CN108948400B - Method for improving flashover strength of vacuum edge surface of insulating material - Google Patents
Method for improving flashover strength of vacuum edge surface of insulating material Download PDFInfo
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- CN108948400B CN108948400B CN201810601970.5A CN201810601970A CN108948400B CN 108948400 B CN108948400 B CN 108948400B CN 201810601970 A CN201810601970 A CN 201810601970A CN 108948400 B CN108948400 B CN 108948400B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
- C08J7/12—Chemical modification
- C08J7/14—Chemical modification with acids, their salts or anhydrides
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
- C08J7/12—Chemical modification
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2323/04—Homopolymers or copolymers of ethene
- C08J2323/06—Polyethene
Abstract
The invention discloses a method for improving vacuum surface flashover strength of an insulating material. The method provided by the invention can obviously improve the vacuum surface flashover voltage of the insulating medium material, and has the advantages of simple realization, good practicability, simple and easily obtained required equipment and processing conditions and strong repeatability.
Description
Technical Field
The invention belongs to the technical field of high-voltage insulating materials, and particularly relates to a method for improving the flashover strength of an insulating material along a vacuum surface.
Background
The vacuum medium has the characteristics of high breakdown field strength and light weight, and is widely applied to the electric equipment, so that the volume and the weight of the electric equipment are greatly reduced, and the electric equipment is favorably developed towards high power density and miniaturization. Solid insulation elements are also essential in electrical equipment, and they serve for fixation, support and protection. However, the surface flashover phenomenon occurring at the interface of the vacuum and solid insulating medium can cause the failure of power equipment, cause serious safety accidents and cause huge economic loss, and becomes one of the main factors restricting the development of the power grid towards high voltage, large current and high capacity. Therefore, it is very important to research the flashover phenomenon and the forming mechanism of the insulating material along the surface so as to find a method for improving the flashover voltage along the surface. Known main factors influencing the flashover voltage along the surface of the insulating material are applied voltage waveform, the geometry of the insulating material, the surface treatment of the insulating material, the dielectric constant of the insulating material, the nano or micro doping of the insulating material, the pre-electricity-proof treatment of the insulating material, the multi-layer gradient insulating technology and the like, wherein the flashover voltage along the surface of the insulating material is improved by the surface treatment of the insulating material, which is a common method.
Dopamine has strong adhesion capability, can be closely combined with the surface of any solid material, and is widely applied to the fields of biological adhesives, separation membranes, sensors, biomedicine and the like. Dopamine also has strong reducing ability, which makes it possible to reduce metal ions into nanometer-sized metal particles attached to the surface of the material. The nano-sized metal particles are attached to the surface of the insulating material and can be used as deep traps to capture injected charges, so that the distortion of an electric field is inhibited, the charge recombination and the hot electron effect are reduced, and the surface flashover voltage is improved.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a method for improving the vacuum surface flashover strength of an insulating material aiming at the defects in the prior art, which can obviously improve the vacuum surface flashover voltage of the insulating medium material and has the advantages of simple realization, good practicability, simple and easily obtained required equipment and processing conditions and strong repeatability.
The invention adopts the following technical scheme:
a method for improving vacuum surface flashover strength of an insulating material comprises the steps of sequentially soaking an insulating medium material which is cleaned and dried in a dopamine solution, a silver nitrate solution and a dopamine solution at room temperature to prepare the insulating material with a dopamine-nano silver-dopamine sandwich structure on the surface.
Specifically, the method comprises the following steps:
s1, ultrasonically cleaning the insulating medium material by using absolute ethyl alcohol and deionized water in sequence, and then drying the insulating medium material in a vacuum drying oven;
s2, immersing the insulating medium material in the dopamine solution to enable the surface of the insulating medium material to adsorb a layer of dopamine;
s3, immersing the insulating material with dopamine adsorbed on the surface in a silver nitrate solution, reducing silver ions in the solution into nano silver particles under the action of the dopamine, and adsorbing the nano silver particles on the surface of the insulating material to form a dopamine-nano silver two-layer structure on the surface of the insulating material;
and S4, immersing the insulating material with the two-layer structure in the dopamine solution again to obtain the insulating material with the dopamine-nano silver-dopamine sandwich structure on the surface.
Further, in step S1, the drying temperature is 50-60 ℃ and the time is more than 24 h.
Further, in step S2, the concentration of the dopamine solution is 2g/L, and the soaking time at room temperature is 6-25 h.
Further, in step S3, the silver nitrate solution with a concentration of 50mmol/L is soaked at room temperature for 0-4 h.
Further, in step S4, the concentration of the dopamine solution is 2g/L, and the soaking time at room temperature is 6-25 h.
Furthermore, the insulating medium material is a low-density polyethylene film and is prepared by a hot pressing method.
Compared with the prior art, the invention has at least the following beneficial effects:
the invention relates to a method for improving vacuum surface flashover strength of an insulating material, which adopts a surface treatment method to improve the vacuum surface flashover strength of the insulating material, dopamine has strong adhesion and reduction performance at the same time, metal ions can be reduced into nanoparticles which are tightly combined with the surface of the insulating material, and a dopamine-nano silver-dopamine sandwich structure is formed on the surface of the insulating material through surface treatment, so that the surface conductivity and surface trap parameters of a sample are changed, the surface conductivity of the treated insulating material is obviously improved, the depth of a surface trap is increased, and the vacuum surface flashover voltage of the insulating material is improved under the combined action of the changes.
Further, when the low-density polyethylene is sequentially soaked in the dopamine solution, the silver nitrate solution and the dopamine solution for 4 hours, 2 hours and 24 hours, the vacuum direct-current surface flashover voltage of the sample with the dopamine-nano silver-dopamine sandwich structure on the surface is improved by 53 percent compared with that of untreated low-density polyethylene.
Furthermore, due to its excellent electrical, mechanical and thermodynamic properties, it is widely used in the field of electrical insulation, being the main insulating material of power cables. Although it is rarely applied to a vacuum environment and a flashover along the surface rarely occurs in practical applications, it can be used as a representative of polymer insulating materials for studying electrical properties of polymer dielectrics; in addition, the surface flashover performance of the dielectric is closely related to the breakdown performance, the surface modification is carried out on the low-density polyethylene to improve the surface flashover performance of the low-density polyethylene, the breakdown characteristic of the low-density polyethylene can be possibly improved, and a new thought is provided for solving the breakdown problem in the actual operation of the cable.
In conclusion, the method provided by the invention can obviously improve the vacuum surface flashover voltage of the insulating dielectric material, and has the advantages of simple realization, good practicability, simple and easily obtained required equipment and processing conditions and strong repeatability.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is a flow chart of the surface treatment of an insulating material;
FIG. 2 is a schematic surface topography observed by scanning electron microscope of a low density polyethylene sample before and after being treated by the method of the present invention, wherein (a) is untreated low density polyethylene, and (b) is low density polyethylene immersed in dopamine, silver nitrate and dopamine solutions for 4h, 2h and 24h, respectively.
Detailed Description
The invention provides a method for improving vacuum surface flashover strength of an insulating material. The dopamine-nano silver-dopamine sandwich structure is formed on the surface of the insulating material through surface treatment, the surface conductivity and the surface trap parameters of the sample are changed, and the creeping flashover strength of the sample is adjusted or improved under the combined action of the two parameters.
Referring to fig. 1, the method for improving the flashover strength of the vacuum edge surface of the insulating material of the present invention includes the following steps:
s1, ultrasonically cleaning the insulating medium material by using absolute ethyl alcohol and deionized water in sequence, and then drying the insulating medium material in a vacuum drying oven at the temperature of 50-60 ℃ for more than 24 hours;
the insulating medium material is a low-density polyethylene film and is prepared by a hot pressing method;
s2, immersing the insulating medium material in the dopamine solution to enable the surface of the insulating medium material to adsorb a layer of dopamine;
the concentration of the dopamine solution is 2g/L, and the soaking time at room temperature is 6-25 h;
s3, immersing the insulating material with dopamine adsorbed on the surface in a silver nitrate solution, reducing silver ions in the solution into nano silver particles under the action of the dopamine, and adsorbing the nano silver particles on the surface of the insulating material to form a dopamine-nano silver two-layer structure on the surface of the insulating material;
soaking the silver nitrate solution at the concentration of 50mmol/L for 0, 0.5, 1, 2 or 4 hours at room temperature;
and S4, immersing the insulating material with the two-layer structure in the dopamine solution again to obtain the insulating material with the dopamine-nano silver-dopamine sandwich structure on the surface.
The concentration of the dopamine solution is 2g/L, and the soaking time at room temperature is 6-25 h.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Table 1 shows the surface conductivity before and after the surface treatment of the low density polyethylene, and as the silver nitrate treatment time increases, the concentration of the surface nano silver ions increases, and the surface conductivity also increases. The data in the table show that the surface is covered with a dopamine-nano silver-dopamine sandwich structure, so that the surface conductivity of the insulating material can be increased by about two orders of magnitude.
TABLE 1 measurement of surface conductivity
And carrying out a surface potential attenuation experiment on the samples which are sequentially immersed in the dopamine solution, the silver nitrate solution and the dopamine solution, and calculating the surface trap distribution of the samples through a surface potential attenuation model. The surface potential of the low-density polyethylene film sample of which the surface is not covered with the dopamine-silver nitrate-dopamine sandwich structure is relatively slow in attenuation, and the central energy levels of a shallow trap and a deep trap are calculated to be 0.825eV and 0.880eV respectively, the central energy levels of the traps of the film sample immersed in the dopamine solution for 0.5h are calculated to be 0.83eV and 0.896eV respectively, and the central energy levels of the traps of the film sample immersed in the dopamine solution for 2h are calculated to be 0.845eV and 0.899eV respectively; the results show that by adopting the method, the surface trap level of the low-density polyethylene film sample with the dopamine-silver nitrate-dopamine sandwich structure on the surface is larger than that of the untreated sample, and the longer the sample is soaked in the silver nitrate solution, the larger the trap level is.
Referring to fig. 2, a dc vacuum surface flashover experiment was performed on the sample before and after the low density polyethylene surface was covered with the dopamine-nanosilver-dopamine sandwich structure. In the experimental process, a sample is placed on a finger-shaped electrode device, the finger-shaped electrode is composed of two finger-shaped stainless steel electrodes and a polytetrafluoroethylene substrate, and the end part of each electrode is semicircular. The sample is tightly pressed on the substrate by two finger electrodes, the electrode distance is 5mm, the electrode device is placed in a vacuum cavity, and the vacuum degree of the vacuum cavity is kept at 3 multiplied by 10 < -5 > Pa. And the voltage source for flashover test is a direct-current voltage source with the maximum voltage of 100 kV. And (4) testing the sample in a continuous boosting mode, wherein the voltage is boosted from 0 until the sample is subjected to flashover. And (3) using two samples for each sample, carrying out ten flashover tests on each sample, wherein the time interval between the two tests is 3min, recording the flashover voltage of each test, and taking the average value of the flashover voltages as the flashover voltage of the samples.
Table 2 shows the dc vacuum surface flashover voltage measurements before and after the low density polyethylene treatment.
As can be seen from table 2, covering the dopamine-nanosilver-dopamine sandwich structure on the surface of the low density polyethylene can improve the direct current vacuum surface flashover performance of the low density polyethylene, with the increase of the immersion time of the silver nitrate solution, the flashover voltage tends to increase first and then decrease, and when the immersion time of the sample in the silver nitrate solution is 2 hours, the sample with the dopamine-nanosilver-dopamine sandwich structure on the surface has the highest direct current surface flashover voltage, which is improved by 53% compared with the untreated low density polyethylene.
It can be seen that the method provided by the invention can significantly improve the direct current vacuum surface flashover voltage of the insulating dielectric material.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (4)
1. A method for improving vacuum surface flashover strength of an insulating material is characterized in that the insulating medium material which is cleaned and dried is sequentially soaked in a dopamine solution, a silver nitrate solution and a dopamine solution at room temperature to prepare the insulating material with a dopamine-nano silver-dopamine sandwich structure on the surface, and the method comprises the following steps:
s1, ultrasonically cleaning the insulating medium material by using absolute ethyl alcohol and deionized water in sequence, and then drying the insulating medium material in a vacuum drying oven at the drying temperature of 50-60 ℃ for more than 24 hours;
s2, immersing the insulating medium material in the dopamine solution to enable the surface of the insulating medium material to adsorb a layer of dopamine;
s3, immersing the insulating material with dopamine adsorbed on the surface in a silver nitrate solution with the concentration of 50mmol/L for 0-4 h, reducing silver ions in the solution into nano silver particles under the action of the dopamine, and adsorbing the nano silver particles on the surface of the insulating material to form a dopamine-nano silver two-layer structure on the surface of the insulating material;
and S4, immersing the insulating material with the two-layer structure in the dopamine solution again to obtain the insulating material with the dopamine-nano silver-dopamine sandwich structure on the surface.
2. The method for improving the flashover strength of the vacuum surface of the insulation material as claimed in claim 1, wherein in the step S2, the concentration of the dopamine solution is 2g/L, and the soaking time at room temperature is 6-25 h.
3. The method for improving the flashover strength of the vacuum surface of the insulation material as claimed in claim 1, wherein in the step S4, the concentration of the dopamine solution is 2g/L, and the soaking time at room temperature is 6-25 h.
4. The method for improving the vacuum surface flashover strength of the insulating material as claimed in claim 1, 2 or 3, wherein the insulating medium material is a low density polyethylene film and is prepared by a hot pressing method.
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