A nano-silicon modified epoxy resin arc-resistant coating for GIS equipment

Abstract

This invention discloses a nano-silicon modified epoxy resin arc-resistant coating for GIS equipment. The coating comprises bisphenol A type epoxy resin, alicyclic epoxy resin, spherical nano-silicon, spherical nano-SiO₂, aluminum borate whiskers, curing agent, and additives. The nano-silicon and nano-SiO₂ work synergistically to enhance thermal conductivity and homogenize the electric field at the nanoscale. The preparation method includes: surface modification of the nanoparticles; gradient dispersion using a combination of ultrasonic and three-roll milling; electrostatic spraying; and a multi-stage stepped curing process. The coating exhibits an arc erosion time ≥0.5 seconds, a volume resistivity ≥1×10¹⁶ Ω·cm, adhesion ≥15MPa, and a glass transition temperature ≥165℃ under 550kV / 63kA conditions. It also demonstrates excellent resistance to thermal shock and damp heat aging, making it suitable for insulation protection of 550kV and above gas-insulated switchgear and effectively replacing similar imported products.

Description

Technical Field

[0001] This invention relates to the field of arc-resistant coating technology, specifically to an arc-resistant coating for GIS equipment made of nano-silicon modified epoxy resin. Background Technology

[0002] Gas-insulated switchgear (GIS) is widely used in high-voltage power systems, and the arc resistance of its internal insulating components directly affects the safe operation and service life of the equipment. Epoxy resin is commonly used as an insulating coating for GIS equipment due to its excellent insulation, mechanical strength, and chemical corrosion resistance. However, traditional epoxy resin coatings have insufficient arc resistance at voltage levels of 550kV and above, with arc erosion time typically less than 0.2 seconds, failing to meet the 0.5-second requirement of the IEC 62271-203 standard.

[0003] While imported epoxy resin coatings on the market (such as ABB HiCoat550, Siemens EPOXY-Shield, and GENanoGuard) offer certain performance advantages, they still suffer from the following problems: uneven nanoparticle dispersion leading to unstable performance; a trade-off between high glass transition temperature (Tg) and adhesion; high cost of fluorinated modified materials; and significant performance degradation under long-term humid and hot conditions. Therefore, there is an urgent need to develop a domestically produced epoxy resin coating that offers excellent arc resistance, stable overall insulation performance, strong adhesion, and reasonable cost. Summary of the Invention

[0004] (a) Technical issues

[0005] This invention provides a nano-silicon modified epoxy resin arc-resistant coating for 550kV gas-insulated switchgear. Through synergistic modification of nano-silicon and nano-silica in a specific ratio, combined with gradient dispersion and step curing processes, the arc resistance of the coating is significantly improved to over 0.53 seconds. At the same time, it also has excellent dielectric, mechanical and thermal stability, and can effectively replace imported products.

[0006] (II) Technical Content

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a nano-silicon modified epoxy resin arc-resistant coating for GIS equipment, which is composed of the following components: bisphenol A type epoxy resin, alicyclic epoxy resin, spherical nano-silicon, spherical nano-SiO2, aluminum borate whiskers, acid anhydride curing agent, KH-550 silane coupling agent, and leveling agent.

[0008] Furthermore, the arc-resistant coating is composed of the following components by mass percentage: 65% bisphenol A type epoxy resin, 25% alicyclic epoxy resin, 3% spherical nano-silicon, 2% spherical nano-SiO2, 3% aluminum borate whiskers, 22% anhydride curing agent (based on the total mass of bisphenol A type epoxy resin and alicyclic epoxy resin), 0.8% KH-550 silane coupling agent (based on the total mass of nano-silicon and nano-SiO2), and 0.5% leveling agent.

[0009] Furthermore, the spherical nano-silicon has a purity >99.9% and a specific surface area of ​​180–220 m². 2 / g, sphericity >95%, oxygen content <0.5wt%.

[0010] Furthermore, the nano-SiO2 has a hydroxyl content of 300–400 μmol / g and a surface epoxy grafting rate of ≥75%.

[0011] Furthermore, the coating is prepared using a gradient dispersion process, including ultrasonic dispersion and three-roll milling. The ultrasonic power is 800W, the temperature is <40℃, the time is 45min, and the gap between the three rollers is 20μm, so that the D50 particle size of the dispersed nanoparticles is 21.3±1.5nm.

[0012] Furthermore, the curing process of the coating is a stepped curing process: 80℃ / 2h + 120℃ / 1h + 150℃ / 0.5h, with a crosslinking density ≥98%.

[0013] Furthermore, the coating thickness is 120±10μm, and the surface roughness Ra≤0.8μm.

[0014] A method for preparing an arc-resistant coating for GIS equipment using nano-silicon modified epoxy resin includes the following steps: treating nano-silicon and nano-SiO2 with KH-550 silane coupling agent; performing gradient dispersion using ultrasonication and three-roll milling; uniformly mixing the dispersed nano system with epoxy resin, curing agent, aluminum borate whiskers, and leveling agent; applying the coating to the surface of the GIS equipment using electrostatic spraying, followed by step curing to form the coating.

[0015] (III) Technical Effects

[0016] The advantages of this invention compared to the prior art are:

[0017] 1. Significantly improved arc resistance: Through the synergistic effect of nano-silicon and nano-SiO2, the coating achieves an arc erosion resistance time of 0.53±0.05 seconds under 550kV / 63kA conditions, exceeding the IEC standard requirements and being 1.7 times that of competing ABB products and 1.9 times that of Siemens products.

[0018] 2. Excellent dielectric properties: volume resistivity > 1×10⁻⁶ 16Ω·cm, dielectric loss factor <0.008 (50Hz), high dielectric constant stability at high frequencies, and low interface polarization loss.

[0019] 3. Balanced thermo-mechanical properties: The glass transition temperature reaches 168℃, while the adhesion is >17MPa, solving the industry problem of decreased adhesion of high Tg materials; after damp heat aging (85℃ / 85%RH1000h), the dielectric loss increases by <10%, and the estimated service life is >30 years, which is significantly better than the competitors.

[0020] 4. By adopting a gradient dispersion process and a step-curing regime, the uniform dispersion of nanoparticles and the high cross-linking density of the coating are ensured, achieving batch stability. Inorganic nanomaterials are used to replace fluoropolymers, and the cost is only 43% of that of imported competitors, showing good prospects for industrialization and domestic substitution. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Example

[0022] The preparation of an arc-resistant coating for GIS equipment using nano-silicon modified epoxy resin comprises the following steps:

[0023] 1. Raw material preparation

[0024] Bisphenol A type epoxy resin (E-51): 65.0g, epoxy value 0.51eq / 100g.

[0025] Alicyclic epoxy resin (CY-179): 25.0g.

[0026] Spherical nano-silicon powder (20nm): 3.0g, purity >99.9%, specific surface area 200m² 2 / g.

[0027] Spherical nano-silica (20nm): 2.0g, with epoxy groups grafted onto the surface, grafting rate 78%.

[0028] Aluminum borate whiskers: 3.0g.

[0029] Anhydride curing agent (MHHPA): 19.8g (calculated as 22% of the total mass of epoxy resin).

[0030] KH-550 silane coupling agent: 0.04g (calculated as 0.8% of the total mass of nanoparticles).

[0031] Leveling agent (BYK-331): 0.5g.

[0032] 2. Surface treatment of nanopowders

[0033] 3.0g of nano-silica powder and 2.0g of nano-silica were mixed, and 0.04g of KH-550 silane coupling agent and 20mL of anhydrous ethanol were added. The mixture was mechanically stirred at 500r / min for 1 hour in a 50℃ water bath, and then dried in an 80℃ oven for 4 hours to obtain surface-modified composite nanopowder.

[0034] 3. Gradient dispersion process

[0035] The modified composite nanopowder obtained in step 2 was mixed with 90.0 g of epoxy resin (including all of E-51 and CY-179). First, ultrasonic dispersion was performed: using an 800W ultrasonic cell disruptor, under ice-water bath conditions (temperature <40℃), intermittent ultrasonic treatment (2 seconds on, 1 second off) was carried out for 45 minutes. Then, three-roll milling was performed: the pre-dispersed system was transferred to a three-roll mill, with the roller gap set to 20 μm, and milled 5 times in a low-medium-low speed cycle to obtain a uniform nano-modified epoxy resin dispersion.

[0036] 4. Coating preparation

[0037] Add the remaining epoxy resin, 3.0g aluminum borate whiskers, and 0.5g leveling agent (BYK-331) sequentially to the dispersion obtained in step 3, and stir and degas for 30 minutes at 40℃ and a vacuum of -0.095MPa. Before use, add 19.8g of acid anhydride curing agent (MHHPA), stir manually for 5 minutes, then transfer to a vacuum degassing machine and stir at high speed for 10 minutes to obtain the coating to be sprayed.

[0038] 5. Coating preparation and curing

[0039] Electrostatic spraying was used to uniformly apply the above-mentioned coating to the surface of sandblasted 6061 aluminum alloy test pieces (100mm × 100mm × 3mm). Spraying parameters were controlled to achieve a wet film thickness of approximately 150μm. The sprayed test pieces were placed in a clean environment for surface drying for 20 minutes, then transferred to a forced-air drying oven for curing using a stepped temperature increase program: 80℃ for 2 hours, 120℃ for 1 hour, and 150℃ for 0.5 hours. After curing, the coating was cooled to room temperature in the oven, resulting in a dry film thickness of 120±5μm.

[0040] The product test data of the arc-resistant coating prepared in the above embodiments are shown in the table below:

[0041]

[0042] The following table shows the comparative test data of the arc-resistant coatings prepared in the above embodiments:

[0043]

[0044] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown are only one of the embodiments of the present invention. The actual structure is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A nano-silicon modified epoxy resin arc-resistant coating for GIS equipment, characterized in that, It is composed of the following components: bisphenol A type epoxy resin, alicyclic epoxy resin, spherical nano-silicon, spherical nano-SiO2, aluminum borate whiskers, acid anhydride curing agent, KH-550 silane coupling agent, and leveling agent.

2. The arc-resistant coating for GIS equipment made of nano-silicon modified epoxy resin according to claim 1, characterized in that, The arc-resistant coating is composed of the following components by mass percentage: 65% bisphenol A epoxy resin, 25% alicyclic epoxy resin, 3% spherical nano-silicon, 2% spherical nano-SiO2, 3% aluminum borate whiskers, 22% anhydride curing agent (based on the total mass of bisphenol A epoxy resin and alicyclic epoxy resin), 0.8% KH-550 silane coupling agent (based on the total mass of nano-silicon and nano-SiO2), and 0.5% leveling agent.

3. The arc-resistant coating for GIS equipment made of nano-silicon modified epoxy resin according to claim 1, characterized in that, The spherical nano-silicon has a purity >99.9%, a specific surface area of ​​180–220 m² / g, a sphericity >95%, and an oxygen content <0.5 wt%.

4. The arc-resistant coating for GIS equipment made of nano-silicon modified epoxy resin according to claim 1, characterized in that, The nano-SiO2 has a hydroxyl content of 300–400 μmol / g and a surface epoxy grafting rate of ≥75%.

5. The arc-resistant coating for GIS equipment made of nano-silicon modified epoxy resin according to claim 1, characterized in that, The coating is prepared using a gradient dispersion process, including ultrasonic dispersion and three-roll milling. The ultrasonic power is 800W, the temperature is <40℃, the time is 45min, and the gap between the three rollers is 20μm, so that the D50 particle size of the dispersed nanoparticles is 21.3±1.5nm.

6. The arc-resistant coating for GIS equipment made of nano-silicon modified epoxy resin according to claim 1, characterized in that, The curing process of the coating is a stepped curing process: 80℃ / 2h + 120℃ / 1h + 150℃ / 0.5h, with a crosslinking density ≥98%.

7. The arc-resistant coating for GIS equipment made of nano-silicon modified epoxy resin according to claim 1, characterized in that, The coating thickness is 120±10μm, and the surface roughness Ra≤0.8μm.

8. A method for preparing a nano-silicon modified epoxy resin arc-resistant coating for GIS equipment as described in claim 1, characterized in that, Includes the following steps: Nano-silicon and nano-SiO2 were treated with KH-550 silane coupling agent; The nano-system is dispersed by ultrasonic and three-roll milling; the dispersed nano-system is then mixed uniformly with epoxy resin, curing agent, aluminum borate whiskers, and leveling agent; the mixture is then applied to the surface of the GIS equipment using an electrostatic spraying process and cured in stages to form a coating.

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