JPS62261948A - Production of self-exothermic type gas sensor - Google Patents
Production of self-exothermic type gas sensorInfo
- Publication number
- JPS62261948A JPS62261948A JP10560886A JP10560886A JPS62261948A JP S62261948 A JPS62261948 A JP S62261948A JP 10560886 A JP10560886 A JP 10560886A JP 10560886 A JP10560886 A JP 10560886A JP S62261948 A JPS62261948 A JP S62261948A
- Authority
- JP
- Japan
- Prior art keywords
- molding
- sensor
- silica
- breakdown
- polymerization
- 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
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims abstract description 20
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 12
- 238000000465 moulding Methods 0.000 claims abstract description 11
- 238000006116 polymerization reaction Methods 0.000 claims description 28
- 238000010304 firing Methods 0.000 claims description 26
- 238000010438 heat treatment Methods 0.000 claims description 19
- 238000001514 detection method Methods 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 3
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 60
- 239000000377 silicon dioxide Substances 0.000 abstract description 30
- 230000015556 catabolic process Effects 0.000 abstract description 22
- 230000007423 decrease Effects 0.000 abstract description 10
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 abstract description 6
- 238000001354 calcination Methods 0.000 abstract description 4
- 230000008859 change Effects 0.000 abstract description 3
- 238000007605 air drying Methods 0.000 abstract description 2
- 230000003247 decreasing effect Effects 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 37
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 30
- 239000000243 solution Substances 0.000 description 19
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 12
- 230000032683 aging Effects 0.000 description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 10
- 229910052739 hydrogen Inorganic materials 0.000 description 8
- 239000001257 hydrogen Substances 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 239000011230 binding agent Substances 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- UQMOLLPKNHFRAC-UHFFFAOYSA-N tetrabutyl silicate Chemical compound CCCCO[Si](OCCCC)(OCCCC)OCCCC UQMOLLPKNHFRAC-UHFFFAOYSA-N 0.000 description 5
- 235000006693 Cassia laevigata Nutrition 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 241000522641 Senna Species 0.000 description 4
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 4
- 229940124513 senna glycoside Drugs 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- IJKVHSBPTUYDLN-UHFFFAOYSA-N dihydroxy(oxo)silane Chemical compound O[Si](O)=O IJKVHSBPTUYDLN-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- 238000005342 ion exchange Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000178 monomer Substances 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- -1 Hydrogen ions Chemical class 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- QXYJCZRRLLQGCR-UHFFFAOYSA-N dioxomolybdenum Chemical compound O=[Mo]=O QXYJCZRRLLQGCR-UHFFFAOYSA-N 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- 239000001282 iso-butane Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- VLAPMBHFAWRUQP-UHFFFAOYSA-L molybdic acid Chemical compound O[Mo](O)(=O)=O VLAPMBHFAWRUQP-UHFFFAOYSA-L 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 229910008046 SnC14 Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QZPSXPBJTPJTSZ-UHFFFAOYSA-N aqua regia Chemical compound Cl.O[N+]([O-])=O QZPSXPBJTPJTSZ-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000003729 cation exchange resin Substances 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000000539 dimer Substances 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000011550 stock solution Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Abstract
Description
【発明の詳細な説明】
［発明の利用分野］
この発明は、金属酸化物半導体の抵抗値の変化を利用し
たガスセンサの製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of manufacturing a gas sensor that utilizes changes in the resistance value of a metal oxide semiconductor.
この発明で得られるガスセンサは、メタンやイソブタン
、水素等の可燃性ガスの検出や、ＣＯ等の棗に一ガスの
紛出２．−田いスご、）−Ａ（）ｌ（牢ス−［用語法］
この明細書において、自己発熱型ガスセンサとは、セン
サ内の検出電流による自己発熱とヒータとによりセンサ
を加熱するようにしたものにおいて、最大自己発熱量と
ヒータ電力との比が０．５以上のセンサを言う。なお我
国において用いられるガスセンサの大部分は、自己発熱
型のものである。The gas sensor obtained by this invention can detect flammable gases such as methane, isobutane, and hydrogen, and can detect flammable gases such as CO. -Taisugo,)-A()l(Jail-Sugo- [Terminology] In this specification, a self-heating type gas sensor is a gas sensor that heats the sensor by self-heating due to the detection current inside the sensor and a heater. This refers to a sensor in which the ratio of the maximum self-heating amount to the heater power is 0.5 or more.The majority of gas sensors used in Japan are of the self-heating type.
またブレークダウン（Ｂ、Ｄ）は、ガスセンサが高濃度
のガスに触れることにより生じるもので、ガス濃度が低
下してもセンサの抵抗値が増大せず、ガス中での値にと
どまりつづける現象をいう。ブレークダウンはガスが消
滅した際の応答に関するもので、自己発熱型のセンサで
のみ生じる。この現象は誤報の原因となるばかりでなく
、センサの熱的劣化の原因ともなる。Breakdown (B, D) occurs when the gas sensor comes into contact with a high concentration of gas, and is a phenomenon in which the resistance value of the sensor does not increase even when the gas concentration decreases and remains at the value in the gas. say. Breakdown refers to the response when gas disappears and only occurs in self-heating sensors. This phenomenon not only causes false alarms, but also causes thermal deterioration of the sensor.
［従来技術］
特公昭５０−２３，３１７号は、５ｎＯｔの結合剤とし
て低分子量のシリカを用いることを開示している。[Prior Art] Japanese Patent Publication No. 50-23,317 discloses the use of low molecular weight silica as a 5nOt binder.
その実施例では、Ｓｎｏｗに０．３ｗｔ％のＰｄを添加
し、Ｓｎｏｗと当型量のアルミナ骨材と混合し、一対の
ヒータ兼用電極を埋設した形状に成型する。In this example, 0.3 wt% of Pd is added to Snow, the Snow is mixed with an equivalent amount of alumina aggregate, and the mixture is molded into a shape in which a pair of heater electrodes are embedded.
ついで７００℃で予備焼成する。Then, it is pre-baked at 700°C.
７５ｃｃのテトラエチルシリケートを２５ｃｃの水と０
．３ｃｃの塩酸と混合し、３０分間熟成し、低分子量の
ケイ酸溶液を得る。ケイ酸溶液をセンサに含浸させ、６
００℃で焼成してガスセンサを完成する。75cc of tetraethyl silicate with 25cc of water
．． Mix with 3 cc of hydrochloric acid and age for 30 minutes to obtain a low molecular weight silicic acid solution. Impregnating the sensor with silicic acid solution, 6
The gas sensor is completed by firing at 00°C.
発明者らは、この製法で得たセンサを自己発熱型として
用いると、長時間の使用によりセンサの抵抗値が徐々に
低下することを見出だした（第１図Ａ）。低抵抗化は、
空気中の抵抗値に対しても、ガス中の抵抗値に対しても
生ずるが、その程度は、水素で最も大きく、エタノール
、イソブタンがこれに次ぎ、メタンではやや小さい。自
己発熱型以外のセンサでも、長時間使用すると抵抗値は
減少する。しかしその程度は、自己発熱型の方が大きい
。The inventors have discovered that when a sensor obtained by this manufacturing method is used as a self-heating type sensor, the resistance value of the sensor gradually decreases with long-term use (FIG. 1A). Lower resistance is
This occurs with respect to the resistance value in both air and gas, but the degree of resistance is greatest for hydrogen, followed by ethanol and isobutane, and slightly smaller for methane. Even with sensors other than self-heating type, the resistance value decreases when used for a long time. However, the extent of this is greater in the self-heating type.
［発明の課題］
この発明の課題は、（１）自己発熱型ガスセンサの経時
的低抵抗化の抑制と、（２）これに関連して生じるブレ
ークダウンの抑制、とに有る。[Problem of the Invention] The object of the present invention is to (1) suppress the resistance reduction over time of a self-heating type gas sensor, and (2) suppress the breakdown that occurs in connection with this.
［発明の構成コ
この発明の自己発熱型ガスセンサの製造方法は、ヒータ
兼用電極と検出電極とを埋設したＳｎＯ，の成型体を成
型し、この成型体を予備焼成した後、低分子量のケイ酸
溶液を成型体に含浸させ、成型体を本焼成してガスセン
サとする方法において、前記ケイ酸溶液中のケイ酸の平
均重合度を２〜３とし、かつ本焼成の温度を７００〜８
００℃、その時間を１０〜６０分としたことを特徴とす
る。[Structure of the Invention] The method for manufacturing a self-heating gas sensor of the present invention involves molding a molded body of SnO in which a heater electrode and a detection electrode are embedded, and pre-calcining this molded body. In the method of impregnating the molded body with a solution and firing the molded body to produce a gas sensor, the average degree of polymerization of the silicic acid in the silicic acid solution is set to 2 to 3, and the temperature of the main firing is set to 700 to 8.
00° C. for 10 to 60 minutes.
なおここに平均重合度とは、ケイ酸１分子当たりのケイ
素原子数の平均値を意味する。Note that the average degree of polymerization herein means the average number of silicon atoms per molecule of silicic acid.
発明者らは、自己発熱型ガスセンサの経時的低抵抗化の
抑制には、結合剤として加えたシリカの重合度の調製が
有効であることを見出だした。従来のセンナ、（特公昭
５０−２３，３１７号のもの）、では、ケイ酸溶液中の
シリカの平均重合度は約３．５である。そしてこれを３
以下とすることにより、低抵抗化をほぼ抑制することが
出来た。またケイ酸のモノマーが結合剤としての作用を
ほとんど持たず、結合剤としての作用はダイマー以上で
のみ生ずることも見出だした。さらにシリカの添加効果
は、その出発材料にはよらず、平均重合度のみで定まる
ことを見出だした。自己発熱型ガスセンサの経時特性は
、シリカの平均重合度を２〜３とすることにより改善さ
れる。 しかし発明者らは、シリカの平均重合度を２〜
３とすると、ブレークダウンが生じ易くなるという問題
に直面した。そして、シリカ添加後の本焼成条件を７０
０〜８００℃で、１０〜６０分とすれば、ブレークダウ
ンはほとんど生じないことを見出だした。The inventors have discovered that adjusting the degree of polymerization of silica added as a binder is effective in suppressing the resistance of a self-heating gas sensor from decreasing over time. In conventional senna (Japanese Patent Publication No. 50-23,317), the average degree of polymerization of silica in the silicic acid solution is about 3.5. and this 3
By setting the value below, it was possible to almost suppress the reduction in resistance. It was also discovered that silicic acid monomers have almost no binding agent action, and that binding agent action occurs only in dimers or higher. Furthermore, it has been found that the effect of adding silica is determined only by the average degree of polymerization, regardless of the starting material. The aging characteristics of the self-heating gas sensor are improved by setting the average degree of polymerization of silica to 2 to 3. However, the inventors have determined that the average degree of polymerization of silica is 2 to 2.
When setting it to 3, we encountered the problem that breakdown was more likely to occur. Then, the main firing conditions after adding silica were set to 70
It has been found that when the temperature is 0 to 800°C for 10 to 60 minutes, almost no breakdown occurs.
［実施例］
以下に、ケイ酸溶液の調製、センサの製造、経時特性、
ブレークダウン特性の順に実施例を説明する。[Example] Below, preparation of silicic acid solution, manufacturing of sensor, aging characteristics,
Examples will be described in order of breakdown characteristics.
（ケイ酸溶液の調製）
特公昭５０−２３．３１７号の方法で、ケイ酸溶液を調
製した。７５ｃｃのテトラエチルシリケートを２５ｃｃ
の水と０．３ｃｃの塩酸（８０１２０ｗｔ％）と混合し
、室温で熟成する。熟成の過程でテトラエチルシリケー
トは加水分解し、高分子量のケイ酸へと成長する。(Preparation of silicic acid solution) A silicic acid solution was prepared by the method disclosed in Japanese Patent Publication No. 50-23.317. 75cc of tetraethyl silicate to 25cc
of water and 0.3 cc of hydrochloric acid (80120 wt%) and aged at room temperature. During the aging process, tetraethylsilicate hydrolyzes and grows into high molecular weight silicic acid.
平均重合度への熟成時間の影響を測定した。シリカ溶液
にモリブデン酸（ＭｏＯ２の１〜２水和物）を加えると
、黄色に発色する。発色速度はシリカの平均重合度によ
り定まり、重合が進むと著しく低下する。この方法で求
めた平均重合度を表１に示す。The influence of aging time on the average degree of polymerization was determined. When molybdic acid (mono-dihydrate of MoO2) is added to a silica solution, it develops a yellow color. The color development rate is determined by the average degree of polymerization of silica, and decreases significantly as the polymerization progresses. Table 1 shows the average degree of polymerization determined by this method.
表１
熟成時間 平均重合度
ＯＩ モノマー
１５分 ２．５
３０分 ３．５
この結果から、従来技術でのシリカの平均重合度が、約
３．５であることが分かった。Table 1 Aging time Average degree of polymerization OI Monomer 15 minutes 2.5 30 minutes 3.5 From these results, it was found that the average degree of polymerization of silica in the conventional technique was about 3.5.
なお平均重合度のコントロールは、熟成時間の他に、水
の量やＰＨの調整によっても行うことが出来る。加える
水の量を増すと、加水分解が促進されて重合度が増す。Note that the average degree of polymerization can be controlled not only by aging time but also by adjusting the amount of water and pH. Increasing the amount of water added accelerates hydrolysis and increases the degree of polymerization.
溶液中の水素イオンは加水分解触媒として作用し、ＰＨ
をさらに下げても重合度は増す。また塩酸は、硝酸等の
任意の酸に代えることが出来ろ。Hydrogen ions in the solution act as a hydrolysis catalyst, increasing the pH
Even if the temperature is further lowered, the degree of polymerization increases. Furthermore, hydrochloric acid can be replaced with any acid such as nitric acid.
テトラブチルシリケート１００ｃｃを、７５ｃｃの水と
０．５ｃｃの塩酸（２０ｗｔ％）と混合する。これを室
温で熟成し、モリブデン酸の発色速度から平均重合度を
求めた。平均重合度と熟成時間との関係を表２に示す。100 cc of tetrabutyl silicate is mixed with 75 cc of water and 0.5 cc of hydrochloric acid (20 wt%). This was aged at room temperature, and the average degree of polymerization was determined from the rate of color development of molybdic acid. Table 2 shows the relationship between the average degree of polymerization and aging time.
表２
熟成時間 平均重合度
１０分 ２．５
３０分 ４
ケイ酸溶液の他の製法として、イオン交換法を検討した
。Table 2 Aging time Average degree of polymerization 10 minutes 2.5 30 minutes 4 As another method for producing a silicic acid solution, an ion exchange method was investigated.
メタケイ酸（ＮａｔＳｉＯｓ）の水溶液を、水素型の陽
イオン交換樹脂で処理する。この過程でナトリウムイオ
ンは水素イオンと交換され、モノケイ酸溶液が得られる
。０．３規定（溶液１リツトル中のシリカ量がモノケイ
酸換算で０．３モル）のシリカ溶液を得、塩酸でＰＨを
調整し、室温で熟成させた。このようにして平均重合度
２．２．５．３．５の３種のケイ酸溶液を得た。なお平
均重合度は氷点降下法で測定し、有効数字０．１まで測
定することが出来た。An aqueous solution of metasilicic acid (NatSiOs) is treated with a hydrogen type cation exchange resin. In this process, sodium ions are exchanged with hydrogen ions and a monosilicic acid solution is obtained. A silica solution of 0.3N (the amount of silica in 1 liter of solution is 0.3 mol in terms of monosilicic acid) was obtained, the pH was adjusted with hydrochloric acid, and the solution was aged at room temperature. In this way, three kinds of silicic acid solutions having an average degree of polymerization of 2.2.5.3.5 were obtained. The average degree of polymerization was measured by the freezing point depression method, and could be measured to an effective figure of 0.1.
（センサの製造）
ＳｎＣ１４をアンモニアで加水分解し、スズ酸のゾルと
する。ゾルに水を加えて、遠心分離法により遊離の塩素
イオンが検出できなくなるまで洗浄を繰り返す。洗浄後
のゾルを乾燥し、６００℃で空気中にて１時間焼成し５
ｎＯｔを得た。なおＳｎＯ２の製造条件は任意に変更で
き、特に焼成条件は、５００〜８００℃で３０分〜４時
間で有れば問題はない。また焼成雰囲気は、空気中等の
酸化性雰囲気、あるいはＮ、中等の中性雰囲気を用いる
ことができ、非還元性であれば良い。(Manufacture of sensor) SnC14 is hydrolyzed with ammonia to form a stannic acid sol. Water is added to the sol and washing is repeated until no free chloride ions can be detected by centrifugation. The washed sol was dried and baked in air at 600°C for 1 hour.
Obtained nOt. Note that the manufacturing conditions for SnO2 can be changed arbitrarily, and in particular, there is no problem as long as the firing conditions are at 500 to 800 DEG C. for 30 minutes to 4 hours. The firing atmosphere may be an oxidizing atmosphere such as air or a neutral atmosphere such as N, as long as it is non-reducing.
５ｎＯｔを粉砕し、Ｐｄの王水溶液を加えて、ＳｎＯ＊
１００ｇ当たり０．３ｇ（Ｐｄ換算）のＰｄを含浸させ
た。含浸後のＳｎｏｗを空気中で５００℃にて３０分加
熱し、Ｐｄ塩を熱分解して担トヂさせた。Grind 5nOt, add Pd aqua regia solution, and make SnO*
0.3 g (in terms of Pd) of Pd was impregnated per 100 g. The impregnated Snow was heated in air at 500° C. for 30 minutes to thermally decompose and support Pd salt.
なおＰｄは任意の貴金属触媒で置き換えることができ、
添加量はＳＳｎ０ｔ１当たり１ｇ以下とするのが好まし
い。Note that Pd can be replaced with any noble metal catalyst,
The amount added is preferably 1 g or less per SSn0t.
Ｐｄの添加後の５ｎＯｓを、当型量の１０００メツシユ
のアルミナと混合した。The 5nOs after addition of Pd was mixed with a typical amount of 1000 mesh alumina.
さらに変形例として、Ｐｄ無添加のもの、アルミナ無添
加のものを製造した。Furthermore, as a modified example, one without adding Pd and one without adding alumina were manufactured.
これらの材料を用いて、第２図のガスセンサを製造する
。図において、（２）はヒータ兼用電極、（４）は検出
電極で、それぞれＰｄ−１ｒ合金のコイルからなり、そ
の抵抗値は使用時で約２Ωである。Using these materials, the gas sensor shown in FIG. 2 is manufactured. In the figure, (2) is a heater electrode, and (4) is a detection electrode, each of which is made of a Pd-1r alloy coil, and has a resistance value of about 2Ω when in use.
電極（２）、（４”）をあらかじめステムに固定し、電
極（２）、（４）を埋設するように、半導体材料を塗布
する。次いで各電極（２）、（４）に通電することによ
り、７００℃で１０分間予備焼成し、半導体の成型体（
６）にシリカの含浸に耐えろ程度の強度を与える。なお
予備焼成は、シリカ溶液の含浸時に成型体（６）が分解
しないようにするためのらので、その条件は適宜に変更
できる。予備焼成の温度は好ましくは６００〜８５０℃
とし、時間は２分〜３０分とするのが好ましい。Electrodes (2) and (4") are fixed to the stem in advance, and a semiconductor material is applied so as to bury the electrodes (2) and (4). Next, each electrode (2) and (4) is energized. The semiconductor molded body (
6) Gives strength enough to withstand silica impregnation. Note that the preliminary firing is performed to prevent the molded body (6) from decomposing during impregnation with the silica solution, and the conditions thereof can be changed as appropriate. Prefiring temperature is preferably 600-850°C
The time is preferably 2 minutes to 30 minutes.
前記の各ケイ酸溶液を成型体（６）に所定の回数滴下し
、シリカを含浸させる。風乾後に、電極（２）、（４）
に通電し、７００〜８００℃にて、１０〜６０分間本焼
成を行う。雰囲気は空気中としたが、還元性でなければ
良い。滴下の回数はテトラエチルシリケートやテトラブ
チルシリケートを用いた乙のでは１回とし、イオン交換
法を用いたものでは２回とした。Each of the silicic acid solutions described above is dropped onto the molded body (6) a predetermined number of times to impregnate it with silica. After air drying, electrodes (2) and (4)
Electricity is applied to perform main firing at 700 to 800° C. for 10 to 60 minutes. The atmosphere was air, but it is fine as long as it is not reducing. The number of times of dropping was once for the sample using tetraethyl silicate or tetrabutyl silicate, and twice for the sample using the ion exchange method.
加えたシリカの約半量は成型体（６）の内部に浸透し、
他の半量は成型体（６）の表面に析出してシリカ波膜（
８）となる。シリカの濃度は、テトラエチルシリケート
やテトラブチルシリケートを用いた場合、成型体（６）
の内部でＳｎＯ，とアルミナの総量に対し３ｗｔ％であ
った。また成型体（６）を粉砕し全体を均一に混合して
シリカ濃度を測定すると、約５ｗｔ％で有った。イオン
交換法の場合、原液の濃度が０．３規定と希薄なので、
成型体（６）の内部で１ｗｔ％、全体で２ｗｔ％で有っ
た。Approximately half of the added silica penetrates into the molded body (6),
The other half is deposited on the surface of the molded body (6) and the silica wave film (
8). When using tetraethyl silicate or tetrabutyl silicate, the concentration of silica is as follows: molded product (6)
It was 3 wt% of the total amount of SnO and alumina inside. Furthermore, when the molded body (6) was pulverized, the whole was mixed uniformly, and the silica concentration was measured, it was found to be about 5 wt%. In the case of the ion exchange method, the concentration of the stock solution is as dilute as 0.3N, so
The content was 1 wt% inside the molded body (6) and 2 wt% overall.
本焼成条件を７５０℃、２０分としたものに付いて、セ
ンナの強度を測定した。結果を破断荷重として、表３に
示す。The strength of senna was measured under the main firing conditions of 750° C. for 20 minutes. The results are shown in Table 3 as breaking loads.
表３
平均重合度 シリカ原料 破断荷重シリカ無
添加＊５ｋｇｗ／ｃｍ”
１＊ メタケイ酸 ５ Ｉ２
９ Ｉ
２．５ 〃 ＩＯＩ３．５＊
〃 １０ 〃１＊テトラエチルシリケー
ト ６ Ｉ２．５ 〃 １１
Ｉ３．５＊ 〃 １１ Ｉ２．
５ テトラブチルシリケート １０〃＊ ＊ 印は比較
例。Table 3 Average degree of polymerization Silica raw material Breaking load Silica-free *5 kgw/cm” 1* Metasilicic acid 5 I2
9 I 2.5 IOI3.5*
〃 10 〃1*Tetraethylsilicate 6 I2.5 〃 11
I3.5* 〃 11 I2.
5 Tetrabutyl silicate 10〃* * Marked is a comparative example.
表からシリカの出発原料はセンサ（１０）の強度にあま
り関係しないこと、およびケイ酸のモノマーでは結合剤
としての効果がないことが分かる。It can be seen from the table that the starting material of silica does not significantly affect the strength of the sensor (10) and that the silicic acid monomer is not effective as a binder.
また重合度は２以上で有れば良いことも分かる。It is also understood that the degree of polymerization should be 2 or more.
（経時特性）
得られたセンサ（１０）を１０個ずつ用い、第３図の回
路により特性を測定した。測定は清浄空気、および各３
５００ ｐｐ請のガスを用い、２０℃で相対湿度６５％
の雰囲気中で行った。結果は１０個のセンサの平均値で
現す。(Characteristics over time) The characteristics were measured using the circuit shown in FIG. 3 using ten of the obtained sensors (10). Measurements were made with clean air and 3
Using 500 PP gas at 20°C and 65% relative humidity.
I went there in an atmosphere of The results are expressed as the average value of 10 sensors.
図において（Ｉ２）は出力１００Ｖの商用電源で、トラ
ンス（１４）を介して１．ＩＶのヒータ電源を取り出し
、ヒータ兼用電極（２）に接続する。また電源（Ｉ２）
に、センサ（１０）と３．５にΩの負荷抵抗（１６）と
を接続し、負荷抵抗（１６）への出力からセンサ特性を
評価する。この場合にヒータ電力は６００５ｗで、最大
自己発熱はセンサ抵抗が３゜５にΩの時に生じ、８６０
ｏ＋ｗである。またセンサ（１０）の温度は空気中で３
００℃、最大自己発熱時で５５０℃である。In the figure, (I2) is a commercial power supply with an output of 100V, which is connected to 1.0V through a transformer (14). Take out the IV heater power source and connect it to the heater electrode (2). Also power supply (I2)
A load resistor (16) of 3.5Ω is connected to the sensor (10), and the sensor characteristics are evaluated from the output to the load resistor (16). In this case, the heater power is 6005W, and the maximum self-heating occurs when the sensor resistance is 3°5Ω, 860W.
It is o+w. Also, the temperature of the sensor (10) is 3.
00°C, and 550°C at maximum self-heating.
これとは別に８０ｖの電圧を、センサ（１０）と４にΩ
の負荷抵抗（１６）に印加するようにしたものを用いた
。ヒータ電力は６００ ｍｙ、最大自己発熱は４００ｍ
ｗである。Separately, apply a voltage of 80V to the sensor (10) and 4Ω.
The voltage was applied to the load resistor (16). Heater power is 600 m, maximum self-heating is 400 m
It is w.
各センサを１００Ｖの電圧を印加した回路で５００日間
連続通電し、その間の抵抗値の経時的変化を第１図（Ａ
）、（Ｂ）に示す。結果は通電開始１０日口のメタン３
５００ｐｐｍ中での抵抗値を１とし、それとの比で示す
。Each sensor was continuously energized for 500 days using a circuit that applied a voltage of 100 V, and the changes in resistance value over time during that time were plotted in Figure 1 (A
) and (B). The result is methane 3 on the 10th day after starting electricity.
The resistance value at 500 ppm is assumed to be 1, and the resistance value is expressed as a ratio.
第１図（Ａ）に、重合度３．５のテトラエチルシリケー
トを用いたセンサの特性を示す。なお最初のメタン中で
の抵抗値は３．６にΩであった。すべてのガスに対して
、センサの抵抗値は徐々に低下し、その程度は水素やエ
タノールに対して著しく、メタンではやや小さい。そし
てこれらの抵抗値の低下は、ガスの検出精度を低下させ
る。なおＣＯ中での抵抗値は、通電開始１０日口の１２
にΩ、５００日目フタにΩであった。FIG. 1(A) shows the characteristics of a sensor using tetraethyl silicate with a degree of polymerization of 3.5. The initial resistance value in methane was 3.6Ω. For all gases, the resistance of the sensor gradually decreases, the degree of which is significant for hydrogen and ethanol, and slightly less for methane. A decrease in these resistance values reduces gas detection accuracy. Note that the resistance value in CO is 12
It was Ω on the lid on the 500th day.
第１図（Ｂ）に、重合度２．５のテトラエチルシリケー
トからのシリカを用いたセンサの経時特性を示す。なお
最初のメタン中での抵抗値は４．５にΩであった。この
例でも、センサの抵抗値は徐々に低下するが、その程度
は第１図（Ａ）の場合に比べはるかに小さい。またＣＯ
中での抵抗値は最初！０にΩで、５００日目フタ９にΩ
となった。FIG. 1(B) shows the aging characteristics of a sensor using silica made from tetraethylsilicate with a degree of polymerization of 2.5. The initial resistance value in methane was 4.5Ω. In this example as well, the resistance value of the sensor gradually decreases, but to a much smaller extent than in the case of FIG. 1(A). Also CO
The resistance value inside is the first! Ω on 0, Ω on lid 9 on the 500th day
It became.
各種のセンサに付いての経時特性を表４に示す。Table 4 shows the aging characteristics of various sensors.
結果は、通電開始５００日後のメタンや水素中の抵抗値
と、通電開始１０日口のメタンや水素中での抵抗値との
比で示す。なお試料１６の９００℃で本焼成したものに
付いては、ＳｎＯ２の抵抗値が高いため、Ｓｎｏｗとア
ルミナとの混合比を３＝２とした。The results are shown as a ratio of the resistance value in methane or hydrogen 500 days after the start of current application to the resistance value in methane or hydrogen 10 days after the start of current application. Note that for sample 16 which was main fired at 900° C., the mixing ratio of Snow and alumina was set to 3=2 because the resistance value of SnO2 was high.
表４の試料１〜３から、経時変化の主因は結合剤として
加えたシリカに有ること、およびシリカの平均重合度を
下げると経時特性を改善し得ることが分かる。次に試料
４〜８の比較から、シリカの効果は出発材料にはよらず
、平均重合度のみで定まることが分かる。From Samples 1 to 3 in Table 4, it can be seen that the main cause of the change over time is the silica added as a binder, and that the aging characteristics can be improved by lowering the average degree of polymerization of silica. Next, from a comparison of Samples 4 to 8, it can be seen that the effect of silica does not depend on the starting material, but is determined only by the average degree of polymerization.
試料１３〜１６から、本焼成の温度あるいは時間を増す
と、センサが経時的に高抵抗化することが分かった。そ
してこの現象は、焼成時間を６０分以上とする（試料１
４）、あるいは８００℃以上とする（試料１６）ことに
より生ずる。従って、本焼成は７００〜８００℃で、１
０〜６０分とする必要がａる。From Samples 13 to 16, it was found that as the temperature or time of main firing was increased, the resistance of the sensor became higher over time. This phenomenon occurs when the firing time is 60 minutes or more (Sample 1
4) or when the temperature is 800°C or higher (sample 16). Therefore, the main firing was performed at 700 to 800°C for 1
It is necessary to set it to 0 to 60 minutes.
（ブレークダウン特性）
第４図に、テトラエチルシリケートを用い、本焼成を６
００℃で１０分間としたセンサの、加熱温度と抵抗値と
の関係を示す。ここではジュール熱による加熱は行わず
、２つの電極（２）、（４）をいずれもヒータと兼用し
、センサを均一に加熱する。５５０℃でのメタン中の抵
抗値（４，ｌＫΩ）を基準として、各ガスへの抵抗値を
示す。なおガス濃度はいずれも３５００ｐｐｍである。(Breakdown characteristics) Figure 4 shows that tetraethyl silicate was used and the main firing was carried out for 6
The relationship between heating temperature and resistance value of a sensor heated at 00° C. for 10 minutes is shown. Here, heating by Joule heat is not performed, and both of the two electrodes (2) and (4) are used as heaters to uniformly heat the sensor. The resistance values for each gas are shown based on the resistance value in methane at 550°C (4,1KΩ). Note that the gas concentration was 3500 ppm in both cases.
高温域において空気中の抵抗値が著しく低下する点に、
このセンナの特徴がある。そしてこれがブレークダウン
の原因で有る。即ち実際の使用回路において、センサが
ガスに触れると、自己発熱によりセンナは高温へ加熱さ
れろ。ここで空気中とガス中との抵抗値の差が小さいた
め、ガスがなくなってもセンサは高温に加熱され続け、
抵抗値ら低下しない。この現象がブレークダウンである
。The point that the resistance value in the air decreases significantly in the high temperature range,
This senna has its characteristics. And this is the cause of the breakdown. That is, in an actual circuit, when the sensor comes into contact with gas, the senna will be heated to a high temperature due to self-heating. Since the difference in resistance between air and gas is small, the sensor continues to be heated to a high temperature even when the gas runs out.
The resistance value does not decrease. This phenomenon is breakdown.
なおブレークダウンはガスに触れると必ず生じるのでは
なく、他の原因とあいまって生じるのでＩ＋ｌ乙−１−
の上うなＭ円２１．ては−雷師雷庄の変動やトランス（
１４）の不適切さのため、センサの温度が高温側ヘシフ
トしている、あるいは周囲の温湿度が高く、センサの出
力が低抵抗側ヘシフトしている、等が有る。Note that breakdown does not always occur when exposed to gas, but occurs in combination with other causes, so I+l-1-
Upper eel M circle 21. What is the fluctuation and trance of Raishi Raisho (
Due to the inappropriateness of 14), the temperature of the sensor may be shifted to the high temperature side, or the ambient temperature and humidity may be high, and the output of the sensor may be shifted to the low resistance side.
第５図に、テトラエチルシリケートを用い、７５０℃で
２０分間本焼成したセンサの、温度と抵抗値との関係を
示す。なお抵抗の基準値（メタン３５００ ｐｐｍ）は
４．５にΩである。本焼成温度を増すことにより、空気
に対する温度特性が変化し、ブレークダウンが生じにく
くなっていることが分かる。FIG. 5 shows the relationship between temperature and resistance value of a sensor made of tetraethyl silicate and fired at 750° C. for 20 minutes. Note that the standard value of resistance (methane 3500 ppm) is 4.5Ω. It can be seen that by increasing the main firing temperature, the temperature characteristics with respect to air change and breakdown becomes less likely to occur.
第６図に、本焼成温度とブレークダウンとの関係を示す
。試料はいずれもテトラエチルシリケート（Ｄ、Ｐ２．
５）を用い、各温度で２０分焼成したものである。縦軸
に６００℃での空気とメタン３５００ｐｐｍ中との抵抗
値の比を示す。またブレークダウンを起こり易くするた
め第３図の商用電源（Ｉ２）をｌｌ０Ｖとして、５００
０ｐｐｍのメタンに５分間さらす。メタンを除いた後、
５分後の抵抗値がメタン換算で２０００ ｐｐｍ以上の
ものをブレークダウンと評価する。５０個のセンサに付
いて、ブレークダウンが生じろ確率を示す。図から本焼
成温度を７００℃以上とすることにより、ブレークダウ
ンを防止できることが分かる。FIG. 6 shows the relationship between main firing temperature and breakdown. All samples were tetraethyl silicate (D, P2.
5) and baked at each temperature for 20 minutes. The vertical axis shows the ratio of resistance values in air at 600°C and in 3500 ppm methane. In addition, in order to make breakdown easier to occur, the commercial power supply (I2) in Figure 3 is set to 110V, and the
Exposure to 0 ppm methane for 5 minutes. After removing methane,
A resistance value of 2000 ppm or more in terms of methane after 5 minutes is evaluated as breakdown. The probability of breakdown occurring for 50 sensors is shown. It can be seen from the figure that breakdown can be prevented by setting the main firing temperature to 700° C. or higher.
表５に、７５０℃での焼成時間と、ブレークダウン頻度
との関係を示す。測定方法は第６図の場合と同様である
。Table 5 shows the relationship between firing time at 750°C and breakdown frequency. The measurement method is the same as in the case of FIG.
表５
焼成時間 Ｒａ１ｒ／Ｒメタン Ｂ、Ｄ（％）３分
＊ ２．６ １０
１５分 ３．８２
２０分 ４．７ ０
４０分 ４．５０
１２０分水４０
＊ ＊印は比較例、いずれらテトラエチルシリケート原
料。Table 5 Firing time Ra1r/R methane B, D (%) 3 minutes* 2.6 10 15 minutes 3.82 20 minutes 4.7 0 40 minutes 4.50 120 minutes Water 40 * *marked is a comparative example, none Tetraethylsilicate raw material.
このように、焼成を７００℃以上で、１０分以上行えば
、ブレークダウンを防止することが出来る。しかし８０
０℃以上での焼成や、１２０分以上の焼成時間は、セン
サの経時特性を損ねる。なお発明者は、テトラブチルシ
リケートやメタケイ酸を材料とするものに付いても、焼
成条件とブレークダウン特性との関係を検討したが、結
果は第６図や表５のものと同等で有った。As described above, breakdown can be prevented by performing firing at 700° C. or higher for 10 minutes or longer. But 80
Firing at a temperature of 0° C. or higher or a firing time of 120 minutes or more impairs the aging characteristics of the sensor. The inventor also investigated the relationship between firing conditions and breakdown characteristics for materials made of tetrabutyl silicate and metasilicic acid, and the results were similar to those in Figure 6 and Table 5. Ta.
［発明の効果コ
この発明では、ガスセンサの経時変化を抑制すると共に
、ブレークダウンの防止が出来る。[Effects of the Invention] According to the present invention, it is possible to suppress deterioration of the gas sensor over time and to prevent breakdown.
第１図（Ａ）は従来例のガスセンサの特性図、第１図（
Ｂ）は実施例のガスセンサの特性図である。
第２図は実施例のガスセンサの部分切り欠き部付き平面
図、第３図はガスセンサの付帯回路を現す回路図である
。第４図は従来例のガスセンサの特性図である。第５図
、第６図は、実施例のガスセンサの特性図である。
図において、
（２） ヒータ兼用電極、 （４）検出電極、（６
） ＳｎＯ＊成型体、 （８）シリカ破膜、（
１０） ガスセンサ。Figure 1 (A) is a characteristic diagram of a conventional gas sensor;
B) is a characteristic diagram of the gas sensor of the example. FIG. 2 is a plan view with a partial cutout of the gas sensor of the embodiment, and FIG. 3 is a circuit diagram showing an auxiliary circuit of the gas sensor. FIG. 4 is a characteristic diagram of a conventional gas sensor. 5 and 6 are characteristic diagrams of the gas sensor of the example. In the figure, (2) heater electrode, (4) detection electrode, (6
) SnO* molded body, (8) ruptured silica membrane, (
10) Gas sensor.
Claims (1)
２の成型体を成型し、この成型体を予備焼成した後、低
分子量のケイ酸溶液を成型体に含浸させ、成型体を本焼
成してガスセンサとする方法において、 前記ケイ酸溶液中のケイ酸の平均重合度を２〜３とし、 かつ本焼成の温度を７００〜８００℃、本焼成の時間を
１０〜６０分としたことを特徴とする自己発熱型ガスセ
ンサの製造方法。(1) SnO with embedded heater electrode and detection electrode
In the method of molding the molded body of No. 2, preliminarily firing the molded body, impregnating the molded body with a low molecular weight silicic acid solution, and main firing the molded body to produce a gas sensor, the silicate in the silicic acid solution is A method for manufacturing a self-heating gas sensor, characterized in that the average degree of polymerization of the acid is 2 to 3, the temperature of the main firing is 700 to 800°C, and the time of the main firing is 10 to 60 minutes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10560886A JPS62261948A (en) | 1986-05-08 | 1986-05-08 | Production of self-exothermic type gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10560886A JPS62261948A (en) | 1986-05-08 | 1986-05-08 | Production of self-exothermic type gas sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62261948A true JPS62261948A (en) | 1987-11-14 |
| JPH0569378B2 JPH0569378B2 (en) | 1993-09-30 |
Family
ID=14412216
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10560886A Granted JPS62261948A (en) | 1986-05-08 | 1986-05-08 | Production of self-exothermic type gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62261948A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008046091A (en) * | 2006-08-21 | 2008-02-28 | Fis Inc | Hydrogen gas sensor |
| CN105784786A (en) * | 2015-01-09 | 2016-07-20 | 罗伯特·博世有限公司 | Sensor Device Used For Detecting Gas State Analytes And Manufacture Method Thereof |
-
1986
- 1986-05-08 JP JP10560886A patent/JPS62261948A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008046091A (en) * | 2006-08-21 | 2008-02-28 | Fis Inc | Hydrogen gas sensor |
| CN105784786A (en) * | 2015-01-09 | 2016-07-20 | 罗伯特·博世有限公司 | Sensor Device Used For Detecting Gas State Analytes And Manufacture Method Thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0569378B2 (en) | 1993-09-30 |
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