 0 ° C. to form the porous film.
【０００８】しかしながら特開昭５４−１３７３９４の
開示による方法では、成形体自身に物理的衝撃を伴うブ
ラスト処理又は機械加工を施すので、セラミック体自体
にヒビ等の破損が発生し、セラミック体自体の強度が低
下してしまい、多孔質膜の剥離は起こり難くなるものの
セラミック体自体が劣化してしまうことがある。However, according to the method disclosed in Japanese Patent Laid-Open No. 54-137394, the molded body itself is subjected to blast treatment or mechanical processing accompanied by physical impact, so that damage such as cracks occurs in the ceramic body itself, and the ceramic body itself is damaged. Although the strength is reduced and the peeling of the porous film is less likely to occur, the ceramic body itself may be deteriorated.
【０００９】そこで上述の事情を鑑み、本発明は、セラ
ミック体との高い密着性を有することにより、高温下及
び激しい温度変化に対しても多孔質膜が剥離することの
ない、また酸素センサとして用いる場合に、多孔質膜が
電極としての反応活性に優れたセラミック体の多孔質膜
形成方法を開発し、これを提供することを基本的な目的
とする。In view of the above circumstances, the present invention has a high adhesiveness with a ceramic body so that the porous film will not be peeled off even under high temperature and severe temperature change, and as an oxygen sensor. The basic object of the present invention is to develop and provide a method for forming a porous film of a ceramic body in which the porous film has excellent reaction activity when used.
【００１０】[0010]
【課題を解決するための手段】本発明者らは上述の目的
に従い鋭意研究を進めた結果、セラミック体の表面に多
孔質膜を形成する方法において、（１）酸を含む白金溶
液を前記セラミック体の表面に接触させる工程と、
（２）還元剤を前記白金溶液に添加し前記セラミック体
の表面に島状の白金核を析出させる工程と、（３）前記
白金核が析出したセラミック体表面に白金錯塩を主成分
とするメッキ液を接触させて前記セラミック体の表面に
層状のメッキ膜を形成する工程と、（４）前記メッキ膜
の形成されたセラミック体を熱処理して白金の多孔質膜
を形成する工程と、からなることを特徴とするセラミッ
ク体の多孔質膜形成方法を開発し、本発明を完成させ
た。Means for Solving the Problems The inventors of the present invention have conducted extensive studies in accordance with the above-mentioned object, and as a result, in a method for forming a porous film on the surface of a ceramic body, (1) a platinum solution containing an acid was added to the ceramic. Contacting the surface of the body,
(2) Adding a reducing agent to the platinum solution to deposit island-shaped platinum nuclei on the surface of the ceramic body, and (3) Plating containing platinum complex salt as a main component on the surface of the ceramic body on which the platinum nuclei are deposited. And a step of forming a layered plating film on the surface of the ceramic body by bringing a liquid into contact therewith, and (4) heat treating the ceramic body on which the plating film is formed to form a platinum porous film. The present invention has been completed by developing a method for forming a porous film of a ceramic body characterized by the above.
【００１１】前記塩化白金酸溶液には０．０３規定度以
上の酸を含有することが好ましく、また、含有する酸と
しては塩酸を用いることが好ましい。更に前記セラミッ
ク体としてジルコニア固体電解質を用い、前記白金溶液
として塩化白金酸溶液を用いることが好ましい。更に、
セラミック体の一方の面に基準ガス側電極としての多孔
質膜を、他方の面に検出ガス側電極としての多孔質膜を
形成し、基準ガス側と検出ガス側との酸素濃度差により
酸素濃度を検出する酸素センサの電極を作製するのに用
いるには極めて好ましい方法である。The chloroplatinic acid solution preferably contains an acid having a normality of 0.03 or more, and hydrochloric acid is preferably used as the contained acid. Further, it is preferable to use a zirconia solid electrolyte as the ceramic body and a chloroplatinic acid solution as the platinum solution. Furthermore,
A porous film as the reference gas side electrode is formed on one surface of the ceramic body, and a porous film as the detection gas side electrode is formed on the other surface, and the oxygen concentration is determined by the oxygen concentration difference between the reference gas side and the detection gas side. It is a very preferable method to be used for producing electrodes of an oxygen sensor for detecting oxygen.
【００１２】即ち本発明によれば、酸を含む白金溶液を
セラミック体の表面に接触させた後、還元剤を前記白金
溶液に添加することにより、前記セラミック体の表面に
分布が粗である極めて大きい白金核を形成することがで
きるため、その後の無電解メッキ法、即ち白金核が析出
したセラミック体表面に白金錯塩を主成分とするメッキ
液を接触させて前記セラミック体の表面に層状のメッキ
膜を形成し、該メッキ膜の形成されたセラミック体を熱
処理することにより、セラミック体との密着性と、電極
としての反応活性に優れた多孔質膜を形成することがで
きる。That is, according to the present invention, a platinum solution containing an acid is brought into contact with the surface of the ceramic body, and then a reducing agent is added to the platinum solution so that the distribution on the surface of the ceramic body is very rough. Since a large platinum nucleus can be formed, a subsequent electroless plating method, that is, a plating solution containing a platinum complex salt as a main component is brought into contact with the surface of the ceramic body on which the platinum nucleus is deposited to form a layered plating on the surface of the ceramic body. By forming a film and heat-treating the ceramic body on which the plated film is formed, it is possible to form a porous film having excellent adhesion to the ceramic body and excellent reaction activity as an electrode.
【００１３】[0013]
【発明の実施の形態】本発明によれば、セラミック体の
表面に多孔質膜を形成する方法において、酸を含む白金
溶液を前記セラミック体の表面に接触させる工程（以
下、工程１と略す）と、還元剤を前記白金溶液に添加し
前記セラミック体の表面に島状の白金核を析出させる工
程（以下工程２と略す）と、前記白金核が析出したセラ
ミック体表面に白金錯塩を主成分とするメッキ液を接触
させて前記セラミック体の表面に層状のメッキ膜を形成
する工程（以下、工程３と略す）と、前記メッキ膜の形
成されたセラミック体を熱処理して白金の多孔質膜を形
成する工程（以下、工程４と略す）と、からなることを
特徴とするセラミック体の多孔質膜形成方法がある。BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, in a method for forming a porous film on a surface of a ceramic body, a step of bringing a platinum solution containing an acid into contact with the surface of the ceramic body (hereinafter abbreviated as step 1) And a step of adding a reducing agent to the platinum solution to deposit island-shaped platinum nuclei on the surface of the ceramic body (hereinafter abbreviated as step 2), and a platinum complex salt as a main component on the ceramic body surface on which the platinum nuclei are deposited. And a step of forming a layered plating film on the surface of the ceramic body by bringing the plating solution into contact therewith (hereinafter abbreviated as step 3), and heat treating the ceramic body on which the plating film is formed to form a platinum porous film. And a step (hereinafter, abbreviated as step 4) of forming a.
【００１４】本発明による工程１及び２によれば、例え
ば塩酸を含有する白金溶液を用いることにより、塩酸を
含有しない場合に比して、島状（核の分布が粗である状
態、図１に示す）でより大きな白金核を形成することが
できる。これは、塩酸の影響により白金核の形成速度が
遅くなったためと考えられる。なお、図１に塩酸を含有
しない白金溶液を用いた場合（ａ）と塩酸を含有する白
金溶液を用いた場合（ｂ）とにおいて、工程１及び工程
２を行った後の、白金核が形成されたセラミック体表面
のＸＭＡ元素分析結果（カラーマッピング）写真を示
す。塩酸を含有する白金溶液を用いた場合（ａ）は分布
が密であり（ｂ）に比して小さい白金核が析出している
のに対して、塩酸を含有する白金溶液を用いた場合
（ｂ）は、分布が粗であり、（ａ）に比して大きな白金
核が形成されていることがわかる。According to steps 1 and 2 of the present invention, by using, for example, a platinum solution containing hydrochloric acid, an island shape (rough distribution of nuclei, as shown in FIG. Larger platinum nuclei can be formed by It is considered that this is because the formation rate of platinum nuclei decreased due to the influence of hydrochloric acid. In FIG. 1, platinum nuclei are formed after performing steps 1 and 2 in the case of using a platinum solution containing no hydrochloric acid (a) and in the case of using a platinum solution containing hydrochloric acid (b). The XMA elemental analysis result (color mapping) photograph of the surface of the formed ceramic body is shown. When a platinum solution containing hydrochloric acid is used, the distribution is dense and platinum nuclei smaller than those in (b) are deposited, whereas when a platinum solution containing hydrochloric acid is used ( It can be seen that the distribution of b) is coarse and that larger platinum nuclei are formed as compared with (a).
【００１５】更に工程３及び４においては、前記白金核
を中心として白金が析出し、これが連続膜となり白金の
メッキ膜が形成される。この時の白金の析出による連続
膜の形成過程において、各々の白金核を中心として成長
した白金析出体は、その中心の白金核から離れる方向に
成長する。従って一つの白金核を中心として成長した一
つの白金析出体と、他の白金核を中心として成長した他
の白金析出体と、が連結するときにおいては、各々の白
金析出体の成長する方向が逆であるため、互いに押し合
う力が働き、この力が白金核の分布する密度に応じて積
み重なる結果、内部応力が蓄積される。この内部応力が
大きいと、セラミック体との密着性が悪くなる。白金核
の分布が密（白金核同士の距離が短い）である場合にお
いては前記連結の回数（白金析出体同士が連結する数）
が多くなる（白金核が密である）ため、内部応力も大き
くなるのに対し、本発明による工程１及び２において形
成された白金核は白金核の分布が粗であるため、前記連
結の回数が少なく、結果的に内部応力の小さい白金のメ
ッキ膜が形成され、セラミック体との密着性も高くなる
と考えられる。Further, in steps 3 and 4, platinum is deposited centering on the platinum nuclei, and this becomes a continuous film to form a platinum plating film. In the process of forming a continuous film by depositing platinum at this time, the platinum deposits grown around each platinum nucleus grow in a direction away from the central platinum nucleus. Therefore, when one platinum precipitate that has grown around one platinum nucleus and another platinum precipitate that grows around another platinum nucleus are connected, the growth direction of each platinum precipitate is Since they are opposite to each other, the forces of pushing each other work and the forces are piled up according to the distribution density of platinum nuclei, and as a result, internal stress is accumulated. When this internal stress is large, the adhesion with the ceramic body deteriorates. When the distribution of platinum nuclei is dense (the distance between platinum nuclei is short), the number of connections (the number of platinum precipitates connected)
Since the platinum nuclei are dense (the platinum nuclei are dense), the internal stress is also large, whereas the platinum nuclei formed in steps 1 and 2 according to the present invention have a coarse distribution of the platinum nuclei, so It is considered that a platinum plating film with less internal stress is formed, resulting in higher adhesion to the ceramic body.
【００１６】前記酸を含む白金溶液は、酸を０．０３規
定度以上含有することが好ましく、更に好ましくは０．
０６規定度以上であり、最も好ましくは０．１規定度以
上である。酸が塩酸である時は、前記白金溶液は特に塩
素を含有する白金化合物の溶液を用いることが好まし
く、例えば塩化白金酸（Ｈ2ＰｔＣｌ6）溶液を用いるこ
とができる。これは白金溶液が塩素を含有すると、次式
の平衡が左に傾き、白金溶液の分解が抑制されて安定化
し、白金の析出速度を遅くする作用があるため、分布が
粗である大きな白金核の形成を促進するからと考えられ
る。The platinum solution containing the acid preferably contains the acid in an amount of 0.03 normality or more, and more preferably 0.1.
It is at least 06 normality, most preferably at least 0.1 normality. When the acid is hydrochloric acid, it is particularly preferable to use a solution of a platinum compound containing chlorine as the platinum solution, for example, a chloroplatinic acid (H 2 PtCl 6 ) solution can be used. This is because when the platinum solution contains chlorine, the equilibrium of the following equation tilts to the left, the decomposition of the platinum solution is suppressed and stabilized, and it has the effect of slowing the platinum deposition rate. It is thought that this is because it promotes the formation of
【００１７】[0017]
【化１】 Embedded image
【００１８】また、酸を含む白金溶液は白金核の形成に
悪影響を与えない添加物であれば種々の添加物を含有す
ることができる。The acid-containing platinum solution may contain various additives as long as they do not adversely affect the formation of platinum nuclei.
【００１９】セラミック体としては、特に限定しない
が、自動車用酸素センサとして用いる場合は、酸素イオ
ン伝導性を有するセラミック体を用いることが好まし
く、例えば特開昭５４−４９１３号公報に記載のジルコ
ニア固体電解質等、高温下における使用にも耐え得る材
料を用いることができる。ジルコニア固体電解質を用い
る場合のジルコニア固体電解質の製法は、例えば、ジル
コニア（ＺｒＯ2）にイットリア（Ｙ2Ｏ3）を所定量添
加し、粉砕し、仮焼結を行った後、これを成形して所望
の形状とし、焼成することにより作製され得る。多孔質
膜を形成するためのセラミック体の形状は、筒状、平板
状、棒状、管状等、種々の形態をとることができ、特に
限定しないが、自動車用酸素センサとして用いる場合
は、一端閉塞の筒状とすることが好ましい（図３参
照）。図３は、酸素センサの一実施例の概略断面図を示
す。図３において、３１はセラミック体を、３２は基準
ガス側電極を、３３は検出ガス側電極を、３４は基準ガ
ス側、３５は検出ガス側を示す。The ceramic body is not particularly limited, but when used as an oxygen sensor for automobiles, it is preferable to use a ceramic body having oxygen ion conductivity, for example, a zirconia solid described in JP-A-54-4913. A material that can withstand use under high temperature such as an electrolyte can be used. When the zirconia solid electrolyte is used, the method for producing the zirconia solid electrolyte is, for example, adding a predetermined amount of yttria (Y 2 O 3 ) to zirconia (ZrO 2 ), crushing and calcination, and then molding this. It can be produced by firing into a desired shape by firing. The shape of the ceramic body for forming the porous film can take various forms such as a tubular shape, a flat plate shape, a rod shape, and a tubular shape, and is not particularly limited, but when used as an oxygen sensor for an automobile, one end is closed. It is preferable to have a cylindrical shape (see FIG. 3). FIG. 3 shows a schematic sectional view of one embodiment of the oxygen sensor. In FIG. 3, 31 is a ceramic body, 32 is a reference gas side electrode, 33 is a detection gas side electrode, 34 is a reference gas side, and 35 is a detection gas side.
【００２０】還元剤としては、白金溶液及びセラミック
体と不必要な反応を起こさない還元剤であれば、ヒドラ
ジン（Ｎ2Ｈ4）等種々の公知である還元剤を用いること
ができる。メッキ液としては、白金錯塩を主成分とする
メッキ液であれば種々の公知のメッキ液を用いることが
できる。As the reducing agent, various known reducing agents such as hydrazine (N 2 H 4 ) can be used as long as they do not cause unnecessary reaction with the platinum solution and the ceramic body. As the plating solution, various known plating solutions can be used as long as they are plating solutions containing a platinum complex salt as a main component.
【００２１】工程１において、酸を含む白金溶液を接触
させる部分は、セラミック体の表面であれば偏平面の
他、曲面、凹凸面等特に限定せず、多孔質膜を形成した
いセラミック体の表面に接触させればよい。特に、自動
車用酸素センサの電極の作製として用いる場合は、一端
閉塞の筒状セラミック体の内側の面と外側の面との２つ
の面に接触させるとよい。接触は、白金溶液がセラミッ
ク体に所定時間接触する状態に安置できる手段であれ
ば、塗布でもよいし、浸漬でもよいし、特に手段は限定
しない。酸の種類も特に塩酸が好ましいが、他の酸を用
いてもよい。In step 1, the part to be brought into contact with the platinum solution containing an acid is not particularly limited as long as it is the surface of the ceramic body such as a flat surface, a curved surface or an uneven surface, and the surface of the ceramic body on which a porous film is to be formed To contact. In particular, when it is used for producing an electrode of an oxygen sensor for an automobile, it is advisable to bring it into contact with two surfaces of an inner surface and an outer surface of a cylindrical ceramic body having one end closed. The contact may be coating or dipping as long as the platinum solution is kept in contact with the ceramic body for a predetermined time, and the means is not particularly limited. As the type of acid, hydrochloric acid is particularly preferable, but other acids may be used.
【００２２】工程２において、還元剤の添加は、該還元
剤を直接添加してもよいし、水、緩衝液等に希釈してか
ら添加してもよく、添加する手段は、塗布、浸漬等還元
剤が白金溶液を接触させたセラミック体部分に所定時間
接触する状態に安置できる手段であれば、特に手段は限
定しない。In step 2, the reducing agent may be added directly, or it may be added after diluting it with water, a buffer solution or the like. The means is not particularly limited as long as it can be placed in a state in which the reducing agent is in contact with the ceramic body portion in contact with the platinum solution for a predetermined time.
【００２３】工程３において、メッキ液を接触させる部
分は、工程１及び２において、酸を含む白金溶液を接触
させ、還元剤を添加した部分である。接触させる手段
は、工程１において塩酸を含む白金溶液を接触させる手
段と同様、メッキ液がセラミック体に所定時間接触する
状態に安置できる手段であれば、塗布でもよいし、浸漬
でもよいし、特に限定しない。In step 3, the portion to be brought into contact with the plating solution is the portion to which the platinum solution containing an acid was brought into contact and the reducing agent was added in steps 1 and 2. Similar to the means for contacting the platinum solution containing hydrochloric acid in step 1, the contacting means may be coating or dipping, as long as it can be placed in a state in which the plating solution is in contact with the ceramic body for a predetermined time, Not limited.
【００２４】工程４において、熱処理はメッキ膜から余
分な物質を除去した後に行うのが好ましく、例えば十分
に水洗いをした後、乾燥させた後に行うことが好まし
い。熱処理の雰囲気、温度、及び時間は、セラミック体
の大きさ、メッキ膜の大きさ、厚さ等により種々のもの
とすることができるが、温度は、好ましくは６００℃以
上１０００℃以下である。In step 4, the heat treatment is preferably performed after removing the extraneous substance from the plating film, for example, after thoroughly washing with water and drying. The atmosphere, temperature, and time for the heat treatment can be varied depending on the size of the ceramic body, the size of the plating film, the thickness, etc., but the temperature is preferably 600 ° C. or higher and 1000 ° C. or lower.
【００２５】また、本発明による多孔質膜の形成方法
は、自動車用酸素センサの電極を作製する際に用いるこ
とが好ましいが、他のセンサの電極形成用あるいはセン
サ以外のメッキ膜形成用等として用いることも可能であ
り、その用途は限定されない。Further, the method for forming a porous film according to the present invention is preferably used when producing an electrode of an oxygen sensor for automobiles, but for forming an electrode of another sensor or for forming a plating film other than the sensor. It can also be used and its use is not limited.
【００２６】[0026]
【実施例】以下、本発明の実施例について更に詳説す
る。但し、本発明はこれらの実施例に決して限定されな
い。Embodiments of the present invention will be described below in more detail. However, the invention is in no way limited to these examples.
【００２７】＜実施例１＞一端閉管構造のジルコニア固
体電解質（Ｙ2Ｏ3で安定化したＺｒＯ2９８％以上）の
内面をモル濃度５％のフッ酸にて処理した。水洗処理
後、０．１規定度の塩酸（ＨＣｌ）を加えた０．１ｇ／
ｌの塩化白金酸溶液（Ｈ2ＰｔＣｌ6）を該一端閉管構造
のジルコニア固体電解質の内面に塗布した後、還元剤と
してモル濃度５％のヒドラジン（Ｎ2Ｈ4）を添加して、
１時間安置してジルコニア固体電解質の表面に島状の白
金核を析出させた。更に該白金核が析出したジルコニア
固体電解質表面上に白金錯塩を主成分とするメッキ液に
接触させつつ所定の温度に加熱して無電解メッキ法によ
って層状の白金のメッキ膜を形成した。該メッキ膜が形
成されたジルコニア固体電解質を水洗いした後、乾燥し
た。次に該ジルコニア固体電解質を６００℃〜１０００
℃で熱処理を行い、白金の多孔質膜を有するジルコニア
固体電解質を得た。Example 1 The inner surface of a zirconia solid electrolyte (98% or more of ZrO 2 stabilized with Y 2 O 3 ) having a closed-end tube structure was treated with hydrofluoric acid having a molar concentration of 5%. After washing with water, 0.1g / 0.1g of hydrochloric acid (HCl) was added.
l of chloroplatinic acid solution (H 2 PtCl 6 ) was applied to the inner surface of the zirconia solid electrolyte having a closed-tube structure, and hydrazine (N 2 H 4 ) having a molar concentration of 5% was added as a reducing agent.
After standing for 1 hour, island-shaped platinum nuclei were deposited on the surface of the zirconia solid electrolyte. Further, a layered platinum plating film was formed on the surface of the zirconia solid electrolyte on which the platinum nuclei were deposited by contacting with a plating solution containing a platinum complex salt as a main component and heating to a predetermined temperature by an electroless plating method. The zirconia solid electrolyte on which the plated film was formed was washed with water and then dried. Next, the zirconia solid electrolyte is heated to 600 ° C. to 1000 ° C.
Heat treatment was performed at ℃, to obtain a zirconia solid electrolyte having a porous film of platinum.
【００２８】＜実施例２〜５及び比較例１＞塩化白金酸
溶液の塩酸含有量を異なる規定度とした他は実施例１と
同様の材料及び方法を用いてジルコニア固体電解質に多
孔質膜を形成し、塩化白金酸が含有する塩酸の規定度が
０Ｎ（塩酸無添加）のものを比較例１、塩酸の規定度が
０．０１５Ｎのものを実施例２、規定度が０．０３０Ｎ
のものを実施例３、規定度が０．０６０Ｎのものを実施
例４、規定度が０．１００Ｎのものを実施例５とし、実
施例一つにつき試料を５０個作製した。<Examples 2 to 5 and Comparative Example 1> A porous film was formed on the zirconia solid electrolyte by using the same materials and method as in Example 1 except that the hydrochloric acid content of the chloroplatinic acid solution was changed to different normality. The formed hydrochloric acid contained in the chloroplatinic acid has a normality of 0N (no addition of hydrochloric acid) in Comparative Example 1, and a hydrochloric acid has a normality of 0.015N in Example 2, and the normality is 0.030N.
The sample having the normality of 0.060 N was taken as Example 4, the sample having the normality of 0.100 N was taken as Example 5, and 50 samples were prepared for each example.
【００２９】＜密着性測定試験＞実施例２〜５及び比較
例１の多孔質膜が形成されたジルコニア固体電解質を水
素還元雰囲気中で７５０℃の高温に７時間晒し、フクレ
（blister；多孔質膜とジルコニア固体電解質との間に
ガス、液体等が蓄積して局部的にふくれる状態）が発生
したものの数により、フクレの発生率を算出し、塩酸濃
度の違いによる多孔質膜の密着性を調べた。この結果を
表１に示す。<Adhesion Measurement Test> The zirconia solid electrolytes having the porous membranes of Examples 2 to 5 and Comparative Example 1 were exposed to a high temperature of 750 ° C. for 7 hours in a hydrogen reducing atmosphere to generate blisters. The blister generation rate is calculated from the number of gas and liquid etc. that have accumulated locally between the membrane and the zirconia solid electrolyte, and the adhesiveness of the porous membrane due to the difference in hydrochloric acid concentration is calculated. Examined. Table 1 shows the results.
【００３０】[0030]
【表１】 [Table 1]
【００３１】更にこの結果をグラフにしたものを図２に
示す。図２は、横軸が塩化白金酸溶液に添加した塩酸の
規定度を、縦軸がフクレの発生率（％）を表す。塩酸を
含有しない塩化白金酸溶液を用いた比較例１において
は、フクレの発生率が８０％まで達しているのに対して
塩酸を含有する塩化白金酸溶液を用いた実施例２〜５に
おいては、塩化白金酸が含有する塩酸の濃度が増加する
につれてフクレの発生率が減少し、塩酸濃度０．０３規
定度（実施例２）では約６％に、塩酸濃度０．０６規定
度以上（実施例４〜５）においては、フクレの発生率は
ほぼ０％となった。即ち、セラミック体に対する多孔質
膜の密着性は、白金溶液が含有する塩酸の濃度に依存
し、該塩酸の濃度が高くなるほど密着性が高くなること
がわかる。従って、本発明による塩酸を含有する白金溶
液を用いれば、高い密着性の多孔質膜を有するセラミッ
ク体を作製することができる。Further, a graph of this result is shown in FIG. In FIG. 2, the horizontal axis represents the normality of hydrochloric acid added to the chloroplatinic acid solution, and the vertical axis represents the occurrence rate of blisters (%). In Comparative Example 1 using a chloroplatinic acid solution containing no hydrochloric acid, the occurrence rate of blisters reached 80%, whereas in Examples 2 to 5 using a chloroplatinic acid solution containing hydrochloric acid. The generation rate of blisters decreases as the concentration of hydrochloric acid contained in chloroplatinic acid increases, and becomes about 6% at a hydrochloric acid concentration of 0.03 normality (Example 2), and a hydrochloric acid concentration of 0.06 normality or higher (implemented). In Examples 4 to 5), the occurrence rate of blisters was almost 0%. That is, the adhesion of the porous film to the ceramic body depends on the concentration of hydrochloric acid contained in the platinum solution, and the higher the concentration of hydrochloric acid, the higher the adhesion. Therefore, by using the platinum solution containing hydrochloric acid according to the present invention, it is possible to produce a ceramic body having a porous film with high adhesion.
【００３２】＜実施例３＞図４に本発明による方法を用
いて作製した自動車用酸素センサの一実施例を示す。酸
素センサ４１は、ジルコニア固体電解質４２と、その内
面及び外面に本発明による方法により形成された白金の
多孔質膜の電極４３と、を具備する検出素子部４４によ
り酸素濃度が測定される。また、検出素子部４４は、管
状部材４５及び充填剤４６を介して、耐熱鋼製のハウジ
ング４７に固定され、更に検出素子部４４の先端には保
護管４８が被せられている。<Embodiment 3> FIG. 4 shows an embodiment of an automobile oxygen sensor manufactured by the method according to the present invention. The oxygen concentration of the oxygen sensor 41 is measured by a detection element unit 44 including a zirconia solid electrolyte 42 and a platinum porous film electrode 43 formed on the inner and outer surfaces thereof by the method according to the present invention. The detection element section 44 is fixed to a housing 47 made of heat-resistant steel via a tubular member 45 and a filler 46, and the tip of the detection element section 44 is covered with a protective tube 48.
【００３３】[0033]
【発明の効果】酸を含む白金溶液を用いてセラミック体
の表面を処理し、セラミック体の表面に分布が粗である
極めて大きい白金核を形成させた後、無電解メッキ法を
行うことにより、セラミック体との間の密着性に優れ、
電極としての反応活性に優れた多孔質膜を形成すること
ができる。The surface of the ceramic body is treated with a platinum solution containing an acid to form extremely large platinum nuclei having a coarse distribution on the surface of the ceramic body, and then the electroless plating method is performed. Excellent adhesion to the ceramic body,
It is possible to form a porous film having excellent reaction activity as an electrode.
【図１】（ａ）は塩酸を含有しない白金溶液を用いて析
出された白金核のＸＭＡ元素分析結果（カラーマッピン
グ）を表す金属組織の写真、（ｂ）は本発明による、塩
酸を含有する白金溶液を用いて析出された白金核のＸＭ
Ａ元素分析結果（カラーマッピング）を表す金属組織の
写真である。FIG. 1 (a) is a photograph of a metal structure showing an XMA elemental analysis result (color mapping) of a platinum nucleus deposited using a hydrochloric acid-free platinum solution, and FIG. 1 (b) contains hydrochloric acid according to the present invention. XM of platinum nuclei deposited using platinum solution
It is a photograph of a metal structure showing an A elemental analysis result (color mapping).
【図２】比較例１、及び本発明の実施例２〜５に関する
フクレの発生率を示すグラフである。FIG. 2 is a graph showing blistering rates for Comparative Example 1 and Examples 2-5 of the present invention.
【図３】酸素センサを示す概略断面図である。FIG. 3 is a schematic sectional view showing an oxygen sensor.
【図４】本発明による方法を用いて作製された自動車用
酸素センサの一実施例である。FIG. 4 is an example of an automotive oxygen sensor made using the method according to the present invention.
３１・・・セラミック体 ３２・・・基準ガス側電極 ３３・・・検出ガス側電極 ３４・・・基準ガス側 ３５・・・検出ガス側 ４１・・・酸素センサ ４２・・・ジルコニア固体電解質 ４３・・・電極 ４４・・・検出素子 ４５・・・管状部材 ４６・・・充填剤 ４７・・・ハウジング ４８・・・保護管 31 ... Ceramic body 32 ... Reference gas side electrode 33 ... Detection gas side electrode 34 ... Reference gas side 35 ... Detection gas side 41 ... Oxygen sensor 42 ... Zirconia solid electrolyte 43 ... Electrode 44 ... Detection element 45 ... Tubular member 46 ... Filler 47 ... Housing 48 ... Protective tube
Claims (5)
方法において、 （１）酸を含む白金溶液を前記セラミック体の表面に接
触させる工程と、 （２）還元剤を前記白金溶液に添加し前記セラミック体
の表面に島状の白金核を析出させる工程と、 （３）前記白金核が析出したセラミック体表面に白金錯
塩を主成分とするメッキ液を接触させて前記セラミック
体の表面に層状のメッキ膜を形成する工程と、 （４）前記メッキ膜の形成されたセラミック体を熱処理
して白金の多孔質膜を形成する工程と、 からなることを特徴とするセラミック体の多孔質膜形成
方法。1. A method for forming a porous film on a surface of a ceramic body, comprising: (1) contacting a platinum solution containing an acid with the surface of the ceramic body; and (2) adding a reducing agent to the platinum solution. Then, a step of depositing island-shaped platinum nuclei on the surface of the ceramic body, and (3) contacting a plating solution containing a platinum complex salt as a main component with the surface of the ceramic body on which the platinum nuclei are deposited on the surface of the ceramic body. A porous film of a ceramic body, comprising: a step of forming a layered plating film; and (4) a step of heat-treating the ceramic body on which the plating film is formed to form a platinum porous film. Forming method.
以上の酸を含むことを特徴とする請求項１に記載の多孔
質膜形成方法。2. The method for forming a porous film according to claim 1, wherein the platinum solution containing the acid contains an acid having a normality of 0.03 or more.
とを特徴とする請求項１又は２に記載の多孔質膜形成方
法。3. The method for forming a porous film according to claim 1, wherein the acid contained in the platinum solution is hydrochloric acid.
であり、前記白金溶液が塩化白金酸溶液であることを特
徴とする請求項１〜３のいずれか一に記載の多孔質膜形
成方法。4. The method for forming a porous film according to claim 1, wherein the ceramic body is a zirconia solid electrolyte, and the platinum solution is a chloroplatinic acid solution.
としての多孔質膜を、他方の面に検出ガス側電極として
の多孔質膜を、請求項１〜４のいずれか一に記載の方法
により形成し、基準ガス側と検出ガス側との酸素濃度差
により酸素濃度を検出する酸素センサを製造することを
特徴とする酸素センサの電極の製造方法。5. The porous film as the reference gas side electrode on one surface of the ceramic body, and the porous film as the detection gas side electrode on the other surface of claim 1. A method for manufacturing an electrode of an oxygen sensor, comprising: forming an oxygen sensor, which is formed by a method, and which detects an oxygen concentration based on a difference in oxygen concentration between a reference gas side and a detection gas side.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09749296A JP3594726B2 (en) | 1996-03-27 | 1996-03-27 | Method for forming porous film on ceramic body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09749296A JP3594726B2 (en) | 1996-03-27 | 1996-03-27 | Method for forming porous film on ceramic body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09264871A true JPH09264871A (en) | 1997-10-07 |
| JP3594726B2 JP3594726B2 (en) | 2004-12-02 |
Family
ID=14193777
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP09749296A Expired - Fee Related JP3594726B2 (en) | 1996-03-27 | 1996-03-27 | Method for forming porous film on ceramic body |
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| JP (1) | JP3594726B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11326267A (en) * | 1998-03-11 | 1999-11-26 | Ngk Spark Plug Co Ltd | Formation method for conductive film of ceramic body |
| JP2000121599A (en) * | 1998-08-12 | 2000-04-28 | Denso Corp | Gas sensor |
| GB2387230A (en) * | 2002-02-28 | 2003-10-08 | Ngk Spark Plug Co | Prismatic ceramic heater for heating a gas sensor |
| JP2007121323A (en) * | 2002-02-28 | 2007-05-17 | Ngk Spark Plug Co Ltd | Gas sensor |
| WO2013021549A1 (en) | 2011-08-10 | 2013-02-14 | Toyota Jidosha Kabushiki Kaisha | Method for manufacturing oxygen sensor |
-
1996
- 1996-03-27 JP JP09749296A patent/JP3594726B2/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11326267A (en) * | 1998-03-11 | 1999-11-26 | Ngk Spark Plug Co Ltd | Formation method for conductive film of ceramic body |
| JP2000121599A (en) * | 1998-08-12 | 2000-04-28 | Denso Corp | Gas sensor |
| GB2387230A (en) * | 2002-02-28 | 2003-10-08 | Ngk Spark Plug Co | Prismatic ceramic heater for heating a gas sensor |
| GB2387230B (en) * | 2002-02-28 | 2005-12-21 | Ngk Spark Plug Co | Prismatic ceramic heater for heating gas sensor element, prismatic gas sensor element in multi-layered structure including the prismatic ceramic heater, |
| JP2007121323A (en) * | 2002-02-28 | 2007-05-17 | Ngk Spark Plug Co Ltd | Gas sensor |
| US7329844B2 (en) | 2002-02-28 | 2008-02-12 | Ngk Spark Plug Co., Ltd. | Prismatic ceramic heater for heating gas sensor element, prismatic gas sensor element in multilayered structure including the prismatic ceramic heater, and method for manufacturing the prismatic ceramic heater and prismatic gas sensor element |
| WO2013021549A1 (en) | 2011-08-10 | 2013-02-14 | Toyota Jidosha Kabushiki Kaisha | Method for manufacturing 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 |
|---|---|
| JP3594726B2 (en) | 2004-12-02 |
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