WO2022196140A1 - センサ素子 - Google Patents
センサ素子 Download PDFInfo
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- WO2022196140A1 WO2022196140A1 PCT/JP2022/003768 JP2022003768W WO2022196140A1 WO 2022196140 A1 WO2022196140 A1 WO 2022196140A1 JP 2022003768 W JP2022003768 W JP 2022003768W WO 2022196140 A1 WO2022196140 A1 WO 2022196140A1
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- Prior art keywords
- protective layer
- sensor element
- layer
- gas
- electrode
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- 239000007789 gas Substances 0.000 claims abstract description 97
- 239000001301 oxygen Substances 0.000 claims abstract description 55
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 55
- 239000007784 solid electrolyte Substances 0.000 claims abstract description 52
- 230000003746 surface roughness Effects 0.000 claims abstract description 26
- 239000011241 protective layer Substances 0.000 claims description 153
- 239000010410 layer Substances 0.000 claims description 102
- 239000011148 porous material Substances 0.000 claims description 15
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 72
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 49
- 238000009792 diffusion process Methods 0.000 description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 32
- 238000005259 measurement Methods 0.000 description 24
- 239000000758 substrate Substances 0.000 description 22
- 125000006850 spacer group Chemical group 0.000 description 15
- 239000002002 slurry Substances 0.000 description 12
- 238000001514 detection method Methods 0.000 description 11
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 10
- 230000035939 shock Effects 0.000 description 10
- 238000000034 method Methods 0.000 description 9
- 239000000919 ceramic Substances 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 238000001035 drying Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 238000007639 printing Methods 0.000 description 5
- 238000001878 scanning electron micrograph Methods 0.000 description 5
- 238000007598 dipping method Methods 0.000 description 4
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- 239000011195 cermet Substances 0.000 description 3
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- 239000000843 powder Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
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- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 230000005856 abnormality Effects 0.000 description 2
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- 238000005498 polishing Methods 0.000 description 2
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- 230000001681 protective effect Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
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- 229920005989 resin Polymers 0.000 description 2
- 229910020068 MgAl Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
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- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000010349 pulsation Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
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- 239000003381 stabilizer Substances 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
- G01N27/4071—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure
- G01N27/4072—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure characterized by the diffusion barrier
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
- G01N27/4077—Means for protecting the electrolyte or the electrodes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/4067—Means for heating or controlling the temperature of the solid electrolyte
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
- G01N27/4073—Composition or fabrication of the solid electrolyte
- G01N27/4074—Composition or fabrication of the solid electrolyte for detection of gases other than oxygen
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
- G01M15/04—Testing internal-combustion engines
- G01M15/10—Testing internal-combustion engines by monitoring exhaust gases or combustion flame
- G01M15/102—Testing internal-combustion engines by monitoring exhaust gases or combustion flame by monitoring exhaust gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
- G01N27/41—Oxygen pumping cells
Definitions
- the present invention relates to a sensor element, and more particularly to a sensor element used for measuring the concentration of a predetermined gas component in a gas to be measured.
- Patent Document 1 discloses a gas sensor configured to measure the concentration of a predetermined gas component in a gas to be measured.
- This gas sensor includes a sensor element.
- a protective film is formed on the tip portion of the sensor element in order to suppress thermal shock caused by the sensor element getting wet (see Patent Document 1).
- a gas sensor including a sensor element is attached, for example, to an exhaust pipe of an engine.
- a gas sensor including a sensor element is attached, for example, to an exhaust pipe of an engine.
- the present invention was made to solve such problems, and its object is to provide a sensor element that is less susceptible to thermal shock due to exposure to water.
- a sensor element is used to measure the concentration of a predetermined gas component in the gas to be measured.
- This sensor element includes a plate-like element body and a protective layer.
- the element body includes a solid electrolyte layer having oxygen ion conductivity and a heater configured to heat the solid electrolyte layer.
- a protective layer is formed on at least one surface of the element body.
- the surface of the protective layer has a surface roughness Ra of 8 ⁇ m or less and a surface waviness Wa of 6 ⁇ m or more.
- the surface of the protective layer has a relatively small surface roughness Ra and a relatively large surface waviness Wa. Therefore, it is difficult for the moisture dropped on the surface of the protective layer to remain in one place. As a result, according to this sensor element, there is a high possibility that moisture that has dripped onto the surface of the protective layer will move to a portion other than the sensor element, so that thermal shock due to exposure to water can be suppressed.
- the element body has long sides and short sides in plan view, and each of the surface roughness Ra and the surface waviness Wa may be obtained from the cross-sectional curve of the protective layer in the short side direction.
- the position corresponding to the central portion of the protective layer in the short-side direction of the element body may be raised more than the positions corresponding to both ends of the protective layer in the short-side direction.
- the protective layer includes an inner protective layer and an outer protective layer located outside the inner protective layer, each of the inner protective layer and the outer protective layer being porous.
- the average pore diameter may be smaller than the average pore diameter of the inner protective layer, and the porosity of the inner protective layer may be 40% or more and 60% or less.
- the film thickness of the inner protective layer may be 170 ⁇ m or more and 900 ⁇ m or less.
- the outer protective layer may have a porosity of 15% or more and 50% or less.
- the film thickness of the outer protective layer may be 30 ⁇ m or more and 300 ⁇ m or less.
- FIG. 2 is a diagram schematically showing the IV-IV cross section of FIG. 1; 1 is a schematic cross-sectional view schematically showing an example of the configuration of a gas sensor including a sensor element with a three-chamber structure; FIG. FIG. 4 is a diagram for explaining a method of measuring surface roughness Ra and surface waviness Wa; It is a figure which shows typically the apparatus used in a water resistance test.
- FIG. 1 is a perspective view schematically showing an example of sensor element 101 according to this embodiment.
- FIG. 2 is a schematic cross-sectional view schematically showing an example of the configuration of the gas sensor 100 including the sensor element 101.
- the cross section of the sensor element 101 in FIG. 2 corresponds to the II-II cross section in FIG.
- the sensor element 101 has an elongated rectangular parallelepiped shape.
- the sensor element 101 has long sides and short sides.
- the longitudinal direction of the sensor element 101 horizontal direction in FIG. 2
- the thickness direction of the sensor element 101 vertical direction in FIG. 2
- the direction of the short side of the sensor element 101 is defined as the left-right direction.
- a gas sensor 100 is attached to, for example, an exhaust pipe of a vehicle, and configured to measure the concentration of a specific gas such as NOx or O2 contained in the exhaust gas as the gas to be measured. It is In the present embodiment, the gas sensor 100 measures the NOx concentration as the specific gas concentration.
- the sensor element 101 includes an element body 101a and a protective layer 90 covering the element body 101a. Note that the element main body 101 a is a portion of the sensor element 101 other than the protective layer 90 .
- the sensor element 101 includes a first substrate layer 1, a second substrate layer 2, a third substrate layer 3, and a first solid electrolyte layer 4 each made of an oxygen ion conductive solid electrolyte layer such as zirconia (ZrO2). , a spacer layer 5, and a second solid electrolyte layer 6 are stacked in this order from the lower side as seen in the drawing. Also, the solid electrolyte forming these six layers is dense and airtight.
- the sensor element 101 is manufactured by, for example, performing predetermined processing and circuit pattern printing on ceramic green sheets corresponding to each layer, laminating them, and firing them to integrate them.
- a gas introduction port 10 Between the lower surface of the second solid electrolyte layer 6 and the upper surface of the first solid electrolyte layer 4 at one end of the sensor element 101, there are provided a gas introduction port 10, a first diffusion control section 11, and a buffer space. 12, a second diffusion rate-limiting portion 13, a first internal space 20, a third diffusion rate-limiting portion 30, and a second internal space 40 are formed adjacent to each other in a manner communicating with each other in this order.
- the gas introduction port 10 , the buffer space 12 , the first internal space 20 , and the second internal space 40 are formed by hollowing out the spacer layer 5 .
- the space inside the sensor element 101 is defined by the upper surface of the first solid electrolyte layer 4 at the bottom and the side surface of the spacer layer 5 at the side.
- Each of the first diffusion rate-controlling part 11, the second diffusion rate-controlling part 13, and the third diffusion rate-controlling part 30 is provided as two horizontally long slits (the openings of which have the longitudinal direction in the direction perpendicular to the drawing). .
- a portion from the gas introduction port 10 to the second internal space 40 is also called a gas circulation portion.
- a reference gas introduction space 43 is provided at a position where the reference gas is introduced.
- air is introduced into the reference gas introduction space 43 .
- the first solid electrolyte layer 4 may extend to the rear end of the sensor element 101 and the reference gas introduction space 43 may not be formed.
- the atmosphere introduction layer 48 may extend to the rear end of the sensor element 101 (see FIG. 5, for example).
- the atmosphere introduction layer 48 is a layer made of porous alumina, and the reference gas is introduced into the atmosphere introduction layer 48 through the reference gas introduction space 43 . Also, the atmosphere introduction layer 48 is formed so as to cover the reference electrode 42 .
- the reference electrode 42 is an electrode formed in a manner sandwiched between the upper surface of the third substrate layer 3 and the first solid electrolyte layer 4, and as described above, is connected to the reference gas introduction space 43 around it.
- An atmosphere introduction layer 48 is provided. Further, as will be described later, it is possible to measure the oxygen concentration (oxygen partial pressure) in the first internal space 20 and the second internal space 40 using the reference electrode 42 .
- the gas introduction port 10 is a portion that opens to the external space, and the gas to be measured is taken into the sensor element 101 from the external space through the gas introduction port 10 .
- the first diffusion control section 11 is a section that imparts a predetermined diffusion resistance to the gas to be measured introduced from the gas inlet 10 .
- the buffer space 12 is a space provided for guiding the gas to be measured introduced from the first diffusion control section 11 to the second diffusion control section 13 .
- the second diffusion control section 13 is a section that imparts a predetermined diffusion resistance to the gas under measurement introduced from the buffer space 12 into the first internal space 20 .
- the pressure fluctuation of the gas to be measured in the external space (the pulsation of the exhaust pressure if the gas to be measured is the exhaust gas of an automobile) ) is not introduced directly into the first internal space 20, but rather into the first diffusion rate-determining portion 11, the buffer space 12, the second After concentration fluctuations of the gas to be measured are canceled out through the diffusion control section 13 , the gas is introduced into the first internal cavity 20 .
- fluctuations in the concentration of the gas to be measured introduced into the first internal space are almost negligible.
- the first internal space 20 is provided as a space for adjusting the oxygen partial pressure in the gas to be measured introduced through the second diffusion control section 13 .
- the oxygen partial pressure is adjusted by operating the main pump cell 21 .
- the main pump cell 21 includes an inner pump electrode 22 having a ceiling electrode portion 22a provided on substantially the entire lower surface of the second solid electrolyte layer 6 facing the first internal cavity 20, and an upper surface of the second solid electrolyte layer 6.
- An electrochemical pump cell comprising an outer pump electrode 23 provided in a region corresponding to the ceiling electrode portion 22a in a manner exposed to the external space, and a second solid electrolyte layer 6 sandwiched between these electrodes.
- the inner pump electrode 22 is formed across the upper and lower solid electrolyte layers (the second solid electrolyte layer 6 and the first solid electrolyte layer 4) that define the first internal cavity 20 and the spacer layer 5 that provides side walls.
- a ceiling electrode portion 22a is formed on the lower surface of the second solid electrolyte layer 6 that provides the ceiling surface of the first internal cavity 20
- a bottom electrode portion 22a is formed on the upper surface of the first solid electrolyte layer 4 that provides the bottom surface.
- a spacer layer in which electrode portions 22b are formed, and side electrode portions (not shown) constitute both side wall portions of the first internal cavity 20 so as to connect the ceiling electrode portion 22a and the bottom electrode portion 22b. 5, and arranged in a tunnel-shaped structure at the arrangement portion of the side electrode portion.
- the inner pump electrode 22 and the outer pump electrode 23 are formed as porous cermet electrodes (for example, cermet electrodes of Pt and ZrO 2 containing 1% Au).
- the inner pump electrode 22 that comes into contact with the gas to be measured is made of a material that has a weakened ability to reduce NOx components in the gas to be measured.
- a desired pump voltage Vp0 is applied between the inner pump electrode 22 and the outer pump electrode 23 to generate a positive or negative pump current between the inner pump electrode 22 and the outer pump electrode 23.
- Ip0 By flowing Ip0, it is possible to pump oxygen in the first internal space 20 to the external space, or to pump oxygen in the external space into the first internal space 20 .
- the third substrate layer 3 and the reference electrode 42 constitute an electrochemical sensor cell, that is, an oxygen partial pressure detection sensor cell 80 for main pump control.
- the oxygen concentration (oxygen partial pressure) in the first internal space 20 can be known. Furthermore, the pump current Ip0 is controlled by feedback-controlling Vp0 so that the electromotive force V0 is constant. Thereby, the oxygen concentration in the first internal cavity 20 can be maintained at a predetermined constant value.
- the third diffusion rate controlling section 30 applies a predetermined diffusion resistance to the gas under measurement whose oxygen concentration (oxygen partial pressure) is controlled by the operation of the main pump cell 21 in the first internal cavity 20, thereby reducing the gas under measurement. It is a portion that leads to the second internal space 40 .
- the second internal space 40 is provided as a space for performing processing related to measurement of nitrogen oxide (NOx) concentration in the gas to be measured introduced through the third diffusion control section 30 .
- NOx concentration is measured mainly in the second internal space 40 where the oxygen concentration is adjusted by the auxiliary pump cell 50 and further by the operation of the measuring pump cell 41 .
- the gas to be measured introduced through the third diffusion control section is further pumped by the auxiliary pump cell 50.
- Oxygen partial pressure is adjusted.
- the oxygen concentration in the second internal space 40 can be kept constant with high accuracy, so that the gas sensor 100 can measure the NOx concentration with high accuracy.
- the auxiliary pump cell 50 includes an auxiliary pump electrode 51 having a ceiling electrode portion 51a provided on substantially the entire lower surface of the second solid electrolyte layer 6 facing the second internal cavity 40, and an outer pump electrode 23 (outer pump electrode 23 any suitable electrode outside the sensor element 101 ) and the second solid electrolyte layer 6 .
- the auxiliary pump electrode 51 is arranged in the second internal space 40 in the same tunnel-like structure as the inner pump electrode 22 provided in the first internal space 20 . That is, the ceiling electrode portion 51a is formed on the second solid electrolyte layer 6 that provides the ceiling surface of the second internal space 40, and the first solid electrolyte layer 4 that provides the bottom surface of the second internal space 40 has , bottom electrode portions 51b are formed, and side electrode portions (not shown) connecting the ceiling electrode portions 51a and the bottom electrode portions 51b are formed on the spacer layer 5 that provides the sidewalls of the second internal cavity 40. It has a tunnel-like structure formed on both walls.
- auxiliary pump electrode 51 is also formed using a material that has a weakened ability to reduce NOx components in the gas to be measured, similarly to the inner pump electrode 22 .
- auxiliary pump cell 50 by applying a desired voltage Vp1 between the auxiliary pump electrode 51 and the outer pump electrode 23, oxygen in the atmosphere inside the second internal cavity 40 is pumped out to the external space, or It is possible to pump from the space into the second internal cavity 40 .
- the auxiliary pump electrode 51, the reference electrode 42, the second solid electrolyte layer 6, the spacer layer 5, and the first solid electrolyte constitute an electrochemical sensor cell, that is, an oxygen partial pressure detection sensor cell 81 for controlling the auxiliary pump.
- the auxiliary pump cell 50 performs pumping with the variable power supply 52 whose voltage is controlled based on the electromotive force V1 detected by the oxygen partial pressure detection sensor cell 81 for controlling the auxiliary pump. Thereby, the oxygen partial pressure in the atmosphere inside the second internal cavity 40 is controlled to a low partial pressure that does not substantially affect the measurement of NOx.
- the pump current Ip1 is used to control the electromotive force of the oxygen partial pressure detection sensor cell 80 for main pump control.
- the pump current Ip1 is input as a control signal to the oxygen partial pressure detection sensor cell 80 for controlling the main pump, and the electromotive force V0 thereof is controlled so that the current from the third diffusion rate-determining section 30 to the second internal space is
- the gradient of the oxygen partial pressure in the gas to be measured introduced into 40 is controlled so that it is always constant.
- the main pump cell 21 and the auxiliary pump cell 50 work to keep the oxygen concentration in the second internal cavity 40 at a constant value of approximately 0.001 ppm.
- the measuring pump cell 41 measures the NOx concentration in the gas to be measured within the second internal space 40 .
- the measurement pump cell 41 includes a measurement electrode 44 provided on the upper surface of the first solid electrolyte layer 4 facing the second internal cavity 40 and at a position spaced apart from the third diffusion control section 30 , and an outer pump electrode 23 . , a second solid electrolyte layer 6 , a spacer layer 5 and a first solid electrolyte layer 4 .
- the measurement electrode 44 is a porous cermet electrode.
- the measurement electrode 44 also functions as a NOx reduction catalyst that reduces NOx present in the atmosphere within the second internal cavity 40 . Furthermore, the measurement electrode 44 is covered with a fourth diffusion control section 45 .
- the fourth diffusion rate-controlling part 45 is a film composed of a porous material containing alumina (Al 2 O 3 ) as a main component.
- the fourth diffusion control section 45 plays a role of limiting the amount of NOx flowing into the measurement electrode 44 and also functions as a protective film for the measurement electrode 44 .
- oxygen generated by the decomposition of nitrogen oxides in the atmosphere around the measurement electrode 44 can be pumped out, and the amount of oxygen generated can be detected as the pump current Ip2.
- the reference electrode 42 and the electrochemical sensor cell constitute an oxygen partial pressure detection sensor cell 82 for controlling the measuring pump.
- the variable power supply 46 is controlled based on the electromotive force V2 detected by the oxygen partial pressure detection sensor cell 82 for controlling the measuring pump.
- the measured gas guided into the second internal space 40 reaches the measuring electrode 44 through the fourth diffusion control section 45 under the condition that the oxygen partial pressure is controlled.
- Nitrogen oxides in the gas to be measured around the measuring electrode 44 are reduced (2NO ⁇ N 2 +O 2 ) to generate oxygen.
- the generated oxygen is pumped by the measuring pump cell 41.
- the variable power supply is controlled so that the control voltage V2 detected by the measuring pump control oxygen partial pressure detecting sensor cell 82 is kept constant. is controlled. Since the amount of oxygen generated around the measuring electrode 44 is proportional to the concentration of nitrogen oxides in the gas to be measured, the pump current Ip2 in the pump cell 41 for measurement is used to measure the nitrogen oxides in the gas to be measured. The concentration will be calculated.
- the measuring electrode 44, the first solid electrolyte layer 4, the third substrate layer 3, and the reference electrode 42 are combined to constitute an oxygen partial pressure detecting means as an electrochemical sensor cell, the measuring electrode It is possible to detect the electromotive force corresponding to the difference between the amount of oxygen generated by the reduction of the NOx component in the atmosphere around 44 and the amount of oxygen contained in the reference atmosphere, thereby detecting the NOx component in the gas to be measured. It is also possible to obtain the concentration of
- An electrochemical sensor cell 83 is composed of the second solid electrolyte layer 6, the spacer layer 5, the first solid electrolyte layer 4, the third substrate layer 3, the outer pump electrode 23, and the reference electrode 42.
- the oxygen partial pressure in the gas to be measured outside the sensor can be detected from the electromotive force Vref obtained by the sensor cell 83 .
- the oxygen partial pressure is always kept at a constant low value (a value that does not substantially affect NOx measurement).
- a gas to be measured is supplied to the measuring pump cell 41 . Therefore, the NOx concentration in the gas to be measured is determined based on the pump current Ip2 that flows when the oxygen generated by the reduction of NOx is pumped out of the measuring pump cell 41 in substantially proportion to the concentration of NOx in the gas to be measured. It is possible to know.
- the sensor element 101 is provided with a heater section 70 that plays a role of temperature adjustment for heating and keeping the sensor element 101 warm in order to increase the oxygen ion conductivity of the solid electrolyte.
- the heater section 70 includes heater electrodes 71 , heaters 72 , through holes 73 , heater insulating layers 74 , and pressure dissipation holes 75 .
- the heater electrode 71 is an electrode formed so as to be in contact with the bottom surface of the first substrate layer 1 . By connecting the heater electrode 71 to an external power source, power can be supplied to the heater section 70 from the outside.
- the heater 72 is an electric resistor that is sandwiched between the second substrate layer 2 and the third substrate layer 3 from above and below.
- the heater 72 is connected to the heater electrode 71 through the through hole 73 , and generates heat when supplied with power from the outside through the heater electrode 71 to heat the solid electrolyte forming the sensor element 101 and keep it warm.
- the heater 72 is embedded over the entire area from the first internal space 20 to the second internal space 40, and it is possible to adjust the entire sensor element 101 to a temperature at which the solid electrolyte is activated. ing.
- the heater insulating layer 74 is an insulating layer formed on the upper and lower surfaces of the heater 72 with an insulator such as alumina.
- the heater insulating layer 74 is formed for the purpose of providing electrical insulation between the second substrate layer 2 and the heater 72 and electrical insulation between the third substrate layer 3 and the heater 72 .
- the pressure dissipation hole 75 is a portion that penetrates the third substrate layer 3 and is provided so as to communicate with the reference gas introduction space 43.
- the pressure dissipation hole 75 is provided for the purpose of alleviating an increase in internal pressure accompanying a temperature increase in the heater insulating layer 74. formed.
- the element main body 101a is partially covered with the protective layer 90 .
- the protective layer 90 covers five of the six surfaces of the element body 101a. That is, the protective layer 90 covers each of the upper surface, lower surface, left surface, right surface and front surface of the element body 101a.
- the protective layer 90 is made of a porous material, such as ceramics containing ceramic particles.
- the ceramic particles include metal oxide particles such as alumina (Al 2 O 3 ), zirconia (ZrO 2 ), spinel (MgAl 2 O 4 ), mullite (Al 6 O 13 Si 2 ). preferably contains at least one of these.
- the protective layer 90 is made of an alumina porous body.
- the protective layer 90 covers the entire surface of the element body 101a from the front end surface of the element body 101a to the distance L (see FIG. 2) rearward. Moreover, the protective layer 90 covers the portion where the outer pump electrode 23 is formed. The protective layer 90 covers the gas inlet 10 , but since the protective layer 90 is made of a porous material, the gas to be measured can flow through the protective layer 90 and reach the gas inlet 10 . be.
- the protective layer 90 covers a portion of the element body 101a (the portion from the front end face to the distance L including the front end face of the element body 101a) to protect that portion.
- the protective layer 90 prevents, for example, moisture in the gas to be measured from adhering to the element body 101a and cracking the element body 101a.
- the distance L is determined based on the range in which the element body 101a is exposed to the gas to be measured in the gas sensor 100, the position of the outer pump electrode 23, and the like (0 ⁇ distance L ⁇ the length of the element body 101a in the long side direction ).
- the protective layer 90 has a two-layer structure.
- the protective layer 90 includes a porous outer protective layer 91 and a porous inner protective layer 92 .
- the inner protective layer 92 partially covers the surface of the element body 101a.
- the outer protective layer 91 is positioned outside the inner protective layer 92 with respect to the element main body 101 a and is laminated on the inner protective layer 92 .
- the outer protective layer 91 has a smaller average pore size than the inner protective layer 92 . That is, the ratio R1/R2 between the average pore diameter R1 ⁇ m of the outer protective layer 91 and the average pore diameter R2 ⁇ m of the inner protective layer 92 is less than 1.0.
- the thickness Th1 of the outer protective layer 91 may be 30 ⁇ m or more, 50 ⁇ m or more, 300 ⁇ m or less, 200 ⁇ m or less, 150 ⁇ m or less, or 100 ⁇ m or less. Note that the thickness Th1 does not necessarily have to be uniform throughout the outer protective layer 91 .
- the thickness Th2 of the inner protective layer 92 may be 170 ⁇ m or more, 200 ⁇ m or more, 250 ⁇ m or more, 900 ⁇ m or less, or 400 ⁇ m or less. Note that the thickness Th2 does not necessarily have to be uniform throughout the inner protective layer 92 .
- each of the thickness Th1 of the outer protective layer 91 and the thickness Th2 of the inner protective layer 92 is a value derived as follows. First, the sensor element 101 is cut along the thickness direction of the outer protective layer 91 . An observation sample is prepared by filling the cut surface with resin and polishing the cut surface. Subsequently, the magnification of the SEM (Scanning Electron Microscope) is set to 1000 times, and the observation surface of the observation sample (the cross section of the outer protective layer 91) is photographed. An SEM image of the outer protective layer 91 is thereby obtained.
- SEM Sccanning Electron Microscope
- the outer protective layer 91 (for example, the portion located above the second solid electrolyte layer 6) and the inner protective layer 92 (for example, the portion located above the second solid electrolyte layer 6) ) is identified.
- the direction perpendicular to the surface of the element body 101a on which the protective layer 90 is formed (for example, the upper surface of the second solid electrolyte layer 6) is specified as the thickness direction.
- the distance in the thickness direction from the surface (here, the upper surface) of the protective layer 90 to the boundary is derived as the thickness Th1.
- the distance in the thickness direction from the surface of the element body 101a to the boundary is derived as the thickness Th2. Acquisition of the SEM image can be performed using, for example, SU1510 manufactured by Hitachi High-Technologies.
- the outer protective layer 91 preferably has a porosity Po1 of 30% or more.
- the porosity Po1 is 30% or more, the pore volume in the outer protective layer 91 is less likely to be insufficient with respect to the water content, and the outer protective layer 91 can sufficiently retain water.
- the outer protective layer 91 preferably has a porosity Po1 of 50% or less. If the porosity Po1 is 50% or less, it becomes difficult for water to pass through the outer protective layer 91, and the outer protective layer 91 can sufficiently retain water.
- the inner protective layer 92 preferably has a porosity Po2 of 40% or more. If the porosity Po2 is 40% or more, it is possible to prevent the heat insulation effect of the inner protective layer 92 between the outer protective layer 91 and the element main body 101a from becoming insufficient. In addition, the inner protective layer 92 preferably has a porosity Po2 of 60% or less. If the porosity Po2 is 60% or less, it is possible to prevent the strength of the inner protective layer 92 from becoming insufficient.
- the porosity Po1 of the outer protective layer 91 is a value derived as follows. First, the sensor element 101 is cut along the thickness direction of the outer protective layer 91 . An observation sample is prepared by filling the cut surface with resin and polishing the cut surface. Subsequently, the magnification of the SEM is set to 100 times, and the observation surface (the cross section of the outer protective layer 91) of the observation sample is photographed. An SEM image of the outer protective layer 91 is thereby obtained. Image analysis of the obtained SEM image is performed. A threshold value is determined by discriminant analysis based on the luminance distribution of the pixels in the image.
- each pixel in the image is binarized into the object portion and the pore portion based on the determined threshold, and the area of the object portion and the area of the pore portion are calculated. Then, the ratio of the area of the pore portion to the total area (the total area of the body portion and the pore portion) is derived as the porosity Po1.
- the porosity Po2 of the inner protective layer 92 is also a value derived in the same manner.
- Gas sensor 100 is attached, for example, to an exhaust pipe of a vehicle engine. In recent years, it is required to start the gas sensor 100 early after starting the engine. In other words, it is required to advance the temperature rise timing of the sensor element 101 after the engine is started.
- FIG. 3 is a diagram showing an example of how the temperature of the sensor element 101 and the like changes.
- the horizontal axis indicates time and the vertical axis indicates temperature.
- a line W2 indicates an example of temperature change of the sensor element 101, and a line W1 indicates an example of temperature change of the sensor element to be compared.
- a line W3 represents an example of the temperature change of the exhaust gas passing through the exhaust pipe of the engine.
- the engine starts.
- condensed water exists in the exhaust pipe.
- the condensed water scatters in the exhaust pipe and enters the gas sensor 100 .
- the inside of the gas sensor 100 becomes dry at time t2, for example.
- the temperature of the sensor element to be compared starts rising after the inside of the gas sensor 100 becomes dry (time t2). Thereafter, the temperature of the sensor element to be compared reaches temperature T2 at time t3.
- Temperature T2 is the temperature required for the gas sensor to function. Since the temperature of the sensor element to be compared starts rising after the inside of the gas sensor 100 becomes dry, the possibility of cracks occurring in the sensor element to be compared is low. However, the sensor element to be compared cannot function until time t3.
- the temperature of the sensor element 101 starts rising at the same time as the engine is started (time t0), for example.
- the temperature of sensor element 101 reaches temperature T2 at time t1. That is, the temperature rise timing of the sensor element 101 is earlier than the temperature rise timing of the sensor element to be compared.
- sensor element 101 is structurally devised. As a result, cracks are less likely to occur in the sensor element 101 even if the gas sensor 100 is started early after the engine is started. Structural improvements in the sensor element 101 will be described in detail below.
- FIG. 4 is a diagram schematically showing the IV-IV cross section of FIG. Note that the structure of the element body 101a is simplified in FIG.
- the structure of the upper surface of protective layer 90 is devised. Specifically, in the short side direction of the sensor element 101, the surface roughness Ra of the upper surface of the protective layer 90 is 8 ⁇ m or less, and the surface waviness Wa of the upper surface of the protective layer 90 is 6 ⁇ m or more.
- the surface roughness Ra of the upper surface of the protective layer 90 is 7.6 ⁇ m or less, and the surface waviness Wa of the upper surface of the protective layer 90 is 6.9 ⁇ m or more.
- each of the surface roughness Ra and the surface waviness Wa complies with the definition in JIS B0633:2001. That is, the surface roughness Ra means the arithmetic mean height of the roughness curve, and the surface waviness Wa means the arithmetic mean height of the waviness curve.
- Each of the roughness curve and the waviness curve is obtained from the cross-sectional curve of the protective layer 90 in the short side direction.
- the upper surface of the protective layer 90 has a relatively small surface roughness Ra and a relatively large surface waviness Wa. Therefore, the water droplets Wt1 dropped on the upper surface of the protective layer 90 are greatly affected by the Leidenfrost phenomenon and are less likely to stay in one place on the upper surface of the protective layer 90 . As a result, according to the sensor element 101, there is a high possibility that the water droplet Wt1 dropped on the upper surface of the protective layer 90 will move to a portion other than the sensor element 101, so that thermal shock due to exposure to water can be suppressed.
- the position P1 corresponding to the central portion of the protective layer 90 in the short side direction is raised more than the positions P2 corresponding to both ends of the protective layer 90 in the short side direction.
- the water droplets Wt1 dropped on the upper surface of the protective layer 90 are greatly affected by the Leidenfrost phenomenon, flow toward the ends of the protective layer 90 in the short side direction, and reach the sensor element 101. Since there is a high possibility of moving to other parts, it is possible to suppress thermal shock due to water exposure.
- the position in the vertical direction gradually decreases from position P1 to position P2. There may be a portion where the position in the vertical direction rises. Also, in the region between the positions P1 and P2, there may be a region located above the position P1 in the vertical direction.
- the surface of protective layer 90 has surface roughness Ra of 8 ⁇ m or less and surface waviness Wa of 6 ⁇ m or more. That is, the surface of the protective layer 90 has a relatively small surface roughness Ra and a relatively large surface waviness Wa. Therefore, it is difficult for the moisture dropped on the surface of the protective layer 90 to remain in one place. As a result, according to the sensor element 101, there is a high possibility that the moisture that has dripped onto the surface of the protective layer 90 will move to a portion other than the sensor element 101, so it is possible to suppress thermal shock due to water exposure.
- the sensor element 101 is formed with the first internal cavity 20 and the second internal cavity 40 . That is, the sensor element 101 had a two-chamber structure. However, the sensor element 101 does not necessarily have to have a two-chamber structure. For example, sensor element 101 may have a three-chamber structure.
- FIG. 5 is a schematic cross-sectional view schematically showing an example of the configuration of a gas sensor 100X including a sensor element 101X with a three-chamber structure.
- the second internal space 40 (FIG. 1) is further divided into two chambers by the fifth diffusion control section 60 to create a second internal space 40X and a third internal space 61.
- the auxiliary pump electrode 51X may be arranged in the second internal space 40X
- the measurement electrode 44X may be arranged in the third internal space 61.
- the fourth diffusion control section 45 may be omitted.
- the upper surface of the protective layer 90 has a surface roughness Ra of 8 ⁇ m or less and a surface waviness Wa of 6 ⁇ m or more. Some or all of them may have a surface roughness Ra of 8 ⁇ m or less and a surface waviness Wa of 6 ⁇ m or more.
- a sensor element 101 as an example was manufactured by the method described below. Specifically, first, the element body 101a was manufactured, and the sensor element 101 was manufactured by forming the protective layer 90 on the element body 101a.
- each ceramic green sheet was formed by mixing zirconia particles to which 4 mol % of yttria as a stabilizer was added, an organic binder, and an organic solvent, and forming the mixture by tape forming.
- the green sheet to be the spacer layer 5 was previously provided with a space to serve as a gas circulation portion by punching or the like.
- the first substrate layer 1, the second substrate layer 2, the third substrate layer 3, the first solid electrolyte layer 4, the spacer layer 5, and the second solid electrolyte layer 6, A pattern printing process for forming various patterns on each ceramic green sheet and a drying process were performed.
- the patterns formed were the patterns of the above-described electrodes, lead wires connected to the electrodes, the atmosphere introduction layer 48, the heater section 70, and the like.
- Pattern printing was performed by applying a pattern forming paste prepared according to the properties required for each object to be formed onto the green sheet using a known screen printing technique. The drying treatment was also carried out using a known drying means. After pattern printing and drying, an adhesive paste for laminating and bonding the green sheets corresponding to each layer was printed and dried.
- the green sheets on which the adhesive paste was formed were laminated in a predetermined order while being positioned by the sheet holes, and were crimped by applying predetermined temperature and pressure conditions to form a single laminate.
- the laminate thus obtained included a plurality of element bodies 101a.
- the laminate was cut into pieces having the size of the element body 101a. Then, the cut laminate was fired at a predetermined firing temperature to obtain the element body 101a.
- the protective layer 90 was formed by the dipping method using the outer protective layer slurry and the inner protective layer slurry for the outer protective layer 91 and the inner protective layer 92 .
- the slurry for the outer protective layer was prepared by, for example, dispersing raw material powder (alumina) of the outer protective layer 91 and a pore-forming material in a solvent.
- the slurry for the inner protective layer was also the same except that the powder for the inner protective layer 92 was used as the raw material powder.
- the surface of the solid electrolyte layer (layers 1 to 6) of the element body 101a was coated by dipping using the inner protective layer slurry to form a film. Dipping was performed as follows. First, the front end surface of the element body 101a is directed downward, and the element body 101a is immersed perpendicularly to the surface of the inner protective layer slurry. At this time, the region from the front end of the element body 101a to the distance L was immersed in the inner protective layer slurry. Then, the element body 101a was moved backward and slowly pulled up from the inner protective layer slurry.
- the region from the front end of the element main body 101a to the rearward distance L was covered with the film made of the inner protective layer slurry. After pulling up the element main body 101a, the coating was dried. After drying, the outer protective layer slurry was used to form a coating by dipping and drying in the same manner.
- the films were fired at a predetermined firing temperature. As a result, the film was sintered to form the protective layer 90 having the outer protective layer 91 and the inner protective layer 92, and the sensor element 101 was obtained. The surface of the obtained sensor element 101 was polished as necessary.
- Example 1 the surface roughness Ra of the upper surface of the protective layer 90 was 7.6 ⁇ m, and the surface waviness Wa of the upper surface of the protective layer 90 was 6.2 ⁇ m.
- Example 2 the surface roughness Ra of the upper surface of the protective layer 90 was 7.1 ⁇ m, and the surface waviness Wa of the upper surface of the protective layer 90 was 6.9 ⁇ m.
- Example 3 the surface roughness Ra of the upper surface of the protective layer 90 was 7.3 ⁇ m, and the surface waviness Wa of the upper surface of the protective layer 90 was 9.4 ⁇ m.
- Example 4 the surface roughness Ra of the upper surface of the protective layer 90 was 7.7 ⁇ m, and the surface waviness Wa of the upper surface of the protective layer 90 was 7.5 ⁇ m.
- Example 5 the surface roughness Ra of the upper surface of the protective layer 90 was 7.6 ⁇ m, and the surface waviness Wa of the upper surface of the protective layer 90 was 8.6 ⁇ m.
- the surface roughness Ra and surface waviness Wa were each measured according to JIS B0633:2001.
- FIG. 6 is a diagram for explaining a method of measuring surface roughness Ra and surface waviness Wa.
- the line roughness was measured for ten lines EL1 in the short side direction of the sensor element 101 after setting the cutoff value specified in the JIS standard.
- the average values of the measurement results for ten lines EL1 were taken as the surface roughness Ra and the surface waviness Wa.
- VR-3000 manufactured by Keyence Corporation was used for the measurement of line roughness.
- the sensor element in Comparative Example 1 was also manufactured in the same manner as described above. On the upper surface of the protective layer, the surface roughness Ra and the surface waviness Wa were different from those of Examples 1-5. In Comparative Example 1, the surface roughness Ra of the upper surface of the protective layer was 8.6 ⁇ m, and the surface waviness Wa of the upper surface of the protective layer was 5.1 ⁇ m.
- FIG. 7 is a diagram schematically showing an apparatus used in the water resistance test.
- dispenser 500 includes head 510 and nozzle 520 .
- the sensor element 101 is held by an element clamp 530 .
- the liquid is supplied from the liquid reservoir to the nozzle 520 having an inner diameter of 3 mm or less. Specifically, the liquid is supplied to the nozzle 520 by pressurizing with a pressure that is 1-10 kPa higher than the atmospheric pressure. Using dripping, one droplet of a desired amount set in the range of 3 to 70 ⁇ L is dropped from the tip of the nozzle 520 onto the sensor element 101 (protective layer 90). The influence of dropping droplets on the sensor element 101 is evaluated.
- droplets are dropped on the upper surface of the protective layer 90 of the sensor element 101 by opening the nozzle for a first predetermined time. If no abnormality occurs in the sensor element 101, droplets are dropped onto a predetermined position of the sensor element 101 for a second predetermined time longer than the first predetermined time. This operation is repeated until an abnormality occurs in the sensor element 101, or until all predetermined patterns of predetermined time are completed.
- Test result> The test results are summarized in Table 1 below.
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Abstract
Description
図1は、本実施の形態に従うセンサ素子101の一例を概略的に示した斜視図である。図2は、センサ素子101を含むガスセンサ100の構成の一例を概略的に示した断面模式図である。図2のうち、センサ素子101の断面は図1のII-II断面に相当する。なお、センサ素子101は、長尺な直方体形状を有している。平面視において、センサ素子101は、長辺及び短辺を有している。以下においては、センサ素子101の長辺方向(図2の左右方向)を前後方向とする場合があり、センサ素子101の厚み方向(図2の上下方向)を上下方向とする場合がある。また、センサ素子101の短辺方向(前後方向及び上下方向に垂直な方向)を左右方向とする場合がる。
ガスセンサ100は、例えば、車両のエンジンの排気管に取り付けられる。近年、エンジンの始動後にガスセンサ100を早期に始動させることが求められている。すなわち、エンジンの始動後において、センサ素子101の昇温タイミングを早めることが求められている。
図4は、図1のIV-IV断面を模式的に示す図である。なお、図4においては、素子本体101aの構造が簡略化されている。図4を参照して、センサ素子101においては、保護層90の上面の構造に工夫が施されている。具体的には、センサ素子101の短辺方向において、保護層90の上面の表面粗さRaは8μm以下であり、保護層90の上面の表面うねりWaは6μm以上である。好ましくは、保護層90の上面の表面粗さRaは7.6μm以下であり、保護層90の上面の表面うねりWaは6.9μm以上である。なお、表面粗さRa及び表面うねりWaの各々は、JIS B0633:2001における定義に従う。すなわち、表面粗さRaは粗さ曲線の算術平均高さを意味し、表面うねりWaはうねり曲線の算術平均高さを意味する。粗さ曲線及びうねり曲線の各々は、短辺方向における保護層90の断面曲線から得られる。
以上のように、本実施の形態に従うセンサ素子101においては、保護層90の表面において、表面粗さRaは8μm以下であり、表面うねりWaは6μm以上である。すなわち、保護層90の表面において、表面粗さRaがある程度小さく、かつ、表面うねりWaがある程度大きい。したがって、保護層90の表面に滴下した水分は、一箇所にとどまりにくい。その結果、センサ素子101によれば、保護層90の表面に滴下した水分がセンサ素子101以外の部分に移動する可能性が高いため、被水による熱衝撃を抑制することができる。
以上、実施の形態について説明したが、本発明は、上記実施の形態に限定されるものではなく、その趣旨を逸脱しない限りにおいて、種々の変更が可能である。以下、変形例について説明する。
上記実施の形態において、センサ素子101には、第1内部空所20と、第2内部空所40とが形成されていた。すなわち、センサ素子101は、2室構造であった。しかしながら、センサ素子101は、必ずしも2室構造である必要はない。たとえば、センサ素子101は、3室構造であってもよい。
部45を省略してもよい。
また、上記実施の形態においては、保護層90の上面に関して、表面粗さRaが8μm以下であり、表面うねりWaが6μm以上であったが、保護層90の下面、左面、右面及び前面の一部又は全部においても、表面粗さRaが8μm以下であり、表面うねりWaが6μm以上であってもよい。
<6-1.実施例及び比較例>
まず、次に説明する方法により、実施例となるセンサ素子101を製造した。具体的には、まず素子本体101aを製造し、素子本体101aに保護層90を形成することによってセンサ素子101を製造した。
図7は、耐被水性試験において用いられる装置を模式的に示す図である。図7に示されるように、ディスペンサ500は、ヘッド510と、ノズル520とを含んでいる。センサ素子101は、素子用クランプ530によって保持されている。
試験結果を以下の表1にまとめる。
Claims (7)
- 被測定ガスにおける所定ガス成分の濃度の測定に用いられるセンサ素子であって、
酸素イオン伝導性を有する固体電解質層、及び、前記固体電解質層を加熱するように構成されたヒータを含む、板状の素子本体と、
前記素子本体の少なくとも一つの面上に形成された保護層とを備え、
前記保護層の表面において、表面粗さRaは8μm以下であり、表面うねりWaは6μm以上である、センサ素子。 - 前記素子本体は、平面視において、長辺及び短辺を有し、
前記表面粗さRa及び前記表面うねりWaの各々は、前記短辺方向における前記保護層の断面曲線から得られる、請求項1に記載のセンサ素子。 - 前記素子本体の短辺方向における前記保護層の中央部に対応する位置は、前記短辺方向における前記保護層の両端部の各々に対応する位置よりも盛り上がっている、請求項1又は請求項2に記載のセンサ素子。
- 前記保護層は、内側保護層と、前記内側保護層よりも外側に位置する外側保護層とを含み、
前記内側保護層及び前記外側保護層の各々は、多孔質であり、
前記外側保護層の平均気孔径は、前記内側保護層の平均気孔径よりも小さく、
前記内側保護層の気孔率は、40%以上、60%以下である、請求項1から請求項3のいずれか1項に記載のセンサ素子。 - 前記内側保護層の膜厚は、170μm以上、900μm以下である、請求項4に記載のセンサ素子。
- 前記外側保護層の気孔率は、15%以上、50%以下である、請求項4又は請求項5に記載のセンサ素子。
- 前記外側保護層の膜厚は、30μm以上、300μm以下である、請求項4から請求項6のいずれか1項に記載のセンサ素子。
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JP2016029360A (ja) * | 2014-07-18 | 2016-03-03 | トヨタ自動車株式会社 | ガスセンサ素子 |
JP2018169324A (ja) * | 2017-03-30 | 2018-11-01 | 日本碍子株式会社 | ガスセンサ素子 |
JP2020165813A (ja) * | 2019-03-29 | 2020-10-08 | 日本碍子株式会社 | ガスセンサのセンサ素子 |
JP2020165816A (ja) * | 2019-03-29 | 2020-10-08 | 日本碍子株式会社 | ガスセンサのセンサ素子 |
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DE112022001572T5 (de) | 2024-01-04 |
US20240151685A1 (en) | 2024-05-09 |
CN116964444A (zh) | 2023-10-27 |
JP7543188B2 (ja) | 2024-09-02 |
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