EP2338045A1 - Material of an electrically conductive cermet layer for electrochemical gas sensors - Google Patents
Material of an electrically conductive cermet layer for electrochemical gas sensorsInfo
- Publication number
- EP2338045A1 EP2338045A1 EP09783186A EP09783186A EP2338045A1 EP 2338045 A1 EP2338045 A1 EP 2338045A1 EP 09783186 A EP09783186 A EP 09783186A EP 09783186 A EP09783186 A EP 09783186A EP 2338045 A1 EP2338045 A1 EP 2338045A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- material according
- platinum
- gold
- alloy
- ceramic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0466—Alloys based on noble metals
-
- 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
- G01N27/4075—Composition or fabrication of the electrodes and coatings thereon, e.g. catalysts
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/06—Investigating concentration of particle suspensions
- G01N15/0656—Investigating concentration of particle suspensions using electric, e.g. electrostatic methods or magnetic methods
Definitions
- the invention relates to a material of an electrically conductive, designed as a cermet layer for electrochemical gas sensors, on a sensor element containing this and its use according to the preamble of the independent claims.
- Ceramic gas sensors which are used for the electrochemical determination of gas components in exhaust gases of internal combustion engines, are known.
- DE 39 34 586 A1, DE 42 40 267 A1 and DE 198 33 087 A1 disclose sensors whose operating principle is based, for example, on the electrochemical reduction of oxygen or oxygen-containing compounds in an exhaust gas.
- the sensor elements described include platinum metal cermet electrodes printed on substrates of yttrium stabilized zirconia.
- these platinum metal cermet electrodes have a ceramic content of 40% by volume and a metal content of about 60% by volume. Due to the ceramic additive, a good bonding of the Cernnet electrode material to the surface of the ceramic sensor is ensured; at the same time, this causes a certain basic porosity of the Cernnet
- Electrode material At the three-phase boundary between gas phase, metallic and ceramic phase, the electrochemical conversion of gas components to be detected of a gas mixture takes place.
- cermet materials are also used to produce heating elements that are integrated into electrochemical gas sensors and serve to heat them to their operating temperature.
- cermet materials are used not only for electrodes of ceramic gas sensors, which serve the electrochemical conversion of oxygen or oxygen-containing compounds, but also in electrochemical gas sensors, which operate on a resistive measuring principle.
- Such sensors can be found, for example, in DE 101 24 907 A1.
- These are used to detect soot in a fluid stream and comprise a plurality of spaced-apart measuring electrodes, which are exposed to the fluid flow to be examined. If soot is deposited between the measuring electrodes, the insulation resistance of the ceramic material is reduced
- a heating element of the sensor element makes it possible to free the electrodes or their surroundings by thermal means from deposited soot.
- the object of the present invention is to provide a cermet material for use in electrochemical gas sensors, which is a relatively has closed crystal structure and thus shows a high endurance stability or a low aging behavior.
- the material according to the invention in addition to a ceramic portion additionally serving as a sintering aid further component, which during the manufacturing process, the crystal I it growth of the metallic contained
- Advantageous sintering aids in the context of the invention are titanium dioxide or titanates.
- the effect of titanium dioxide or of the titanates used as sintering aids is particularly pronounced when mixed oxides of an element oxide with titanium dioxide are used. In this case, preference is given to using alkaline earth titanates or aluminum titanates.
- the metallic portion of the cermet material is formed by gold or by a gold alloy. It is particularly advantageous if the gold alloy contains platinum with a total weight fraction of the gold alloy of up to 15 wt.%.
- the metallic portion of the cermet material is formed by platinum or a platinum alloy. It is particularly advantageous if the platinum alloy contains rhodium and / or palladium with a total weight fraction of the platinum alloy of 5 to 10 wt.% Or iridium, ruthenium and / or cobalt with a total weight fraction of the platinum alloy of up to 5 wt.%.
- electrodes of an electrochemical gas sensor are made of such a cermet material
- the material removal due to chemical or physical processes such as evaporation or formation of volatile metal compounds, for example, in the form of carbonyls or oxides, for example, is reduced.
- the poisoning and corrosion resistance of the cermet material to reactive exhaust, oil ash or catalytic converter components increases and, moreover, the signal stability of an electrode made of this cermet material is improved.
- the material according to the invention can advantageously be used to produce electrodes of a sensor element and to form a ceramic heating element for heating the same. Other applications are in the design of electrical leads for
- Figure 1 is a plan view of a sensor element of an electrochemical
- Figure 2 is a plan view of a layer plane of the illustrated in Figure 1
- FIG. 1 shows a sensor element 10 according to a first embodiment of the present invention.
- This comprises a measuring electrode system 11, which is formed from a first and a second measuring electrode 12, 13.
- the first and the second measuring electrode 12, 13 via a first or second electrode lead 14, 15 with a first and a second contact surface 17, 18 are electrically connected.
- the electrode leads 14, 15 and the contact surfaces 17, 18 are used for electrical contacting of the measuring electrodes 12, 13.
- the measuring electrodes 12, 13 are designed, for example, as interdigitated interdigital electrodes.
- the measuring electrodes 12, 13, the leads 14, 15 and the contact surfaces 17, 18 are positioned, for example, on a ceramic, electrically insulating layer 20. This is preferably made of aluminum oxide.
- the ceramic layer 20 may be applied to a ceramic carrier body 22. Alternatively, the ceramic layer 20 in turn serve as a ceramic carrier body.
- the ceramic carrier body 22 may in turn be made of a plurality of ceramic layers, which are a planar ceramic
- Form composite layer The integrated form of the planar ceramic body of the carrier element 22 is produced, for example, by laminating together the functional films printed with ceramic films and then sintering the laminated structure in a conventional manner.
- a voltage is applied to the measuring electrodes 12, 13. Since the measuring electrodes 12, 13 are applied to the surface of the electrically insulating ceramic layer 20, substantially no current flow initially occurs between the measuring electrodes 12, 13. If a measuring gas flowing around the sensor element 10 contains electrically conductive particles, in particular carbon black, then they are deposited these on the surface of the ceramic layer 20 from. Since carbon black has a certain electrical conductivity, with sufficient loading of the surface of the ceramic layer 20 with carbon black, there is an increasing current flow between the measuring electrodes 12, 13, which correlates with the extent of the loading.
- the integral of the current flow over time can be applied to the deposited particle mass or to the current one
- Particle mass flow in particular soot mass flow, and be closed on the particle concentration in the gas mixture.
- concentration of all those particles in a gas mixture is detected, which determines the electrical conductivity of the between Measuring electrodes 12, 13 located ceramic material positively or negatively influence.
- Another possibility is to determine the increase in current flow over time and from the quotient of current flow increase and time or from the differential quotient of current flow over time on the deposited particle mass or on the current particle mass flow, in particular soot mass flow, and on the Close particle concentration in the gas mixture.
- a calculation of the particle concentration is possible on the basis of the measured values, as long as the flow velocity of the gas mixture is known.
- This or the volume flow of the gas mixture can be determined for example by means of a suitable further sensor.
- the sensor element 10 furthermore preferably comprises a heating element 40 in a layer plane 24 of the carrier body 22. This is shown in FIG.
- the sensor element 10 furthermore preferably comprises a heating element 40 in a layer plane 24 of the carrier body 22. This is shown in FIG. The
- Heating element 40 comprises a heating meander 42 designed as a resistance element, which is electrically conductively connected to second contact surfaces 46, 47 via second feed lines 44, 45.
- the supply lines 44, 45 and the second contact surfaces 46, 47 serve for the electrical contacting of the electrical resistance heating element 42.
- this is preferably embedded in a layer 48 of an electrically insulating material such as alumina.
- compartments of the present sensor element which due to operation must have a certain electrical conductivity, such as the measuring electrodes 12, 13 and the CambridgesSchetzleiterbahn 42 and their leads 14, 15, 44, 45 and their contact surfaces 17, 18, 46, 47 preferably from a Cermet material running, which is a suitable
- Sintering aid or a metal alloy contains.
- titanium dioxide or a suitable titanate is provided as a sintering aid.
- the titanium compounds mentioned cause a lower porosity of the cermet material during the manufacturing process, since the platinum-crystallite growth is greatly reduced. As a consequence, a higher aging stability of the sensor element compartments made from this cermet material can be observed, together with a marked reduction in the electrical resistance of the cermet material thus produced.
- titanium dioxide or a corresponding titanate of the general formula A x Ti x O 2 is used as a sintering aid for the production of the cermet material.
- titanium dioxide or a corresponding titanate of the general formula A x Ti x O 2 is used as a sintering aid for the production of the cermet material.
- magnesium titanate MgTiO 3 or aluminum titanate Al 2 TiO 5 having a weight fraction of titanium dioxide of, for example, up to 20% by weight, preferably up to 15% by weight, in particular up to 8% by weight, is suitable.
- the metallic portion of the cermet material is formed in particular by platinum, gold and / or palladium, however, other elements of the platinum metal group are also suitable.
- the metallic portion of the cermet material includes, for example, metal alloys, such as gold or platinum alloys.
- metal alloys such as gold or platinum alloys.
- gold alloys with a platinum content of, for example, up to 15% by weight, preferably up to 10% by weight and in particular of up to 8% by weight are used.
- Possibility of execution is to provide an electrode of platinum or a platinum alloy on the surface with a coating of gold or a gold alloy.
- gold-containing platinum alloys with a gold content of, for example, up to 10% by weight, preferably up to 5% by weight, are suitable.
- the metallic portion of the cermet material comprises a platinum alloy with a total content of rhodium and / or palladium of, for example, up to 30% by weight, preferably from 3 to 15% by weight and in particular from 5 to 10% by weight. on.
- the proportions chosen take into account that the volatility of platinum alloys is reduced by adding rhodium or palladium, so that the evaporation losses are kept low during sintering during the production of the underlying sensor element. Due to the lower material loss, a cost reduction in the production of the sensor element is realized.
- electrodes of an electrochemical gas sensor made of such a cermet material so u.a. the poisoning and corrosion resistance of the cermet material to reactive exhaust gas oil ash or exhaust catalyst components such as magnesium, calcium, phosphorus, sulfur or silicon compounds substantially.
- the cermet material described is also suitable for the formation of further compartments of ceramic electrochemical gas sensors, such as temperature measuring meanders, reference or pumping electrodes as well as their supply lines and contact surfaces.
- the described cermet material can also be used in electrochemical sensors for the determination of particles in gas mixtures.
- the described cermet material can also be used in electrochemical sensors for the determination of particles in gas mixtures.
- Sensor elements are used for the determination of gaseous components of a gas mixture.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102008042770A DE102008042770A1 (en) | 2008-10-13 | 2008-10-13 | Material of a cermet layer for electrochemical gas sensors |
PCT/EP2009/062131 WO2010043470A1 (en) | 2008-10-13 | 2009-09-18 | Material of an electrically conductive cermet layer for electrochemical gas sensors |
Publications (1)
Publication Number | Publication Date |
---|---|
EP2338045A1 true EP2338045A1 (en) | 2011-06-29 |
Family
ID=41346034
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP09783186A Withdrawn EP2338045A1 (en) | 2008-10-13 | 2009-09-18 | Material of an electrically conductive cermet layer for electrochemical gas sensors |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP2338045A1 (en) |
DE (1) | DE102008042770A1 (en) |
WO (1) | WO2010043470A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5883976B2 (en) | 2014-07-29 | 2016-03-15 | 日本碍子株式会社 | Detection electrode of gas sensor, method for producing conductive paste, and gas sensor |
DE102016217775A1 (en) | 2016-09-16 | 2018-03-22 | Robert Bosch Gmbh | Sensor element for detecting particles of a measuring gas in a measuring gas chamber |
DE102016226275A1 (en) | 2016-12-28 | 2018-06-28 | Robert Bosch Gmbh | Sensor element for detecting particles of a measuring gas in a measuring gas chamber |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2852638A1 (en) * | 1978-12-06 | 1980-06-19 | Bosch Gmbh Robert | METHOD FOR PRODUCING CERMETE ELECTRODES FOR GAS SENSORS |
US5525374A (en) * | 1992-09-17 | 1996-06-11 | Golden Technologies Company | Method for making ceramic-metal gradient composites |
US5897759A (en) * | 1996-09-11 | 1999-04-27 | Kabushiki Kaisha Riken | NOx sensor |
US20060280998A1 (en) * | 2005-05-19 | 2006-12-14 | Massachusetts Institute Of Technology | Electrode and catalytic materials |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3934586A1 (en) | 1989-10-17 | 1991-04-25 | Bosch Gmbh Robert | ELECTROCHEMICAL PROBE |
DE4240267C2 (en) | 1992-12-01 | 2003-03-20 | Bosch Gmbh Robert | Highly active electrodes for exhaust gas sensors |
US5672811A (en) * | 1994-04-21 | 1997-09-30 | Ngk Insulators, Ltd. | Method of measuring a gas component and sensing device for measuring the gas component |
DE19732601C2 (en) * | 1997-07-29 | 1999-11-04 | Heraeus Electro Nite Int | Catalytic layer system |
US5908713A (en) * | 1997-09-22 | 1999-06-01 | Siemens Westinghouse Power Corporation | Sintered electrode for solid oxide fuel cells |
DE19833087A1 (en) | 1998-07-23 | 2000-01-27 | Bosch Gmbh Robert | Gas sensor for vehicle engine; has measuring electrode comprising platinum base with sintered porous layer and noble metal covering layer, applied in galvanic bath |
DE10124907A1 (en) | 2001-05-22 | 2002-11-28 | Bosch Gmbh Robert | Electrode assembly for monitoring soot in the exhaust channel of an IC engine, or a oil heating system, has an insulation holder body with a working electrode, and a test electrode to monitor the body insulation resistance |
JP3776386B2 (en) * | 2001-09-05 | 2006-05-17 | 株式会社デンソー | Gas sensor element and gas concentration detection method |
US7153412B2 (en) * | 2001-12-28 | 2006-12-26 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Electrodes, electrochemical elements, gas sensors, and gas measurement methods |
DE102004043121A1 (en) * | 2004-09-07 | 2006-03-09 | Robert Bosch Gmbh | Sensor element for particle sensors and method for operating the same |
DE102007040726A1 (en) * | 2007-08-29 | 2009-03-05 | Robert Bosch Gmbh | gas sensor |
-
2008
- 2008-10-13 DE DE102008042770A patent/DE102008042770A1/en active Pending
-
2009
- 2009-09-18 EP EP09783186A patent/EP2338045A1/en not_active Withdrawn
- 2009-09-18 WO PCT/EP2009/062131 patent/WO2010043470A1/en active Application Filing
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2852638A1 (en) * | 1978-12-06 | 1980-06-19 | Bosch Gmbh Robert | METHOD FOR PRODUCING CERMETE ELECTRODES FOR GAS SENSORS |
US5525374A (en) * | 1992-09-17 | 1996-06-11 | Golden Technologies Company | Method for making ceramic-metal gradient composites |
US5897759A (en) * | 1996-09-11 | 1999-04-27 | Kabushiki Kaisha Riken | NOx sensor |
US20060280998A1 (en) * | 2005-05-19 | 2006-12-14 | Massachusetts Institute Of Technology | Electrode and catalytic materials |
Non-Patent Citations (1)
Title |
---|
See also references of WO2010043470A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2010043470A1 (en) | 2010-04-22 |
DE102008042770A1 (en) | 2010-04-15 |
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RIC1 | Information provided on ipc code assigned before grant |
Ipc: G01N 15/06 20060101ALN20190516BHEP Ipc: C22C 1/05 20060101ALI20190516BHEP Ipc: C22C 1/04 20060101AFI20190516BHEP Ipc: G01N 27/407 20060101ALI20190516BHEP |
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