JP2002071629A - Layer-built gas sensor element manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a layer-built gas sensor element manufacturing method capable of stably providing a layer-built gas sensor element with high durability wherein the occurrence of warpage of the layer-built gas sensor element itself is extremely reduced and exfoliation, cracks, etc., hardly occur when used. SOLUTION: A slurry is prepared by using an alumina powder, a zirconia powder, a binder resin, and a solvent, to make unbaked sheets for substrates by a doctor blade method. Meanwhile, similar ceramic material powders are used to make unbaked sheets for protection layers having the same amount of binder per unit surface area of the material powders. The sheets for substrates, which become dense after baking and serve as insulating substrates, are layered on one side of an unbaked body for a solid electrolytic body, and the sheets for protection layers, which become porous after baking and serve as insulating protection layers, are layered on the other side thereof. The layer- built body thus obtained is integrally baked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing a laminated gas sensor element. More specifically, a laminated gas sensor element that is particularly resistant to warpage and cracking and that can be stably obtained is a highly durable laminated gas sensor element that hardly peels during use and hardly causes cracks or the like in the obtained laminated gas sensor element. The present invention relates to a method for manufacturing a gas sensor element.

[0002]

2. Description of the Related Art A laminated gas sensor element used for various sensors (oxygen sensor, HC sensor, NOx sensor, etc.) for detecting a specific component in exhaust gas and measuring the concentration thereof in an internal combustion engine or the like is known. In these stacked gas sensor elements, for example, ceramic electrodes are used to cover the detection electrodes that come into contact with the gas to be measured, and to prevent poisoning of Si, P, Pb, and the like, which may deteriorate the performance of the detection electrodes due to these compounds. Porous body may be formed.
On the other hand, in the case of the conventional device, when such a porous layer is provided, the warpage of the device itself cannot be sufficiently prevented, and cracks due to these may be caused.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and provides a highly durable laminated gas sensor element that hardly causes warpage and does not peel or crack. An object of the present invention is to provide a method for manufacturing a laminated gas sensor element to be manufactured.

[0004]

According to a first aspect of the present invention, there is provided a method for manufacturing a laminated gas sensor element, wherein a green body for a substrate and a green body for a porous body are opposed to each other with the green body for a solid electrolyte body interposed therebetween. And forming an unfired laminate, and then integrally firing the unfired laminate. The method for manufacturing a laminated gas sensor element, comprising: The difference in shrinkage during firing with the fired body is 1200 to 1550
It is characterized by being always within ± 3% at ° C.

[0005] A method of manufacturing a multilayer gas sensor element according to a second aspect of the present invention is a method for manufacturing a multilayer gas sensor element, comprising: kneading at least a raw material powder for a substrate and a binder for the substrate;
At least the raw material powder for the porous body and the binder for the porous body are kneaded, and then the unfired body for the porous body obtained by molding is laminated so as to face each other with the unfired body for the solid electrolyte body therebetween. A method for producing a laminated gas sensor element comprising forming an unsintered laminate, and then integrally sintering the unsintered laminate, wherein the raw material powder for a base is contained per unit mass of the unsintered body for a base. A1 (m ² / g) is defined as the value obtained by dividing the surface area of the raw material by the mass of the binder for the substrate, and the surface area of the raw material powder for the porous material contained per unit mass of the green body for the porous material Where A2 (m ² / g) is a value obtained by dividing by the mass of the binder for a porous body, the value X represented by the formula [1] is adjusted to be within ± 0.1. I do.

In the first and second aspects of the present invention, the “green body for solid electrolyte body” is fired to be a solid electrolyte body exhibiting oxygen ion conductivity. This green body for a solid electrolyte body can be obtained by molding a kneaded material (paste or slurry or the like) obtained by kneading a raw material powder for a solid electrolyte body, a binder, a solvent, and the like. When a screen printing method is used in this molding, a film-shaped (less than 50 μm thick) unfired body for a solid electrolyte body can be obtained, and when a doctor blade method is used, a sheet-shaped (50 μm or more) solid electrolyte body can be obtained. A green body can be obtained.

[0007] In the unsintered body for a solid electrolyte body, the main constituent components of layers (such as insulating layers) laminated in contact with the solid electrolyte body are set to 100% by mass of the whole unsintered body for a solid electrolyte body. In this case, 10 to 80% by mass or less (more preferably 3 to 80% by mass)
(0 to 70% by mass or less). Thereby, in the device obtained, the adhesion to the layer laminated in contact with the solid electrolyte body can be greatly improved.

An unsintered body for an electrode serving as a reference electrode and a detection electrode can be formed on one surface or front and back surfaces of the unsintered body for a solid electrolyte body. The green body for an electrode is, for example, P
t, as a main component, Au, Ag, Pd, Ir, Ru, P
h and the like, and a conductive kneaded material in which 25% by mass or less of partially stabilized zirconia having an average particle diameter of less than 1 μm is added (externally compounded) as a sintering binder. Further, a ceramic paste (containing carbon) or a carbon paste for forming a porous layer is applied to the lower side of the reference electrode, and after firing, carbon in the paste disappears to form voids. Oxygen is taken into this space from the outside air, and this atmosphere can be used as a reference oxygen source. The reference electrode is an electrode in contact with the reference gas, an electrode placed under an oxygen atmosphere at a constant pressure formed by an oxygen pump action, or higher than the detection electrode when it comes into contact with a combustible gas component in the gas to be measured. This is an electrode indicating a potential. On the other hand, the other electrode in contact with the gas to be measured is a detection electrode.

The above-mentioned “green body for base” is fired to form a base. The green body for a substrate is a sheet-shaped green body for a substrate, which is obtained by kneading a raw material powder for a base, a binder for a substrate, a solvent, and the like, forming a kneaded product by a doctor blade method, and then drying. Can be obtained. Usually, it is preferable that the thickness of the green body for the substrate is 0.2 mm or more. In the unsintered body for the base, unsintered conductive patterns that are fired to be the heating resistors and the lead portions for the heating resistors can also be formed. In this case, by applying a voltage to the heating resistor of the base obtained after firing, it can be used as a heating source for activating the solid electrolyte body.

It is preferable that the substrate obtained from the green body for a substrate has a function of reinforcing the mechanical strength of the element itself, and can exhibit high insulating properties. In particular, it is preferable that the insulating property at a temperature of 900 ° C. is 100 times or more that of the solid electrolyte body. Further, in the laminated gas sensor element (hereinafter, also simply referred to as “element”) obtained by the production method of the first and second inventions, the base and the solid electrolyte obtained from the unfired solid electrolyte are used. They may be formed in direct contact with each other, or may be formed, for example, with a layer having another function such as a buffer layer that reduces thermal expansion when the base includes a heating resistor.

As the "raw material powder for the substrate", ceramic powders such as alumina, mullite, magnesia-alumina spinel and the like can be used, but it is particularly preferable to mainly use alumina. However, in order to improve the adhesion after firing with other layers, components contained in other layers such as zirconia should be contained in an amount of not more than 30% by mass when the whole raw material powder for the substrate is 100% by mass. Can be. The "binder for the substrate" is not particularly limited, and an acrylic polyvinyl butyral resin, an alcohol stearate, ethyl cellulose, or the like can be appropriately used.
It should be noted that the binder for the base may be one kind of binder,
A binder in which seeds or more are mixed may be used.

The above-mentioned "green body for porous body" is fired to form a porous body. The green body for a porous body is a thin film obtained by kneading a raw material powder for a porous body, a binder for a porous body, a solvent, and the like, by screen printing or the like (multiplying if necessary). It is obtained by molding into a shape and drying. Further, the above kneaded material can be formed into a sheet by a doctor blade method or the like and dried to obtain the kneaded material. still,
A component contained in another layer such as zirconia is contained in an amount of 30% by mass or less when the whole unfired body for a porous body is 100% by mass in order to improve the adhesion after firing with another layer. be able to. The “binder for a porous body” is not particularly limited, and a compound similar to the binder for the base can be appropriately used.

The “raw material powder for a porous body” may be one kind of powder or a powder in which two or more kinds are mixed, and the same ceramic-based powder as the base material powder is used. be able to. Further, as in the third invention, when the total of the balance of the porous material binder and the remainder of the porous material raw material powder excluding the porosity agent is 100% by volume,
The porogen is 30 to 55% by volume (more preferably 35 to 5% by volume).
0% by volume). If the amount of the porogen is less than 30% by volume, it is difficult to obtain sufficient pores after firing, and the gas to be measured tends to hardly reach the detection electrode. 5
If the content exceeds 5% by volume, it is difficult to sufficiently obtain the mechanical strength of the obtained porous body, and the poisoning of the detection electrode by Si, P, Pb, or a compound thereof is sufficiently prevented. It tends to be difficult.

The "porous agent" includes (1) carbon powder, (2) sublimable xanthine derivatives such as theobromine, caffeine and theophylline, (3) xanthopterin, m-aminobenzoic acid, and m-acetamidobenzoic acid. Acid, 4,4′-benzophenone dicarboxylic acid, acetoracene carboxylic acid, α-aminobutyric acid, isonicotinic acid,
Isopanilic acid, isophthalic acid, 5-methylisophthalic acid, o-oxycinnamic acid, 3-oxy-p-toluic acid,
5-oxy-1-naphthoic acid, 5-quinolinecarboxylic acid, 4,5-dioxy-2-anthraquinonecarboxylic acid, 1,3,5-benzenetricarboxylic acid, 3,5-pyridinedicarboxylic acid, (4) pererelin, Phloroglucin trimethyl ether, fluorescein, biphthalidylidene, tetraphenylmethane, thymine, alizarinbury, alloxan, isatin, indigo, oxindigo, indilpine, cantharidin, quinophthalone, 2-
Oxyanthraquinone, 1,5-diaminoanthraquinone, 1,5-dioxyanthraquinone, 1,7-dioxyanthraquinone, aminoanthraquinone, 2,4-dioxyquinoline, acenaphthenequinone, 5-oxyquinoline, 2, 2 ′ -Azonaphthalene, adenine, p-acetotoluid, 8-amino-2-naphthol and the like. These may be used in combination of two or more.

Among these pore-forming agents, it is particularly preferable to use carbon powder as in the fourth invention. The average particle size of the carbon powder is preferably 1 to 15 μm (more preferably 3 to 10 μm). Furthermore,
The carbon powder may be a true spherical powder or an irregular shaped powder. Among them, the use of irregular shaped powder can particularly improve the poisoning durability against Si.

A porous body obtained from such a green body for a porous body is usually formed in direct contact with a solid electrolyte body and a sensing electrode. This porous body has (1) a function of preventing a detection electrode coming into contact with a gas to be measured from being poisoned by Si, P, Pb, or the like, or a compound thereof, and (2) a function of using a stacked gas sensor element. (1) to (3) a function of preventing cracks due to the attachment of water droplets and a function of (3) equilibrating a component gas of the gas to be measured by passing the gas to be measured through the porous body. It has at least one function.

In the first invention, the “shrinkage ratio” is
When the green body for a base and the green body for a porous body reach a predetermined temperature during firing, the degree of shrinkage from the size before the start of firing is expressed as a percentage. That is, the length of each unsintered body before the start of sintering is set to L1, the unsintered bodies are each placed in a furnace, and the temperature is increased by 100 ° C./hour to 1100 ° C., and from this 1100 ° C., a predetermined temperature of 60 ° C./hour (1250
C., 1400.degree. C., 1475.degree. C. and 1550.degree. C.), hold at this predetermined temperature for 1 hour, and then cool the furnace and take out the base and the porous body from the furnace to have a length of L2. The ratio S (%) represented by the following equation [2] is defined as the shrinkage ratio. S (%) = (L1−L2) / L1 × 100 [2]

The difference in shrinkage between the unsintered body for the base and the unsintered body for the porous body opposed to each other across the solid electrolyte body is always within ± 3% between 1200 and 1550 ° C. By doing so, the difference in shrinkage ratio is small in the entire firing temperature range, and the occurrence of warpage can be greatly suppressed. By always keeping the difference in shrinkage within ± 3%, the rate of warpage (the number of warpages / manufacturing number) can be reduced to 6% or less, and further to 1% or less.

In the second invention, the "value X" is ±
By making the difference within 0.1 (more preferably within ± 0.07, and still more preferably within ± 0.04), the difference in shrinkage rate becomes small as in the first invention, and the occurrence of warpage is largely suppressed. be able to. By keeping X within ± 0.1, the warpage occurrence rate can be reduced to 6% or less, and further to 1% or less. That is, by making the amount of the binder for the substrate relative to the surface area of the raw material powder for the substrate close to the amount of the binder for the porous body relative to the surface area of the raw material powder for the porous body, the difference in the shrinkage ratio during firing can be reduced. it can. It is particularly preferable that the first and second aspects of the invention are simultaneously satisfied.

In order to achieve the conditions of the first invention and the second invention, for example, the types of the components contained in the raw material powders for the base material or the porous body and the proportions thereof are brought closer to each other. can do. Furthermore, it can be achieved by making the average particle size of each raw material powder closer.

Incidentally, the warpage referred to in the present specification refers to FIG.
As shown in FIG. 2, the height including the warpage of the front part of the element (the part whose upper part is covered by the porous body) is d1, and the actual height of the front part of the element is d2 as shown in FIG. 2 (ii). D1-d2 in this case is 200 μm or more. This d
If 1-d2 exceeds 200 μm, cracks and cracks tend to occur during use.

When the unsintered laminate in which the unsintered body for the base, the unsintered body for the solid electrolyte body, and the unsintered body for the porous layer are laminated as described above,
The heating rate, firing temperature and firing time are not particularly limited, but the heating rate is 200 ° C./hour (more preferably 1 ° C./hour).
(00 ° C./hour). The firing temperature is 14
00 to 1550 ° C (more preferably 1450 to 1520
C). Further, the time for maintaining the temperature is preferably set to 1 to 2 hours.

According to the production methods of the first and second inventions, the thickness of the solid electrolyte body in the laminating direction is usually 30 to 13
0 μm (more preferably 50 to 100 μm), the thickness of the base in which the heating resistor is embedded in the stacking direction is 900 to 1100 μm, and the thickness of the porous body in the stacking direction is 150 to 400 μm ( More preferably, 200 to 3
00 μm). In particular, the substrate and the porous body are preferably thicker in the stacking direction than the solid electrolyte body. After satisfying the thicknesses in the respective stacking directions, the base and the porous body are thicker in the stacking direction of the solid electrolyte body. 1.15 to 13.3 times (more preferably 4.0 to 8.
0).

Further, the relative density of the substrate is preferably at least 96% (more preferably at least 98%, usually at most 99.9%). The relative density of the porous body is 40 to 85.
% (More preferably 50 to 80%), and the porosity is 15 to 65% (more preferably 20 to 50%).
%). If the relative density of the substrate is less than 96%, the resulting device may not have sufficient mechanical strength. On the other hand, if the relative density of the porous body is less than 40% or the porosity exceeds 65%, it is difficult to obtain a sufficient poisoning prevention effect, and if the relative density is more than 85% or the porosity is less than 15%, the porous body is coated. It takes time for the measurement gas to reach the detection electrode surface, which tends to make accurate measurement difficult.

The relative density is obtained by calculating the composition from elemental analysis in advance, setting the theoretical density calculated from the composition to ρ1, and the actual density measured by the Archimedes method to ρ2.
This is a ratio D (%) calculated by the following equation [2]. D (%) = {ρ2 / ρ1} × 100 [2] The porosity is the apparent volume (including the pore volume) V of the porous body, the mass m1 in the air, and the mass just immersed in water. It is a ratio P (%) calculated by the following formula [3] using m2 and a mass m3 (by vacuum defoaming, boiling defoaming, or the like) in which water is sufficiently contained in pores after immersion in water. . P (%) = {(m3-m1) / (m3-m2)} × 100 [3]

The substrate and the porous body preferably contain at least alumina of alumina and zirconia. Among them, the substrate preferably contains 70% by volume or more (more preferably 80% by volume or more) of alumina when the whole is 100% by volume, and the whole of the porous body is 100% by mass. In this case, it is preferable that alumina is contained in an amount of 56% by mass or more (more preferably 60% by mass or more, further preferably 70% by mass or more).
Furthermore, it is particularly preferable that the substrate be constituted by substantially the same composition.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to an embodiment and FIG. [1] Manufacture of Element In the following manufacturing method, each pattern is printed on a sheet having the size of one element and the layers are stacked for easy understanding. However, in an actual process, a required number of prints are applied to a green sheet having a size capable of manufacturing ten elements, and after laminating, a green laminate having an element shape is cut out and degreased. Then, firing was performed to manufacture an element. Further, in one manufacturing process, 300 elements are manufactured at a time.

(1) Preparation of Unsintered Sheet for Substrate Alumina powder (purity 99.99%
As described above, the average particle size is 0.3 μm, and the specific surface area is 4.8 m ² / g.
Was mixed with 115 g of butyral resin and 47.5 g of dibutyl phthalate, which are binders for the base, and a mixed solvent consisting of toluene and methyl ethyl ketone to form a slurry. And a green body for the second substrate was produced.
The unfired body for the first substrate has a thickness of 0.4 mm and a length of 5 cm, and after firing, becomes the first substrate 11a. The unfired body for the second substrate has a thickness of 0.25 mm and a length of 5 cm, and after firing, becomes the second substrate 11b. In addition, A1 of the unfired body for the first base and the unfired body for the second base is 41.74 m ² / g.

(2) Formation of heater pattern Alumina powder (purity 99.99% or more, average particle size 0.3
μm) A conductive layer paste containing 4 parts of platinum powder and 100 parts of platinum powder was mixed with the green body for the first base (after firing, the first base 11
a) a heating element pattern (after firing, heating element 12
1) is printed and dried, and then alumina powder (purity 9)
A heater lead pattern (after firing, heater lead 122) is printed and dried with a conductive layer paste containing 2 parts by mass of 9.9% or more and an average particle size of 0.3 μm) and 100 parts of platinum powder. Pattern (after firing, heating resistor 1
2) was formed. Next, a through-hole 1 is provided near the base end of the first unfired body for a base to establish conduction of the heating resistor 12.
11a was formed, and a heating resistor terminal pattern (after firing, heating resistor terminal 19a) was printed and dried at a position corresponding to the through hole 111a on the back surface. Thereafter, the unfired body for the second substrate (after firing, the upper half of the substrate) was laminated from above the heater pattern and pressure-bonded.

(3) Formation of Buffer Layer Pattern A buffer layer paste containing 80 parts of alumina and 20 parts of zirconia mixed on the green body for the second substrate of the ceramic laminate prepared in (2) was prepared. Layer pattern (after firing,
The buffer layer 13) was printed and dried to a thickness of 40 ± 10μ. (4) Formation of Reference Electrode Pattern On the buffer layer pattern formed in (3), using a conductive layer paste containing 87 mass% of platinum powder and 13 mass% of coprecipitated yttria-containing zirconia powder, a reference electrode portion was formed. Printing and drying a reference electrode pattern (after firing, reference electrode 14a) composed of a pattern (after firing, reference electrode portion 141a) and a reference electrode lead portion pattern (after firing, reference electrode portion 142a) to a thickness of 20 μm ± 10. I let it.

(5) Formation of solid electrolyte pattern Zirconia powder (purity 99.9% or more, average particle size 0.3
μm) 50 parts and alumina powder (purity 99.99% or more,
50 parts with an average particle size of 0.3 μm) was mixed with an appropriate amount of acetone together with 0.5 part of a dispersing agent, and 3 parts were mixed with a resin pot.
The mixture was kneaded for a time to prepare a slurry. On the other hand, the binder 20
A binder solution was prepared by mixing a mixture of 33.3 parts of butyl carbitol, 0.8 part of dibutyl phthalate, and 0.8 part of dibutyl phthalate in an appropriate amount of acetone. Add this binder solution to the slurry,
The acetone was evaporated while kneading to prepare a solid electrolyte paste. The viscosity of the paste was adjusted by further adding butyl carbitol to the prepared paste.
This solid electrolyte body paste was printed and dried in a length direction of 7.0 mm and a thickness of 45 ± 10 μm so as to cover the reference electrode portion pattern to form a solid electrolyte body pattern (solid electrolyte body 15 after firing). .

(6) Formation of insulating layer pattern The unfired substrate prepared in (1) was treated with butyl carbitol 50
A part and a required amount of acetone were added and dissolved, and after mixing for 4 hours, the acetone was evaporated to prepare an insulating layer paste. This paste for the insulating layer was applied to the portion on the buffer layer pattern where the solid electrolyte pattern was not printed.
Printing and drying were performed at a thickness of 5 ± 10 μm to form an insulating layer pattern (after firing, the insulating layer 16). However, the portion corresponding to the through hole 161 is not printed.

(7) Forming the sensing electrode pattern On the solid electrolyte pattern and the insulating layer pattern formed in (5) and (6), using the conductive layer paste prepared in (4), the sensing electrode portion is formed. A detection electrode pattern (after firing, the detection electrode 14b) composed of a pattern (after firing, the detection electrode portion 141b) and a detection electrode lead portion pattern (after firing, the detection electrode portion 142b) is printed and dried to a thickness of 20 ± 10 μm. I let it.

(8) Preparation and lamination of unsintered body for reinforcing layer Using a slurry prepared with the same raw materials and mixing ratio as in (1), the unsintered body for the first reinforcing layer and the second A green body for a reinforcing layer was produced. The unsintered body for the first reinforcing layer has a thickness of 0.25 mm and a length of 4 cm, becomes the first reinforcing layer 18a after the sintering, and has a through hole 181a formed at the base end. The green body for the second reinforcing layer is
0.4 mm in thickness and 4.0 cm in length.
It becomes the reinforcing layer 18b, and the through hole 181b is provided at the base end.
Are formed. Thereafter, the green body for the first reinforcing layer is laminated so as to cover the electrode lead portion pattern of the detection electrode pattern formed in (7), and then the green body for the second reinforcing layer is further laminated with the first reinforcing layer. It was laminated on a green body for use.

(9) Formation of electrode terminal pattern Using the conductive paste prepared in (2), an electrode terminal pattern for inputting and outputting signals to and from each of the reference electrode and the detection electrode (after firing, the electrode terminal 19b ), Through hole 18
Printing and drying were performed at the position corresponding to 1b.

(10) Preparation and Lamination of Unfired Body for Porous Body As in (1), alumina powder (purity of 99.99% or more, average particle diameter of 0.3 μm, 780 g of a surface area of 4.8 m ² / g) and 220 g of carbon powder (spherical particles, average particle size of 5 μm) as a pore-forming agent;
A dispersant and a mixed solvent of toluene and methyl ethyl ketone are mixed, and then 97 g of butyral resin as a binder for a porous body and 47 g of dibutyl phthalate are mixed.
And further mixed to obtain a slurry. Thereafter, a green sheet having a thickness of 250 μm was prepared by a doctor blade method, and formed into a green body for a porous body having a length of 10 mm and a width of 4 mm. A2 of the unfired body for a porous body is 4
2.09 m ² / g. Then, the obtained unsintered body for a porous body (sintered, porous body 17) was laminated so as to cover the detection electrode portion pattern formed in (7).

A1 of the green body for the first base and the green body for the second base obtained in (1) is 41.74 m ² / g, and the green body for the porous body obtained in (10) is A2 of the body is 4
2.09 m ² / g. Therefore, X represented by the above formula [1] is -0.008, which is within ± 0.1.

(11) Degreasing and firing The laminate obtained in (1) to (10) was heated from room temperature to 420 ° C. at a rate of 10 ° C./hour in an air atmosphere, and held for 2 hours. A degreasing treatment was performed. Thereafter, in an air atmosphere, the temperature is raised to 1100 ° C. at a rate of 100 ° C. /
The temperature is raised over time, and the temperature is raised to 1520 ° C at a rate of 60 ° C.
The temperature was raised for 1 hour, the temperature was maintained for 1 hour, and calcination was performed. No warpage was observed in the obtained device, and no cracks and cracks were observed.

[2] Production of green body for base and green body for porous body having different shrinkage ratios In the steps (1) to (11) in [1], they are blended in (1) and (10). By changing the amount of the binder, thirteen types of green bodies for bases having different shrinkage rates and seven types of green bodies for porous bodies having different shrinkage rates shown in Table 1 were produced.

[0040]

[Table 1]

The shrinkage rate of these unsintered bodies for a substrate and unsintered bodies for a porous body at 1200 to 1550 ° C. can be determined at 1100 ° C. and 1250 ° C. using the equation (2) under the above-mentioned conditions.
° C, 1400 ° C, 1475 ° C, and 1550 ° C.

[3] Preparation of unfired laminate The unfired body for each substrate and the unfired body for a porous body shown in Table 1 and obtained in [2] were combined with each other as shown in Table 2 in [1]. Lamination was performed in the same manner to obtain a green laminate. The maximum value of the difference in the shrinkage rate at each temperature of the unsintered laminated body of the combination of Experimental Examples 1 to 13 was calculated from the value obtained in [2] and is also shown in Table 2. Further, each A1 of the green body for the base and each A2 of the green body for each porous body were calculated, and are also shown in Table 2. Further, X based on the combination of the green body for the base and the green body for the porous body in Experimental Examples 1 to 13 was also calculated, and is also shown in Table 2.

[0043]

[Table 2]

[4] Firing and Evaluation The unfired laminate obtained in [3] was fired in the same manner as in [11] of [1] to obtain a laminated gas sensor element. 300 elements of each of the obtained Experimental Examples 1 to 13 were immersed in a red ink dissolved in water and then dried, and a crack or a crack generated in the element was observed by a remaining red portion. . The results are shown in Table 2.

From the results shown in Table 2, cracks and cracks were observed in all of the devices of Experimental Examples 1 to 9 in which the difference in shrinkage ratio exceeded ± 3%. In contrast, the difference in shrinkage is ± 3%
Cracks and cracks were not observed at all in the devices of Experimental Examples 10 to 13 which were within. In other words, it can be seen that when manufacturing the device, by adjusting the amount of the binder so as to fall within the range of the first invention or the second invention, it is possible to obtain the device with almost no cracks and cracks.

The device of the present invention generally has a length of 32.
From about 10 mm from the rear end side of the porous body in FIG. 1 (the rear end is one end where the porous body is not formed in the length direction) to the rear end of the element. It is used by being fixed to a fixing device disposed therein. Therefore, it is not exposed to the gas to be measured, and warping and cracking hardly occur during use.

[0047]

According to the first and second aspects of the present invention, it is possible to stably obtain a laminated gas sensor element which hardly causes warping or cracking even when a porous body is provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an element obtained by a manufacturing method of the present invention.

FIG. 2 (i) is a schematic diagram illustrating d1 used for determining the warpage of an element. (Ii) is a schematic diagram for explaining d2 used for determining the warpage of the element.

[Explanation of symbols]

1; gas sensor element, 11a; first base, 11b; second
Substrate, 111a; Through hole, 12; Heating resistor, 1
Reference numeral 14b; Detection electrode, 15; Solid electrolyte layer, 16; Insulating layer, 17; Porous body, 18a; 18b second reinforcing layer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomohiro Mabuchi 14-18, Takatsuji-cho, Mizuho-ku, Nagoya-shi Inside Japan Special Ceramics Co., Ltd. (72) Kunio Yanagi 14-18 Takatsuji-cho, Mizuho-ku, Nagoya City Japan Special Ceramic (72) Inventor Hiroyuki Hayashi 14-18 Takatsuji-cho, Mizuho-ku, Nagoya Japan F-term (reference) 2G004 BB04 BJ03 BM07

Claims (4)

[Claims] An unsintered body for a substrate and an unsintered body for a porous body are laminated so as to face each other across the unsintered body for a solid electrolyte body to form an unsintered laminate. A method for manufacturing a laminated gas sensor element, in which an unfired laminate is integrally fired, wherein a difference in shrinkage ratio between the unfired body for a base and the unfired body for a porous body during firing is 1200 to 1550 ° C. A method for manufacturing a laminated gas sensor element, wherein the value is always within ± 3%. 2. Kneading at least a raw material powder for a substrate and a binder for a substrate, and then kneading the green body for a substrate obtained by molding, and at least a raw material powder for a porous material and a binder for a porous material, and then forming The unsintered body for a porous body obtained in this way is laminated so as to face each other with the unsintered body for a solid electrolyte body therebetween to form an unsintered laminate, and then the unsintered laminate is integrally fired. Wherein the surface area of the base material powder contained per unit mass of the base green body is divided by the mass of the base binder to obtain a value A1 (m ² / m ² ). g), while
When the value obtained by dividing the surface area of the raw material powder for a porous body contained per unit mass of the green body for a porous body by the mass of the binder for a porous body is A2 (m ² / g), Wherein the value X represented by the following formula [1] is adjusted within ± 0.1. X = (A1-A2) / A1 [1] 3. The raw material powder for a porous body contains a porogen, and the total of the remainder of the raw material powder for a porous body excluding the porogen and the binder for the porous body is 100% by volume. 3. The method according to claim 1, wherein the porogen is 30 to 55% by volume. 4. 4. The method according to claim 3, wherein the porosifying agent is carbon powder.