Heraeus Electro-nite International N.v.

Epiq Sensor-nite N.v.

Heracus Electric-nite International N.v.

Ulrich Guth

Ulrich Sch&ouml;nauer

Silvia Lenaerts

G&ouml;tz Reinhardt

Susanne Brosda

Edelbert Hafele

Klaus-Peter Sandow

Dietrich Westphal

Hartmut Erdmann

Volker Leonhard

Heidrun Koppen

Dieter Fischer

Marianne Ilgenstein

Barbara Roth

Steffen Jakobs

A porous electrode structure for a gas sensor, as well as a sensor arrangement, is provided for detecting hydrocarbons in a measured gas. The porous structure guarantees, in addition to a low impedance, a high temporal stability and reproducibility of the measurement signal. The porous electrode structure has a conductive gold framework, which contains oxide components, in particular gallium oxide.

Porous electrode structure for a gas sensor and sensor arrangement

A gas sensor is provided for measurement of oxygen and/or the air-to-fuel lambda ratio and hydrocarbons and/or carbon monoxide in gas mixtures. To reliably measure a plurality of gaseous components, the sensor is provided with a reference electrode representing a constant oxygen partial pressure, an oxygen ion-conducting solid electrolyte, and at least two measuring electrodes, the measuring electrodes and the reference electrode being mounted directly on the solid electrolyte and having electrical leads for connection and for take-away of electrical measurement signals. The solid electrolyte ( ) is constructed with a measurement gas side exposed to the gas mixture and a reference gas side separated from the gas mixture. The system of electrodes has the reference electrodes ( &Prime;) on the reference gas side and at least two measuring electrodes ( ) on the measurement gas side, and is so constructed that one of the reference electrodes ( ) is assigned to at least one measuring electrode ( ), which forms the anode of this electrode pair ( ). The pair of electrodes ( ) is adapted for the application of a voltage or a current for pumping oxygen, and the system simultaneously transmits at least two measurement signals, which correspond to different gaseous components of the gas mixture.

Gas sensor

A method of measuring oxygen and/or the air-to-fuel lambda ratio and hydrocarbons and/or carbon monoxide in gas mixtures using a gas sensor is provided. To reliably measure a plurality of gaseous components, the sensor is provided with a reference electrode representing a constant oxygen partial pressure, an oxygen ion-conducting solid electrolyte, and at least two measuring electrodes, the measuring electrodes and the reference electrode being mounted directly on the solid electrolyte and having electrical leads for connection and for take-away of electrical measurement signals. The solid electrolyte is constructed with a measurement gas side exposed to the gas mixture and a reference gas side separated from the gas mixture. The system of electrodes has the reference electrodes on the reference gas side and at least two measuring electrodes on the measurement gas side, and is so constructed that one of the reference electrodes is assigned to at least one measuring electrode, which forms the anode of this electrode pair. The pair of electrodes is adapted for the application pumping oxygen, and the system simultaneously transmits at least two measurement signals, which correspond to different gaseous components of the gas mixture.

Method of using a gas sensor

A galvanic solid electrolyte sensor for measuring gaseous anhydrides includes a ceramic solid electrolyte that has a material that conducts electrons, a measuring electrode that includes a pure or doped alkaline or alkaline earth salt and a reference electrode spatially separated from the measuring electrode and sealed off from the anhydride measuring gas by a gas-tight enclosure. The reference electrode is made of a metal material that conducts electrons. The gas-tight enclosure is made of a layer of a glass containing zirconium and lead that covers only the material of the reference electrode, with only a marginal area of this layer abutting the solid electrolyte.

Solid electrolyte sensor for measuring gaseous anhydrides

Electrode material for hydrocarbon sensors

Porous, ceramic layers, which also have a diffusion-limiting action, are as a rule manufactured by selectively adding pore formers to the ceramic sinter material. The porosity of the layer created in this way lies in the micrometer range. The known processes for manufacturing layers of this type are intended for application to planar substrates. Suitability for spherical surfaces and a porosity of the layer in the nanometer range is provided herein by an oxide ceramic powder having a BET specific surface area in the range of about 5 to 50 m.sup.2 /g and having a mean primary particle size of about 20 to 450 nm. The powder is first pretreated at a temperature of about 800.degree. C. to 1150.degree. C. and then mixed with untreated, oxide ceramic powder. The mixture is then applied to a high temperature-stable base, and burned-in (fired) at a temperatures of about 1000.degree. C. to 1350.degree. C. Optionally, instead of the thermally pretreated oxide ceramic powder, a recrystallized glass powder can be used. The firing temperature range in this case, however, is about 850.degree. C. to 1000.degree. C.

Process for manufacturing ceramic, diffusion-limiting layers and use of

An electrode material is provided for electrochemical sensors, particularly for sensors detecting combustible gases. For these types of applications, perovskite electrode materials are known which, however, by modification of their oxygen stoichiometry, have a considerable charge carrier mobility. These defects are the causes for an additional, catalytic activity with oxidation processes at electrodes. The measurement of hydrocarbons from combustible gases is thus distorted with electrode materials of this type. These disadvantages are overcome by making such electrode materials from mixed oxides with non-perovskite crystalline structures, which have chemical compositions of one or more of the following general formulas: (A/D).sub.3-y B.sub.x C.sub.5-x O.sub.12.+-..delta., D.sub.1-y B.sub.1-x C.sub.x O.sub.4.+-..delta., D.sub.2-y B.sub.8-x C.sub.x O.sub.16.+-..delta., D.sub.2-y B.sub.1+x C.sub.1-x O.sub.5.+-..delta., or D.sub.2-y B.sub.x C.sub.2-x O.sub.7.+-..delta., wherein A and D are respectively sub-stoichiometrically used cations of the lanthanide series and the alkaline earth metal group, A/D means a cation selected from A, D and mixture thereof, B is a multivalent ion, and C is a redox-stable ion.

Electrode material

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Greifswald, Germany

Ulrich Guth