A wide-range oxygen sensor

Abstract

The present invention relates to a wide-range oxygen sensor, which is additionally provided with a solid electrolyte layer as a transmission path for oxygen ions, and is used together with the induction battery electrolyte layer for the transmission of oxygen ions, thereby adding a transmission path, thereby breaking through the lower limit of the adjustment of the internal resistance value of the sensor battery in the prior art, and achieving a lower limit value several times higher than the prior art. The second electrode of the sensor battery and the first electrode of the sensor battery are spaced apart and arranged on the same side surface of the sensor battery electrolyte layer, and then by adjusting the facing width and spacing between the second electrode of the sensor battery and the first electrode of the sensor battery, the transmission distance of the oxygen ions can be increased, thereby increasing the internal resistance of the sensor battery, breaking through the upper limit of the adjustment of the internal resistance value of the sensor battery in the prior art, and achieving an upper limit value several times higher than the prior art. In the present invention, the second electrode of the sensor battery and the first electrode of the sensor battery are spaced apart and arranged at the same end of the sensor battery electrolyte layer, and the diffusion barrier and the solid electrolyte layer are prepared by nesting cast sheets, thereby improving production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of oxygen sensors, and more particularly to a wide-range oxygen sensor. Background Art

[0002] The automotive oxygen sensor, also known as the air-fuel ratio oxygen sensor, is a key and essential sensing component in the electronic fuel injection engine control system. It is a key component for controlling automobile exhaust emissions, reducing automobile pollution to the environment, and improving the fuel combustion quality of automobile engines.

[0003] Traditional switch-type oxygen sensors can no longer meet the increasingly stringent emission requirements, and are replaced by linear wide-range oxygen sensors with higher control accuracy. The air-fuel ratio oxygen sensor can accurately detect the oxygen concentration in the exhaust gas under different engine operating conditions, and promptly transmit the signal to the on-board computer to accurately calculate and control the concentration of the mixed gas, so that the engine can achieve a more ideal air-fuel ratio, thereby achieving better engine combustion, more power, lower fuel consumption, and less emission pollution.

[0004] Common air-fuel ratio oxygen sensors mainly include 4-wire air-fuel ratio oxygen sensors and 5-wire air-fuel ratio oxygen sensors. Temperature control is achieved by monitoring the internal resistance of the sensing battery. The product's temperature-sensing battery internal resistance curve is required to meet the parameter requirements of the controller.

[0005] The air-fuel ratio oxygen sensor of the prior art has different temperature control strategies according to the different electrolyte materials and battery structures. In the prior art, the inductive battery structure of the air-fuel ratio oxygen sensor has certain limitations due to the limitation of the structural principle, that is, it cannot meet the requirements of different inductive battery internal resistance values. For example, in the inductive battery structure, Figure 1 As shown in the figure, the sensing outer electrode 100 and the sensing inner electrode 101 are respectively arranged on both sides of the sensing layer electrolyte 102, and the internal resistance of the sensing battery is mainly determined by the electrolyte material and the battery structure, such as the conductivity and thickness of the sensing layer electrolyte 102, and the directly facing projection area of ​​the sensing outer electrode 100 and the sensing inner electrode 101. Furthermore, in the case where the material of the sensing layer electrolyte 102 is not changed, it can only be achieved by adjusting the thickness of the sensing layer electrolyte 102 and the directly facing projection area of ​​the sensing outer electrode 100 and the sensing inner electrode 101, resulting in the following deficiencies:

[0006] 1. The adjustable range is narrow, usually only within 100Ω, which cannot meet the requirements of different internal resistance values ​​of induction batteries;

[0007] 2. The distance between the sensing outer electrode 100 and the sensing inner electrode 101 is adjusted by adjusting the thickness of the sensing layer electrolyte 102, which requires process modification for the sensing layer electrolyte 102; moreover, when the distance between the sensing outer electrode 100 and the sensing inner electrode 101 is increased by thickening the sensing layer electrolyte 102, the cost is directly increased;

[0008] 3. The sensing outer electrode 100 and the sensing inner electrode 101 are respectively arranged on both sides of the sensing layer electrolyte 102. When the facing projection area of ​​the sensing outer electrode 100 and the sensing inner electrode 101 is reduced, the sensing outer electrode 100 and the sensing inner electrode 101 will form staggered electrodes, resulting in an uncertain transmission path of oxygen ions, which will cause abnormal output voltage. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a wide-range oxygen sensor to achieve wide-range adjustment of the internal resistance of the sensor battery and meet the requirements of different internal resistance values ​​of the sensor battery.

[0010] The technical solution of the present invention is as follows:

[0011] A wide-range oxygen sensor comprises a heating part, a sensing cell part and a pump cell part. The sensing cell part comprises a sensing cell electrolyte layer, a sensing cell first electrode, a sensing cell second electrode and a diffusion barrier. The sensing cell part also comprises a solid electrolyte layer. The sensing cell first electrode is arranged between the sensing cell electrolyte layer and the diffusion barrier. The sensing cell second electrode and the sensing cell first electrode are arranged on the same side surface of the sensing cell electrolyte layer with a spacing. The sensing cell second electrode is arranged between the sensing cell electrolyte layer and the solid electrolyte layer. The sensing cell electrolyte layer and the solid electrolyte layer are used for the transmission of oxygen ions.

[0012] Preferably, the second electrode of the sensor battery is prepared on the surface of the electrolyte layer of the sensor battery, and the solid electrolyte layer is prepared on the surface of the electrolyte layer of the sensor battery and covers the second electrode of the sensor battery.

[0013] Preferably, the first electrode of the sensor cell is located within the range covered by the diffusion barrier, and the second electrode of the sensor cell is located within the range covered by the solid electrolyte layer.

[0014] Preferably, a filling matrix layer is arranged between the pump cell part and the sensor cell part, the diffusion barrier, the solid electrolyte layer and the filling matrix layer are arranged in the same layer, and the diffusion barrier and the solid electrolyte layer are arranged adjacent to each other.

[0015] Preferably, the first electrode of the sensor cell and the second electrode of the sensor cell are arranged at the same end of the electrolyte layer of the sensor cell.

[0016] Preferably, the leads of the first electrode of the sensor cell and the second electrode of the sensor cell extend to the other end of the electrolyte layer of the sensor cell.

[0017] Preferably, the opposite ends of the first electrode of the sensor battery and the second electrode of the sensor battery are of a concave-convex corresponding structure.

[0018] Preferably, the solid electrolyte layer is a zirconium oxide filling layer.

[0019] Preferably, when the electrolyte layer of the sensor battery remains unchanged, when the distance between the first electrode of the sensor battery and the second electrode of the sensor battery is increased, or the projection area directly facing the first electrode of the sensor battery and the second electrode of the sensor battery is reduced, the internal resistance of the sensor battery increases; when the distance between the first electrode of the sensor battery and the second electrode of the sensor battery is reduced, or the projection area directly facing the first electrode of the sensor battery and the second electrode of the sensor battery is increased, the internal resistance of the sensor battery decreases.

[0020] Preferably, the heating part and the sensor cell part are provided with a substrate part, and the substrate part comprises an alumina substrate layer, a zirconium oxide substrate layer and an alumina substrate layer which are sequentially arranged from the sensor cell part to the heating part, and the alumina substrate layer is one layer or multiple layers.

[0021] The beneficial effects of the present invention are as follows:

[0022] The wide-band oxygen sensor of the present invention is provided with a solid electrolyte layer as a transmission path for oxygen ions, which is used together with the induction battery electrolyte layer for the transmission of oxygen ions, thereby adding a transmission path, thereby breaking through the lower limit of the adjustment of the internal resistance value of the sensor battery in the prior art and achieving a lower limit value several times higher than the prior art.

[0023] The present invention arranges the second electrode of the sensor battery and the first electrode of the sensor battery at the same side surface of the electrolyte layer of the sensor battery, and then adjusts the projection area and / or spacing between the second electrode of the sensor battery and the first electrode of the sensor battery to adjust the internal resistance of the sensor battery. When the distance between the first electrode of the sensor battery and the second electrode of the sensor battery is increased, the transmission distance of oxygen ions can be increased, or the projection area between the first electrode of the sensor battery and the second electrode of the sensor battery can be reduced, which can increase the internal resistance of the sensor battery, break through the upper limit of the internal resistance value of the sensor battery in the prior art, and achieve several times the upper limit of the prior art. Conversely, the internal resistance of the sensor battery can be reduced.

[0024] The present invention arranges the second electrode of the sensor battery and the first electrode of the sensor battery at the same end of the electrolyte layer of the sensor battery, and the solid electrolyte layer can be arranged next to the diffusion barrier. The diffusion barrier and the solid electrolyte layer can be prepared by nesting cast sheets to improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a cross-sectional view of the prior art;

[0026] Figure 2 It is a structural exploded diagram of the present invention;

[0027] Figure 3 is a longitudinal cross-sectional view of the present invention (showing the transport path of oxygen ions);

[0028] Figure 4 yes Figure 3 A schematic diagram of a local A enlargement;

[0029] Figure 5 yes Figure 3 AA cross-sectional diagram of ;

[0030] Figure 6 It is a longitudinal cross-sectional view of the present invention (the distance between the first electrode of the sensor battery and the second electrode of the sensor battery is relatively large);

[0031] Figure 7 is a longitudinal cross-sectional view of the present invention (the distance between the first electrode of the sensor battery and the second electrode of the sensor battery is small);

[0032] Figure 8 Schematic diagram of the first electrode of the sensor battery and the second electrode of the sensor battery (conventional facing projection area);

[0033] Fig. 9 is a schematic diagram of the first electrode of the sensor battery and the second electrode of the sensor battery (the opposite projection area is smaller);

[0034] Fig.10 It is a schematic diagram of the first electrode of the sensor battery and the second electrode of the sensor battery (the projection area facing each other is larger);

[0035] In the figure: 100 is the sensing outer electrode, 101 is the sensing inner electrode, 102 is the sensing layer electrolyte, 11 is the heater, 12 is the insulating substrate layer, 13 is the heater pin, 21 is the sensing battery electrolyte layer, 22 is the sensing battery first electrode, 23 is the sensing battery second electrode, 24 is the diffusion barrier, 25 is the solid electrolyte layer, 31 is the pump battery electrolyte layer, 32 is the pump battery first electrode, 33 is the pump battery second electrode, 41 is the insulating protective layer, 42 is the porous protective layer, 43 is the electrode pin, 50 is the filling substrate layer, 51 is the first alumina substrate layer, 52 is the second alumina substrate layer, 53 is the zirconia substrate layer, and 54 is the third alumina substrate layer. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0037] In order to solve the problem that the internal resistance value of the sensing battery in the prior art is limited in the adjustable range of the internal resistance of the sensing battery without changing the electrolyte material of the sensing battery due to the structural principle, the present invention provides a wide-range oxygen sensor, which can break through the adjustable range of the internal resistance of the sensing battery in the prior art without changing the electrolyte material of the sensing battery, greatly reduce the lower limit value, and greatly increase the upper limit value, and can realize the adjustment of the internal resistance of the sensing battery from tens of ohms to thousands of ohms, meeting the requirements of different internal resistance values ​​of the sensing battery.

[0038] The wide-range oxygen sensor of the present invention is as follows: Figure 2 , Figure 3 , Figure 4 As shown, it includes a heating part, a sensor cell part, and a pump cell part. The heating part, the sensor cell part, and the pump cell part are arranged in sequence from bottom to top. A protective layer part is also arranged on the pump cell part. A filling matrix layer 50 is arranged between the pump cell part and the sensor cell part (that is, the pump cell part and the sensor cell part are separated by an insulating filling matrix layer 50, and the filling matrix layer 50 is implemented as an aluminum oxide filling matrix layer 50).

[0039] The heating part includes a heater 11, an insulating substrate layer 12 (the insulating substrate layer 12 is implemented as an aluminum oxide substrate layer), and two heater pins 13. The pump battery part includes a pump battery electrolyte layer 31, a pump battery first electrode 32, and a pump battery second electrode 33. The pump battery first electrode 32 and the pump battery second electrode 33 are respectively arranged on the upper surface and the lower surface of the pump battery electrolyte layer 31. The protective layer part includes an insulating protective layer 41 (the insulating protective layer 41 is implemented as an aluminum oxide protective layer), a porous protective layer 42, and three electrode pins 43. This embodiment is a five-wire oxygen sensor.

[0040] The sensor battery part includes a sensor battery electrolyte layer 21, a sensor battery first electrode 22, a sensor battery second electrode 23, a diffusion barrier 24, and a solid electrolyte layer 25. The sensor battery first electrode 22 is arranged between the sensor battery electrolyte layer 21 and the diffusion barrier 24. The sensor battery second electrode 23 and the sensor battery first electrode 22 are arranged on the same side surface of the sensor battery electrolyte layer 21. The sensor battery second electrode 23 is arranged between the sensor battery electrolyte layer 21 and the solid electrolyte layer 25. Both the sensor battery electrolyte layer 21 and the solid electrolyte layer 25 can be used for the transmission of oxygen ions. In this embodiment, the solid electrolyte layer 25 is a zirconium oxide filling layer.

[0041] In the thickness direction, the porous protective layer 42, the pump cell first electrode 32, the pump cell second electrode 33, the diffusion barrier 24, and the sensor cell first electrode 22 are arranged substantially opposite to each other.

[0042] In the present invention, the second electrode 23 of the sensor battery and the first electrode 22 of the sensor battery are arranged at intervals on the same side surface of the electrolyte layer 21 of the sensor battery. Compared with the prior art, the prior art arranges the two electrodes of the sensor battery on both sides of the electrolyte of the sensor battery. When the directly opposite projection area of ​​the two electrodes of the sensor battery is reduced, the two electrodes of the sensor battery will form staggered electrodes, resulting in an uncertain transmission path of oxygen ions, which will cause abnormal output voltage. The present invention adjusts the distance between the second electrode 23 of the sensor battery and the first electrode 22 of the sensor battery in the horizontal direction. Compared with the prior art that adjusts the distance between the two electrodes of the sensor battery in the thickness direction (usually achieved by increasing the thickness of the electrolyte layer of the sensor battery), it is easier to implement and prepare, and does not need to change the thickness and material of the electrolyte layer 21 of the sensor battery, that is, it does not need to change the preparation process parameters, especially it does not need to increase the thickness of the electrolyte layer 21 of the sensor battery to increase the distance between the second electrode 23 of the sensor battery and the first electrode 22 of the sensor battery, which can save the material use of the electrolyte layer 21 of the sensor battery.

[0043] For ease of setting and adjustment, the first electrode 22 of the sensor battery and the second electrode 23 of the sensor battery are arranged at the same end of the electrolyte layer 21 of the sensor battery (corresponding to the porous protective layer 42, the diffusion barrier 24 and the solid electrolyte layer 25). The leads of the first electrode 22 of the sensor battery and the second electrode 23 of the sensor battery extend to the other end of the electrolyte layer 21 of the sensor battery (corresponding to the electrode pin 43 of the protective layer). Figure 8 As shown, the opposite ends of the first sensor battery electrode 22 and the second sensor battery electrode 23 are of corresponding concave and convex structures, for example, the opposite ends of the first sensor battery electrode 22 and the second sensor battery electrode 23 are configured as corresponding convex arc ends and concave arc ends.

[0044] Based on the structure that the second electrode 23 of the sensor battery and the first electrode 22 of the sensor battery are arranged at the same side surface of the electrolyte layer 21 of the sensor battery, and the electrolyte layer 21 of the sensor battery and the solid electrolyte layer 25 can both be used to transmit oxygen ions, the present invention does not change the electrolyte layer 21 of the sensor battery, especially does not change the material and thickness of the electrolyte layer 21 of the sensor battery, when the distance between the first electrode 22 of the sensor battery and the second electrode 23 of the sensor battery is increased (such as Figure 6 As shown), or reduce the projection area of ​​the first electrode 22 of the sensor battery and the second electrode 23 of the sensor battery (as shown Fig. 9 As shown), the internal resistance of the sensing battery increases; when the distance between the first electrode 22 of the sensing battery and the second electrode 23 of the sensing battery is reduced (as shown Figure 7 As shown), or increase the projection area of ​​the first electrode 22 of the sensor battery and the second electrode 23 of the sensor battery (as shown Fig.10 As shown), the internal resistance of the induction battery decreases.

[0045] Due to the structure that the second electrode 23 of the sensor battery and the first electrode 22 of the sensor battery are spaced apart and arranged on the same side surface of the electrolyte layer 21 of the sensor battery, the projected area facing each other of the second electrode 23 of the sensor battery and the first electrode 22 of the sensor battery is greatly reduced, and the number of oxygen ions passing through per unit time is greatly reduced, and the internal resistance of the sensor battery can generally reach the kilo-ohm level (for products with a higher lower limit, the solid electrolyte layer 25 may not be provided). When the distance between the second electrode 23 of the sensor battery and the first electrode 22 of the sensor battery is reduced, and the projected area facing each other of the second electrode 23 of the sensor battery and the first electrode 22 of the sensor battery is increased to an extreme value, the demand for a small inductive internal resistance value (for example, 300Ω) cannot be met, and it is easy to cause abnormal output voltage. Figure 5 As shown, in the present invention, the second electrode 23 of the cooperative sensor battery and the first electrode 22 of the sensor battery are spaced apart and arranged on the same side surface of the sensor battery electrolyte layer 21, and the sensor battery electrolyte layer 21 and the solid electrolyte layer 25 can both be used to transmit oxygen ions. By increasing the transmission path of oxygen ions, the internal resistance of the sensor battery is further reduced, thereby achieving the effect of greatly improving the upper limit value and greatly reducing the lower limit value of the internal resistance of the sensor battery.

[0046] In order to better realize the transmission of oxygen ions in the solid electrolyte layer 25 and the sensor battery electrolyte layer 21 at the same time, in this embodiment, the sensor battery second electrode 23 is prepared on the surface of the sensor battery electrolyte layer 21, and the solid electrolyte layer 25 is prepared on the surface of the sensor battery electrolyte layer 21 and covers the sensor battery second electrode 23. That is, the solid electrolyte layer 25 is arranged in close contact with the sensor battery electrolyte layer 21, and the oxygen ions are released from the sensor battery first electrode 22 and enter the sensor battery electrolyte layer 21. A part of the oxygen ions is directly transmitted to the sensor battery second electrode 23 through the sensor battery electrolyte layer 21, and a part of the oxygen ions first enter the solid electrolyte layer 25 through the sensor battery electrolyte layer 21, and then transmitted to the sensor battery second electrode 23 through the solid electrolyte layer 25, so as to realize dual-medium dual-path transmission.

[0047] In specific implementation, the first electrode 22 of the sensor cell is located within the coverage of the diffusion barrier 24, and the second electrode 23 of the sensor cell is located within the coverage of the solid electrolyte layer 25, ensuring that the solid electrolyte layer 25 can be effectively utilized for oxygen ion transmission.

[0048] In this embodiment, the diffusion barrier 24, the solid electrolyte layer 25 and the filling matrix layer 50 are arranged in the same layer, and according to the implementation requirements, the diffusion barrier 24 and the solid electrolyte layer 25 are arranged adjacent to each other, and the diffusion barrier 24 and the solid electrolyte layer 25 are located at the non-end position of the filling matrix layer 50 (the specific position corresponds to the setting position of the first electrode 22 of the sensor cell and the second electrode 23 of the sensor cell). During preparation, the diffusion barrier 24 and the solid electrolyte layer 25 are generated between the two ends of the filling matrix layer 50 by nesting the cast sheet, that is, a structure in which a part of the filling matrix layer 50, the diffusion barrier 24, the solid electrolyte layer 25, and another part of the filling matrix layer 50 are arranged in sequence is formed.

[0049] In order to enhance the strength of the present invention and prevent bending deformation, the heating part and the sensor battery part are provided with a substrate part, and the substrate part includes an alumina substrate layer, a zirconium oxide substrate layer 53, and an alumina substrate layer which are sequentially arranged from the sensor battery part to the heating part. The alumina substrate layer is one layer or multiple layers, such as a first alumina substrate layer 51, a second alumina substrate layer 52, a zirconium oxide substrate layer 53, and a third alumina substrate layer 54 which are sequentially arranged from the sensor battery part to the heating part.

[0050] During operation, the exhaust gas contacts the first electrode 22 of the sensor battery through the diffusion barrier 24, and oxygen moves from the first electrode 22 of the sensor battery through the sensor battery electrolyte layer 21 below it and the solid electrolyte layer 25 above it to the second electrode 23 of the sensor battery, providing reference oxygen for the second electrode 23 of the sensor battery. The size of the internal resistance of the sensor battery depends on the amount of oxygen ions transmitted between the first electrode 22 of the sensor battery and the second electrode 23 of the sensor battery per unit time. The amount of oxygen ion transmission per unit time depends on the transmission distance, the directly opposite projection area of ​​the first electrode 22 of the sensor battery and the second electrode 23 of the sensor battery, and the transmission path. Furthermore, when determining the internal resistance of the sensor battery of the product, the size of the internal resistance of the sensor battery can be changed by adjusting the distance between the first electrode 22 of the sensor battery and the second electrode 23 of the sensor battery, the directly opposite projection area, and the number of transmission channels, and the adjustable range is wide, which can meet the needs of different sensing internal resistance values.

[0051] The above embodiments are only used to illustrate the present invention, and are not used to limit the present invention. As long as they are based on the technical essence of the present invention, changes and modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A wide-range oxygen sensor, comprising a heating part, a sensor cell part, and a pump cell part, wherein the sensor cell part comprises a sensor cell electrolyte layer, a sensor cell first electrode, a sensor cell second electrode, and a diffusion barrier, characterized in that: The sensor battery part also includes a solid electrolyte layer. The first electrode of the sensor battery is arranged between the sensor battery electrolyte layer and the diffusion barrier. The second electrode of the sensor battery and the first electrode of the sensor battery are arranged on the same side surface of the sensor battery electrolyte layer with a spacing. The second electrode of the sensor battery is arranged between the sensor battery electrolyte layer and the solid electrolyte layer. The sensor battery electrolyte layer and the solid electrolyte layer are used for the transmission of oxygen ions.

2. The wide-band oxygen sensor according to claim 1, characterized in that: The second electrode of the sensor battery is prepared on the surface of the electrolyte layer of the sensor battery, and the solid electrolyte layer is prepared on the surface of the electrolyte layer of the sensor battery and covers the second electrode of the sensor battery.

3. The wide-band oxygen sensor according to claim 1, characterized in that: The first electrode of the sensor cell is located within the range covered by the diffusion barrier, and the second electrode of the sensor cell is located within the range covered by the solid electrolyte layer.

4. The wide-band oxygen sensor according to claim 3, characterized in that: A filling matrix layer is arranged between the pump battery part and the sensor battery part, the diffusion barrier, the solid electrolyte layer and the filling matrix layer are arranged in the same layer, and the diffusion barrier and the solid electrolyte layer are arranged adjacent to each other.

5. The wide-band oxygen sensor according to claim 1, characterized in that: The first electrode of the sensor cell and the second electrode of the sensor cell are arranged at the same end of the electrolyte layer of the sensor cell.

6. The wide-band oxygen sensor according to claim 5, characterized in that: The leads of the first electrode of the sensor battery and the second electrode of the sensor battery extend to the other end of the electrolyte layer of the sensor battery.

7. The wide-band oxygen sensor according to claim 1, characterized in that: The opposite ends of the first electrode of the sensor battery and the second electrode of the sensor battery are of a concave-convex corresponding structure.

8. The wide-band oxygen sensor according to claim 1, characterized in that: The solid electrolyte layer is a zirconium oxide filling layer.

9. The wide-band oxygen sensor according to any one of claims 1 to 8, characterized in that: When the electrolyte layer of the sensor battery remains unchanged, when the distance between the first electrode of the sensor battery and the second electrode of the sensor battery is increased, or the projection area directly facing the first electrode of the sensor battery and the second electrode of the sensor battery is reduced, the internal resistance of the sensor battery increases; when the distance between the first electrode of the sensor battery and the second electrode of the sensor battery is reduced, or the projection area directly facing the first electrode of the sensor battery and the second electrode of the sensor battery is increased, the internal resistance of the sensor battery decreases.

10. The wide-band oxygen sensor according to claim 1, characterized in that: The heating part and the sensor battery part are provided with a substrate part, which includes an aluminum oxide substrate layer, a zirconium oxide substrate layer and an aluminum oxide substrate layer which are sequentially provided from the sensor battery part to the heating part, and the aluminum oxide substrate layer is one layer or multiple layers.

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