CN210243549U - Gas sensor and ceramic chip thereof - Google Patents
Gas sensor and ceramic chip thereof Download PDFInfo
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- CN210243549U CN210243549U CN201920955662.2U CN201920955662U CN210243549U CN 210243549 U CN210243549 U CN 210243549U CN 201920955662 U CN201920955662 U CN 201920955662U CN 210243549 U CN210243549 U CN 210243549U
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Abstract
The application discloses gas sensor and ceramic chip thereof. The ceramic chip comprises a heater, wherein the heater comprises an upper layer, a middle layer and a lower layer which are respectively an upper insulating isolation layer, a heating conducting circuit and a lower insulating isolation layer; the main components of the upper insulating isolation layer and the lower insulating isolation layer are both aluminum oxide; the upper insulating isolation layer and the lower insulating isolation layer are both of structures with holes; the holes of the upper insulating isolation layer are different from the holes of the lower insulating isolation layer; a cavity gas guide groove of the gas sensor ceramic chip is arranged above the upper insulating isolation layer; and a zirconia base layer of the gas sensor ceramic chip is arranged below the lower insulating isolation layer. The gas sensor includes the ceramic chip. The application can effectively improve the heat effect resistance of the heater of the ceramic chip.
Description
Technical Field
The application relates to the technical field of gas sensors, in particular to a gas sensor and a ceramic chip thereof.
Background
At present, the ceramic chip of the gas sensor applied to the high-temperature environment mainly takes zirconia as a substrate. The working principle is that according to the oxygen ion conducting characteristic of the zirconia electrolyte at high temperature, a bidirectional working mechanism of the Nernst cell and the electrolytic cell is adopted. The main source of high temperature is a heater built into the zirconia matrix. The heater mainly comprises a conductive circuit and an insulating isolation layer. The main material of the insulating spacer layer is a non-conductive material, such as alumina.
Typical gas sensors are subject to thermal cycling during operation. The heater is in a very harsh thermal environment. Especially, the thermal expansion coefficient of the alumina of the insulating isolation layer is not matched with the zirconia of the substrate and the heating conductive circuit, so that the collapse and the failure of the ceramic structure can be directly brought, and the sensor can not work normally. In addition, the heater rapidly increases in temperature at the moment when the sensor is activated. The heat of the insulating isolation layer of the sensor increases rapidly, and if the heat cannot be effectively transferred, the structure can collapse.
The insulating isolation layer is distributed on the upper surface and the lower surface of the conductive circuit of the heater. The structure of the upper and lower surfaces of the insulating isolation layer is asymmetrical with respect to the ceramic chip. The upper insulating isolation layer corresponds to the cavity air guide groove of the ceramic chip, and the lower insulating isolation layer corresponds to the zirconia base layer of the ceramic chip. The asymmetric structure can directly cause that the heat quantity faced by the insulation isolation layers on the upper surface and the lower surface is different at the moment of heating starting, and the structure of the insulation isolation layers is easy to lose efficacy.
The above thermal effect directly leads to a reduction in the lifetime of the sensor ceramic chip.
The above background disclosure is only for the purpose of assisting in understanding the inventive concepts and technical solutions of the present application and does not necessarily pertain to the prior art of the present application, and should not be used to assess the novelty and inventive step of the present application in the absence of explicit evidence to suggest that such matter has been disclosed at the filing date of the present application.
SUMMERY OF THE UTILITY MODEL
The application provides a gas sensor and ceramic chip thereof, can improve the whole heater of ceramic chip to the endurance of heat effect to improve the life-span of heater.
In a first aspect, the present application provides a gas sensor ceramic chip, comprising a heater, wherein the heater comprises an upper layer, a middle layer and a lower layer, which are respectively an upper insulating isolation layer, a heating conductive circuit and a lower insulating isolation layer;
the main components of the upper insulating isolation layer and the lower insulating isolation layer are both aluminum oxide;
the upper insulating isolation layer and the lower insulating isolation layer are both of structures with holes;
the holes of the upper insulating isolation layer are different from the holes of the lower insulating isolation layer;
a cavity gas guide groove of the gas sensor ceramic chip is arranged above the upper insulating isolation layer;
and a zirconia base layer of the gas sensor ceramic chip is arranged below the lower insulating isolation layer.
In some preferred embodiments, the upper insulating spacer layer has a porosity 5% to 15% greater than the porosity of the lower insulating spacer layer.
In some preferred embodiments, the upper insulating spacer layer and the lower insulating spacer layer each comprise alumina particles of different particle sizes.
In a second aspect, the present application also provides a gas sensor comprising the above gas sensor ceramic chip.
Compared with the prior art, the beneficial effect of this application has:
the upper insulating isolation layer and the lower insulating isolation layer are in a structure with holes, and the upper insulating isolation layer and the lower insulating isolation layer are in an asymmetric layout, so that the heat effect resistance of the heater of the ceramic chip can be effectively improved, and the service life of the heater is prolonged.
Drawings
FIG. 1 is a schematic flow chart illustrating a method of fabricating a ceramic chip heater for a gas sensor according to an embodiment of the present disclosure;
FIG. 2 is a schematic structural diagram of a gas sensor ceramic chip according to an embodiment of the present disclosure;
FIG. 3 is a front structure of an insulating isolation layer of a gas sensor ceramic chip according to an embodiment of the present application;
FIG. 4(a) is a schematic view of a hole structure according to an embodiment of the present application;
FIG. 4(b) is a microscopic view of a pore structure according to an embodiment of the present application;
fig. 5 is a graph comparing thermal effects of examples of the present application.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the embodiments of the present application more clearly apparent, the present application is further described in detail below with reference to fig. 1 to 5 and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship indicated in the drawings that is solely for the purpose of facilitating the description of the embodiments and simplifying the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered as limiting the application.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present application, "a plurality" means two or more unless specifically defined otherwise.
The present embodiment provides a gas sensor ceramic chip including a heater. The heater of the present embodiment includes upper, middle and lower three layers. Referring to fig. 2 and 3, the three layers are an upper insulating isolation layer 1, a heating conductive line 2 and a lower insulating isolation layer 3, respectively.
The main components of the upper insulating isolation layer 1 and the lower insulating isolation layer 3 are both alumina.
The upper insulating isolation layer 1 and the lower insulating isolation layer 3 are both in a structure with holes. These holes may be used for heat transfer. A diaphragm or a plate with holes can be selected as an upper insulating isolation layer 1 and a lower insulating isolation layer 3; the diaphragm or plate with holes can be formed by laser processing; the upper insulating spacer 1 and the lower insulating spacer 3 may be formed by a manufacturing method described later in this embodiment.
The holes of the upper insulating isolation layer 1 are different from the holes of the lower insulating isolation layer 3. In particular, the two layers have different pore sizes, different porosities or different pore distributions.
The upper part of the upper insulating isolation layer 1 is a cavity air guide groove of the ceramic chip of the gas sensor, or the upper insulating isolation layer 1 corresponds to the cavity air guide groove of the ceramic chip. Below the lower insulating barrier layer 3 is the zirconia base layer of the ceramic chip of the gas sensor, or the lower insulating barrier layer 3 corresponds to the zirconia base layer 4 of the ceramic chip. Thus, an asymmetric structure is formed in the gas sensor ceramic chip.
The upper insulating spacer 1 and the lower insulating spacer 3 are also asymmetric, which means that different alumina structure layers are applied to the upper insulating spacer 1 and the lower insulating spacer 3. Depending on the heat transfer capacity, the porosity of the upper insulating barrier layer 1 can be adjusted to a higher level, about 5% to 15% higher than that of the lower insulating barrier layer 3.
In this embodiment, the upper insulating isolation layer 1 and the lower insulating isolation layer 3 are in a structure with holes, and the upper insulating isolation layer and the lower insulating isolation layer are in an asymmetric layout, so that the heat effect resistance of the heater of the ceramic chip can be effectively improved, and the service life of the heater can be prolonged.
The present embodiment further provides a gas sensor, including the gas sensor ceramic chip of the present embodiment.
The embodiment provides an insulating slurry of a gas sensor ceramic chip, which comprises a pore-forming agent and aluminum oxide particles.
In the present embodiment, referring to fig. 4(a) and 4(b), the alumina particles include alumina (Al) of different particle sizes2O3) The mixing of (2) comprises mixing two or more powders. Specifically, the alumina particles include main alumina particles and complex alumina particles. The particle size of the bulk alumina particles is in the range of 1-2 μm. The particle size range of the complex alumina particles is 300-500nm or 5-10 μm.
The manner of incorporation of the alumina particles of different particle sizes may vary. The volume fraction of the alumina particles in the main body is generally controlled to be about 70%, and the components of the alumina particles can be adjusted according to the actual design.
The pore-forming agent can be graphite, carbon black, ammonium nitrate, starch or other sacrificial materials or escape materials, and the materials can volatilize at high temperature to form a certain pore structure.
The mass fraction of the pore-forming agent is between 10 and 40 percent. The alumina particles are the main component of the insulating slurry, and the specific mass fraction can be selected according to the requirement, for example, the rest are the alumina particles.
In other embodiments, the insulating paste may further include 0% to 3% by mass or up to 3% by mass of an additive, preferably 2% to 3%. The main component of the additive is a mixture of silicon oxide, magnesium oxide and aluminum oxide; or at least two of silica, magnesia and alumina. Under the action of the additive, the sintering capacity of the main alumina particles can be effectively improved, and a pore structure can be formed at the same time.
The insulating slurry in the embodiment can effectively improve the matching of the insulating layer on the zirconia base body of the ceramic chip of the gas sensor through the holes formed by adjusting the components, and the aluminum oxide with different particle sizes can be mixed and sintered to form various hole structures, so that the heat effect resistance can be improved.
The embodiment provides a manufacturing method of a gas sensor ceramic chip heater. The method uses an upper layer of insulating paste and a lower layer of insulating paste. The upper layer insulating paste and the lower layer insulating paste are the insulating pastes described above in this embodiment. The structure of the holes formed by the upper layer of insulating slurry is different from the structure of the holes formed by the lower layer of insulating slurry. Referring to fig. 1, the manufacturing method of the present embodiment includes steps S1 to S3.
And step S1, mixing the upper layer insulating slurry and the lower layer insulating slurry respectively to form upper layer slurry and lower layer slurry.
And step S2, printing the upper layer slurry and the lower layer slurry on the upper layer and the lower layer of the heating conductive circuit respectively to obtain the heater to be processed.
And step S3, performing subsequent treatment on the heater to be treated to obtain the heater with an integrated structure. One form of post-processing is, among others, lamination, cutting and sintering of the heater to be processed.
The holes of the upper insulating isolation layer 1 are different from the holes of the lower insulating isolation layer 3, and the component proportion of the slurry forming the upper insulating isolation layer 1 and the slurry of the lower insulating isolation layer 3 can be adjusted through the adjustment, so that the particle sizes of the main alumina particles of the upper-layer slurry and the lower-layer slurry are different.
For the heater obtained by the manufacturing method of this embodiment, the upper insulating isolation layer 1 and the lower insulating isolation layer 3 both include alumina particles with different particle sizes, specifically, main alumina particles and complex alumina particles. The particle size of the bulk alumina particles is in the range of 1-2 μm. The particle size range of the complex alumina particles is 300-500nm or 5-10 μm.
The present example is explained below by way of experimental examples and comparative examples.
There are three insulating pastes, insulating paste a1, insulating paste a2, and insulating paste A3.
Insulating paste a 1: the alumina particle size was about 1-2um, ball milled to a particle size distribution D50 of about 500nm, and mixed with 30% of pore former graphite to form a slurry.
Insulating paste a 2: the alumina particle size was about 1-2um, ball milled to a particle size distribution D50 of about 500nm, and mixed with 20% of pore former graphite to form a slurry.
Insulating paste a 3: the alumina particle size was about 1-2um and the D50 ball milled to a particle size distribution of about 500nm, with no added pore former graphite.
Experimental example 1
The insulating paste a1 was printed on the upper layer of the heating conductive trace, and the insulating paste a2 was printed on the lower layer of the heating conductive trace. After a subsequent series of lamination, cutting and sintering processes, an integral structure of the heater was formed, labeled sample Samples-a, as shown in fig. 4.
For comparison, two additional Samples were prepared, Samples-B and Samples-C, respectively.
Comparative example 1
Samples-B is a symmetrical insulating structure of upper and lower layers formed by insulating paste a 2.
Comparative example 2
Samples-C is a symmetrical insulation structure formed by insulation paste a 3.
The three samples were divided into two groups to compare the thermal shock versus the cold thermal cycle characteristics.
The thermal shock method is starting from room temperature to 950 ℃, the starting time is not more than 5 seconds, the temperature is kept for 1 second, the temperature is naturally reduced to the room temperature, and the process is circulated.
The cold and hot circulation method is that the temperature is started from room temperature to 900 ℃, the starting time is not more than 10 seconds, the temperature is kept for 10 seconds, the temperature is cooled to room temperature by air cooling, the temperature is kept for 10 seconds, and the process is circulated.
The functional life was directly compared and the results of the comparative experiment are shown in fig. 5. For thermal shock, the effective number of Samples-A, Samples-B and Samples-C, respectively, is: 600. 500 and 200. For thermal cycling, the effective number of Samples-A, Samples-B and Samples-C, respectively, is: 1200. 950 and 600. The results for Samples-A are significantly superior to those for Samples-B, which is significantly superior to that for Samples-C. It can be seen that the sample with the hole structure has better tolerance to thermal shock, and the non-symmetrical structure with the hole has better tolerance to thermal shock and cold and hot cycles.
According to the method, the tolerance of the heater of the ceramic chip of the gas sensor to the heat effect can be improved, the heater is matched with thermal expansion, heat transfer can be improved, and the service life of the heater can be effectively prolonged.
The foregoing is a further detailed description of the present application in connection with specific/preferred embodiments and is not intended to limit the present application to that particular description. For a person skilled in the art to which the present application pertains, several alternatives or modifications to the described embodiments may be made without departing from the concept of the present application, and these alternatives or modifications should be considered as falling within the scope of the present application.
Claims (4)
1. A gas sensor ceramic chip, characterized in that: the heater comprises an upper layer, a middle layer and a lower layer, wherein the upper layer, the middle layer and the lower layer are respectively an upper insulating isolation layer, a heating conducting circuit and a lower insulating isolation layer;
the main components of the upper insulating isolation layer and the lower insulating isolation layer are both aluminum oxide;
the upper insulating isolation layer and the lower insulating isolation layer are both of structures with holes;
the holes of the upper insulating isolation layer are different from the holes of the lower insulating isolation layer;
a cavity gas guide groove of the gas sensor ceramic chip is arranged above the upper insulating isolation layer;
and a zirconia base layer of the gas sensor ceramic chip is arranged below the lower insulating isolation layer.
2. The gas sensor ceramic chip according to claim 1, wherein: the upper insulating isolation layer has a porosity 5% to 15% greater than a porosity of the lower insulating isolation layer.
3. The gas sensor ceramic chip according to claim 1, wherein: the upper insulating isolation layer and the lower insulating isolation layer each include alumina particles of different particle sizes.
4. A gas sensor, characterized by: comprising a gas sensor ceramic chip according to any one of claims 1 to 3.
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| CN201920955662.2U CN210243549U (en) | 2019-06-24 | 2019-06-24 | Gas sensor and ceramic chip thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110196268A (en) * | 2019-06-24 | 2019-09-03 | 深圳市森世泰科技有限公司 | Gas sensor and its ceramic chip and insulation paste and production method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110196268A (en) * | 2019-06-24 | 2019-09-03 | 深圳市森世泰科技有限公司 | Gas sensor and its ceramic chip and insulation paste and production method |
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