CN113593792B

CN113593792B - Vacuum insulator with gel layer and preparation method thereof

Info

Publication number: CN113593792B
Application number: CN202110808784.0A
Authority: CN
Inventors: 刘文元; 霍艳坤; 柯昌凤; 陈昌华; 孙钧; 程军
Original assignee: Northwest Institute of Nuclear Technology
Current assignee: Northwest Institute of Nuclear Technology
Priority date: 2021-07-16
Filing date: 2021-07-16
Publication date: 2023-02-28
Anticipated expiration: 2041-07-16
Also published as: CN113593792A

Abstract

The invention discloses a vacuum insulator with a gel layer and a preparation method thereof. The insulator consists of a solid insulator matrix and a liquid gel layer coated on the surface of the matrix, wherein the prepared gel layer can stably exist on the surface of the insulator, can keep stable in a static state and has certain fluidity under the drive of power. The preparation of the gel layer can greatly improve the flashover voltage of the vacuum surface of the insulator.

Description

Vacuum insulator with gel layer and preparation method thereof

Technical Field

The invention belongs to the technical field of vacuum high-voltage insulation, and relates to a vacuum insulator with a gel layer and a preparation method thereof.

Background

Insulator vacuum surface flashover is a bottleneck problem in the field of vacuum insulation, and the voltage applied when flashover occurs is far lower than the breakdown voltage of an insulator body and the breakdown voltage of a vacuum gap with the same length. The existence of the phenomenon greatly reduces the compressive strength of the whole insulation system and limits the use voltage and the output power of most pulse power systems, so that the development of a vacuum insulator with high compressive level is very important for improving the output power and the operation stability of the pulse power system.

Vacuum surface flashover is a breakdown discharge phenomenon occurring along the solid insulator and vacuum interface, and is also a discharge phenomenon occurring at the solid-vacuum interface. In order to improve the flashover voltage of the vacuum edge surface of the insulator, researchers in the field conduct a large amount of research, and various methods for improving the flashover voltage of the vacuum edge surface of the insulator are provided, so that the flashover voltage of the insulator is improved to a certain extent.

However, in the research center in this field, the whole history of vacuum insulation research always focuses on how to improve the structure or material of the insulator itself to realize flashover withstand voltage, but the effect is not ideal all the time.

Disclosure of Invention

In order to solve the problem that the flashover and voltage-resistant effects are not ideal by improving the structure and the material of the insulator, the invention provides a method for converting the discharge of a solid-vacuum interface into the discharge of a liquid-vacuum interface by preparing a gel layer on the surface of the insulator. The solid-vacuum interface with poor pressure resistance is converted into a liquid-vacuum interface with strong pressure resistance, so that the flashover voltage of the insulator along the surface is effectively improved.

The specific technical scheme of the invention is as follows:

the vacuum insulator with the gel layer comprises a solid insulator substrate and a liquid gel layer arranged on the surface of the solid insulator substrate; a solid-liquid interface is formed between the liquid gel layer and the solid insulator matrix; a liquid and vacuum interface is formed between the liquid gel layer and the external vacuum.

Further, the gel layer comprises insulating oil, nano silicon dioxide, dimethyl dichlorosilane and water.

Further, the weight ratio of the insulating oil, the nano-silica, the dimethyldichlorosilane and the water in the gel layer is 100:6 to 12:0.5 to 1:0.5 to 1.

Further, the weight ratio of the insulating oil, the nano-silica, the dimethyldichlorosilane and the water in the gel layer is 100:8:0.5:0.5.

further, the preparation process of the gel layer comprises the following steps: insulating oil, nano silicon dioxide, dimethyl dichlorosilane and water are mixed according to the weight ratio of 100:6 to 12:0.5 to 1:0.5 to 1; then ultrasonic dispersion is carried out by stirring, reaction is carried out for 30 minutes, and the dimethyldichlorosilane is fully hydrolyzed and coupled with the nano silicon dioxide to form a mixed solution; and finally, putting the prepared mixed solution into a vacuum oven, vacuumizing at 50 ℃, and keeping for 8 hours to remove excessive water in the mixed solution, thereby forming gel.

Furthermore, the solid insulator substrate is made of organic glass, crosslinked polystyrene, epoxy resin, nylon, polyimide, ceramic or quartz.

Furthermore, the thickness of the liquid gel layer is 1-10 mm.

Meanwhile, the invention also provides a preparation method of the vacuum insulator with the gel layer, which comprises the following steps:

step 1: preparation of the gel

Step 1.1: insulating oil, nano silicon dioxide, dimethyl dichlorosilane and water are mixed according to the weight ratio of 100:6 to 12:0.5 to 1:0.5 to 1;

step 1.2: ultrasonic dispersion is carried out by stirring, reaction is carried out for 30 minutes, and the dimethyldichlorosilane is fully hydrolyzed and then coupled with the nano silicon dioxide to form a mixed solution;

step 1.3: putting the prepared mixed solution into a vacuum oven, vacuumizing at 50 ℃, and keeping for 8 hours to remove excessive water in the mixed solution, thereby forming gel;

step 2: preparing a required insulator matrix by a mechanical processing mode according to the geometric structure and the size of the required insulator;

and step 3: coating the gel prepared in the step 1 on the surface of an insulator substrate, and completely coating the whole insulator;

and 4, step 4: and putting the insulator matrix coated with the gel into a vacuum container for vacuumizing treatment, and exhausting gas in the gel, thereby completing the preparation of the insulator.

Further, in the method, the insulator matrix is made of organic glass, crosslinked polystyrene, epoxy resin, nylon, polyimide, ceramic or quartz.

Further, in the method, the thickness of the gel layer is 1-10 mm.

The technical scheme of the invention has the following beneficial effects:

1. the insulator with the gel layer provided by the invention has the advantages that the single solid-vacuum interface of the original vacuum insulator is converted into the combination of the solid-liquid interface and the liquid-vacuum interface by constructing the gel layer, because the withstand voltage strength of the solid-liquid interface is far higher than that of the solid-vacuum interface, flashover cannot occur on the newly formed solid-liquid interface, and meanwhile, the newly formed liquid-vacuum interface has low gas adsorption capacity relative to the surface of the solid-vacuum interface, and is not easy to release gas under electronic stimulation to form an atmosphere environment required by breakdown; and because the liquid gel layer has certain fluidity, the surface charges are difficult to accumulate (if the charges accumulate, the charges are separated because the repulsive force of the same charges drives the liquid to flow), so that the electric field distortion caused by the charges accumulate on the surface can not occur; further, when electrons are bombarded onto the liquid gel layer, the incidence depth is large, and the generated secondary electrons are difficult to be emitted to the surface of the insulator. Therefore, the gel layer can inhibit a plurality of processes of flashover development, and the flashover voltage of the insulator is greatly improved.

2. The invention is suitable for insulators made of various insulating materials, such as organic glass, crosslinked polystyrene, epoxy resin, nylon, polyimide, ceramic, quartz and the like, which can be applied to the field of vacuum insulation.

3. The liquid gel layer prepared by adopting the insulating oil, the nano silicon dioxide, the dimethyldichlorosilane and the water has strong stability and long service life, and when the surface is in flashover, the generated ablation residues can be dissolved by the gel layer, so that the surface structure is kept unchanged, and the pressure resistance is further kept stable.

4. The liquid gel layer has certain fault-tolerant capability and self-repairing capability, when the surface gel is not uniform due to uneven coating or external force, the liquid gel can be driven to flow by the heat effect or charge repulsion generated in the discharging process, and the liquid gel is uniformly paved on the surface of the whole insulator, so that stable flashover voltage resistance is obtained.

5. Compared with the liquid insulating oil, the gel layer prepared from the insulating oil, the nano silicon dioxide, the dimethyldichlorosilane and the water not only keeps the high insulativity of the liquid insulating oil, but also avoids the defects that the liquid insulating oil is easy to flow and cannot stably exist on the surface of an insulating material in a certain thickness.

Drawings

FIG. 1 is a schematic view of a gel layer insulator structure;

fig. 2 is a flow chart of gel layer insulator preparation.

Detailed Description

The invention provides a vacuum insulator with a gel layer, wherein the gel layer 2 is prepared on the surface of an insulator substrate 1, and the gel layer 2 has better stability in a static state and certain fluidity under the action of a driving force. Through the preparation of the gel layer 2, the solid-vacuum interface of the insulator can be converted into the combination of a solid-liquid interface (interface A in figure 1) and a liquid-vacuum interface (interface B in figure 1), and the characteristic that the compressive strength of two newly formed interfaces is higher than that of the solid-vacuum interface is utilized, so that the flashover voltage of the insulator is greatly improved.

To further demonstrate the performance of the insulator of the present invention, the following is a more detailed description of the insulator of the present invention through the preparation of three different sets of insulators and a comparison of the performance with existing insulators.

Example 1

Referring to fig. 2:

1. 99 alumina ceramics is selected as the insulator base material and is processed into a columnar insulator base with the thickness of 10mm and the diameter of 30mm by a mechanical processing mode.

2. Insulating oil, nano silicon dioxide, dimethyl dichlorosilane and water are mixed according to the weight ratio of 100:8:0.7:0.7, uniformly mixing, reacting for 30 minutes to fully hydrolyze the dimethyldichlorosilane and couple with the nano silicon dioxide to form a mixed solution, finally placing the mixed solution into a vacuum oven, vacuumizing at 50 ℃ and keeping for 8 hours to remove excessive water in the mixed solution, and preparing into gel.

3. The insulator is subjected to overall gel coating by using the prepared gel, the coating thickness of the gel layer is 1 mm, then the coated insulator is placed in a vacuum container for vacuum pumping treatment, and gas in the gel is discharged to prepare an insulator sample with the gel layer which is marked as a columnar insulator A.

Example 2

Referring to fig. 2:

1. quartz is selected as the insulator base material, and is processed into a cylindrical insulator base with the thickness of 5mm and the diameter of 30mm by a mechanical processing mode.

2. Insulating oil, nano silicon dioxide, dimethyl dichlorosilane and water are mixed according to the weight ratio of 100:6:0.5:0.5, uniformly mixing, reacting for 30 minutes to fully hydrolyze the dimethyldichlorosilane and couple with the nano-silica to form a mixed solution, finally putting the mixed solution into a vacuum oven, vacuumizing at 50 ℃ and keeping for 8 hours to remove excessive water in the mixed solution, and preparing into gel.

3. And performing overall gel coating on the insulator by using the prepared gel, wherein the coating thickness of the gel layer is 5mm, then putting the coated insulator into a vacuum container for vacuumizing treatment, and exhausting gas in the gel to prepare an insulator sample with the gel layer, which is marked as a columnar insulator B.

Example 3

Referring to fig. 2:

1. organic glass (PMMA) is selected as an insulator matrix material, and a cylindrical insulator matrix with the thickness of 5mm and the diameter of 30mm is processed by utilizing a machining mode.

2. Insulating oil, nano silicon dioxide, dimethyl dichlorosilane and water are mixed according to the weight ratio of 100:12:1:1, reacting for 30 minutes to fully hydrolyze the dimethyldichlorosilane and couple the dimethyldichlorosilane with the nano silicon dioxide to form a mixed solution, finally placing the mixed solution into a vacuum oven, vacuumizing at 50 ℃ and keeping for 8 hours to remove excessive water in the mixed solution, and preparing the gel.

3. And performing overall gel coating on the insulator by using the prepared gel, wherein the coating thickness of the gel layer is 10mm, then putting the coated insulator into a vacuum container for vacuumizing treatment, and exhausting gas in the gel to prepare an insulator sample with the gel layer, which is marked as a columnar insulator C.

The columnar insulator A, B, C prepared in the above examples 1 to 3 and the columnar insulator D machined with the same insulating material were subjected to a vacuum flashover voltage test on a vacuum pulse surface flashover test bench with a pulse width of 500 ns. The flashover voltage test results are shown in table 1, and it can be seen that the flashover voltage of the cylindrical insulator A, B, C prepared in examples 1 to 3 is improved by 60 to 120% compared with that of the cylindrical insulator D, which indicates that the flashover voltage of the insulator can be greatly improved by the gel layer insulator structure.

TABLE 1

Claims

1. A vacuum insulator with a gel layer is characterized by comprising a solid insulator substrate and a liquid gel layer arranged on the surface of the solid insulator substrate; a solid-liquid interface is formed between the liquid gel layer and the solid insulator matrix; a liquid and vacuum interface is formed between the liquid gel layer and the external vacuum; the gel layer comprises insulating oil, nano silicon dioxide, dimethyl dichlorosilane and water; the weight ratio of the insulating oil, the nano silicon dioxide, the dimethyl dichlorosilane and the water in the gel layer is 100:6 to 12:0.5 to 1:0.5 to 1.

2. The vacuum insulator with the gel layer according to claim 1, wherein the weight ratio of the insulating oil, the nano-silica, the dimethyldichlorosilane and the water in the gel layer is 100:8:0.5:0.5.

3. the vacuum insulator with a gel layer according to claim 1, wherein the gel layer is prepared by:

insulating oil, nano silicon dioxide, dimethyl dichlorosilane and water are mixed according to the weight ratio of 100:6 to 12:0.5 to 1:0.5 to 1; then ultrasonic dispersion is carried out by stirring, reaction is carried out for 30 minutes, and the dimethyldichlorosilane is fully hydrolyzed and coupled with the nano silicon dioxide to form a mixed solution; and finally, putting the prepared mixed solution into a vacuum oven, vacuumizing at 50 ℃, and keeping for 8 hours to remove excessive water in the mixed solution, thereby forming gel.

4. The vacuum insulator with the gel layer as claimed in claim 1, wherein the solid insulator substrate is made of organic glass, cross-linked polystyrene, epoxy resin, nylon, polyimide, ceramic or quartz.

5. The vacuum insulator with a gel layer according to claim 1, wherein the thickness of the liquid gel layer is 1-10 mm.

6. A preparation method of a vacuum insulator with a gel layer is characterized by comprising the following steps:

step 1: preparation of the gel

and 2, step: preparing a required insulator matrix by a mechanical processing mode according to the geometric structure and the size of the required insulator;

7. The method for preparing a vacuum insulator with a gel layer according to claim 6, wherein: the insulator matrix is made of organic glass, crosslinked polystyrene, epoxy resin, nylon, polyimide, ceramic or quartz.

8. The method for preparing a vacuum insulator with a gel layer according to claim 6, wherein: the thickness of the gel layer is 1-10 mm.