Method for evaluating the hydrophobicity migration of a pollution flash prevention coating by in situ infrared spectroscopy

Abstract

This invention provides a method for testing the hydrophobicity and evaluating the hydrophobic migration of an anti-flashover rubber insulating coating, comprising the following steps: preparing an anti-flashover coating and incorporating a small molecule indicator therein; applying the anti-flashover coating to a glass plate to obtain an anti-flashover coating with a thickness of 0.3~0.5 mm, curing and drying to obtain a glass plate / anti-flashover coating; pre-treating the contaminant by passing it through a 200-sieve, uniformly dispersing the sieve material in deionized water or ethanol, and then spraying it onto the surface of the anti-flashover coating, and drying it thoroughly to obtain a glass plate / anti-flashover coating / contaminant; depositing a metal film on the contaminant surface of the glass plate / anti-flashover coating / contaminant as a reflective layer for infrared incident light and a plasma enhancer to obtain a glass plate / anti-flashover coating / contaminant / metal film; and performing hydrophobicity testing and evaluating hydrophobic migration. This method is simple and rapid, and is expected to be widely used.

Description

Technical Field

[0001] This invention belongs to the technical field of hydrophobic migration testing of electrical external insulation coatings, and in particular, a method for testing and evaluating the hydrophobic migration of anti-flashover rubber insulation coatings. Background Technology

[0002] The power system is the infrastructure of the power industry, playing a crucial role in ensuring national economic development. Under complex, especially polluted, weather conditions (fog, haze, rain, snow, etc.), high-voltage transmission and transformation equipment is highly susceptible to flashover. It is understood that thousands of flashover trips occur in the national power grid annually, sometimes almost causing the disconnection of provincial power grids. To ensure stable grid operation, anti-flashover coatings are widely used to protect insulators, switches, and other high-voltage transmission and transformation equipment. Among anti-flashover coatings, room temperature vulcanizing (RTV) silicone rubber coatings are widely promoted and applied in the power industry due to their ease of application, good hydrophobicity, and high flashover voltage.

[0003] Besides hydrophobicity, another important indicator for evaluating RTV silicone rubber coatings is hydrophobic migration, that is, the ability of the coating's own hydrophobicity to migrate to the contaminants when the surface is contaminated. Only coatings with hydrophobic migration can operate safely in actual working conditions and prevent flashover. Traditional methods for evaluating the hydrophobicity and hydrophobic migration of silicone rubber insulating coatings (GB / T19519-2014) involve applying contaminants or simulated contaminants to the coating surface and then measuring the contact angle-time curve of the contaminated coating, or performing hydrophobicity apparent grading by spraying multiple samples with water multiple times (DL / T627-2018). While these methods are widely used, they are labor-intensive and have low repeatability. Currently, no method for evaluating the hydrophobic migration of anti-flashover coatings using spectroscopic methods has been reported. In other fields, national invention patent CN 114252409 A discloses a method for checking the gelation time of powder coatings, CN 104198432 B discloses a method for identifying the brand of fire-retardant coatings for steel structures, and CN 103604771 A discloses a method for identifying the type of water-based wall coating emulsion. However, these methods do not involve hydrophobicity evaluation and are all non-in-situ.

[0004] Infrared spectroscopy utilizes the interaction of atoms and molecules with infrared light (wavenumbers 800–4000 cm⁻¹). -1Infrared spectroscopy is a molecular spectrum that identifies chemical bonds and functional groups of substances by analyzing the characteristic vibrational frequencies of molecules, making it suitable for identifying compounds, especially organic compounds. Based on the characteristic infrared spectra (fingerprints) and signal strength of organic compounds, the characteristic functional groups and their content can be identified. Therefore, using infrared spectroscopy to identify RTV silicone rubber coatings and organic matter migrating from the coating to the contaminated surface is theoretically feasible. It is generally believed that the hydrophobic migration of RTV silicone rubber coatings originates from the migration of small organic molecules from the interior of the coating to the contaminated surface, imparting hydrophobicity to the contaminated surface. The infrared spectral identification of these molecules has been applied in related studies (IEEE Trans. Dielect. Elec. Insulation 2017 24:1057, IEEE Trans. Power Delivery 2003 18:506). However, there are currently no reports on evaluating the hydrophobicity and hydrophobic migration of anti-flashover coatings using the molecular spectra of these molecules. Summary of the Invention

[0005] This invention discloses a simple and rapid method for evaluating the hydrophobicity and hydrophobic migration of an anti-flashover coating by in-situ tracking the infrared spectral signals of organic molecules in the dirt of the anti-flashover coating.

[0006] To achieve the above-mentioned technical objectives, the present invention provides the following technical solution:

[0007] A method for in-situ infrared spectroscopy testing of organic matter in dirt on anti-flashover coatings includes the following steps:

[0008] (1) Prepare an anti-flashover coating and incorporate a small molecule indicator into it;

[0009] (2) Apply the anti-flashover coating to the glass plate to obtain an anti-flashover coating with a thickness of 0.3-0.5 mm. Allow it to cure and dry to obtain the glass plate / anti-flashover coating. Figure 1 As shown;

[0010] (3) For the pretreatment of dirt, pass it through a 200-sieve, and disperse the sieve material evenly in deionized water or ethanol. Then spray it onto the surface of the anti-flashover coating. After it is fully dried, you get glass plate / anti-flashover coating / dirt.

[0011] (4) On the dirty surface of glass plate / anti-flashover coating / dirt, a metal film is deposited as a reflective layer for infrared incident light and a plasma enhancer to obtain glass plate / anti-flashover coating / dirt / metal film.

[0012] (5) Place the glass plate / anti-flashover coating / dirt / metal film into the sample chamber of the attenuated total reflection Fourier transform infrared spectrometer (ATR-FTIR), with the metal film in close contact with the detector of the ATR-FTIR.

[0013] (6) Set the ambient temperature and humidity, age the glass plate / anti-flashover coating / dirt / metal film for a certain period of time, and then use ATR-FTIR to test the FTIR of dirt during the aging process of the anti-flashover coating in situ;

[0014] (7) Analyze the obtained FTIR to identify the organic components that have migrated into the filth.

[0015] Furthermore, the aforementioned anti-flashover coating refers to silicone coating or fluorine coating.

[0016] Furthermore, the small molecule indicator refers to an indicator molecule that is compatible with the anti-flashover coating and can diffuse to the surface of the anti-flashover coating, with a molecular weight <10000g / mol and a viscosity <1000mPa.s.

[0017] Furthermore, the aforementioned contamination refers to simulated contamination or contamination of the insulator coating in a power system, with a coating amount of 0–3 mg / cm³. 2 .

[0018] Furthermore, the simulated filth refers to diatomaceous earth, sodium chloride, or a mixture of both.

[0019] Furthermore, the aforementioned metal thin film refers to a nanoparticle thin film of platinum, gold, silver, copper, etc., with a thickness of 6–10 nm.

[0020] A method for in-situ infrared spectroscopy testing the hydrophobic migration properties of anti-flashover coatings includes the following steps:

[0021] (1) Using the above method, six identical glass plates / anti-flashover coatings / dirt / metal films were prepared by cutting, and the serial numbers were recorded as #1, #2, #3, #4, #5, and #6.

[0022] (2) Every 1 hour, the FTIR of glass plates #1, #2, and #3 / anti-flashover coating / dirt / metal film was tested using the above method. The integral area corresponding to the first characteristic peak of the small molecule indicator was identified from the results. The average of the three values ​​was recorded as S′. i To remove the coating background S b The influence of S i =S′ i -S b S b =S1; (i represents the i-th).

[0023] (3) Similarly, every 1 hour, the contact angles of glass plates #4, #5, and #6 / anti-flashover coating / dirt / metal film were tested using the traditional method (GB / T19519-2014). The average of the three was recorded as θ. i (i represents the i-th digit)

[0024] (4) Until the Nth h, S i θ i When all values ​​tend to stabilize, Nh is called the characteristic time of the hydrophobic migration property of the anti-flashover coating.

[0025] (5) Summary and tabulation:

[0026]

[0027] Plot the curve θ i -i、S i -i, calculate the slope k of each of the three curves. θ k s That is, the hydrophobic migration rate; find their respective inflection points θ c S c That is, the characteristic hydrophobic angle. Definition:

[0028] Hydrophobic migration rate correction factor: k′=k θ / k s

[0029] Characteristic hydrophobic angle correction factor: θ′=θ c / S c

[0030] (6) Fix the small molecule indicator and test the effect of coating thickness h on hydrophobic migration rate.

[0031] Change the coating thickness h, repeat steps (1)-(5), and measure S. i -i, to obtain k s S c and its correction value k′k s ,θ′S c This avoids directly measuring θ i -i.

[0032] (7) Fix small molecule indicators and test the effect of dirt density f on hydrophobic migration rate.

[0033] Change the dirt density f, repeat steps (1)-(5), and measure S. i -i, to obtain k s S c and its correction value k′k s ,θ′S c This avoids directly measuring θ i -i.

[0034] Beneficial effects:

[0035] The test results have good reliability and super repeatability; this method can realize in-situ testing of dirt and its basic components during the aging process of anti-flashover coating, and is easy to operate; in addition, it can more intuitively show the influence of coating thickness and dirt density on hydrophobic migration rate. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating the principle of in-situ infrared spectroscopy testing of organic matter in the anti-flashover coating of the present invention. Detailed implementation method:

[0037] The following is in conjunction with the appendix Figure 1 The feasibility of the technical solution of the present invention is illustrated through these embodiments, but the present invention is not limited to these embodiments.

[0038] Example 1:

[0039] A method for in-situ infrared spectroscopy testing of organic matter in dirt on anti-flashover coatings includes the following steps:

[0040] (1) PDMS organosilicon anti-flashover coating was prepared using 5000 mPa·s hydroxyl-terminated polydimethylsiloxane (PDMS) as raw rubber, methyl tributanone oxime silane as crosslinking agent, stannous octoate as catalyst, and 600 mPa·s methyl fluorosilicone oil as small molecule indicator.

[0041] (2) The above coating is applied to a 5mm thick quartz glass plate to obtain a 0.4mm thick anti-flashover coating. The coating is cured at 25℃ for 24 hours and then dried to obtain a glass plate / anti-flashover coating.

[0042] (3) Commercial diatomaceous earth was ball-milled for 4 hours, passed through a 200-sieve, and the sieved material was ultrasonically dispersed in deionized water for 1 hour. Then, it was sprayed onto the surface of the anti-flashover coating and air-dried naturally to obtain glass-based / anti-flashover coating / dirt with a dirt density of 1 mg / cm³. 2 ;

[0043] (4) A 5nm gold film is sputtered onto the dirty surface of the glass plate / anti-flash coating / dirt as a reflective layer for infrared incident light and a plasma enhancer to obtain the glass plate / anti-flash coating / dirt / gold film.

[0044] (5) Place the glass plate / anti-flashover coating / dirt / gold film into the ATR-FTIR sample chamber of the Shimadzu FTIR-8400S infrared spectrometer, with the metal film in close contact with the underside of the ATR-FTIR detector;

[0045] (6) At 25℃ and RH=60%, the glass plate / anti-flashover coating / dirt / gold film were aged for 24h, and then ATR-FTIR was used to test the FTIR of the dirt during the aging process of the anti-flashover coating in situ.

[0046] (7) Analyze the obtained FTIR to identify the organic components that have migrated into the filth.

[0047] Based on FTIR, the characteristic functional groups shown in the table below were identified:

[0048]

[0049] The table above shows that the small molecule indicator methyl fluorosilicone oil has a strong signal and is the main component that migrates into the coating contaminant.

[0050] Example 2:

[0051] A method for in-situ infrared spectroscopy testing of organic matter in dirt on anti-flashover coatings includes the following steps:

[0052] (1) PDMS organosilicon anti-flashover coating was prepared using 5000 mPa·s hydroxyl-terminated polydimethylsiloxane (PDMS) as raw rubber, methyltriacetone oxime silane, dibutyltin dilaurate as catalyst, and 800 mPa·s vinyl silicone oil as small molecule indicator.

[0053] (2) The above coating is applied to a 5mm thick quartz glass plate to obtain a 0.4mm thick anti-flashover coating. The coating is cured at 25℃ for 24 hours and then dried to obtain a glass plate / anti-flashover coating.

[0054] (3) Commercial diatomaceous earth and sodium chloride were added to a ball mill at a ratio of 15:1 and milled for 4 hours. The mixture was then passed through a 200-sieve. The sieved material was ultrasonically dispersed in ethanol for 1 hour, and then sprayed onto the surface of the anti-flashover coating. The mixture was then air-dried to obtain a glass-based / anti-flashover coating / dirt with a dirt density of 1.5 mg / cm³. 2 ;

[0055] (4) A 6nm silver film is deposited on the dirty surface of the glass plate / anti-flashover coating / dirt as a reflective layer for infrared incident light and a plasma enhancer to obtain the glass plate / anti-flashover coating / dirt / silver film.

[0056] (5) Place the glass plate / anti-flashover coating / dirt / silver film into the sample chamber of the Bruker ALPHA infrared spectrometer ATR-FTIR, with the silver film in close contact with the underside of the ATR-FTIR detector;

[0057] (6) At 25℃ and RH=60%, the glass plate / anti-flashover coating / dirt / silver film were aged for 36h, and then ATR-FTIR was used to test the FTIR of the dirt during the aging process of the anti-flashover coating in situ.

[0058] (7) Analyze the obtained FTIR to identify the organic components that have migrated into the filth.

[0059] Based on FTIR, the characteristic functional groups shown in the table below were identified:

[0060]

[0061] The table shows that the small molecule indicator vinyl silicone oil has a strong signal and is the main component that migrates into the coating contaminant.

[0062] Example 3:

[0063] A method for in-situ infrared spectroscopy testing the hydrophobic migration properties of anti-flashover coatings includes the following steps:

[0064] (1) Using the above method, six identical glass plates / anti-flashover coatings / fouling / gold films were prepared, numbered #1, #2, #3, #4, #5, and #6; wherein, the anti-flashover coating was a single-component PDMS silicone rubber with a thickness h = 0.3 mm and a dirt density f = 1 mg / cm³. 2 The small molecule indicator is methyl fluorosilicone oil with a strength of 600 mPa·s.

[0065] (2) Every 1 hour, the FTIR of glass plates #1, #2, and #3 / anti-flashover coating / dirt / gold film was tested using the above method. The integral area corresponding to the first characteristic peak of the small molecule indicator was identified from the results. The average of the three values ​​was recorded as S′. i To remove the coating background S b The influence of S i =S′ i -S b S b =S1; (i represents the i-th).

[0066] (3) Similarly, every 1 hour, the contact angles of glass plates #4, #5, and #6 / anti-flashover coating / dirt / metal film were tested using the traditional method (GB / T19519-2014). The average of the three was recorded as θ. i ;(i represents the ihth).

[0067] (4) Until the 24th hour, S i θ i Everything has stabilized.

[0068] (5) Summary and tabulation:

[0069]

[0070] Plot the curve θ i -i、S i -i, calculate the slope k of each of the three curves. θ =3.2, k s =1.19, i.e., hydrophobic migration rate; find their respective inflection points θc =115.2, S c =7.61, which is the characteristic hydrophobic angle. Calculate the hydrophobic migration rate correction factor: k′=k θ / k s =2.69, characteristic hydrophobic angle correction factor: θ′=θ c / S c =15.14.

[0071] (6) Fix the small molecule indicator and test the effect of coating thickness h on hydrophobic migration rate.

[0072] Take coating thickness h = 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, repeat steps (1)-(5), and measure S. i -i, to obtain k s S c and its correction value k θ =k′k s θ c =θ′S c The results are as follows:

[0073]

[0074] The above results indicate that: 1. The in-situ infrared spectroscopy method of this invention can be used to test the hydrophobic migration of coatings of different thicknesses at a relatively fast speed; 2. The coating thickness has little effect on the characteristic hydrophobic angle, but has a greater effect on the hydrophobic migration rate. The thinner the coating, the faster the migration rate, but there is no linear relationship.

[0075] (7) Fix small molecule indicators and test the effect of dirt density f on hydrophobic migration rate.

[0076] The soil density was set to f = 0.5, 1.0, 1.5, 2.0, and 2.5 mg / cm³. 2 Repeat steps (1)-(5) to measure S. i -i, to obtain k s S c and its correction value k θ =k′k s θ c =θ′S c The results are as follows:

[0077]

[0078] The above results indicate that dirt density affects both the hydrophobic migration rate and the characteristic hydrophobic angle. Higher dirt density results in a lower hydrophobic migration rate and a smaller characteristic hydrophobic angle. Comparatively, its effect is less significant than that of the coating.

[0079] Example 4:

[0080] A method for in-situ infrared spectroscopy testing the hydrophobic migration properties of anti-flashover coatings includes the following steps:

[0081] (1) Using the above method, six identical glass plates / anti-flashover coatings / fouling / gold films were prepared, numbered #1, #2, #3, #4, #5, and #6; wherein, the anti-flashover coating was a single-component PDMS silicone rubber with a thickness h = 0.4 mm and a dirt density f = 1.5 mg / cm³. 2 The small molecule indicator is 800mPa vinyl silicone oil.

[0082] (2) Every 1 hour, the FTIR of glass plates #1, #2, and #3 / anti-flashover coating / dirt / silver film was tested using the above method. The integral area corresponding to the first characteristic peak of the small molecule indicator was identified from the results. The average of the three values ​​was recorded as S′. i To remove the coating background S b The influence of S i =S′ i -S b S b =S1; (i represents the i-th digit)

[0083] (3) Similarly, every 1 hour, the contact angles of glass plates #4, #5, and #6 / anti-flashover coating / dirt / metal film were tested using the traditional method (GB / T19519-2014). The average of the three was recorded as θ. i (i represents the i-th digit)

[0084] (4) Until the 36th hour, S i θ i Everything has stabilized.

[0085] (5) Summary and tabulation:

[0086]

[0087] Plot the curve θ i -i、S i -i, calculate the slope k of each of the three curves. θ =2.5, k s =1.5, i.e., hydrophobic migration rate; find their respective inflection points θ c =106.5, S c =6.72, which is the characteristic hydrophobic angle. Calculate the hydrophobic migration rate correction factor: k′=k θ / k s =1.67, characteristic hydrophobic angle correction factor: θ′=θ c / S c =15.85.

[0088] (6) Fix the small molecule indicator and test the effect of coating thickness h on hydrophobic migration rate.

[0089] Take coating thickness h = 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, repeat steps (1)-(5), and measure S. i -i, to obtain k s S c and its correction value k θ =k′k s θ c =θ′S c The results are as follows:

[0090]

[0091] The above results confirm that the coating thickness has little effect on the characteristic hydrophobic angle, but a significant effect on the hydrophobic migration rate. The thinner the coating, the faster the migration rate, but there is no linear relationship.

[0092] (7) Fix small molecule indicators and test the effect of dirt density f on hydrophobic migration rate.

[0093] The soil density was set to f = 0.5, 1.0, 1.5, 2.0, and 2.5 mg / cm³. 2 Repeat steps (1)-(5) to measure S. i -i, to obtain k s S c and its correction value k θ =k′k s θ c =θ′S c The results are as follows:

[0094]

[0095] The above results confirm that dirt density affects both the hydrophobic migration rate and the characteristic hydrophobic angle. Higher dirt density results in a lower hydrophobic migration rate and a smaller characteristic hydrophobic angle. Comparatively, its effect is less significant than that of the coating.

Claims

1. A method for in-situ infrared spectroscopy testing of organic matter in dirt from anti-flashover coatings, characterized in that, Includes the following steps: (1) Prepare an anti-flashover coating and incorporate a small molecule indicator into it; (2) Apply the anti-flashover coating to the glass plate to obtain an anti-flashover coating with a thickness of 0.3~0.5mm. After curing and drying, the glass plate / anti-flashover coating is obtained. (3) For the pretreatment of dirt, pass it through a 200-sieve, and disperse the sieve material evenly in deionized water or ethanol. Then spray it onto the surface of the anti-flashover coating. After it is fully dried, you will get glass plate / anti-flashover coating / dirt. (4) On the dirty surface of glass plate / anti-flashover coating / dirt, a metal film is deposited as a reflective layer for infrared incident light and a plasma enhancer to obtain glass plate / anti-flashover coating / dirt / metal film. (5) Place the glass plate / anti-flashover coating / dirt / metal film into the sample chamber of the attenuated total reflection Fourier transform infrared spectrometer, with the metal film in close contact with the detector of the ATR-FTIR; (6) Set the ambient temperature and humidity, age the glass plate / anti-flashover coating / dirt / metal film for a certain period of time, and then use ATR-FTIR to test the FTIR of dirt during the aging process of the anti-flashover coating in situ; (7) Analyze the obtained FTIR to identify the organic components that have migrated into the filth.

2. The method for in-situ infrared spectroscopy testing of organic matter in anti-flashover coatings according to claim 1, characterized in that, The aforementioned anti-flashover coating refers to silicone coating or fluorine coating.

3. The method for in-situ infrared spectroscopy testing of organic matter in anti-flashover coatings according to claim 1, characterized in that, The small molecule indicator refers to an indicator molecule that is compatible with the anti-flashover coating and diffuses onto the surface of the anti-flashover coating, with a molecular weight <10000g / mol and a viscosity <1000mPa.s.

4. The method for in-situ infrared spectroscopy testing of organic matter in anti-flashover coatings according to claim 1, characterized in that, The aforementioned contamination refers to simulated contamination or contamination of the insulator coating in a power system, with a coating amount of 0~3 mg / cm³. 2 .

5. The method for in-situ infrared spectroscopy testing of organic matter in anti-flashover coatings according to claim 1, characterized in that, The simulated filth refers to diatomaceous earth, sodium chloride, or a mixture of the two.

6. The method for in-situ infrared spectroscopy testing of organic matter in anti-flashover coatings according to claim 1, characterized in that, The metal thin film refers to a nanoparticle thin film of platinum, gold, silver, or copper, with a thickness of 6-10 nm.

7. A method for in-situ infrared spectroscopy testing the hydrophobic migration properties of anti-flashover coatings, characterized in that, Includes the following steps: (1) Prepare anti-flashover coating and add small molecule indicator to it; apply the anti-flashover coating to a glass plate to obtain an anti-flashover coating with a thickness of 0.3~0.5 mm, cure and dry to obtain glass plate / anti-flashover coating; For pretreatment of the contaminant, the material is passed through a 200-sieve, and the sieved material is uniformly dispersed in deionized water or ethanol. Then, it is sprayed onto the surface of the anti-flashover coating. After thorough drying, a glass plate / anti-flashover coating / contaminant is obtained. A metal film is deposited on the surface of the contaminant of the glass plate / anti-flashover coating / contaminant as a reflective layer for infrared incident light and a plasma enhancer, resulting in a glass plate / anti-flashover coating / contaminant / metal film. Six identical glass plates / anti-flashover coating / contaminant / metal film are prepared by cutting, and are numbered #1, #2, #3, #4, #5, and #6. (2) Every 1 hour, test the FTIR of glass plates #1, #2, and #3 / anti-flashover coating / dirt / metal film, and identify the integrated area corresponding to the first characteristic peak of the small molecule indicator. The average of the three is recorded as follows: In order to remove the coating background The impact, = - , = ; i Indicates the first i h; (3) Similarly, at 1-hour intervals, the contact angles of glass plates #4, #5, and #6 / anti-flashover coating / dirt / metal film were tested using the GB / T19519-2014 method. The average of the three was recorded as follows: ; i Indicates the first i h; (4) Until the Nth h, When all values ​​tend to stabilize, Nh is called the characteristic time of the hydrophobic migration property of the anti-flashover coating. (5) Summary and tabulation: Draw curves - i , - i Calculate the slopes of the two curves. , That is, the hydrophobic migration rate; find their respective inflection points. , That is, the characteristic hydrophobic angle; definition: Hydrophobic migration rate correction factor: / ; Characteristic hydrophobicity angle correction factor: / ; (6) Fix the small molecule indicator and test the coating thickness. h Effect on hydrophobic migration rate; Change coating thickness h， Repeat steps (1) through (5) to measure. - i Seeking , and its correction value , ; (7) Fix small molecule indicators and test dirt density. f Effect on hydrophobic migration rate; Change the density of filth f， Repeat steps (1) through (5) to measure. - i Seeking , and its correction value , .

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