CN117116576B - Method and device for preparing high-conductivity nonlinear coefficient coating induced by in-situ electric field - Google Patents

Method and device for preparing high-conductivity nonlinear coefficient coating induced by in-situ electric field Download PDF

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Publication number
CN117116576B
CN117116576B CN202310669153.4A CN202310669153A CN117116576B CN 117116576 B CN117116576 B CN 117116576B CN 202310669153 A CN202310669153 A CN 202310669153A CN 117116576 B CN117116576 B CN 117116576B
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coating
insulating
electric field
curing
conductivity
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CN117116576A (en
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潘成
毛诗壹
唐炬
潘子君
郝留成
袁端鹏
王亚祥
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Wuhan University WHU
Pinggao Group Co Ltd
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Wuhan University WHU
Pinggao Group Co Ltd
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    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D163/00Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B05SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05DPROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/02Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
    • B05D3/0209Multistage baking
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B05SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05DPROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/02Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
    • B05D3/0254After-treatment
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B05SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05DPROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/14Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by electrical means
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B05SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05DPROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D5/00Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
    • B05D5/12Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain a coating with specific electrical properties
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B05SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05DPROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/24Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials for applying particular liquids or other fluent materials
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40Additives
    • C09D7/60Additives non-macromolecular
    • C09D7/61Additives non-macromolecular inorganic
    • C09D7/62Additives non-macromolecular inorganic modified by treatment with other compounds
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B17/00Insulators or insulating bodies characterised by their form
    • H01B17/56Insulating bodies
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B19/00Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
    • H01B19/04Treating the surfaces, e.g. applying coatings
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B05SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05DPROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2504/00Epoxy polymers
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00Technologies relating to chemical industry
    • Y02P20/10Process efficiency

Abstract

The invention discloses a preparation method and a device of an in-situ electric field induced high-conductivity nonlinear coefficient coating, wherein the preparation method comprises the steps of mixing epoxy resin, a curing agent, an accelerator, a silane coupling agent and a functional filler to obtain a composite insulating coating; coating the composite insulating paint on the surface of an insulating substrate, and carrying out first curing on the composite insulating paint on the surface of the insulating substrate under the action of an alternating current electric field; and removing the alternating current electric field, and performing secondary curing on the composite insulating coating on the surface of the insulating substrate to form a high-conductivity nonlinear coefficient coating on the surface of the insulating substrate. The preparation method of the coating provided by the invention can ensure that the insulating coating with low filler concentration has higher nonlinear conductivity, effectively and uniformly electric field on the insulating surface, and can regulate and control charge aggregation and dispersion, thereby improving the creepage resistance of the insulating material.

Description

Method and device for preparing high-conductivity nonlinear coefficient coating induced by in-situ electric field
Technical Field
The invention relates to the technical field of insulating coating preparation, in particular to a method and a device for preparing a high-conductivity nonlinear coefficient coating induced by an in-situ electric field.
Background
With the rapid development of ultra-high voltage direct current transmission technology, gas insulated metal enclosed switchgear (GIS) has been widely focused on due to its small floor space, high operational reliability and other outstanding advantages. However, under the action of long-term unipolar direct current electric field, charged particles can move in the same direction in a directional manner and continuously accumulate at a gas-solid insulation interface, so that the local electric field distribution of the insulation surface is distorted, the surface flashover accident is easily caused, and the insulation grade of equipment is severely limited. The improvement of the electrical strength of the insulator along the surface can help to promote the research, development and application of high-voltage direct-current electrical insulation equipment.
The surface coating of insulating materials is considered as a potential method for electric charge and electric field control for industrial application, and in particular, the coating of nonlinear conductive functional materials typified by silicon carbide/epoxy and the like has been attracting attention in recent years. The non-linear conductivity characteristic is helpful for uniform electric field distribution on the surface of the insulator and accelerating charge along-surface dissipation, so that surface charge accumulation is inhibited, and the insulator along-surface tolerance characteristic is improved. However, the doping concentration of the functional filler in the polymer matrix affects the practical application effect of the nonlinear conductive coating, and the silicon carbide doped epoxy composite material is taken as an example: under lower doping concentration, the composite material is difficult to show stable nonlinear conductivity, and the higher doping concentration can bring about the problems of difficult uniform dispersion in the preparation process of the coating, reduced long-term binding force between the coating and the insulating substrate, insufficient mechanical strength of a finished product sample and the like.
Disclosure of Invention
In order to solve the problems in the prior art, an in-situ alternating current electric field is externally applied in the curing process of the composite insulating coating, so that the functional fillers are orderly arranged into chains along the direction of the electric field until the curing is completed. Under the same doping concentration, compared with a composite insulating coating with randomly distributed fillers, the coating with the particle ordered arrangement structure can show better nonlinear conductivity along the electric field direction, more effectively and uniformly distribute the electric field of the gas-solid interface under the direct current condition, and inhibit charge accumulation. The nonlinear conductivity of the cured composite coating can be regulated and controlled by regulating and controlling the frequency, amplitude, pressing time and other parameters of the in-situ electric field, so that the electric field and charge regulating effect of the nonlinear conductivity functional coating is improved, and the gas-solid insulation direct current edge tolerance performance of the coating is further improved.
In order to achieve the above object, the present invention provides a method for preparing an in-situ electric field induced high conductivity nonlinear coefficient coating, comprising,
coating the composite insulating paint on the surface of an insulating substrate, and carrying out first curing on the composite insulating paint on the surface of the insulating substrate under the action of an alternating current electric field;
and removing the alternating current electric field, and performing secondary curing on the composite insulating coating on the surface of the insulating substrate to form a high-conductivity nonlinear coefficient coating on the surface of the insulating substrate.
Further, the composite insulating coating is obtained by mixing epoxy resin, a curing agent, an accelerator, a silane coupling agent and functional filler.
Further, the preparation of the composite insulating paint specifically comprises,
the mass ratio is 80-120: 70-90: 0.5 to 1:0.4 to 17: 8-340, obtaining epoxy resin, a curing agent, an accelerator, a silane coupling agent and functional filler;
dispersing the silane coupling agent in absolute ethyl alcohol, then adding epoxy resin and functional filler, uniformly mixing, and volatilizing the absolute ethyl alcohol to obtain mixed liquid;
and adding a curing agent and an accelerator into the mixed liquid, uniformly mixing, and then degassing to obtain the composite insulating coating.
Further, the epoxy resin is E51; the curing agent is methyl hexahydrophthalic anhydride; the accelerator is phenol; the silane coupling agent is KH550; the functional filler is one or more of silicon carbide, zinc oxide, carbon black, graphene oxide, carbon fiber, carbon nano tube and graphite with the thickness of 0.1-100 mu m.
Further, the first curing is a two-stage curing,
the first stage is to keep the temperature between 80 and 100 ℃ for 1 to 3 hours;
the second stage is to keep the temperature at 100-120 ℃ for 0.2-1 h.
Further, the second curing is carried out at 100-120 ℃ for 9-10 hours.
Further, the intensity of the alternating current electric field is 50-1000V/mm, and the alternating current frequency is determined by CM factors of the functional filler and the insulating base material.
The invention also provides a high-conductivity nonlinear coefficient coating which is prepared by adopting the method.
The invention also provides a device for realizing the method, which comprises a first clamping plate, an insulating isolation plate, an insulating base material, a reaction plate, a second clamping plate, an electrode and a fixing piece;
the reaction plate comprises a liquid injection port, an exhaust port, a coating groove and an electrode reserved groove, wherein the liquid injection port and the exhaust port are both arranged on one side of the reaction plate, the electrode reserved groove is arranged on the other side of the reaction plate, the coating groove is arranged above the reaction plate, and the coating groove is communicated with the electrode reserved groove, the liquid injection port and the exhaust port;
the cross-sectional area of the insulating substrate is larger than the bottom area of the coating groove;
the first clamping plate, the insulating isolation plate, the reaction plate and the second clamping plate are provided with communicated threaded holes, the fixing piece is provided with threads matched with the threaded holes, the fixing piece is matched with the threads to enable the first clamping plate, the insulating isolation plate, the insulating base material, the reaction plate and the second clamping plate to be combined from top to bottom, then composite insulating paint is poured into the liquid injection port and then transferred to the oven for heating, and an electrode is used for providing an alternating current electric field in the paint groove.
Further, the depth of the electrode pre-groove is smaller than the depth of the coating groove;
the reaction plate further includes a built-in heater.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention utilizes the in-situ alternating current electric field to drive functional filler particles to be arranged into chains in the epoxy resin matrix along the electric field direction, thereby obtaining the insulating coating with higher nonlinear conductivity under the same doping concentration. The technical difficulty and performance reduction caused by doping of the high-concentration filler are avoided. In addition, lower doping concentrations also mean less raw material, making the process for coating preparation more economical.
(2) The method for externally applying the in-situ alternating current electric field to the liquid coating in the curing process has the advantages of lower requirement on doped particles, more flexible regulation and control of the electric field, wide applicability, lower cost and good application prospect.
(3) The curing mould adopted in the invention needs to meet the requirements of high-temperature curing, externally applied alternating current electric field and sealing liquid paint. Therefore, the selected insulating material has higher mechanical strength, is not easy to deform and good in heat conductivity, has low roughness and is easy to process, the requirement of being used as a high-temperature curing mold is met, and the insulating material can be assembled with an electrode to construct a proper electric field. The clamping plate type die designed by taking the material as a carrier can also meet the sealing requirement of liquid pouring.
(4) The shape and the size of the composite coating provided by the invention are determined by the reserved grooves in the clamping plate type die, different insulating coatings can be poured by changing the shape and the size of the grooves, and the form is flexible.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram showing the structure of an in-situ electric field induced high conductivity nonlinear coefficient coating preparation apparatus in example 1 of the present invention;
FIG. 2 is a flow chart showing the method of preparing the in-situ electric field induced high conductivity nonlinear coefficient coating in example 2 of the present invention;
FIG. 3 shows the CM factor versus AC frequency for a silicon carbide/epoxy composite;
FIG. 4 is a graph showing the linking behavior of silicon carbide particles under the action of in-situ AC electric field in example 2 of the present invention;
FIG. 5 is a photograph showing an in-situ electric field induced high conductivity nonlinear coefficient coating prepared in accordance with example 2 of the present invention;
FIG. 6 shows the electrical conductivity characteristics of the coatings obtained in example 2 and comparative examples of the present invention;
in the figure:
1. a first clamping plate; 2. an insulating spacer; 3. an insulating substrate; 4. a reaction plate; 41. a paint groove; 42. a liquid injection port; 43. an exhaust port; 44. an electrode reserving groove; 5. a second clamping plate; 6. and (3) a threaded hole.
Detailed Description
The endpoints of the ranges and any values disclosed in the present invention are not limited to the precise range or value, and the range or value should be understood to include values close to the range or value. For numerical ranges, one or more new numerical ranges may be obtained in combination with each other between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point values, and are to be considered as specifically disclosed in the present invention.
The following description of specific embodiments of the present invention and the accompanying drawings will provide a clear and complete description of the technical solutions of embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
As shown in fig. 1, the in-situ electric field induced high conductivity nonlinear coefficient coating preparation device comprises a first clamping plate 1, an insulating isolation plate 2, an insulating base material 3, a reaction plate 4, a second clamping plate 5, an electrode and a fixing piece;
the reaction plate 4 comprises a liquid injection port 42, an air exhaust port 43, a coating groove 41 and an electrode reserved groove 44, wherein the liquid injection port 42 and the air exhaust port 43 are both arranged on one side of the reaction plate 4, the electrode reserved groove 44 is arranged on the other side of the reaction plate 4, the coating groove 41 is arranged above the reaction plate 4, and the coating groove 41 is communicated with the electrode reserved groove 44, the liquid injection port 42 and the air exhaust port 43.
The insulating substrate has a cross-sectional area greater than the floor area of the paint recess.
The first clamping plate 1, the insulating isolation plate 2, the reaction plate 4 and the second clamping plate 5 are provided with communicated threaded holes 6, and the fixing piece is provided with threads matched with the threaded holes 6. The fixing piece is in threaded fit with the threaded hole 6, so that when the first clamping plate 1, the insulating isolation plate 2, the insulating base material 3, the reaction plate 4 and the second clamping plate 5 are combined from top to bottom, the central lines of the first clamping plate 1, the insulating isolation plate 2, the insulating base material 3, the reaction plate 4 and the second clamping plate 5 are aligned. Pouring the composite insulating paint from the liquid injection port after combination, transferring to an oven for heating, and providing an alternating current electric field in the paint groove by using an electrode, so that the composite insulating paint on the insulating substrate 3 is cured for the first time under the action of the alternating current electric field; the alternating electric field is then removed and a second cure is performed to form a high conductivity nonlinear coefficient coating on the surface of the insulating substrate.
Preferably, the fixing member is a screw;
preferably, the first clamping plate 1 and the second clamping plate 5 are made of the same material and are made of stainless steel.
Preferably, the insulating spacer 2 and the reaction plate 4 are made of the same material and are both hard insulating materials.
Preferably, the insulating substrate 3 is obtained by curing and demolding in a metal recess mold in which the insulating thermosetting material is poured. The curing conditions are as follows: the temperature was kept at 90℃for 2 hours and then at 110℃for 10 hours. The length, width and height of the obtained insulating substrate 3 were 30mm×30mm×3mm, respectively.
Preferably, the length, width and height of the paint groove 41 are 20mm×20mm×0.2mm, respectively; the thickness of the electrode is 0.1mm, and the distance between the two electrodes is 20mm; thus, the thickness of the high conductivity nonlinear coefficient coating layer obtained was 0.3mm.
Preferably, the reaction plate further comprises an internal heater that provides a curing temperature for the composite insulating coating in the coating recess, thereby eliminating the need to transfer the device to an oven for heating.
Example 2
As shown in fig. 2, a method for preparing an in-situ electric field induced high conductivity nonlinear coefficient coating, using the apparatus of example 1, comprises the steps of:
step 1, preparation of paint and insulating base material 3
1.1 preparing epoxy silicon carbide polymer insulating paint
(1) Weighing 20g of epoxy resin, 16g of methyl hexahydrophthalic anhydride, 0.1g of phenol, 4.03g of silicon carbide with the particle size of 5 mu m and 0.2g of silane coupling agent, and placing the epoxy resin and the silicon carbide in a 75 ℃ oven for drying for later use;
(2) Dissolving a silane coupling agent in 100g of absolute ethyl alcohol, adding silicon carbide particles after ultrasonic dispersion in a water bath at 60-65 ℃, continuing ultrasonic treatment for 30min, simultaneously carrying out mechanical stirring at 400r/min, then adding epoxy resin, and stirring and fully mixing under an oil bath at 65 ℃ to ensure that the epoxy resin and the silicon carbide particles are uniformly mixed and fully volatilize the ethyl alcohol in the mixed liquid to obtain a mixed liquid a;
(3) Adding methyl hexahydrophthalic anhydride and phenol into the mixed liquid a obtained in the step (2), continuously stirring at 65 ℃ in an oil bath, and uniformly dispersing to obtain mixed liquid b;
(4) And (3) transferring the mixed liquid b obtained in the step (3) to a vacuum oven at 65 ℃ for degassing, and simultaneously, mechanically stirring to sufficiently remove the gas in the mixed liquid b to obtain the epoxy silicon carbide polymer insulating coating, wherein the mass ratio of silicon carbide is 4.03/40.3=10%, so that the mass ratio of silicon carbide is 10% in the embodiment.
1.2 preparation of insulating substrate 3
(1) According to the mass ratio of 100:80:0.5, weighing and mixing epoxy resin, a curing agent and an accelerator, stirring and mixing uniformly in an oil bath at 65 ℃, and then carrying out vacuum degassing to obtain an epoxy-based liquid material;
(2) Pouring the epoxy-based liquid material obtained in the step (1) into a metal groove die, wherein the length, width and height of the metal groove die are 30mm multiplied by 3mm; then preserving heat at 90 ℃ for 2 hours, and then preserving heat at 110 ℃ for 10 hours for curing;
(3) Demolding to obtain the insulating substrate 3.
Step 2, assembling in-situ electric field induced high-conductivity nonlinear coefficient coating preparation device
(1) The insulating base material 3 is cleaned and dried, two conductive adhesive tapes are stuck in an electrode reserving groove 44 on the reaction plate 4 to serve as electrodes, the thickness of the electrodes is 0.1mm, and the interval is 20mm;
(2) The first clamping plate 1, the insulating isolation plate 2, the insulating base material 3, the reaction plate 4 and the second clamping plate 5 are fixed by using screws after being aligned with the central lines, and meanwhile, the electrodes extend out of the electrode reservation grooves 44 and are connected with an alternating current power supply.
Step 3, solidifying by an alternating current electric field;
the epoxy-based silicon carbide polymer insulating paint is injected into the paint groove 41 from the liquid injection end, the alternating current voltage with the voltage amplitude of 20kV is used, the power frequency is selected, referring to fig. 3, 1kHz is selected as the power frequency in consideration of the dielectric loss of the material, the mold is placed in an oven under the action of an alternating current electric field, the temperature is raised to 90 ℃ for 2 hours, and then the temperature is raised to 110 ℃ for 0.5 hour.
Step 4, high temperature curing
And the alternating current power supply is turned off, as shown in the figure 4, at the moment, the silicon carbide particles in the epoxy silicon carbide polymer insulating coating are aligned and linked, the particle chains are not dispersed after the pressure is removed, and the heat preservation is continued for 9.5 hours at the temperature of 110 ℃ to finish the solidification.
Step 5, demolding
And removing the screw, separating the insulating base material 3 from the reaction plate 4, and removing the electrode, as shown in fig. 5, to obtain the insulating base material 3 with the in-situ electric field induced high-conductivity nonlinear coefficient coating. It can be seen that the coating has a smooth surface and is uniformly applied.
Examples 3 to 5
Substantially the same as in example 2, the only difference is that: the alternating current voltages with voltage amplitudes of 1kV, 5kV and 10kV are used in the solidification of the alternating current electric field in the step 3;
the results show that these coatings are smooth and uniformly applied, and have no obvious difference in appearance from the coating prepared in example 2.
Comparative example
Substantially the same as in example 2, the only difference is that: the ac power supply is always in an off state.
The electrical conductivity properties of the coatings obtained in example 2 and comparative example were tested, and as shown in fig. 6, it can be seen that the resulting coatings after in-situ electric field induction applied exhibited significant nonlinear electrical conductivity properties under changes in the electric field.
In summary, in the high-temperature curing process of the composite insulating coating, an alternating electric field is externally applied to promote the filler particles to be arranged into chains along the direction of the electric field. The obtained composite coating has good nonlinear conductivity characteristic at lower doping concentration, can effectively regulate and control the surface charge aggregation and dispersion characteristic of the insulating material and uniform electric field distribution, and can avoid the problems of difficult uniform dispersion of the filler, reduced long-term binding force between the coating and a substrate, insufficient mechanical strength of a finished product sample and the like caused by high doping concentration. The method adopted by the invention takes the alternating current electric field as a control field of filler particles, is easier to regulate and control, has wide applicability and lower cost, and has good application prospect.
Finally, it should be noted that: the foregoing description is only illustrative of the preferred embodiments of the present invention, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements or changes may be made without departing from the spirit and principles of the present invention.

Claims (5)

1. The preparation method of the in-situ electric field induced high-conductivity nonlinear coefficient coating is characterized by comprising the following steps of,
coating the composite insulating paint on the surface of an insulating substrate, and carrying out first curing on the composite insulating paint on the surface of the insulating substrate under the action of an alternating current electric field;
removing the alternating current electric field, and performing secondary curing on the composite insulating coating on the surface of the insulating substrate to form a high-conductivity nonlinear coefficient coating on the surface of the insulating substrate;
the composite insulating coating is prepared by mixing epoxy resin, a curing agent, an accelerator, a silane coupling agent and functional filler;
the preparation of the composite insulating paint specifically comprises the steps of,
the mass ratio of the components is 80-120: 70-90: 0.5-1: 0.4-17: 8-340, obtaining epoxy resin, a curing agent, an accelerator, a silane coupling agent and functional filler;
dispersing the silane coupling agent in absolute ethyl alcohol, then adding epoxy resin and functional filler, uniformly mixing, and volatilizing the absolute ethyl alcohol to obtain mixed liquid;
adding a curing agent and an accelerator into the mixed liquid, uniformly mixing, and then degassing to obtain a composite insulating coating;
the first curing is a two-stage curing,
the first stage is to keep the temperature at 80-100 ℃ for 1-3 hours;
the second stage is to keep the temperature at 100-120 ℃ for 0.2-1 h;
the second curing is carried out at 100-120 ℃ for 9-10 hours;
the intensity of the alternating current electric field is 50-1000V/mm, and the alternating current frequency is determined by CM factors of the functional filler and the insulating base material.
2. The method of claim 1, wherein the epoxy resin is E51; the curing agent is methyl hexahydrophthalic anhydride; the accelerator is phenol; the silane coupling agent is KH550; the functional filler is one or more of silicon carbide, zinc oxide, carbon black, graphene oxide, carbon fiber, carbon nano tube and graphite with the thickness of 0.1-100 mu m.
3. A high conductivity nonlinear coefficient coating prepared by the method of claim 1 or 2.
4. An apparatus for carrying out the method of claim 1 or 2, comprising a first clamping plate, an insulating spacer plate, an insulating substrate, a reaction plate, a second clamping plate, an electrode, and a fixture;
the reaction plate comprises a liquid injection port, an exhaust port, a coating groove and an electrode reserved groove, wherein the liquid injection port and the exhaust port are both arranged on one side of the reaction plate, the electrode reserved groove is arranged on the other side of the reaction plate, the coating groove is arranged above the reaction plate, and the coating groove is communicated with the electrode reserved groove, the liquid injection port and the exhaust port;
the cross-sectional area of the insulating substrate is larger than the bottom area of the coating groove;
the first clamping plate, the insulating isolation plate, the reaction plate and the second clamping plate are provided with communicated threaded holes, the fixing piece is provided with threads matched with the threaded holes, the fixing piece is matched with the threads to enable the first clamping plate, the insulating isolation plate, the insulating base material, the reaction plate and the second clamping plate to be combined from top to bottom, then composite insulating paint is poured into the liquid injection port and then transferred to the oven for heating, and an electrode is used for providing an alternating current electric field in the paint groove.
5. The apparatus of claim 4, wherein the electrode pregroove has a depth less than a depth of the paint groove;
the reaction plate further includes a built-in heater.
CN202310669153.4A 2023-06-06 2023-06-06 Method and device for preparing high-conductivity nonlinear coefficient coating induced by in-situ electric field Active CN117116576B (en)

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US3450655A (en) * 1965-04-09 1969-06-17 Ransburg Electro Coating Corp Non-aqueous suspension for electrophoretically coating articles comprising a pigment and an organic-solventsoluble thermosetting resin
CN109830347A (en) * 2019-01-29 2019-05-31 天津大学 The high voltage direct current GIL quick industrial processing method of surface function gradient insulator
CN110070968A (en) * 2019-03-20 2019-07-30 天津大学 A kind of sub- preparation method of nonlinear conductance coating insulation of resistance to direct current flashover
CN112063262A (en) * 2020-06-18 2020-12-11 武汉大学 Epoxy nonlinear conductive coating and preparation process thereof
CN113871113A (en) * 2021-09-18 2021-12-31 天津大学 Method for forming coating nonlinear conductive basin-type insulator
BR112022022592A2 (en) * 2020-06-17 2022-12-27 Nippon Steel Corp COATING COMPOSITION FOR AN ELECTRIC STEEL SHEET, ELECTRIC STEEL SHEET COATED ON THE SURFACE FOR ADHESION, AND, LAMINATED CORE

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1457292A (en) * 1964-04-30 1966-11-04 Ford France New coating material and process for its electrical deposition
US3450655A (en) * 1965-04-09 1969-06-17 Ransburg Electro Coating Corp Non-aqueous suspension for electrophoretically coating articles comprising a pigment and an organic-solventsoluble thermosetting resin
CN109830347A (en) * 2019-01-29 2019-05-31 天津大学 The high voltage direct current GIL quick industrial processing method of surface function gradient insulator
CN110070968A (en) * 2019-03-20 2019-07-30 天津大学 A kind of sub- preparation method of nonlinear conductance coating insulation of resistance to direct current flashover
BR112022022592A2 (en) * 2020-06-17 2022-12-27 Nippon Steel Corp COATING COMPOSITION FOR AN ELECTRIC STEEL SHEET, ELECTRIC STEEL SHEET COATED ON THE SURFACE FOR ADHESION, AND, LAMINATED CORE
CN112063262A (en) * 2020-06-18 2020-12-11 武汉大学 Epoxy nonlinear conductive coating and preparation process thereof
CN113871113A (en) * 2021-09-18 2021-12-31 天津大学 Method for forming coating nonlinear conductive basin-type insulator

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