Resistor disc electrode and application thereof

Abstract

The invention discloses a resistor disc electrode and application thereof, and belongs to the technical field of manufacturing of electronic functional materials and power equipment. The resistor disc electrode is prepared by printing and coating base metal electrode slurry on the end face of a resistor disc through a silk screen or a stainless steel screen, and then sequentially performing drying and high-temperature sintering. The temperature of the high-temperature sintering is 450 DEG C to 550 DEG C. The resistor disc electrode is compact in structure (low in porosity), high in adhesive force, uniform in thickness, high in material utilization rate and excellent in electrical performance. When the resistor disc electrode is applied to the lightning arrester, the repeated charge transfer capacity and the large-current impact tolerance performance of the lightning arrester can be remarkably improved, and the resistor disc electrode is suitable for large-scale intelligent manufacturing of the high-performance lightning arrester.

Description

Technical Field

[0001] This invention relates to the field of electronic functional materials and power equipment manufacturing technology, and in particular to a resistive electrode and its application. Background Technology

[0002] Surge arresters, as crucial overvoltage protection devices in power systems, rely on zinc oxide resistive elements as their core component. Conductive electrodes must be fabricated at both ends of the resistive element to ensure good electrical contact and current conduction. Currently, arc spraying technology is widely used in industry, where aluminum wire is sprayed onto the two end faces of the resistive element to form metal electrodes. However, traditional arc spraying processes have the following technical drawbacks:

[0003] Poor adhesion: During the spraying process, metal particles impact the substrate surface at high speed, and the bonding mainly relies on mechanical interlocking. The interfacial bonding strength is low, and the electrode is prone to detachment under high current impact or thermal cycling conditions.

[0004] High porosity: The coating layer contains many micropores and voids, which leads to a decrease in the conductivity of the electrodes and affects the reliability of the device;

[0005] Poor thickness uniformity: Affected by the speed, distance and angle of the spray gun, the electrode thickness distribution is uneven, which affects the overall consistency of the electric field distribution.

[0006] Low material utilization: During the arc spraying process, a large amount of metal is atomized and scattered, and only about 13% of the material is actually deposited on the surface of the workpiece, resulting in serious waste of resources and environmental pollution.

[0007] Therefore, researching and developing a high-efficiency, stable, environmentally friendly, and high-performance resistive electrode has become a pressing technical challenge in this field. Summary of the Invention

[0008] In view of this, the technical problem to be solved by the present invention is to provide a resistive sheet electrode and its application. The resistive sheet electrode has a dense structure (low porosity), high adhesion, uniform thickness, high material utilization, and excellent electrical performance.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] This invention provides a resistive electrode, which is prepared by coating a base metal electrode paste onto the end face of a resistive sheet via screen printing or stainless steel mesh, followed by drying and high-temperature sintering.

[0011] This invention combines screen printing or stainless steel mesh printing with high-temperature sintering to enable diffusion and interfacial reactions between metal particles and between the metal and the resistive substrate, forming a metallurgical bond. This significantly improves the adhesion between the base metal electrode and the resistive substrate, effectively preventing electrode peeling.

[0012] Preferably, the high-temperature sintering temperature is 450℃~550℃; more preferably, it is 480℃~550℃; and even more preferably, it is 480℃~520℃.

[0013] After the screen or stainless steel mesh printing process, by adjusting the sintering temperature, the electrode layer of the resistive sheet electrode described in this invention is made highly dense, with a porosity of less than 5%, which is far superior to the 15%~30% of the arc spraying process. This reduces the contact resistance of the resistive sheet electrode and improves the current carrying capacity of the resistive sheet.

[0014] After high-temperature sintering, the metal electrode layer is naturally cooled to room temperature to obtain a metal electrode layer that is tightly bonded to the end face of the resistor sheet, which is the resistor sheet electrode.

[0015] This invention employs screen printing or stainless steel mesh printing to precisely control the coating thickness and flatness. The thickness deviation of the electrodes at both ends of the same resistor sheet is less than ±10%, resulting in good consistency between different batches and improving product batch stability. Furthermore, the directional and quantitative coating through screen printing or stainless steel mesh printing minimizes the splashing loss of base metal electrode paste, achieving an electrode material utilization rate of over 95%. This represents a fundamental leap in utilization rate compared to arc spraying, significantly reducing costs and environmental pollution.

[0016] The present invention uniformly coats a base metal electrode paste onto the two end faces of a resistor substrate using a screen printing or stainless steel screen printing process to form a predetermined pattern and a wet film layer of a certain thickness.

[0017] Preferably, the conditions for screen printing or stainless steel mesh printing in this invention are as follows:

[0018] The mesh count of the wire mesh or stainless steel mesh is 100~300.

[0019] The printing is done 1 to 2 times, and the dry film thickness obtained from a single printing is controlled to be 10 to 50 μm.

[0020] More preferably, the mesh count of the wire mesh or stainless steel mesh is 150 to 300.

[0021] More preferably, the dry film thickness obtained by a single printing is controlled to be 10~15 μm.

[0022] Preferably, after obtaining a wet film by screen printing or stainless steel screen printing, the resistive sheet coated with the wet film is dried to remove the organic solvent in the base metal electrode paste, thereby forming a pre-cured electrode film layer.

[0023] Preferably, the drying temperature is 80℃~120℃; more preferably, it is 100℃~120℃.

[0024] Preferably, the drying time is 10-30 min; more preferably, it is 10-20 min.

[0025] Preferably, the high-temperature sintering of the present invention is carried out in an air atmosphere;

[0026] Preferably, the heating rate of the high-temperature sintering is 3~5℃ / min; more preferably, it is 3.5~4.5℃ / min.

[0027] The holding time for the high-temperature sintering is 5 to 15 minutes; more preferably 15 minutes.

[0028] This invention combines screen printing or stainless steel mesh printing with high-temperature sintering, making the preparation of the resistive electrode sheet easy to integrate into an automated production line, enabling continuous, mass production, significantly improving production efficiency, and meeting the needs of modern smart factories.

[0029] Preferably, the base metal electrode paste of the present invention is selected from aluminum paste, zinc paste or copper paste; more preferably, it is aluminum paste or copper paste.

[0030] The resistor sheet described in this invention is selected from metal oxide resistor sheets or linear resistor sheets.

[0031] Preferably, the resistor sheet is selected from zinc oxide resistor sheet or alumina ceramic resistor sheet; more preferably, it is a zinc oxide resistor sheet.

[0032] The zinc oxide resistor is selected from zinc oxide resistors for surge arresters or zinc oxide resistors for surge protection devices (SPDs).

[0033] The alumina ceramic resistor is a linear resistor.

[0034] The present invention coats the base metal electrode paste onto the end face of the resistor sheet to form a conductive electrode.

[0035] Preferably, the aluminum paste of the present invention is composed of aluminum powder, organic carrier and glass flux;

[0036] The organic carrier comprises a film-forming resin, a solvent, and a rheology modifier.

[0037] More preferably, the aluminum powder has an average particle size of 0.5~5 μm; more preferably, it has an average particle size of 1.5~3 μm.

[0038] More preferably, the purity of the aluminum powder is ≥99%.

[0039] Preferably, the film-forming resin of the present invention is selected from ethyl cellulose resin or acrylic resin; more preferably, it is ethyl cellulose resin.

[0040] Preferably, the solvent is selected from terpineol solvent or diethylene glycol ether acetate; more preferably, it is terpineol solvent.

[0041] Preferably, the rheology modifier is selected from terpene alcohols.

[0042] The glass flux described in this invention is used to promote the interfacial reaction between the metal and the resistor substrate during high-temperature sintering.

[0043] Preferably, the glass flux of the present invention is selected from borosilicate glass powder.

[0044] The present invention also provides the application of the above-mentioned resistive electrode in a surge arrester.

[0045] When the resistive electrode described in this invention is applied to a surge arrester, the surge arrester exhibits superior charge transfer capability and thermal stability in repeated action load tests. Furthermore, no electrode cracking or peeling was observed in the high current impulse (e.g., 4 / 10μs waveform, 100 kA) test, and its energy absorption capacity and withstand cycles are significantly better than those of products made with traditional processes.

[0046] Compared with existing technologies, the resistive electrode provided by this invention is prepared by coating a base metal electrode paste onto the end face of a resistive sheet via screen printing or stainless steel mesh, followed by drying and high-temperature sintering; the high-temperature sintering temperature is 450℃~550℃. The resistive electrode has a dense structure (low porosity), high adhesion, uniform thickness, high material utilization, and excellent electrical performance. Applying this resistive electrode to surge arresters can significantly improve the arrester's ability to repeatedly transfer charge and withstand high-current impulses, making it suitable for large-scale intelligent manufacturing of high-performance surge arresters and showing promising application prospects. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the process flow of the present invention;

[0048] Figure 2 The images show a comparison of the cross-sectional SEM images of the electrodes prepared by arc spraying in Comparative Example 1 and stainless steel mesh printing in Example 1. Detailed Implementation

[0049] To further illustrate the present invention, the resistive electrode provided by the present invention and its application are described in detail below with reference to embodiments.

[0050] Example 1

[0051] Preparation and performance testing of aluminum paste electrodes of the present invention

[0052] (a) Preparation

[0053] Take 94.5 wt% of spherical aluminum powder (purity ≥99%) with an average particle size of 2 μm, add 2.5 wt% ethyl cellulose resin, 1.5 wt% terpineol solvent, 0.5 wt% terpene alcohol, and 1.0 wt% borosilicate glass powder, and mix them in a planetary mixer for 6 hours to prepare a uniform aluminum paste.

[0054] Using a 300-mesh stainless steel mesh, aluminum paste cooled to room temperature was double-sided printed onto the end face of a zinc oxide resistive sheet with dimensions of Φ45×30 mm under a pressure of 0.3 MPa. Printing was performed once, with the dry film thickness controlled to 10 μm per print. After each print, the sheet was baked at 120℃ for 15 minutes to form a pre-cured electrode film. The sheet was then placed in a sintering furnace, where the temperature was increased to 520℃ at a rate of 4℃ / min and held for 15 minutes. This allowed the aluminum particles to fully densify and undergo interfacial diffusion and partial chemical bonding with the zinc oxide ceramic matrix, forming a strong metallurgical bond. Finally, the sheet was allowed to cool naturally, resulting in a metal electrode layer tightly bonded to the end face of the resistive sheet, completing the electrode fabrication.

[0055] (II) Test Results

[0056] Adhesion: 6000~7000 N (determined according to GB / T 5210 pull-out method);

[0057] Thickness uniformity: deviation 0.02 mm; (thickness difference at five points: east, west, south, north, and center, measured by altimeter)

[0058] Material utilization rate: 96% as measured;

[0059] Porosity: <5%.

[0060] Example 2

[0061] Preparation and performance testing of aluminum paste electrodes of the present invention

[0062] (a) Preparation

[0063] Take 94.5 wt% of spherical aluminum powder (purity ≥99%) with an average particle size of 2 μm, add 2.5 wt% ethyl cellulose resin, 1.5 wt% terpineol solvent, 0.5 wt% terpene alcohol, and 1.0 wt% borosilicate glass powder, and mix them in a planetary mixer for 6 hours to prepare a uniform aluminum paste.

[0064] Using a 200-mesh stainless steel mesh, aluminum paste cooled to room temperature was double-sided printed onto the end face of a zinc oxide resistive sheet with dimensions of Φ45×30 mm under a pressure of 0.3 MPa. Printing was performed once, with the dry film thickness controlled to 15 μm for each print. After each print, the sheet was baked at 120℃ for 15 minutes to form a pre-cured electrode film. Subsequently, the sheet was placed in a sintering furnace, where the temperature was increased to 520℃ at a rate of 4℃ / min and held for 15 minutes to fully densify the aluminum particles and allow them to diffuse interfacially and partially chemically bond with the zinc oxide ceramic matrix, forming a strong metallurgical bond. Finally, the sheet was allowed to cool naturally, resulting in a metal electrode layer tightly bonded to the end face of the resistive sheet, completing the electrode fabrication.

[0065] (II) Test Results

[0066] Adhesion: 8000~9000 N (determined according to GB / T 5210 pull-out method);

[0067] Thickness uniformity: deviation 0.02 mm; (thickness difference at five points: east, west, south, north, and center, measured by altimeter)

[0068] Material utilization rate: 96% as measured;

[0069] Porosity: <5%.

[0070] Example 3

[0071] Preparation and performance testing of aluminum paste electrodes of the present invention

[0072] (a) Preparation

[0073] Take 94.5 wt% of spherical aluminum powder (purity ≥99%) with an average particle size of 2 μm, add 2.5 wt% ethyl cellulose resin, 1.5 wt% terpineol solvent, 0.5 wt% terpene alcohol, and 1.0 wt% borosilicate glass powder, and mix them in a planetary mixer for 6 hours to prepare a uniform aluminum paste.

[0074] Using a 100-mesh stainless steel mesh, aluminum paste cooled to room temperature was double-sided printed onto the end face of a zinc oxide resistive sheet with dimensions of Φ45×30 mm under a pressure of 0.3 MPa. Printing was performed once, with the dry film thickness controlled to 25 μm for each print. After each print, the sheet was baked at 120℃ for 15 minutes to form a pre-cured electrode film. Subsequently, the sheet was placed in a sintering furnace, where the temperature was increased to 520℃ at a rate of 4℃ / min and held for 15 minutes to fully densify the aluminum particles and allow interfacial diffusion and partial chemical bonding with the zinc oxide ceramic matrix, forming a strong metallurgical bond. Finally, the sheet was allowed to cool naturally, resulting in a metal electrode layer tightly bonded to the end face of the resistive sheet, completing the electrode fabrication.

[0075] (II) Test Results

[0076] Adhesion: 9000~10000 N (determined according to GB / T 5210 pull-out method);

[0077] Thickness uniformity: deviation 0.03 mm; (thickness difference at five points: east, west, south, north, and center, measured by altimeter)

[0078] Material utilization rate: 96% as measured;

[0079] Porosity: <5%.

[0080] Comparative Example (Preparation of Aluminum Electrodes by Arc Spraying)

[0081] (a) Preparation

[0082] The same resistance element as in Example 1 (i.e., a zinc oxide resistance element with a diameter of 45×30 mm) was used, and φ1.6 mm aluminum wire was used for arc spraying. The parameters were: voltage 28 V and current 100 A.

[0083] (II) Test Results

[0084] Adhesion: 2000~3000 N (determined according to GB / T 5210 pull-out method);

[0085] Thickness uniformity: deviation 0.06 mm; (thickness difference at five points: east, west, south, north, and center, measured by altimeter)

[0086] Material utilization rate: 12% as measured;

[0087] Porosity: >35%.

[0088] The performance test results of the resistive sheet electrodes prepared in Examples 1-3 and the comparative examples are shown in Table 1.

[0089] Table 1 Performance test results of the resistive sheet electrodes prepared in Examples 1-3 and the comparative examples

[0090] Example 1 Example 2 Example 3 Comparative Example Adhesion / N 6000~7000 8000~9000 9000~10000 2000~3000 Thickness uniformity deviation / mm 0.02 0.02 0.03 0.06 Material utilization rate / % 96 96 96 12 Porosity / % ＜5 ＜5 ＜5 ＞35 10 kA lightning residual voltage ratio 1.71 1.71 1.71 1.76 4 / 10 μs high current surge / kA 110 120 115 100 2 ms repetitive charge transfer capability / Qrs 1.2C 1.3C 1.3C 1.2C

[0091] Comparing the test results of Examples 1-3 and the comparative examples, the results show that the resistance sheet electrodes prepared in Examples 1-3 of this invention have significantly better adhesion and material utilization than the resistance sheet electrodes prepared in the comparative examples. Furthermore, the resistance sheet electrodes of Examples 1-3 have more uniform thickness and better electrical performance. Specifically, the resistance sheet electrode prepared in Example 2 has four times the electrode adhesion of the resistance sheet electrode prepared in the comparative example, effectively preventing electrode peeling. Moreover, the resistance sheet electrode of Example 2 has more uniform thickness, higher material utilization, a denser electrode structure (lower porosity), and better electrical performance than the resistance sheet electrode of the comparative example.

[0092] Figure 2The images show a comparison of cross-sectional micrographs of electrodes prepared by arc spraying (a comparative example of the present invention) and stainless steel mesh printing (a comparative example of the present invention). The results show that the electrodes prepared by the method described in the present invention (screen printing or stainless steel mesh printing) have a significantly higher degree of structural density than the electrodes prepared by arc spraying (a comparative example).

[0093] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A resistive electrode, characterized in that, It is prepared by coating the end face of the resistor sheet with base metal electrode paste through screen printing or stainless steel screen printing, followed by drying and high-temperature sintering. The high-temperature sintering temperature is 450℃~550℃.

2. The resistive electrode according to claim 1, characterized in that, The conditions for screen or stainless steel mesh printing are as follows: The mesh count of the wire mesh or stainless steel mesh is 100~300. The printing is done 1 to 2 times, and the dry film thickness obtained from a single printing is controlled to be 10 to 50 μm.

3. The resistive electrode according to claim 1, characterized in that, The drying temperature is 80℃~120℃; The drying time is 10-30 minutes.

4. The resistive electrode according to claim 1, characterized in that, The high-temperature sintering is carried out in an air atmosphere; The heating rate for the high-temperature sintering is 3~5℃ / min; The holding time for the high-temperature sintering is 5 to 15 minutes.

5. The resistive electrode according to claim 1, characterized in that, The base metal electrode paste is selected from aluminum paste, zinc paste, or copper paste; The resistor element is selected from zinc oxide resistor elements or alumina ceramic resistor elements.

6. The resistive electrode according to claim 5, characterized in that, The aluminum paste is composed of aluminum powder, an organic carrier, and a glass flux; The organic carrier comprises a film-forming resin, a solvent, and a rheology modifier.

7. The resistive electrode according to claim 6, characterized in that, The aluminum powder has an average particle size of 0.5~5 μm; The purity of the aluminum powder is ≥99%.

8. The resistive electrode according to claim 6, characterized in that, The film-forming resin is selected from ethyl cellulose resin or acrylic resin; The solvent is selected from terpineol solvent or diethylene glycol ether acetate; The rheology modifier is selected from terpene alcohols.

9. The resistive electrode according to claim 6, characterized in that, The glass flux is selected from borosilicate glass powder.

10. The application of the resistive electrode according to any one of claims 1 to 9 in a surge arrester.

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