JPH087177B2 - Oxygen sensor element and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an oxygen sensor element for detecting the oxygen concentration of various combustion equipment, particularly for air-fuel ratio control used for purifying exhaust gas from an internal combustion engine. Oxygen sensor element and its manufacturing method.

[Prior art and problems] An oxygen sensor element for air-fuel ratio control comprises a solid electrolyte body having oxygen ion conductivity and a pair of electrodes (reference electrode, measurement electrode) provided on the inner and outer surfaces thereof, and a measurement electrode which comes into contact with exhaust gas. Is generally covered with a porous protective layer to protect the gas from exhaust gas. However, in this type of sensor element, the unburnt component contained in the exhaust gas causes a deviation of the excess air ratio (λ), that is, a so-called λ point shift, and the detection accuracy is deteriorated. Therefore, various studies and proposals have been made.

For example, an oxygen sensor element in which a noble metal catalyst is supported in a protective layer has been proposed (JP-A-53-50888, JP-A-50-50888).
14396, ibid. 54-89686). However, this type of oxygen sensor element has a problem in durability during use.
That is, unburned components (CO, etc.) in the exhaust gas are adsorbed or reacted on the supported catalyst and the catalyst expands in volume, causing the protective tank to break, and in the worst case, the protective layer peels off and the electrode sublimes. To do. Further, when the amount of the supported catalyst is increased, clogging occurs and the response is deteriorated. On the other hand, when the amount is too small, the catalyst is scattered and the effect is lost.

Further, there has been proposed an oxygen sensor element having two protective layers and carrying a catalyst only on the outermost layer (JP-A-53-72686 and JP-A-55-13828). However, in this type of oxygen sensor element, the catalyst supporting layer itself is easily peeled off, and the catalytic action cannot be effectively utilized.

Further, an oxygen sensor element composed of a substance that absorbs and releases oxygen as a protective layer has also been proposed (JP-A-62-62).
245148). However, the fact that the protective layer is easily peeled is similar to the above-described technology, and there is a fear that the durability may be deteriorated.

The present invention solves this problem, that is, it has excellent durability, can effectively use a noble metal catalyst, and can maintain accurate air-fuel ratio control stably for a long time without causing a λ point shift and a decrease in responsiveness. The purpose is to develop an oxygen sensor element. Another object is to develop a manufacturing method that enables easy mass production of such oxygen sensor elements.

[Means for Solving the Problems] The present invention has been made as a result of earnest studies in view of these viewpoints.
Similar to Japanese Patent Application No. 62-311278 previously filed by the same applicant,
The present invention has been completed, and the present invention solves the above problems by the following means.

(1) In an oxygen sensor element that includes a reference electrode on one surface side of a solid electrolyte body and a measurement electrode on the other surface side and detects the oxygen concentration of a gas to be measured, the solid electrolyte body is a base and a spherical shape directly coupled to the base. A projection portion, a measurement electrode is provided at a position including at least the spherical projection portion, the measurement electrode is covered with a porous first protective layer, and the first protection layer is a porous second protective layer. Covered with
At least the second protective layer carries a noble metal catalyst that promotes an oxidation reaction of the gas to be measured, and the first protective layer is made of a metal oxide that is chemically stable to the gas to be measured, An oxygen sensor element in which the protective layer comprises a non-stoichiometric transition metal oxide.

(2) An oxygen sensor element in which the transition metal oxide is titania (other configurations are the same as in (1) above).

(3) Oxygen sensor element in which the amount of the catalyst supported on the second protective layer is 0.02 to 5 mol% (converted to a noble metal) with respect to the material of the second protective layer (other configurations are the same as the above (1)). .

(4) A method for producing an oxygen sensor element for detecting an oxygen concentration of a gas to be measured, comprising a reference electrode on one surface side of the solid electrolyte body and a measurement electrode on the other surface side, the other surface of the base material of the solid electrolyte body Regarding the treatment of the side, at least the following steps: (a) a step of attaching spherical particles made of a solid electrolyte, (b) a step of forming an electrode, (c) a step of spraying a metal oxide component, (d) a noble metal A step of immersing in a salt solution, and (e) coating with a paste-like material containing a non-stoichiometric transition metal oxide component and a noble metal component, followed by firing. Manufacturing method of oxygen sensor element.

(5) A method for manufacturing an oxygen sensor element, wherein in the step (a), the solid electrolyte base material and the spherical particles are simultaneously fired.

(6) A method for manufacturing an oxygen sensor element, wherein in the step (d), the dipping is performed under reduced pressure or pressure.

[Preferable Embodiments] The solid electrolyte body may have various shapes such as a bag shape, a plate shape, or a cylindrical shape as long as the front end is closed and the rear end is opened, and the fixed electrolyte material is stable to, for example, ZrO ₂ . It is advisable to use the agent to which Y ₂ O ₃ , CaO, etc. have been added. Both the reference electrode and the measurement electrode (layered) are made porous, and Pt or 2
It is preferable to use a noble metal such as Pt containing Rh of about 10% or less.

The other surface of the solid electrolyte body (the surface forming the measurement electrode) is a spherical protrusion made of solid electrolyte. This is because the spherical projections are made to penetrate into the measurement electrode and further into the protective layer in a wedge shape so as to firmly and physically bond the solid electrolyte body and the protective layer. Due to the presence of the spherical protrusions, even if an unburned component is adsorbed on or reacted with the catalyst in the protective layer and the volume expands, the protective layer is less likely to be peeled from the solid electrolyte body and the durability of the device is enhanced.

As a reference example, the spherical protrusion is configured to be bonded to the base portion of the solid electrolyte through the measurement electrode and located on the outer layer of the measurement electrode.

It comprises a spherical projection and an aggregate of granulated particles, and the granulated particles may be formed as a single layer or multiple layers on the base surface of the solid electrolyte body. The granulated particles are 40 to 100 μm, preferably 50 to 80
It is good to set it to μm. This is because wedge-shaped irregularities are formed to obtain a strong bond with the protective layer. If the thickness is less than 40 μm, the function as a wedge cannot be fully achieved, and if it exceeds 100 μm, the adhesion of the base material becomes weak. The spherical projections may be distributed so as to leave recesses between the granulated particles. In addition to increasing the bonding force with the protective layer, it can also contribute to increasing the electrode surface area.

The material of the spherical protrusions is preferably the same as that of the base of the solid electrolyte body, but may be any solid electrolyte. For example, the base is ZrO ₂ —Y ₂ O ₃ system, and the spherical projection is ZrO ₂ − (CaO, Mg
O) system, the base is ZrO ₂ —Y ₂ O ₃ system, and the spherical protrusion is the base and Y
ZrO ₂ —Y ₂ O ₃ based materials having different ₂ O ₃ contents may be used.

As described above, the measurement electrode must be covered with the porous first protective layer, and the first protective layer must be covered with the porous second protective layer (configuration (1) above).

The first protective layer is the unburned component (CO
, Etc.) adsorbs or reacts with the measurement electrode (noble metal) to prevent the measurement electrode from expanding in volume and peeling off from the solid electrolyte body. The first protective layer may be made of ceramics such as Al ₂ O ₃ , spinel, BeO, ZrO _{2 and the} like, or a mixture thereof, and it is preferable that the main protective layer is mainly made of penel. Its porosity is about 5-20%, its thickness is 100
˜180 μm, preferably about 150 μm. It is preferable that the thickness of the first protective layer at the tip of the element is larger (for example, 3/2 to 2 times) than the thickness at the rear. This is to suppress the occurrence of the so-called "chemical noise" phenomenon in which the sensor output becomes irregular during low temperature use, and to perform more accurate control even during low temperature use. The axial length of the tip is preferably selected from the range of 1/5 to 1/2 of the axial length from the element tip to the element mounting portion. The material may be made different for the thickened portion.

As the noble metal catalyst which accelerates the oxidation of the uncalcined portion of the gas to be measured carried on the first protective layer, a catalyst mainly composed of platinum (Pt), for example, a catalyst composed of Pt 80 wt% or more is preferable. The supported amount is preferably in the range of 0.01 to 5 wt% with respect to the total amount of the constituent material of the first protective layer. This is because if it is less than 0.01 wt%, there is no effect, and if it exceeds 5 wt%, clogging may occur. However, it is preferably 1 wt% or less under the condition of being exposed to rich exhaust gas. This is because if it exceeds 1 wt%, a large amount of unburned components are adsorbed or reacted with the noble metal catalyst to cause the protective layer to be scratched. This catalyst can be uniformly or non-uniformly dispersed in the entire protective layer, and for example, the content of the noble metal may be increased in the element tip portion where the unburned components of exhaust gas are large. Also, the material of the catalyst may be different in each part.

The second protective layer must be composed of a non-stoichiometric transition metal oxide as described above. This is for preventing the loaded noble metal catalyst of the first protective layer from scattering at the time of use and causing a λ point shift and a decrease in output. Further, the catalytic action peculiar to the transition metal by the second protective layer itself and the action of the supported catalyst further promote the oxidation action of the unburned portion of the exhaust gas, and the non-stoichiometry of the second protective layer itself causes electrons or positive electrons depending on the oxygen amount. This is to prevent the unburned components from being excessively adsorbed on the supported catalyst due to the change in the pores, and to maintain the function of the supported catalyst stably for a long period of time. As the transition metal oxide, any of transition metal oxides of Group 3A to Group 8 can be selected as long as it can exhibit the above-mentioned action, but Group 4A, for example, titanium (Ti), Group 8 and others such as cobalt (Co ) And nickel (Ni) oxides are preferred. In particular, non-stoichiometric titania represented by TiOx (x = 1.8 or more and less than 2, preferably 1.95 or more and less than 2) is preferably used. This is because the above action can be exhibited efficiently and the heat resistance is excellent. The content of the titania (TiOx) is preferably 50 wt% or more, and more preferably 70 wt% or more, based on the total amount of the constituent materials (excluding the supported catalyst) of the second protective layer. In this case, the balance may be other non-stoichiometric transition metal oxide, but may be composed of stoichiometric transition metal oxide or the same ceramic material as the first protective layer. The porosity of the second protective layer is preferably larger than that of the first protective layer. This is to prevent deterioration of the passage of the non-measurement gas and the sensor response. For example, it may be 8% to 15% and may be present as open pores (passage pores). From the same viewpoint, the thickness of the second protective layer may be smaller than that of the first protective layer. For example, it may be 10 μm to 50 μm.

The loading amount of the noble metal catalyst in the second protective layer may be smaller than that in the first layer. This is because the transition metal oxide also has a catalytic action, and by reducing the amount of the metal supported, it is possible to prevent clogging due to the catalyst and to effectively utilize the precious metal. In particular, 0.02 to the total amount of the second protective layer
With a supported amount of ~ 5mol%, the catalytic effect is effectively exhibited,
It is possible to prevent delamination due to volume expansion due to the reaction between the catalyst and the unburned gas. It is preferably 0.1 to 2 mol%. This catalyst may be uniformly or non-uniformly dispersed throughout the second protective layer.

As a reference example, at least a part of the protective layer (specific portion)
Even if is composed of a non-stoichiometric transition metal oxide (in the case of the above means (3) and (4)), that is, when it is not always clearly distinguished into two layers, the constitution is as described above. 2 The same as in the protective layer is preferable. The remaining structure may be similar to that of the above-mentioned first protective layer. The entire protective layer may consist of a non-stoichiometric transition metal oxide. The noble metal catalyst may be present regardless of whether it is in the specific portion or the rest.

Next, preferable aspects and actions will be described with respect to the manufacturing method of the present invention, particularly the treatment step on the other surface side (the side where the measurement electrode is to be formed) of the solid electrolyte substrate.

The solid electrolyte base material is preferably formed by mixing and calcining the raw material powder, pulverizing (2.5 μm or less), then forming secondary particles (20 to 150 μm) by spray drying, and molding into a predetermined shape.

The spherical protrusions may be formed by attaching spherical particles having an average particle size of 50 to 100 μm to the surface of the solid electrolyte substrate and then firing. This is because the wedge-shaped irregularities are left sufficiently even after the electrode deposition treatment in the subsequent step and a strong bond with the first protective layer is obtained.
That is, if the spherical particles after firing are less than 40 μm, the function as a wedge cannot be sufficiently fulfilled, and if they exceed 100 μm, the adhesion to the substrate becomes weak. More preferably, it is 50 to 80 μm. Further, finer particles of 10 μm or less may be mixed to further improve the strength. The solid electrolyte base material and the spherical particles may be subjected to simultaneous firing. This is to increase the bond strength between the two. The firing temperature is preferably 1400-1500 ° C. Alternatively, spherical particles may be formed after the electrodeposition treatment. This is especially effective when the measurement electrode cannot be formed when the spherical particles are first deposited.
This provides reliable protection of the measuring electrode and further enhances the bond with the protective layer.

Electrodes can be formed by usual vapor deposition methods such as electroplating and chemical plating, as well as ordinary vapor deposition methods such as sputtering,
It may be performed by vapor deposition or screen printing.

Examples of the formation of the first protective layer include various methods such as brush application, dipping and spraying of a solution or powder of the material, and plasma spraying is particularly preferable. This is because the thermal spray powders have strong adhesion strength, and the porosity and pore diameter can be set arbitrarily by appropriately changing the conditions.

The catalyst may be supported on the first protective layer by immersion treatment in a precious metal salt solution, followed by drying and firing. The concentration of the solution should be determined from the viewpoint that the catalyst is sufficiently dispersed and does not cause clogging during impregnation. For example, when the catalyst is Pt, a solution in which Pt is sufficiently dispersed is H ₂ PtCl ₆
There is a solution, and its Pt concentration should be 0.01 to 5 g / l. Pt
This is because if the concentration is less than 0.01 g / l, the catalytic action becomes insufficient, and if it exceeds 5 g / l, the pores of the first protective layer are clogged and the sensor response deteriorates. The immersion treatment may be performed while reducing or increasing the pressure. This is because the noble metal-containing salt solution is immersed deep inside the first protective layer, and thus the noble metal catalyst can be uniformly dispersed in the first protective layer. The firing temperature is preferably 400 to 700 ° C.

The formation of the second protective layer must be performed by coating the first protective layer with a paste-like material containing a protective layer material and a noble metal component, and then firing. This is because the formation of the protective layer and the loading of the catalyst are carried out at the same time, so that the catalyst is loaded more firmly, the scattering during use is prevented, and the catalytic action is stably exhibited for a long period of time. In addition, when the paste-like material is used, the binder and the like scatter during firing, and the desired porosity and pore diameter can be easily obtained. The paste is obtained by blending a binder, a solvent and the like as usual. As a coating method, brush application,
It may be dipping or spraying. However, plasma spraying is not suitable. This is because sintering of the protective layer material progresses during the thermal spraying, and the pores cannot be obtained in a desired state (particularly with high porosity). The protective layer material and the supported catalyst may be blended by impregnating the protective layer material powder with a noble metal salt solution. This is to ensure uniform blending. The material for the protective layer may be a transition metal oxide or a compound capable of forming the transition metal oxide by thermal decomposition, such as a hydroxide or a salt. The powder particle size is preferably 2 μm or less. This is because the sinterability is improved and the fixing strength is increased, so that the second protective layer is less likely to peel off during use. It is preferably 0.3 to 1.5 μm. The heat treatment is preferably performed at 700 to 900 ° C. in a non-oxidizing atmosphere.

Examples Examples of the present invention will be described below.

1 to 3 show one embodiment, in each of which 1 is an oxygen sensor element, and this element 1 generally produces an oxygen concentration difference between a reference gas and a measured gas (exhaust gas). Obtained solid electrolyte body 2, a pair of porous electrodes (inner electrodes) 3, (outer electrodes) 4 formed on the inner and outer surfaces of the solid electrolyte body 2, a porous protective layer 5 covering the outer electrode 4, and protection And a noble metal catalyst 6, which is uniformly dispersed and supported on the layer 5. Here, the solid electrolyte body 2 is ZrO ₂ and Y ₂
Becomes the O ₃ from those added, the electrodes 3 and 4 are both Pt electrodes, a noble metal catalyst 6 ... it is made of Pt particles.

The solid electrolyte body 2 comprises a base portion 2a and a spherical protrusion 2b located on the outer surface thereof, and an outer electrode 4 and further a protective layer 5 are formed along the shape of the spherical protrusion 2b. or,
The protective layer 5 is composed of a first protective layer 5a located further inside and directly covering the outer electrode 4, and a second protective layer 5b located further outside and exposed to exhaust gas. Both protective layers 5a and 5b are both Pt
The catalyst 6 is carried. Here, the first protective layer 5a is made of spinel and the second protective layer 5b is made of titania.

In FIG. 1, 7 is a housing, 8 is a caulking ring, 9 is a filler, and 10 is a protective tube.

FIG. 4 shows another embodiment, that is, an example of a plate-shaped oxygen sensor element. Since the other parts are the same as the above-mentioned embodiment, the same components are designated by the same reference numerals and their description is omitted. To do.

Next, a production example of the oxygen sensor element of the present invention will be described. The following steps are sequentially performed.

Step 1: ZrO ₂ of more than 99% purity of 99.9% pure Y ₂ O ₃ with 5 mol%
After adding and mixing, it is calcined at 1300 ° C for 2 hours.

Process 2: Wet 80% of particles in a ball mill with water
Is pulverized to a particle size of 2.5 μm or less.

Step 3: Add a water-soluble binder and spray dry to obtain spherical granulated particles having an average particle size of 70 μm. -(Construction) 3 Step 4: The powder obtained in (Construction) 3 is rubber-pressed, formed into a desired tube (test tube), dried, and ground with a grindstone into a predetermined shape.

Step 5: A slurry to which a water-soluble sodium binder cellulose glycolate and a solvent are added is attached to the granulated particles obtained in (3) on the outer surface.

Step 6: After drying, firing at 1500 ° C. × 2 hrs. Regarding the part corresponding to the detection part, the axial length is 2 mm, the outer diameter is about 5 mmφ,
The inner diameter was about 3 mmφ.

Process 7: Pt layers on the inner and outer surfaces 0.9µm thick by chemical plating
Then deposit at 1000 ℃ and then bake.

Step 8: A first protective layer having a thickness of about 150 μm is formed by plasma spraying with MgO · Al ₂ O ₃ (spinel) powder.

Step 9: Immerse in H ₂ PtCl ₆ solution with Pt of 0.05 g / l, 50 to 100 mmHg
Leave under reduced pressure for about 5 minutes. However, Sample No. 15 is this process 9
Is omitted.

Step 10: After drying, a noble metal-containing titania paste is applied to the surface of the first protective layer, and baked in a reducing atmosphere at 800 ° C. to form a second layer having a thickness of about 25 μm having pores of about 2 μm.
Form a protective layer. The above-mentioned paste is obtained by immersing titania powder in H ₂ PtCl ₆ liquid or Pt black, drying and impregnating with stirring, and then adding an organic binder and a solvent (butyl galbidol).

Further, using the oxygen sensor element 1 thus manufactured, the oxygen sensor A was obtained by the following steps.

Step 11: After the element 1 is inserted into the housing 7, the caulking ring 8 and the filler 9 such as talc are inserted to fix the element 1 in the housing 7.

Step 12: The protective layer 10 is arranged so as to cover the tip of the element 1, and the front end of the housing 7 and the rear end of the protective tube 10 are welded together.

Step 13: A terminal and a lead wire (not shown) are connected to the electrode, and an outer cylinder (not shown) is covered to obtain an oxygen sensor.

[Test Example] The following test was performed based on the oxygen sensor element of the present invention according to the above-mentioned example, and each evaluation item was examined. Also, the comparative example was similarly examined.

Tests 1 and 2 An oxygen sensor element obtained by changing the amount of the precious metal catalyst used in Step 10 and the catalyst loading of the second protective layer was subjected to a durability test with a Bunsen burner. In Test 1, the tip part (tip part) of each oxygen sensor element was heated to 700 to 850 ° C in an incomplete combustion state where almost no air was introduced, and in Test 2 air was introduced and the tip part was almost completely burned. Heated to about 850 ℃, 500H each
rs make it durable.

Evaluation item A: An oxygen sensor equipped with the above heated oxygen sensor element was attached to a combustion tube (inner diameter width 43), and a burner flame was sprayed from a location 1 m away from the sensor to evaluate sensor response.

Evaluation item B: Similarly, the oxygen sensor after heating is mounted at a predetermined position on the actual vehicle of the engine, sensor control is performed, and the λ scan value (control A / F average value) located further downstream is evaluated to evaluate the λ characteristic. .

Evaluation item C: The state of the element surface was visually evaluated.

 The results are shown in Table 1.

As is apparent from Table 1, the oxygen sensor element (and the oxygen sensor) according to the example was compared with that of the comparative example in each test.
Excellent results are shown for each of the evaluation items A, B and C of 1 and 2. It can also be recognized that the amount of catalyst supported on the second protective layer is preferably less than 8.0 mol%.

Test 3 Using an oxygen sensor element in which the respective catalyst loadings of the first and second protective layers were changed, the initial characteristics (before endurance) showed that the frequency of the output signal of the oxygen sensor during sensor control (Hz)
[Evaluation item D].

The oxygen sensor related to the above elements was installed at a predetermined position in the actual vehicle, A / F10 (rich atmosphere), exhaust gas temperature 700
The endurance was performed at 200 ° C for 200 hours and the evaluation items B and C were also examined.

Table 2 also confirms the excellent results of this example. Further, it can be recognized that the catalyst loading amount of the first protective layer is preferably less than 1 wt% under the condition of being exposed to such rich exhaust gas.

[Effects] As described above, according to the present invention, the solid electrolyte body and the protective layer are firmly bonded due to the presence of the spherical projections.
It can prevent peeling of the protective layer and has excellent durability. Moreover, since excessive adsorption and reaction of the unbaked component to the noble metal can be suppressed by the second protective layer (or at least a part of the protective layer, the same hereinafter), the sensor response and the λ characteristic are also excellent, and the space with high accuracy can be obtained. The fuel ratio control can be maintained. First by the second protective layer
Since the catalyst supported on the protective layer is prevented from scattering, the amount of catalyst supported on the first protective layer can be increased, and the catalytic action can maintain the air-fuel ratio control with higher accuracy. Furthermore, in addition to the supported noble metal catalysts of the first and second protective layers, the second protective layer itself also has a catalytic action that promotes the oxidation reaction of the uncalcined component in the gas to be measured, so the entire protective layer shares the catalytic action. As a result, the volume expansion due to the reaction between the catalyst and the unburned components can be suppressed as much as possible, which also contributes to the improvement of durability. Moreover,
Even if the noble metal of the second protective layer sublimes, a sufficient catalytic action can be continuously exerted by the supported catalyst of the first protective layer and the second protective layer itself.

Therefore, according to the present invention, an expensive noble metal can be effectively used to efficiently oxidize unburned components in the gas to be measured, so that highly accurate sensor control can be stably maintained, and thus in the oxygen sensor field. It is extremely useful.

[Brief description of drawings]

1 is a sectional view showing an embodiment of an oxygen sensor element and an oxygen sensor of the present invention, FIG. 2 is an enlarged sectional view of FIG. 1, FIG. 3 is an enlarged sectional view of FIG. FIG. 4 is a half cross-sectional view showing another embodiment of the oxygen sensor element of the present invention, respectively. A ... Oxygen sensor, 1 ... Oxygen sensor element 2 ... Solid electrolyte body, 2a ... Base part 2b ... Spherical projection part, 3 ... Reference electrode 4 ... Measurement electrode, 5 ... Protective layer 5a ... First protective layer, 5b ... Second protection Layer 6 ... Catalyst

Continuation of the front page (56) References JP-A-59-196580 (JP, A) JP-A-56-160653 (JP, A) Actual development Sho-53-65783 (JP, U)

Claims (6)

[Claims] 1. An oxygen sensor element having a reference electrode on one surface side of a solid electrolyte body and a measurement electrode on the other surface side to detect the oxygen concentration of a gas to be measured, wherein the solid electrolyte body is directly bonded to a base portion and the base portion. And a measurement electrode at a position including at least the spherical projection, the measurement electrode is covered with a porous first protective layer, and the first protection layer is a second porous layer. Covered with a protective layer,
At least the second protective layer carries a noble metal catalyst that promotes an oxidation reaction of the gas to be measured, and the first protective layer is made of a metal oxide that is chemically stable to the gas to be measured, An oxygen sensor element, wherein the protective layer is made of a non-stoichiometric transition metal oxide. 2. The oxygen sensor element according to claim 1, wherein the transition metal oxide is titania. 3. The amount of catalyst supported on the second protective layer is
The oxygen sensor element according to claim 1 or 2, wherein the content of the second protective layer is 0.02 to 5 mol% (calculated as a noble metal). 4. A method for producing an oxygen sensor element for detecting an oxygen concentration of a gas to be measured, comprising a reference electrode on one surface side of a solid electrolyte body and a measurement electrode on the other surface side thereof, the method comprising: Regarding the treatment on the surface side, at least the following steps: (a) a step of attaching spherical particles made of a solid electrolyte, (b) a step of forming an electrode, (c) a step of spraying a metal oxide component, (d) A step of immersing in a noble metal salt solution, and (e) a step of coating with a paste-like material containing a stoichiometric transition metal oxide component and a noble metal component, and then firing. , Manufacturing method of oxygen sensor element. 5. The method for producing an oxygen sensor element according to claim 4, wherein in the step (a), the base material of the solid electrolyte and the spherical particles are co-fired. 6. The method for producing an oxygen sensor element according to claim 4, wherein in step (d), the immersion is performed under reduced pressure or pressure.