A surface pre-treatment-repair method for composite materials

Abstract

The present application relates to a kind of surface pretreatment-repairing method of composite material, belong to the technical field of composite material surface treatment, for solving the existing composite material bonding repair process The mechanical removal of easy to cause secondary damage to the surface of composite material, the interfacial bonding strength of repaired composite material is lower;Bonding repair process long curing time Problem.It includes: using ultraviolet laser scanning the damage site of composite material, remove the damage site of composite material;The composite material treated in step 1 is cleaned;Adhesive interface is activated using low-temperature plasma;Lay adhesive film, scrape flat;Then lay patch, scrape flat and compact, then package;Heat curing, curing stage is assisted by ultrasonic radiation;After heating and curing, the repaired area is polished.The interfacial tensile shear strength of the composite material repaired by the surface pretreatment-repairing method of composite material of the present application is significantly improved;And shorten the curing time.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite material surface repair, and particularly relates to a surface pretreatment-repair method of composite material. BACKGROUND

[0002] Advanced resin-based composite materials have many advantages such as high specific strength, high specific stiffness, strong designability, good anti-fatigue fracture performance, corrosion resistance, good dimensional stability, structural and functional integration, and easy large-area integral forming, and are rapidly increasing in application in the fields of spacecraft, aircraft, ships, high-speed trains, automobiles, and the like, and partially replace aluminum alloy, steel, and become one of the most rapidly developed advanced materials in equipment structural materials.

[0003] One of the main problems hindering the further application of advanced composite materials is the repair of composite material structure damage. Mechanical impact is one of the main forms of causing damage to composite materials. Poor impact resistance is an inherent deficiency of resin-based composite materials. When subjected to mechanical impact, metal materials can absorb energy through plastic deformation and elastic deformation, thereby avoiding the initiation and propagation of cracks. However, the interlaminar shear strength of resin-based composite materials is usually only tens of megapascals, which is much lower than the performance within the layer, and the composite material has poor ductility, so it is easy to form damage after being subjected to mechanical impact. The damage forms of composite materials usually include delamination, fiber fracture, damage, and hole penetration.

[0004] The composite material bonding repair process has advantages such as no new stress concentration, no significant increase in structure weight, good anti-fatigue performance after repair, and the like, and is the focus of research on composite material structure damage repair technology. At present, the traditional process method is mainly used in the repair of composite material damage and defects in aircraft and other equipment, that is, mechanical polishing processing and pretreatment are used, then a pre-preg is pasted and packaged by using the digging and patching method, and finally a composite material hot repair instrument is used for heating and curing. The bonding strength of the bonding repair interface directly affects the quality of the bonding repair. The existing composite material bonding repair process uses mechanical digging, which easily causes secondary damage to the surface of the composite material and causes certain damage to the strength after repair, and the interfacial bonding strength of the repaired composite material is low; and the curing time is long, and the repair efficiency is low. SUMMARY

[0005] In view of the above analysis, the present application provides a surface pretreatment-repair method of composite material, which can at least solve one of the following technical problems: (1) the mechanical digging of the existing composite material bonding repair process easily causes secondary damage to the surface of the composite material, causes certain damage to the strength after repair, and the interfacial bonding strength of the repaired composite material is low; (2) the curing time of the existing composite material bonding repair process is long.

[0006] To solve the above problems, the technical scheme adopted by the present application is as follows:

[0007] The present application provides a surface pretreatment-repairing method of composite material, comprising:

[0008] Step 1, scanning the damaged part of the composite material by using ultraviolet laser, and removing the damaged part of the composite material;

[0009] Step 2, cleaning the composite material after step 1;

[0010] Step 3, activating the bonding interface by using low-temperature plasma;

[0011] Step 4, laying the adhesive film and scraping it flat, then laying the patch according to the size of the damaged area, scraping it flat and compacting, and then packaging;

[0012] Step 5, heating and curing, and using ultrasonic radiation to assist curing in the curing stage;

[0013] Step 6, polishing the repaired area after heating and curing.

[0014] Further, it further comprises step 7, detecting by using ultrasonic nondestructive testing instrument to judge whether there is delamination or glue defect, if there is delamination or glue defect, repeating steps 1-6, if there is no delamination or glue defect, completing the repair work.

[0015] Further, in step 1, the wavelength of the ultraviolet laser is 355 nm.

[0016] Further, in step 1, the power of the ultraviolet laser is 10-15w, the spot diameter is 20μm, the pulse width is 10ps, and the scanning speed is 1500-2000mm / s.

[0017] Further, in step 2, the composite material is cleaned by using an ultrasonic cleaning machine.

[0018] Further, in step 3, the step of activating the bonding interface by using low-temperature plasma is: using a low-temperature plasma surface treatment equipment, the nozzle distance of the plasma gun to the workpiece is 5-8cm, and the spot moving speed is 3-5cm / s.

[0019] Further, in step 4, the adhesive film should be laid within 1min after plasma treatment.

[0020] Further, in step 4, the packaging step comprises: laying a release cloth, a heating blanket, an air-permeable felt and a vacuum bag successively above the patch.

[0021] Further, the step 5, before heating and curing, further comprises applying ultrasonic coupling agent on the flat position adjacent to the area to be repaired, placing the ultrasonic vibration head thereon, and adjusting to completely adhere.

[0022] Further, the step 5, the heating and curing step comprises: opening the composite material heat repair instrument for heating and curing, vacuumizing, when the temperature reaches the corresponding lowest viscosity holding platform, performing ultrasonic irradiation, and turning off the ultrasonic vibration switch after 5-10 min.

[0023] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0024] (1) In the surface pretreatment-repair method of the composite material of the present application, the damaged part of the composite material is removed by laser removal, and the ultraviolet laser does not cause damage to the surface of the composite material, so that the adhesive can directly contact the carbon fiber in the subsequent gluing process to improve the bonding effect.

[0025] (2) In the surface pretreatment-repair method of the composite material of the present application, the mechanical damage layer of the surface layer of the composite material is first removed by laser, which does not cause damage to the carbon fiber at the interface, and can not destroy the characteristics of the carbon fiber at the interface, such as fiber length and strength, to provide complete interface conditions for low-temperature plasma activation; then the low-temperature plasma activation adhesive interface is used, which can effectively improve the roughness of the adhesive surface, increase the surface activity, and increase the oxygen-containing active functional groups, so as to improve the proportion of chemical bonds of the adhesive interface, while ensuring the uniformity of the distribution of roughness, active functional groups, and chemical bond proportion, thereby better improving the interfacial bonding strength and the final repair effect of the repair matrix and the patch.

[0026] (3) In the surface pretreatment-repair method of the composite material of the present application, ultrasonic irradiation is used in the curing stage, which can break the bubbles in the liquid resin, generate high temperature and high pressure at the same time, homogenize the blending system, reduce the viscosity of the resin, and reduce the contact angle, so as to improve the resin and fiber infiltration performance, improve the bonding strength, and shorten the curing time (from the existing 150 min to 130 min).

[0027] (4) The interfacial tensile shear strength between the patch, the matrix, and the adhesive film of the composite material repaired by the method of the present application reaches about 37 Mpa, which is 40% higher than the existing strength of 26.3 Mpa of the single sandpaper polishing; and the uniformity of the interfacial shear strength between the patch, the matrix, and the adhesive film of the composite material is better, which greatly improves the repair quality.

[0028] The above technical solutions can be combined with each other in the present application to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent description, and some advantages will become apparent from the description, or will be understood by those skilled in the art through implementation of the present application. The purposes and other advantages of the present application can be achieved and obtained through the contents specifically indicated in the description and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification, illustrate embodiments of the application, and together with the description serve to explain the principles of the application.

[0030] Figure 1 Structure diagram of the composite material to be repaired;

[0031] Figure 2 Appearance after mechanical excavation of the damage site;

[0032] Figure 3 Interface appearance diagram after ultraviolet laser excavation;

[0033] Figure 4 Schematic diagram after encapsulation;

[0034] Figure 5 Schematic diagram of ultrasonic wave propagation during repair;

[0035] Figure 6 Structure diagram of the device for repairing the composite material.

[0036] Reference signs

[0037] 1-patch, 2-mother plate, 3-film, 4-area to be repaired, 5-release cloth, 6-heating blanket, 7-air-permeable felt, 8-vacuum bag, 9-vacuum nozzle, 10-vacuum gauge, 11-temperature measurement assembly, 12-computer display, 13-PLC control unit, 14-ultrasonic wave controller, 15-ultrasonic transducer, 16-vacuum pressure sensor, 17-vacuum pump, 18-heating controller, 19-vacuum joint. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present application will be specifically described below in combination with the drawings, wherein the drawings constitute a part of the present application, and are used to explain the principles of the present application together with the embodiments of the present application, and are not used to limit the scope of the present application.

[0039] At present, the damage of composite structure is mostly repaired by adhesive repair process, which includes patching and digging repair. Taking the digging repair as an example, the damaged part is first dug out, and then the adhesive film and the patch are sequentially attached for repair. The digging repair can well restore the aerodynamic shape of the component, basically does not produce repair stress, and does not exist load eccentricity, which is a commonly used repair method for composite structure repair. Figure 1 As shown in FIG. 1, the adhesive film 3 is located between the patch 1 and the parent plate 2 of the composite material, and the adhesive film 3 generally bears shear and transverse tensile and compressive load, and its failure mode is peeling failure and shear failure. The digging repair hopes to exert the bearing capacity of the parent plate 2, the adhesive film 3 and the patch 1, so that the overall performance of the repaired structure is restored to the greatest extent. In the repair process, the bonding strength between the parent plate 2, the adhesive film 3 and the patch 1 directly affects the overall digging repair effect. At present, the digging of the damaged part of the composite structure generally adopts a mechanical method to process the damaged part into a conical slope with a certain length-thickness ratio, and to a certain extent, the roughening of the adhesive surface is realized. This process is easy to cause secondary damage to the surface of the composite material, and also causes certain damage to the strength after repair. Figure 2 As shown in FIG. 2, the surface resin has been polished, the internal carbon fiber is exposed, and multiple fracture damages occur, and there are many resin debris particles on the surface. This is because in the process of mechanically removing the damaged part, due to the uncontrollability of external force, the internal carbon fiber is easily damaged while the surface resin is removed, and a large amount of resin debris is generated. These resin residues and damaged fibers will greatly affect the bonding repair strength.

[0040] The present application discloses a surface pretreatment-repair method of composite material, comprising: removing the damaged part of the composite material by laser; activating the adhesive interface by low-temperature plasma; and using ultrasonic irradiation to assist curing during the adhesive repair of the prepreg.

[0041] Specifically, the surface pretreatment-repair method of the composite material comprises:

[0042] Step 1, scanning the damaged part of the composite material by ultraviolet laser to remove the damaged part of the composite material;

[0043] Step 2, cleaning the composite material treated in step 1;

[0044] Step 3, activating the adhesive interface by low-temperature plasma;

[0045] Step 4, laying the adhesive film 3 and scraping it flat, then laying the patch 1 according to the size of the damaged area, scraping it flat and compacting, and then packaging;

[0046] Step 5, heating and curing, the curing stage is assisted by ultrasonic irradiation;

[0047] Step 6, polishing the repaired area after the completion of curing;

[0048] Step 7, detection by ultrasonic nondestructive testing instrument, and the repair work is completed.

[0049] Specifically, the composite material is a resin-based composite material.

[0050] Specifically, in step 1, as shown in the figure, the damaged part is excavated into a circular wedge or a circular stepped blind hole. Figure 1 The angle is controlled to be about 3-6°.

[0051] Specifically, since the ultraviolet laser has the characteristics of selective ablation, it can effectively remove the damaged part of the surface layer of the composite material and expose the internal carbon fiber. Figure 3 As shown in the figure, the interface morphology after the ultraviolet laser removes the damaged part of the surface layer of the composite material.

[0052] Specifically, in step 1, the wavelength of the ultraviolet laser is 355nm.

[0053] Specifically, in step 1, the power of the ultraviolet laser is 10-15w, the spot diameter is 20μm, the pulse width is 10ps, and the scanning speed is 1500-2000mm / s.

[0054] Specifically, in step 2, the composite material can be cleaned by an ultrasonic cleaning machine to remove debris and oil stains adsorbed on the surface of the composite material.

[0055] Specifically, in step 2, considering that too long cleaning time wastes time and energy, and too short cleaning time has poor cleaning effect, the cleaning time is controlled to be 10-20min.

[0056] Specifically, in the step 3, the step of activating the bonding interface by low-temperature plasma is as follows: using an open low-temperature plasma surface treatment device, the power is 30 W, the nozzle of the plasma gun is 5-8 cm away from the workpiece, the light spot moving speed is 3-5 cm / s, and scanning is 1-2 times.

[0057] Specifically, in the step 3, the nozzle of the plasma gun is 5-8 cm away from the workpiece, the power is 30 W, the light spot moving speed is 3-5 cm / s, and scanning is 1-2 times, considering that the activation effect is weakened if the distance between the nozzle of the plasma gun and the workpiece is too large, and there is a possibility of surface burning if the distance is too small.

[0058] Specifically, in the step 4, the activated layer after low-temperature plasma treatment is easy to adsorb moisture in the air and be oxidized to reduce activity, so it is necessary to lay the adhesive film as soon as possible within 1 min.

[0059] Specifically, in the step 4, as shown in the figure, Figure 4 the packaging step includes laying a release cloth 5, a heating blanket 6, an air-permeable felt 7, and a vacuum bag 8 in sequence above the patch 1.

[0060] Specifically, in the step 5, before heating and curing, an ultrasonic coupling agent is applied to a flat position near the to-be-repaired area 4 (i.e., the damaged area), and an ultrasonic vibration head is placed thereon and adjusted to completely adhere. Specifically, the position of applying the ultrasonic coupling agent is less than 0.5 mm away from the edge of the to-be-repaired area. For example, the position of applying the ultrasonic coupling agent is 0 mm away from the edge of the to-be-repaired area.

[0061] Specifically, in the step 5, when the to-be-repaired area is large, an ultrasonic vibration head can be placed at a diagonal position of the original ultrasonic vibration head to ensure uniform ultrasonic irradiation.

[0062] Specifically, in the step 5, the principle of using ultrasonic irradiation to assist in repairing the composite material is that ultrasonic cavitation effect can produce local high temperature, high pressure, and strong shock waves and micro-jets, so that the ultrasonic wave has multiple effects of strong dispersion, crushing, and activation. When the ultrasonic irradiation acts on the liquid resin, the bubbles are broken, high temperature and high pressure are generated, the blending system is homogenized, the resin viscosity is reduced, the contact angle is reduced, the resin infiltration performance is improved, the bonding strength is improved, and the curing time is shortened.

[0063] It should be noted that in the step 5, the device used for heating and curing is a composite material repair instrument, and the principle of setting the process parameters for heating and curing is as follows: the heating and curing process is formulated according to the type of the resin of the patch used. The temperature corresponding to the lowest point of the viscosity-temperature curve is set as the holding platform temperature, and the holding platform time is usually 5-10 min, which is consistent with the ultrasonic irradiation time.

[0064] It should be noted that in the above step 5, the heating and curing step includes: opening the heating switch of the composite hot repair instrument for heating and curing, opening the vacuum pump for vacuumizing, opening the ultrasonic vibration switch when the temperature reaches the corresponding lowest viscosity holding platform, and performing ultrasonic irradiation, and closing the ultrasonic vibration switch after 5-10 minutes.

[0065] It should be noted that in the above step 5, the ultrasonic vibration head is a longitudinal wave probe. The probe power is 100W, and the frequency is 28KHz.

[0066] It should be noted that in the above step 6, sandpaper with a mesh size of ≤120 is used for polishing and polishing, and the purpose of polishing and polishing is to remove excess tumor and make the edge of the repair area smooth and transition.

[0067] It should be noted that in the above step 7, the ultrasonic nondestructive testing instrument is used for detection to determine whether there are delamination, lack of glue and other defects. If there are delamination or lack of glue and other defects, steps 1-6 need to be repeated. If there are no delamination, lack of glue and other defects, the repair work is completed.

[0068] Compared with the prior art, in the surface pretreatment-repair method of the composite material of the present application, the damaged part of the composite material is removed by laser removal method, the ultraviolet laser does not cause damage to the surface of the composite material, so that the adhesive can directly contact the carbon fiber in the subsequent gluing process to improve the bonding effect; the low-temperature plasma is used to activate the gluing interface, which can effectively improve the roughness of the gluing surface, increase the surface activity and increase the oxygen-containing active functional groups, so as to increase the proportion of chemical bonds of the gluing interface and improve the interface bonding strength and the final repair effect of the repair matrix and the patch; ultrasonic irradiation is used in the curing stage, which can break the bubbles in the liquid resin and generate high temperature and high pressure at the same time, so as to homogenize the blending system, reduce the resin viscosity and contact angle, improve the resin and fiber infiltration performance, improve the bonding strength and shorten the curing time (from the existing 150min to 130min). The interface shear strength between the patch, the matrix and the adhesive film of the composite material repaired by the method of the present application reaches 37Mpa, which is higher than the existing strength of 26.3Mpa by 40% or more; and the dispersion degree of the interface shear strength between the patch, the matrix and the adhesive film of the composite material repaired by the method of the present application is reduced, and the dispersion coefficient is reduced by 66%.

[0069] The application further provides a surface pre-treatment-repair device for a composite material, comprising a laser, a low-temperature plasma surface treatment device, an ultrasonic device and a composite material thermal repair instrument; the laser can emit laser light for removing a damaged part of the composite material; the low-temperature plasma surface treatment device is used for spraying plasma to the surface of the composite material to realize surface pre-treatment; the region to be repaired of the composite material is located in an ultrasonic irradiation region of the ultrasonic device, and the ultrasonic device provides ultrasonic irradiation for the region to be repaired of the composite material during repair by the composite material thermal repair instrument.

[0070] Specifically, the laser can emit ultraviolet laser light, and the wavelength of the ultraviolet laser light is 355 nm. After the damaged region of the composite material is removed by mechanical digging, the interface after digging is scanned multiple times by the ultraviolet laser light to remove a mechanical damage layer generated due to mechanical digging.

[0071] Specifically, the low-temperature plasma surface treatment device can activate the bonding interface by plasma after laser scanning.

[0072] Specifically, the ultrasonic device comprises an ultrasonic controller 14 and an ultrasonic transducer 15.

[0073] Specifically, considering that the region to be repaired of the composite material is large, the ultrasonic wave application of a single ultrasonic transducer 15 can be non-uniform, therefore, the number of the ultrasonic transducers 15 is controlled to be multiple, for example, 2.

[0074] Specifically, the ultrasonic transducer 15 adopts a longitudinal wave probe, the probe power is 100 W, and the frequency is 28 KHz.

[0075] Specifically, the composite material thermal repair instrument comprises a display unit, a control unit and a vacuum pumping device; the control unit comprises a temperature control unit, a vacuum control unit and an ultrasonic control unit.

[0076] Specifically, the temperature control unit comprises a temperature measuring assembly 11 and a heating controller 18.

[0077] Specifically, the vacuum control unit comprises a vacuum pressure sensor 16.

[0078] Specifically, the display unit can be a computer display 12.

[0079] Specifically, the control unit can be a PLC control unit 13, and the PLC control unit 13 comprises the temperature measuring assembly 11, the heating controller 18 and the vacuum pressure sensor 16.

[0080] Specifically, the vacuumizing device comprises a vacuum nozzle 9, a vacuum gauge 10, a vacuum pump 17, a vacuum bag 8 and a vacuumizing hose and a vacuumizing connector 19; the vacuum bag 8 is in sealed communication with the vacuumizing connector 19, and the vacuumizing connector 19 is connected with the vacuum pump 17 through the vacuumizing hose; the PLC control unit 13 can realize the following functions: heating temperature and heating time control, vacuumizing and vacuum degree control, ultrasonic wave application and time control.

[0081] Specifically, the PLC control unit 13 guides the vacuumizing device to vacuumize and control the vacuum degree according to the detection data of the vacuum pressure sensor 16; and the PLC control unit 13 guides the heating controller 18 to work according to the detection data of the temperature measuring assembly 11.

[0082] Specifically, the ultrasonic wave controller 14 is connected with the ultrasonic control unit of the PLC control unit 13, and the ultrasonic wave controller 14 controls the ultrasonic wave application and time according to the data instruction of the ultrasonic control unit.

[0083] Specifically, the PLC control unit 13 further comprises a current sensor.

[0084] Specifically, the composite material thermal repair instrument further comprises a release cloth 5, a heating blanket 6 and a breather felt 7, which are used for packaging the area to be repaired of the composite material.

[0085] Specifically, the temperature measuring assembly 11 comprises a plurality of thermocouples.

[0086] Compared with the prior art, the composite material surface pretreatment-repair device provided by the present application has the same beneficial effects as the composite material surface pretreatment-repair method, which will not be repeated here.

[0087] Embodiment 1

[0088] The present embodiment provides a composite material surface pretreatment-repair method, which comprises the following steps:

[0089] Step 1: scanning the damaged part of the composite material by using ultraviolet laser to remove the damaged part of the composite material; specifically, the damaged part is excavated into a circular wedge or a circular stepped blind hole; wherein the wavelength of the ultraviolet laser is 355 nm, the power is 10 w, the spot diameter is 20 μm, the pulse width is 10 ps, and the scanning speed is 1500 mm / s.

[0090] Step 2: cleaning the composite material treated in step 1 by using an ultrasonic cleaning machine to remove the debris and oil stains adsorbed on the surface of the composite material; specifically, industrial ethanol is used as the medium during cleaning;

[0091] Step 3, activate the bonding interface by low-temperature plasma: use an open low-temperature plasma surface treatment equipment, power 30W, nozzle distance of the plasma gun to the workpiece 6cm, light spot moving speed 4cm / s, scan 2 times;

[0092] Step 4, lay the adhesive film 3 on the bonding interface treated in step 3, and scrape it flat; then lay the patch 1 according to the size of the damage area, scrape it flat, compact it, and then package; the packaging steps include: lay the release cloth 5, heating blanket 6, air-permeable felt 7, and vacuum bag 8 in sequence above the patch 1;

[0093] Step 5, heat and cure, and use ultrasonic radiation to assist curing; the heating and curing steps include: turn on the heating switch of the composite hot repair instrument to heat and cure, turn on the vacuum pump to vacuumize, when the temperature reaches the corresponding lowest viscosity holding platform, turn on the ultrasonic vibration switch to perform ultrasonic irradiation, and turn off the ultrasonic vibration switch after 5-10 minutes;

[0094] Step 6, after the heating and curing are completed, polish the repaired area;

[0095] Step 7, use the ultrasonic nondestructive testing instrument to detect, and if there is no delamination or lack of adhesive, the repair work is completed.

[0096] Example 2

[0097] The present embodiment provides a surface pretreatment-repair device for composite materials implementing the above method, as shown in Figure 6 the figure, including a laser, a low-temperature plasma surface treatment equipment, an ultrasonic device, and a composite hot repair instrument, the ultrasonic device includes an ultrasonic controller 14 and an ultrasonic transducer 15, and the ultrasonic device can provide ultrasonic irradiation when the composite hot repair instrument repairs the to-be-repaired area of the composite material.

[0098] Specifically, the above-mentioned composite hot repair instrument includes a computer display 12, a PLC control unit 13, and a vacuumizing device, the PLC control unit 13 includes a temperature measuring assembly 11, a heating controller 18, and a vacuum pressure sensor 16; the vacuumizing device includes a vacuum nozzle 9, a vacuum gauge 10, a vacuum pump 17, a vacuum bag 8, and a vacuumizing hose and vacuumizing connector 19; the vacuum bag 8 is connected and sealed with the vacuumizing connector 19, and the vacuumizing connector 19 is connected with the vacuum pump 17 through the vacuumizing hose; the PLC control unit 13 can realize the following functions: heating temperature and heating time control; vacuumizing and vacuum degree control; ultrasonic wave application and time control.

[0099] Specifically, the PLC control unit 13 guides the vacuumizing device to vacuumize and control the vacuum degree according to the detection data of the vacuum pressure sensor 16; and the PLC control unit 13 guides the heating controller 18 to work according to the detection data of the temperature measuring assembly 11.

[0100] Specifically, the ultrasonic controller 14 is connected to the PLC control unit 13, and the ultrasonic controller 14 applies ultrasonic waves and controls the time according to the data instructions of the PLC control unit 13.

[0101] Specifically, the aforementioned PLC control unit 13 also includes a current sensor.

[0102] Specifically, the aforementioned composite material heat repair device also includes a release cloth 5, a heating blanket 6, and a breathable felt 7, which are used to encapsulate the area of ​​the composite material to be repaired.

[0103] Specifically, the temperature measuring component 11 includes multiple thermocouples.

[0104] Specifically, there are two ultrasonic transducers 15.

[0105] Specifically, the ultrasonic transducer 15 mentioned above uses a longitudinal wave probe with a power of 100W and a frequency of 28KHz.

[0106] Specifically, the aforementioned computer monitor 12 is an industrial all-in-one computer.

[0107] Specifically, the aforementioned laser is capable of emitting ultraviolet laser light.

[0108] The aforementioned low-temperature plasma surface treatment equipment is used to activate the interface of composite materials after the damaged areas have been removed.

[0109] The inventors of this invention conducted in-depth research and experiments on various repair methods, but none of them achieved the same repair results as the methods described above. The inventors present several of their researched repair methods as comparative examples, as follows:

[0110] Comparative Example 1

[0111] This comparative example provides a method for repairing composite materials, including:

[0112] Step 1: Remove the damaged parts of the composite material using mechanical excavation.

[0113] Step 2: Use an ultrasonic cleaner to clean the composite material after the treatment in Step 1 to remove debris and oil adsorbed on the surface of the composite material.

[0114] Step 3: Apply adhesive film 3 to the adhesive interface treated in step 2 and smooth it; then apply patch 1 according to the size of the damaged area, smooth and compact it, and then seal it; the sealing steps include: laying release cloth 5, heating blanket 6, breathable felt 7, and vacuum bag 8 on top of patch 1 in sequence.

[0115] Step 4: Heating and curing. Ultrasonic radiation was not used to assist in curing during the curing stage.

[0116] Step 5, after the completion of the heating and curing, the repair area is polished, and an ultrasonic non-destructive testing instrument is used for testing. If there is no delamination or lack of glue, the repair work is completed.

[0117] Comparative Example 2

[0118] The comparative example provides a repair method of a composite material, comprising:

[0119] Step 1, the damaged part of the composite material is removed by using ultraviolet laser scanning. Specifically, the damaged part is excavated into a circular wedge or a circular stepped blind hole. The wavelength of the ultraviolet laser is 355 nm, the power is 10 w, the spot diameter is 20 μm, the pulse width is 10 ps, and the scanning speed is 1500 mm / s.

[0120] Step 2, the composite material treated in step 1 is cleaned by using an ultrasonic cleaning machine to remove debris and oil stains adsorbed on the surface of the composite material. Specifically, industrial ethanol is used as the medium during cleaning.

[0121] Step 3, the adhesive interface is activated by using low-temperature plasma. An open low-temperature plasma surface treatment equipment is used, the power is 30 W, the nozzle of the plasma gun is 6 cm away from the workpiece, the spot moving speed is 4 cm / s, and the scanning is 2 times.

[0122] Step 4, the adhesive film 3 is laid on the adhesive interface treated in step 3 and is scraped flat. Then, the patch 1 is laid according to the size of the damaged area, and is scraped, compacted, and then packaged. The packaging steps include: sequentially laying release cloth 5, heating blanket 6, air-permeable felt 7, and vacuum bag 8 above the patch 1.

[0123] Step 5, heating and curing, and the ultrasonic radiation is not used for auxiliary curing during the curing stage.

[0124] Step 6, after the completion of the heating and curing, the repair area is polished.

[0125] Step 7, an ultrasonic non-destructive testing instrument is used for testing. If there is no delamination or lack of glue, the repair work is completed.

[0126] Comparative Example 3

[0127] The comparative example provides a repair method of a composite material, comprising:

[0128] Step 1, the damaged part of the composite material is removed by using ultraviolet laser scanning. Specifically, the damaged part is excavated into a circular wedge or a circular stepped blind hole. The wavelength of the ultraviolet laser is 355 nm, the power is 10 w, the spot diameter is 20 μm, the pulse width is 10 ps, and the scanning speed is 1500 mm / s.

[0129] Step 2, the composite material treated in step 1 is cleaned by using an ultrasonic cleaning machine to remove the debris and oil stains adsorbed on the surface of the composite material; specifically, industrial ethanol is used as the medium during cleaning;

[0130] Step 3, the adhesive interface treated in step 2 is laid with a film 3, and then the patch 1 is laid according to the size of the damage area, and then the patch 1 is flattened, compacted, and then packaged; the packaging step includes sequentially laying a release cloth 5, a heating blanket 6, a breather felt 7, and a vacuum bag 8 above the patch 1;

[0131] Step 4, heating and curing, and the curing stage is assisted by ultrasonic radiation; the heating and curing step includes turning on the heating switch of the composite material repair instrument to heat and cure, turning on the vacuum switch to vacuumize, turning on the ultrasonic vibration switch when the temperature reaches the corresponding lowest viscosity holding platform, and performing ultrasonic irradiation for 5-10 minutes, and then turning off the ultrasonic vibration switch;

[0132] Step 5, after the heating and curing is completed, the repaired area is polished;

[0133] Step 6, using an ultrasonic nondestructive testing instrument for detection, there is no delamination, lack of glue, and other defects, and the repair work is completed.

[0134] Specifically, in example 1 and comparative examples 1-3, the main component of the resin of the mother plate material of the composite material is a low-temperature curing epoxy resin, and the reinforcing body is carbon fiber; the material of the patch is an epoxy-based carbon fiber prepreg. The film is an epoxy resin type film.

[0135] The tensile shear strength of the patch and the mother plate under the adhesion of the film of example 1 and comparative examples 1-3 is detected, the average value of the interfacial shear strength of example 1 is 37Mpa, and the dispersion degree of the interfacial shear strength value between the patch, the mother plate, and the film of the composite material is low, which is 0.137; the average value of the interfacial shear strength of comparative example 1 is 26.3Mpa, and the dispersion degree of the interfacial shear strength value between the patch, the mother plate, and the film of the composite material is 0.228; the average value of the interfacial shear strength of comparative example 2 is 35.2Mpa, and the interfacial shear strength of the composite material is slightly lower than that of example 1; the average value of the interfacial shear strength of comparative example 3 is 30.5Mpa, and the interfacial shear strength of the composite material is lower than that of example 1; it can be seen that the method of the present application can significantly improve the shear strength of the patch and the mother plate under the adhesion of the film, and the uniformity of the interfacial shear strength between the patch, the mother plate, and the film of the composite material is better, which greatly improves the repair quality.

[0136] The curing time of Example 1 is about 130 min; the curing time of Comparative Example 1 is about 150 min, the curing time of Comparative Example 2 is about 150 min, and the curing time of Comparative Example 3 is about 140 min. The method of the present application can shorten the curing time and improve the repair efficiency.

[0137] The above description is merely preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A surface pretreatment-repair method for composite materials, characterized in that, The surface pretreatment-repair method for the composite material includes: Step 1: Use ultraviolet laser to scan the damaged areas of the composite material and remove the damaged areas. Step 2: Clean the composite material after the treatment in Step 1; Step 3: Activate the adhesive interface using low-temperature plasma; Step 4: Apply the adhesive film and smooth it out; then apply the patch according to the size of the damaged area, smooth and compact it, and then seal it. Step 5: Heat curing, with ultrasonic radiation used for assisted curing during the curing stage; Step 6: After heat curing is complete, polish the repaired area. In step 1, the wavelength of the ultraviolet laser is 355nm, the power of the ultraviolet laser is 10-15W, the spot diameter is 20μm, the pulse width is 10ps, and the scanning speed is 1500-2000mm / s. The ultraviolet laser does not damage the carbon fiber at the interface, so that the adhesive can directly contact the carbon fiber in the subsequent bonding process to improve the bonding effect. In step 2, the cleaning time is controlled to be 10-20 minutes; In step 3, the step of activating the adhesive interface with low-temperature plasma is as follows: a low-temperature plasma surface treatment device is used, the distance between the plasma gun nozzle and the workpiece is 5-8cm, and the spot movement speed is 3-5cm / s. In step 4, the adhesive film should be applied within 1 minute after plasma treatment. In step 5, before heating and curing, an ultrasonic coupling agent is applied to a flat area adjacent to the area to be repaired, and the ultrasonic vibrating head is placed on it and adjusted to be completely in contact; the distance between the applied ultrasonic coupling agent and the edge of the area to be repaired is less than 0.5 mm. In step 5, the heating and curing step includes: turning on the composite material heat repair instrument for heating and curing, drawing a vacuum, and when the temperature reaches the insulation platform with the lowest corresponding viscosity, performing ultrasonic irradiation, and turning off the ultrasonic vibration switch after 5 to 10 minutes. The coefficient of variation of the interfacial shear strength values ​​between the patch, base plate, and adhesive film of the repaired composite material was reduced by 66%.

2. The surface pretreatment-repair method for composite materials according to claim 1, characterized in that, The procedure also includes step 7, which involves using an ultrasonic non-destructive testing instrument to determine whether there are any delamination or missing adhesive defects. If there are delamination or missing adhesive defects, steps 1-6 are repeated. If there are no delamination or missing adhesive defects, the repair work is completed.

3. The surface pretreatment-repair method for composite materials according to claim 1, characterized in that, In step 2, an ultrasonic cleaner is used to clean the composite material.

4. The surface pretreatment-repair method for composite materials according to claim 1, characterized in that, In step 3, the step of activating the adhesive interface with low-temperature plasma is as follows: a low-temperature plasma surface treatment device is used, the distance between the plasma gun nozzle and the workpiece is 6-8 cm, and the spot movement speed is 4-5 cm / s.

5. The surface pretreatment-repair method for composite materials according to claim 1, characterized in that, In step 4, the encapsulation step includes: sequentially covering the patch with a release cloth, a heating blanket, a breathable felt, and a vacuum bag.

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