Preparation process of silicon grease material for high-voltage cable surface moisture-proof and aging prevention

Abstract

This invention relates to the field of high-voltage insulation materials and X-ray equipment maintenance technology, and discloses a process for preparing a silicone grease material for moisture-proofing and anti-aging of high-voltage cable surfaces. The basic raw materials of the silicone grease material are in the following mass ratios: 70-80 parts dimethyl silicone oil; 8-12 parts fumed silica; 3-6 parts moisture-proof modifier; 2-4 parts organic anti-aging agent; 1-3 parts crosslinking agent; and 4-7 parts nano-alumina insulating filler. The silicone grease material is prepared through mixing, stirring, degassing, and homogenization steps. In application, the high-voltage cable is coated with the silicone grease material for protection, and a composite protective structure is formed by using a target material impregnated with silicone grease-impregnated paper. This compensates for the shortcomings of traditional single paper insulation protection, such as poor withstand voltage and easy breakdown, thereby effectively blocking the high-voltage arc discharge path of the X-ray tube, eliminating high-voltage arc breakdown faults in the equipment, and achieving dual protection for both the high-voltage cable and the X-ray tube target material. This makes it suitable for X-ray high-voltage equipment under different voltage and humidity conditions.

Description

Technical Field

[0001] This invention relates to the field of high-voltage insulation materials and X-ray equipment maintenance technology, specifically to a process for preparing a silicone grease material for moisture-proofing and anti-aging of high-voltage cable surfaces. Background Technology

[0002] High-voltage cables, operating for extended periods in substations, medical X-ray equipment, and industrial high-voltage power supplies, are susceptible to moisture erosion, leading to decreased insulation resistance and phenomena such as mold growth and electrochemical corrosion. In severe cases, this can cause surface flashover or breakdown accidents. While existing high-voltage silicone greases offer some waterproofing, they generally suffer from the following shortcomings: uneven dispersion of thickeners in traditional silicone greases, resulting in easy flow or cracking, and a significant decrease in moisture resistance over time; a lack of anti-aging components, leading to accelerated aging of the silicone grease itself and the cable insulation layer; and in high-electric-field environments such as X-ray tubes, the outer ring of the target material is often reinforced with corrugated insulating paper, but corrugated paper is prone to moisture absorption, and ordinary silicone grease cannot effectively fill its fiber pores. Prolonged exposure to moisture causes a sharp drop in insulation strength, increasing the risk of high-voltage arc breakdown and shortening the target material's lifespan. Therefore, there is an urgent need to develop a silicone grease material that combines excellent moisture resistance, mold resistance, anti-aging properties, and high insulation strength, and to optimize its preparation process to simultaneously meet the application requirements of high-voltage cable surface protection and X-ray tube target material corrugated paper-reinforced insulation. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a process for preparing silicone grease materials for moisture-proofing and anti-aging of high-voltage cable surfaces. This process offers advantages such as high hydrophobicity, long-term anti-aging properties, dense insulation, absence of bubble defects, and compatibility with corrugated paper impregnation reinforcement. It solves the problems of poor moisture-proof durability, easy mold growth, and short target life caused by moisture-induced breakdown of corrugated paper in existing silicone greases.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a process for preparing a silicone grease material for moisture-proofing and anti-aging of high-voltage cable surfaces, comprising the following steps:

[0007] Step 1: Preparation of basic raw materials: Prepare dimethyl silicone oil, fumed silica, moisture-proof modifier, organic anti-aging agent, crosslinking agent and nano alumina insulating filler as raw materials;

[0008] Step 2, Base Material Mixing: Dimethyl silicone oil, fumed silica and nano alumina insulating filler are stirred at high speed under heating conditions to form a uniform paste-like base material;

[0009] Step 3: Addition of functional additives: Continue to add moisture-proof modifiers, organic anti-aging agents and crosslinking agents to the paste base, and stir evenly to obtain silicone grease colloid;

[0010] Step 4: Vacuum degassing and purification treatment: Transfer the well-stirred silicone grease into a vacuum degassing machine and perform vacuum degassing on the silicone grease under set conditions;

[0011] Step 5, Homogenization and Packaging: After removing air bubbles from the silicone grease colloid, it is homogenized by a homogenizer. After the material is discharged, it is naturally cooled to ≤38℃ and packaged in a sealed barrel with a stainless steel liner.

[0012] Preferably, the mass fraction range of the basic raw materials in step one is as follows: 70-80 parts dimethyl silicone oil; 8-12 parts fumed silica; 3-6 parts moisture-proof modifier; 2-4 parts organic anti-aging agent; 1-3 parts crosslinking agent; and 4-7 parts nano-alumina insulating filler.

[0013] Preferably, the viscosity range of the dimethyl silicone oil is 400-480 mm² / s; the specific surface area of ​​the fumed silica is controlled at 150-200 m² / g; the mass percentage of nano-alumina in the nano-alumina insulating filler is 8%-10%, and the median particle size of the nano-alumina particles is controlled between 30-50 nm.

[0014] Preferably, the moisture-proof modifying agent is selected from zinc stearate or calcium stearate; the organic anti-aging agent is selected from antioxidant 1010 or antioxidant 1076; and the crosslinking agent is selected from tetraethyl orthosilicate, methyltriethoxysilane or vinyltriethoxysilane.

[0015] Preferably, in step two, the base material mixing process is as follows: dimethyl silicone oil is added to the reactor, the temperature is raised to 110-115°C, and fumed silica and nano-alumina insulating filler are added in 3-4 batches at a speed of 1000-1200 rpm, with an interval of 8-10 minutes between each addition. After the addition is complete, the mixture is stirred continuously for 20-30 minutes while maintaining a constant temperature. The mixture is then vacuum dehydrated for 8-10 minutes under a vacuum of -0.08 to -0.1 MPa.

[0016] Preferably, in step three, the functional additives are added as follows: the temperature is lowered to 80-90°C, and the moisture-proof modifier and the organic anti-aging agent are added sequentially. The mixture is stirred at 600-800 rpm for 15-20 minutes, and then the crosslinking agent is added dropwise, with the dropping rate controlled at 1-2 drops / second. After the addition is complete, the mixture is stirred for another 10-15 minutes.

[0017] Preferably, the vacuum degassing and purification treatment conditions in step four are as follows: vacuum degree -0.08 to -0.1 MPa, degassing temperature 45 to 60°C, and continuous degassing for 20 to 35 minutes.

[0018] Preferably, the homogenization conditions in step five are set as follows: homogenization speed 4000-5000 rpm, time 30-45 minutes.

[0019] Preferably, the silicone grease material is applied to the surface of the high-voltage cable to form a protective layer after coating.

[0020] Preferably, the silicone grease material is used to impregnate the walnut insulating paper layer, and the silicone grease-impregnated walnut insulating paper layer is placed between the outer ring of the target material and the wall of the X-ray tube.

[0021] Compared with the prior art, the present invention provides a process for preparing silicone grease material for moisture-proofing and anti-aging of high-voltage cable surfaces, which has the following beneficial effects:

[0022] 1. This invention uses a special dimethyl silicone oil with a viscosity of 400-480 mm² / s as a base, combined with hydrophobic fumed silica and nano-alumina composite fillers, and specifies precise raw material ratios and parameters. The specific surface area of ​​the fumed silica is controlled at 150-200 m² / g and the particle size is controlled at 7-40 nm. The median particle size of the nano-alumina is controlled at 30-50 nm, and the mass percentage of nano-alumina in the silicone grease is 8%-10%. The combination of these three raw materials can significantly improve the density and structural stability of the silicone grease colloid, effectively sealing the micropores in the insulation layer of high-voltage cables, thereby further improving the high-voltage insulation performance and hydrophobic moisture-proof ability of the silicone grease, and ultimately suppressing the problems of high-voltage cables becoming damp and moldy, and the aging and damage of the insulation layer from the root cause.

[0023] 2. This invention avoids the defects of additive failure and local crosslinking clumping caused by high temperature by using a low-temperature addition of functional additives and a low-speed controlled dripping of crosslinking agents. It ensures that the moisture-proof additives and anti-aging agents are uniformly dispersed in the colloid. Combined with vacuum degassing and high-speed homogenization curing processes, the penetration of the finished product is precisely controlled, so that the silicone grease has both flexibility and adhesion. It is not easy to crack, fall off or fail under long-term high-voltage conditions, which greatly extends the protection cycle of high-voltage cables and reduces the daily operation and maintenance costs of equipment.

[0024] 3. This invention innovatively adopts a composite protection structure for the target material, which combines high-voltage cable coating with silicone grease protection with silicone grease-impregnated varnish paper. This structure compensates for the shortcomings of traditional single varnish paper insulation protection, such as poor withstand voltage and easy breakdown. It effectively blocks the high-voltage arc discharge path of the X-ray tube, eliminates high-voltage arc breakdown faults in the equipment, significantly reduces the loss rate of the X-ray tube target material, and achieves dual protection for both the high-voltage cable and the X-ray tube target material. This makes it suitable for X-ray high-voltage equipment under different voltage and humidity conditions. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the preparation process of the silicone grease material of this invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figure 1 A process for preparing a silicone grease material for moisture and aging prevention on the surface of high-voltage cables includes the following steps:

[0028] Step 1: Basic Raw Material Preparation: Prepare dimethyl silicone oil, fumed silica, moisture-proof modifier, organic anti-aging agent, crosslinking agent and nano alumina insulating filler as raw materials. The raw materials selected in this step, after being matched in a set ratio, can withstand high temperature and high voltage insulation, and prepare silicone grease base colloid, thereby ensuring the high voltage insulation and moisture-proof substrate performance of the final material.

[0029] Step 2, Base Material Mixing: Dimethyl silicone oil, fumed silica and nano alumina insulating filler are stirred at high speed under heating conditions to form a uniform paste-like base material;

[0030] Step 3: Addition of functional additives: Continue to add moisture-proof modifiers, organic anti-aging agents and crosslinking agents to the paste base, stir evenly to obtain silicone grease colloid, which gives the silicone grease long-term moisture-proof, mildew-proof and anti-aging properties;

[0031] Step 4: Vacuum degassing and purification treatment: Transfer the well-stirred silicone grease into a vacuum degassing machine and perform vacuum degassing on the silicone grease under set conditions to remove internal air bubbles and trace amounts of water vapor, thereby improving the density and moisture-proof insulation properties of the silicone grease.

[0032] Step 5, Homogenization and Packaging: After removing air bubbles from the silicone grease colloid, it is homogenized using a homogenizer to improve the uniformity and fineness of the final material dispersion. After discharge, the material is naturally cooled to ≤38℃ and packaged in sealed barrels with stainless steel linings. Each barrel has a net weight of 2-3 kg. The humidity of the packaging environment is ≤50% to avoid dust contamination. It is stored in a sealed container at 5-30℃. The sealed packaging effectively prevents moisture absorption and contamination.

[0033] Specifically, the mass fraction range of the basic raw materials in step one is as follows: 70-80 parts dimethyl silicone oil; 8-12 parts fumed silica (hydrophobic); 3-6 parts moisture-proof modifier; 2-4 parts organic anti-aging agent; 1-3 parts crosslinking agent (methyltriethoxysilane); and 4-7 parts nano alumina insulating filler. All raw materials are selected from industrial high-voltage equipment grade, free of impurities and acid / alkali residues, suitable for high-voltage electric field environments, and prevent corrosion of the surface insulation of high-voltage cables.

[0034] Specifically, the viscosity range of dimethyl silicone oil is 400–480 mm² / s. This viscosity balances the fluidity, film-forming properties, and adhesion of the silicone grease, ensuring uniform coating without accumulation or flow, and forming a dense and stable insulating and moisture-proof film layer, suitable for the high-voltage electric field environment of X-ray equipment. The fumed silica is hydrophobic, with a specific surface area controlled at 150–200 m² / g and a particle size controlled at 7–40 nm. The nano-alumina insulating filler has a nano-alumina mass ratio of 8%–10%, and the median particle size (D50) of the nano-alumina particles is controlled between 30 and 50 nm. This range has excellent particle dispersibility, which can accurately fill the micropores of silicone grease colloid and cable insulation layer, thereby significantly improving the overall insulation strength and structural density. In addition, all raw materials are selected from industrial high-voltage equipment grade, free of impurities and acid / alkali residues, suitable for high-voltage electric field environments, and avoid corrosion of the surface insulation of high-voltage cables.

[0035] Specifically, the moisture-proof modifying agent is selected from zinc stearate or calcium stearate; the organic anti-aging agent is selected from antioxidant 1010 or antioxidant 1076; the crosslinking agent is selected from tetraethyl orthosilicate, methyltriethoxysilane or vinyltriethoxysilane; all dry raw materials are dried in a vacuum drying oven at 70-80℃ for 1.5-2 hours, with a moisture content ≤0.05%.

[0036] Specifically, the roles of the raw materials are shown in the table below:

[0037] Table 1

[0038] Dimethyl silicone oil (viscosity 400~480mm² / s) The base oil provides the silicone grease with fluidity, film-forming properties, and adhesion, ensuring uniform application and forming a dense and stable insulating and moisture-proof film. Fumed silica (hydrophobic type, specific surface area 150-200 m² / g, particle size 7-40 nm) Thickeners and thixotropic agents increase the viscosity and thixotropic properties of silicone grease, preventing it from flowing and enhancing its structural stability. Moisture-proofing modifier (zinc stearate or calcium stearate) Enhance the hydrophobicity and moisture-proof properties of silicone grease to prevent moisture from penetrating the surface of high-voltage cables. Organic anti-aging agents (antioxidant 1010 or antioxidant 1076) Inhibits the aging and oxidation of silicone grease and cable insulation, extends service life, and prevents surface mold growth. Crosslinking agent (ethyl orthosilicate, methyltriethoxysilane, or vinyltriethoxysilane) Promotes appropriate cross-linking of silicone oil, improving the heat resistance, film-forming strength, and stability of silicone grease under high pressure.

[0039] Specifically, in step two, the base material mixing process is as follows: Dimethyl silicone oil is added to the reactor, and the temperature is raised to 110-115℃. Fumed silica and nano-alumina insulating filler are added in 3-4 portions at a speed of 1000-1200 rpm, with an interval of 8-10 minutes between each addition. After the addition is complete, the mixture is stirred continuously for 20-30 minutes to ensure that the fumed silica and nano-alumina insulating filler are completely dispersed and the system is in the form of a paste. The temperature is kept constant, and the mixture is vacuum dehydrated for 8-10 minutes under a vacuum degree of -0.08 to -0.1 MPa.

[0040] The advantages are: by adding thickener and insulating filler in stages, agglomeration is effectively avoided, ensuring that fumed silica and nano alumina are evenly dispersed in silicone oil to form a stable paste base; vacuum dehydration can effectively remove residual moisture from the raw materials, thereby preventing the generation of bubbles or water vapor breakdown under high pressure.

[0041] Specifically, in step three, the functional additives are added as follows: the temperature is lowered to 80-90℃, and the moisture-proof modifier and organic anti-aging agent are added in sequence. The mixture is stirred at 600-800 rpm for 15-20 minutes, and then the crosslinking agent is added drop by drop, with the dropping rate controlled at 1-2 drops / second. After the addition is complete, the mixture is stirred for 10-15 minutes.

[0042] The advantages are: by adding moisture-proof additives and anti-aging agents under low temperature conditions, the active functions can be avoided by high temperature; the addition of crosslinking agents can control the degree of crosslinking, which can improve the adhesion and heat resistance of silicone grease without causing excessive crosslinking and loss of flexibility.

[0043] Specifically, the vacuum degassing and purification treatment conditions in step four are as follows: set the vacuum degree to -0.08 to -0.1 MPa, the degassing temperature to 45 to 60°C, and continue degassing for 20 to 35 minutes. Under these conditions, the air, residual moisture, and volatile impurities inside the colloid can be completely removed, ensuring that the molded silicone grease has a dense structure without pore defects, and avoiding insulation failure and water vapor penetration under high voltage conditions.

[0044] The advantages are: by vacuum degassing at a medium temperature of 45-60℃, not only can the air, residual moisture and volatile impurities inside the grease be completely removed, but the component decomposition caused by high temperature can also be avoided, ensuring that the molded silicone grease has a dense structure without pore defects, thereby preventing insulation failure and water vapor penetration under high voltage conditions.

[0045] Specifically, the homogenization conditions in step five are set as follows: homogenization speed 4000-5000 rpm, time 30-45 minutes, and sampling and testing after homogenization. The samples should be free of visible air bubbles and the penetration (25℃, 0.1mm) should be 250-300.

[0046] The advantages are: high-speed homogenization (4000-5000 rpm) enables the material to be uniformly dispersed at the nanoscale, and the penetration is controlled at 250-300 (25℃, 0.1mm) to ensure that the silicone grease has a suitable softness and hardness—it is easy to apply, does not flow, and has no visible air bubbles, thus ensuring batch stability.

[0047] Specifically, silicone grease is applied to the surface of high-voltage cables, forming a dense protective layer to prevent moisture intrusion and surface mold growth.

[0048] The advantages are: by coating the surface of high-voltage cables with silicone grease, a dense protective layer is formed, which has excellent hydrophobicity and anti-aging properties, can prevent moisture intrusion for a long time, avoid mold and electrochemical corrosion on the surface of high-voltage cables, and improve the surface flashover voltage.

[0049] Specifically, silicone grease is used to enhance the insulation performance of the outer wainscoting of the X-ray tube target; specifically, a layer of wainscoting impregnated with silicone grease is added between the outer ring of the target and the wall of the X-ray tube to block the high-voltage arc path, thereby extending the life of the target.

[0050] The advantages are: the varnish-impregnated paper fills the pores between paper fibers, which can significantly improve the voltage resistance of the insulating paper and block the path of high voltage arc from the outer ring of the target to the tube wall, thereby effectively extending the life of the X-ray tube target.

[0051] The silicone grease material prepared according to this invention is applied in the following environments:

[0052] Example 1

[0053] A conventional industrial X-ray inspection device was selected. The device operates at a high voltage of 60kV and in a normal temperature and high humidity environment (ambient humidity 75%~85%RH). The surface of the high-voltage cable of the device was coated with the silicone grease prepared in this process, with a coating thickness of 0.3mm. At the same time, the outer ring of the X-ray tube target was wrapped with silicone grease-impregnated corrugated paper. The device was run continuously for 12 months, and the aging and mold growth of the cable, as well as the target material loss and the number of arc breakdown faults, were recorded.

[0054] Example 2

[0055] Heavy-duty X-ray flaw detection equipment was selected. The equipment operates at a high voltage of 100kV in a humid and dusty workshop environment (ambient humidity 65%~75%RH). The high-voltage cable is coated with 0.4mm thick silicone grease, and the outer ring of the target is covered with silicone grease-impregnated corrugated paper. The equipment operates intermittently with high-frequency start and stop, with a cumulative operating time of 12 months. Data on high-voltage faults, cable aging, and target wear were collected.

[0056] Example 3

[0057] High-precision medical X-ray equipment was selected, with a working voltage of 150kV and a constant temperature and humidity environment (50%~60%RH). The high-voltage cable was coated with 0.25mm thick silicone grease and was protected with silicone grease-impregnated corundum paper target material. The equipment was operated stably for 12 months to test the cable insulation performance, target loss rate and equipment breakdown failure rate.

[0058] Comparative Example 1

[0059] The equipment model, operating conditions, and operating time are completely consistent with those of Example 1. The high-voltage cables are only routinely cleaned and maintained, without being coated with silicone grease for protection. The X-ray tube target material is only covered with ordinary dry varnish paper and is not impregnated with silicone grease.

[0060] Comparative Example 2

[0061] The equipment model, operating conditions, and operating time are completely consistent with those of Example 2. The high-voltage cables are coated with commercially available high-voltage silicone grease, and the X-ray tube target is covered with ordinary insulating oil paper. The modified protection method of this process is not used.

[0062] Comparative Example 3

[0063] The equipment model, operating conditions, and operating time are completely consistent with those of Example 3. The high-voltage cable is coated with the silicone grease of this process, and no additional corundum paper insulation protective layer is added to the X-ray tube target material.

[0064] The performance of the three sets of embodiments and the three sets of comparative embodiments were uniformly tested and compared. The four core indicators of high-voltage cable mold rate, insulation strength retention rate, target material loss rate, and high-voltage arc breakdown failure rate were statistically analyzed. The specific comparison data are shown in Table 2 below.

[0065] Table 2

[0066] Example 1 0.8 98.2 1.1 0 Example 2 1.2 97.5 1.5 0 Example 3 0.5 99.1 0.8 0 Comparative Example 1 18.6 72.3 8.9 12.7 Comparative Example 2 7.3 85.6 4.2 5.3 Comparative Example 3 0.6 98.5 6.7 8.2

[0067] Analysis of Table 2 shows that compared to unprotected, ordinary silicone grease protection, and single protection methods, the composite protection scheme of silicone grease prepared by this process combined with silicone grease-impregnated varnish paper has significant advantages. Among them, Comparative Example 1, which was unprotected, suffered from the most severe problems of cable mold growth, insulation attenuation, target material loss, and breakdown failure. Comparative Example 2, which used commercially available ordinary silicone grease, had a significantly weaker protection effect than the product prepared by this process. Comparative Example 3, which only provided cable protection without target material varnish paper protection, had excellent cable protection effect, but the problem of high-voltage breakdown loss of the target material could not be solved. Under different voltages and operating conditions, all three sets of examples maintained extremely low rates of cable mold growth and target material loss, with a high-voltage arc breakdown failure rate of 0. Moreover, the cable insulation strength retention rate was extremely high after long-term operation, proving that this silicone grease material has excellent moisture-proof, anti-aging, and high-voltage insulation performance. At the same time, the dual protection mode of cable coating + target material varnish paper impregnation can be adapted to various X-ray high-voltage equipment operating conditions, comprehensively solving the problems of equipment moisture-induced mold growth, insulation failure, arc breakdown, and excessively rapid target material loss.

[0068] In summary, this invention optimizes the raw material ratio, preparation process, and parameter system of high-voltage protective silicone grease. Through precise multi-stage feeding, low-temperature cross-linking, vacuum degassing, and high-speed homogenization, it prepares a specialized silicone grease material with high density, strong adhesion, excellent moisture resistance, anti-aging properties, and pressure resistance. Simultaneously, it innovatively employs a dual-protection structure of high-voltage cable coated with silicone grease and X-ray tube target silicone grease impregnated with corrugated paper. This comprehensively solves the problems of high-voltage cable dampness, mold growth, and aging in X-ray high-voltage equipment, high-voltage arc breakdown in the X-ray tube, and short target life. The material preparation process is stable, effectively reducing equipment failure rates and maintenance costs, and extending the service life of high-voltage cables and X-ray tube targets.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for preparing a silicone grease material for moisture-proofing and anti-aging of high-voltage cable surfaces, characterized in that, Includes the following steps: Step 1: Preparation of basic raw materials: Prepare dimethyl silicone oil, fumed silica, moisture-proof modifier, organic anti-aging agent, crosslinking agent and nano alumina insulating filler as raw materials; Step 2, Base Material Mixing: Dimethyl silicone oil, fumed silica and nano alumina insulating filler are stirred at high speed under heating conditions to form a uniform paste-like base material; Step 3: Addition of functional additives: Continue to add moisture-proof modifiers, organic anti-aging agents and crosslinking agents to the paste base, and stir evenly to obtain silicone grease colloid; Step 4: Vacuum degassing and purification treatment: Transfer the well-stirred silicone grease into a vacuum degassing machine and perform vacuum degassing on the silicone grease under set conditions; Step 5, Homogenization and Packaging: After removing air bubbles from the silicone grease colloid, it is homogenized by a homogenizer. After the material is discharged, it is naturally cooled to ≤38℃ and packaged in a sealed barrel with a stainless steel liner.

2. The process for preparing a silicone grease material for preventing moisture and aging on the surface of a high-voltage cable according to claim 1, characterized in that, The mass fraction range of the basic raw materials in step one is as follows: 70-80 parts dimethyl silicone oil; 8-12 parts fumed silica; 3-6 parts moisture-proof modifier; 2-4 parts organic anti-aging agent; 1-3 parts crosslinking agent; and 4-7 parts nano-alumina insulating filler.

3. The process for preparing a silicone grease material for preventing moisture and aging on the surface of a high-voltage cable according to claim 2, characterized in that, The viscosity range of the dimethyl silicone oil is 400-480 mm² / s; the specific surface area of ​​the fumed silica is controlled at 150-200 m² / g; the mass proportion of nano-alumina in the nano-alumina insulating filler is 8%-10%, and the median particle size of the nano-alumina particles is controlled between 30-50 nm.

4. The process for preparing a silicone grease material for preventing moisture and aging on the surface of a high-voltage cable according to claim 2, characterized in that, The moisture-proof modifier is selected from zinc stearate or calcium stearate; the organic anti-aging agent is selected from antioxidant 1010 or antioxidant 1076; and the crosslinking agent is selected from tetraethyl orthosilicate, methyltriethoxysilane or vinyltriethoxysilane.

5. The process for preparing a silicone grease material for preventing moisture and aging on the surface of a high-voltage cable according to claim 1, characterized in that, In step two, the base material mixing process is as follows: Dimethyl silicone oil is added to the reactor, the temperature is raised to 110-115°C, and fumed silica and nano-alumina insulating filler are added in 3-4 batches at a speed of 1000-1200 rpm, with an interval of 8-10 minutes between each addition. After the addition is complete, the mixture is stirred continuously for 20-30 minutes while maintaining a constant temperature. The mixture is then vacuum dehydrated for 8-10 minutes under a vacuum of -0.08 to -0.1 MPa.

6. The process for preparing a silicone grease material for preventing moisture and aging on the surface of a high-voltage cable according to claim 1, characterized in that, In step three, the functional additives are added as follows: the temperature is lowered to 80-90℃, and the moisture-proof modifier and organic anti-aging agent are added in sequence. The mixture is stirred at 600-800 rpm for 15-20 minutes, and then the crosslinking agent is added drop by drop, with the dropping rate controlled at 1-2 drops / second. After the addition is complete, the mixture is stirred for 10-15 minutes.

7. The process for preparing a silicone grease material for moisture-proofing and anti-aging of high-voltage cable surfaces according to claim 1, characterized in that, The vacuum degassing and purification conditions in step four are as follows: vacuum degree -0.08 to -0.1 MPa, degassing temperature 45 to 60°C, and continuous degassing for 20 to 35 minutes.

8. The process for preparing a silicone grease material for moisture-proofing and anti-aging of high-voltage cable surfaces according to claim 1, characterized in that, The homogenization conditions in step five are set as follows: homogenization speed 4000-5000 rpm, time 30-45 minutes.

9. The process for preparing a silicone grease material for preventing moisture and aging on the surface of a high-voltage cable according to claim 1, characterized in that, The silicone grease material is applied to the surface of high-voltage cables, forming a protective layer after coating.

10. The process for preparing a silicone grease material for preventing moisture and aging on the surface of a high-voltage cable according to claim 1, characterized in that, The silicone grease material is used to impregnate the walnut insulating paper layer, and the silicone grease-impregnated walnut insulating paper layer is placed between the outer ring of the target material and the wall of the X-ray tube.

Images