Gas sensor element and method of manufacturing gas sensor element

Abstract

A gas sensor element and related manufacturing method are disclosed comprising the steps of preparing a gas sensor element body, including a solid electrolyte body having both sides formed with a measuring-gas-side electrode and a reference-gas-side electrode, respectively, and a diffusion resistance layer formed the solid electrolyte body so as to surround the measuring-gas-side electrode, coating a trap layer forming slurry, having an aluminum ion content equal to or less than 1.2 wt %, on at least an outer sidewall of the difflusion resistance layer of the gas sensor element body, and baking a coated layer of the trap layer forming slurry to form a trap layer on the outer sidewall of the diffusion resistance layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view showing a gas sensor element of a first embodiment according to the present invention with a diffusion resistance layer formed with a trap layer.

FIG. 2 is a basic sequence of steps of manufacturing the gas sensor element shown in FIG. 1.

FIG. 3 is a graph showing fluctuation in sensor output produced by the gas sensor element shown in FIG. 1.

FIG. 4 is a graph showing the relationship between an aluminum ion content of a trap layer forming slurry and a sensor output of a gas sensor element manufactured in Example.

FIG. 5 is a cross sectional view showing a gas sensor element of a second embodiment according to the present invention with a diffusion resistance layer formed with a trap layer.

Claims

1. A method of manufacturing a gas sensor element, the method comprising the steps of: preparing a gas sensor element body including a solid electrolyte body having oxygen ion conductivity, a measuring-gas-side electrode formed on one surface of the solid electrolyte body, a reference-gas-side electrode formed on the other surface of the solid electrolyte body, a diffusion resistance layer formed on the one surface of the solid electrolyte body so as to surround the measuring-gas-side electrode and available to permeate measuring gas to the measuring-gas-side electrode; andforming a trap layer on at least an outer sidewall of the diffusion resistance layer;wherein the trap layer forming step comprises:coating a trap layer forming slurry, having an aluminum ion content equal to or less than 1.2 wt %, on at least the outer sidewall of the diffusion resistance layer to is form a coated layer; andbaking the coated layer to form the trap layer on at least the outer sidewall of the diffusion resistance layer.

2. The method of manufacturing the gas sensor element according to claim 1, wherein: the trap layer forming slurry has the aluminum ion content equal to or less than 0.48 wt %.

3. The method of manufacturing the gas sensor element according to claim 1, wherein: the trap layer forming slurry includes an aluminum sol.

4. A method of manufacturing a gas sensor element, the method comprising the steps of: preparing a gas sensor element body including a solid electrolyte body having oxygen ion conductivity, a measuring-gas-side electrode formed on one surface of the solid electrolyte body, a reference-gas-side electrode formed on the other surface of the solid electrolyte body, a diffusion resistance layer formed on the one surface of the solid electrolyte body so as to surround the measuring-gas-side electrode and available to permeate measuring gas to the measuring-gas-side electrode;coating a trap layer forming slurry, containing porous alumina ceramic particles having an aluminum ion content equal to or less than 1.2 wt %, on at least the outer sidewall of the diffusion resistance layer to form a coated layer;baking the coated layer to form the trap layer on at least the outer sidewall of the diffusion resistance layer; andstacking a reference gas chamber forming layer, having a reference gas chamber facing the reference-gas-side electrode, on the gas sensor element body.

5. The method of manufacturing the gas sensor element according to claim 4, wherein: the trap layer forming slurry has the aluminum ion content equal to or less than 0.48 wt %.

6. The method of manufacturing the gas sensor element according to claim 4, wherein: the trap layer forming slurry includes an aluminum sol.

7. A gas sensor element comprising: a solid electrolyte body having oxygen ion conductivity;a measuring-gas-side electrode formed on one surface of the solid electrolyte body;a reference-gas-side electrode formed on the other surface of the solid electrolyte body;a diffusion resistance layer formed on the one surface of the solid electrolyte body so as to surround the measuring-gas-side electrode and available to permeate measuring gas to the measuring-gas-side electrode; anda trap layer formed on an outer sidewall of the diffusion resistance layer;wherein with the gas sensor element subjected to an endurance test conducted under an atmosphere at a temperature of 950° C. for 100 hours, the gas sensor element has a sensor output deviation rate less than 5%; andwherein the sensor output deviation rate takes a value obtained by the relationship expressed by (B−A)/B (%) where A represents a sensor output on a stage before the endurance test and B represents a sensor output on a stage after the endurance test.

8. The gas sensor element according to claim 7, wherein: the sensor output deviation rate remains in a value less than 2%.

9. A gas sensor element comprising: a solid electrolyte body having oxygen ion conductivity;a measuring-gas-side electrode formed on one surface of the solid electrolyte body;a reference-gas-side electrode formed on the other surface of the solid electrolyte body;a diffusion resistance layer formed on the one surface of the solid electrolyte body so as to surround the measuring-gas-side electrode and available to permeate measuring gas to the measuring-gas-side electrode; anda trap layer formed on an outer sidewall of the diffusion resistance layer using a trap layer forming slurry composed of porous alumina ceramic particles containing an aluminum ion content equal to or less than 1.2 wt %;wherein the gas sensor element has a sensor output deviation rate less than 5%; andwherein the sensor output deviation rate takes a value obtained by the relationship expressed by (B-A)/B (%) where A represents a sensor output on a stage before the endurance test and B represents a sensor output on a stage after the endurance test.

10. The gas sensor element according to claim 9, wherein: the sensor output deviation rate remains in a value less than 2%.

11. The gas sensor element according to claim 9, wherein: the solid electrolyte body and the diffusion resistance layer are flat in structure to form a stack type sensor element body.

12. The gas sensor element according to claim 9, wherein: the solid electrolyte body includes a bottomed, cylindrical solid electrolyte body;the reference-gas-side electrode is formed on an inner cylindrical wall of the cylindrical solid electrolyte body;the measuring-gas-side electrode is formed on an outer cylindrical wall of the cylindrical solid electrolyte body; andthe diffusion resistance layer is formed on the measuring-gas-side electrode.