A kind of vehicle vehicle exhaust gas sensor outer electrode protective layer and preparation method

A technology for automobile exhaust and protective layer, which is applied in the direction of instruments, scientific instruments, material electrochemical variables, etc., can solve the problems of not getting exhaust pipes, unstable idling of the engine, easy to fall off, etc., to improve the response rate and avoid lag Influence, the effect of simple process flow

Inactive Publication Date: 2015-10-21
湖北盛时杰精密机电有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, oxygen sensor poisoning is a frequent and difficult to prevent and control failure. Gasoline and engine oil contain impurities such as lead, sulfur, and phosphorus, which will greatly reduce the performance of the sensor, while dust, oil, silicon, and other components will block the sensor. The protective layer and the electrode lose the three-phase interface of the electrode reaction, which makes the response speed of the oxygen sensor slow down and the signal output is insensitive (electrode "poisoning")
Once the oxygen sensor fails, the computer ECU of the electronic fuel injection system will not be able to obtain the information of the oxygen concentration in the exhaust pipe, so it will not be able to perform feedback control on the air-fuel ratio, which will cause a sharp increase in engine fuel consumption and emissions, and engine idling instability , weak acceleration, misfire, surge or black smoke from the exhaust pipe and many other faults
[0003] In order to prevent the electrode from being invalid due to "poisoning", a protective layer is generally printed on the electrode. At present, there are two problems in the preparation of the protective layer: First, the prepared protective layer should not match well with the oxygen sensor substrate. Easy to fall off when used in harsh environments
The coefficient of thermal expansion between the protective layer prepared by this method and the base material is difficult to match, and the adhesion is not good, which makes it easy to fall off and affects the life of the oxygen sensor for vehicles.
The second is that the pore size of the prepared protective layer is micron, it is difficult to ensure that most of the harmful macromolecular substances can be filtered out; at the same time, the catalytic activity of the prepared protective layer is not enough, so that the signal response speed of the oxygen sensor is too slow
For example, the pore diameter of the porous protective layer prepared by the patent publication No. 201210245628 is 0.5-10 μm, the pores are too large, it is difficult to filter out nano-scale toxic substances, and it is easily blocked by carbon particles, which affects the life of the oxygen sensor; When preparing the protective layer in this method, the noble metal powder is directly added, so that the degree of dispersion of the added noble metal is not enough, and the catalytic activity cannot be fully exerted, resulting in that the signal response speed of the oxygen sensor cannot meet the requirements.

Method used

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  • A kind of vehicle vehicle exhaust gas sensor outer electrode protective layer and preparation method
  • A kind of vehicle vehicle exhaust gas sensor outer electrode protective layer and preparation method
  • A kind of vehicle vehicle exhaust gas sensor outer electrode protective layer and preparation method

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Experimental program
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Effect test

Embodiment 1

[0038] 1. Prepare the organic vehicle: add the binder into the solvent in a certain amount, then place it in a magnetic stirrer, set the temperature at 80°C, and the magnetron speed at 200-400r / min, until the binder is fully dissolved in the After being put into the solvent, add plasticizer, leveling agent, thixotropic agent and dispersant in proportion to configure 25g of organic vehicle. The components in the organic vehicle phase and the mass percentage of each component are shown in Table 1.

[0039] 2. Disperse 70g of yttrium-doped zirconia ceramic powder and 3.5g of chloroplatinic acid with absolute ethanol to make a premix, mix the premix evenly by ball milling, and then place it in an oven at 80°C drying.

[0040] 3. Place the dried powder in a resistance furnace for calcination at 900°C for 2 hours, and then grind the calcined powder with a mortar.

[0041] 4. Mix the ground powder in step 3, 1.5g ultrafine carbon powder and the above-mentioned 25g organic carrier, a...

Embodiment 2

[0044] 1. Prepare the organic vehicle: add the binder into the solvent in a certain amount, then place it in a magnetic stirrer, set the temperature at 80°C, and the magnetron speed at 200-400r / min, until the binder is fully dissolved in the After being put into the solvent, add plasticizer, leveling agent, thixotropic agent and dispersant in proportion to configure 25g of organic vehicle. The components in the organic vehicle phase and the mass percentage of each component are shown in Table 1.

[0045] 2. Disperse 60g of yttrium-doped zirconia ceramic powder with a particle size of 0.5u, 14.5g of yttrium-doped zirconia ceramic powder with a particle size of 1.5u and 0.5g of chloroplatinic acid with absolute ethanol to prepare For the premix, use ball milling to mix the premix evenly, and then dry it in an oven at 80°C.

[0046] 3. Place the dried powder in a resistance furnace for calcination at 900°C for 2 hours, and then grind the calcined powder with a mortar.

[0047] 4. ...

Embodiment 3

[0050] 1. Prepare the organic vehicle: add the binder into the solvent in a certain amount, then place it in a magnetic stirrer, set the temperature at 80°C, and the magnetron speed at 200-400r / min, until the binder is fully dissolved in the After being put into the solvent, add plasticizer, leveling agent, thixotropic agent and dispersant in proportion to configure 25g of organic vehicle. The components in the organic vehicle phase and the mass percentage of each component are shown in Table 1.

[0051] 2. Disperse 70g of yttrium-doped zirconia ceramic powder and 0.5g of rhodium trichloride hydrate with anhydrous ethanol to prepare a premixed solution, mix the premixed solution evenly by ball milling, and then place it at 80°C Dry in oven.

[0052] 3. Place the dried powder in a resistance furnace for calcination at 900°C for 2 hours, and then grind the calcined powder with a mortar.

[0053] 4. Mix the ground powder in step 3, 4.5g of magnesium aluminate spinel and 25g of t...

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Abstract

The invention relates to an outer electrode protection layer of an automobile tail gas sensor and a preparation method. The preparation method comprises the following steps of mixing an organic carrier phase with a functional phase according to a mass ratio of 25: 75, and preparing protection layer slurry with good uniformity through a rolling or a ball milling way; printing the protection layer slurry on the surface of an outer electrode green body of an automobile sensor in a silk-screen printing manner, wherein the thickness is 20 to 60 micrometers, and sintering the green body for 2 hours at the temperature of 1300DEG C to 1500DEG C; the aperture of each pore of the protection layer reaches the nanometer grade, little precious metal with catalytic activity is uniformly dispersed in the protection layer, so that the carbon oxide (CO), hydrocarbon and oxygen (O2) which are incompletely reacted in the tail gas exhausted by an engine can be adequately reacted, the signal reaction speed of the automobile sensor is higher, poisoning is unlikely to occur, and the service life is longer.

Description

technical field [0001] The invention relates to a preparation method of an oxygen sensor chip, in particular to a protective layer for an outer electrode of an automobile exhaust sensor and a preparation method thereof. The protective layer prepared by the method can improve the signal response speed of the oxygen sensor, effectively prevent poisoning of the oxygen sensor and prolong the its service life. Background technique [0002] Oxygen sensor is the core component of automobile EFI system, mainly used to monitor the oxygen content in automobile exhaust. The closed-loop control system composed of oxygen sensor and three-way catalyst greatly reduces the harmful emissions produced by the engine and satisfies the meet the requirements of the emission regulations at that time. However, oxygen sensor poisoning is a frequent and difficult to prevent and control failure. Gasoline and engine oil contain impurities such as lead, sulfur, and phosphorus, which will greatly reduce...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N27/30G01N27/409
Inventor 谢光远石亮
Owner 湖北盛时杰精密机电有限公司
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