Polarographic dissolved oxygen electrode structure

Abstract

The utility model discloses a polarogram type dissolved oxygen electrode structure which comprises an electrode connector, an electrode core assembly, a membrane assembly and a connecting mechanism. According to the electrode core assembly, a platinum wire is fused and sealed by a high borosilicate glass tube to form a cathode, and thermal stress is reduced by adopting a gradient annealing process; the anode is a pure silver cylinder with the wall thickness of 0.8 mm, and the surface of the anode is subjected to precise chlorination treatment to form an Ag / AgCl reference system; the PT100 temperature sensor is packaged by aluminum oxide ceramics and is fixed through high-temperature epoxy glue in a potting mode. The membrane assembly is formed by connecting a PEEK membrane pressing base and a 316L stainless steel fixing ring in an interference fit mode, so that a membrane is evenly stressed. The connecting mechanism adopts a multi-sealing design, EPDM sealing rings are arranged in a double-layer staggered mode, and the compression amount is controlled to be 25-30%. The whole structure adopts a modular design, the electrode response time is shortened to be within 30 seconds from traditional 45-60 seconds, the zero drift is reduced to 0.3-0.5% / month, the service life is prolonged by 2.5 times, the accuracy and stability of dissolved oxygen measurement are remarkably improved, and the device is suitable for the fields of environment monitoring, industrial process control and the like.

Description

Technical Field

[0001] This utility model relates to the field of bioengineering detection technology, and in particular to a polarographic dissolved oxygen electrode structure. Background Technology

[0002] Dissolved oxygen is a key parameter in water quality monitoring, widely used in environmental monitoring, industrial process control, aquaculture, and wastewater treatment. As an important indicator reflecting the self-purification capacity and ecological status of water bodies, accurate measurement of dissolved oxygen concentration plays an irreplaceable role in assessing water quality, ensuring the health of aquatic ecosystems, and optimizing industrial production processes. Currently, polarographic dissolved oxygen electrodes have become the mainstream technology for dissolved oxygen measurement due to their simple structure, wide measurement range, and strong anti-interference ability. Traditional polarographic dissolved oxygen electrodes typically use a silver / silver chloride reference electrode as the anode and platinum or gold as the cathode, measuring dissolved oxygen concentration by the current signal generated by the diffusion of oxygen molecules within the membrane and their reduction on the cathode surface. However, traditional electrode structures still have significant shortcomings in terms of stability, accuracy, response speed, and service life, making it difficult to meet the increasingly demanding requirements of modern industrial and environmental monitoring.

[0003] Traditional polarographic dissolved oxygen electrodes face several technical bottlenecks that urgently need to be overcome. First, the glass-sealing technology used in conventional electrodes often fails to achieve a precise match between the thermal expansion coefficients of glass and metal, leading to thermal stress accumulation. Under temperature fluctuations, this can easily cause microcracks, resulting in electrolyte leakage and measurement failure. Second, the traditional anode structure design is simple and does not consider the internal flow field distribution of the electrode, resulting in an excessively thick concentration boundary layer on the membrane surface. This leads to slow response speed, measurement lag, and an inability to accurately track rapid changes in dissolved oxygen concentration in water. Third, the integration of the temperature compensation system and the measurement unit is not high. The packaging method of the temperature sensor results in thermal response lag, affecting the accuracy of temperature compensation and causing significant errors under conditions of drastic temperature changes. Furthermore, traditional membrane fixing structures often use threaded connections, which are prone to loosening and seal aging during long-term use, making maintenance and replacement cumbersome and significantly increasing operating costs and downtime.

[0004] With the increasing demands for water environment management and industrial process control, dissolved oxygen measurement technology is evolving towards higher precision, higher reliability, lower maintenance, and multifunctional integration. On one hand, environmental monitoring, water treatment, and precision industrial production place higher demands on measurement accuracy and response speed, requiring electrodes to maintain measurement accuracy within ±2% under complex water quality conditions and possess a rapid response capability of less than 30 seconds. On the other hand, field monitoring stations and automated production lines increasingly require autonomous operation capabilities, necessitating dissolved oxygen electrodes with long-term stability and low maintenance characteristics to reduce calibration frequency and component replacement. Simultaneously, with the widespread application of online monitoring systems, electrode structures must adapt to different operating conditions and operate reliably under high pressure, high temperature, or chemical corrosion environments. Integration, modularization, and intelligence have become inevitable trends in industry development, requiring electrode structure design to not only consider the measurement principle itself but also ease of installation and maintenance, multi-parameter integration capabilities, and compatibility with digital systems, providing comprehensive and reliable technical support for water quality monitoring and industrial process control. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a polarographic dissolved oxygen electrode structure.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] Polarographic dissolved oxygen electrode structure includes:

[0008] Electrode connectors are used to output electrical signals;

[0009] The electrode core assembly includes a glass tube, platinum wire, anode silver cylinder, electrode core sealing ring, PT100 temperature sensor, and wire terminals; the platinum wire is fused through the glass tube to form the cathode; the PT100 temperature sensor is installed inside the anode silver cylinder;

[0010] The diaphragm assembly includes a pressure plate holder, a retaining ring, a fifth sealing ring, and a diaphragm; the pressure plate holder is connected to the retaining ring, and the diaphragm is installed between the pressure plate holder and the retaining ring; and

[0011] A connecting mechanism is used to connect the electrode connector, electrode core assembly, and diaphragm assembly into one unit; the connecting mechanism includes a connector sleeve, nut, sheath, sleeve, first sealing ring, electrode rod, sealing ring pressure ring, second sealing ring, adapter, third sealing ring, pressure ring, silicone sleeve, PEEK sleeve, fourth sealing ring, and electrode core sleeve.

[0012] Furthermore, the glass tube is a high borosilicate glass tube with a SiO2 content of not less than 80%, a B2O3 content of 12-13%, and a coefficient of thermal expansion of 3.3 × 10⁻⁶. -6 / K.

[0013] Furthermore, the diameter of the platinum wire is 0.2 mm, and the difference in the coefficients of thermal expansion between the platinum wire and the glass tube is less than 0.5 × 10⁻⁶. -6 / K.

[0014] Furthermore, the anode silver cylinder is made of silver material with a purity of Ag999, with a wall thickness of 0.8 mm, a height of 44.5 mm, and an inner diameter of 5 mm; the surface of the anode silver cylinder is treated with chlorination to form an Ag / AgCl reference system.

[0015] Furthermore, the surface chlorination treatment of the anode silver cylinder was carried out by electrolysis in a 0.1M HCl solution at a current density of 0.5 mA / cm². 2 .

[0016] Furthermore, the PT100 temperature sensor uses an alumina ceramic package with a thermal conductivity of 30 W / m·K; the PT100 temperature sensor is fixed inside the anode silver cylinder by potting with high-temperature resistant epoxy resin.

[0017] Furthermore, the glass transition temperature of the high-temperature resistant epoxy adhesive is 210℃, and its curing process is 120℃ / 2 hours + 150℃ / 4 hours.

[0018] Furthermore, the pressure plate holder is made of PEEK material with a heat distortion temperature of 315℃; the retaining ring is made of 316L stainless steel with dimensions of Φ10mm×5.5mm; the pressure plate holder and the retaining ring are connected by an interference fit.

[0019] Furthermore, the diaphragm is made of PTFE material with a thickness of 25μm; the fifth sealing ring is made of EPDM material with a hardness of 70±5 Shore A.

[0020] Furthermore, the electrode connector is an aviation plug conforming to the MIL-DTL-5015 standard; the insulator inside the connector sleeve is made of PEEK material with a volume resistivity greater than 10 Ω·cm. 16 Ω·cm; the first, second, third, and fourth sealing rings are arranged in a double-layer staggered pattern, with a compression of 25-30%.

[0021] The beneficial effects of this utility model are as follows:

[0022] The polarographic dissolved oxygen electrode structure of this invention adopts a design of high borosilicate glass fused to a platinum cathode wire, and uses a gradient annealing process to ensure that the difference in the coefficients of thermal expansion between the glass tube and the platinum wire is less than 0.5 × 10⁻⁶. -6 / K. This precise matching encapsulation technology significantly improves the reliability of the fusion-sealed interface, eliminates residual stress at the sealing interface, and effectively solves the problem of cracking and leakage of traditional electrodes under temperature fluctuation conditions, extending the service life of the electrodes by more than 2.5 times.

[0023] The silver anode of the Ag / AgCl reference system has been optimized and is made of Ag999 pure silver. Its 0.8mm thick structure, combined with a precisely controlled chlorination process, improves reference potential stability by 40%. Simultaneously, the flow field-optimized anode structure reduces the boundary layer thickness by 40% at a Reynolds number Re=120, significantly increasing the renewal rate of dissolved oxygen molecules on the membrane surface. This reduces the response time from 45-60 seconds in traditional products to no more than 30 seconds, greatly enhancing the sensitivity of monitoring changes in dissolved oxygen concentration in water.

[0024] This invention employs a PT100 temperature sensor encapsulated in alumina ceramic, with a thermal conductivity of 30 W / m·K, and is fixed in place with high-temperature resistant epoxy resin. This structural design ensures a 60% improvement in thermal coupling efficiency between the temperature sensor and the measured medium, and increases temperature measurement accuracy to ±0.1℃, a significant improvement over the traditional ±0.3-0.5℃. Precise temperature compensation keeps the measurement error of the electrode within ±2% in the 0-60℃ temperature range, meeting the requirements of high-precision industrial testing.

[0025] The diaphragm assembly employs an interference fit design between a PEEK pressure plate and a 316L stainless steel retaining ring, solving the problems of loosening and unreliable sealing inherent in traditional threaded connections. This structure ensures more uniform stress distribution on the diaphragm during operation, improving diaphragm deformation consistency by 85% and effectively eliminating measurement errors caused by uneven diaphragm deformation. Simultaneously, this design also simplifies diaphragm replacement, reducing the time from 8-10 minutes to 2-3 minutes, significantly lowering maintenance costs.

[0026] This invention employs a double-layered, staggered arrangement of EPDM sealing rings, with compression controlled within the optimal range of 25-30%, ensuring a complete seal for the electrode under pressures of 0-0.6 MPa. Compared to a single-layer seal, this multi-layered sealing structure increases the ultimate pressure withstand capability by 50% and reduces the seal failure rate by 75%, significantly improving the electrode's applicability under high pressure or pressure fluctuation environments.

[0027] The modular design allows for rapid replacement of core components within 3 minutes, significantly reducing time and cost of troubleshooting and parts replacement compared to traditional integrated structures. This design allows users to replace diaphragm assemblies of different specifications according to actual needs, making the same electrode suitable for applications with different measurement ranges and response speed requirements, thus improving the product's versatility and economy.

[0028] The selection of materials for each component has been systematically optimized. The use of PEEK material ensures the chemical stability of the electrode under complex water quality conditions; the application of 316L stainless steel enhances the mechanical strength of the structure; and the combined application of multiple high-performance sealing materials solves the problem of the electrode's adaptability to thermal expansion and contraction under different temperature conditions. This material compatibility design allows the electrode to operate for extended periods within a pH range of 2-12, with a 30% improvement in tolerance compared to conventional electrodes.

[0029] By employing innovative processes such as gradient annealing, precision chlorination, and high-temperature epoxy potting, the overall performance of the electrodes has been significantly improved. In practical application testing, the zero-point drift of the electrodes has been reduced from 0.8-1.2% / month in traditional products to 0.3-0.5% / month, significantly reducing the frequency of calibration and meeting the requirements for long-term stable operation of automated measurement systems.

[0030] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0031] Figure 1 This is an exploded view of the overall electrode structure of the polarographic dissolved oxygen electrode structure proposed in this utility model;

[0032] Figure 2 This is a cross-sectional schematic diagram of the electrode core structure of the polarographic dissolved oxygen electrode structure proposed in this utility model;

[0033] Figure 3 This is a cross-sectional schematic diagram of the membrane fixing structure of the polarographic dissolved oxygen electrode structure proposed in this utility model.

[0034] In the diagram: 1. Electrode connector; 2. Connector sleeve; 3. Nut; 4. Sheath; 5. Sleeve; 6. First sealing ring; 7. Electrode rod; 8. Sealing ring pressure ring; 9. Second sealing ring; 10. Adapter; 11. Electrode core assembly; 1101. Wire terminal; 1102. Anode silver tube; 1103. Electrode core sealing ring; 1104. PT100; 1105. Platinum wire; 1106. Glass tube; 12. Third sealing ring; 13. Pressure ring; 14. Silicone sleeve; 15. PEEK sleeve; 16. Diaphragm assembly; 1601. Diaphragm base; 1602. Fixing ring; 1603. Fifth sealing ring; 1604. Diaphragm; 17. Fourth sealing ring; 18. Electrode core sleeve. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0036] Electrode overall structure

[0037] like Figure 1 As shown, the polarographic dissolved oxygen electrode of this invention consists of the following main parts:

[0038] Electrode connector 1 serves as the electrical signal output terminal and is connected to the electrode body via connector sleeve 2 and nut 3. Sheath 4 protects the internal components and forms an external protective shell with sleeve 5. First sealing ring 6 is installed between sleeve and electrode rod 7 to ensure watertightness at the connection. Sealing ring pressure ring 8 applies pressure to second sealing ring 9, ensuring it fits tightly around adapter 10.

[0039] The electrode core assembly 11 is the core component of this invention, containing the key electrochemical elements required for measurement. A third sealing ring 12 cooperates with a pressure ring 13 to secure the electrode core assembly in place. A silicone sleeve 14 provides additional waterproof protection, while a PEEK sleeve 15 serves for insulation and mechanical support.

[0040] The diaphragm assembly 16 is located at the front end of the electrode and consists of a diaphragm holder 1601, a retaining ring 1602, a fifth sealing ring 1603, and a diaphragm 1604. The fourth sealing ring 17 is installed between the diaphragm assembly and the electrode core sleeve 18 to form a complete sealing system.

[0041] Each component adopts a modular design for easy assembly and maintenance. During assembly, follow... Figure 1 The components are installed sequentially according to the serial numbers marked on the label, and finally fixed with threaded connections.

[0042] Electrode core assembly structure

[0043] like Figure 2 As shown, the electrode core assembly 11 includes the following components:

[0044] Wire terminal 1101 is used for electrical connection and is connected to external cables by soldering. The anode silver cylinder 1102 is made of Ag999 pure silver, with a wall thickness of 0.8 mm, a height of 44.5 mm, and an inner diameter of 5 mm. Its surface is chlorinated and electrolyzed in a 0.1 M HCl solution at a current density of 0.5 mA / cm². 2 An Ag / AgCl reference system is formed.

[0045] The core sealing ring 1103 ensures a seal between the anode silver cylinder and the PT100 temperature sensor 1104. The PT100 sensor uses an alumina ceramic package with a thermal conductivity of 30 W / m·K to ensure accurate temperature measurement.

[0046] Platinum wire 1105, with a diameter of 0.2 mm, is used as the cathode and encapsulated in a high borosilicate glass tube 1106. The glass tube material contains ≥80% SiO2 and 12-13% B2O3, with a coefficient of thermal expansion α = 3.3 × 10⁻⁶. -6 / K, matching the coefficient of thermal expansion of platinum wire, with a difference of <0.5×10. -6 / K ensures long-term stable sealing performance.

[0047] Diaphragm fixing structure

[0048] like Figure 3 As shown, the diaphragm assembly 16 employs an innovative fixing structure:

[0049] The pressure plate holder 1601 is made of PEEK material, Victrex 450G, with a heat distortion temperature (HDT) of 315℃, exhibiting excellent chemical stability and mechanical strength. The retaining ring 1602 is made of 316L stainless steel, with dimensions of Φ10mm × 5.5mm, and is connected to the pressure plate holder with an interference fit.

[0050] A fifth sealing ring 1603 is installed inside the pressure vessel, providing additional sealing protection. A diaphragm 1604 is installed between the pressure vessel and the retaining ring, and is securely fixed by the tight fit between the two. The diaphragm is made of PTFE material with a thickness of 25 μm, exhibiting excellent oxygen permeability and chemical stability.

[0051] Example

[0052] Example 1: Standard Dissolved Oxygen Electrode

[0053] The dissolved oxygen electrode in this embodiment is suitable for routine water quality testing, and its specific parameters are as follows:

[0054] Electrode dimensions: Total length: 180mm; Outer diameter: 12mm; Threaded connection: M12×1.5.

[0055] Electrode core assembly:

[0056] Cathode material: Φ0.2mm platinum wire; Anode material: Ag999 pure silver tube, wall thickness 0.8mm; Reference system: Ag / AgCl, potential approximately +197mV (vs. SHE); Temperature sensor: PT100, accuracy ±0.1℃.

[0057] Diaphragm assembly:

[0058] Membrane material: PTFE, thickness 25μm; effective membrane area: 28mm² 2 Sealing ring material: EPDM, hardness 70±5 Shore A.

[0059] Connection system:

[0060] Connector type: 3-pin aviation connector, MIL-DTL-5015 standard;

[0061] Insulating material: PEEK, volume resistivity >10 16 Ω·cm;

[0062] Performance parameters: Measurement range: 0-20 mg / L; Response time: <30 seconds; Drift: <0.5% / month; Operating temperature: 0-60℃; Pressure range: 0-0.6 MPa;

[0063] The assembly process is as follows: First, the platinum wire 1105 is fused and sealed through a borosilicate glass tube 1106, and then subjected to gradient annealing, cooling from 580℃ to 300℃ at a rate of 2℃ / min to eliminate thermal stress. Then, the PT100 temperature sensor 1104 and the electrode core sealing ring 1103 are installed into the anode silver cylinder 1102, and encapsulated with high-temperature resistant epoxy resin EP42HT-2, cured according to a process of 120℃ / 2h + 150℃ / 4h.

[0064] The assembled electrode core assembly 11 is then placed with other components... Figure 1 Assemble the components as shown. Before assembly, the diaphragm 1604 needs to be soaked in the electrolyte for 30 minutes, and then installed between the pressure plate seat 1601 and the retaining ring 1602. Finally, check the compression of each sealing ring to ensure it is within the range of 25-30% to guarantee good sealing performance.

[0065] Example 2: Miniature Dissolved Oxygen Electrode

[0066] The dissolved oxygen electrode of this embodiment is suitable for space-constrained applications, such as inside a bioreactor or a microfluidic system. Its specific parameters are as follows:

[0067] Electrode dimensions: Total length: 120mm; Outer diameter: 8mm; Threaded connection: M8×1.0;

[0068] Electrode core assembly: Cathode material: Φ0.1mm platinum wire; Anode material: Ag999 pure silver tube, wall thickness 0.5mm; Reference system: Ag / AgCl; Temperature sensor: Miniature PT100, accuracy ±0.2℃.

[0069] Membrane assembly: Membrane material: PTFE, thickness 15μm; Effective membrane area: 12mm² 2 Sealing ring material: FKM, hardness 75±5 Shore A;

[0070] Connection System

[0071] Connector type: Miniature 4-pin connector;

[0072] Insulation material: PEEK;

[0073] Performance parameters: Measurement range: 0-20 mg / L; Response time: <45 seconds; Drift: <0.8% / month; Operating temperature: 0-50℃; Pressure range: 0-0.4 MPa.

[0074] The assembly process is basically the same as in Example 1, but the dimensions of key components have been miniaturized and the diaphragm fixing structure has been optimized. Threaded fastening is used instead of interference fit, which facilitates assembly and maintenance in a confined space.

[0075] Example 3: High-voltage dissolved oxygen electrode

[0076] The dissolved oxygen electrode of this embodiment is suitable for measurement under high pressure environments, such as deep-sea water quality monitoring or high-pressure reactors. Its specific parameters are as follows:

[0077] Electrode dimensions: Total length: 220mm; Outer diameter: 18mm; Threaded connection: M18×1.5.

[0078] Electrode core assembly: Cathode material: Φ0.3mm platinum wire; Anode material: Ag999 pure silver tube, wall thickness 1.2mm; Reference system: Ag / AgCl; Temperature sensor: High-voltage PT100, accuracy ±0.1℃.

[0079] Membrane assembly: Membrane material: modified PTFE, thickness 35μm; Effective membrane area: 38mm² 2 Sealing ring material: fluororubber, hardness 80±5 Shore A;

[0080] Connection system: Connector type: High-voltage waterproof 5-pin connector; Insulation material: PEEK.

[0081] Performance parameters: Measurement range: 0-50 mg / L; Response time: <40 seconds; Drift: <0.3% / month; Operating temperature: 0-80℃; Pressure range: 0-2.0 MPa.

[0082] The assembly process was improved based on Example 1, particularly in the sealing system, which employed a multi-seal structure including three staggered O-rings and a flat sealing gasket to ensure stability under high pressure. The glass sealing portion of the electrode core assembly features a reinforced design, with the glass wall thickness increased to 1.5 mm. An improved annealing process was used, slowly reducing the temperature from 600°C to 300°C at a rate of 1°C / min, and then to room temperature at a rate of 0.5°C / min to completely eliminate residual stress.

[0083] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A polarographic dissolved oxygen electrode structure, characterized in that, include: Electrode connector (1), used for outputting electrical signals; The electrode core assembly (11) includes a glass tube (1106), a platinum wire (1105), an anode silver cylinder (1102), an electrode core sealing ring (1103), a PT100 temperature sensor (1104), and wire terminals (1101); the platinum wire (1105) is fused together with the glass tube (1106) to form a cathode; the PT100 temperature sensor (1104) is disposed inside the anode silver cylinder (1102); A diaphragm assembly (16) includes a pressure plate (1601), a retaining ring (1602), a fifth sealing ring (1603), and a diaphragm (1604); the pressure plate (1601) is connected to the retaining ring (1602), and the diaphragm (1604) is installed between the pressure plate (1601) and the retaining ring (1602); and A connecting mechanism is used to connect the electrode connector (1), the electrode core assembly (11), and the diaphragm assembly (16) into a whole; the connecting mechanism includes a connector sleeve (2), a nut (3), a sheath (4), a sleeve (5), a first sealing ring (6), an electrode rod (7), a sealing ring pressure ring (8), a second sealing ring (9), an adapter (10), a third sealing ring (12), a pressure ring (13), a silicone sleeve (14), a PEEK sleeve (15), a fourth sealing ring (17), and an electrode core sleeve (18).

2. The polarographic dissolved oxygen electrode structure according to claim 1, characterized in that, The glass tube (1106) is a high borosilicate glass tube with a SiO2 content of not less than 80%, a B2O3 content of 12-13%, and a coefficient of thermal expansion of 3.3 × 10⁻⁶. -6 / K.

3. The polarographic dissolved oxygen electrode structure according to claim 1, characterized in that, The platinum wire (1105) has a diameter of 0.2 mm, and the difference in the coefficient of thermal expansion between the platinum wire (1105) and the glass tube (1106) is less than 0.5 × 10⁻⁶. -6 / K.

4. The polarographic dissolved oxygen electrode structure according to claim 1, characterized in that, The anode silver cylinder (1102) is made of silver material with a purity of Ag999, with a wall thickness of 0.8 mm, a height of 44.5 mm, and an inner diameter of 5 mm; the surface of the anode silver cylinder (1102) is treated with chlorination to form an Ag / AgCl reference system.

5. The polarographic dissolved oxygen electrode structure according to claim 4, characterized in that, The surface chlorination treatment of the anode silver cylinder (1102) was carried out by electrolysis in a 0.1M HCl solution at a current density of 0.5 mA / cm². 2 .

6. The polarographic dissolved oxygen electrode structure according to claim 1, characterized in that, The PT100 temperature sensor (1104) is encapsulated in alumina ceramic with a thermal conductivity of 30 W / m·K. The PT100 temperature sensor (1104) is fixed inside the anode silver cylinder (1102) by potting with high-temperature resistant epoxy resin.

7. The polarographic dissolved oxygen electrode structure according to claim 6, characterized in that, The glass transition temperature of the high-temperature resistant epoxy adhesive is 210℃, and its curing process is 120℃ / 2 hours + 150℃ / 4 hours.

8. The polarographic dissolved oxygen electrode structure according to claim 1, characterized in that, The pressing base (1601) is made of PEEK material with a heat distortion temperature of 315℃; the fixing ring (1602) is made of 316L stainless steel with a size of Φ10mm×5.5mm; the pressing base (1601) and the fixing ring (1602) are connected by an interference fit.

9. The polarographic dissolved oxygen electrode structure according to claim 1, characterized in that, The diaphragm (1604) is made of PTFE material with a thickness of 25 μm; the fifth sealing ring (1603) is made of EPDM material with a hardness of 70±5 Shore A.

10. The polarographic dissolved oxygen electrode structure according to claim 1, characterized in that, The electrode connector (1) is an aviation connector conforming to the MIL-DTL-5015 standard; the insulator inside the connector sleeve (2) is made of PEEK material with a volume resistivity greater than 10. 16 Ω·cm; the first sealing ring (6), the second sealing ring (9), the third sealing ring (12) and the fourth sealing ring (17) are arranged in a double-layer staggered manner, and the compression amount is 25-30%.

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