Method for inducing secondary penetration of resin based on laser CFRP interface pretreatment

Abstract

The present application relates to the technical field of composite material interface reinforcement, namely a method for inducing resin secondary penetration based on laser CFRP interface pretreatment: nanosecond pulse fiber laser is used to scan and process the CFRP substrate surface to be glued, macro flow channels are formed, the resin layer in the channels is completely removed, carbon fibers or glass fibers are exposed, and a primary structure is formed; ultrafast laser is used to scan the surface of the macro flow channels to form nanometer corrugations or micron-level dendritic fractals of a secondary structure; resin cement is uniformly placed on the surfaces of the secondary structures arranged in an upper and lower layer splicing mode to obtain a CFRP-cement-CFRP structure joint; and the CFRP-cement-CFRP structure joint is subjected to heat pressing treatment. The present application constructs a composite micro-nano structure of "primary structure+secondary structure" in layers on the CFRP surface, significantly promotes the macro spreading and micro penetration of the adhesive, and enhances the interface mechanical engagement and chemical combination capacity.

Description

Technical Field

[0001] This invention relates to the field of composite material interface reinforcement technology, specifically a method for inducing secondary resin infiltration based on laser CFRP interface pretreatment. Background Technology

[0002] With the pursuit of lightweight structures, "lightweight and high-strength" carbon fiber reinforced resin-based CFRP composites are attracting more and more attention in industries such as aerospace and automobiles. Adhesive-bonded integral composite structures, such as secondary bonding and adhesive co-curing, are beneficial for obtaining smooth aerodynamic shapes and can significantly reduce structural weight, thus becoming the main form of composite structure applications.

[0003] However, due to the limited number of surface-active functional groups, low surface energy, high inertness, and smooth surface of CFRP composites, they are difficult to bond with resin during bonding, affecting adhesive strength. Therefore, surface treatment of CFRP composites is necessary before bonding. The interfacial adhesive strength and durability of CFRP composites are limited by the dense structure of the resin surface and poor fiber wettability. To improve the interfacial adhesive strength and durability of CFRP composites, traditional laser pretreatment methods are commonly used. However, the modified structure processed on the CFRP composite surface by this method is mostly a single-layer structure, which is difficult to balance the rapid spreading and deep penetration of the adhesive, resulting in insufficient interfacial bonding. Therefore, there is an urgent need to develop a method based on laser CFRP interfacial pretreatment to induce secondary resin penetration to improve interfacial performance. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for inducing secondary resin penetration based on laser CFRP interface pretreatment. By constructing a composite micro / nano structure of "primary structure + secondary structure" on the CFRP surface in layers, the macroscopic spreading and microscopic penetration of the adhesive are significantly promoted, thereby enhancing the mechanical interlocking and chemical bonding capabilities of the interface.

[0005] To solve the above-mentioned technical problems, the present invention provides a method for inducing secondary resin permeation based on laser CFRP interface pretreatment, comprising the following steps: Nanosecond pulsed fiber lasers are used to scan and process the CFRP matrix surface to be bonded, forming macroscopic flow channels. By completely removing the resin layer in the channels and exposing carbon fibers or glass fibers, a primary structure is formed. The resin removal depth accounts for 10% to 30% of the total thickness of the CFRP matrix, the depth of the macroscopic flow channels is 50% to 100% of the resin removal depth, the width of the macroscopic flow channels is 100 μm to 500 μm, and the periodic spacing of the macroscopic flow channels is 200 μm to 500 μm. Ultrafast lasers are used to scan the surface of macroscopic flow channels to form secondary structures with nano-waves or micron-scale dendritic fractals with periods of 400nm~1000nm. The resin binder is evenly placed on the secondary structure surface of the interface between the upper and lower CFRP layers to obtain a CFRP-binder-CFRP structural joint. The CFRP-bondant-CFRP structural joint is subjected to hot pressing treatment.

[0006] Large-scale channels were fabricated at the bonding sites of the CFRP matrix using nanosecond pulsed fiber lasers, providing a continuous macroscopic flow channel for the adhesive. Simultaneously, by completely removing the resin layer to expose the carbon or glass fibers, air bubble retention was avoided, improving the primary penetration efficiency of the adhesive. Then, ultrafast lasers were used to fabricate nano-waves or micron-scale dendritic fractal secondary structures on the surface of the macroscopic flow channels. The capillary force of the nano-waves or micron-scale dendritic fractals in the secondary structures drove the adhesive to penetrate secondaryly, increasing the effective contact area between the adhesive and the carbon fiber and resin interfaces, strengthening physical anchoring and chemical bonding. The resin binder was placed between the upper and lower layers of the spliced ​​secondary structures. Through the layered structural design of the primary and secondary structures, both macroscopic adhesive flow channels and micro / nano-scale capillary-driven structures were considered, achieving a dual improvement in the depth and uniformity of adhesive penetration. The adhesive at the CFRP-binder-CFRP structural joint was treated with hot pressing. During curing, the adhesive fully filled the primary and secondary structures, achieving high-strength interfacial bonding through the combined action of mechanical locking and chemical bonding.

[0007] Preferably, the processing path of the nanosecond pulsed fiber laser adopts unidirectional parallel line scanning or grid scanning, and the scanning interval is consistent with the diameter of the laser focusing spot used to ensure that the resin on the CFRP surface is completely removed, so that the carbon fiber or glass fiber is exposed. After scanning, the scanning interval and number of times of the nanosecond pulsed fiber laser are changed according to the width and period of the required macroscopic flow channel to process the size of the specific macroscopic flow channel required.

[0008] Preferably, the parameters for fabricating the nanosecond pulsed fiber laser to achieve the required primary structure are as follows: The wavelength is 355nm~10.6μm, the power is 20W~150W, the pulse frequency is 1kHz~100kHz, the scanning speed is 100mm / s~1000mm / s, and the spot diameter is 50μm~100μm.

[0009] The laser energy density obtained by using the nanosecond pulsed fiber laser parameters given here should match the thermophysical properties of the resin and fiber on the CFRP surface, i.e., the laser energy density should be greater than the resin damage threshold and less than the carbon fiber damage threshold, so as to ensure that the resin is removed to a certain depth without damaging the carbon fiber, thereby providing a macroscopic adhesive flow path and exposing the carbon fiber or glass fiber surface.

[0010] Preferably, the secondary structure is formed by periodically processing nano-waves or micron-scale dendritic fractal structures with a spacing of 5μm to 10μm on the inner wall of the primary structure trench using parallel paths. This is to create a periodic nano-wave or micron-scale dendritic fractal structure. To form a capillary structure that facilitates secondary penetration of the binder, a spacing smaller than 5μm to 10μm would be limited by the processing technology and cannot be achieved; a spacing larger than 5μm to 10μm would not create the desired capillary effect.

[0011] Preferably, in order to achieve the required secondary structure processing, the parameters of the ultrafast laser are as follows: The pulse width is 50 fs to 10 ps, ​​the wavelength is 180 nm to 600 nm, the power is 1 W to 100 W, the pulse frequency is 100 kHz to 5000 kHz, the scanning speed is 1000 mm / s to 4000 mm / s, and the spot diameter is 20 μm to 40 μm. It is used to enhance capillary effect and promote secondary penetration of adhesives.

[0012] Preferably, the scanning angles of the nanosecond pulsed fiber laser and the ultrafast laser are both adjusted according to the layup direction of the CFRP matrix to avoid mechanical cutting of the carbon fibers and ensure structural integrity.

[0013] Preferably, the resin binder and the CFRP matrix resin are from the same resin system. When the CFRP matrix is ​​epoxy resin, the binder is epoxy resin; when the CFRP matrix is ​​bismaleimide resin, the binder is bismaleimide resin.

[0014] Preferably, the CFRP matrix is ​​a thermosetting composite material made of epoxy resin or phenolic resin and carbon fiber or glass fiber.

[0015] Preferably, the parameters for the hot-press curing process are: The curing heating rate is 0.5℃ / min to 3℃ / min; the curing holding time is 120min to 150min; the curing temperature is 178℃; the curing pressure is 0.05MPa to 0.3MPa; the cooling rate is 0.5℃ / min to 3℃ / min; and the cooling temperature is below 70℃.

[0016] Under the pressure and heat of the hot press, the adhesive melts and is rapidly filled through the macroscopic flow channels of the primary structure. It also achieves deep penetration through the capillary force of the secondary structure, significantly enhancing the interfacial bonding strength of CFRP-CFRP. This allows the adhesive to fully fill the primary and secondary structures during the curing process, achieving high-strength interfacial bonding through the combined action of mechanical locking and chemical bonding.

[0017] Preferably, the thickness of the resin binder is 0.15 mm to 0.7 mm.

[0018] A specific thickness of resin binder is required to allow it to fully penetrate the processed structure after melting, making the joint and the substrate a unified whole. If the thickness is too thick, a substrate-resin-substrate structure will form at the joint, and the strength of the resin will be insufficient, resulting in low joint strength. If the thickness is too thin, there will be insufficient adhesive to completely fill the microstructure, which will also reduce the joint strength.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes nanosecond lasers to fabricate a primary structure with macroscopic flow channels on the CFRP surface to be bonded. This primary structure provides a rapid and continuous macroscopic flow channel for the adhesive. Simultaneously, by completely removing the resin layer and exposing the carbon fibers, air bubble retention is avoided, improving the primary penetration efficiency of the adhesive. Then, an ultrafast laser is used to obtain a secondary structure with nano-ripples or micron-scale dendritic fractals on the surface of the primary structure of the macroscopic flow channels. In other words, a composite micro / nano structure is formed on the CFRP surface to be bonded. This facilitates secondary penetration of the adhesive through capillary forces, increases the effective contact area between the adhesive and the carbon fiber or glass fiber and resin interface, strengthens physical anchoring and chemical bonding, and ultimately improves the bonding strength of the CFRP under the combined effect of the composite structure.

[0020] Then, a resin binder is evenly placed between the upper and lower layers of the spliced ​​secondary structure to obtain a CFRP-binder-CFRP structural joint, which significantly promotes the macroscopic spreading and microscopic penetration of the adhesive. By hot-pressing the adhesive at the CFRP-binder-CFRP structural joint, the adhesive will fully fill the primary and secondary structures during the curing process. Through the combined action of mechanical locking and chemical bonding, high-strength interfacial bonding is achieved. Under the combined action of the composite structure, the bonding strength of CFRP is ultimately improved.

[0021] The CFRP interface enhancement pretreatment method based on laser-induced resin secondary infiltration provided by this invention has a reasonable process design, strong operability, and wide applicability. It can effectively solve the problems of low connection strength and poor fatigue resistance of CFRP adhesive components, and can realize the high load and long-term safe operation of CFRP adhesive components. Attached Figure Description

[0022] Figure 1 This is a schematic cross-sectional view of the CFRP adhesive surface with "primary structure + secondary structure" disclosed in the embodiments of the present invention.

[0023] Figure 2 This is a schematic diagram of the cross-section of a CFRP adhesive joint implemented using the technology disclosed in an embodiment of the present invention.

[0024] Figure 3 The cross section of the CFRP adhesive joint implemented using this technology is disclosed in the embodiments of the present invention.

[0025] Figure 4 This is a comparison of the CFRP bonding performance before and after treatment in Example 1 and Comparative Example 1.

[0026] The attached figures are labeled as follows: 1. CFRP matrix; 11. Carbon fiber; 12. Resin; 13. "Primary + Secondary" structure; 2. CFRP-bondant-CFRP structural joint; 21. CFRP matrix in the joint; 22. Resin adhesive; 3. CFRP bonded sample; 31. CFRP matrix in the bonded part; 32. Bonded cross section. Detailed Implementation

[0027] To make the above-mentioned objectives, features, and advantages of the embodiments of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in Embodiments 1 to 3, preferred embodiments are described in this invention to avoid redundancy. However, this invention is not limited to these, but can be specifically implemented in other ways within the scope of the technical solutions defined in the appended claims.

[0029] The technical solution of the present invention will be further illustrated below with specific examples.

[0030] In the following embodiments, unless otherwise specified, the methods described are conventional methods, and the reagents described are commercially available unless otherwise specified.

[0031] The method for inducing secondary resin penetration based on laser CFRP interface pretreatment provided by this invention improves the primary penetration efficiency of the adhesive during CFRP bonding by processing an upper and lower layered two-dimensional composite structure at the CFRP joint. The adhesive is then driven to penetrate secondaryly by capillary force, increasing the effective contact area between the adhesive and the carbon fiber and resin interface, strengthening physical anchoring and chemical bonding, thereby achieving high-strength CFRP bonding.

[0032] The CFRP matrix used in the following embodiments is a thermosetting composite material made of epoxy resin or phenolic resin and carbon fiber or glass fiber. The epoxy resin or phenolic resin and carbon fiber or glass fiber can be combined arbitrarily. The CFRP matrix used in the following embodiments is a carbon fiber reinforced epoxy resin composite material. In addition, the resin binder can be selected according to actual needs. The resin binder given in this embodiment is Loctite EA7000 050N WAERO resin binder.

[0033] Example 1 A method for inducing secondary resin permeation based on laser CFRP interface pretreatment includes the following steps: A nanosecond pulsed fiber laser with a wavelength of 355nm, a power of 20W, a pulse frequency of 1kHz, a scanning speed of 100mm / s, and a spot diameter of 50μm was used to perform unidirectional parallel line scanning on the bonding location of the carbon fiber reinforced epoxy resin matrix composite 1, forming macroscopic flow channels. The resin layer within the channels was scanned once or multiple times to achieve a predetermined resin removal thickness. After completely removing the resin 12 and exposing the surface of the carbon fiber 11, a primary structure with macroscopic flow channels was obtained. The depth of complete resin removal 12 was 10% of the thickness of the carbon fiber reinforced epoxy resin matrix composite 1, and the depth of the macroscopic flow channels was 50% of the resin removal depth, i.e., 2mm thick resin. Then, according to the above laser parameters, the areas where channels need to be formed were processed into a channel array with a width of 100μm, a period of 200μm, and a depth of 1mm. Figure 1 As shown.

[0034] An ultrafast laser with a pulse width of 50 fs, a wavelength of 180 nm, a power of 1 W, a pulse frequency of 300 kHz, a scanning speed of 1000 mm / s, and a spot diameter of 20 μm was used to perform parallel path scanning on the surface of a macroscopic flow channel to form a secondary structure with a period of 400 nm, consisting of nano-waves or micron-scale dendritic fractals. The periodic processing spacing of the nano-waves or micron-scale dendritic fractals in this secondary structure is 5 μm, resulting in a "primary + secondary" structure.

[0035] Loctite EA7000 050N WAERO resin binder 22 is evenly placed on the surface of the upper and lower spliced ​​secondary structure to obtain the CFRP-binder-CFRP structural joint 2, wherein the thickness of Loctite EA7000 050N WAERO resin binder 22 is 0.15mm. In the CFRP-binder-CFRP structural joint 2, the structure in which Loctite EA7000 050N WAERO resin binder 22 is not evenly placed is the CFRP matrix 21 in the joint, such as... Figure 2 As shown.

[0036] The CFRP-adhesive-CFRP structural joint was cured at a pressure of 0.05 MPa, with the temperature increased from room temperature to 178°C at a rate of 0.5°C / min. After curing and holding at this temperature for 120 minutes, the temperature was then decreased from 178°C to 70°C at a rate of 0.5°C / min to complete the curing process, resulting in CFRP bonded sample 3. Figure 3 As shown in (a), Figure 3 (b) is a cross-sectional view of 3(a), where 31 is the CFRP matrix in the adhesive component and 32 is the adhesive cross-section.

[0037] Example 2 A method for inducing secondary resin permeation based on laser CFRP interface pretreatment includes the following steps: A nanosecond pulsed fiber laser with a wavelength of 1064nm, a power of 80W, a pulse frequency of 20kHz, a scanning speed of 500mm / s, and a spot diameter of 80μm is used to perform unidirectional parallel line scanning processing on the bonding location of the carbon fiber reinforced epoxy resin matrix composite 1. This forms a macroscopic flow channel. The resin layer within the channel is scanned once or multiple times to reach a predetermined resin removal thickness. After the resin 12 is completely removed and the surface of the carbon fiber 11 is exposed, a primary structure with macroscopic flow channels is obtained. The depth of the complete removal of resin 12 is 20% of the thickness of the carbon fiber reinforced epoxy resin matrix composite 1, and the depth of the macroscopic flow channel is 80% of the resin 12 removal depth. Then, according to the above laser parameters, the areas where channels need to be formed are processed into a channel array with a width of 200μm, a period of 300μm, and a depth of 1mm.

[0038] An ultrafast laser with a pulse width of 100 fs, a wavelength of 500 nm, a power of 5 W, a pulse frequency of 100 kHz, a scanning speed of 3000 mm / s, and a spot diameter of 30 μm was used to perform parallel path scanning on the surface of a macroscopic flow channel to form a secondary structure with a period of 800 nm, consisting of nano-waves or micron-scale dendritic fractals. The periodic processing spacing of the nano-waves or micron-scale dendritic fractals in this secondary structure is 8 μm, resulting in a "primary + secondary" structure.

[0039] Loctite EA7000 050N WAERO resin binder 22 is evenly placed on the surface of the upper and lower spliced ​​secondary structure to obtain the CFRP-binder-CFRP structure joint 2, wherein the thickness of the Loctite EA7000 050N WAERO resin binder is 0.5mm. The structure in the CFRP-binder-CFRP structure joint 2 where the Loctite EA7000 050N WAERO resin binder 22 is not evenly placed is the CFRP matrix 21 in the joint.

[0040] The CFRP-bondant-CFRP structural joint was cured at a pressure of 0.1 MPa, with a heating rate of 1.0℃ / min, from room temperature to 120℃. After curing and holding at this temperature for 130 min, the temperature was then lowered from 120℃ to 50℃ at a rate of 1.0℃ / min to complete the curing process, thus producing CFRP bonded sample 3.

[0041] Example 3 A method for inducing secondary resin permeation based on laser CFRP interface pretreatment includes the following steps: A nanosecond pulsed fiber laser with a wavelength of 10.6 μm, a power of 150 W, a pulse frequency of 100 kHz, a scanning speed of 1000 mm / s, and a spot diameter of 100 μm is used to perform unidirectional parallel line scanning processing on the bonding position of the carbon fiber reinforced epoxy resin matrix composite 1. This forms a macroscopic flow channel. The resin layer in the channel is scanned once or multiple times to reach a predetermined resin removal thickness. After the resin 12 is completely removed and the surface of the carbon fiber 11 is exposed, a primary structure with a macroscopic flow channel is obtained. The depth of the completely removed resin 12 is 30% of the thickness of the carbon fiber reinforced epoxy resin matrix composite 1, the depth of the macroscopic flow channel is 100% of the resin removal depth, the width of the macroscopic flow channel is 500 μm, the period of the macroscopic flow channel is 500 μm, and the depth is 1 mm.

[0042] An ultrafast laser with a pulse width of 10 ps, ​​a wavelength of 600 nm, a power of 100 W, a pulse frequency of 5000 kHz, a scanning speed of 4000 mm / s, and a spot diameter of 40 μm was used to perform parallel path scanning on the surface of a macroscopic flow channel to form a secondary structure with a period of 1000 nm, consisting of nano-waves or micron-scale dendritic fractals. The periodic processing spacing of the nano-waves or micron-scale dendritic fractals in this secondary structure is 10 μm, resulting in a "primary + secondary" structure.

[0043] Loctite EA7000 050N WAERO resin binder 22 is evenly placed on the surface of the upper and lower spliced ​​secondary structure to obtain the CFRP-binder-CFRP structural joint 2, wherein the thickness of the Loctite EA7000 050N WAERO resin binder is 0.7mm. The structure in the CFRP-binder-CFRP structural joint 2 where the Loctite EA7000 050N WAERO resin binder 22 is not evenly placed is the CFRP matrix 21 in the joint.

[0044] The CFRP-bondant-CFRP structural joint was cured at a curing pressure of 0.3 MPa, with a heating rate of 3℃ / min from room temperature to 240℃. After curing and holding at this temperature for 150 min, the temperature was then lowered from 240℃ to 60℃ at a rate of 3℃ / min to complete the curing process, thus producing CFRP bonded sample 3.

[0045] Comparative Example 1 A CFRP interface preprocessing method includes the following steps: Loctite EA7000 050N WAERO resin binder 22 is evenly placed between the upper and lower CFRP substrate surfaces to be bonded, resulting in a CFRP-binder-CFRP structural joint 2, wherein the thickness of the Loctite EA7000 050N WAERO resin binder 22 is 0.15mm. The CFRP substrate 21 within the CFRP-binder-CFRP structural joint 2 is the part where the Loctite EA7000 050N WAERO resin binder 22 is not evenly placed.

[0046] The CFRP-bondant-CFRP structural joint was cured at a pressure of 0.05 MPa, with the temperature increased from room temperature to 178°C at a rate of 0.5°C / min. After curing and holding at this temperature for 120 min, the temperature was then decreased from 178°C to 70°C at a rate of 0.5°C / min to complete the curing process, thus producing a CFRP bonded sample.

[0047] CFRP bonded samples can be prepared in all of the above Examples 1 to 3. Now, the CFRP bonded sample 3 prepared in Example 1 and the CFRP bonded sample prepared in Comparative Example 1 are used for experimental verification.

[0048] (a) Mechanical properties Table 1 shows the tensile strength of the CFRP bonded samples prepared in Example 1 and Comparative Example 1. Comparative analysis revealed that the tensile strength of the CFRP bonded sample prepared in Example 1 was increased by 30% compared to Comparative Example 1, indicating enhanced interfacial mechanical and chemical bonding capabilities. After the resin binder is heated and melted, it flows into the processed microstructure, and upon cooling and solidification, forms a tenon-and-mortise structure, thereby enhancing the mechanical interfacial bonding force. Furthermore, the laser processing introduces polar functional groups such as hydroxyl (-OH), carboxyl (-COOH), and carbonyl (C=O) groups onto the material surface. These functional groups can form hydrogen bonds, esterification reactions, or covalent bonds with the -OH, -NH2, and -COOH groups in adhesives such as epoxy, phenolic, and polyurethane, thereby enhancing chemical bonding capabilities.

[0049] like Figure 4 As shown, the untreated sample joint in Comparative Example 1 fractured under a tensile force of 5000 N, while the laser-treated joint prepared in Example 1 fractured under a tensile force of 6500 N. The area of ​​the joints prepared in both Comparative Example 1 and Example 1 was 3 cm². 2 Using the formula force / area = tensile strength, the tensile strength of the former is 16.7 MPa, while the tensile strength after laser treatment is 21.2 MPa. This indicates that laser treatment enhances the interfacial mechanical bonding.

[0050] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for inducing secondary resin permeation based on laser CFRP interface pretreatment, characterized in that, Includes the following steps: CFRP matrix is ​​a thermosetting composite material made of epoxy resin and carbon fiber; A nanosecond pulsed fiber laser was used to perform grid scanning on the surface of the CFRP substrate to be bonded. The scanning interval was consistent with the diameter of the laser focusing spot. After scanning, the scanning interval and number of scans of the nanosecond pulsed fiber laser were changed according to the width and period of the required macroscopic flow channel to form the macroscopic flow channel. The parameters of the nanosecond pulsed fiber laser were: wavelength 355nm~10.6μm, power 20W~150W, pulse frequency 1kHz~100kHz, scanning speed 100mm / s~1000mm / s, and spot diameter 50μm~100μm. The resin layer within the macroscopic flow channel is completely removed by nanosecond pulsed fiber laser to expose the carbon fiber, forming a primary structure that provides a rapid and continuous macroscopic flow channel for the adhesive. The resin removal depth accounts for 10% to 30% of the total thickness of the CFRP matrix, the depth of the macroscopic flow channel is 50% to 100% of the resin removal depth, the width of the macroscopic flow channel is 100 μm to 500 μm, and the periodic spacing of the macroscopic flow channel is 200 μm to 500 μm. An ultrafast laser is used to scan the surface of the macroscopic flow channel of the primary structure. The ultrafast laser periodically processes the surface of the macroscopic flow channel using a parallel path with a processing interval of 5μm to 10μm to form a secondary structure with a period of 400nm to 1000nm, which is a nano-wave or micron-scale dendritic fractal. That is, a composite micro-nano structure is formed on the CFRP surface to be bonded. The secondary structure is used to drive the adhesive to penetrate the secondary structure through capillary force. The parameters of the ultrafast laser are: pulse width of 50fs to 10ps, wavelength of 180nm to 600nm, power of 1W to 100W, pulse frequency of 100kHz to 5000kHz, scanning speed of 1000mm / s to 4000mm / s, and spot diameter of 20μm to 40μm. The scanning angles of both nanosecond pulsed fiber lasers and ultrafast lasers are adjusted according to the layup direction of the CFRP matrix to avoid mechanical cutting of the carbon fibers. An epoxy resin binder with a thickness of 0.15 mm to 0.7 mm is evenly placed on the secondary structure surface at the interface between the upper and lower CFRP matrix layers to obtain a CFRP-epoxy resin binder-CFRP structural joint. The structural joint of CFRP-epoxy resin binder-CFRP is subjected to hot pressing curing treatment. The parameters for hot-press curing are as follows: curing heating rate is 0.5℃ / min~3℃ / min; curing holding time is 120min~150min; curing temperature is 120℃~240℃; curing pressure is 0.05MPa~0.3MPa; cooling rate is 0.5℃ / min~3℃ / min; cooling temperature is below 70℃.

2. The method of inducing secondary resin infusion by laser CFRP interfacial pretreatment according to claim 1, characterized in that, The thickness of the epoxy resin binder is 0.15mm to 0.5mm.

3. The method of inducing secondary resin infusion by laser CFRP interfacial pretreatment according to claim 1, characterized in that, The hot-press curing process includes: heating to 178°C at a curing rate of 0.5°C / min to 3°C / min, holding at that temperature for 120 min to 150 min, and then cooling to below 70°C at a cooling rate of 0.5°C / min to 3°C / min.

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