Treatment method for improving thermal cycle cracking of electric heating anti-icing device

Abstract

The invention discloses a treatment method for improving thermal cycle cracking of an electric heating anti-icing device. Belongs to the technical field of surface treatment. Thermoplastic polyurethane is prepared on a metal substrate as a matrix, aminated carbon fibers are directionally arranged in the matrix to form a conductive enhancement layer, a heat stabilizer and an anti-hydrolysis agent are added into the conductive enhancement layer, and a hydrophobic layer is arranged on the surface of the conductive enhancement layer. Based on an electrostatic spinning technology and a carbon fiber modified conductive fiber network structure, through material-structure-function collaborative design and through electrostatic spinning electric field force driving, electrostatic spinning parameters are optimized, fiber directional arrangement is achieved, meanwhile, aminated carbon fibers are arranged in a polyurethane matrix, the interface bonding force is improved, and the resistivity is effectively reduced; and good heating power density under low working voltage is realized.

Description

Technical Field

[0001] The present invention relates to a method for improving thermal cycle cracking of an electric heating anti-icing device, belonging to the technical field of surface treatment. Background Art

[0002] The main shortcomings of the existing technology include: in the existing electric heating anti-icing technology, there are technical difficulties such as poor interface bonding between the copper sheet (i.e., the metal base of the electric heating anti-icing device) and the resin matrix, easy cracking during thermal cycling, and a sharp increase in interface thermal resistance with increasing thermal cycle times. The reason is that the thermal expansion coefficients between the copper sheet and the resin matrix are very different. During repeated heating / cooling cycles, stress concentration occurs at the interface, causing microcracks to initiate and expand, and eventually causing the copper sheet to peel off from the matrix; after thermal cycling, the traditional copper sheet-resin interface has an increase in microcracks and pores, resulting in a significant increase in interface thermal resistance, reducing heat transfer efficiency and increasing de-icing energy consumption; the randomly dispersed carbon-based conductive network forms a highly tortuous path due to the disordered arrangement of fibers, resulting in high resistivity; in addition, the aging problem of the polymer matrix in a humid and hot / ultraviolet environment causes rapid performance degradation, making the surface structure of the electric heating anti-icing device insufficiently durable.

[0003] This invention addresses these issues through innovative design. It uses electrospinning technology to align amino-modified carbon fibers within a polyurethane matrix, reducing resistivity in the heating direction. Hindered amine light stabilizers and anti-hydrolysis agents are also incorporated into the polyurethane matrix to ensure performance stability in wet, hot, and ultraviolet environments. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for improving thermal cycle cracking of an electric heating anti-icing device.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: An electrothermal anti-icing device comprises a copper sheet as the primary heating layer, a thermoplastic polyurethane polymer matrix material formed on the copper sheet, and a conductive reinforcement layer formed by amino-modified carbon fibers arranged in a directional pattern within the polyurethane matrix. The device also incorporates functional additives, including a heat stabilizer (such as the hindered amine light stabilizer Tinuvin 770) and an anti-hydrolysis agent (such as Stabaxol P200). A 30-50 μm thick fluorinated polyurethane hydrophobic layer is also applied to the surface.

[0006] Electrothermal anti-icing devices include aerospace skins, high-speed train pantographs, wind turbine blades, and high-voltage transmission lines.

[0007] A method for improving thermal cycle cracking of an electric heating anti-icing device comprises the following steps: Step 1: The first step is to pre-treat the metal substrate by laser etching. Laser etching is performed on the surface of the copper sheet to form surface microgrooves to increase the specific surface area, making it easier for electrospinning to be embedded in the grooves.

[0008] The copper sheet substrate is laser etched, and its surface has regular circular grooves with a depth of micrometers and a groove diameter of about 45-55μm.

[0009] Step 2: Pre-treat the carbon fibers. Select high-purity carbon fibers (C content ≥ 95%) as the conductive reinforcement phase, with a diameter within the range of 7-10 μm.

[0010] For high-purity carbon fiber, you can choose Zhongfu Shenying SYT45-3K-20U.

[0011] The carbon fiber is placed in a 60%-70% concentrated nitric acid solution and refluxed in a constant temperature water bath at 75-85°C for 3.5-4.5 hours to increase the carboxyl density on the carbon fiber surface and form a groove structure on the carbon fiber surface.

[0012] The main principle for increasing the carboxyl density on the carbon fiber surface is to use concentrated nitric acid to oxidize the carbon fibers, attacking unstable carbon atoms on the carbon fiber surface and converting them into oxygen-containing groups, thereby generating carboxyl oxygen-containing functional groups. The purity of the concentrated nitric acid must be controlled to avoid excessive concentrations, and the temperature of the concentrated nitric acid solution must be kept constant to avoid fluctuations. This ensures that the carbon fibers meet the requirements of subsequent electrospinning.

[0013] Reaction equation:

[0014] The usage ratio of carbon fiber and 60%-70% concentrated nitric acid is usually 0.9g-1.1g carbon fiber corresponding to about 13mL-17mL of 60%-70% concentrated nitric acid.

[0015] Then, amino modification is carried out. The oxidized carbon fiber is immersed in a 4wt%-6wt% silane coupling agent (KH550) ethanol solution (the pH value of the solution is controlled between 9-10, and ammonia water is used for pH adjustment), and placed under nitrogen atmosphere protection. It is heated to 75-85°C for modification reaction, and the reaction time is 5-7 hours.

[0016] To process 1g of oxidized carbon fiber, 20-50mL of a 4wt%-6wt% silane coupling agent (KH550) ethanol solution is usually required. Anhydrous ethanol is preferred.

[0017] Amination modification is the process of using a silane coupling agent to chemically react with the carboxyl groups on the surface of oxidized carbon fibers to form covalently grafted amino functional groups.

[0018] The silane coupling agent hydrolyzes in an ethanol solution to generate silanols, which then undergo a condensation reaction with the carboxyl groups on the carbon fiber surface. The silane coupling agent bonds to the oxidized carbon fibers through silicon-oxygen bonds, ultimately grafting -NH2 functional groups onto the carbon fiber surface, completing the amino modification.

[0019] Then, the carbon fibers were ultrasonically cleaned with deionized water and anhydrous ethanol in sequence, taken out and vacuum dried, and sieved to obtain uniformly dispersed modified carbon fibers.

[0020] Step 3: Thermoplastic polyurethane (BASF Elastollan 1185A) is selected as the polymer matrix, and the ratio of different reactants is amino carbon fiber: 8wt%-8.4wt% (mass fraction), polyurethane matrix: 90.75wt%-91.45wt% (mass fraction), stabilizer about 0.4wt%-0.6wt% and anti-hydrolysis agent about 0.15wt%-0.25wt%.

[0021] The polymer matrix is ​​thermoplastic polyurethane with a hardness range of 80A-95A, which can form a covalent bond with the amino carbon fiber. The reaction mechanism is achieved by chemical reaction between the isocyanate group of the polyurethane and the amino group on the carbon fiber surface. The free -NCO group in the polyurethane can react with the -NH2 of the amino carbon fiber to form a urea bond (-NH-CO-NH-). The main reaction formula is:

[0022] Pre-mixing is performed using a high-speed shear emulsifier at a speed of 9000-11000 rpm for 4-6 minutes. Fine dispersion is then achieved using a three-roll mill with a roller spacing of 48-52 μm. Degassing is performed using a vacuum planetary mixer at a pressure of 0.04-0.06 MPa for 28-32 minutes.

[0023] Step 4: The prepared spinning solution is electrospun at a spinning voltage of 16±0.5kV, a receiving distance of 18±0.5cm, a solution propulsion rate of 1.1mL / h-1.3mL / h, a drum diameter of 195mm-205mm, a rotation speed of 2800rpm-3400rpm, a surface linear velocity of 33.0m / s-34.0m / s, and a temperature of 40±2°C. Multi-level electric field control is employed, with the primary electric field strength at the needle tip ranging from 1.7kV / cm-1.9kV / cm and the secondary electric field receiver biased at 2.8kV-3.2kV.

[0024] The copper sheet obtained in step 1 is fixed on the drum, and the relative position of the copper sheet and the spinneret is adjusted to ensure that the surface deposition of the copper sheet is relatively uniform.

[0025] The length of amino carbon fibers is usually less than 1 mm. The high-speed shearing process can cause them to break further. The directional arrangement is achieved by using a high-voltage electric field to stretch the charged jet along the direction of the electric field lines. The generated fibers are parallel to the direction of the electric field, that is, arranged longitudinally.

[0026] Step 5: Vacuum curing is performed, maintaining a vacuum degree of 0.09MPa-0.11MPa. A step-by-step curing process is employed: the first stage is maintained at 38-42°C for 28-32 minutes to relax the molecular chains; the second stage is maintained at 63-67°C for 115-125 minutes to pre-crosslink; the third stage is maintained at 83-87°C for 350-370 minutes to achieve full curing. The temperature is then lowered at a uniform rate of 1.9-2.1°C / min to room temperature.

[0027] Step 6: Prepare a fluorinated solution using perfluorooctyltriethoxysilane, SiO2 nanopowder, and an ethanol solution (use 96% (actually 95-99%) ethanol with a water content of approximately 4%) in a ratio of 4:2:94-6:4:90 (mass fraction). Spin coat the solution evenly onto the sample surface obtained in Step 4. The spin coating process parameters are as follows: the first stage is a speed of 480-520 rpm for 9-11 seconds, primarily for spreading; the second stage is increased to 1400-1600 rpm for 28-32 seconds, primarily for uniform coating; the third stage is increased to 1800-2200 rpm for 18-22 seconds, primarily for leveling; the spin coating is repeated 3-5 times.

[0028] Step 7: After the spin coating operation is completed, the sample is transferred to a conventional oven for subsequent heat treatment. The heat treatment is carried out at 38℃-42℃ for 28 minutes to 32 minutes, mainly for stress release; then the temperature is raised to 63℃-67℃ for 115 minutes to 125 minutes, mainly for structural stability; then the temperature is raised to 83℃-87℃ for 350 minutes to 370 minutes, mainly for performance enhancement; then the sample is cooled in the oven and taken out to obtain the finished product.

[0029] In step 2, the ultrasonic cleaning method is: using deionized water and anhydrous ethanol to clean the amination-treated carbon fibers respectively.

[0030] In step seven, the surface morphology and thickness of the sample can be controlled by changing the mass and number of times of adding the mixed solution obtained in step five, and the final thickness is 30-50 μm.

[0031] A method for improving thermal cycle cracking of an electrothermal anti-icing device is used in the surface protection of engineering equipment, wherein the engineering equipment includes transportation equipment such as aerospace vehicle skins and high-speed train pantographs, or energy infrastructure such as wind turbine blades and high-voltage transmission lines.

[0032] Compared with the prior art, the present invention has the following beneficial effects: In order to solve the technical problems of poor interface bonding, easy cracking during thermal cycles, and sharp increase in interface thermal resistance with increasing number of thermal cycles in existing electric heating anti-icing technologies, the present invention is based on electrospinning technology and a conductive fiber network structure modified with carbon fibers. Through material-structure-function collaborative design, it is driven by the electrospinning electric field force, optimizes the electrospinning parameters, constructs a carbon fiber network reinforced interface, combines surface functionalization modification, improves the mechanical interlocking and chemical bonding strength of the interface, and inhibits the crack propagation caused by thermal stress. At the same time, the directional arrangement of amino-modified carbon fibers in the polyurethane matrix is ​​achieved. At the same time, the directional arrangement structure can relieve thermal stress, achieve efficient longitudinal heat conduction, effectively reduce resistivity, and achieve good heating power density at low operating voltage. Finally, stabilizers and anti-hydrolysis agents are introduced into the polyurethane to make the performance degradation of the sample surface less than 10% after UV aging test.

[0033] The innovative design of the new composite network constructed with amino-treated carbon fibers provides an ideal material solution for the new generation of intelligent anti-icing systems.

[0034] The present invention provides a method for improving thermal cycle cracking in electric heating anti-icing devices. Laser etching is performed on a copper substrate. A thermoplastic polyurethane (TP) matrix is ​​formed on the copper substrate, and amino-modified carbon fibers are oriented within the TP matrix to form a conductive reinforcement layer (60-120 μm thick). Additives such as heat stabilizers and anti-hydrolysis agents are also added, and a 30-50 μm thick fluorinated polyurethane hydrophobic layer is applied to the surface. The fluorinated polyurethane hydrophobic layer exhibits a contact angle greater than 135°. This method effectively addresses key technical bottlenecks in existing electric heating anti-icing technology through a systematic material-structure-function collaborative design. Its innovation is mainly reflected in the following aspects: First, the copper sheet serving as the substrate is laser etched to give the surface periodically distributed microgrooves, which increases the specific surface area, provides mechanical anchoring points, and enhances the bonding force between the copper sheet and the substrate; second, through precise control of the electric field force of electrospinning, the amino-treated carbon fibers are directional arranged in the polyurethane matrix, constructing a conductive network and significantly reducing the resistivity, directly solving the problem of excessive energy consumption caused by the high resistivity of traditional technologies; secondly, the directionally arranged carbon fibers form a "highway"-like heat conduction path, solving the problem of uneven heat distribution; finally, thermal stabilizers and anti-hydrolysis agents are introduced into the polyurethane matrix, so that the surface performance of the electric heating anti-icing device can be maintained after UV aging, which is significantly lighter than metal heating elements while maintaining high tensile strength, thus balancing the contradiction between lightweight and durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is an optical micrograph of a metal substrate after pretreatment according to the present invention; Figure 2 The SEM photograph of the amino carbon fiber obtained by electrospinning in Example 1 of the present invention and the surface morphology of the fluorinated polyurethane hydrophobic layer; Figure 3 This is a SEM photograph of the amination carbon fiber obtained in Comparative Example 4 of the present invention; Figure 4 is the surface static water contact angle of the surface of the electrothermal anti-icing device, wherein (a) is Example 1; (b) is Comparative Example 2; Figure 5 is the ice bonding strength graph; Figure 6 It is a graph of the time it takes for the ice to separate from the sample surface and the solid-ice interface temperature at the time of separation; Figure 7 This is a SEM photograph of the surface morphology of the sample (cracked) obtained after 50 cycles in Comparative Example 4. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific examples. The following examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Example 1

[0037] A method for improving thermal cycle cracking of an electric heating anti-icing device comprises the following steps: Step 1: The first step is to pre-treat the metal substrate by laser etching. Laser etching is performed on the surface of the copper sheet to form surface microgrooves to increase the specific surface area, making it easier for electrospinning to be embedded in the grooves.

[0038] The copper sheet substrate is laser etched, and its surface has regular circular grooves with a depth of micrometers and a groove diameter of about 45-55μm.

[0039] Step 2: Pre-treat the carbon fibers. Select high-purity carbon fibers as the conductive reinforcement phase, with a diameter of 7-10 μm and a length of 30 μm.

[0040] The carbon fiber was placed in a 65% concentrated nitric acid solution, with the ratio of carbon fiber to 65% concentrated nitric acid being 1 g of carbon fiber corresponding to approximately 15 mL of 65% concentrated nitric acid. The solution was refluxed in a constant temperature water bath at 80°C for 4 hours to increase the surface carboxyl density and form a groove structure on the fiber surface.

[0041] Then, the oxidized carbon fibers were subjected to amino modification. The oxidized carbon fibers were immersed in a 5wt% silane coupling agent (KH550) ethanol solution (pH controlled at 9.5). To treat 1g of oxidized carbon fibers, 30mL of this 5wt% silane coupling agent (KH550) ethanol solution was required. Anhydrous ethanol was used. The solution was placed under a nitrogen atmosphere and heated to 80°C for 6 hours.

[0042] Then, the carbon fibers were ultrasonically cleaned with deionized water and anhydrous ethanol in sequence, taken out and vacuum dried, and sieved to obtain uniformly dispersed modified carbon fibers.

[0043] Step 3: Thermoplastic polyurethane (BASF Elastollan 1185A) was selected as the polymer matrix, and the ratio of different reactants was amino carbon fiber: 8.2wt% (mass fraction), polyurethane matrix: 91.1wt% (mass fraction), stabilizer about 0.5wt% and anti-hydrolysis agent about 0.2wt%.

[0044] Pre-mixing was performed using a high-speed shear emulsifier at a speed of 10,000 rpm for 5 minutes, followed by fine dispersion using a three-roll mill with a roller spacing of 50 μm, and degassing using a vacuum planetary mixer at 0.05 MPa for 30 minutes.

[0045] Step 4: The prepared spinning solution was electrospun at a spinning voltage of 16 kV, a receiving distance of 18 cm, a solution propulsion rate of 1.2 mL / h, a drum diameter of 200 mm, a rotation speed of 3200 rpm, a surface linear velocity of 33.5 m / s, and a temperature of 40°C. Multi-stage electric field control was employed, with a primary field strength of 1.8 kV / cm at the needle tip and a secondary field receiver bias of 3 kV.

[0046] The copper sheet obtained in step 1 is fixed on the drum, and the relative position of the copper sheet and the spinneret is adjusted to ensure that the surface deposition of the copper sheet is relatively uniform.

[0047] Step 5: Vacuum curing is performed, maintaining a vacuum degree of 0.1 MPa. A step-by-step curing process is employed: the first stage is 30 minutes at 40°C to relax the molecular chains; the second stage is 120 minutes at 65°C for pre-crosslinking; and the third stage is 360 minutes at 85°C for complete curing. The temperature is then lowered uniformly at 2°C / min to room temperature.

[0048] Step 6: Prepare a fluorinated solution using perfluorooctyltriethoxysilane, SiO2 nanopowder, and ethanol solution in a mass fraction of 5:3:92. Apply the solution evenly to the sample surface obtained in Step 4 using spin coating. The spin coating process parameters are as follows: first stage, 500 rpm for 10 seconds (primarily for spreading); second stage, 1500 rpm for 30 seconds (primarily for uniform coating); third stage, 2000 rpm for 20 seconds (primarily for leveling); and four spin coats.

[0049] Step 7: After the spin coating operation is completed, the sample is transferred to a common oven for subsequent heat treatment. The heat treatment is carried out at 40 ° C for 30 minutes, mainly for stress release; then the temperature is raised to 65 ° C for 120 minutes, mainly for structural stability; then the temperature is raised to 85 ° C for 360 minutes, mainly for performance enhancement; then the sample is cooled in the oven and taken out to obtain the finished product.

[0050] In the electrothermal anti-icing device obtained by a treatment method for improving thermal cycle cracking of an electrothermal anti-icing device according to this embodiment, a copper substrate is laser etched, and a thermoplastic polyurethane is used as a matrix on the copper substrate. Aminated carbon fibers are directionally arranged in the polyurethane matrix to form a conductive reinforcement layer (the conductive reinforcement layer is 80 μm thick). At the same time, additives such as heat stabilizers and anti-hydrolysis agents are added to the surface of the electrothermal anti-icing device, and a 40 μm thick fluorinated polyurethane hydrophobic layer is prepared on the surface.

[0051] A treatment method for improving thermal cycle cracking of an electrothermal anti-icing device according to this embodiment is applied to the surface protection of engineering equipment, wherein the engineering equipment includes transportation equipment such as aerospace vehicle skins and high-speed train pantographs, or energy infrastructure such as wind turbine blades and high-voltage transmission lines.

[0052] Comparative Example 1 A surface treatment method for an electrothermal anti-icing device comprises the following steps: Step 1: The first step is to pre-treat the metal substrate by laser etching. Laser etching is performed on the surface of the copper sheet to form surface microgrooves to increase the specific surface area, making it easier for electrospinning to be embedded in the grooves.

[0053] The copper sheet substrate is laser etched, and its surface has regular circular grooves with a depth of micrometers and a groove diameter of about 45-55μm.

[0054] Step 2: Thermoplastic polyurethane (BASF Elastollan 1185A) was selected as the polymer matrix, and the ratio of the different reactants was polyurethane matrix: 99.3 wt% (mass fraction), stabilizer about 0.5 wt% and anti-hydrolysis agent about 0.2 wt%.

[0055] Pre-mixing was performed using a high-speed shear emulsifier at a speed of 10,000 rpm for 5 minutes, followed by fine dispersion using a three-roll mill with a roller spacing of 50 μm, and degassing using a vacuum planetary mixer at 0.05 MPa for 30 minutes.

[0056] Step 3: The prepared spinning solution was electrospun at a spinning voltage of 16 kV, a receiving distance of 18 cm, a solution propulsion rate of 1.2 mL / h, a drum diameter of 200 mm, a rotation speed of 3200 rpm, a surface linear velocity of 33.5 m / s, and a temperature of 40°C. Multi-stage electric field control was employed, with a primary electric field strength of 1.8 kV / cm at the needle tip and a secondary electric field receiver bias of 3 kV.

[0057] The copper sheet obtained in step 1 is fixed on the drum, and the relative position of the copper sheet and the spinneret is adjusted to ensure that the surface deposition of the copper sheet is relatively uniform.

[0058] Step 4: Vacuum curing, maintaining a vacuum of 0.1 MPa. A step-by-step curing process is employed: the first stage is 30 minutes at 40°C to relax the molecular chains; the second stage is 120 minutes at 65°C for pre-crosslinking; and the third stage is 360 minutes at 85°C for complete curing. The temperature is then lowered to room temperature at a constant rate of 2°C / min.

[0059] Step 5: Prepare a fluorinated solution using perfluorooctyltriethoxysilane, SiO2 nanopowder, and ethanol solution in a mass fraction of 5:3:92. Apply the solution evenly to the sample surface obtained in Step 3 using spin coating. The spin coating process parameters are as follows: first stage, 500 rpm for 10 seconds (primarily for spreading); second stage, 1500 rpm for 30 seconds (primarily for uniform coating); third stage, 2000 rpm for 20 seconds (primarily for leveling); and four spin coats.

[0060] Step 6: After the spin coating operation is completed, the sample is transferred to a common oven for subsequent heat treatment. The heat treatment is carried out at 40 ° C for 30 minutes, mainly for stress release; then the temperature is raised to 65 ° C for 120 minutes, mainly for structural stability; then the temperature is raised to 85 ° C for 360 minutes, mainly for performance enhancement; then the sample is cooled in the oven and taken out to obtain the finished product.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that there are no steps 6 and 7, that is, no fluorinated modified polyurethane hydrophobic layer is added to the surface.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 1 is that no stabilizer and anti-hydrolysis agent are added when preparing the polyurethane solution in step 3.

[0065] Comparative Example 4

[0066] The difference between this comparative example and Example 1 is that in the electrospinning process in step 4, a static flat plate receiver is used, and a polyurethane layer with randomly distributed carbon fibers is obtained.

[0067] Comparative Example 5

[0068] The difference between this comparative example and Example 1 is that in step 5, a step-by-step curing process is adopted: the first stage is to keep warm at 35 degrees for 30 minutes; the second stage is to keep warm at 60 degrees for 130 minutes; and the third stage is to keep warm at 90 degrees for 320 minutes.

[0069] Characterization and test methods: (1) Optical microscope analysis: The surface morphology of the prepared samples was characterized using a Nikon microscope (optical microscope).

[0070] (2) Scanning electron microscopy analysis: The surface microstructure of the prepared samples was characterized using a JEOL-6360LV SEM, scanning at a voltage of 20 kV and a working distance of 10 mm. Because the sample surface is non-conductive, a platinum (Pt) layer was added to the surface before imaging to make it conductive.

[0071] (3) Static water contact angle test: The surface wettability of the samples was tested using a fully automatic optical contact angle meter (FTA200, First Ten Angstroms, USA). The test solvent was deionized water, the test droplet volume was 5µL, and the release rate was 1µL / s. Five locations were selected for testing on each sample, and the average value was calculated.

[0072] (4) Ice bonding strength test: Measurements are performed using the centrifugation method in a -20°C environmental chamber. A prepared sample / ice cube and a counterweight of equal mass are placed at either end of a rod and subjected to rotational acceleration. As the rod accelerates, the sample maintains centripetal acceleration. When the centrifugal force exceeds the ice bond strength between the sample and the ice cube, the sample separates from the ice cube, and the ice cube is ejected. The ice bond strength of the sample can then be calculated based on the ice mass, rod length, and test duration.

[0073] (5) Electric heating deicing efficiency test: In an environmental chamber at -20°C, the relative humidity range is 30–40%. Ice cubes of a certain size are prefabricated using silicone molds and further frozen onto the sample surface. Subsequently, the test is performed at the solid ice interface, where heat is applied. No external mechanical force is applied throughout the ice melting process, but shear forces may be generated at the interface due to the influence of gravity. The entire process is continuously recorded by a camera until the ice cube is completely detached. In addition, the temperature changes at the solid ice interface are closely monitored by thermocouples, and the energy consumption throughout the process is quantified. Three parallel tests are performed on each sample to ensure data accuracy.

[0074] (6) Interface thermal resistance test: The interface thermal resistance test method uses the ASTM D5470 test standard and uses the steady-state heat conduction method to measure the thermal resistance of the thermal conductive interface material.

[0075] Figure 1 An optical microscope photograph of the surface of the Cu sheet substrate of Example 1 after laser etching is given. It can be seen from the figure that the surface of the Cu sheet presents a regular undulating structure, and the diameter of the surface holes is about 45-55 μm.

[0076] Figure 2The SEM images of the amination carbon fibers obtained by electrospinning in Example 1 are given. Figure 2 As can be seen in (a), the carbon fibers obtained by electrospinning exhibit significant axial orientation and good fiber parallelism. Most fibers have diameters ranging from 7 to 10 μm, providing a large surface area. Figure 2 In (b), the surface morphology of the fluorinated modified polyurethane hydrophobic layer of this embodiment can be seen. The surface is very smooth and flat, without any obvious surface defects such as holes and cracks.

[0077] Figure 3 The SEM photograph of the amino carbon fiber obtained by electrospinning in Comparative Example 4 is given, which has a high inter-fiber porosity, a relatively uniform distribution of fiber spacing, and no obvious agglomeration phenomenon. The diameter of most fibers ranges from 7 to 10 μm.

[0078] Figure 4 The static water contact angle of the sample obtained in Example 1 is 145.1±1.8°, indicating good surface hydrophobicity. The static water contact angle of the sample in Comparative Example 2 is only 114.9±1.2°, significantly lower than that in Example 1.

[0079] Figure 5 The ice adhesion strength of Example 1 after 50 icing / deicing cycles is shown. The initial ice adhesion strength is 11.59±1.29 kPa, a relatively low value, reflecting the sample's good deicing ability. As the number of icing / deicing cycles increases, the ice adhesion strength increases slightly, reaching 12.92±1.31 kPa by the 15th cycle and gradually stabilizing. At the end of the 50 icing / deicing cycles, the ice adhesion strength is still only 14.03±1.63 kPa, demonstrating good anti-icing stability. For comparative example 3, the initial ice adhesion strength is 15.41±1.69 kPa, a slight improvement over Example 1, reflecting the sample's continued good deicing ability. The ice adhesion strength continued to rise significantly with the number of icing / deicing cycles, reaching 20.18±1.12 kPa at the 15th cycle and continued to rise steadily. By the end of 50 icing / deicing cycles, the ice adhesion strength had reached 33.67±1.41 kPa, demonstrating the significant effect of the stabilizer and anti-hydrolysis agent on the sample's anti-icing stability.

[0080] Figure 6The time it takes for ice to detach from the sample surface after the electric heating deicing process in Example 1 and the solid-ice interface temperature at the time of detachment are shown. The introduction of the conductive reinforcement layer significantly improves the deicing efficiency compared to Comparative Example 1 (a control sample without the conductive reinforcement layer). The deicing time is significantly shortened from 980 seconds to 367 seconds, and the solid-ice interface temperature at the time of ice detachment also increases from 4.01°C to 4.37°C. This demonstrates the excellent deicing efficiency of electric heating.

[0081] Comparative Example 4 (non-directional arrangement of amino carbon fibers in the conductive reinforcement layer) has an electric heating deicing time of 513s, and the solid-ice interface temperature when the ice cubes are separated from the sample surface is 4.18°C. The surface resistivity of the sample in Example 1 is significantly reduced compared to that in Comparative Example 4. The resistivity of Example 1 is approximately Ω·cm, while the resistivity of Comparative Example 4 was approximately 0.47 Ω·cm (resistivity measured using a four-probe method). The resistivity of Example 1 is much lower than that of Comparative Example 4. The low enough resistance of Example 1 can increase the heat generation rate per unit volume, ensuring more efficient Joule heating, while also significantly reducing energy consumption relative to electric heating.

[0082] Comparative Example 5 (different curing process), its electric heating deicing time is 490s, the solid-ice interface temperature when the ice cubes are separated from the sample surface is 4.25°C, and the resistivity of the sample of Example 1 is greatly reduced compared with that of Comparative Example 5. The resistivity of Example 1 is about Ω·cm, the resistivity of comparative example 5 is about Ω·cm.

[0083] Figure 7 The surface morphology SEM photos of the sample (cracked) obtained after 50 cycles of comparative example 4 are given as follows: Figure 7 As shown, obvious cracking occurred on the surface of the sample.

[0084] In contrast, during 50 cycles, the interface thermal resistance of Example 1 of the present invention increased from 8.2 ± 0.3 mm²·K / W in the initial state to 8.5 ± 0.4 mm²·K / W after 10 cycles, 8.9 ± 0.5 mm²·K / W after 20 cycles, 9.2 ± 0.6 mm²·K / W after 30 cycles, 9.6 ± 0.6 mm²·K / W after 40 cycles, and 9.8 ± 0.8 mm²·K / W after 50 cycles. The increase was relatively small, and the surface of the sample obtained from Example 1 after 50 cycles did not crack.

[0085] In contrast, in Comparative Example 4, which did not use electrospinning to add aligned amino carbon fibers, the thermal resistance increased continuously from 8.2 ± 0.3 mm²·K / W to 25.4 ± 1.1 mm²·K / W after 50 cycles. The increase was large, and the sample surface showed the following changes: Figure 7 The cracking condition shown.

[0086] In this embodiment 1, the resistivity of the electrothermal anti-icing material is relatively low (approximately The combination of a low-power CMOS process and a moderate thermal resistance (about 8.2 ± 0.3 mm²·K / W) can generally meet the requirements of electric deicing.

[0087] Example 2 A method for improving thermal cycle cracking of an electric heating anti-icing device comprises the following steps: Step 1: The first step is to pre-treat the metal substrate by laser etching. Laser etching is performed on the surface of the copper sheet to form surface microgrooves to increase the specific surface area, making it easier for electrospinning to be embedded in the grooves.

[0088] The copper sheet substrate is laser etched, and its surface has regular circular grooves with a depth of micrometers and a groove diameter of about 45-55μm.

[0089] Step 2: Pre-treat the carbon fibers. Select high-purity carbon fibers as the conductive reinforcement phase, with a diameter of 7-10 μm and a length of 30 μm.

[0090] The carbon fiber was placed in a 60% concentrated nitric acid solution, with the ratio of carbon fiber to 60% concentrated nitric acid being 0.9 g of carbon fiber corresponding to approximately 13 mL of 60% concentrated nitric acid. The solution was refluxed in a constant temperature water bath at 75°C for 3.5 hours to increase the surface carboxyl density and form a groove structure on the fiber surface.

[0091] Then, the oxidized carbon fibers were subjected to amino modification. The oxidized carbon fibers were immersed in a 4wt% silane coupling agent (KH550) ethanol solution (pH controlled at 9.0). Typically, 20mL of this 4wt% silane coupling agent (KH550) ethanol solution was required to treat 1g of oxidized carbon fibers. Anhydrous ethanol was used. The solution was placed under a nitrogen atmosphere and heated to 75°C for 5 hours.

[0092] Then, the carbon fibers were ultrasonically cleaned with deionized water and anhydrous ethanol in sequence, taken out and vacuum dried, and sieved to obtain uniformly dispersed modified carbon fibers.

[0093] Step 3: Thermoplastic polyurethane (BASF Elastollan 1185A) was selected as the polymer matrix, and the ratio of different reactants was amino carbon fiber: 8.0wt% (mass fraction), polyurethane matrix: 91.45wt% (mass fraction), stabilizer about 0.4wt% and anti-hydrolysis agent about 0.15wt%.

[0094] Pre-mixing was performed using a high-speed shear emulsifier at 9000 rpm for 4 minutes, followed by fine dispersion using a three-roll mill with a roller spacing of 48 μm, and degassing using a vacuum planetary mixer at 0.04 MPa for 28 minutes.

[0095] Step 4: The prepared spinning solution was electrospun at a spinning voltage of 15.5 kV, a receiving distance of 17.5 cm, a solution propulsion rate of 1.1 mL / h, a drum diameter of 195 mm, a rotation speed of 2800 rpm, a surface linear velocity of 33.0 m / s, and a temperature of 38°C. Multi-stage electric field control was employed, with a primary electric field strength of 1.7 kV / cm at the needle tip and a secondary electric field receiver bias of 2.8 kV.

[0096] The copper sheet obtained in step 1 is fixed on the drum, and the relative position of the copper sheet and the spinneret is adjusted to ensure that the surface deposition of the copper sheet is relatively uniform.

[0097] Step 5: Vacuum curing is performed, maintaining a vacuum of 0.09 MPa. A step-by-step curing process is employed: the first stage is 28 minutes at 38°C to relax the molecular chains; the second stage is 115 minutes at 63°C for pre-crosslinking; and the third stage is 350 minutes at 83°C for complete curing. The temperature is then lowered to room temperature at a constant rate of 1.9°C / min.

[0098] Step 6: Prepare a fluorinated solution using perfluorooctyltriethoxysilane, SiO2 nanopowder, and ethanol solution in a mass fraction of 4:2:94. Spin coat the solution evenly onto the sample surface obtained in Step 4. The spin coating process parameters are as follows: first stage: 480 rpm for 9 seconds (primarily for spreading); second stage: 1400 rpm for 28 seconds (primarily for uniform coating); third stage: 1800 rpm for 18 seconds (primarily for leveling); and three spin coats.

[0099] Step 7: After the spin coating operation is completed, the sample is transferred to a common oven for subsequent heat treatment. The heat treatment is carried out at 38 ° C for 28 minutes, mainly for stress release; then the temperature is raised to 63 ° C for 115 minutes, mainly for structural stability; then the temperature is raised to 83 ° C for 350 minutes, mainly for performance enhancement; then the sample is cooled in the oven and taken out to obtain the finished product.

[0100] In the electrothermal anti-icing device obtained by a treatment method for improving thermal cycle cracking of an electrothermal anti-icing device according to this embodiment, a copper substrate is laser etched, and a thermoplastic polyurethane is used as a matrix on the copper substrate. Aminated carbon fibers are directionally arranged in the polyurethane matrix to form a conductive reinforcement layer (the conductive reinforcement layer has a thickness of 60 μm). Additives such as a heat stabilizer and an anti-hydrolysis agent are also added, and a 30 μm thick fluorinated polyurethane hydrophobic layer is prepared on the surface.

[0101] A treatment method for improving thermal cycle cracking of an electrothermal anti-icing device according to this embodiment is applied to the surface protection of engineering equipment, wherein the engineering equipment includes transportation equipment such as aerospace vehicle skins and high-speed train pantographs, or energy infrastructure such as wind turbine blades and high-voltage transmission lines.

[0102] Example 3

[0103] A method for improving thermal cycle cracking of an electric heating anti-icing device comprises the following steps: Step 1: The first step is to pre-treat the metal substrate by laser etching. Laser etching is performed on the surface of the copper sheet to form surface microgrooves to increase the specific surface area, making it easier for electrospinning to be embedded in the grooves.

[0104] The copper sheet substrate is laser etched, and its surface has regular circular grooves with a depth of micrometers and a groove diameter of about 45-55μm.

[0105] Step 2: Pre-treat the carbon fibers. Select high-purity carbon fibers as the conductive reinforcement phase, with a diameter of 7-10 μm and a length of 30 μm.

[0106] The carbon fiber was placed in a 70% concentrated nitric acid solution, with the ratio of carbon fiber to 70% concentrated nitric acid being 1.1 g of carbon fiber corresponding to approximately 17 mL of 70% concentrated nitric acid. The solution was refluxed in a constant temperature water bath at 85°C for 4.5 hours to increase the surface carboxyl density and form a groove structure on the fiber surface.

[0107] Then, the oxidized carbon fibers were subjected to amino modification. The oxidized carbon fibers were immersed in a 6wt% silane coupling agent (KH550) ethanol solution (pH controlled at 10.0). To treat 1g of oxidized carbon fibers, 50mL of this 6wt% silane coupling agent (KH550) ethanol solution was required. Anhydrous ethanol was used. The solution was placed under a nitrogen atmosphere and heated to 85°C for 7 hours.

[0108] Then, the carbon fibers were ultrasonically cleaned with deionized water and anhydrous ethanol in sequence, taken out and vacuum dried, and sieved to obtain uniformly dispersed modified carbon fibers.

[0109] Step 3: Thermoplastic polyurethane (BASF Elastollan 1185A) was selected as the polymer matrix, and the ratio of different reactants was amino carbon fiber: 8.4wt% (mass fraction), polyurethane matrix: 90.75wt% (mass fraction), stabilizer about 0.6wt% and anti-hydrolysis agent about 0.25wt%.

[0110] Pre-mixing was performed using a high-speed shear emulsifier at 11,000 rpm for 6 minutes, followed by fine dispersion using a three-roll mill with a roller spacing of 52 μm. Degassing was performed using a vacuum planetary mixer at 0.06 MPa for 32 minutes.

[0111] Step 4: The prepared spinning solution was electrospun at a spinning voltage of 16.5 kV, a receiving distance of 18.5 cm, a solution propulsion rate of 1.3 mL / h, a drum diameter of 205 mm, a rotation speed of 3400 rpm, a surface linear velocity of 34.0 m / s, and a temperature of 42°C. Multi-stage electric field control was employed, with a primary electric field strength of 1.9 kV / cm at the needle tip and a secondary electric field receiver bias of 3.2 kV.

[0112] The copper sheet obtained in step 1 is fixed on the drum, and the relative position of the copper sheet and the spinneret is adjusted to ensure that the surface deposition of the copper sheet is relatively uniform.

[0113] Step 5: Vacuum curing is performed, maintaining a vacuum degree of 0.11 MPa. A step-by-step curing process is employed: the first stage is 32 minutes at 42°C to relax the molecular chains; the second stage is 125 minutes at 67°C for pre-crosslinking; and the third stage is 370 minutes at 87°C for complete curing. The temperature is then lowered to room temperature at a constant rate of 2.1°C / min.

[0114] Step 6: Prepare a fluorinated solution using perfluorooctyltriethoxysilane, SiO2 nanopowder, and ethanol solution in a mass fraction of 6:4:90. Apply the solution evenly to the sample surface obtained in Step 4 using spin coating. The spin coating process parameters are as follows: first stage: 520 rpm for 11 seconds (primarily for spreading); second stage: 1600 rpm for 32 seconds (primarily for uniform coating); third stage: 2200 rpm for 22 seconds (primarily for leveling); and five spin coating passes.

[0115] Step 7: After the spin coating operation is completed, the sample is transferred to a common oven for subsequent heat treatment. The heat treatment is carried out at 42 ° C for 32 minutes, mainly for stress release; then the temperature is raised to 67 ° C for 125 minutes, mainly for structural stability; then the temperature is raised to 87 ° C for 370 minutes, mainly for performance enhancement; then the sample is cooled in the oven and taken out to obtain the finished product.

[0116] In the electrothermal anti-icing device obtained by a treatment method for improving thermal cycle cracking of an electrothermal anti-icing device according to this embodiment, a copper substrate is laser etched, and a thermoplastic polyurethane is used as a matrix on the copper substrate. Aminated carbon fibers are directionally arranged in the polyurethane matrix to form a conductive reinforcement layer (the conductive reinforcement layer has a thickness of 120 μm). Additives such as a heat stabilizer and an anti-hydrolysis agent are also added, and a 50 μm thick fluorinated polyurethane hydrophobic layer is prepared on the surface.

[0117] A treatment method for improving thermal cycle cracking of an electrothermal anti-icing device according to this embodiment is applied to the surface protection of engineering equipment, wherein the engineering equipment includes transportation equipment such as aerospace vehicle skins and high-speed train pantographs, or energy infrastructure such as wind turbine blades and high-voltage transmission lines.

[0118] It should be understood that in order to streamline the present disclosure and aid understanding of one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all of the features of the previously disclosed embodiments. Accordingly, the claims that follow the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the invention.

[0119] Although the present invention has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the foregoing description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Consequently, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative rather than restrictive of the scope of the invention, which is defined by the appended claims.

[0120] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An electric heating anti-icing device, characterized in that: Thermoplastic polyurethane is prepared as a matrix on the metal substrate of the electric thermal anti-icing device. Aminated carbon fibers are directionally arranged in the matrix to form a conductive reinforcement layer. Thermal stabilizers and anti-hydrolysis agents are added to the conductive reinforcement layer, and a hydrophobic layer is provided on the surface of the conductive reinforcement layer.

2. The electric heating anti-icing device according to claim 1, characterized in that: The thickness of the conductive reinforcement layer is 60-120 μm; the metal substrate includes a copper sheet.

3. The electric heating anti-icing device according to claim 1, characterized in that: The hydrophobic layer is a fluorinated modified polyurethane hydrophobic layer, and the thickness of the hydrophobic layer is 30-50 μm.

4. The electrothermal anti-icing device according to claim 1, characterized in that: The heat stabilizer includes the hindered amine light stabilizer Tinuvin 770; the anti-hydrolysis agent includes Stabaxol P200; and the thermoplastic polyurethane includes BASF Elastollan 1185A.

5. A method for improving thermal cycle cracking of the electrothermal anti-icing device according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Pretreatment of metal substrate; Step 2: placing the carbon fiber in a 60-70% concentrated nitric acid solution and refluxing in a constant temperature water bath at 75-85°C for 3.5-4.5 hours; the ratio of the carbon fiber to the 60-70% concentrated nitric acid is 0.9-1.1 g of carbon fiber corresponding to 13-17 mL of 60-70% concentrated nitric acid to obtain oxidized carbon fiber; Immerse the oxidized carbon fiber in a 4-6wt% silane coupling agent KH550 ethanol solution. The pH value of the solution is controlled between 9-10. 20-50 mL of 4-6wt% silane coupling agent KH550 ethanol solution is required to treat 1 g of oxidized carbon fiber. Place the modified carbon fiber under nitrogen atmosphere and heat it to 75-85°C for 5-7 hours. Then, the modified carbon fibers were cleaned with deionized water and anhydrous ethanol in turn by ultrasonic cleaning, vacuum dried, and sieved to obtain uniformly dispersed modified carbon fibers, namely, amino-treated carbon fibers. Step 3: The spinning solution ratio is 8-8.4wt% of amino carbon fiber, 90.75-91.45wt% of matrix, 0.4-0.6wt% of stabilizer and 0.15-0.25wt% of anti-hydrolysis agent; then pre-mixed using a high-speed shear emulsifier; Step 4: Electrospinning the prepared spinning solution, and fixing the metal substrate pretreated in step 1 on the drum; wherein the spinning voltage is 16±0.5kV, the receiving distance is 18±0.5cm, the solution advancing rate is 1.1-1.3mL / h, the drum diameter is 195-205mm, the rotation speed is 2800-3400rpm, the surface linear velocity is maintained at 33.0-34.0m / s, and the temperature is controlled at 40±2°C; and multi-level electric field control is adopted, wherein the field strength at the needle tip in the primary electric field is 1.7-1.9kV / cm, and the secondary electric field receiver has an additional bias voltage of 2.8-3.2kV; Step 5: Perform vacuum curing treatment, maintaining the vacuum degree at 0.09-0.11MPa; adopt a step-by-step curing process: Stage 1: Keep warm at 38-42°C for 28-32 minutes; Stage 2: Keep warm at 63-67°C for 115-125 minutes; Stage 3: Keep warm at 83-87℃ for 350-370min; Then, the temperature is uniformly lowered at 1.9-2.1°C / min to room temperature to obtain a conductive reinforcement layer; Step 6: Prepare a fluorination modification solution using perfluorooctyltriethoxysilane, SiO2 nanopowder, and ethanol solution, wherein the mass fraction ratio of the three is 4:2:94-6:4:90; use a spin coating method to evenly apply the prepared fluorination modification solution to the surface of the sample obtained in step 4; The spin coating process parameters are: Stage 1: speed 480-520 rpm, duration 9-11 seconds; The second stage: the speed is increased to 1400-1600 rpm, and the duration is 28-32 seconds; The third stage: the speed increases to 1800-2200 rpm and lasts for 18-22 seconds; The number of spin coating is 3 to 5 times; Step 7: After the spin coating operation is completed, transfer the sample to an oven for subsequent heat treatment, heat treatment at 38-42°C for 28-32 minutes; then heat to 63-67°C for 115-125 minutes; then heat to 83-87°C for 350-370 minutes; then cool in the oven, take out the sample, and obtain the finished product.

6. The processing method according to claim 5, characterized in that: In step 1, the surface of the metal substrate is laser etched to form surface grooves with a depth of micrometers and a diameter of 45-55 μm.

7. The processing method according to claim 5, characterized in that In step 2, the ethanol is anhydrous ethanol; in step 6, the ethanol solution is 95-99% ethanol.

8. The processing method according to claim 5, characterized in that In step three, the pre-mixing process is: the rotation speed is 9000-11000 rpm, the time is 4-6 minutes; then fine dispersion is carried out using a three-roll mill, the roller spacing is maintained at 48-52 μm, and degassing treatment is carried out using a vacuum planetary mixer with a parameter of 0.04-0.06 MPa and a processing time of 28-32 minutes.

9. Use of the treatment method according to any one of claims 5 to 8 in surface protection of engineering equipment.

10. The use according to claim 9, characterized in that Engineering equipment includes aerospace vehicle skins, high-speed train pantographs, wind turbine blades, and high-voltage transmission lines.

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