Electrolysis: processes – compositions used therein – and methods – Electrolytic material treatment – Metal or metal alloy
Reexamination Certificate
1999-08-13
2001-01-30
Tung, T. (Department: 1743)
Electrolysis: processes, compositions used therein, and methods
Electrolytic material treatment
Metal or metal alloy
C204S421000, C204S424000, C204S426000, C205S705000, C216S100000, C216S101000, C216S108000, C216S109000, C252S079200, C252S079500
Reexamination Certificate
active
06179989
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an oxygen sensor electrode and especially relates to a chemically and electrically treated oxygen sensor for use as an exhaust sensor in a vehicle.
BACKGROUND OF THE INVENTION
Exhaust sensors are conventionally used in vehicles to sense the level of oxygen in the exhaust gases. These sensors detect changes in the exhaust gas content, i.e., when the content changes from rich to lean or lean to rich in relation to the air/fuel ratio. One known type of oxygen sensor is a flat plate oxygen sensor formed of various layers of ceramic and electrolyte materials laminated and sintered together with electrical circuit and sensor traces placed between the layers in a conventional manner. A typical co-sintered flat plate sensor element is disclosed in U.S. Pat. No. 5,433,830 to Kawai et al; and commonly assigned U.S. Pat. No. 5,395,506 to Duce et al.
Numerous attempts have been made to produce improved exhaust sensors. One such sensor is disclosed in commonly assigned U.S. Pat. No. 5,384,030 to Duce et al. This patent discloses an exhaust sensor having a substrate with a dielectric material, an electrolyte material, and a transition zone disposed therebetween. Another improved sensor is disclosed in U.S. Pat. No. 5,733,504 to Paulus et al. This patent addresses lean switch point by teaching the use of a pre-equilibration zone on an exhaust gas sensor to provide a catalytic site to catalyze less reactive components of the exhaust gas prior to the gas sample reaching the sensor's exhaust side electrode.
What is needed in the art is an improved exhaust sensor having improved performance, reduced sensitivity to processing, reproducibility and potentially higher manufacturing tolerances.
SUMMARY OF THE INVENTION
The present invention comprises oxygen sensors and methods for making the same. One embodiment is an oxygen sensor, comprising: a solid electrolyte disposed between and bonded to a cathode electrode and an anode electrode to form an electrode assembly, wherein at least one of said electrodes has been chemically etched, and said electrode assembly has been electrically treated.
Another embodiment is an oxygen sensor, comprising: a solid electrolyte disposed between and bonded to a cathode electrode and an anode electrode to form an electrode assembly, wherein at least one of said electrodes has been chemically etched with a non-hydrofluoric acid solution.
One method for producing an oxygen sensor comprises the steps of: disposing anode and cathode electrodes on opposite sides of a solid electrolyte to form an electrode assembly, electrically treating the electrode assembly, and chemically etching at least one of the electrodes.
Another method for producing an oxygen sensor comprises the steps of: disposing anode and cathode electrodes on opposite sides of a solid electrolyte to form an electrode assembly and chemically etching at least one of the electrodes with a non-hydrofluoric acid solution.
These and other objects, features and advantages of the present invention will be apparent from the following brief description of the drawings, detailed description, and appended claims and drawings.
REFERENCES:
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From: Solid State Ionics ¾ North-Holland Publishing Company, entitled “Low Temperature Performance of Fluoride-Ion Treated ZrO2 Oxygen Sensor”, (1981) month unavailable pp. 631-634.
From: The American Ceramic Society, Inc., Advances in Ceramics, vol. 19, entitled “Multilayer Cermanic Devices”, by John B. Blum and W. Roger Cannon, pp. 49-68 date available.
From: The Journal of Applied Electrochemistry 3 (1973) month available, entitled “On the Influence of the Annealing Temperature and Heavy Current Treatments on the Porous Sturcture of Platinum Electrodes and on the Kinetics of the Oxygen Reaction at High Temperatures”, pp. 153-159 by S. Pizzini, M. Bianchi, P. Colombo, and S. Torchio.
From: Chemical Sensing with Solid States Devices by Marc. J. Madon and S. Roy Morrison, pp. 20-65. date unavailable.
From: Journal of Applied Electrochemistry 17 (1987) month unavailable, entitled Importance of Electrode/Zirconia Interface Morphology In High Temperature Solid Electrolyte Cells, by Turgot M. Gur, Robert A. Huggins, pp. 800-806.
Cole Carilee E.
Fournier Robert Gregory
Kennard, III Frederick Lincoln
La Barge William John
Lankheet Earl Wayne
Cichosz Vincent A.
General Motors Corporation
Tung T.
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