JPS59100853A - Manufacture of oxygen sensor - Google Patents

Abstract

PURPOSE:To prevent generation of strain and cracking of a green sheet to obtain a sensor of small variance by holding a ceramic powder paste layer between two green sheets provided with an electrode layer, pressing the layer into contact with the sheets and sintering them to make the paste layer as a porous oxygen partial pressure reference chamber. CONSTITUTION:The electrodes 2, 3; 4, 5 are printed respectively on both surfaces of the green sheets 11, 12 containing resin and a solid electrolyte ceramic powder such as ZrO2 stabilized by V2O5. The paste consisting of ZrO2 powder, resin and flux is printed covering the electrode 4 of one of the sheet 12, and then dried to form the porous layer 13. Next the sheet 11 is piled on the sheet 12 to make the surface of the layer 13 contact with the side of the electrode 3, heated and press-joined. The oxygen sensor is obtained by the sintering in air at about 1,500 deg.C. The layer 13 is obtained as a porous layer by increasing resin and decreasing ZrO2 powder of the layer 13. Outer atmospheric air is flowed into pores of the layer 13 to obtain the reference chamber. Thereby, occurrence of cracking in the sheets 11, 12, volume variance of the reference chamber as in the case of providing hollow reference chamber are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of manufacturing an oxygen sensor having an oxygen partial pressure reference chamber sealed with an oxygen ion-conducting solid electrolyte ceramic member.

[Prior art]

The basic principle of the oxygen centimeter currently in practical use is to expose one side of polarized electrodes sandwiched between oxygen ion conductive solid electrolyte members to the gas to be measured and the other to the reference oxygen gas. This is to measure the partial pressure ratio between the oxygen gas inside (hereinafter referred to as the oxygen gas to be measured) and the reference oxygen gas.

That is, when there is an oxygen partial pressure difference between the oxygen gas to be measured and the reference oxygen gas, a voltage proportional to the logarithm of these partial pressure ratios is generated between the electrodes, and by detecting this voltage,
The partial pressure of oxygen gas to be measured can be measured. As the reference oxygen gas, atmospheric air or outside air with a controlled oxygen gas partial pressure is used, and the oxygen gas partial pressure can be easily set to an arbitrary value.

FIG. 1 is a sectional view showing an example of such a conventional oxygen sensor, in which 1 is a solid ts'X member, 2.3.4.5 is an electrode layer, and 6 is an oxygen partial pressure reference chamber.

In FIG. 1, an oxygen ion conductive solid electrolyte member 1
Inside, an oxygen partial pressure reference chamber 6 is provided which is sealed from the solid electrolyte member IK. On both sides of the oxygen partial pressure reference chamber 6, a pair of electrodes 2.6 are arranged with the solid electrolyte member 1 in between.
and a pair of electrodes 4.5 are provided, respectively. That is, electrodes 2.5 are provided on the outer surface of the solid electrolyte member 1, electrodes 2.5 are provided on the inner surface of the solid electrolyte member 1 (on the oxygen partial pressure reference chamber 6 side), and electrodes 6 are provided on the inner surface of the solid electrolyte member 1 (on the oxygen partial pressure reference chamber 6 side). electrodes 4 are provided respectively. - Therefore, when measuring the partial pressure of the oxygen gas to be measured, the oxygen sensor is installed in the outside air, and by passing a current between IIL'fi2.3, the oxygen sensor is placed in the outside air to which the electrode 2 is exposed. of oxygen flows into the oxygen partial pressure reference chamber 6 through the solid electrolyte member 1. When the oxygen partial pressure reaches the zero value, the current flow between the electrodes 2 and 3 is stopped. Then, the oxygen gas stored in the oxygen partial pressure reference chamber 6 in this manner is used as a reference oxygen gas. When a voltage is then applied across the electrodes 4.5, the voltage across the electrodes 4.5 represents the logarithm of the ratio of the partial pressure of oxygen gas in the outside air to which the electrodes 5 are exposed to the partial pressure of the reference oxygen gas. , Therefore, the partial pressure of oxygen gas in the outside air can be measured.

Such a conventional oxygen sensor can easily change the partial pressure of the reference oxygen gas in the oxygen partial pressure reference chamber 6 over a wide range, and can accurately detect the oxygen concentration in the gas to be measured over a wide range. can do.

However, such oxygen senna has the following manufacturing disadvantages, which are obstacles to its practical use.

That is, the solid electrolyte member 1 is formed by molding and sintering ceramic powder, but it is difficult to metalize it and integrally mold it into a shape having a hollow part (oxygen partial pressure reference chamber 6). In this case, the manufacturing method shown in FIG. 2 is adopted. In FIG. 2, reference numerals 7, 8, and 9 indicate holes in the green sheet 10, and portions corresponding to those in FIG. 1 are given the same reference numerals.

In FIG. 2, first, a solid dissolved ceramic powder is mixed with a resin and formed into a plate shape to form a green sheet 7.
A green 7-8 having a hole 10 formed by punching or the like is obtained. Electrodes 2.6 are formed on both sides of the green sheet 7 using metal powder,
Furthermore, electrodes 4.5 are formed on both sides of the green sheet 9. Next, green sheet 7.9 becomes green sheet 8.
The king is pressed and sintered in such a way as to sandwich the two, and the oxygen chamber/-1F- shown in FIG. 1 is completed. The hole 10 of the green sheet 8 forms an oxygen partial pressure reference chamber 6 (FIG. 1).

By the way, in the manufacturing process of such an oxygen senna, in the pressing process of green sheet 7.8.9, they are pressed against a parallel plate, but in this case, the green sheet of green sheet 7.9 Since no pressure is applied to the part of the green sheet 7.9 facing the hole 10, distortion remains in this part, and the green sheet 7.9 cracks frequently during sintering. There was a drawback that there was a significant dispersion in the capacity (Fig. 1), and the production yield of the oxygen cell/cell was significantly reduced.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing an oxygen sensor that eliminates the drawbacks of the prior art described above, prevents the occurrence of distortion during crimping of green sheets, and improves manufacturing yield.

[Summary of the invention]

In order to achieve this objective, the present invention compresses two green sheets provided with electrode layers with a ceramic powder paste layer between them, and then dries the ceramic powder paste layer to form a porous oxygen partial pressure standard. When crimping,
[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is an explanatory diagram showing one embodiment of the method for manufacturing an oxygen sensor according to the present invention, and 11.12 is a green sheet;
15 is a porous layer, and parts corresponding to those in FIG. 1 are given the same reference numerals.

In FIG. 5, a green sheet 110 mainly composed of solid electrolyte ceramic powder and resin is coated with polar layers 2.3 on both sides.
In the same manner, polarization layers 4.5 are printed and formed on both sides of the green sheet 12 so as to face each other. Next, a ceramic powder paste layer is printed on the green sheet 12 so as to cover the entire electrode layer 4, and is dried to form a porous layer 16. Next, the porous layer 13 is sandwiched between the green sheets 12 and 12, and the two are bonded together by thermocompression, and the green seeds 11 and 12 are then sintered to form a solid electrolyte ceramic plate that conducts oxygen ions. form.

The ceramic powder paste layer is dried with a sufficiently large proportion of solvent, and the solvent is removed to form a porous layer 16.
The porous layer 13 containing the formed oxygen senna serves as an oxygen partial pressure reference chamber. Therefore, in the case of Green Sea 7-11.12, since pressure is applied to the Green Sea 11.12 by sandwiching the porous layer 13, no distortion occurs. In addition, polarization 2.5 is green sheet 11.12
After the thermocompression bonding and sintering, printing may be performed.

Next, each example will be specifically explained.

(Example 1) ZrO with a particle size of 2 to 4 μm stabilized by Y20s
2 grains, butyral resin, and trichlorethylene were mixed at a weight ratio of 65Nia:2B to form a slurry. This slurry was formed into a green sheet with a thickness of 0.3 plate by slip casting using a conventional doctor pad.

On both sides of the green sheet 110 formed in this way,
A polarizing layer 2.3 and a polarizing layer 4.5 were formed on both sides of the green sheet 12. These polarization layers were formed as follows. First, Pt powder with a particle size of 0.1 to 0.2 μm and ethyl cellulose n-butylcarpitol acetate were mixed in a weight ratio of 80:3:17 to obtain a Pt paste, which was used as an electrode layer material. This was printed on a mesh screen (Green Sea) 11.12 and dried to form a polarized layer 2.3.4.5.

Next, the porous layer 13 was formed on the surface of the green sheet 120' on the pole layer 4 side so as to completely cover the electrode layer 4 by the method described below. i.e. green sea) 11.
The Zr0z powder used to form No. 12, ethyl cellulose, and n-butylcarpitol acetate were mixed in a weight ratio of 20:2o:60 to form a paste, and the resulting ceramic powder paste was used to A stainless steel mesh screen was used to print on the green sheet 12 so as to cover the entire electrode layer 4.

Next, the printed ceramic powder paste layer was applied to 14 (1
Dry for 15 minutes at 'o.

The porous layer 16 was formed by removing the ruacetate.

In this case, the layer thickness of the porous layer 16 was adjusted to a range of 5 to 100 μm. If the layer thickness is 5 μm or less, a short circuit between the '1 and 3.4 poles will occur in the sintering process described below.
When it was 100 μm or less, a gap was generated between the green 7 and the green 11 and 12 in the thermocompression bonding process described later.

The green sheet 11 is placed on top of the green sheet 12 on which the porous layer 13 is formed, with the porous layer 16 and the -tlE4 layer 6 facing each other, and heated at a temperature of 100 to 120'O and a pressure of 10 to 50 kg. /crl, and the green sheets 11 and 12 were thermocompression bonded under conditions of pressure time of 5 to 15 minutes. In this case, the butyral resin contained in the green sheet vitrified, softened and flowed, and the green sheets 11 and 12 were adhered without any gaps so as to cover the convex portions of the porous layer 13.

The thermocompression bonded green sheet 11.12 is 15 in the air.
Sintered at a temperature of 00'O to complete the oxygen sensor.

I let it happen.

The oxygen sensor obtained as described above contains a large amount of resin (ethyl cellulose) in the ceramic powder paste compared to the green sea (green sea) before sintering. Since the amount of r02 powder is small and the other components are organic substances that decompose and scatter during sintering, the
The green sheet 11.12 is densified, and the porous layer 13 becomes more porous, although the molded body obtained by thermocompression bonding of the green sheet 11.12 undergoes constant sintering shrinkage.

The numerous pores formed in the porous layer of the oxygen sensor obtained in this way serve as the oxygen partial pressure reference chamber.) When the oxygen sensor was used to detect the oxygen gas to be measured, there was no variation in the characteristics. , good sensor characteristics were obtained.

(Example 2) As a ceramic powder paste, particle size 4 μmC) A
120s powder, ethyl cellulose, n-7” methylcarpitol acetate weight ratio, 25:15:6
A mixture of porous layer 13 with a ratio of 0.
I got it. Other steps are the same as in the above implementation-1.

However, excellent results similar to those in Example 1 were obtained.

(Example 3) A different method from Example 1. First, only the electrode layer 3 was formed on the green sheet 11, only the electrode layer 4 was formed on the green sheet 7-112, and as in Example 1, the electrode layer 3 was formed on the green sheet 11. The porous layer 13 was formed on the notebook 12, the green sheets 11.12 were pressed and sintered, and then the polarization layer 2.5 was formed by sputtering Pt in a vacuum chamber. In this implementation row as well, excellent sensor characteristics of the oxygen sensor similar to those in Example 1 were obtained.

〔Effect of the invention〕

As explained above, according to the present invention, although molding distortion may occur in the green sheet, it is possible to
It is possible to prevent cracking of the warp plate and the volume of the oxygen partial pressure reference chamber, and to manufacture an oxygen sensor with good sensor resistance at a high yield of 9. It is possible to eliminate the hole machining process of the green sheet that forms the oxygen partial pressure reference chamber, so there is no need for jigs and tools such as punches. A manufacturing method can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional oxygen sensor, FIG. 2 is an explanatory diagram showing a method for manufacturing the oxygen sensor shown in FIG. 1, and FIG. 6 is an implementation example of the method for manufacturing an oxygen sensor according to the present invention.
It is an explanatory diagram showing u. 2.6.4.5...Electrode layer 11.12...Green sheet 13...Porous no.

Claims (1)

[Claims] A reference oxygen gas having a predetermined partial pressure is stored in an oxygen partial pressure reference chamber sealed by a solid electrolyte ceramic plate, and the voltage is detected between electrodes provided on both sides of the solid electrolyte ceramic plate. In the method for manufacturing an oxygen senna, which measures the partial pressure ratio between the measured oxygen gas and the reference oxygen gas, a first method comprising a solid electrolyte ceramic powder and a resin as main components
, forming and sintering an electrode layer on at least one surface of each of the second green sheets, and forming a ceramic powder paste layer on the first green sheet to cover the electrode layer and drying it. A step of making the ceramic powder paste layer into a porous layer, and a step of forming the first green sheet! The first and second green sheets are compressed and sintered by feeding the polar layer and the porous layer, and the porous layer is sealed, and the pores of the porous layer are filled with the oxygen. A method for manufacturing an oxygen sensor, characterized in that it is a partial pressure reference chamber.