JPH07209235A - Thick film type gas sensor - Google Patents
Thick film type gas sensorInfo
- Publication number
- JPH07209235A JPH07209235A JP179494A JP179494A JPH07209235A JP H07209235 A JPH07209235 A JP H07209235A JP 179494 A JP179494 A JP 179494A JP 179494 A JP179494 A JP 179494A JP H07209235 A JPH07209235 A JP H07209235A
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- JP
- Japan
- Prior art keywords
- oxide
- gas sensor
- thick film
- layer
- gas
- 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.)
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- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明はＬＰガス，都市ガス，
水素ガス等を検出するガス漏れ警報器用の厚膜型ガスセ
ンサに係り、特に厚膜型ガスセンサの第一の酸化燃焼層
と第二の酸化燃焼層の構成に関する。BACKGROUND OF THE INVENTION This invention relates to LP gas, city gas,
The present invention relates to a thick film gas sensor for a gas leak alarm that detects hydrogen gas and the like, and more particularly to a configuration of a first oxidation combustion layer and a second oxidation combustion layer of a thick film gas sensor.
【０００２】[0002]
【従来の技術】ガスセンサの一つとして酸化スズや酸化
亜鉛等の金属酸化物半導体を用いるものが知られてい
る。これら金属酸化物半導体は大気中において３００な
いし５００℃程度に加熱されると粒子表面に大気中の酸
素が活性化吸着し、高抵抗化するが還元性ガスである被
検ガス中では還元性ガスが吸着酸素に替えて金属酸化物
半導体に吸着され電気抵抗値が減少する。このような性
質を利用して金属酸化物半導体を利用するガスセンサが
ＬＰガスや都市ガス等のガス漏れ警報器用に利用されて
いる。2. Description of the Related Art As one of gas sensors, one using a metal oxide semiconductor such as tin oxide or zinc oxide is known. When these metal oxide semiconductors are heated to about 300 to 500 ° C. in the atmosphere, oxygen in the atmosphere is activated and adsorbed on the particle surface to increase the resistance, but the reducing gas is a reducing gas in the test gas which is a reducing gas. Is adsorbed on the metal oxide semiconductor instead of adsorbed oxygen, and the electric resistance value is reduced. A gas sensor using a metal oxide semiconductor by utilizing such a property is used for a gas leak alarm device for LP gas, city gas, or the like.
【０００３】図５は従来の厚膜型ガスセンサを示す平面
図である。図６は従来の厚膜型ガスセンサを示す図５の
Ｂ−Ｂ矢視断面図である。従来の厚膜型ガスセンサはア
ルミナ等の絶縁性基板１の一主面上に第二の酸化燃焼層
３Ｂと感ガス層４と第一の酸化燃焼層３Ａを積層して形
成される。基板１の他の主面にはヒータ８が形成され厚
膜型ガスセンサを所定の温度に加熱する。感ガス層４は
例えば酸化スズ等のｎ型金属酸化物半導体からなる層で
ある。第一と第二の酸化燃焼層３Ａ，３Ｂは酸化スズに
白金のような貴金属触媒を担持して形成される。これら
の酸化燃焼層３Ａ，３Ｂは可燃性ガスに対する選択性を
高めてアルコール等を選択的に燃焼させる。感ガス層４
またはヒータ８には電極２，２Ａを介して商用電源が直
接的に印加される。FIG. 5 is a plan view showing a conventional thick film type gas sensor. FIG. 6 is a sectional view taken along the line BB of FIG. 5 showing a conventional thick film gas sensor. A conventional thick film gas sensor is formed by laminating a second oxidative combustion layer 3B, a gas sensitive layer 4 and a first oxidative combustion layer 3A on one main surface of an insulating substrate 1 made of alumina or the like. A heater 8 is formed on the other main surface of the substrate 1 to heat the thick film gas sensor to a predetermined temperature. The gas sensitive layer 4 is a layer made of an n-type metal oxide semiconductor such as tin oxide. The first and second oxidation combustion layers 3A and 3B are formed by supporting a noble metal catalyst such as platinum on tin oxide. These oxidative combustion layers 3A and 3B enhance selectivity with respect to combustible gas and selectively burn alcohol or the like. Sensitive gas layer 4
Alternatively, a commercial power source is directly applied to the heater 8 via the electrodes 2 and 2A.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら上述のよ
うな従来の三層型の厚膜型ガスセンサは電源電圧の変動
により厚膜型ガスセンサの温度が上昇し、そのためにセ
ンサの抵抗値が減少して雰囲気に可燃性ガスが存在しな
いときに警報を発するという問題があった。さらに従来
の三層型の厚膜型ガスセンサは白金のような貴金属触媒
を担持しているためにエージング期間が長くなり、可燃
性ガス中で経時的に徐徐に抵抗値が減少するという問題
があった。However, in the conventional three-layer type thick film type gas sensor as described above, the temperature of the thick film type gas sensor rises due to the fluctuation of the power supply voltage, and the resistance value of the sensor decreases accordingly. There is a problem that an alarm is issued when flammable gas does not exist in the atmosphere. Furthermore, the conventional three-layer thick-film gas sensor has a problem that the aging period becomes long because it carries a precious metal catalyst such as platinum, and the resistance value gradually decreases with time in a flammable gas. It was
【０００５】この発明は上述の点に鑑みてなされ、その
目的は酸化燃焼層の触媒を改良することにより、電圧変
動時の抵抗値の変動が少なく、エージング期間が短い上
に、抵抗値が経時的に安定な厚膜型ガスセンサを提供す
ることにある。The present invention has been made in view of the above points, and an object thereof is to improve a catalyst of an oxidation combustion layer so that the resistance value does not fluctuate little when the voltage fluctuates, the aging period is short, and the resistance value elapses with time. The object of the present invention is to provide a thick film type gas sensor that is stable.
【０００６】[0006]
【課題を解決するための手段】上述の目的はこの発明に
よれば、金属酸化物半導体の抵抗値の変化を利用してガ
スの有無を検出する厚膜型ガスセンサであって、（１）
基板と、（２）一対の電極と、（３）第一の酸化燃焼層
と、（４）感ガス層と、（５）第二の酸化燃焼層と、
（６）ヒータを包含し、基板はガスセンサの支持体であ
り、一対の電極は基板上に離間して直接的に被着され、
第二の酸化燃焼層は基板と一対の電極上に選択的に積層
され、感ガス層は第二の酸化燃焼層と一対の電極上に選
択的に積層され、第一の酸化燃焼層は感ガス層の全部を
被覆して積層され、第一の酸化燃焼層はｎ型金属酸化物
半導体からなる担体に酸化ニッケル，酸化鉄，酸化アル
ミニウム，酸化クロムの群から選ばれた少なくとも一つ
と貴金属を触媒として担持してなり、第二の酸化燃焼層
はｎ型金属酸化物半導体からなる担体に酸化ニッケル，
酸化鉄，酸化アルミニウム，酸化クロムの群から選ばれ
た少なくとも一つと貴金属を触媒として均一に担持して
なり、感ガス層はｎ型金属酸化物半導体からなり、ヒー
タは前記基板上に積層されて厚膜型ガスセンサを所定の
温度に加熱するものであるとすることにより達成され
る。According to the present invention, there is provided a thick film type gas sensor for detecting the presence / absence of a gas by utilizing a change in the resistance value of a metal oxide semiconductor.
A substrate, (2) a pair of electrodes, (3) a first oxidative combustion layer, (4) a gas sensitive layer, (5) a second oxidative combustion layer,
(6) A heater is included, the substrate is a support for the gas sensor, and the pair of electrodes are directly deposited on the substrate with a space therebetween.
The second oxidative combustion layer is selectively laminated on the substrate and the pair of electrodes, the gas-sensitive layer is selectively laminated on the second oxidative combustion layer and the pair of electrodes, and the first oxidative combustion layer is the sensitive layer. The first oxidation combustion layer is laminated by covering the entire gas layer, and at least one selected from the group of nickel oxide, iron oxide, aluminum oxide and chromium oxide and a noble metal are formed on a carrier composed of an n-type metal oxide semiconductor. The second oxidation combustion layer is supported as a catalyst, and the second oxidation combustion layer is a support made of an n-type metal oxide semiconductor and nickel oxide,
At least one selected from the group consisting of iron oxide, aluminum oxide, and chromium oxide and a noble metal are uniformly supported as a catalyst, the gas-sensitive layer is made of an n-type metal oxide semiconductor, and the heater is laminated on the substrate. This is achieved by heating the thick film gas sensor to a predetermined temperature.
【０００７】酸化燃焼層はアルコール等の干渉ガスを酸
化燃焼して厚膜型ガスセンサに対する干渉ガスの影響を
なくす。感ガス層はＬＰガス等の被検ガスを吸着して電
気抵抗値を減少し被検ガスを検出する。The oxidizing combustion layer oxidizes and burns the interference gas such as alcohol to eliminate the influence of the interference gas on the thick film type gas sensor. The gas sensitive layer adsorbs a test gas such as LP gas to reduce the electric resistance value and detect the test gas.
【０００８】[0008]
【作用】第一の酸化燃焼層または第二の酸化燃焼層に含
有された酸化ニッケル，酸化鉄，酸化アルミニウム，酸
化クロム等の酸化物は貴金属とともに感ガス層のｎ型金
属酸化物半導体が酸素吸着する際の触媒として機能す
る。酸化ニッケル，酸化鉄，酸化アルミニウム，酸化ク
ロム等の酸化物と貴金属が担持された酸化燃焼層から感
ガス層のｎ型金属酸化物半導体への酸素供給は貴金属の
みが担持された酸化燃焼層の特性に比してより高温に至
るまで良好である。[Function] Oxides such as nickel oxide, iron oxide, aluminum oxide, and chromium oxide contained in the first oxidation combustion layer or the second oxidation combustion layer are noble metals and the n-type metal oxide semiconductor in the gas-sensitive layer is oxygen. It functions as a catalyst for adsorption. Oxygen is supplied to the n-type metal oxide semiconductor of the gas-sensitive layer from the oxidation combustion layer supporting oxides of nickel oxide, iron oxide, aluminum oxide, chromium oxide and the like and noble metal in the oxidation combustion layer supporting only noble metal. Good up to a higher temperature than the characteristics.
【０００９】また酸化ニッケル，酸化鉄，酸化アルミニ
ウム，酸化クロム等の酸化物と貴金属がｎ型金属酸化物
半導体に均一に担持されるために触媒活性の増大と安定
化がもたらされる。ｎ型金属酸化物半導体に酸化ニッケ
ル，酸化鉄，酸化アルミニウム，酸化クロム等の酸化物
を混合したあとで貴金属がこれらの混合物に担持される
ので、酸化ニッケル，酸化鉄，酸化アルミニウム，酸化
クロム等の酸化物と貴金属がｎ型金属酸化物半導体に均
一に分散される。Further, since oxides of nickel oxide, iron oxide, aluminum oxide, chromium oxide and the noble metal are uniformly supported on the n-type metal oxide semiconductor, the catalytic activity is increased and stabilized. After mixing oxides of nickel oxide, iron oxide, aluminum oxide, chromium oxide, etc. into the n-type metal oxide semiconductor, the noble metal is supported on these mixtures, so nickel oxide, iron oxide, aluminum oxide, chromium oxide, etc. Oxide and the noble metal are uniformly dispersed in the n-type metal oxide semiconductor.
【００１０】[0010]
【実施例】次にこの発明の実施例を図面に基づいて説明
する。 実施例１ 図１はこの発明の実施例に係る厚膜型ガスセンサを示す
平面図である。図２はこの発明の実施例に係る厚膜型ガ
スセンサを示す図１のＡ−Ａ矢視断面図である。Embodiments of the present invention will now be described with reference to the drawings. Embodiment 1 FIG. 1 is a plan view showing a thick film type gas sensor according to an embodiment of the present invention. 2 is a sectional view taken along the line AA of FIG. 1 showing a thick film type gas sensor according to an embodiment of the present invention.
【００１１】従来の厚膜型ガスセンサと同一の機能を営
む部分は同一の符合を用いている。この発明の実施例に
係る厚膜型ガスセンサの構造は次の通りである。基板１
の一主面上に離間して二つの電極２が設けられる。基板
１と電極２の上に第二の酸化燃焼層３Ｙが選択的に設け
られる。第二の酸化燃焼層３Ｙと電極２の上に感ガス層
４が選択的に形成される。感ガス層４を完全に被覆して
第一の酸化燃焼層３Ｘが設けられる。電極２にリード線
７が接続される。基板１の他の主面には電極２Ａが形成
され、電極２Ａと基板１の上に選択的にヒータ８が形成
され、電極２Ａにはリード線９が接続される。Parts having the same functions as those of the conventional thick film type gas sensor have the same reference numerals. The structure of the thick film type gas sensor according to the embodiment of the present invention is as follows. Board 1
Two electrodes 2 are provided on one main surface with a space therebetween. A second oxidative combustion layer 3Y is selectively provided on the substrate 1 and the electrode 2. The gas sensitive layer 4 is selectively formed on the second oxidative combustion layer 3Y and the electrode 2. A first oxidative combustion layer 3X is provided by completely covering the gas sensitive layer 4. The lead wire 7 is connected to the electrode 2. An electrode 2A is formed on the other main surface of the substrate 1, a heater 8 is selectively formed on the electrode 2A and the substrate 1, and a lead wire 9 is connected to the electrode 2A.
【００１２】基板１は厚さ０．５ｍｍで縦３ｍｍ、横３
ｍｍの研磨されたアルミナ基板である。ヒータは酸化ル
テニウム抵抗体からなる。このような厚膜型ガスセンサ
は次のようにして調製される。基板１の二つの主面に白
金電極ペーストを所定のパターンでスクリーン印刷し、
乾燥後約１１００℃の温度で焼成した。酸化ルテニウム
からなるヒータ用ペーストを所定のパターンでスクリー
ン印刷し焼成した。The substrate 1 has a thickness of 0.5 mm and a length of 3 mm and a width of 3 mm.
mm polished alumina substrate. The heater comprises a ruthenium oxide resistor. Such a thick film type gas sensor is prepared as follows. Screen printing a platinum electrode paste on the two main surfaces of the substrate 1 in a predetermined pattern,
After drying, it was baked at a temperature of about 1100 ° C. A heater paste made of ruthenium oxide was screen-printed in a predetermined pattern and fired.
【００１３】スズ酸粉体を乾燥し、得られたスズ酸粉体
に酸化ニッケルNiO を５００ｐｐｍの割合で添加し、エ
チルアルコールを分散媒としてボールミルで２０ｈ混合
して、乾燥し、空気中で７３０℃の温度で２ｈ熱処理し
た。このようにして酸化ニッケルNiO を不純物として含
む酸化スズSnO2の粉体を得た。得られた粉体をボールミ
ルで粉砕したのち、塩化白金酸H2PtCl6 水溶液を加え、
混練して乾燥し、白金Ptを２％含有する粉体を得た。こ
の粉体を６００℃で３ｈ熱処理し、塩化白金酸H2PtCl6
を分解した。このようにして酸化ニッケルNiOと白金Pt
を触媒として含む酸化スズSnO2粉体を得た。得られた粉
体をボールミルで粉砕し、エチルシリケート，エチルセ
ルロース，カルビトール等を適量加え、混練して酸化燃
焼層用のペーストを得た。得られた酸化燃焼層用のペー
ストを所定のパターンにより２０μｍ厚さにスクリーン
印刷し、１２０℃で２ｈ乾燥し，第二の酸化燃焼層の成
型層を得た。The stannic acid powder was dried, nickel oxide NiO was added to the resulting stannic acid powder in a proportion of 500 ppm, and the mixture was mixed in a ball mill for 20 hours with ethyl alcohol as a dispersion medium and dried, and then 730 in air. Heat treatment was performed for 2 hours at a temperature of ° C. In this way, tin oxide SnO 2 powder containing nickel oxide NiO 2 as an impurity was obtained. After crushing the obtained powder with a ball mill, chloroplatinic acid H 2 PtCl 6 aqueous solution was added,
After kneading and drying, a powder containing 2% platinum Pt was obtained. This powder was heat-treated at 600 ° C for 3 hours, and chloroplatinic acid H 2 PtCl 6 was added.
Disassembled. In this way nickel oxide NiO and platinum Pt
SnO 2 powder containing SnO 2 as a catalyst was obtained. The obtained powder was pulverized with a ball mill, an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added and kneaded to obtain a paste for an oxidation combustion layer. The obtained paste for oxidative combustion layer was screen-printed in a predetermined pattern to a thickness of 20 μm and dried at 120 ° C. for 2 hours to obtain a second molded layer of oxidative combustion layer.
【００１４】スズ酸粉体を乾燥し、乾燥空気中において
７３０℃の温度で２ｈ熱処理し、得られた酸化スズ粉体
にエチルシリケート，エチルセルロース，カルビトール
等を適量加え混練して感ガス層用のペーストを得た。得
られたペーストを所定のパターンにより５０μｍ厚さに
スクリーン印刷し、１２０℃で２ｈ乾燥して感ガス層の
成型層を得た。For the gas sensitive layer, the stannic acid powder is dried and heat-treated in a dry air at a temperature of 730 ° C. for 2 hours, and the obtained tin oxide powder is kneaded by adding an appropriate amount of ethyl silicate, ethyl cellulose, carbitol and the like. Got the paste. The obtained paste was screen-printed with a predetermined pattern to a thickness of 50 μm and dried at 120 ° C. for 2 hours to obtain a gas-sensitive layer.
【００１５】前記の酸化燃焼層用のペーストを所定のパ
ターンにより２０μｍ厚さにスクリーン印刷し、１２０
℃で２ｈ乾燥して第一の酸化燃焼層の成型層を得た。第
二の酸化燃焼層と感ガス層と第一の酸化燃焼層の三層か
らなる成型層を６３０℃の温度で３ｈ同時に焼成して第
一の酸化燃焼層３Ｘ、感ガス層４、第二の酸化燃焼層３
Ｙを形成した。The paste for the oxidative combustion layer is screen-printed in a predetermined pattern to a thickness of 20 μm, and 120
It was dried at 0 ° C. for 2 hours to obtain a molded layer of the first oxidative combustion layer. A molding layer composed of three layers of a second oxidative combustion layer, a gas-sensitive layer, and a first oxidative combustion layer was simultaneously fired at a temperature of 630 ° C. for 3 hours to form a first oxidative combustion layer 3X, a gas-sensitive layer 4, and a second layer. Oxidized combustion layer 3
Y was formed.
【００１６】続いて電極２，２Ａにそれぞれ白金リード
線７，９を接続して厚膜型ガスセンサを得た。それぞれ
のリード線を警報器の回路に接続した。上述の方法で作
成された第一と第二の酸化燃焼層は酸化ニッケルNiO の
結晶により白金Pt結晶が微細に分散されるとともに結晶
成長が抑止され、干渉ガスの燃焼と感ガス層への酸素供
給用として機能する活性と安定性に優れる触媒層とな
る。Subsequently, platinum lead wires 7 and 9 were respectively connected to the electrodes 2 and 2A to obtain a thick film type gas sensor. Each lead wire was connected to the alarm circuit. In the first and second oxidative combustion layers prepared by the above method, platinum Pt crystals are finely dispersed by nickel oxide NiO crystals and crystal growth is suppressed, and combustion of interfering gas and oxygen to the gas sensitive layer are suppressed. The catalyst layer functions as a supply and has excellent activity and stability.
【００１７】図３はこの発明の実施例に係る厚膜型ガス
センサにつき抵抗値の経過日数依存性（ア）を従来の厚
膜型ガスセンサの特性（イ）と対比して示す線図であ
る。測定は空気で希釈した０．２％濃度のイソブタンガ
ス中で行った。第一と第二の酸化燃焼層中に酸化ニッケ
ルNiO と白金の触媒を担持した本発明の厚膜型ガスセン
サは抵抗値の安定性が従来の厚膜型ガスセンサより良好
であることがわかる。これは酸化燃焼層の触媒活性が安
定であることによる。エージング期間も短縮されてい
る。これは酸化燃焼層の触媒活性が大きいためである。FIG. 3 is a diagram showing the dependency of the resistance value on the elapsed days (a) in the thick film gas sensor according to the embodiment of the present invention in comparison with the characteristic (a) of the conventional thick film gas sensor. The measurement was carried out in 0.2% isobutane gas diluted with air. It can be seen that the stability of the resistance of the thick film gas sensor of the present invention in which the catalysts of nickel oxide NiO and platinum are carried in the first and second oxidation combustion layers is better than that of the conventional thick film gas sensor. This is because the catalytic activity of the oxidation combustion layer is stable. The aging period has also been shortened. This is because the catalytic activity of the oxidation combustion layer is large.
【００１８】図４はこの発明の実施例に係る厚膜型ガス
センサにつき抵抗値の電圧依存性（ウ）を従来の厚膜型
ガスセンサの特性（エ）と対比して示す線図である。厚
膜型ガスセンサの抵抗値は空気中のものである。本発明
の厚膜型ガスセンサは従来のものに比し、抵抗値の電圧
依存性が少ないことがわかる。なお酸化ニッケルNiO の
添加量は１００ｐｐｍないし５０００ｐｐｍの範囲が適
当であり、白金Ptの添加量は１ないし５重量％が適当で
ある。FIG. 4 is a diagram showing the voltage dependence (c) of the resistance value of the thick film gas sensor according to the embodiment of the present invention in comparison with the characteristic (d) of the conventional thick film gas sensor. The resistance value of the thick film gas sensor is that in air. It can be seen that the thick film gas sensor of the present invention has less voltage dependency of resistance value than the conventional one. The addition amount of nickel oxide NiO is suitably in the range of 100 ppm to 5000 ppm, and the addition amount of platinum Pt is suitably 1 to 5% by weight.
【００１９】さらに金属酸化物半導体である酸化スズSn
O2に加える酸化物は酸化ニッケルNiO に替えて酸化第二
鉄Fe2O3 ，酸化アルミニウムAl2O3 ，酸化クロムCr2O3
等を用いることができる。またｎ型金属酸化物半導体は
酸化スズSnO2の他酸化亜鉛等を用いることもできる。 実施例２ 酸化スズ粉体を乾燥し、得られた酸化スズ粉体に酸化ニ
ッケルNiO を５００ｐｐｍの割合で添加し、エチルアル
コールを分散媒としてボールミルで２０ｈ混合し、乾燥
した。得られた粉体に塩化白金酸H2PtCl6 水溶液を加
え、混練して乾燥し、白金Ptを２％の割合で含有する酸
化スズSnO2の粉体を得た。この粉体を７３０℃で２ｈ熱
処理し、塩化白金酸H2PtCl6 を分解した。このようにし
て酸化ニッケルNiO と白金Ptを含む酸化スズSnO2の粉体
を得た。得られた粉体をボールミルで粉砕し、エチルシ
リケート，エチルセルロース，カルビトール等を適量加
え、混練して酸化燃焼層用のペーストを得た他は実施例
１と同様にして厚膜型ガスセンサを作製した。Further, tin oxide Sn which is a metal oxide semiconductor
Oxide added to O 2 was replaced with nickel oxide NiO, ferric oxide Fe 2 O 3 , aluminum oxide Al 2 O 3 , chromium oxide Cr 2 O 3
Etc. can be used. As the n-type metal oxide semiconductor, tin oxide SnO 2 or zinc oxide can be used. Example 2 A tin oxide powder was dried, nickel oxide NiO was added to the obtained tin oxide powder at a ratio of 500 ppm, and the mixture was dried in a ball mill for 20 hours with ethyl alcohol as a dispersion medium and dried. A chloroplatinic acid H 2 PtCl 6 aqueous solution was added to the obtained powder, and the mixture was kneaded and dried to obtain a tin oxide SnO 2 powder containing platinum Pt in a proportion of 2%. This powder was heat-treated at 730 ° C. for 2 hours to decompose chloroplatinic acid H 2 PtCl 6 . Thus, tin oxide SnO 2 powder containing nickel oxide NiO and platinum Pt was obtained. The obtained powder was pulverized with a ball mill, and an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added and kneaded to obtain a paste for an oxidative combustion layer, and a thick film type gas sensor was produced in the same manner as in Example 1. did.
【００２０】本方法で厚膜型ガスセンサを調製する場合
は酸化スズSnO2と酸化ニッケルNiOに対して個別に触媒
を担持できる。 実施例３ スズ酸粉体を乾燥し、得られたスズ酸粉体に塩化ニッケ
ルの水溶液を加えて混練し、乾燥し、空気中において７
３０℃の温度で２ｈ熱処理した。このようにして酸化ニ
ッケルNiO を５００ｐｐｍの割合で含む酸化スズSnO2の
粉体を得た。When a thick film type gas sensor is prepared by this method, a catalyst can be individually supported on tin oxide SnO 2 and nickel oxide NiO. Example 3 A stannic acid powder was dried, an aqueous solution of nickel chloride was added to the resulting stannic acid powder, and the mixture was kneaded, dried, and dried in air.
Heat treatment was performed at a temperature of 30 ° C. for 2 hours. In this way, tin oxide SnO 2 powder containing nickel oxide NiO at a ratio of 500 ppm was obtained.
【００２１】得られた粉体をボールミルで粉砕したの
ち、塩化白金酸H2PtCl6 水溶液を加え、混練して乾燥
し、６００℃で３ｈ熱処理し、塩化白金酸H2PtCl6 を分
解した。このようにして酸化ニッケルNiO ５００ｐｐｍ
と白金Pt２％を触媒として含む酸化スズSnO2粉体を得
た。得られた粉体をボールミルで粉砕し、エチルシリケ
ート，エチルセルロース，カルビトール等を適量加え、
混練して酸化燃焼層用のペーストを得た他は実施例１と
同様にして厚膜型ガスセンサを作製した。The obtained powder was pulverized with a ball mill, and then an aqueous solution of chloroplatinic acid H 2 PtCl 6 was added, kneaded and dried, and heat-treated at 600 ° C. for 3 hours to decompose chloroplatinic acid H 2 PtCl 6 . In this way nickel oxide NiO 500ppm
SnO 2 powder containing tin oxide and Pt 2% as a catalyst was obtained. The obtained powder is crushed with a ball mill, and an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. is added,
A thick film type gas sensor was produced in the same manner as in Example 1 except that the paste for the oxidative combustion layer was obtained by kneading.
【００２２】本方法で厚膜型ガスセンサを調製すると、
酸化ニッケルNiO の分散状態が良く、触媒の活性が増大
する。When a thick film type gas sensor is prepared by this method,
Nickel oxide NiO is well dispersed and catalyst activity increases.
【００２３】[0023]
【発明の効果】この発明によれば、厚膜型ガスセンサを
第一の酸化燃焼層と、感ガス層と、第二の酸化燃焼層を
含む三層型とし、酸化燃焼層はｎ型金属酸化物半導体に
酸化ニッケル，酸化鉄，酸化アルミニウム，酸化クロム
の群から選ばれた少なくとも一つと貴金属を触媒として
均一に分散して担持するので、酸化燃焼層から感ガス層
へ酸素を供給する酸化燃焼層の触媒作用が貴金属単独の
場合より増大し、ヒータ電圧の変動により厚膜型ガスセ
ンサの温度が上昇しても厚膜型ガスセンサの抵抗値の変
動は小さく、ヒータ電圧の変動により警報を発すること
のない信頼性に優れる厚膜型ガスセンサが得られる。According to the present invention, the thick film type gas sensor is a three-layer type including a first oxidation combustion layer, a gas sensitive layer and a second oxidation combustion layer, and the oxidation combustion layer is an n-type metal oxide. Since at least one selected from the group consisting of nickel oxide, iron oxide, aluminum oxide and chromium oxide and a noble metal are uniformly dispersed and supported on a semiconductor as a catalyst, the oxidative combustion supplies oxygen from the oxidative combustion layer to the gas-sensitive layer. Even if the catalytic action of the layer is higher than that of the noble metal alone and the temperature of the thick film gas sensor rises due to the fluctuation of the heater voltage, the fluctuation of the resistance value of the thick film gas sensor is small and an alarm is issued by the fluctuation of the heater voltage. It is possible to obtain a thick film type gas sensor having excellent reliability.
【００２４】さらに酸化燃焼層の触媒活性の増大と安定
性により、可燃性ガス中の抵抗値が従来の厚膜型ガスセ
ンサよりも安定であり、エージング期間も短縮された厚
膜型ガスセンサが得られる。Further, due to the increased catalytic activity and stability of the oxidation combustion layer, the resistance value in the combustible gas is more stable than the conventional thick film type gas sensor, and the thick film type gas sensor with shortened aging period can be obtained. .
【図１】この発明の実施例に係る厚膜ガスセンサを示す
平面図FIG. 1 is a plan view showing a thick film gas sensor according to an embodiment of the present invention.
【図２】この発明の実施例に係る厚膜ガスセンサを示す
図１のＡ−Ａ矢視断面図FIG. 2 is a sectional view taken along the line AA of FIG. 1 showing a thick film gas sensor according to an embodiment of the present invention.
【図３】この発明の実施例に係る厚膜型ガスセンサにつ
き抵抗値の経過日数依存性（ア）を従来の厚膜型ガスセ
ンサの特性（イ）と対比して示す線図FIG. 3 is a diagram showing the dependency of the resistance value on the number of days elapsed (a) in the thick film gas sensor according to the embodiment of the present invention in comparison with the characteristic (a) of the conventional thick film gas sensor.
【図４】この発明の実施例に係る厚膜型ガスセンサにつ
き抵抗値の電圧依存性（ウ）を従来の厚膜型ガスセンサ
の特性（エ）と対比して示す線図FIG. 4 is a diagram showing the voltage dependence (c) of the resistance value of the thick film gas sensor according to the embodiment of the present invention in comparison with the characteristic (d) of the conventional thick film gas sensor.
【図５】従来の厚膜型ガスセンサを示す平面図FIG. 5 is a plan view showing a conventional thick film gas sensor.
【図６】従来の厚膜型ガスセンサを示す図５のＢ−Ｂ矢
視断面図6 is a sectional view taken along the line BB in FIG. 5 showing a conventional thick film gas sensor.
１ 基板 ２ 電極 ２Ａ 電極 ３Ａ 第一の酸化燃焼層 ３Ｂ 第二の酸化燃焼層 ３Ｘ 第一の酸化燃焼層 ３Ｙ 第二の酸化燃焼層 ４ 感ガス層 ７ リード線 ８ ヒータ ９ リード線 1 substrate 2 electrode 2A electrode 3A first oxidative combustion layer 3B second oxidative combustion layer 3X first oxidative combustion layer 3Y second oxidative combustion layer 4 gas sensitive layer 7 lead wire 8 heater 9 lead wire
Claims (5)
てガスの有無を検出する厚膜型ガスセンサであって、 （１）基板と、 （２）一対の電極と、 （３）第一の酸化燃焼層と、 （４）感ガス層と、 （５）第二の酸化燃焼層と、 （６）ヒータを包含し、 基板はガスセンサの支持体であり、 一対の電極は基板上に離間して直接的に被着され、 第二の酸化燃焼層は基板と一対の電極上に選択的に積層
され、 感ガス層は第二の酸化燃焼層と一対の電極上に選択的に
積層され、 第一の酸化燃焼層は感ガス層の全部を被覆して積層さ
れ、 第一の酸化燃焼層はｎ型金属酸化物半導体からなる担体
に酸化ニッケル，酸化鉄，酸化アルミニウム，酸化クロ
ムの群から選ばれた少なくとも一つと貴金属を触媒とし
て均一に担持してなり、 第二の酸化燃焼層はｎ型金属酸化物半導体からなる担体
に酸化ニッケル，酸化鉄，酸化アルミニウム，酸化クロ
ムの群から選ばれた少なくとも一つと貴金属を触媒とし
て担持してなり、 感ガス層はｎ型金属酸化物半導体からなり、 ヒータは前記基板上に積層されて厚膜型ガスセンサを所
定の温度に加熱するものであることを特徴とする厚膜型
ガスセンサ。1. A thick film gas sensor for detecting the presence or absence of gas by utilizing a change in resistance of a metal oxide semiconductor, comprising: (1) a substrate, (2) a pair of electrodes, and (3) It includes one oxidative combustion layer, (4) gas sensitive layer, (5) second oxidative combustion layer, and (6) heater, the substrate is a support for the gas sensor, and the pair of electrodes is on the substrate. Directly spaced apart, the second oxidation combustion layer is selectively laminated on the substrate and the pair of electrodes, and the gas sensitive layer is selectively laminated on the second oxidation combustion layer and the pair of electrodes. The first oxidative combustion layer is laminated so as to cover the entire gas-sensitive layer, and the first oxidative combustion layer is formed of a nickel oxide, iron oxide, aluminum oxide, and chromium oxide support on an n-type metal oxide semiconductor. At least one selected from the group and a precious metal are uniformly supported as a catalyst, and the second oxidation combustion layer Is a carrier composed of an n-type metal oxide semiconductor and at least one selected from the group consisting of nickel oxide, iron oxide, aluminum oxide and chromium oxide and a noble metal are supported as a catalyst, and the gas sensitive layer is an n-type metal oxide semiconductor. The thick film gas sensor is characterized in that the heater is laminated on the substrate to heat the thick film gas sensor to a predetermined temperature.
て、酸化ニッケル，酸化鉄，酸化アルミニウム，酸化ク
ロムの群から選ばれた少なくとも一つの担持量は１００
ないし５０００ｐｐｍの範囲にあることを特徴とする厚
膜型ガスセンサ。2. The thick film type gas sensor according to claim 1, wherein at least one supported amount of nickel oxide, iron oxide, aluminum oxide and chromium oxide is 100.
To 5000 ppm, a thick film type gas sensor.
て、貴金属の担持量は１ないし５重量％の範囲にあるこ
とを特徴とする厚膜型ガスセンサ。3. The thick-film gas sensor according to claim 1, wherein the amount of the noble metal carried is in the range of 1 to 5% by weight.
て、第一の酸化燃焼層または第二の酸化燃焼層は、ｎ型
金属酸化物半導体に酸化ニッケル，酸化鉄，酸化アルミ
ニウム，酸化クロムの群から選ばれた少なくとも一つを
所定の割合で混合し熱処理したあと、貴金属を担持して
なることを特徴とする厚膜型ガスセンサ。4. The thick film gas sensor according to claim 1, wherein the first oxidative combustion layer or the second oxidative combustion layer is an n-type metal oxide semiconductor made of nickel oxide, iron oxide, aluminum oxide or chromium oxide. A thick film type gas sensor, comprising at least one selected from the group 1) mixed at a predetermined ratio and heat-treated, and then carrying a noble metal.
て、ｎ型金属酸化物半導体は酸化スズであることを特徴
とする厚膜型ガスセンサ。5. The thick film gas sensor according to claim 1, wherein the n-type metal oxide semiconductor is tin oxide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00179494A JP3191544B2 (en) | 1994-01-13 | 1994-01-13 | Thick film type gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00179494A JP3191544B2 (en) | 1994-01-13 | 1994-01-13 | Thick film type gas sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07209235A true JPH07209235A (en) | 1995-08-11 |
| JP3191544B2 JP3191544B2 (en) | 2001-07-23 |
Family
ID=11511482
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00179494A Expired - Fee Related JP3191544B2 (en) | 1994-01-13 | 1994-01-13 | Thick film type gas sensor |
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| Country | Link |
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| JP (1) | JP3191544B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008082770A (en) * | 2006-09-26 | 2008-04-10 | Mikuni Corp | Hydrogen sensor |
| WO2010021777A3 (en) * | 2008-06-03 | 2010-05-27 | University Of Washington | Detection of trace chemicals and method therefor |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11686697B2 (en) | 2020-09-24 | 2023-06-27 | International Business Machines Corporation | Multifunctional heterojunction metal oxide gas sensor |
-
1994
- 1994-01-13 JP JP00179494A patent/JP3191544B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008082770A (en) * | 2006-09-26 | 2008-04-10 | Mikuni Corp | Hydrogen sensor |
| WO2010021777A3 (en) * | 2008-06-03 | 2010-05-27 | University Of Washington | Detection of trace chemicals and method therefor |
| US8673216B2 (en) | 2008-06-03 | 2014-03-18 | The University Of Washington | Detection of trace chemicals and method therefor |
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| Publication number | Publication date |
|---|---|
| JP3191544B2 (en) | 2001-07-23 |
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