A Method for Interface Modification of Fiber Metal Laminates and Its Application

Abstract

A method for interfacial modification of a fiber metal laminate and its application. The present invention belongs to the field of composite material preparation. The purpose of the present invention is to solve the technical problems of low interlayer bonding strength of existing fiber metal laminates and limited effects of existing methods for improving interfacial strength. The present invention first performs sandblasting on the metal surface, then immerses it in an ethanol solution of rare earth metal salt, sets a resin film between the metal and the prepreg after drying, and then performs hot pressing and molding to modify the interface. At the same time, through the design of the laminate structure and process control, a fiber metal laminate with both high interfacial strength and mechanical properties is prepared, with excellent comprehensive performance, meeting the material selection requirements for the skin of high-speed aircraft, and can be applied to the aerospace field.

Description

Technical Field

[0001] The present invention belongs to the field of composite material preparation, and particularly relates to a method for interfacial modification of a fiber metal laminate and its application. Background Art

[0002] A fiber metal laminate is an interlayer hybrid composite material prepared by alternately laminating a fiber-reinforced resin matrix composite material and a thin metal plate. The fiber metal laminate not only has the advantages of low density, high specific strength, and specific stiffness of the resin matrix composite material, but also makes up for the disadvantages of low fracture toughness, poor impact resistance, and low residual strength of the resin matrix composite material through the combination with the thin metal plate. At present, fiber metal laminates have been widely used in fields such as marine and aerospace.

[0003] Compared with a glass fiber-reinforced aluminum alloy laminate, the fourth-generation graphite / carbon fiber-reinforced titanium alloy laminate better maintains its mechanical properties at high temperatures (such as 250 °C) to meet the requirements for the material selection of the skin of high-speed aircraft. The graphite / carbon fiber-reinforced titanium alloy laminate has currently become one of the promising candidate materials for future applications in high-speed aircraft.

[0004] Although the fiber metal laminate has a series of advantages, due to the large difference in thermophysical properties between the metal and the resin, it is difficult to generate strong bonding at the interface, which will inevitably affect the load transfer efficiency between the metal and the fiber, as well as the failure mode and overall performance of the fiber metal laminate, restricting its application.

[0005] Currently, the main problem faced in the interfacial modification of fiber metal laminates is the large difference in physical and chemical properties between the metal and the resin, making it difficult to generate strong bonding between the interfaces. In the research on this system, most are to achieve mechanical meshing by increasing the surface roughness of the metal and using the resin itself as an adhesive. Or an adhesive is added between the metal and the fiber-reinforced resin matrix composite material, and then compounded by hot pressing. However, the improvement of the interfacial bonding strength by the above methods is still limited and cannot meet the requirements of the marine and aerospace fields. Summary of the Invention

[0006] The purpose of the present invention is to solve the technical problems of low interlayer bonding strength of existing fiber metal laminates and limited effectiveness of existing methods for improving interfacial strength, and to provide a method for interfacial modification of a fiber metal laminate and its application.

[0007] One of the purposes of the present invention is to provide a method for interfacial modification of a fiber metal laminate, and the method for interfacial modification of the fiber metal laminate includes the following process:

[0008] First, sandblast the metal surface, then soak it with an ethanol solution of rare earth metal salt, set a resin film between the metal and the prepreg after drying, and then perform hot pressing to form.

[0009] Further define that the sandblasting parameters are as follows: the spraying distance is 80 - 180 mm, the spraying pressure is 0.1 - 0.5 MPa, and the spraying time is 15 - 30 s.

[0010] Further define that the corundum sand used for sandblasting is 40 - 60 mesh.

[0011] Further define that the concentration of the ethanol solution of rare earth metal salt is 0.1 - 1 wt%.

[0012] Further define that the rare earth metal salt is selected from chlorides of rare earth elements.

[0013] Further define that the soaking time is 1 - 3 h.

[0014] Further define that the resin film is a PEEK film.

[0015] The second object of the present invention is to provide a preparation method of a fiber metal laminate with both high interfacial strength and mechanical properties. The preparation method of the fiber metal laminate is carried out according to the following steps:

[0016] Lay the metal after soaking and the prepreg CFRTP in the unidirectional ply structure of [M / 03 / M / 03 / M], and laminate a PEEK film between each layer of metal and prepreg CFRTP. Subsequently, through hot pressing, a fiber metal laminate with both high interfacial strength and mechanical properties is obtained.

[0017] Further define that the hot pressing process is as follows: start from room temperature and heat to 360 - 400 °C at a speed of 5 - 10 °C / min, then hold for 25 - 45 min. Subsequently, first cool down to 280 - 320 °C and hold for 25 - 45 min, then continue to cool down to 140 - 180 °C and hold for 25 - 45 min. Finally, cool down to room temperature, and the speed during the cooling process is always maintained at 1 - 10 °C / min. The pressure is maintained at 3 - 6 MPa throughout the process.

[0018] Wherein in [M / 03 / M / 03 / M], M represents metal, 03 represents that the laying angle of the prepreg is 0°, and the laying number of layers is 3 layers.

[0019] The third object of the present invention is to provide a fiber metal laminate prepared by the above method.

[0020] Further define that the interfacial shear strength of the fiber metal laminate is ≥27 MPa, the bending strength is ≥1460 MPa, and the interlaminar shear strength is ≥59 MPa.

[0021] A fourth object of the present invention is to provide an application of a fiber metal laminate prepared by the above method, and the fiber metal laminate is applied to the aerospace field.

[0022] The remarkable effects of the present invention compared with the prior art are as follows:

[0023] (1) The present invention proposes an interface modification method for a fiber metal laminate. First, an irregular flower cluster-like curled structure is constructed on the metal surface by sandblasting. The sharp-edged peaks and valleys are used to improve the mechanical meshing strength between the metal and the resin. At the same time, chemical bonding is effectively utilized to improve the wetting performance of the resin matrix in the prepreg on the metal surface, thereby effectively improving the bonding strength between the metal and the resin in the fiber metal laminate.

[0024] (2) The present invention also proposes a preparation method for a fiber metal laminate with both high interface strength and mechanical properties. Through the design of the laminate structure and process regulation, the obtained fiber metal laminate has a shear strength ≥ 27 MPa, a bending strength ≥ 1460 MPa, and an interlaminar shear strength ≥ 59 MPa. Its comprehensive performance is excellent, meeting the material selection requirements for the skin of high-speed aircraft, and can be applied to the aerospace field. Description of the Drawings

[0025] Figure 1 It is the SEM image of the surface morphology of S-Ti after sandblasting in the example;

[0026] Figure 2 is the XPS characterization diagram of the surface of S-RE-Ti after modification in the example; among them, a-Ce 3d spectrum, b-Cl 2p spectrum, c-Ti 2p spectrum, d-O 1s spectrum, e-XPS elemental spectrum;

[0027] Figure 3 It is the comparison diagram of the apparent contact angles of deionized water and diiodomethane on the surface of TA2 titanium alloy plates before and after modification in the example;

[0028] Figure 4 It is the comparison diagram of the interfacial bonding strength between the titanium alloy plate and the resin matrix in the fiber metal laminates prepared in the examples and comparative examples of the present invention;

[0029] Figure 5 It is the test comparison diagram of the bending strength and interlaminar shear strength of the fiber metal laminates prepared in the examples and comparative examples of the present invention. Detailed Embodiments

[0030] To make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used, unless otherwise specified, are all conventional materials, reagents, methods and instruments in this field, and those skilled in the art can obtain them through commercial channels.

[0032] The terms "comprising", "including", "having", "containing" or any other variation thereof used in the following embodiments are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device containing the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article or device.

[0033] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value are specifically disclosed, regardless of whether the ranges are separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range. In the specification and claims of this application, range limitations can be combined and / or interchanged, and if not otherwise stated, these ranges include all sub-ranges subsumed therein.

[0034] The indefinite articles "a" and "an" before the elements or components of the present invention do not limit the quantity requirements (i.e., the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted to include one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0035] Example:

[0036] The preparation method of the fiber metal laminate with both high interfacial strength and mechanical properties in this embodiment is carried out according to the following steps:

[0037] S1:

[0038] First, the TA2 titanium alloy plate is immersed in an acetone solution at 30°C and ultrasonically cleaned for 30 minutes to remove the grease on the surface. After that, it is cleaned with deionized water and dried for standby.

[0039] Then, corundum sand with a size of 40 - 60 mesh was used to sandblast the surface of the aforementioned TA2 titanium alloy plate. The spraying distance was 110 mm, the spraying pressure was 0.2 MPa, and the spraying time was 20 s. The obtained product was denoted as S-Ti;

[0040] S2:

[0041] First, an ethanol solution of CeCl3 with a concentration of 0.5 wt% was prepared;

[0042] Then, the TA2 titanium alloy plate after sandblasting in S1 was soaked with the above solution. After soaking for 2 h, the surface of the TA2 titanium alloy plate was rinsed with the ethanol solution to remove the rare earth that had not been deposited on the surface, and then it was directly dried in an oven at 80 °C, denoted as S-RE-Ti;

[0043] S3:

[0044] First, the TA2 titanium alloy plate after soaking in S2 and the prepreg CFRTP (Jiangsu Junhua Special Engineering Plastic Products Co., Ltd.) were laid according to the unidirectional ply structure of [M / 03 / M / 03 / M]. Among them, M in [M / 03 / M / 03 / M] represents metal, 03 represents that the laying angle of the prepreg is 0°, the number of laying layers is 3 layers, and a PEEK film was laminated between each layer of TA2 titanium alloy plate and prepreg CFRTP;

[0045] Subsequently, hot pressing was carried out. The hot pressing process was as follows: starting from room temperature, it was heated to 390 °C at a rate of 10 °C / min and then held for 30 min. Subsequently, it was first cooled to 300 °C and held for 30 min, then continued to be cooled to 170 °C and held for 30 min, and finally cooled to room temperature. The cooling rate during the cooling process was always maintained at 1 °C / min, and the pressure was maintained at 5 MPa throughout the process to obtain a fiber metal laminate.

[0046] First, the surface morphology of S-RE-Ti obtained in S2 was analyzed, and the results were as Figure 1 shown. From Figure 1 it can be seen that the rare earth-modified titanium alloy plate after sandblasting presented irregular flower cluster-like curls, showing a macroscopic hierarchy. These peaks and valleys with obvious sharp edges greatly increased the surface area of the metal and improved the ability of PEEK to embed into the titanium plate surface and generate mechanical meshing.

[0047] To verify that rare earth elements were successfully introduced onto the surface of the titanium alloy, XPS analysis was performed on the S-RE-Ti surface obtained in S2, and the elemental spectrogram obtained is shown in Figure 2. As can be seen from Figure 2, Ce in the +3 valence form and Cl in the -1 valence form were detected on the surface of the modified TA2 titanium alloy plate. Metal oxides appeared in the O1s spectrogram, and combined with the Ti2p spectrogram, it was determined that the oxide was only naturally oxidized TiO2 at this time, proving that rare earth elements were successfully introduced onto the titanium plate surface.

[0048] The apparent contact angles of deionized water and diiodomethane on the surface of the TA2 titanium alloy plate before and after S2 modification were measured, and the results are as Figure 3 shown. As Figure 3 can be seen, the apparent contact angle of S-RE-Ti after rare earth modification was significantly lower than that of S-Ti. At the same time, based on the apparent contact angle results, the surface energy of the TA2 titanium alloy plate was calculated. The results showed that the total surface energy, surface energy polar component, and surface energy non-polar component after modification were 51.2, 7.08, and 44.22 mJ / m 2 , respectively. This indicates that the wetting performance of the TA2 titanium alloy plate after rare earth modification was significantly improved, which is beneficial to the wetting behavior of the resin on the titanium plate surface.

[0049] Comparative example: The difference between this comparative example and the example is that S2 was omitted; the specific process is as follows:

[0050] S1:

[0051] First, the TA2 titanium alloy plate was immersed in an acetone solution at 30 °C and ultrasonically cleaned for 30 min to remove the grease on the surface. After that, it was cleaned with deionized water and dried for later use.

[0052] Then, corundum sand with a size of 40 - 60 mesh was used to sandblast the surface of the aforementioned TA2 titanium alloy plate. The spraying distance was 110 mm, the spraying pressure was 0.2 MPa, and the spraying time was 20 s;

[0053] S2:

[0054] First, the TA2 titanium alloy plate after S1 sandblasting treatment and the prepreg CFRTP (Jiangsu Junhua Special Engineering Plastics Co., Ltd.) were laid in a unidirectional ply structure of [M / 03 / M / 03 / M], where M in [M / 03 / M / 03 / M] represents metal, 03 represents that the laying angle of the prepreg is 0°, the laying layer is 3 layers, and a PEEK film was laminated between each layer of TA2 titanium alloy plate and prepreg CFRTP;

[0055] Subsequently, hot pressing forming is carried out, and the hot pressing process is as follows: starting from room temperature, it is heated to 390 °C at a rate of 10 °C / min and then held for 30 min. Subsequently, it is first cooled to 300 °C and held for 30 min, then further cooled to 170 °C and held for 30 min, and finally cooled to room temperature. The cooling rate during the cooling process is always maintained at 1 °C / min, and the pressure is maintained at 5 MPa throughout the process to obtain a fiber metal laminate.

[0056] The single-lap joint shear test of the TA2 titanium alloy plate and PEEK resin in the fiber metal laminates prepared in the examples and comparative examples of the present invention was carried out according to ASTM D1002 to evaluate the interfacial bonding strength. The test results are as Figure 4 shown. From Figure 4 it can be seen that the interfacial shear strength of the fiber metal laminate obtained in the example of the present invention is as high as 27.8 MPa. It can be seen that compared with the fiber metal laminate of the comparative example, the interfacial shear strength of the fiber metal laminate obtained in the example of the present invention has increased by 180%.

[0057] The mechanical properties of the fiber metal laminates prepared in the examples and comparative examples of the present invention were tested, and the flexural strength and interlaminar shear strength tests were carried out according to ASTM D7264 and ASTM D2344 standards respectively. The test results are as Figure 5 shown. From Figure 5 it can be seen that the flexural strength of the fiber metal laminate obtained in the example of the present invention is as high as 1464.7 MPa, and the interlaminar shear strength is as high as 59.1 MPa. Compared with the fiber metal laminate of the comparative example, the flexural strength and interlaminar shear strength have increased by 178% and 40% respectively.

[0058] As mentioned above, only the preferred specific embodiments of the present invention are described. These specific embodiments are all different implementation manners based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for interfacial modification of a fiber metal laminate, characterized in that, The method includes the following process: First, sandblast the metal surface, then soak it with an ethanol solution of rare earth metal salt for 1 - 3 h. After drying, set a resin film between the metal and the prepreg. The resin film is a PEEK film, and then carry out hot pressing. The concentration of the ethanol solution of rare earth metal salt is 0.1 - 1 wt%, and the rare earth metal salt is selected from chlorides of rare earth elements.

2. The modification method according to claim 1, wherein Sandblasting parameters: the spraying distance is 80 - 180 mm, the spraying pressure is 0.1 - 0.5 MPa, and the spraying time is 15 - 30 s.

3. The modification method according to claim 1, wherein The corundum sand with a mesh size of 40 - 60 is used for sandblasting.

4. A preparation method of a fiber metal laminate with both high interfacial strength and mechanical properties, characterized in that, The method is carried out according to the following steps: Lay the soaked metal and prepreg CFRTP in the unidirectional layering structure of [M / 03 / M / 03 / M] described in any one of claims 1 - 3, and laminate a PEEK film between each layer of metal and prepreg CFRTP. Subsequently, obtain the fiber metal laminate through hot pressing, where in [M / 03 / M / 03 / M], M represents metal, 03 represents that the laying angle of the prepreg is 0°, and the number of laying layers is 3 layers.

5. The method according to claim 4, wherein The hot pressing process is as follows: start from room temperature and heat to 360 - 400 °C at a speed of 5 - 10 °C / min, then hold for 25 - 45 min. Subsequently, cool down to 280 - 320 °C and hold for 25 - 45 min, then continue to cool down to 140 - 180 °C and hold for 25 - 45 min. Finally, cool down to room temperature, and the speed during the cooling process is always maintained at 1 - 10 °C / min. The pressure is maintained at 3 - 6 MPa throughout the process.

6. A fiber metal laminate produced by the method according to claim 4 or 5, characterized in that, Its interfacial shear strength ≥ 27 MPa, bending strength ≥ 1460 MPa, and interlaminar shear strength ≥ 59 MPa.

7. Application of the fiber metal laminate prepared by the method according to claim 4 or 5 in the aerospace field.

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