Recyclable electric sensing coating for defect detection and preparation method thereof

Abstract

The invention discloses a preparation method of a recyclable electric sensing coating for defect detection. The preparation method is characterized by comprising the following steps: S1, preparing an electroluminescent unit EL; s2, preparing field coupling microspheres FCM based on an electroluminescent unit EL; and S3, preparing the recoverable electric sensing coating based on the field coupling microsphere FCM. The method has the advantages that electric field sensing and an environmental protection concept are successfully combined, and a low-cost, high-sensitivity and lossless polymer interface defect detection method is created. By visualizing the distribution of the electric field around the defect, the REC not only solves the bottleneck of the traditional technology in the aspects of detection precision, economy and environmental protection (recycling), but also provides a new way for realizing the fine management and maintenance of the material state, and has far-reaching significance for promoting the stable operation in the fields of electrical equipment and electronic equipment.

Description

Technical Field

[0001] This invention belongs to the field of electrical engineering, specifically a recyclable electrosensitive coating for defect detection. Background Technology

[0002] Polymer materials play a central role in modern electrical and electronic equipment, and their performance stability and reliability directly affect the safe operation of the entire system. When dielectric polymers operate in high electric field environments, stress concentration at the interface becomes particularly prominent, making interface defects a key factor affecting material performance and lifespan. Non-uniform electric field distribution, especially in defective areas, accelerates the material degradation process, thereby shortening the service life of electrical equipment. Therefore, developing effective detection technologies, especially methods capable of real-time and accurate identification and location of these interface defects, is of great significance for maintaining safe equipment operation and extending its service life.

[0003] In existing technologies, various non-destructive testing (NDT) methods exist, each with its specific application scenarios and limitations. High-frequency eddy current testing (HFEC) is suitable for defect detection in metallic conductors, while magnetic particle testing (MPI) is primarily applied to ferromagnetic materials. Ultrasonic testing (UT) and microwave imaging (MI), although applicable to polymer materials, are limited by their low spatial resolution, making it difficult to accurately identify minute defects. X-ray computed tomography (XCT), while providing high-precision images, may cause physical damage to the sample during the testing process. Terahertz (THz) characterization techniques, with their high precision and non-contact characteristics, show great potential in the field of NDT, but their high cost and operational complexity limit their widespread application. The main technical drawbacks of existing technologies for detecting defects at dielectric polymer interfaces can be summarized as follows:

[0004] 1. Detection Limitations: High-frequency eddy current (HFEC) and magnetic particle inspection (MPI) technologies are limited to conductive and ferromagnetic materials and cannot be effectively applied to defect detection in dielectric polymers because these materials lack the necessary electromagnetic induction properties. This limitation restricts the application of these technologies in electrical equipment where dielectric polymers are widely used.

[0005] 2. Insufficient resolution: Although ultrasonic testing (UT) and microwave imaging (MI) technologies can be used for polymer inspection, their low spatial resolution makes them inadequate for detecting minute defects at the millimeter level and below, which directly affects the accuracy and practicality of the inspection.

[0006] 3. Potential damage risk: Although X-ray computed tomography (XCT) provides high-precision imaging, the vacuum stress and high-temperature radiation introduced during the inspection process may cause additional damage to the material being tested.

[0007] 4. Cost and efficiency issues: Although terahertz (THz) characterization technology has high precision, it relies on expensive equipment and complex operating procedures, which not only increases economic costs but also prolongs detection time and reduces overall efficiency.

[0008] 5. Innovation Advantages: The applicant previously submitted two invention patents to the State Intellectual Property Office: "CN117929949A A Micro Sensor and Its Preparation Method" and "CN117924883A A Self-Detection Dielectric Composite Material and Its Preparation Method." These two applications are more theoretically focused, requiring the integration of a micro sensor and a dielectric composite material to achieve defect detection functionality. The process is complex, costly, and non-recyclable. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention proposes a recyclable electrosensitive coating for defect detection, thereby achieving the following objective:

[0010] 1. Breakthrough in detection limitations: By designing recyclable electrosensitive coating (REC), the problem of difficult effective detection of interface defects in dielectric polymers is innovatively solved, filling the gap in the field of dielectric material detection technology.

[0011] 2. Improved detection accuracy: By utilizing the fluorescence indication characteristics of field-coupled microspheres (FCM) inside the REC under a distorted electric field, the precise location of defects is achieved, which significantly improves the resolution and accuracy of detection, especially for micro-defects.

[0012] 3. Ensuring non-destructive and environmentally friendly operation: REC's infrared phase transition characteristics enable it to complete the test without damaging the material being tested. Furthermore, its recycling mechanism embodies the concept of environmental protection, reducing material consumption and environmental burden during the testing process.

[0013] 4. Optimize cost-effectiveness: By providing a low-cost, efficient and highly sensitive detection method, it overcomes the shortcomings of traditional technologies in terms of cost control and detection efficiency, opening up a new economical and feasible path for non-destructive testing of dielectric polymers.

[0014] To achieve the above objectives, the present invention adopts the following technical solution:

[0015] A method for preparing a recyclable electrosensitive coating for defect detection, comprising the following steps:

[0016] S1. Fabrication of electroluminescent (EL) units;

[0017] S2. Fabrication of field-coupled microspheres (FCM) based on electroluminescent (EL) units;

[0018] S3. Preparation of recyclable electrosensing coating based on field-coupled microspheres FCM.

[0019] Preferably, step S1 specifically includes:

[0020] S2-1. Mix 20 parts by mass of ZnS with 0.5 parts by mass of CuCl2; grind the mixture with methanol until...

[0021] Continue until the mixture is completely dry;

[0022] S2-2, Sinter the mixture;

[0023] S2-3. Anneal the sintered product and cool it to room temperature;

[0024] S2-4. The cooled mixture is washed, dried, and sieved for purification to obtain uniform ZnS:Cu particles;

[0025] S2-5. Place ZnS:Cu particles into a microfluidic bed and suspend them under argon gas; inject a solution containing 10 wt% trimethylolpropionate.

[0026] The aluminum was reacted with argon gas for 10 minutes;

[0027] S2-6. Replace the argon gas containing 10wt% trimethylaluminum with oxygen containing 10wt% ozone and continue the reaction for 30 minutes.

[0028] S2-7. After cooling, an electroluminescent unit (EL) is obtained.

[0029] Preferably, in S2-1, the mass fraction of methanol is 7.

[0030] Preferably, in S2-2, the mixture is loaded into an alumina crucible, and the alumina crucible is transferred to a tube furnace for sintering under argon at 1000°C for 2 hours.

[0031] Preferably, in S2-3, the sintered product is transferred to a muffle furnace and annealed at 300°C for 1 hour.

[0032] Preferably, step S2 specifically comprises:

[0033] S2-1. Add 200 parts by mass of deionized water and 5 parts by mass of GA to a three-necked flask and stir to obtain an aqueous phase.

[0034] S2-2, 10 parts by mass of E51 epoxy resin prepolymer, 1 part by mass of PI-369, 2 parts by mass of TMPTA, 1 part by mass of nano-barium titanate and 2 parts by mass of electroluminescent unit EL are ultrasonically mixed and dispersed to obtain an organic phase.

[0035] S2-3. Place the aqueous phase in a water bath at 80°C, then gradually introduce the organic phase into the aqueous phase while stirring at 500 rpm for 20 minutes; reduce the stirring speed to 250 rpm and place the emulsion under ultraviolet light for 10 minutes.

[0036] S2-4. After washing, drying and sieving, uniform field-coupled microspheres (FCM) are obtained.

[0037] Preferably, the ultraviolet light is 395nm ultraviolet light.

[0038] Preferably, step S3 specifically comprises:

[0039] S3-1. Mix 30 parts by weight of paraffin liquid and 2 parts by weight of polystyrene block-polybutadiene block-polystyrene in a vacuum chamber at 100°C for 20 hours.

[0040] S3-2. Place the mixture in a freeze dryer at -20°C for 10 hours to obtain the matrix material;

[0041] S3-3. The matrix material and field-coupled microspheres (FCM) are mixed at a mass ratio of 9:1 under vacuum at 100°C.

[0042] S3-4. Cool to room temperature to obtain recyclable electrosensing coating.

[0043] The present invention also discloses a recyclable electroluminescent coating for defect detection. The microstructure of the recyclable electroluminescent coating includes an external electroluminescent unit EL and an internal dielectric core. The electroluminescent unit EL is composed of an Al2O3 shell and a ZnS:Cu core.

[0044] Preferably, the average diameter of the electroluminescent unit EL is 19.6 μm.

[0045] Beneficial effects of the present invention

[0046] The advantage of this invention lies in its successful combination of electric field sensing and environmental protection concepts, creating a low-cost, highly sensitive, and non-destructive method for detecting polymer interface defects. By visualizing the electric field distribution around the defects, REC not only overcomes the bottlenecks of traditional technologies in terms of detection accuracy, economy, and environmental friendliness (recyclability), but also provides a new approach for achieving precise management and maintenance of material conditions, which has profound significance for promoting the stable operation of electrical and electronic equipment. Specifically:

[0047] 1. The recyclable electrosensing coating (REC) proposed in this invention provides an innovative solution. Through its unique design, REC can accurately locate interface defects without damaging the material, primarily thanks to its internal field-coupled microspheres (FCM). These microspheres emit fluorescence under the influence of a distorted electric field, forming an intuitive indication system, thus overcoming the shortcomings of traditional methods in terms of resolution, cost, or potential damage to materials. This design not only significantly improves the accuracy and efficiency of detection but also significantly reduces detection costs because REC is recyclable, meaning it can be reused without frequent replacement, conforming to economic and environmental principles.

[0048] 2. This invention enhances the sensitivity to distorted electric fields by optimizing the FCM structure and employing a nested design. This improvement not only increases the sensitivity of defect detection but also enables the REC to exhibit different luminescence characteristics based on different types of interface defects, making rapid defect identification and classification possible. This is extremely important in practical applications because it allows for a more comprehensive and in-depth assessment of the polymer material's condition, helping to take timely measures to prevent material degradation and extend the service life of electrical equipment. Attached Figure Description

[0049] Figure 1 This is a particle size distribution diagram of the EL unit in the embodiment.

[0050] Figure 2 The particle size distribution diagram of FCM in the example is shown.

[0051] Figure 3 The diagram shows the TG and DTG curves of FCM in the example.

[0052] Figure 4 The viscosity curve of REC in the example is shown.

[0053] Figure 5 The infrared spectra of the matrix material at different temperatures are shown in the examples.

[0054] Figure 6 The graphs shown are TG and DTG curves of the matrix material in the examples.

[0055] Figure 7 The TG and DTG curves of REC are shown in the example.

[0056] Figure 8 The image shows the electroluminescence spectrum of REC in the example.

[0057] Figure 9 The image shows the transmittance curve of the matrix material in the embodiment.

[0058] Figure 10The diagram shows the cyclic electroluminescence characteristics in the embodiment.

[0059] Figure 11 This is a schematic diagram of REC defect detection in the embodiment. Detailed Implementation

[0060] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto:

[0061] Materials: Zinc sulfide (ZnS), methanol (CH3OH), deionized water (H2O), trimethylolpropane triacrylate (TMPTA), copper chloride (CuCl2), 2-benzyl-2-(dimethylamino)-4'-morpholinophenyl ethyl ketone (PI-369), trimethylaluminum solution (1.0M hexane solution), nano-sized barium titanate (BaTiO3), gum arabic (GA, medical grade), E51 epoxy resin prepolymer, paraffin wax, polystyrene block-polybutadiene block-polystyrene, ozone (O3), oxygen (O2), and argon (Ar). Ozone (O3), oxygen (O2), and argon (Ar) were purchased from Chongqing Ruixin Gas Co., Ltd., and the rest were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0062] Preparation of the electroluminescent (EL) unit: First, 20 g of ZnS and 0.5 g of CuCl2 were transferred to an agate mortar and mixed. The mixture was then ground with methanol for 3 hours (in the preferred embodiment, the mass ratio of the mixture to methanol was 3:1) until the precursor mixture was completely dry. The mixture was then placed in an alumina crucible, transferred to a tube furnace, and sintered at 1000 °C under argon for 2 hours. Subsequently, the sintered product was transferred to a muffle furnace and annealed at 300 °C for 1 hour, then cooled to room temperature. The mixture was purified by washing, drying, and sieving to form uniform ZnS:Cu particles. The ZnS:Cu particles were placed in a microfluidic bed and suspended under argon. Then, argon containing 10 wt% trimethylaluminum was injected into the reaction chamber at 200 °C for 10 minutes. The injected gas was replaced with oxygen containing 10 wt% ozone to promote the growth of an amorphous alumina film on the surface of the ZnS:Cu particles. Finally, the EL unit is obtained after a cooling period (20 minutes in the preferred embodiment).

[0063] Preparation of field-coupled microspheres (FCM): Initially, 200 mL of deionized water and 5 g of GA were added to a three-necked flask and mechanically stirred at 400 rpm for 1 hour to obtain an aqueous phase. Then, 10 g of E51 epoxy resin prepolymer, 1 g of PI-369, 2 g of TMPTA, 1 g of nano-barium titanate, and 2 g of EL units were added to a beaker and ultrasonically mixed and dispersed for 2 hours to obtain an organic phase. The aqueous phase was placed in a water bath at 80 °C, and then the organic phase was gradually introduced into the aqueous phase, followed by stirring at 500 rpm for 20 minutes. Subsequently, the stirring speed was reduced to 250 rpm, and the emulsion was placed under ultraviolet light (395 nm) for 10 minutes. Finally, after washing, drying, and sieving, a uniform FCM was obtained.

[0064] Preparation of Recyclable Electrosensitive Coating (REC): First, 30g of paraffin wax and 2g of polystyrene block-polybutadiene block-polystyrene were mixed in a vacuum chamber at 100°C for 20h. Then, the mixture was placed in a freeze-drying cabinet at -20°C for 10h to obtain the matrix material. Finally, the matrix material was mixed with FCM at 100°C under vacuum (preferably, the mass ratio of matrix material to FCM is 9:1), followed by further cooling to obtain REC.

[0065] Characterization of FCM: The microstructure of FCM consists of an outer electroluminescent (EL) unit and an inner dielectric (DE) core. The EL unit is composed of an Al₂O₃ shell and a ZnS:Cu core. The Al₂O₃ shell provides moisture protection and extends the luminescence lifetime of ZnS:Cu. The average diameter of the EL unit is approximately 19.6 μm, with most particles falling within the 15-27 μm range. Figure 1 ).

[0066] The average diameter of FCM is approximately 162.3 μm, with most particles ranging in size from 125 to 200 μm. Figure 2 ).

[0067] The thermogravimetric (TG) and thermogravimetric (DTG) curves of the FCM indicate that the organic components in the FCM underwent thermal decomposition within a temperature range of 294.3℃–524.6℃. Figure 3 This confirms the thermal stability of FCM.

[0068] Characterization of REC: REC consists of FCM and a matrix material with infrared phase change properties, allowing it to transform into a fluid under infrared radiation and separate from the polymer interface, thus achieving environmentally friendly recycling. To study the phase change process of REC, a rheometer was used to measure the viscosity change during melting. When the temperature reached 66.2℃, REC underwent a transition from a solid to a high-viscosity fluid. Figure 4As temperature increases, viscosity shows a continuous decreasing trend. At temperatures exceeding 80.1℃, the viscosity drops to 10. 4 mPa·s indicates that REC has transformed into a low-viscosity fluid.

[0069] Infrared spectroscopy was used to characterize the microscopic changes in REC during melting. At temperatures of 40°C, 60°C, 80°C, and 100°C, the matrix material at 2920.4 cm⁻¹... -1 2851.9cm -1 1457.8cm -1 1376.6cm -1 and 720.9cm -1 It exhibits a stable absorption peak at ( ) Figure 5 ). 2920.4cm -1 It represents the asymmetric tensile vibration of CH2, 2851.9 cm. -1 It is a symmetrical tensile vibration of CH2, 1457.8 cm. -1 It is an asymmetric bending vibration of CH3, 1376.6 cm. -1 It is a symmetrical bending vibration of CH3, 720.9 cm. -1 This is an in-plane rocking vibration of CH2. As the temperature increases, the molecular chains slide between the chains, thereby loosening the CC backbone and promoting radiation absorption at the corresponding wavelength. This leads to a gradual increase in the absorption peak in the backbone region.

[0070] Thermogravimetric analysis (TGA) was performed on the matrix material and REC to investigate their thermal stability. The TG and DTG curves of the matrix material showed that the decomposition range of the oligomers was 138.8℃ to 389.3℃, and that of the polymers was 389.3℃ to 476.1℃. Figure 6 In the REC TG and DTG curves, the peak at 329.5℃ is caused by the decomposition of oligomers in the matrix material, accounting for approximately 84.6%. Figure 7 The peak at 452.9℃ is generated by the decomposition of the matrix material and polymers in the FCM, accounting for approximately 11.1%. Finally, the residual material is inorganic matter from the FCM, accounting for approximately 4.3%. Therefore, REC does not undergo thermal decomposition below 130℃, thus confirming its thermal stability under normal operating conditions.

[0071] REC exhibits electrosensitivity because the valence electrons of the EL unit are excited under electrical excitation and complex with Cu holes, releasing 2.45 eV of energy and producing cyan fluorescence. To measure the fluorescence spectrum, a multilayer sample composed of quartz glass, indium tin oxide (ITO), and REC was prepared. The emission spectrum was measured using a steady-state / lifetime fluorescence spectrometer under a uniform electric field of 1.5 kV / mm. The fluorescence spectrum of REC approximately follows a normal distribution, with a peak at 506.1 nm and a primary spectral range of 437.6 nm to 585.3 nm. Figure 8 ).

[0072] The transmittance of the matrix material was measured using a UV-Vis-NIR spectrophotometer. The transmittance of the primary spectrum ranged from 90.33% to 91.37%. Figure 9 This indicates that it has excellent fluorescence transmittance characteristics.

[0073] To investigate the cyclic detection reliability of REC, a series of tests were conducted under excitation at an electric field of 1.5 kV / mm to evaluate the photon count at a wavelength of 506.1 nm at different cycle times. A set of REC samples underwent 100 cycles. The results showed that the average photon count decreased slightly, with the change remaining within approximately 1.4% of the initial value. Figure 10 This verifies the reliability of the cyclic detection.

[0074] Defect detection performance of REC: In a spatial electric field, the distorted electric field caused by defects drives REC to produce in-situ distorted electroluminescence, representing defect indication information. To study the defect detection performance of REC, a series of photolithographic defects of different sizes were created to evaluate the defect detection accuracy of REC. Figure 11 As the defect size decreases, the intensity of electroluminescence also decreases. Defect (5) remains surrounded by the weakest fluorescence, while defect (6) shows no fluorescence. The results indicate that the size of defect (6) is too small to induce a significant distorted electric field. The effective length of defect (5) is approximately 200 μm, indicating that the defect detection accuracy of REC is less than 200 μm.

[0075] The present invention provides an electrosensing coating with recyclable function, which can be directly applied to existing dielectric materials for defect detection. It is not only convenient to operate, but also recyclable, and has economic and environmentally friendly properties.

[0076] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for preparing a recyclable electrosensitive coating for defect detection, characterized in that... It includes the following steps: S1. Fabrication of electroluminescent (EL) units; S2. Fabrication of field-coupled microspheres (FCM) based on electroluminescent (EL) units; S3. Preparation of recyclable electrosensing coating based on field-coupled microspheres FCM.

2. The method according to claim 1, characterized in that... Step S1 specifically involves: S2-1. Mix 20 parts by mass of ZnS with 0.5 parts by mass of CuCl2; grind the mixture with methanol until the mixture is completely dry; S2-2, Sinter the mixture; S2-3. Anneal the sintered product and cool it to room temperature; S2-4. The cooled mixture is washed, dried, and sieved for purification to obtain uniform ZnS:Cu particles; S2-5. Place ZnS:Cu particles into a microfluidic bed and suspend them under argon gas; inject argon gas containing 10wt% trimethylaluminum and react for 10 minutes. S2-6. Replace the argon gas containing 10wt% trimethylaluminum with oxygen containing 10wt% ozone and continue the reaction for 30 minutes. S2-7. After cooling, an electroluminescent unit (EL) is obtained.

3. The method according to claim 2, characterized in that... In S2-1, the mass fraction of methanol is 7.

4. The method according to claim 2, characterized in that... In S2-2, the mixture is loaded into an alumina crucible, which is then transferred to a tube furnace for sintering at 1000°C under argon atmosphere for 2 hours.

5. The method according to claim 2, characterized in that... In S2-3, the sintered product is transferred to a muffle furnace and annealed at 300°C for 1 hour.

6. The method according to claim 1, characterized in that... Step S2 specifically involves: S2-1. Add 200 parts by mass of deionized water and 5 parts by mass of GA to a three-necked flask and stir to obtain an aqueous phase. S2-2, 10 parts by mass of E51 epoxy resin prepolymer, 1 part by mass of PI-369, 2 parts by mass of TMPTA, 1 part by mass of nano-barium titanate and 2 parts by mass of electroluminescent unit EL are ultrasonically mixed and dispersed to obtain an organic phase. S2-3. Place the aqueous phase in a water bath at 80°C, then gradually introduce the organic phase into the aqueous phase while stirring at 500 rpm for 20 minutes; reduce the stirring speed to 250 rpm and place the emulsion under ultraviolet light for 10 minutes. S2-4. After washing, drying and sieving, uniform field-coupled microspheres (FCM) are obtained.

7. The method according to claim 6, characterized in that... The ultraviolet light is 395nm ultraviolet light.

8. The method according to claim 1, characterized in that... Step S3 specifically involves: S3-1. Mix 30 parts by weight of paraffin liquid and 2 parts by weight of polystyrene block-polybutadiene block-polystyrene in a vacuum chamber at 100°C for 20 hours. S3-2. Place the mixture in a freeze dryer at -20°C for 10 hours to obtain the matrix material; S3-3. The matrix material and field-coupled microspheres (FCM) are mixed at a mass ratio of 9:1 under vacuum at 100°C. S3-4. Cool to room temperature to obtain recyclable electrosensing coating.

9. A recyclable electrosensitive coating for defect detection, characterized in that... The microstructure of the recyclable electrosensitive coating includes an external electroluminescent unit EL and an internal dielectric core. The electroluminescent unit EL is composed of an Al2O3 shell and a ZnS:Cu core.

10. The recyclable electrosensing coating according to claim 1, characterized in that... The average diameter of the electroluminescent unit (EL) is 19.6 μm.

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