JP2868920B2 - Element for measuring oxygen concentration in molten metal - Google Patents
Element for measuring oxygen concentration in molten metalInfo
- Publication number
- JP2868920B2 JP2868920B2 JP3080628A JP8062891A JP2868920B2 JP 2868920 B2 JP2868920 B2 JP 2868920B2 JP 3080628 A JP3080628 A JP 3080628A JP 8062891 A JP8062891 A JP 8062891A JP 2868920 B2 JP2868920 B2 JP 2868920B2
- Authority
- JP
- Japan
- Prior art keywords
- coating layer
- particle size
- molten metal
- powder
- oxygen concentration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Measuring Oxygen Concentration In Cells (AREA)
Description
【0001】[0001]
【産業上の利用分野】本発明は、溶融した金属の酸素濃
度を測定するために用いられる素子であって、固体電解
質体の外周面の溶融金属と接する面に被覆層を設けた構
造の酸素濃度測定用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 element used for measuring the oxygen concentration of a molten metal, wherein the element has a structure in which a coating layer is provided on the outer peripheral surface of a solid electrolyte body in contact with the molten metal. It relates to a concentration measuring element.
【0002】[0002]
【従来の技術】従来から、ジルコニア等の酸素イオン導
電性固体電解質を用いて片側が閉じた有底円筒形状と
し、その内側に金属ー金属酸化物を混合した固体極を封
入し、その外側に金属酸化物等による被覆層を付与した
構造のセンサ素子が知られている。上述した構造のセン
サ素子では、素子を溶融金属中に投入したとき被覆層が
高温の溶融金属中で焼結収縮し、剥離やクラックの発生
が生じ、溶融金属と固体電解質の接触面積が変化するた
め、安定した起電力波形が得られない問題があった。ま
た、被覆層の剥離やクラックの発生をなくすため、被覆
層の厚さを100μm 以上にすることも考えられるが、
そうすると応答時間が遅くなるという問題が生じてい
た。2. Description of the Related Art Conventionally, an oxygen ion conductive solid electrolyte such as zirconia has been used to form a closed-end cylindrical shape with one side closed, and a solid electrode mixed with a metal-metal oxide is sealed inside the inside, and outside the solid electrode. 2. Description of the Related Art A sensor element having a structure provided with a coating layer of a metal oxide or the like is known. In the sensor element having the above-described structure, when the element is put into the molten metal, the coating layer sinters and shrinks in the high-temperature molten metal, causing peeling and cracking, and changing the contact area between the molten metal and the solid electrolyte. Therefore, there is a problem that a stable electromotive force waveform cannot be obtained. It is also conceivable that the thickness of the coating layer is set to 100 μm or more in order to eliminate peeling and cracking of the coating layer.
Then, the problem that response time becomes slow occurred.
【0003】[0003]
【発明が解決しようとする課題】上述した被覆層の剥離
等の問題を解決するため、近年になって、高温でバイン
ダー効果のあるCaF2 を被覆層内に含ます技術が例え
ば特公昭61ー47377号公報において開示されている。しか
しながら、従来このバインダー効果を発揮させるために
はCaF2 を多量に添加しなければならず、CaF2 が
多量に添加されると被覆層の融点が下がり、その結果発
泡や溶けの発生により、溶融金属と固体電解質の接触面
積が変化し、安定した起電力波形を得ることができない
問題があった。In order to solve the above-mentioned problems such as peeling of the coating layer, a technique of including CaF 2 having a binder effect at a high temperature in the coating layer has recently been proposed, for example, in Japanese Patent Publication No. 61-1986. It is disclosed in Japanese Patent No. 47377. However, conventionally, in order to exert this binder effect, a large amount of CaF 2 must be added, and if a large amount of CaF 2 is added, the melting point of the coating layer decreases, and as a result, foaming and melting occur, and There is a problem that the contact area between the metal and the solid electrolyte changes, and a stable electromotive force waveform cannot be obtained.
【0004】本発明の目的は上述した課題を解消して、
弗化物のバインダー効果を利用できるとともに被覆層の
剥離やクラック発生のない溶融金属中の酸素濃度測定用
素子を提供しようとするものである。An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an element for measuring the oxygen concentration in a molten metal which can utilize the binder effect of fluoride and does not cause peeling or cracking of a coating layer.
【0005】[0005]
【課題を解決するための手段】本発明の溶融金属中の酸
素濃度測定素子は、固体電解質素子の外周面の溶融金属
と接する面に被覆層を設けた構造の酸素濃度測定用素子
において、前記被覆層を、弗化物を含有した酸化物の粉
末であって、平均粒子径:0.7〜1.4μmで粒度範
囲:0.1〜7μmの粉末10〜50重量%と、平均粒
子径:1.5〜2.5μmで粒度範囲:0.1〜15μ
mの粉末50〜90重量%とから構成したことを特徴と
するものである。According to the present invention, there is provided an element for measuring an oxygen concentration in a molten metal according to the present invention, which comprises a coating layer provided on a surface of the solid electrolyte element which is in contact with the molten metal on the outer peripheral surface. The coating layer is a powder of an oxide containing fluoride, which has an average particle diameter of 0.7 to 1.4 μm and a particle size range of 0.1 to 7 μm, and 10 to 50% by weight of the powder. 1.5 to 2.5 μm and particle size range: 0.1 to 15 μm
m of 50 to 90% by weight.
【0006】[0006]
【作用】上述した構成において、弗化物を含有する酸化
物であって2種類の粒度分布をもつ粉末を混合して被覆
層を形成することにより、大粒子の隙間を小粒子が埋め
ることにより粉末の充填密度をあげ緻密な被覆層を形成
することができるため、、焼結収縮を減少させることが
でき、その結果被覆層の剥離やクラックの発生を減少さ
せることができる。また、上述したように、被覆層の骨
材自体が緻密化し、クラックや剥離が減少するため、高
温中でバインダー効果のある弗化物の添加を小量に抑え
ることができ、被覆層の融点をあげることができ、その
結果被覆層の発泡や溶融を防止することができる。さら
に、被覆層の焼結収縮が減少するため、被覆層を薄く構
成することができ、溶融金属と固体電解質素子の内側に
設けた固体極の熱平衡に達する時間が速くなり、応答性
が向上する。In the above-described structure, a powder containing an oxide containing fluoride and having two kinds of particle size distributions is mixed to form a coating layer. Since the packing density can be increased and a dense coating layer can be formed, sintering shrinkage can be reduced, and as a result, peeling and cracking of the coating layer can be reduced. In addition, as described above, the aggregate itself of the coating layer is densified, and cracks and peeling are reduced, so that addition of fluoride having a binder effect at high temperatures can be suppressed to a small amount, and the melting point of the coating layer can be reduced. As a result, foaming and melting of the coating layer can be prevented. Furthermore, since the sintering shrinkage of the coating layer is reduced, the coating layer can be made thinner, and the time required to reach the thermal equilibrium between the molten metal and the solid electrode provided inside the solid electrolyte element is increased, and the responsiveness is improved. .
【0007】なお、2種類の粒度分布をもつ粉末として
は、後述する実施例から明らかなように、平均粒子径:
0.7〜1.4μm で粒度範囲:0.1〜7μm の粉末
10〜50重量%と、平均粒子径:1.5〜2.5μm
で粒度範囲:0.1〜15μm の粉末50〜90重量%
との混合物を使用すると、被覆層の緻密性があがり好ま
しい。[0007] The powder having two types of particle size distributions has an average particle diameter, as will be apparent from Examples described later.
10% to 50% by weight of a powder having a particle size range of 0.1 to 7 μm in a size of 0.7 to 1.4 μm, and an average particle size of 1.5 to 2.5 μm
Particle size range: 0.1 to 15 μm powder 50 to 90% by weight
The use of a mixture with the above is preferred because the density of the coating layer is increased.
【0008】[0008]
【実施例】図1は本発明の溶融金属中の酸素濃度測定用
素子の一例の構成を示す部分断面図である。図1におい
て、1は酸素イオン導電性を示すジルコニアからなる固
体電解質体、2は固体電解質体1の外周面の溶融金属と
接する面に設けた被覆層であり、有底円筒状の酸素濃度
測定用素子3を構成している。本発明では、この被覆層
2として2種類の粒度分布を有する弗化物を含有した酸
化物の粉末を混合したものを使用する必要がある。FIG. 1 is a partial sectional view showing the structure of an example of an element for measuring the concentration of oxygen in a molten metal according to the present invention. In FIG. 1, reference numeral 1 denotes a solid electrolyte body made of zirconia exhibiting oxygen ion conductivity, and 2 denotes a coating layer provided on the outer peripheral surface of the solid electrolyte body 1 in contact with the molten metal. Element 3 for use. In the present invention, it is necessary to use as the coating layer 2 a mixture of powders of oxides containing fluoride having two types of particle size distribution.
【0009】本発明において、ジルコニアからなる固体
電解質体1および酸素濃度測定用素子は以下のようにし
て製造される。まず、例えばジルコニア粉末92モル%
とマグネシア粉末8モル%と、その全量に対して1重量
%のアルミナ粉末を調合する。次に、得られた調合物を
水とジルコニア玉石により所定粒度となるまで粉砕す
る。粉砕後、バインダーとしてポリビニールアルコール
を加えた後、スプレードライヤにより造粒して、マグネ
シア部分安定化ジルコニア原料を得る。次に、得られた
原料を所定形状にラバープレス後、外周を切削して有底
円筒形状の成形体とした後、1700℃以上の温度で焼
成して、ジルコニアからなる固体電解質体1を得る。最
後に、有底円筒形状の固体電解質体1の外周面の溶融金
属と接する面に、弗化物を含有した酸化物の2種類の粒
度分布をもつ粉末を混合し、後述する方法でコーティン
グして被覆層2を形成することにより、本発明の溶融金
属中の酸素濃度測定用素子を得ている。In the present invention, the solid electrolyte member 1 made of zirconia and the element for measuring oxygen concentration are manufactured as follows. First, for example, 92 mol% of zirconia powder
And 8 mol% of magnesia powder and 1% by weight of alumina powder with respect to the total amount. Next, the obtained mixture is pulverized with water and zirconia cobblestone to a predetermined particle size. After pulverization, polyvinyl alcohol is added as a binder, and the mixture is granulated by a spray dryer to obtain a magnesia partially stabilized zirconia raw material. Next, after the obtained raw material is rubber-pressed into a predetermined shape, the outer periphery is cut into a cylindrical shape with a bottom, and then fired at a temperature of 1700 ° C. or more to obtain a solid electrolyte body 1 made of zirconia. . Finally, a powder having two kinds of particle size distributions of an oxide containing fluoride is mixed with the surface of the outer peripheral surface of the bottomed cylindrical solid electrolyte body 1 which is in contact with the molten metal, and coated by a method described later. By forming the coating layer 2, the element for measuring the oxygen concentration in the molten metal of the present invention is obtained.
【0010】次に、被覆層2について詳細に説明する。
被覆層2は、2種類の粒度分布をもつ弗化物が含有され
た酸化物と有機バインダーにより構成される。酸化物の
例としては、アルミナ、マグネシア、カルシア、ジルコ
ニアおよびアルミナとの複合酸化物であるアルミナマグ
ネシアスピネル、アルミナストロンチア等が使用でき
る。また、弗化物の例としては、弗化カルシウム、弗化
マグネシウム、弗化アルミニウム、弗化ストロンチウム
等が使用できる。その製造法は、まず上記酸化物の1種
類を80〜90重量%と上記弗化物の1種類を10〜2
0重量%とを調合する。次に、得られた調合粉末をトロ
ンメル中で水とジルコニア玉石を使用して粉砕する。異
なる粒度分布の粉末を得るため、粉砕時間を変えて粉砕
した後、得られた粉砕物を乾燥し、弗化物を含有した好
ましくは平均粒子径:0.7〜1.4μm で粒度範囲:
0.1〜7μm の酸化物粉末と、平均粒子径:1.5〜
2.5μm で粒度範囲:0.1〜15μm の酸化物粉末
とを得る。次に、上記粒度分布の異なる弗化物が含有し
た酸化物粉末2種類と水と有機バインダーとを混合し、
被覆液とする。この被覆液に固体電解質体の被覆層を設
ける面を浸漬後、乾燥して、本発明の被覆層2を固体電
解質体1の外周部に設けた酸素濃度測定用素子を得てい
る。Next, the coating layer 2 will be described in detail.
The coating layer 2 is composed of an oxide containing fluoride having two kinds of particle size distributions and an organic binder. Examples of the oxide include alumina, magnesia, calcia, zirconia, and a composite oxide of alumina, magnesia spinel, and alumina strontia. Examples of the fluoride include calcium fluoride, magnesium fluoride, aluminum fluoride, strontium fluoride and the like. First, one of the oxides is 80 to 90% by weight and one of the fluorides is 10 to 2%.
0% by weight. Next, the obtained prepared powder is ground in a trommel using water and zirconia cobblestone. In order to obtain powders having different particle size distributions, the resulting mixture is pulverized for different pulverization times, and the obtained pulverized product is dried, preferably containing fluoride and having an average particle size of 0.7 to 1.4 μm and a particle size range of:
0.1 to 7 μm oxide powder and average particle size: 1.5 to
An oxide powder having a particle size range of 0.1 to 15 μm at 2.5 μm is obtained. Next, two kinds of oxide powders containing fluorides having different particle size distributions, water and an organic binder were mixed,
Use as coating solution. After the surface on which the coating layer of the solid electrolyte body is provided is immersed in the coating liquid and dried, an element for measuring oxygen concentration in which the coating layer 2 of the present invention is provided on the outer peripheral portion of the solid electrolyte body 1 is obtained.
【0011】以下、実際の例について説明する。実施例1 表1に示すような平均粒子径および粒度分布を有する2
種類のスピネル粉末とスピネル粉末全量に対して15重
量%のCaF2 とからなる厚さ100μm 被覆層をジル
コニア固体電解質体の外周部に設けてなる酸素濃度測定
用素子を作製し、10kg高周波誘導炉中で1650℃
のFe−C−O系の溶鋼中に一定時間浸漬保持し、その
後引き上げて被覆層の状態を目視で観察した。なお、粒
度分布の測定はレーザ散乱法により行った。また、2種
類の粒度分布の粉末を混合した粒度分布の一例を図2に
示す。結果を表1に示す。Hereinafter, an actual example will be described. Example 1 2 having an average particle size and particle size distribution as shown in Table 1
A 10 kg high-frequency induction furnace was prepared by preparing an element for measuring oxygen concentration in which a 100 μm-thick coating layer composed of various kinds of spinel powder and 15 wt% CaF 2 with respect to the total amount of the spinel powder was provided on the outer periphery of the zirconia solid electrolyte body. 1650 ° C in
Was immersed and held in Fe-CO-based molten steel for a certain period of time, and then pulled up to visually observe the state of the coating layer. The particle size distribution was measured by a laser scattering method. FIG. 2 shows an example of a particle size distribution obtained by mixing powders having two types of particle size distributions. Table 1 shows the results.
【0012】[0012]
【表1】 [Table 1]
【0013】表1の結果から明らかなように、2種類の
粒度分布の粉末を使用した試験No2〜10は、いずれか
1種類しか使用しなかった試験No1、11と比べて不良
割合が少なく、その中でも2種類の粒度分布の粉末の添
加量が近い試験No6〜10はもっとも不良割合が少なか
った。As is clear from the results shown in Table 1, Test Nos. 2 to 10 using two kinds of powders having a different particle size distribution have a lower defective ratio than Test Nos. 1 and 11 using only one kind. Among them, Test Nos. 6 to 10 in which the amounts of the powders of the two kinds of particle size distributions were close to each other had the lowest defective rate.
【0014】実施例2 実施例1と同様に、表2に示すような平均粒子径および
粒度分布を有する2種類のスピネル粉末を原料として、
酸素濃度測定用素子を作製し、実施例1と同様に溶鋼浸
漬後の被覆層の状態を目視で観察した。結果を表2に示
す。 Example 2 As in Example 1, two types of spinel powders having an average particle size and a particle size distribution as shown in Table 2 were used as raw materials.
An element for measuring oxygen concentration was prepared, and the state of the coating layer after immersion in molten steel was visually observed in the same manner as in Example 1. Table 2 shows the results.
【0015】[0015]
【表2】 [Table 2]
【0016】表2の結果からも、2種類の粒度分布を有
する粉末を使用した試験No17〜24は、いずれか1種
類しか使用しなかった試験No12〜16と比べて不良割
合が少なかった。また、その中でも試験No18、19、
21、22が最良で、2種類の平均粒子径の範囲とし
て、平均粒子径が0.7〜1.4μm の粉末と平均粒子
径が1.5〜2.5μmの粉末を混合して使用すると好
ましいことがわかった。From the results shown in Table 2, the test Nos. 17 to 24 using the powders having two kinds of particle size distributions showed a lower percentage of defects than the test Nos. 12 to 16 using only one kind. Also, among them, Test No. 18, 19,
21 and 22 are the best, and as a range of two types of average particle diameters, a mixture of powder having an average particle diameter of 0.7 to 1.4 μm and powder having an average particle diameter of 1.5 to 2.5 μm is used. It turned out to be favorable.
【0017】実施例3 被覆層の厚さと応答性との関係を調べるため、実施例1
と同様に、表3に示すような平均粒子径を有する2種類
のスピネル粉末を原料として、酸素測定用素子を作製
し、実施例1と同様に被覆層の状態を目視で調べるとと
もに、浸漬後の起電力と応答時間を測定して応答性を比
較した。結果を表3に示す。 Example 3 In order to investigate the relationship between the thickness of the coating layer and the response, Example 1 was used.
In the same manner as in Example 1, two types of spinel powders having average particle diameters as shown in Table 3 were used as raw materials to prepare oxygen measurement elements, and the state of the coating layer was visually inspected in the same manner as in Example 1. The electromotive force and response time were measured and the response was compared. Table 3 shows the results.
【0018】[0018]
【表3】 [Table 3]
【0019】表3の結果から、2種類の平均粒子径の粉
末を使用した試験No29〜32は、いずれか1種類しか
使用しなかった試験No25〜28と比べて不良もなく、
応答時間が短くて応答性が良好であった。また、2種類
の平均粒子径の粉末を使用した場合は、試験No31に示
されるように、被覆層の厚さを50μm としても不良は
なく、また試験No32に示されるようにCaF2 の添加
量を低減しても不良がなく、厚さを薄くした分だけ応答
時間がさらに良くなることもわかった。From the results shown in Table 3, Test Nos. 29 to 32 using two kinds of powders having an average particle diameter had no defects compared with Test Nos. 25 to 28 using only one of the powders.
The response time was short and the response was good. When powders having two average particle diameters were used, there was no defect even when the thickness of the coating layer was 50 μm as shown in Test No. 31, and as shown in Test No. 32, the amount of CaF 2 added It was also found that there was no defect even if the thickness was reduced, and the response time was further improved by the reduction in thickness.
【0020】[0020]
【発明の効果】以上の説明から明らかなように、本発明
の溶融金属中の酸素濃度測定用素子によれば、弗化物を
含有する酸化物であって2種類の粒度分布をもつ粉末を
混合して被覆層を形成することにより、溶鋼浸漬時の被
覆層の剥離やクラック発生がなく、安定した起電力波形
を得ることができる。As is apparent from the above description, according to the element for measuring the oxygen concentration in the molten metal of the present invention, the oxide containing fluoride and the powder having two kinds of particle sizes are mixed. By forming the coating layer in this manner, a stable electromotive force waveform can be obtained without peeling or cracking of the coating layer during immersion in molten steel.
【図1】本発明の溶融金属中の酸素濃度測定用素子の一
例の構成を示す部分断面図である。FIG. 1 is a partial cross-sectional view showing a configuration of an example of an element for measuring an oxygen concentration in a molten metal according to the present invention.
【図2】本発明における2種類の粒度分布の粉末を混合
した粒度分布の一例を示すグラフである。FIG. 2 is a graph showing an example of a particle size distribution obtained by mixing powders having two types of particle size distribution in the present invention.
1 固体電解質体 2 被覆層 3 酸素濃度測定用素子 DESCRIPTION OF SYMBOLS 1 Solid electrolyte body 2 Coating layer 3 Element for measuring oxygen concentration
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6,DB名) G01N 27/411 ──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. 6 , DB name) G01N 27/411
Claims (1)
る面に被覆層を設けた構造の酸素濃度測定用素子におい
て、前記被覆層を、弗化物を含有した酸化物の粉末であ
って、平均粒子径:0.7〜1.4μmで粒度範囲:
0.1〜7μmの粉末10〜50重量%と、平均粒子
径:1.5〜2.5μmで粒度範囲:0.1〜15μm
の粉末50〜90重量%とから構成したことを特徴とす
る溶融金属中の酸素濃度測定用素子。1. An oxygen concentration measuring element having a structure in which a coating layer is provided on a surface of a solid electrolyte element that is in contact with a molten metal on an outer peripheral surface, wherein the coating layer is a powder of an oxide containing fluoride. Average particle size: 0.7 to 1.4 μm and particle size range:
10 to 50% by weight of a 0.1 to 7 μm powder, an average particle diameter of 1.5 to 2.5 μm and a particle size range of 0.1 to 15 μm
An element for measuring an oxygen concentration in a molten metal, comprising 50 to 90% by weight of a powder of
Priority Applications (1)
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JP3080628A JP2868920B2 (en) | 1991-03-20 | 1991-03-20 | Element for measuring oxygen concentration in molten metal |
Applications Claiming Priority (1)
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JP3080628A JP2868920B2 (en) | 1991-03-20 | 1991-03-20 | Element for measuring oxygen concentration in molten metal |
Publications (2)
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JPH04291146A JPH04291146A (en) | 1992-10-15 |
JP2868920B2 true JP2868920B2 (en) | 1999-03-10 |
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JP3080628A Expired - Lifetime JP2868920B2 (en) | 1991-03-20 | 1991-03-20 | Element for measuring oxygen concentration in molten metal |
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JP4961506B1 (en) * | 2011-11-30 | 2012-06-27 | 株式会社ニッカトー | Zirconia oxygen sensor element having a coating layer |
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1991
- 1991-03-20 JP JP3080628A patent/JP2868920B2/en not_active Expired - Lifetime
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JPH04291146A (en) | 1992-10-15 |
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