JPS5928861B2 - gas detection element - Google Patents
gas detection elementInfo
- Publication number
- JPS5928861B2 JPS5928861B2 JP841779A JP841779A JPS5928861B2 JP S5928861 B2 JPS5928861 B2 JP S5928861B2 JP 841779 A JP841779 A JP 841779A JP 841779 A JP841779 A JP 841779A JP S5928861 B2 JPS5928861 B2 JP S5928861B2
- Authority
- JP
- Japan
- Prior art keywords
- gas
- detection element
- gas detection
- fe2o3
- mol
- 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
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- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Description
【発明の詳細な説明】 この発明はガス検知素子に関するものである。[Detailed description of the invention] The present invention relates to a gas detection element.
従来からガス検知素子として、sno2またはZnOを
主成分としたもの、およびこれらとPt、Pb等の貴金
属触媒を併用したもの等が知られている。ところが、上
記のガス検知素子のうち、sno2またはこれと貴金属
触媒とを併用したものは、素子製造の際の焼結が困難で
、苛酷な焼結により素子性能が低下しがちであり、周囲
湿度の影響も受けやすいという欠点があつた。また、Z
nOまたはこれと貴金属触媒とを併用したものは、高温
使用においてのみ始めて所望のガス感度を発揮するとい
う欠点があつた。また、sno2とZnOとを併用した
ものも用いられているが、このものは、素子製造の際に
、ZnOによりsno2の焼結が促進されるため、苛酷
な焼結による素子性能の低下はないものの周囲湿度の影
響を受けやすいという欠点があつた。この発明者らは、
このような事情に鑑み研究を重ねた結果、γ−Fe2O
3を用いると周囲湿度の影響を殆んど受けないガス検知
素子が得られることを見いだした。BACKGROUND ART Conventionally, gas detection elements have been known that have sno2 or ZnO as a main component, and those that use these together with a noble metal catalyst such as Pt or Pb. However, among the above gas sensing elements, sno2 or those using sno2 in combination with a noble metal catalyst are difficult to sinter during element manufacture, and the element performance tends to deteriorate due to severe sintering. The disadvantage was that it was easily influenced by Also, Z
The drawback of using nO or a combination thereof with a noble metal catalyst is that it exhibits the desired gas sensitivity only when used at high temperatures. Also, a combination of sno2 and ZnO is used, but in this case, the sintering of sno2 is promoted by ZnO during device manufacturing, so there is no deterioration in device performance due to severe sintering. The drawback was that it was easily affected by the ambient humidity. The inventors
As a result of repeated research in view of these circumstances, γ-Fe2O
It has been found that by using No. 3, a gas sensing element that is almost unaffected by ambient humidity can be obtained.
そして、この発明者らは、ガス検知素子のガス感応性を
示すものとして後述のようにして求められるガス感度、
濃度分離性、湿度依存性(周囲湿度による影響の受けや
すさを示す)にそれぞれ目標値を設定し(ガス感度:6
5%以上、濃度分離性: 1.70以上、湿度依存性=
1.1±0.2)この目標値を満足させるようなガス検
知素子を得るためにさらに研究を重ねた。その結果、s
no2とZnOとγ−Fe2O3を併用し、それらの併
用割合を下記の範囲に選ぶと、周囲湿度の影響も殆んど
受けず、しかもガス感度および濃度分離性に富んだガス
検知素子が得られることを見いだし、この発明を完成し
た。すなわち、この発明は、焼結体を備え、この焼結体
の電気抵抗変化が検知されることによつて、ガスの存在
を検知するようにしたガス検知素子であつて、焼結体は
、相互の組成比が下記のごとく設定された3種の金属酸
化物sno2、2noおよびγ−Fe2O3からなるこ
とを特徴とするガス検知素子をその要旨とするものであ
る。The inventors also found that the gas sensitivity, which is determined as described below as an indicator of the gas sensitivity of the gas detection element, is
Target values were set for each of concentration separation and humidity dependence (indicating susceptibility to ambient humidity) (gas sensitivity: 6).
5% or more, concentration separation: 1.70 or more, humidity dependence =
1.1±0.2) Further research was conducted to obtain a gas sensing element that would satisfy this target value. As a result, s
By using NO2, ZnO, and γ-Fe2O3 in combination and selecting their combined ratio within the range below, a gas detection element that is hardly affected by ambient humidity and has excellent gas sensitivity and concentration separation can be obtained. He discovered this and completed this invention. That is, the present invention is a gas detection element that includes a sintered body and detects the presence of gas by detecting a change in electrical resistance of the sintered body, the sintered body comprising: The gist thereof is a gas sensing element characterized by being composed of three types of metal oxides sno2, 2no and γ-Fe2O3 whose mutual composition ratios are set as follows.
SnO2:0.5〜90モル%
ZnO:0.5〜40モル%
γ−Fe2O3:0.5〜99モル%
これらの範囲は添付図のモル三角相図(第1図)に斜線
部分として表わされている。SnO2: 0.5-90 mol% ZnO: 0.5-40 mol% γ-Fe2O3: 0.5-99 mol% These ranges are shown as the shaded area in the attached molar triangular phase diagram (Figure 1). I'm being ignored.
つぎに、この発明を実施例にもとづき比較例と対照して
詳しく説明する。Next, the present invention will be described in detail based on Examples and in comparison with Comparative Examples.
すなわち、下記のようにして原料粉末を調製し、ガス検
知素子を製造した。That is, a raw material powder was prepared as described below, and a gas sensing element was manufactured.
SnO2:高純度金属スズ粒子を高純度硝酸中に徐々に
添加して白色沈澱物をつくつた。SnO2: High purity metallic tin particles were gradually added to high purity nitric acid to form a white precipitate.
つぎに、この白色沈澱物を乾燥し、さらに空気中で60
0℃×5時間仮焼してらいかい機で粉砕し微粉末状(比
表面積22イ/9)にした。これをSnO2原料粉末と
した。晶(戸田工業社製)を用いた。Next, this white precipitate was dried and further dried in air for 60 minutes.
The mixture was calcined at 0° C. for 5 hours and pulverized using a mill to form a fine powder (specific surface area: 22/9). This was used as SnO2 raw material powder. Crystal (manufactured by Toda Kogyo Co., Ltd.) was used.
上記の原料を後記の表の割合で配合し、この配合物を一
定量(20T19)秤量し、これを用いて白金電極を備
えた円柱状の素子用成形体(直径2mW!、長さ2mm
)を圧縮成形した。The above raw materials were blended in the proportions shown in the table below, a certain amount (20T19) of this blend was weighed, and this was used to form a cylindrical device molded body (diameter 2 mW!, length 2 mm) equipped with platinum electrodes.
) was compression molded.
つぎに、これを温度800℃、3時間、減圧下(10−
3mmHg)の条件で焼成した。この焼結体を冷却した
のち、さらに徐々に昇温させて空気雰囲気下において4
00℃で5時間保持(これによつてFe3O4はγ−F
e2O3になる)しガス検知素子を得た。つぎに、上記
のようにして得られたガス検知素子のガス感応特性をつ
ぎのようにして求めた。すなわち、ガス検知素子の周囲
にコイル状ヒータを配設し、これらをステンレススチー
ル製の金網キヤツプで覆つた。その状態でコイル状ヒー
タに通電してガス検知素子を加熱し、素子を3500C
および450℃の温度に保つた。そして、素子と直列に
固定抵抗を接続し、その両端に一定電圧(5V)を印加
し、固定抵抗両端の電圧を測定して次式によりつぎのよ
うにガス感応特性を求め、その結果を後記の表に示した
。表において、[F],0,[F],Q,[有]はそれ
ぞれ実施例の素子であり、それ以外のものは比較例の素
子である。なお、[F]とQとは同じ内容のものである
が、後の説明の都合により2個所に記載したものである
。〔ガス感応特性〕
1)ガス感度
(註)この値が大きい程感度が優れていることを示す。Next, this was heated at a temperature of 800°C for 3 hours under reduced pressure (10-
It was fired under conditions of 3 mmHg). After cooling this sintered body, the temperature was further gradually increased and the temperature was increased to
Hold at 00℃ for 5 hours (by this, Fe3O4 becomes γ-F
e2O3) to obtain a gas detection element. Next, the gas sensitivity characteristics of the gas sensing element obtained as described above were determined as follows. That is, a coiled heater was placed around the gas detection element, and these were covered with a stainless steel wire mesh cap. In this state, the coiled heater is energized to heat the gas detection element, and the element is heated to 3500C.
and maintained at a temperature of 450°C. Then, a fixed resistor is connected in series with the element, a constant voltage (5V) is applied across it, the voltage across the fixed resistor is measured, and the gas sensitivity characteristics are determined using the following formula, and the results are described below. It is shown in the table below. In the table, [F], 0, [F], Q, and [Yes] are elements of Examples, and the others are elements of Comparative Examples. Note that [F] and Q have the same content, but are written in two places for convenience of later explanation. [Gas Sensitivity Characteristics] 1) Gas Sensitivity (Note) The larger this value is, the better the sensitivity is.
2)ガス濃度分離性
(註)この値が大きい程ガス濃度分離性が優れているこ
とを示す。2) Gas concentration separation (Note) The larger this value is, the better the gas concentration separation is.
3)湿度依存性
(註)この値が1.0に近づく程湿度に対して影響を受
けない素子であることを示す。3) Humidity dependence (Note) The closer this value is to 1.0, the less affected by humidity it is.
ただし、
Rair:素子の空気中での抵抗値(露点13℃の湿度
下)RO.l:空気中のイソブタン濃度1,000pp
[nにおける素子の抵抗値(露点13゜Cの湿度下)R
7O.l:空気中のイソブタン濃度1,000PF1に
おける素子の抵抗値(露点30℃の湿度下)RO.3:
空気中のイソブタン濃度3,000ppIn?こおける
素子の抵抗値(露点13゜Cの湿度下)表より明らかな
ように、実施例のガス検知素子は、いずれも冒頭で説明
した目標値(ガス感度:65%以上、湿度依存性=1.
1±0.2、濃度分離2,性:1.70以上)を満たし
ていることがわかる。However, Rair: resistance value of the element in air (under humidity with a dew point of 13°C) RO. l: Isobutane concentration in air 1,000pp
[Resistance value of the element at n (under humidity with a dew point of 13°C) R
7O. l: resistance value of the element at an isobutane concentration in the air of 1,000 PF1 (under humidity with a dew point of 30°C) RO. 3:
Is the concentration of isobutane in the air 3,000 ppIn? As is clear from the table, the gas sensing elements of the examples all meet the target values explained at the beginning (gas sensitivity: 65% or more, humidity dependence = 1.
1±0.2, concentration separation 2, gender: 1.70 or more).
なお、γ−Fe2O3の含有量と湿度依存性とは下記の
ような関係を有することがわかる。すなわち、1sn0
21モルとZnO2モルの混合物に 3γ−Fe2
O3を、その量を次第に増加させながら添加したとき(
表のA−E)、2sn02単独物にγ−Fe2O3を、
その量を次第に増加させながら添加したとき(表のF−
1)、3Zn0単独物にγ−Fe2O3を、その量を次
3第に増加させながら添加したとき(表のJ−ぬ、4Z
n0を20モル%と一定にし、残部をSnO2とγ−F
e2O3とし、γ−Fe2O3の添加量を次第に増加し
たとき(表のN−Q)について、γ−Fe2O3の濃度
と湿度依存性との4関係を第2図に示した。It is understood that the content of γ-Fe2O3 and humidity dependence have the following relationship. That is, 1sn0
3γ-Fe2 in a mixture of 21 mol and ZnO2 mol
When O3 was added in increasing amounts (
A-E in the table), γ-Fe2O3 is added to 2sn02 alone,
When the amount is gradually increased (F- in the table)
1), when γ-Fe2O3 was added to 3Zn0 alone while increasing its amount (J-nu, 4Z in the table).
n0 is kept constant at 20 mol%, and the remainder is SnO2 and γ-F.
FIG. 2 shows four relationships between the concentration of γ-Fe2O3 and humidity dependence when the amount of γ-Fe2O3 added was gradually increased (N-Q in the table).
図において、曲線aは上記の1の場合を、曲線bは上記
の2の場合を、曲線cは上記の3の場合を、曲線dは上
記の4の場合を示している。第2図から明らかなように
、γ−Fe2O3の含有量を多くするに従つて素子の湿
度依存性はよくなつて1.0に近づくが、その含有量が
多くなりすぎると1.0から離れてゆくことがわかる。
また、γ−Fe2O3の含有量とガス感度の関係を第3
図に示した。In the figure, curve a shows case 1 above, curve b shows case 2 above, curve c shows case 3 above, and curve d shows case 4 above. As is clear from Fig. 2, as the content of γ-Fe2O3 increases, the humidity dependence of the device improves and approaches 1.0, but if the content becomes too large, it deviates from 1.0. I can see what will happen.
In addition, the relationship between the content of γ-Fe2O3 and gas sensitivity was
Shown in the figure.
第3図において、曲線a−dは、それぞれ第2図と同様
の場合を示している。第3図から明らかなように、γ−
Fe2O3の含有量を多くするに従つて急激にガス感度
は上昇するが、含有量が多くなりすぎるとガス感度が湿
度依存性の場合よりも激しく低下することがわかる。In FIG. 3, curves a to d represent the same cases as in FIG. 2, respectively. As is clear from Figure 3, γ−
It can be seen that as the content of Fe2O3 increases, the gas sensitivity rapidly increases, but when the content increases too much, the gas sensitivity decreases more sharply than in the case of humidity dependence.
第1図はこの発明のガス検知素子の組成範囲を示す三角
相図、第2図はγ−Fe2O3の含有量と湿度依存性の
関係を説明する説明図、第3図はγ−Fe2O3の含有
量とガス感度の関係を説明する説明図である。Figure 1 is a triangular phase diagram showing the composition range of the gas sensing element of the present invention, Figure 2 is an explanatory diagram explaining the relationship between the content of γ-Fe2O3 and humidity dependence, and Figure 3 is the content of γ-Fe2O3. It is an explanatory view explaining the relationship between quantity and gas sensitivity.
Claims (1)
れることによつて、ガスの存在を検知するようにしたガ
ス検知素子であつて、焼結体は、相互の組成比が下記の
ごとく設定された3種の金属酸化物、SnO_2、Zn
Oおよびγ−Fe_2O_3からなることを特徴とする
ガス検知素子。 SnO_2:0.5〜90モル% ZnO:0.5〜40モル% γ−Fe_2O_3:0.5〜99モル%[Claims] 1. A gas detection element comprising a sintered body and configured to detect the presence of gas by detecting a change in electrical resistance of the sintered body, the sintered body comprising: , three types of metal oxides, SnO_2, Zn, with mutual composition ratios set as follows.
A gas sensing element comprising O and γ-Fe_2O_3. SnO_2: 0.5-90 mol% ZnO: 0.5-40 mol% γ-Fe_2O_3: 0.5-99 mol%
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP841779A JPS5928861B2 (en) | 1979-01-26 | 1979-01-26 | gas detection element |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP841779A JPS5928861B2 (en) | 1979-01-26 | 1979-01-26 | gas detection element |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS55101040A JPS55101040A (en) | 1980-08-01 |
JPS5928861B2 true JPS5928861B2 (en) | 1984-07-16 |
Family
ID=11692545
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP841779A Expired JPS5928861B2 (en) | 1979-01-26 | 1979-01-26 | gas detection element |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5928861B2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6041312Y2 (en) * | 1979-06-23 | 1985-12-16 | 住友金属工業株式会社 | Short side adjustment device for continuous casting molds |
DE3048736C2 (en) * | 1980-12-23 | 1982-09-30 | GAO Gesellschaft für Automation und Organisation mbH, 8000 München | Identity card and process for its production |
JPS59168352A (en) * | 1983-03-15 | 1984-09-22 | Hitachi Ltd | Gas detection element and gas-leak warning device |
-
1979
- 1979-01-26 JP JP841779A patent/JPS5928861B2/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
JPS55101040A (en) | 1980-08-01 |
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