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Oxygen sensor and manufacturing method of sensor element

Imported: 24 Feb '17 | Published: 06 Jan '04

Hiroshi Isomura, Takayoshi Atsumi, Koji Shiono, Masamine Takagi

USPTO - Utility Patents

Abstract

The oxygen sensor of the present invention has excellent durability capable of effectively preventing contamination with lead or the like for a detection electrode even in low temperature exhaust gases, and having stable response over a long period of time. The contamination preventive layer provided in the sensor device comprises composite powders having coarse powders covered therearound with fine powders, and hollows not filled with fine powders are scattered in gaps among the composite powders. Both the coarse and fine powders comprise ceramic powders. Further, it is particularly preferred that the ceramic powders are powders of a titania powder having a peak at 1 m or less and a composite ceramic powder containing alumina such as spinel having a peak at 10 m or more. The contamination preventive layer can be formed by coating a slurry containing ceramic powders of different specific surface areas, an organic binder and a solvent such as methanol on the surface of the electrode protection layer followed by drying.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.

1(

a) is a scanning type electron microscopic photograph in the magnification factor of 100× for a contamination preventive layer formed to a sensor device of an Experimental Example 20. (b) is a scanning type electron microscopic photograph at a magnifying factor of 3500× that magnifies a central portion for (a).

FIG. 2 is a graph illustrating that the oxygen sensor of Example 2 is excellent in durability.

FIG. 3 is a front elevational view illustrating an appearance after forming an electrode protection layer of the sensor device.

FIG. 4 is a front elevational view illustrating an appearance after forming the contamination preventive layer.

FIG. 5 is a cross sectional view of a sensor device in which a detection electrode or the like is formed on the outer surface and a reference electrode is formed on the inner surface of a solid electrolyte substrate of the sensor device.

FIG. 6 is a schematic view for a burner measuring apparatus for evaluating the durability.

Claims

1. An oxygen sensor comprising:

2. The oxygen sensor according to claim 1, wherein the titania powder is an anatase type titania powder.

3. The oxygen sensor according to claim 1 or 2, wherein the ceramic powder other than titania is a powder of a composite oxide containing aluminum atoms.

4. The oxygen sensor according to claim 1 or 2, wherein the grain size distribution of primary particles of the titania powder has a peak from 0.003 to 0.5 m and the grain size distribution of primary particles of the ceramic powder oxides other than titania has a peak from 15 to 50 m.

5. A method of manufacturing a sensor device including a detection electrode, an electrode protection layer formed on the surface of the detection electrode and a contamination preventive layer formed on the surface of the electrode protection layer, comprising:

6. A method of manufacturing a sensor device including a detection electrode, an electrode protection layer formed on the surface of the detection electrode and a contamination preventive layer formed on the surface of the electrode protection layer, comprising:

7. A method of manufacturing a sensor device including a detection electrode, an electrode protection layer formed on the surface of the detection electrode and a contamination preventive layer formed on the surface of the electrode protection layer, comprising: