CN111505084B - Sensing element and preparation method thereof - Google Patents
Sensing element and preparation method thereof Download PDFInfo
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- CN111505084B CN111505084B CN201910098220.5A CN201910098220A CN111505084B CN 111505084 B CN111505084 B CN 111505084B CN 201910098220 A CN201910098220 A CN 201910098220A CN 111505084 B CN111505084 B CN 111505084B
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- 238000002360 preparation method Methods 0.000 title abstract description 34
- 230000003197 catalytic effect Effects 0.000 claims abstract description 267
- 239000000919 ceramic Substances 0.000 claims abstract description 256
- 239000000758 substrate Substances 0.000 claims abstract description 158
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 88
- 239000011159 matrix material Substances 0.000 claims abstract description 69
- 239000011148 porous material Substances 0.000 claims abstract description 21
- 239000001301 oxygen Substances 0.000 claims description 91
- 229910052760 oxygen Inorganic materials 0.000 claims description 91
- 239000007784 solid electrolyte Substances 0.000 claims description 90
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 83
- 239000002002 slurry Substances 0.000 claims description 34
- 238000000034 method Methods 0.000 claims description 31
- 239000012266 salt solution Substances 0.000 claims description 21
- 239000000047 product Substances 0.000 claims description 19
- 238000004519 manufacturing process Methods 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 16
- 238000005245 sintering Methods 0.000 claims description 16
- 239000011265 semifinished product Substances 0.000 claims description 15
- 239000002253 acid Substances 0.000 claims description 11
- 230000032683 aging Effects 0.000 claims description 9
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 8
- 238000000498 ball milling Methods 0.000 claims description 7
- 239000002003 electrode paste Substances 0.000 claims description 7
- 239000000843 powder Substances 0.000 claims description 7
- 239000000243 solution Substances 0.000 claims description 7
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 239000013078 crystal Substances 0.000 claims description 6
- 239000003792 electrolyte Substances 0.000 claims description 6
- 229910052574 oxide ceramic Inorganic materials 0.000 claims description 6
- 239000011224 oxide ceramic Substances 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000011230 binding agent Substances 0.000 claims description 4
- 229910052763 palladium Inorganic materials 0.000 claims description 4
- 239000004014 plasticizer Substances 0.000 claims description 4
- 238000010345 tape casting Methods 0.000 claims description 4
- VYRZVNZTWPARPF-UHFFFAOYSA-M N.[Cl-].[Rh+3] Chemical compound N.[Cl-].[Rh+3] VYRZVNZTWPARPF-UHFFFAOYSA-M 0.000 claims description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 3
- WEHPWQFUPSIJQG-UHFFFAOYSA-H [Na].Cl[Rh](Cl)(Cl)(Cl)(Cl)Cl Chemical compound [Na].Cl[Rh](Cl)(Cl)(Cl)(Cl)Cl WEHPWQFUPSIJQG-UHFFFAOYSA-H 0.000 claims description 3
- 239000006255 coating slurry Substances 0.000 claims description 3
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 claims description 3
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 claims description 3
- NWAHZABTSDUXMJ-UHFFFAOYSA-N platinum(2+);dinitrate Chemical compound [Pt+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O NWAHZABTSDUXMJ-UHFFFAOYSA-N 0.000 claims description 3
- AAIMUHANAAXZIF-UHFFFAOYSA-L platinum(2+);sulfite Chemical compound [Pt+2].[O-]S([O-])=O AAIMUHANAAXZIF-UHFFFAOYSA-L 0.000 claims description 3
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical compound [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 claims description 3
- SONJTKJMTWTJCT-UHFFFAOYSA-K rhodium(iii) chloride Chemical compound [Cl-].[Cl-].[Cl-].[Rh+3] SONJTKJMTWTJCT-UHFFFAOYSA-K 0.000 claims description 3
- 238000000151 deposition Methods 0.000 claims description 2
- 239000011541 reaction mixture Substances 0.000 claims 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 72
- 229910052697 platinum Inorganic materials 0.000 description 33
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 22
- 239000000446 fuel Substances 0.000 description 17
- 229910052751 metal Inorganic materials 0.000 description 15
- 239000002184 metal Substances 0.000 description 15
- 238000012360 testing method Methods 0.000 description 15
- 239000007789 gas Substances 0.000 description 14
- 239000011241 protective layer Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 239000000203 mixture Substances 0.000 description 11
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 9
- 229910052726 zirconium Inorganic materials 0.000 description 9
- 238000010344 co-firing Methods 0.000 description 8
- -1 oxygen ions Chemical class 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 7
- 239000010410 layer Substances 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
- 238000001035 drying Methods 0.000 description 5
- 239000011267 electrode slurry Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 4
- 239000007772 electrode material Substances 0.000 description 4
- 238000009713 electroplating Methods 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 238000004806 packaging method and process Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
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- 229920006395 saturated elastomer Polymers 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
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- 239000002912 waste gas Substances 0.000 description 3
- 229910001233 yttria-stabilized zirconia Inorganic materials 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000000593 degrading effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 description 2
- 238000005538 encapsulation Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000007750 plasma spraying Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 229910052596 spinel Inorganic materials 0.000 description 2
- 239000011029 spinel Substances 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910001868 water Inorganic materials 0.000 description 2
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000000462 isostatic pressing Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 150000002739 metals Chemical group 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- GGROONUBGIWGGS-UHFFFAOYSA-N oxygen(2-);zirconium(4+);hydrate Chemical compound O.[O-2].[O-2].[Zr+4] GGROONUBGIWGGS-UHFFFAOYSA-N 0.000 description 1
- 238000012536 packaging technology Methods 0.000 description 1
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 150000005837 radical ions Chemical class 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000004901 spalling Methods 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- ZCUFMDLYAMJYST-UHFFFAOYSA-N thorium dioxide Chemical compound O=[Th]=O ZCUFMDLYAMJYST-UHFFFAOYSA-N 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
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
- G01N27/4073—Composition or fabrication of the solid electrolyte
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- C—CHEMISTRY; METALLURGY
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
- C04B35/486—Fine ceramics
- C04B35/488—Composites
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
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- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/06—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances
- C04B38/063—Preparing or treating the raw materials individually or as batches
- C04B38/0635—Compounding ingredients
- C04B38/0645—Burnable, meltable, sublimable materials
- C04B38/068—Carbonaceous materials, e.g. coal, carbon, graphite, hydrocarbons
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- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
- C04B41/51—Metallising, e.g. infiltration of sintered ceramic preforms with molten metal
- C04B41/5122—Pd or Pt
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- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
- C04B41/85—Coating or impregnation with inorganic materials
- C04B41/88—Metals
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- 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
- G01N27/4075—Composition or fabrication of the electrodes and coatings thereon, e.g. catalysts
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
- C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
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- Chemical & Material Sciences (AREA)
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- Chemical Kinetics & Catalysis (AREA)
- Molecular Biology (AREA)
- Measuring Oxygen Concentration In Cells (AREA)
Abstract
The invention discloses a sensing element and a preparation method thereof, the sensing element comprises a ceramic substrate and one or more electrodes arranged on the surface of the ceramic substrate, each electrode comprises a catalytic electrode part and a lead electrode part, the catalytic electrode part and the lead electrode part of each electrode are electrically connected, the catalytic electrode part of part or all of the electrodes comprises a catalytic electrode ceramic matrix formed on the surface of the ceramic substrate and noble metals arranged in and on the catalytic electrode ceramic matrix, the catalytic electrode ceramic matrix is porous ceramic with micro three-dimensional pore channels in and on the surface, and the noble metals are distributed in the porous ceramic in a three-dimensional network. The invention aims to provide a low-cost and high-performance sensing element, and the catalytic electrode part of the sensing element is formed by a novel ceramic catalytic electrode, so that the sensing element provided by the invention also has the characteristics of low cost and excellent catalytic performance.
Description
Technical Field
The invention relates to the field of oxygen sensors, in particular to a sensing element and a preparation method thereof.
Background
In a control system of an engine for a vehicle, which is a key technology for ensuring that the engine operates with a mixture of an optimal air-fuel ratio, an oxygen sensor for a vehicle is a key component for controlling an air-fuel ratio of the mixture of the engine, the oxygen sensor is a key component for feeding back a gas condition after oil-gas mixture combustion to an Engine Control Unit (ECU) in real time, and an engine electronic control injection system precisely controls an air-fuel ratio (a/F, mass ratio of air to gasoline) according to a signal provided by the oxygen sensor.
The three-way catalyst is the most important off-board purifying device installed in the exhaust system of automobile, and can convert harmful gases such as CO, HC and NOx discharged from the automobile exhaust into harmless carbon dioxide, water and nitrogen through oxidation and reduction. However, in order to effectively use the three-way catalyst, the air-fuel ratio must be precisely controlled so that it always approaches the stoichiometric air-fuel ratio. Therefore, in the use of a three-way catalytic converter engine, an oxygen sensor is an indispensable element. When the air-fuel ratio of the mixture deviates from the theoretical air-fuel ratio, the purifying ability of the three-way catalyst to CO, HC and NOX is reduced sharply, an oxygen sensor arranged in the exhaust pipe can detect the concentration of oxygen in the exhaust gas, a feedback signal is sent to the ECU, and the ECU controls the increase and decrease of the fuel injection quantity of the fuel injector, so that the air-fuel ratio of the mixture can be controlled near the theoretical value, the engine can work in the optimal air-fuel mixture ratio, namely, the optimal air-fuel ratio state, and conditions are created for the waste gas purification of the three-way catalyst of the engine.
The oxygen sensor is a measuring element for measuring the oxygen potential in an automobile exhaust pipeline by utilizing a ceramic sensing element, and calculating the corresponding oxygen concentration according to a chemical balance principle so as to monitor and control the combustion air-fuel ratio and ensure the product quality and the standard of tail gas emission. The oxygen sensor is generally divided into a tubular oxygen sensor and a sheet oxygen sensor, and the tubular zirconium dioxide oxygen sensor is taken as an example to explain the working principle:
The tubular zirconia oxygen sensor consists of a zirconia tube (referred to as a zirconium tube for short), a platinum electrode, a protective sleeve and the like, wherein the zirconium tube and the platinum electrode form a sensing element (refer to figure 1), the zirconium tube is a solid electrolyte element made of zirconia containing a small amount of yttrium, and the inner side and the outer side of the zirconium tube are coated with a layer of platinum to form an inner platinum electrode and an outer platinum electrode. The inner side of the zirconium tube is communicated with the atmosphere, and the outer side of the zirconium tube is contacted with the exhaust gas. At the use temperature, oxygen generates electron-withdrawing oxidation-reduction reaction in a three-phase interface area formed by the oxygen, the platinum electrode and the zirconia, oxygen in the zirconium tube is changed into oxygen ions under the catalysis of the platinum electrode, oxygen ions outside the zirconium tube are changed into oxygen molecules under the catalysis of the platinum electrode, and potential difference exists between the inner electrode and the outer electrode due to the fact that the oxygen ion concentration of the inner side and the outer side of the zirconium tube is high (generally, the oxygen concentration in the atmosphere is high, and the oxygen concentration in the outer side is low). The outside electrode is exposed to the exhaust gas, so that the oxygen ion concentration changes according to different actual working conditions, and the inside electrode is reference air, so that the oxygen ion concentration is unchanged. When the air-fuel ratio of the engine is lean, the oxygen concentration in the exhaust gas is relatively high, the difference of the oxygen concentration between the inner electrode and the outer electrode is small, namely the potential difference is small, and the output voltage signal of the oxygen sensor is close to 0V. On the contrary, when the air-fuel ratio is rich, the oxygen concentration in the exhaust gas is relatively low, the difference in oxygen concentration between the inner and outer electrodes is large, that is, the potential difference is large, and the output voltage of the sensor is close to 1V. An exemplary response curve of the oxygen sensor is shown in fig. 2, in which lambda is an index of the air excess ratio, i.e., the ratio of the actual air-fuel ratio to the stoichiometric air-fuel ratio, used to determine the lean-rich degree of the mixture.
With continued reference to fig. 1, the electrodes in the sensing element of the oxygen sensor include a catalytic electrode portion and a lead electrode portion, as viewed in terms of their function during use. The catalytic electrode part is mainly used for catalyzing oxidation-reduction reaction and generating an electric signal, and the lead electrode part is mainly used for guiding out the generated electric signal. The preparation of electrodes for the sensor element of an oxygen sensor, wherein the key point of the technology is how to provide electrodes of a certain thickness (e.g. the platinum electrodes mentioned above) on a ceramic substrate, has also earlier been a method of coating electrode layers directly on a ceramic (which may be the zirconia mentioned above) substrate, but has not been adopted because of the extreme susceptibility of the electrode layers to spalling. The common technical proposal adopted at present is the co-firing technology of the electrode and the solid electrolyte ceramic and the electrode electroplating technology. The electroplating electrode technology refers to the invention patent application publication CN200310114168.7 and the like, and the electroplating electrode has the advantages that the prepared electrode layer is very thin, the consumption is small, more three-phase interfaces and good activity are realized, the problem of large consumption of noble metal of the cofiring electrode is effectively solved, but the combination reliability between the electrode material and the matrix is relatively poor, and the electrode material is easy to peel off; and the electroplating process is complex and is easy to pollute the environment.
The co-firing technology of the electrode and the solid electrolyte ceramic refers to application number 200410064804.4 and the like, and the co-firing electrode has the advantages that the bonding reliability between an electrode layer and a matrix is good, the problem that the electrode layer is easy to peel off when being directly coated is solved, and the co-firing electrode has the advantages that the thickness is 6-10 microns because the electrode adopts a thick film, platinum particles are micron or sub-nanometer noble metal particles, the electrode material is co-fired at the temperature of 1400-1550 ℃, the low-temperature catalytic activity of the electrode is poor, and meanwhile, a three-phase interface has certain loss, so that more noble metal consumption is needed under the condition of obtaining the same catalytic activity, and the cost is high.
Disclosure of Invention
The invention aims to provide a low-cost and high-performance sensing element, and the catalytic electrode part of the sensing element is formed by a novel ceramic catalytic electrode, so that the sensing element provided by the invention also has the characteristics of low cost and excellent catalytic performance.
Another object of the present invention is to provide a method for manufacturing a sensor element, which has simple process operation, good bonding property of electrode material and ceramic matrix, less noble metal consumption, and good catalytic activity. Is particularly suitable for the technical field of oxygen sensors.
The technical scheme of the invention is as follows: the sensing element comprises a ceramic substrate and one or more electrodes arranged on the surface of the ceramic substrate, wherein each electrode comprises a catalytic electrode part and a lead electrode part, the catalytic electrode part and the lead electrode part of each electrode are electrically connected, the catalytic electrode part of part or all of the electrodes comprises a catalytic electrode ceramic matrix formed on the surface of the ceramic substrate and noble metals arranged in and on the catalytic electrode ceramic matrix, the catalytic electrode ceramic matrix is porous ceramic with micro three-dimensional pore channels in and on the surface of the catalytic electrode ceramic matrix, and the noble metals are distributed in a three-dimensional network in and on the porous ceramic.
Preferably, the noble metal is distributed on the surface of the micro three-dimensional pore canal of the catalytic electrode ceramic matrix in a crystal grain form, so that the noble metal forms a three-dimensional network structure in and on the catalytic electrode ceramic matrix, and electric signals can be conveniently transmitted.
Preferably, the ceramic substrate is tubular and has an inner cavity extending inward from the bottom surface;
the electrode comprises an outer electrode arranged on the outer surface of the ceramic substrate and an inner electrode arranged on the wall of the inner cavity;
The external electrode comprises an external catalytic electrode part and an external lead electrode part, wherein the external catalytic electrode part is arranged at the tail end of the outer side surface of the ceramic substrate in a surrounding mode, and the external lead electrode part is arranged at the outer side of the ceramic substrate and extends to the bottom surface of the ceramic substrate and is electrically connected with the external catalytic electrode part;
the inner electrode comprises an inner catalytic electrode part which is arranged at the tail end of the wall part of the inner cavity in a surrounding mode, and an inner lead electrode part which is arranged on the wall part of the inner cavity, extends to the bottom surface of the ceramic substrate and is electrically connected with the inner catalytic electrode part.
Preferably, the ceramic substrate is sheet-shaped, and the electrode comprises an external electrode arranged on the upper surface of the ceramic substrate and an internal electrode arranged on the lower surface of the ceramic substrate;
the external electrode comprises an external catalytic electrode part and an external lead electrode part electrically connected with the external catalytic electrode;
the inner electrode comprises an inner catalytic electrode part and an inner lead electrode part electrically connected with the inner catalytic electrode, and the inner catalytic electrode part and the inner lead electrode part of the inner electrode are cofiring electrodes which are fired at one time at high temperature.
Preferably, the porosity of the catalytic electrode ceramic matrix is between 20% and 80%, and the thickness of the catalytic electrode ceramic matrix is between 10 and 1000 microns.
The technical scheme of the invention also comprises an oxygen sensor which comprises the sensing element.
The technical scheme of the invention also comprises a preparation method of the sensing element, which comprises the following steps:
Providing a solid electrolyte substrate green body; providing a slurry forming a catalytic electrode ceramic matrix; providing a cofiring electrode paste;
coating slurry for forming a catalytic electrode ceramic substrate on a region of the surface of a solid electrolyte substrate green body, which is required to prepare a catalytic electrode part, coating cofiring slurry on a region of the surface of the solid electrolyte substrate green body, which is required to prepare a lead electrode part, and then co-sintering to obtain a solid electrolyte ceramic substrate, and a catalytic electrode ceramic substrate and a lead electrode part which are arranged on the solid electrolyte ceramic substrate, wherein the catalytic electrode ceramic substrate is porous ceramic with electrolyte characteristics and micro three-dimensional pore channels in the interior and the surface;
uploading noble metal salt solution into a catalytic electrode ceramic matrix, and then baking and decomposing to obtain a semi-finished product of the sensing element;
And (3) baking and aging the semi-finished product of the sensing element at a high temperature of 600-1000 ℃.
Preferably, the noble metal salt solution is one or a non-reactive mixture of a plurality of chloroplatinic acid, platinum nitrate, platinum sulfite, rhodium chloride, ammonium chlororhodium, sodium hexachlororhodium, rhodium nitrate, palladium chloride, palladium nitrate and palladium sulfate solution.
Preferably, the slurry for forming the catalytic electrode ceramic matrix is prepared by the following method:
ball-milling the powder of the solid oxide ceramic with an alcohol solution to prepare slurry, adding a pore-forming agent, a binder and a plasticizer into the slurry, and continuing ball-milling to finally obtain the slurry for forming the catalytic electrode ceramic matrix.
Preferably, the noble metal salt solution is uploaded into the catalytic electrode ceramic matrix, and then, when the catalytic electrode ceramic matrix is baked and decomposed, the noble metal salt in the noble metal salt solution is decomposed into noble metal decomposition products, and the noble metal decomposition products are deposited in micro three-dimensional pore channels of the catalytic electrode ceramic matrix to obtain a semi-finished product of the sensing element;
After the semi-finished product of the sensing element is baked and aged at the high temperature of 600-1000 ℃, noble metal salt in the noble metal salt solution is decomposed at high temperature to form noble metal grains, the noble metal grains are distributed on the surface of a micro three-dimensional pore canal of the catalytic electrode ceramic matrix, and adjacent noble metal grains are mutually fused and connected, so that the noble metal forms a three-dimensional network structure inside and on the surface of the catalytic electrode ceramic matrix, and electric signals are conveniently transmitted.
Preferably, the solid electrolyte substrate green body is provided as an unsintered solid electrolyte substrate green body,
Simultaneously sintering the green solid electrolyte substrate and the slurry for forming the catalytic electrode ceramic matrix applied to the surface of the green solid electrolyte substrate,
The sintering is performed at a temperature of 1400 ℃ to 1550 ℃.
Preferably, the solid electrolyte base green body is tubular, and the tubular solid electrolyte green body is obtained by the following method:
preparing a tubular solid electrolyte substrate green body;
And (3) baking and curing the prepared tubular solid electrolyte substrate blank at a high temperature of 800-1300 ℃.
Preferably, the solid electrolyte substrate green body is sheet-shaped, and the sheet-shaped solid electrolyte substrate green body is obtained by the following method:
is prepared by a tape casting process.
THE ADVANTAGES OF THE PRESENT INVENTION
1. The catalytic electrode part of the sensing element provided by the invention is formed by the novel ceramic catalytic electrode, the novel ceramic catalytic electrode has a structure that noble metals form three-dimensional net-shaped distribution which is communicated with each other in the porous solid electrolyte ceramic matrix and on the surface, and the structure greatly increases the number of three-phase interfaces among the noble metals, the porous solid electrolyte ceramic and oxygen, so that the novel ceramic catalytic electrode also has excellent catalytic capability under the condition that a small amount of noble metals can be used, and the production cost is reduced to a great extent, so that the sensing element provided by the invention also has the characteristics of low cost and excellent catalytic performance.
2. Compared with a co-fired electrode, the catalytic electrode part of the sensing element provided by the invention has better catalytic activity because noble metal is not sintered at high temperature.
3. According to the preparation method of the sensing element, the catalytic electrode ceramic matrix of the novel ceramic catalytic electrode is prepared on unsintered solid electrolyte and then sintered together, so that the combination height of the catalytic electrode ceramic matrix and the solid electrolyte substrate is high, and the sensing element provided by the invention has no problem of falling of a catalytic electrode layer.
4. Compared with experimental data of a sensing element manufactured by taking a cofiring electrode as a catalytic electrode part, the sensing element provided by the invention has the advantages that under the condition of greatly reducing the consumption of noble metal, the voltage rising speed is higher, namely the catalytic performance is more excellent.
Drawings
FIG. 1 is a schematic view of the external and internal structures of a sensing element of a tube oxygen sensor of the prior art.
FIG. 2 is a typical response curve of an oxygen sensor.
Fig. 3 is a schematic diagram of a process for forming a novel ceramic catalytic electrode according to a first embodiment of the present invention.
Fig. 4 is a novel ceramic catalytic electrode provided in accordance with a first embodiment of the present invention.
Fig. 5 is a graph showing the voltage rise of the sample according to the first embodiment of the present invention.
Fig. 6 is a reference diagram of a voltage jump curve when the value of N is 21 according to the third embodiment of the present invention.
Fig. 7 is a diagram showing a process for manufacturing a tubular sensor element having excellent properties according to a fourth embodiment of the present invention.
Detailed Description
The technical scheme of the invention is described in detail below with reference to fig. 1-7 and examples, wherein: 1. a ceramic substrate; 2. an external electrode; 21. an external catalytic electrode section; 22. an external lead electrode portion; 3. an inner electrode; 31. an internal catalytic electrode section; 32. an inner lead electrode portion; 4. novel ceramic catalytic electrodes; 41. a catalytic electrode ceramic substrate; 42. noble metals.
It should be noted that the term "sintering" as used throughout this invention refers to the transformation of a powdery material into a dense body, which is a conventional process for producing ceramics, and the sintering temperature is 1400 ℃ -1550 ℃. The term "cofiring" as used throughout this disclosure refers to cofiring. The invention relates to a co-fired electrode, which is an electrode formed by co-firing an electrode and a solid electrolyte ceramic substrate in the prior art, and a specific preparation method of the co-fired electrode can be referred to as a patent application document with the number 200410064804.4.
Novel ceramic catalytic electrode and preparation method thereof
In a first embodiment, the present invention discloses a novel ceramic catalytic electrode 4 and a method for preparing the same, the novel ceramic catalytic electrode 4 being useful as an electrode for a sensing element of an oxygen sensor.
Referring to fig. 3 and 4, the novel ceramic catalytic electrode 4 includes a catalytic electrode ceramic substrate 41 and a noble metal 42 disposed inside and on the surface of the catalytic electrode ceramic substrate, wherein the catalytic electrode ceramic substrate 41 is a honeycomb porous ceramic having micro-stereoscopic channels inside and on the surface, and the catalytic electrode ceramic substrate has a solid electrolyte characteristic, i.e. has oxygen ion conductivity. The noble metal is distributed in the porous ceramic in a three-dimensional net shape, specifically, the noble metal is distributed on the surface of the micro three-dimensional pore canal of the porous solid electrolyte ceramic in a crystal grain form, and adjacent crystal grains are mutually fused and connected in the process that the noble metal crystal grains are heat treated, so that the noble metal forms a three-dimensional net structure which is mutually communicated on the surface of the micro three-dimensional pore canal of the porous ceramic, and electric signals are conveniently transmitted.
The three-phase noble metal structure is formed on the surface of the tiny three-dimensional pore canal of the porous ceramic with the solid electrolyte characteristic (the porous solid electrolyte ceramic is used for short in the whole text), and the three-phase interfaces among the noble metal, the porous solid electrolyte ceramic and oxygen are greatly increased, so that the novel ceramic catalytic electrode has excellent catalytic capability under the condition of using a small amount of noble metal, and the production cost is greatly reduced. Specific experimental data can be found hereinafter.
The noble metal is preferably a platinum group noble metal. Further, the noble metal may be one or more of platinum, palladium and rhodium.
According to the novel ceramic catalytic electrode, the ceramic substrate of the catalytic electrode is porous solid electrolyte ceramic, the porosity is between 20% and 80%, and due to the high porosity, noble metals are distributed on the surface of the micro three-dimensional pore canal of the porous solid electrolyte ceramic in a crystal grain form, so that a three-dimensional network structure which is conducted mutually is formed, and electric signals can be conveniently transmitted. Further, the porosity is preferably between 40% and 60%.
The catalytic electrode ceramic matrix of the novel ceramic catalytic electrode is solid oxide ceramic with electric conductivity to oxygen ions in a certain temperature range (150-930 ℃). Preferably, the solid oxide ceramic is yttria-doped zirconia, calcia-doped zirconia or yttria-doped thoria. The catalytic electrode ceramic substrate has a thickness of 10-1000 microns, with a preferred thickness of 100-300 microns.
The novel ceramic catalytic electrode of the present invention is formed on the surface of a ceramic substrate 1 having solid electrolyte characteristics. The ceramic substrate 1 is an oxide solid electrolyte well known to those skilled in the art, and is a solid electrolyte part that can be used as an oxygen sensor, and has conductivity to oxygen ions, specifically yttria stabilized zirconia ceramic. The ceramic substrate 1 has a dense structure and cannot absorb liquid into the interior of the ceramic substrate.
On the surface of the ceramic substrate 1, lead electrodes can be added, the novel ceramic catalytic electrode is mainly used for catalyzing oxidation-reduction reaction and generating electric signals, and the lead electrodes mainly serve to lead out the generated electric signals.
The novel ceramic catalytic electrode of the present invention may be used as the whole electrode of the sensor element of the oxygen sensor, or may be used as only a part of the electrode of the sensor element of the oxygen sensor, for example, the novel ceramic catalytic electrode may be used only as a catalytic electrode portion of the electrode of the sensor element of the oxygen sensor, and the lead electrode portion of the electrode of the sensor element of the oxygen sensor may be made of another material (for example, a cofiring electrode).
As shown in fig. 2 and 3, the first embodiment of the present invention further provides a preparation method of the novel ceramic catalytic electrode, which specifically includes the following steps:
(1) Providing a solid electrolyte substrate green body; a slurry is provided that forms a catalytic electrode ceramic matrix.
A. The solid electrolyte substrate green body and the preparation process thereof are prior art, for example, the solid electrolyte substrate green body can be an unsintered zirconia solid electrolyte substrate green body, and the preparation process thereof can be specifically referred to as the following steps:
Step 1: Y2O3 having a purity of 99.9% is mixed with ZrO2 having a purity of not less than 99%, wherein the Y2O3 content is 5mol%. The mixture was thoroughly mixed and calcined at 1300 ℃ for 2 hours.
Step 2: ball milling the calcined mixture until D80 is less than 2.5 microns.
Step 3: spherical particles with an average particle diameter of 70 μm were obtained by spray drying.
Step 4: and (3) obtaining a U-shaped green body through dry bag type isostatic pressing, and grinding on an automatic running water grinding machine to obtain a final shape.
Step 5: the prepared green body is baked and reinforced at 1000-1200 ℃.
B. The slurry for forming the catalytic electrode ceramic matrix comprises a powder of solid oxide ceramic (for example, yttria-doped zirconia powder), an alcohol solution, a pore-forming agent (for example, carbon powder), a binder (for example, polyvinyl butyral) and a plasticizer (for example, dibutyl phthalate). The proportion of the pore-forming agent can influence the porosity of the catalytic electrode ceramic matrix, and generally the proportion of the pore-forming agent is in direct proportion to the porosity of the catalytic electrode ceramic matrix, namely the pore-forming agent has high porosity when the proportion is high, and the pore-forming agent has low porosity when the proportion is low. The preparation method of the slurry for forming the catalytic electrode ceramic matrix is a conventional technology for preparing porous ceramics, and the preparation method can be as follows:
Ball milling the powder of the solid oxide ceramic and an alcohol solution for 4 hours to prepare slurry, then continuously adding a pore-forming agent, a binder and a plasticizer into the slurry, and continuously ball milling for 16 hours to obtain the slurry for forming the catalytic electrode ceramic matrix.
(2) The slurry for forming the catalytic electrode ceramic substrate was applied to the surface of the green solid electrolyte substrate and then co-sintered to obtain the catalytic electrode ceramic substrate having a thickness of 10 to 1000 μm formed on the surface of the solid electrolyte ceramic substrate, as shown in fig. 3. The catalytic electrode ceramic matrix is porous ceramic with electrolyte characteristics and micro three-dimensional pore channels in the interior and the surface.
The slurry for forming the catalytic electrode ceramic matrix is sintered together with the green solid electrolyte substrate, so that the catalytic electrode ceramic matrix and the solid electrolyte ceramic substrate have good combination property and high combination fastness.
(3) And uploading the noble metal salt solution into a catalytic electrode ceramic substrate, and then baking and decomposing to obtain a semi-finished product of the catalytic electrode.
A. The noble metal salt solution is an aqueous solution of a compound formed by noble metal ions and acid radical ions, and can be, for example, a non-reactive mixture of one or more of chloroplatinic acid, platinum nitrate, platinum sulfite, rhodium chloride, ammonium chlororhodium, sodium hexachlororhodium, rhodium nitrate, palladium chloride, palladium nitrate and palladium sulfate solution, preferably a saturated aqueous solution of chloroplatinic acid.
B. the step of uploading the noble metal salt solution into the catalytic electrode ceramic substrate means that after the catalytic electrode ceramic substrate contacts the noble metal salt solution, the noble metal salt in the noble metal salt solution is adsorbed into the catalytic electrode ceramic substrate by capillary action. And then baking and decomposing the catalytic electrode ceramic matrix adsorbed with the noble metal salt to decompose the noble metal salt into noble metal decomposed products, and depositing the noble metal decomposed products in micro three-dimensional pore channels of the catalytic electrode ceramic matrix.
(4) And (3) carrying out high-temperature baking aging treatment on the semi-finished product of the catalytic electrode at 600-1000 ℃ to obtain the ceramic catalytic electrode disclosed by the invention, as shown in fig. 4.
When the high-temperature baking aging treatment is carried out at 600-1000 ℃, the decomposition products of the noble metal are further decomposed to form noble metal grains, the noble metal grains are distributed on the surface of the micro three-dimensional pore canal of the catalytic electrode ceramic matrix, and adjacent noble metal grains are mutually fused and connected, so that the noble metal grains form a three-dimensional network structure which is mutually communicated inside and on the surface of the catalytic electrode ceramic matrix, and electric signals are conveniently transmitted.
Sensing element and preparation method thereof
In a second embodiment, the present invention discloses a sensing element that can be used as a sensing element of an oxygen sensor, and a method of manufacturing the same.
The sensor element includes a ceramic substrate 1 having a solid electrolyte characteristic, and one or more electrodes provided on a surface of the ceramic substrate 1, each electrode including a catalytic electrode portion and a lead electrode portion, the catalytic electrode portion of each electrode being connected to the lead electrode portion. The catalytic electrode portion of some or all of the electrodes is constituted by the novel ceramic catalytic electrode provided by the first embodiment of the present invention. Since the specific structure and the preparation method of the novel ceramic catalytic electrode have been described in detail, the description thereof will not be repeated herein, and reference is made to the related description in the first embodiment.
It should be noted that the catalytic electrode portion of the single electrode may be entirely constituted by the novel ceramic catalytic electrode, or a part of the catalytic electrode portion of the single electrode may be constituted by the novel ceramic catalytic electrode, and another part may be constituted by another electrode (such as a cofiring electrode).
The electrodes of the sensing element provided in this embodiment (including a catalytic electrode portion and a lead electrode portion, where the catalytic electrode portion is mainly used for catalyzing oxidation-reduction reaction and generating an electrical signal, and the lead electrode portion is mainly used for guiding out the generated electrical signal), may all be composed of a novel ceramic catalytic electrode, or may be composed of a novel ceramic catalytic electrode and an electrode commonly used in the prior art, for example, the catalytic electrode portion is composed of a novel ceramic catalytic electrode, and the lead electrode portion is composed of a cofiring electrode.
The sensor element provided in this embodiment may be used in various existing concentration difference type tubular oxygen sensors or sheet type oxygen sensors. A specific structure of a sensing element for a tubular oxygen sensor may be referred to as fig. 1, including a ceramic substrate having a tubular shape with an inner cavity formed to extend inward from a bottom surface, and an inner electrode including an outer electrode provided on an outer surface of the ceramic substrate and an inner electrode provided on a wall of the inner cavity; the external electrode comprises an external catalytic electrode part and an external lead electrode part, wherein the external catalytic electrode part is arranged at the tail end of the outer side surface of the ceramic substrate in a surrounding mode, and the external lead electrode part is arranged at the outer side of the ceramic substrate and extends to the bottom surface of the ceramic substrate and is electrically connected with the external catalytic electrode part; the inner electrode comprises an inner catalytic electrode part which is arranged at the tail end of the wall part of the inner cavity in a surrounding mode, and an inner lead electrode part which is arranged on the wall part of the inner cavity, extends to the bottom surface of the ceramic substrate and is electrically connected with the inner catalytic electrode part.
In a specific embodiment of the sensing element for a tubular oxygen sensor, the outer catalytic electrode portion is comprised of the novel ceramic catalytic electrode and the outer lead electrode portion and the inner electrode of the outer electrode are comprised of co-fired electrodes.
In another specific embodiment of a sensing element for a tubular oxygen sensor, the inner catalytic electrode portion is comprised of the novel ceramic catalytic electrode and the inner lead electrode portion and the outer electrode are comprised of a co-fired electrode.
In yet another specific embodiment of a sensing element for a tubular oxygen sensor, the outer catalytic electrode portion and the inner catalytic electrode portion are comprised of the novel ceramic catalytic electrode, and the outer lead electrode portion and the inner lead electrode portion are comprised of a co-fired electrode.
In one embodiment of a sensing element for a chip oxygen sensor, a ceramic substrate of the sensing element is in a shape of a chip, and electrodes of the sensing element include an outer electrode disposed on an upper surface of the ceramic substrate and an inner electrode disposed on a lower surface of the ceramic substrate; the external electrode comprises an external catalytic electrode part and an external lead electrode part electrically connected with the external catalytic electrode; the inner electrode comprises an inner catalytic electrode part and an inner lead electrode part electrically connected with the inner catalytic electrode, and the inner catalytic electrode and the inner lead electrode are co-fired electrodes which are fired at a high temperature.
In a specific embodiment of the sensing element for a chip oxygen sensor, the outer catalytic electrode part is composed of the novel ceramic catalytic electrode, and the outer lead electrode part and the inner electrode of the outer electrode are composed of co-fired electrodes.
On the basis of the preparation method of the novel ceramic catalytic electrode provided by the first embodiment of the invention, the embodiment also provides a preparation method of the sensing element, which comprises the following specific steps:
(1) Providing a solid electrolyte substrate green body; providing a slurry forming a catalytic electrode ceramic matrix; a slurry for forming a co-fired electrode slurry (hereinafter referred to simply as co-fired electrode slurry) is provided.
When the solid electrolyte base green body is tubular, the method of producing the solid electrolyte base green body can be referred to the method of producing the solid electrolyte base green body provided in the first embodiment. When the solid electrolyte substrate green body is sheet-shaped, the solid electrolyte substrate green body can be prepared by a tape casting forming process, wherein the tape casting forming process is a ceramic product forming method in the prior art, is a mature forming method capable of obtaining high-quality and ultra-thin ceramic chips at present, and is widely applied to the production of advanced ceramics such as monolithic capacitor ceramic chips, thick films, thin film circuit substrates and the like.
The co-fired electrode paste is in the prior art, and specifically can be high-temperature co-fired platinum paste, and the manufacturing method thereof can refer to the application document with the patent application number 200410064804.4.
(2) And coating the slurry forming the catalytic electrode ceramic substrate on the surface of the solid electrolyte substrate green body in the area where the catalytic electrode part is required to be prepared, coating the cofiring slurry on the surface of the solid electrolyte substrate green body in the area where the lead electrode part is required to be prepared, and then sintering the solid electrolyte substrate green body, the slurry forming the catalytic electrode ceramic substrate on the surface of the green body and the cofiring slurry together to obtain the solid electrolyte ceramic substrate, and the catalytic electrode ceramic substrate and the lead electrode part which are arranged on the solid electrolyte ceramic substrate, wherein the catalytic electrode ceramic substrate is porous ceramic with electrolyte characteristics and micro three-dimensional pore channels in the interior and the surface.
(3) And uploading the noble metal salt solution into a catalytic electrode ceramic matrix, and then drying and decomposing to obtain a semi-finished product of the sensing element.
(4) And (3) carrying out high-temperature baking ageing treatment on the semi-finished product of the sensing element at 600-1000 ℃ to obtain the sensing element provided by the embodiment.
The inventor of the present invention has found through a great deal of experiments that an oxygen sensor using a co-fired electrode as a catalytic electrode is a comparative example, and an oxygen sensor having the sensing element provided in this embodiment can have more excellent catalytic performance with less noble metal.
The co-fired electrode in the prior art is used as a catalytic electrode to manufacture a sensing element, the oxygen sensor obtained after encapsulation is used as a comparative example, and the specific sensing element is prepared by the following steps:
(1) Providing a solid electrolyte substrate green body; a cofiring electrode paste is provided.
(2) The cofiring paste is applied to the surface of the solid electrolyte substrate green body in the areas where the catalytic electrode portions and the lead electrode portions are to be prepared, and then the product is sintered.
The specific parameters of the comparative example are: baking and reinforcing the solid electrolyte substrate green body at 1100 ℃, wherein the sintering temperature is 1450 ℃; the cofiring electrode was used as both the catalytic electrode portion and the lead electrode portion, and the total amount of platinum converted to the catalytic electrode portion was 0.006 g.
The three oxygen sensors of sample 1, sample 2 and sample 3 were obtained by preparing a sensor element using the preparation method of a sensor element provided in this example and packaging the sensor element. Wherein:
Sample 1: baking and reinforcing the solid electrolyte substrate green body at 800 ℃, wherein the sintering temperature is 1450 ℃; the powder of the slurry for forming the catalytic electrode ceramic matrix is yttria stabilized zirconia, and the particle size distribution d10=0.1 micron, d50=5 micron and d90=7 micron; the noble metal salt solution uses saturated aqueous solution of chloroplatinic acid, and the platinum loading amount of the novel ceramic catalytic electrode obtained according to conversion of the chloroplatinic acid is 0.001 g; the catalytic electrode ceramic matrix deposited with noble metal salt is subjected to high-temperature baking aging treatment at 9000 ℃.
Sample 2: baking and reinforcing the solid electrolyte substrate green body at 1200 ℃; the platinum loading of the novel ceramic catalytic electrode obtained according to the conversion of chloroplatinic acid is 0.0013 g; other parameters and steps were the same as for sample 1.
Sample 3: baking and reinforcing the solid electrolyte substrate green body at 1000 ℃; the powder of the slurry for forming the catalytic electrode ceramic matrix was still yttria stabilized zirconia with a particle size distribution d10=0.34 microns, d50=0.53 microns, d90=1.02 microns; the noble metal salt solution still uses saturated aqueous solution of chloroplatinic acid, and the platinum loading amount of the novel ceramic catalytic electrode obtained according to conversion of the chloroplatinic acid is 0.001 g; other parameters and steps were the same as for sample 1.
To compare the differences between the comparative examples and the samples, the test was compared by a certain test. Test conditions: and packaging the product in a test fixture, and checking an oxygen sensor induction signal through waste gas in test equipment.
The product was heated first and the time for the voltage to reach 900mV under the same conditions was recorded, please refer to the following table data and the voltage rise graph of FIG. 5.
| Platinum dosage (g) | Time to reach 900 mV(s) | |
| Comparative example | 0.006 | 32.2 |
| Sample 1 | 0.001 | 24.8 |
| Sample 2 | 0.0013 | 22.4 |
| Sample 3 | 0.001 | 20.3 |
TABLE 1
As can be seen from table 1 and fig. 5, compared with the cofiring electrode, the sensing element manufactured by the novel ceramic catalytic electrode according to the first embodiment of the present invention achieves a faster voltage rising speed, i.e., exhibits more excellent low-temperature catalytic performance, while greatly reducing the noble metal usage.
Novel tubular sensing element, preparation method thereof and oxygen sensor with sensing element
In a third embodiment, the invention discloses a novel tubular sensing element, a preparation method thereof and an oxygen sensor with the sensing element. The overall structure of the novel tubular sensing element is the same as that of the tubular sensing element in the prior art, please refer to fig. 1, and the novel tubular sensing element comprises a tubular ceramic substrate 1 with solid electrolyte characteristics, an external electrode 2 and an internal electrode 3, wherein the ceramic substrate 1 is provided with an inner cavity formed by extending inwards from the bottom surface; the external electrode 2 is arranged on the outer surface of the ceramic substrate 1, and comprises an external catalytic electrode part 21 which is arranged around the tail end of the outer surface of the ceramic substrate, and an external lead electrode part 22 which is arranged on the outer side of the ceramic substrate and extends to the bottom surface of the ceramic substrate and is electrically connected with the external catalytic electrode part; the inner electrode 3 is disposed on the wall of the inner cavity, and includes an inner catalytic electrode portion 31 disposed around the end of the wall portion of the inner cavity, and an inner lead electrode portion 32 disposed on the wall portion of the inner cavity, extending to the bottom surface of the ceramic substrate, and electrically connected to the inner catalytic electrode portion.
The difference between the novel tubular sensing element provided in this embodiment and the tubular sensing element in the prior art is the structure, material and preparation method of the external catalytic electrode portion. The external catalytic electrode part of the tubular sensing element in the prior art generally uses a co-fired electrode, and the external catalytic electrode part of the novel tubular sensing element provided by the embodiment is the novel ceramic catalytic electrode provided by the first embodiment of the invention, and has the characteristics of small noble metal consumption, excellent catalytic performance and high bonding fastness between the electrode and the substrate.
Since the specific structure and the preparation method of the novel ceramic catalytic electrode have been described in detail, the description thereof will not be repeated herein, and reference is made to the related description in the first embodiment.
The external lead electrode portion and the internal electrode of the external electrode of the novel tubular sensor element provided in this embodiment may be formed of a cofiring electrode or may be formed of the novel ceramic catalytic electrode provided in the first embodiment.
Further, in order to prevent the outer electrode of the sensing member of the oxygen sensor, i.e., the electrode on the side contacting the exhaust gas, from being corroded by the exhaust gas discharged from the engine and thus degrading the catalytic performance of the noble metal (typically, platinum metal) the novel tubular sensing member further comprises a protective layer covering the surface of the outer electrode. The material of the protective layer is well known to those skilled in the art, and is composed of ceramics having a solid electrolyte characteristic, and specifically may be alumina, magnesia-alumina spinel, zirconia-alumina composite material, or the like. The protective layer can be prepared by means of ion spraying or secondary sintering.
On the basis of the preparation method of the sensing element provided by the second embodiment of the present invention, the present embodiment provides a preparation method of the novel tubular sensing element, which specifically includes the following steps:
(1) Providing a tubular solid electrolyte substrate green body having an inner cavity extending inwardly from a bottom surface; providing a slurry forming a catalytic electrode ceramic matrix; a cofiring electrode paste is provided.
(2) The method comprises the steps of coating slurry for forming a catalytic electrode ceramic substrate on an area, needing to prepare an external catalytic electrode part, of the outer surface of a solid electrolyte substrate green body, coating cofiring slurry on an area, needing to prepare a lead electrode part, of the outer surface of the solid electrolyte substrate green body and an area, needing to prepare an internal electrode, of the wall of an inner cavity, and then co-sintering to obtain the solid electrolyte ceramic substrate, the catalytic electrode ceramic substrate and the external lead electrode part which are arranged on the outer surface of the solid electrolyte ceramic substrate, and the internal electrode on the wall of the inner cavity of the ceramic substrate, wherein the catalytic electrode ceramic substrate is porous ceramic with electrolyte characteristics and tiny three-dimensional pore channels in the inner and the surface.
(3) And uploading the noble metal salt solution into the catalytic electrode ceramic matrix, and then drying to obtain a semi-finished product of the sensing element.
(4) And (3) carrying out high-temperature baking ageing treatment on the semi-finished product of the sensing element at 600-1000 ℃ to obtain the sensing element provided by the embodiment.
The embodiment also provides an oxygen sensor obtained by packaging the sensing element provided in the embodiment. The inventor of the present invention compares the oxygen sensor manufactured by the co-fired electrode with the oxygen sensor provided in the present embodiment through a large number of experiments in terms of the amount of platinum metal, the stability of the oxygen sensor, the voltage jump frequency of the oxygen sensor, and the like, and further demonstrates the advantages of the oxygen sensor provided in the present embodiment.
Test 1: testing of the amount of platinum metal used and the stability of the oxygen sensor.
Comparative example:
The inner and outer electrodes of the sensing element are prepared according to the traditional process of the cofiring electrode, the same packaging technology is adopted to prepare the oxygen sensor samples 1 to 6, the cofiring electrode is used for the inner and outer catalytic electrode parts of the 6 sample oxygen sensor, and the metal platinum consumption of the inner and outer catalytic electrode parts is 0.01g. The 6 sample oxygen sensors were tested at around 350 degrees as follows:
The lambda value of the simulated exhaust gas was switched between 0.97 and 1.03. The output of the sensor is referred to as high voltage when lambda=0.97, and low voltage when lambda=1.03. The time for the voltage value to jump from 600mV to 300mV is called T2, and the time for the voltage value to jump from 300mV to 600mV is called T4. The test data for 6 products are shown in the following table:
| Comparative example | High voltage (mV) | Low voltage (mV) | T2(mS) | T4(mS) |
| Sample 1 | 867.4 | 52.87 | 259.2 | 126.9 |
| Sample 2 | 837.64 | 61.65 | 352.2 | 84.2 |
| Sample 3 | 853.36 | 60.73 | 246.5 | 97.3 |
| Sample 4 | 875.11 | 52.34 | 160.7 | 128.1 |
| Sample 5 | 857.26 | 66.53 | 268.4 | 89.1 |
| Sample 6 | 844.44 | 52.49 | 355.5 | 102.1 |
| Average value of | 855.9 | 57.8 | 273.8 | 104.6 |
| Value of the most person | 875.1 | 66.5 | 355.5 | 128.1 |
| Minimum value | 837.6 | 52.3 | 160.7 | 84.2 |
TABLE 2
It can be seen from the above table that the dispersion difference between the high voltage and T2 is relatively large. The high voltage dispersion is large, namely the signal characteristic dispersion of the product is large, and the emission control is easy to deviate. The large T2 dispersion, namely the unstable sensitivity of the product, can also cause deviation of emission control.
Examples:
the inner electrode of the sensing element is still prepared by adopting the process of the cofiring electrode, the outer electrode is prepared by adopting the preparation method of the novel ceramic catalytic electrode provided in the first embodiment, samples 1 to 6 are obtained according to the same encapsulation mode of the comparative example, the dosage of the metal platinum of the inner catalytic electrode part of the 6 oxygen sensors is 0.01g, the loading amount of the metal platinum of the outer catalytic electrode part is 0.002g, and the thickness of the outer catalytic electrode part is 0.3mm and the length is 5mm.
The test was performed under the same test conditions and test methods as the comparative examples, and the following data were obtained:
| Examples | High voltage (mV) | Low voltage (mV) | T2(mS) | T4(mS) |
TABLE 3 Table 3
As can be seen from comparison of tables 2 and 3, the high voltage in Table 3 is slightly higher overall, the low voltage is slightly lower overall, the T2 consistency is better, and the T4 value is slightly larger. In general, compared with the oxygen sensor manufactured by the cofiring electrode, the consumption of the metal platinum of the external catalytic electrode part of the oxygen sensor provided by the embodiment is only 1/5 of the consumption of the metal platinum when the cofiring electrode is used as the external catalytic electrode part, but the uniformity of the product performance is better, namely the stability is better.
Test 2: and testing the use amount of the metal platinum and the voltage jump frequency of the oxygen sensor.
Comparative example:
According to the design scheme that the same metal platinum dosage is used for the internal catalytic electrode part, and the metal platinum dosage of the external catalytic electrode part (co-fired electrode) is singly changed, a sensing element is manufactured, and is packaged into an oxygen sensor to be manufactured into 9 samples, and the voltage jump frequency is tested, and the testing method is as follows:
when the oxygen sensor outputs high voltage, lambda=0.97 is output, a signal for opening the extra air valve is output, the extra air valve on the device starts to open, the lambda value is switched from 0.97 to 1.03, and the voltage output by the oxygen sensor starts to drop. When the voltage output by the oxygen sensor reaches 450mV, a signal for closing the extra air valve is immediately given, at the moment, the voltage value still continues to drop for a period of time due to the hysteresis of control to start rising, when the voltage rises to 450mV, a signal for opening the extra air valve is given again, and the voltage value still continues to rise for a period of time to start falling due to the hysteresis of control, so that the voltage continuously oscillates up and down at 450 mV. The number of transitions of the sensor within a specified time is recorded as the value N (for a more clear explanation of the voltage transition process, reference is made to fig. 6, which is a voltage transition graph when n=21). Test data for 9 samples are shown in the following table:
| Comparative example | Internal catalytic electrode usage (g) | External catalytic electrode dosage (g) | N value |
| Sample 1 | 0.01 | 0.006 | 28 |
| Sample 2 | 0.01 | 0.008 | 26 |
| Sample 3 | 0.01 | 0.01 | 25 |
| Sample 4 | 0.01 | 0.012 | 23 |
| Sample 5 | 0.01 | 0.014 | 21 |
| Sample 6 | 0.01 | 0.016 | 20 |
| Sample 7 | 0.01 | 0.018 | 19 |
| Sample 8 | 0.01 | 0.02 | 16 |
| Sample 9 | 0.01 | 0.022 | 15 |
TABLE 4 Table 4
Examples:
the same design scheme as that of the comparative example was adopted, namely, the same amount of metal platinum was used according to the inner catalytic electrode part, the amount of metal platinum of the outer catalytic electrode part (novel ceramic catalytic electrode provided in the first embodiment) was singly changed, a sensor element was fabricated, and an oxygen sensor was packaged to make 9 samples. The thickness of the catalytic electrode ceramic matrix of the novel ceramic catalytic electrode of the sample is 0.3mm, the length is 5mm or 10mm, and the amount of the noble metal platinum is calculated by weighing the amount of the loaded saturated chloroplatinic acid.
Test data for 9 samples using the same test method as the comparative example are shown in the following table:
TABLE 5
It can be seen from tables 4 and 5 that the smaller the N value, the more the amount of platinum metal used. As can be seen from comparing table 4 and table 5, the same or even lower voltage jump frequency can be achieved by comparing the metal platinum amount of the external catalytic electrode portion of the embodiment with the metal platinum amount of the external catalytic electrode portion of the embodiment, that is, the same product performance can be achieved, and the metal platinum amount of the novel ceramic catalytic electrode provided by the first embodiment of the invention only needs to be one tenth of the metal platinum amount of the co-fired electrode.
Tubular sensing element with excellent performance, preparation method of sensing element and oxygen sensor with sensing element
In a fourth embodiment, the invention discloses a tubular sensing element with excellent performance, a preparation method of the sensing element and an oxygen sensor with the sensing element.
The novel tubular sensing element disclosed in the third embodiment, because the novel ceramic catalytic electrode provided by the invention is adopted as the external catalytic electrode part, the protective layer of the sensing element cannot be prepared by adopting a cofiring process with other parts of the sensing element, and can only be prepared by adopting a plasma spraying or secondary sintering mode. But the production efficiency of plasma spraying is lower, the spraying equipment is more expensive and consumes more energy, and the production cost of a single product is higher. The protective layer is prepared by a secondary sintering method, so that the complexity of the preparation process is increased, the binding force between the protective layer and a substrate is not high, the protective layer is easy to fall off, and the problem that an external electrode is polluted by waste gas is caused.
Therefore, in the fourth embodiment, the tubular sensing element with excellent performance disclosed by the invention has the advantages that the novel ceramic catalytic electrode provided by the invention is adopted in the inner catalytic electrode part, and the co-firing electrode is adopted in the outer electrode part, so that when the protective layer is required to be added, the protective layer can be prepared by adopting a co-firing process with other parts of the sensing element, the product process is simplified, and meanwhile, the bonding firmness of the protective layer and the solid electrolyte ceramic substrate is improved. Referring to fig. 1 for the overall structure of the tubular sensor element with excellent performance, the tubular sensor element comprises a tubular ceramic substrate 1 with solid electrolyte characteristics, an external electrode 2 and an internal electrode 3, wherein the ceramic substrate 1 has an inner cavity formed by extending inwards from the bottom surface; the external electrode 2 is arranged on the outer surface of the ceramic substrate 1, and comprises an external catalytic electrode part 21 which is arranged around the tail end of the outer surface of the ceramic substrate, and an external lead electrode part 22 which is arranged on the outer side of the ceramic substrate and extends to the bottom surface of the ceramic substrate and is electrically connected with the external catalytic electrode part; the inner electrode 3 is disposed on the wall of the inner cavity, and includes an inner catalytic electrode portion 31 disposed around the end of the wall portion of the inner cavity, and an inner lead electrode portion 32 disposed on the wall portion of the inner cavity, extending to the bottom surface of the ceramic substrate, and electrically connected to the inner catalytic electrode portion. Wherein, the inner catalytic electrode part adopts the novel ceramic catalytic electrode provided by the invention, and the outer electrode adopts a cofiring electrode.
Because the novel ceramic catalytic electrode provided by the invention is used in the internal catalytic electrode part of the sensing element provided by the embodiment, the novel ceramic catalytic electrode has the characteristics of small noble metal consumption, excellent catalytic performance and high bonding fastness between the electrode and the substrate. Since the specific structure and the preparation method of the novel ceramic catalytic electrode have been described in detail, the description thereof will not be repeated herein, and reference is made to the related description in the first embodiment.
The inner lead electrode portion of the inner electrode of the tubular sensor element with excellent performance provided in this embodiment may be formed of a co-fired electrode or may be formed of a novel ceramic catalytic electrode provided in the present invention.
Also, in order to prevent the outer electrode of the sensing member of the oxygen sensor, i.e., the electrode on the side contacting the exhaust gas, from being corroded by the exhaust gas discharged from the engine and thus degrading the catalytic performance of the noble metal (typically, platinum metal) the novel tubular sensing member further includes a protective layer covering the surface of the outer electrode. The material of the protective layer is well known to those skilled in the art, and may be specifically alumina, magnesia alumina spinel, zirconia alumina composite material, or the like. The protective layer may be prepared by co-firing with other components of the sensing element.
On the basis of the preparation method of the sensing element provided by the second embodiment of the present invention, this embodiment also discloses a preparation method of the tubular sensing element with excellent performance, which includes:
providing a tubular solid electrolyte substrate green body having an inner cavity extending inwardly from a bottom surface; providing a cofiring electrode paste; providing a slurry forming a catalytic electrode ceramic matrix;
Applying the co-fired electrode paste to an outer electrode region of an outer surface of the solid electrolyte base green body and an inner lead electrode portion region on a wall of an inner cavity, applying a paste forming a catalytic electrode ceramic matrix to a bottom of the inner cavity of the solid electrolyte base green body, and then performing a drying process;
Preparing a protective layer on the surface of the cofiring electrode slurry coated on the outer surface of the substrate green body, and then drying;
the solid electrolyte substrate green compact, the co-fired electrode slurry coated on the outer surface of the solid electrolyte substrate green compact, the co-fired electrode slurry on the wall of the inner cavity of the solid electrolyte substrate green compact and the slurry forming the catalytic electrode ceramic matrix at the bottom of the inner cavity of the dried solid electrolyte substrate green compact are sintered together to obtain a solid electrolyte ceramic substrate, an outer electrode arranged on the outer surface of the solid electrolyte ceramic substrate, and a catalytic electrode ceramic matrix at the inner lead electrode part and the bottom of the inner cavity on the wall of the inner cavity of the ceramic substrate, wherein the catalytic electrode ceramic matrix is porous ceramic with electrolyte characteristics and tiny three-dimensional pore channels on the inner and the surface;
Uploading noble metal salt solution into a catalytic electrode ceramic matrix, and then drying to obtain a semi-finished product of the sensing element;
And (3) baking and aging the semi-finished product of the sensing element at a high temperature of 600-1000 ℃.
The present embodiment also provides an oxygen sensor obtained by packaging the tubular sensor element having excellent performance provided in the present embodiment. The oxygen sensor has the same metal platinum dosage and catalytic performance as the oxygen sensor provided by the third embodiment, and meanwhile, the preparation process is simpler, and the preparation cost is lower.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the invention, but rather is intended to cover any equivalents of the structures or equivalent processes disclosed herein or in the alternative, which may be employed directly or indirectly in other related arts.
Claims (12)
1. A sensor element comprising a ceramic substrate (1), and one or more electrodes arranged on the surface of the ceramic substrate (1), each electrode comprising a catalytic electrode portion and a lead electrode portion, the catalytic electrode portion and the lead electrode portion of each electrode being electrically connected, characterized in that:
The catalytic electrode part of part or all of the electrodes comprises a catalytic electrode ceramic matrix (41) formed on the surface of the ceramic substrate (1) and noble metals arranged in and on the catalytic electrode ceramic matrix (41), wherein the catalytic electrode ceramic matrix (41) is porous ceramic with micro three-dimensional pore channels in and on the surface, and the noble metals are distributed in a three-dimensional network in and on the porous ceramic;
The noble metal is distributed on the surface of the micro three-dimensional pore canal of the catalytic electrode ceramic matrix (41) in a crystal grain form, so that the noble metal forms a three-dimensional network structure in and on the catalytic electrode ceramic matrix (41), and electric signals can be conveniently transmitted.
2. The sensing element of claim 1, wherein: the ceramic substrate (1) is tubular and is provided with an inner cavity formed by extending inwards from the bottom surface;
the electrode comprises an outer electrode arranged on the outer surface of the ceramic substrate (1) and an inner electrode arranged on the wall of the inner cavity;
the external electrode comprises an external catalytic electrode part and an external lead electrode part, wherein the external catalytic electrode part is arranged around the tail end of the outer side surface of the ceramic substrate (1), and the external lead electrode part is arranged outside the ceramic substrate (1) and extends to the bottom surface of the ceramic substrate (1) and is electrically connected with the external catalytic electrode part;
the inner electrode comprises an inner catalytic electrode part which is arranged at the tail end of the wall part of the inner cavity in a surrounding mode, and an inner lead electrode part which is arranged on the wall part of the inner cavity, extends to the bottom surface of the ceramic substrate (1) and is electrically connected with the inner catalytic electrode part.
3. The sensing element of claim 1, wherein: the ceramic substrate (1) is sheet-shaped, and the electrode comprises an external electrode arranged on the upper surface of the ceramic substrate (1) and an internal electrode arranged on the lower surface of the ceramic substrate (1);
the external electrode comprises an external catalytic electrode part and an external lead electrode part electrically connected with the external catalytic electrode;
the inner electrode comprises an inner catalytic electrode part and an inner lead electrode part electrically connected with the inner catalytic electrode, and the inner catalytic electrode part and the inner lead electrode part of the inner electrode are cofiring electrodes which are fired at one time at high temperature.
4. The sensing element of claim 1, wherein: the porosity of the catalytic electrode ceramic matrix (41) is 20-80%, and the thickness of the catalytic electrode ceramic matrix (41) is 10-1000 microns.
5. An oxygen sensor, characterized in that: comprising a sensor element according to any of claims 1-4.
6. A method of manufacturing a sensor element according to any one of claims 1 to 4, comprising:
providing a solid electrolyte substrate green body; providing a slurry forming a catalytic electrode ceramic matrix (41); providing a cofiring electrode paste;
Coating slurry for forming a catalytic electrode ceramic substrate (41) on a region of the surface of a solid electrolyte substrate green body, which is required to prepare a catalytic electrode part, coating cofiring slurry on a region of the surface of the solid electrolyte substrate green body, which is required to prepare a lead electrode part, and then co-sintering to obtain the solid electrolyte ceramic substrate (1), and the catalytic electrode ceramic substrate (41) and the lead electrode part which are arranged on the solid electrolyte ceramic substrate (1), wherein the catalytic electrode ceramic substrate (41) is porous ceramic with electrolyte characteristics and micro three-dimensional pore channels in the interior and the surface;
Uploading noble metal salt solution into a catalytic electrode ceramic matrix (41), and then baking and decomposing to obtain a semi-finished product of the sensing element;
And (3) baking and aging the semi-finished product of the sensing element at a high temperature of 600-1000 ℃.
7. The method of manufacturing a sensor element of claim 6, wherein: the noble metal salt solution is one or a non-reaction mixture of a plurality of chloroplatinic acid, platinum nitrate, platinum sulfite, rhodium chloride, ammonium chlororhodium, sodium hexachlororhodium, rhodium nitrate, palladium chloride, palladium nitrate and palladium sulfate solution.
8. The method of manufacturing a sensor element of claim 6, wherein: the slurry for forming the catalytic electrode ceramic matrix (41) is prepared by the following method:
Ball-milling the powder of the solid oxide ceramic and an alcohol solution to prepare slurry, adding a pore-forming agent, a binder and a plasticizer into the slurry, and continuing ball-milling to finally obtain the slurry for forming the catalytic electrode ceramic matrix (41).
9. The method of manufacturing a sensor element of claim 6, wherein:
Uploading a noble metal salt solution into the catalytic electrode ceramic matrix (41), and then decomposing the noble metal salt in the noble metal salt solution into a noble metal decomposed product when baking and decomposing the noble metal salt solution, and depositing the noble metal decomposed product in a micro three-dimensional pore canal of the catalytic electrode ceramic matrix (41) to obtain a semi-finished product of the sensing element;
After the semi-finished sensing element is subjected to high-temperature baking aging treatment at 600-1000 ℃, noble metal salt in the noble metal salt solution is decomposed at high temperature to form noble metal grains, the noble metal grains are distributed on the surface of a micro three-dimensional pore canal of the catalytic electrode ceramic substrate (41), and adjacent noble metal grains are mutually fused and connected, so that the noble metal forms a three-dimensional network structure inside and on the surface of the catalytic electrode ceramic substrate (41), and electric signals are conveniently transmitted.
10. The method of manufacturing a sensor element of claim 6, wherein:
The solid electrolyte substrate green body is provided as an unsintered solid electrolyte substrate green body,
Simultaneously sintering the green solid electrolyte substrate and the slurry for forming the catalytic electrode ceramic matrix (41) applied to the surface of the green solid electrolyte substrate at the time of sintering,
The sintering is performed at a temperature of 1400 ℃ to 1550 ℃.
11. The method of manufacturing a sensor element of claim 6, wherein:
the solid electrolyte substrate green body is tubular, and is obtained by the following method:
Preparing a solid electrolyte substrate green body;
And (3) baking and curing the prepared solid electrolyte substrate green body at a high temperature of 800-1300 ℃.
12. The method of manufacturing a sensor element of claim 6, wherein:
the solid electrolyte substrate green body is sheet-shaped, and is obtained by the following method:
is prepared by a tape casting process.
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