Interface modification co-grafting method for aluminum / silicon rubber composite material embedded with damping film

Abstract

The invention discloses an interface modification co-grafting method for an aluminum / silicone rubber composite material embedded with a damping film, which combines high-molecular dynamics simulation with a synthesis theory, and simulates a molecular co-grafting reaction process between aluminum / silicone rubber through molecular dynamics. A hydrolysis group alkyl (-C2H5) and a non-hydrolysis group aminopropyl (-NH2) of a silane coupling agent are respectively grafted to hydroxyl on an aluminum metal surface and carbon-carbon double bonds of silicone rubber molecules, an orthogonal experiment method is utilized to design components of the silicone rubber damping material, physical and chemical treatment is carried out on the aluminum surface, and an aluminum / silicone rubber composite material interface co-grafting process is developed. Macro and micro tests show that co-grafting on the modified aluminum surface can effectively improve the bonding performance of an aluminum / silicon rubber interface, the damping performance of the composite material test piece is doubled under the condition that the rigidity of the composite material test piece is not influenced, and a foundation is laid for wide application of metal-based large-damping, anti-seepage, impact-resistant and high-rigidity composite materials.

Description

Technical Field

[0001] The invention relates to the research field of metal-based composite materials with large damping function, in particular to an interface modification co-grafting method of an aluminum / silicone rubber composite material embedded with a damping film. Background Art

[0002] Aluminum / silicone rubber composites with high damping and high specific stiffness are widely used in aerospace, national defense and military fields, such as the shell of avionics equipment, the bulkhead of naval submarines and the outer cover of automobile engines, providing them with additional functions such as anti-leakage, impact resistance, vibration reduction, noise reduction and improved working environment. For the composite of multiple materials with large differences in properties, scholars have conducted in-depth research on the interface bonding process and dynamic theory of embedded co-cured damping composite materials, and have achieved a series of fruitful results, but there are few research reports on the interface modification co-grafting process of aluminum / silicone rubber composites with high damping and high specific stiffness.

[0003] Due to the wide variety of silicone rubbers, their components and processes are different, and the chemical reaction principles of the vulcanization process are also very different, resulting in their performance and uses vary greatly.

[0004] Chinese patent application CN116925552A discloses a silicone rubber composition and a disposable thin film fuse. The silicone rubber composition includes, by weight, 100 parts of vinyl silicone rubber raw rubber, 20-90 parts of POSS modified nano aluminum hydroxide and an appropriate amount of crosslinking agent; the POSS modified nano aluminum hydroxide is prepared by reacting carbon-carbon double bonds and epoxy co-modified nano aluminum hydroxide with amino POSS at a weight ratio of 1:0.05-0.5. The purpose of the invention is to prepare a silicone rubber composition with very good flame retardant and arc erosion resistance, especially for thin film fuses, wherein aluminum hydroxide is a commonly used inorganic filler in silicone rubber that is resistant to leakage tracking and arc erosion, and it has certain flame retardancy, but nano-scale aluminum hydroxide is difficult to disperse in silicone rubber, resulting in the failure to achieve the desired flame retardant and arc erosion resistance. For this reason, the application prepares a silicone rubber composition in which aluminum hydroxide can be easily dispersed in silicone rubber, so that the fuse made of the silicone rubber composition film has better flame retardant and arc erosion resistance. However, the silicone rubber composition cannot be self-grown and co-grafted onto the interface of the aluminum-based composite material, and cannot achieve the dynamic properties possessed by the silicone rubber composite material of the present invention.

[0005] Chinese Patent Application CN105646565B discloses a method for synthesizing nitrile group-containing siloxane and preparing room-temperature condensation-type nitrile silicone rubber. The nitrile group-containing siloxane is prepared by the addition reaction of amino group and double bond between amino group-containing siloxane and nitrile group-containing compound with unsaturated bond, and further the room-temperature condensation-type nitrile silicone rubber is synthesized and prepared by using the nitrile group-containing siloxane. Aiming at the deficiency that domestic and foreign patent documents only report the uses of nitrile silicone rubber raw rubber and do not report the preparation process of nitrile silicone rubber raw rubber, the application makes use of the activation effect of nitrile group on double bond, which is easier to proceed in the reaction than the reaction between ordinary amino group and double bond. The amino group-containing siloxane and the unsaturated compound containing nitrile group are mixed, and through the reaction between the amino group and the double bond in the unsaturated compound, the nitrile group is introduced into the siloxane molecule to obtain the nitrile group-containing siloxane, and the room-temperature condensation-type nitrile silicone rubber can also be further prepared. Similarly, the synthesis of the nitrile group-containing siloxane and the room-temperature condensation-type nitrile silicone rubber cannot self-grow and co-graft onto the interface of the aluminum-based composite material, and it is even more impossible to achieve the kinetic performance of the silicone rubber composite material of the present invention. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide an interface modification co-grafting method for embedding a damping film aluminum / silicone rubber composite material. This method uses aluminum metal as the matrix and silicone rubber film as the functional phase to develop an embedded damping film aluminum / silicone rubber damping composite material. This metal surface treatment technology can effectively improve the bonding performance of the aluminum / silicone rubber interface, and can double the damping performance while hardly affecting the rigidity of the damping composite material specimen, laying a foundation for the wide application of large damping, leak-proof, and impact-resistant metal matrix composite materials.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions: An interface modification co-grafting method for embedding a damping film aluminum / silicone rubber composite material, comprising the following steps: (1). Treat the surface of the aluminum plate. (2). Prepare an embedded damping film aluminum / silicone rubber damping composite material. (3). Hydrolyze the three hydrolyzable groups (-C 2 H 5 ) of the silane coupling agent KH550 molecule to generate silanol and ethanol. (4). The silanol condenses with the hydroxyl group on the surface of the treated aluminum plate to form a chemical bond, realizing the grafting of the silane coupling agent KH550 molecule with the hydroxyl group on the surface of the treated aluminum plate. (5). The non-hydrolyzable group aminopropyl (-NH 2)(1) Carry out polycondensation with the carbon-carbon double bonds in the molecular side chains of the damping film aluminum / silicone rubber damping composite material to construct a molecular bridge, and achieve co-grafting connection at the interface of the damping film aluminum / silicone rubber composite material through molecular chemical bonds.

[0008] The treatment of the aluminum plate surface in step (1) specifically includes: mechanically polishing the aluminum plate to increase the surface roughness value and improve the interface bonding area; cleaning the surface of the aluminum plate with alcohol to remove grease and contaminants; performing anodic oxidation with a 20% sulfuric acid solution to form a dense alumina layer; removing moisture in a drying oven at 100 °C for 2 minutes; finally, performing silanization treatment with a 3% silane coupling agent KH550 solution and leaving it for standby after 120 minutes.

[0009] The damping film aluminum / silicone rubber damping composite material in step (2) is composed of the following components by mass fraction: High tear-resistant silicone rubber raw rubber: 95 - 110 parts Fumed silica: 35 - 42 parts Dihydroxy polydimethylsiloxane: 5 - 9 parts 2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexane: 0.5 - 0.8 parts Silicone oil: 2.5 - 3.2 parts.

[0010] The structure of the embedded damping film aluminum / silicone rubber damping composite material is as follows: Take damping films with different thicknesses after calendering and lay them between two hydroxyl-grafted aluminum plates to form a composite material preform; that is, the upper and lower skins are aluminum plates after surface modification treatment, and the middle is a silicone rubber damping film layer that can be co-grafted to the interface of the modified aluminum sheet.

[0011] The composite preform is placed in a flat vulcanizer mold for the first-stage vulcanization at 170 °C for 8 minutes and the second-stage vulcanization at 200 °C for 2 hours. During the vulcanization process, molecular co-grafting of the damping film and the aluminum plate is achieved. The working pressure per unit area of the flat vulcanization molding mold during the whole process is 1 MPa, and the rate of temperature rise and fall of the mold is 2 °C per minute, thereby obtaining an aluminum / silicone rubber composite workpiece embedded with a damping film, and implementing a new process for interface modification and co-grafting of aluminum / silicone rubber composites. The beneficial effects of the present invention are as follows: The present invention proposes to use aluminum metal as the matrix and silicone rubber film as the functional phase to develop an aluminum / silicone rubber damping composite embedded with a damping film. The components of the damping material are formulated by molecular dynamics simulation and orthogonal experimental method, and an interfacial chemical co-grafting process for aluminum / silicone rubber damping composites is developed to prepare experimental specimens of aluminum / silicone rubber damping composites; through macro- and micro-experiments such as interlaminar shear and free vibration decay, it is shown that this metal surface treatment technology can effectively improve the bonding performance of the aluminum / silicone rubber interface, and while hardly affecting the rigidity of the damping composite specimen, its damping performance is doubled, laying a foundation for the wide application of large damping metal matrix composites. The specific test data are as follows: (1) After surface treatment, the interlaminar shear stress of the aluminum / silicone rubber composite increases from 0.93 MPa of the interlaminar shear stress in the natural bonding state to 9.81 MPa, among which the silanization treatment has the greatest influence, increasing the shear stress by 3.24 MPa.

[0012] (2) By changing the thickness of the damping layer and measuring the vibration reduction and noise reduction performance of the aluminum / silicone rubber composite, it is found that when the thickness of the silicone rubber damping layer increases from 0 mm (2-mm thick aluminum plate) to 0.1 mm, the damping ratio is increased to 3.4 times that of the undamped aluminum plate, and at the same time, the frequency change is only 0.90 Hz, indicating that the aluminum / silicone rubber composite significantly improves the damping performance while having a negligible impact on the stiffness of the metal material. Description of the Drawings

[0013] Figure 1 Structure diagram of the aluminum / silicone rubber composite embedded with a damping film, where: the upper and lower skins are aluminum plates after surface modification treatment, and the middle is a silicone rubber damping film layer that can be co-grafted to the interface of the modified aluminum sheet; Figure 2 It is the schematic diagram of the silanization co-grafting reaction between the aluminum / silicone rubber interface; Figure 3 It is a molecular monomer model, where (a) is an aluminum unit cell, (b) is a silicone rubber molecular model, and (c) is a KH550 monomer model; Figure 4 It is a natural adsorption model diagram of aluminum / silicone rubber; Figure 5 It is an interface co-grafting model diagram of aluminum / silicone rubber; Figure 6 is the process flow chart of aluminum metal surface treatment; Figure 7 is the vulcanization curve graph of silicone rubber specimens #1 - #5; Figure 8 is the compression set graph of silicone rubber; Figure 9 is the aluminum / silicone rubber composite specimen, where: (a) is the structural diagram of the experimental specimen, (b) is the experimental specimen after being broken; Figure 10 is the interlaminar shear strength graph of aluminum / silicone rubber composites under different treatment processes; Figure 11 is the surface micro - morphology graph, where: (a) is before anodizing of the aluminum plate, (b) is after anodizing of the aluminum plate; Figure 12 is the free - vibration material damping test system, where: (a) is the experimental platform, (b) is the experimental specimen; Figure 13 is the free - vibration displacement attenuation curve graph of different damping layer thicknesses, where: (a) is the comparison of free - vibration displacement attenuation curves of specimens 1 and 2, (b) is the comparison of free - vibration displacement attenuation curves of specimens 3 and 4; Figure 14 is the amplitude - frequency curve graph of aluminum / silicone rubber composites with different damping layer thicknesses, where: (a) is the amplitude - frequency curve of specimen 1, (b) is the amplitude - frequency curve of specimen 2, (c) is the amplitude - frequency curve of specimen 3, (d) is the amplitude - frequency curve of specimen 4; Figure 15 is the damping ratio graph of aluminum / silicone rubber composites with different damping layer thicknesses; Figure 16 is the morphology analysis graph after shear failure of aluminum / silicone rubber composites; Figure 17 is the interlaminar interface graph of aluminum / silicone rubber composites before and after surface treatment; Figure 18 is the interlaminar fine spectrum of aluminum / silicone rubber composites before and after surface treatment: C1s peak, where: (a) is the interlaminar fine spectrum before surface treatment, (b) is the interlaminar fine spectrum after surface treatment. Specific implementation manners

[0014] The following further describes the present invention in conjunction with the appended Figure 1 to the appended Figure 18 drawings and embodiments.

[0015] The structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the ratio relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear narration and are not used to limit the scope within which the present invention can be implemented. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope within which the present invention can be implemented. Example 1:

[0016] 1. Materials used in the example Self-made silicone rubber, including the following components by mass fraction: High tear-resistant silicone rubber raw gum (HXR-8355U) 95 - 110 parts; 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DBPH, Aksu 101) 0.5 - 0.8 parts; Fumed silica (R972) 35 - 42 parts; Dihydroxypolydimethylsiloxane (1112 - 39 - 6) 5 - 9 parts; Silicone oil (HMX200) 2.5 - 3.2 parts; There are also commercially available silane coupling agent (KH550) and multiple pieces of aluminum sheets (160mm×25mm×1mm).

[0017] 2. Molecular dynamics simulation In order to improve Figure 1 the interfacial bonding performance and the overall structural dynamic performance of the embedded damping film aluminum / silicone rubber composite structure shown, where the upper and lower skins are aluminum plates after surface modification treatment, and the middle is a silicone rubber damping film layer that can be co-grafted to the interface of the modified aluminum sheet. This application proposes to graft the hydrolyzable group alkyl (-C 2 H 5 ) and the non-hydrolyzable group aminopropyl (-NH 2 ) of the silane coupling agent KH550 to the hydroxyl group on the surface of the treated aluminum metal and the carbon-carbon double bond of the silicone rubber molecule respectively. The specific interfacial co-grafting principle is as shown in Figure 2 ; In order to verify the effectiveness of the co-grafting theory shown in Figure 2 , using the Visualizer module in the Material Studio software, construct the molecular monomer models of the aluminum unit cell, silicone rubber, and KH550 during the interfacial co-grafting process of the aluminum / silicone rubber composite, specifically as shown in Figure 3As shown Figure 3 Among them: purple represents Al atoms, white represents H atoms, gray represents C atoms, red represents O atoms, and blue represents N atoms.

[0018] The microscopic molecular binding energy of the interface of the aluminum / silicone rubber composite material before and after the surface treatment of aluminum was simulated using Material Studio software. An amorphous cell of silicone rubber was constructed and imported into the aluminum cell model. Specifically, as Figure 4 shown, by calculating the energies of different models, the formula for the adsorption energy of aluminum and silicone rubber in the natural state can be obtained as follows: (1) In formula (1): E Al-Rubber is the energy of the aluminum / silicone rubber composite cell; E Al is the energy of the aluminum cell; E Rubber is the energy of the amorphous cell of silicone rubber; E Adsorption is the adsorption energy between the interfaces of two molecules of aluminum / silicone rubber. The calculated free energy results are listed in Table 1, and the adsorption energy of aluminum metal and silicone rubber in the natural state is 197.665 kcal / mol.

[0019] Table 1 Calculation results of free energy

[0020] After surface treatment, the co-grafting process of the interface of the aluminum / silicone rubber composite material is as Figure 5 shown. An alumina film is formed on the aluminum surface by anodic oxidation, hydroxyl groups are adsorbed, and MeOH-Si bonds are formed with the hydrolyzed groups of KH550, realizing the surface grafting of modified aluminum and KH550; the aminopropyl group of KH550 undergoes polycondensation with the olefin double bond of silicone rubber to form strong chemical bonds, and the binding energy is as high as 648.207 kcal / mol, far exceeding the natural adsorption energy, and can realize the co-grafting of the interface between KH550 and silicone rubber, theoretically demonstrating the feasibility of the co-grafting theory proposed in the present invention.

[0021] 3. Surface modification of aluminum In order to realize Figure 2 the co-grafting principle shown Figure 5 and the co-grafting process of the interface between aluminum and silicone rubber simulated Figure 6 as shown, the surface of aluminum metal needs to be surface-treated as

[0022] shown first. The process steps include: mechanical polishing to enhance the surface roughness value and increase the bonding area of the bonding surface; cleaning with alcohol to remove grease and contaminants; anodic oxidation using a 20% sulfuric acid solution to form a dense alumina layer; removing moisture in a drying oven at 100 °C for 2 minutes; finally, silanization treatment with a 3% KH550 solution and leaving it for standby after 120 minutes. Due to the presence of a large number of Si-O bonds and linear or branched chain structures in silicone rubber, it has excellent chemical stability and high-temperature resistance; the double-25 vulcanizing agent promotes the cross-linking of silicone rubber to form a three-dimensional network, enhancing its mechanical properties such as tensile strength and elasticity; silica, as a filler, not only enhances the material stability but also prevents shrinkage through its interaction with silicon-oxygen bonds, improving elasticity and lifespan; to optimize the mechanical properties of silicone rubber, KH550 silicone rubber was effectively co-grafted onto the aluminum substrate. In this application research, with the double-25 vulcanizing agent and fumed silica as variables, an orthogonal experimental table 2 was designed to determine the optimal damping material components.

[0023] Table 2 Orthogonal experimental components

[0024] 5. Instruments used for performance test characterization A rotorless vulcanizer (M-3000AU) was used to evaluate the vulcanization performance of silicone rubber; a tensile testing machine AL-7000S and a hardness tester were used to test the tensile strength and hardness of the vulcanized specimens; a compression set device was used to measure the compression set of silicone rubber; a universal tensile testing machine was used to test the interlaminar shear performance of the aluminum / silicone rubber composite specimens; the Lab Shop software and a damping test system were used to conduct a free vibration decay experiment on the aluminum / silicone rubber composite; a scanning electron microscope SEM was used to analyze the microscopic morphology of the bonding surface of the composite specimens after shear failure; an X-ray photoelectron spectrometer was used to analyze the elemental composition and chemical state at the interface of the aluminum / silicone rubber composite.

[0025] 6. Vulcanization performance of silicone rubber Using a rotorless vulcanizer, five groups of silicone rubber were vulcanized and tested at 170 °C, and the results are as Figure 7 shown in Table 3. Figure 7 The relationship between the torque and vulcanization time during the process shows the vulcanization speed. A gentle curve change indicates the completion of vulcanization, and a high torque indicates a high degree of cross-linking and thorough vulcanization. The analysis shows that the 4# component has the fastest vulcanization speed, with a cross-linking degree as high as 51.214, showing excellent vulcanization characteristics. The results have important reference value for component selection.

[0026] Table 3 Vulcanization parameters

[0027] 7. Mechanical property test of silicone rubber damping material The tensile strength and hardness of the vulcanized samples were tested using a tensile testing machine and a hardness tester. Table 4 shows the mechanical properties of different silicone rubber components. Observing the data of samples 2#, 4#, and 5#, it was found that the increase in carbon black content weakened the mechanical properties of the rubber; this is because too much carbon black will hinder the movement of the molecular chain, causing the material to become brittle and hard, reducing the elasticity and impact resistance of the material; at the same time, the agglomeration phenomenon caused by high carbon black content will form stress concentration points, further weakening the mechanical properties of the material; and the data of 1#, 2#, and 3# show that an appropriate amount of vulcanizer can improve the performance of rubber, but excessive use will cause excessive cross-linking, shorten the distance between molecular chains, reduce the elongation at break, and may trigger new chemical reactions, affecting the stability and processability of the material.

[0028] 8. Silicone rubber compression set The compression permanent deformation of silicone rubber was measured using a compression permanent deformation device. The silicone rubber of different components was subjected to a compression test at 100°C for 24 hours, and then the compression permanent deformation was tested after being placed at room temperature for 30 minutes. The results are as follows Figure 8 As shown. Component 4# recovered quickly after high temperature compression, and the residual deformation was only 2.99%. This was mainly due to the adsorption of unsaturated double bonds between carbon black and silicone rubber molecular chains, which promoted the cross-linking reaction, strengthened the connection between molecular chains, reduced the absorption of interface heat, and thus reduced the compression permanent deformation. Based on the above tests, component 4# showed excellent mechanical properties and was therefore selected as the damping functional material in aluminum / silicone rubber composites.

[0029] Table 4 Mechanical properties of silicone rubber

[0030] 9. Preparation process of composite materials Take 4# component silicone rubber damping material, thin the mixed rubber to 1mm thick, and follow Figure 9 As shown, it is laid between two processed aluminum sheets with specifications of 160mm×25mm×1mm to form a composite material preform, and then the composite material preform is placed in a flat-plate vulcanizer mold for a first-stage vulcanization at 170℃ for 8min and a second-stage vulcanization at 200℃ for 2h. During the vulcanization process, the molecules of silicone rubber and aluminum metal are co-grafted. During the whole process, the working pressure per unit area of ​​the flat-plate vulcanization molding mold is 1MPa, and the rate of temperature rise and fall of the mold is 2℃ / minute, so as to obtain an aluminum / silicone rubber composite workpiece embedded with a damping film, realizing the implementation of a new process of co-grafting of interface modification of aluminum / silicone rubber composite materials.

[0031] 10. Effect of metal surface treatment process on interlaminar shear properties of aluminum / silicone rubber composites The interlaminar shear properties of aluminum / silicone rubber composite specimens were tested using a universal tensile testing machine. Figure 10shows the maximum shear stress between layers of aluminum / silicone rubber composites after different surface treatments; the data shows that the maximum shear stress between layers increased by 3.24 MPa after silanization treatment. This enhancement effect stems from the hydrolysis, condensation, and polycondensation reactions occurring at the aluminum / silicone rubber interface, and the introduction of active aminopropyl groups that can crosslink with the olefin double bonds of silicone rubber, thereby forming a co-grafted molecular bridge on the aluminum surface, specifically as shown in Figure 2 and Figure 5 shown. Here, the silanization reaction mechanism involves the following steps: First, the three hydrolyzable groups of KH550 molecules undergo hydrolysis reactions to generate silanol groups and ethanol; then, the silanol groups condense with the hydroxyl groups on the surface of the treated aluminum metal to form chemical bonds, achieving the grafting of KH550 to the metal. At the same time, the organic groups on the other side of the KH550 molecule undergo polycondensation with the carbon-carbon double bonds in the side chains of silicone rubber molecules to construct a molecular network, and then the co-grafted bonding of the aluminum / silicone rubber composite is realized through molecular chemical bonds. The secondary vulcanization improves the shear strength of the aluminum / silicone rubber composite from the root by eliminating bubble defects on the rubber surface and enhancing various properties such as the strength and toughness of the rubber. Mechanical polishing removes contaminants on the metal surface, optimizes the bonding conditions, increases the bonding area, promotes the deep penetration and firm bonding of the bonding material, and further enhances the shear strength. Anodic oxidation forms a thick and dense alumina film on the metal surface, as shown in Figure 11 shown. Natural oxidation only produces a thin oxide film of about 5 - 20 nm, and the characteristics of this surface are difficult to observe under an electron microscope. While the thickness of the oxide film after anodic oxidation can reach 60 μm, and the surface is porous, which is conducive to adsorbing hydroxyl groups in the air and providing more crosslinking sites for interfacial reactions.

[0032] 11. Influence of damping layer thickness on the damping performance of aluminum / silicone rubber composites To explore the influence of damping layer thickness on the damping performance of aluminum / silicone rubber composites, a free vibration decay experiment was conducted on the aluminum / silicone rubber composites using Lab Shop software and a damping test system, specifically as shown in Figure 12 shown. The thicknesses of the silicone rubber films are 0 mm, 0.1 mm, 0.2 mm, and 0.3 mm respectively. Figure 13 and Figure 14 show the corresponding decay curves and amplitude-frequency diagrams. By fitting the peak data using the vibration equation of a single-degree-of-freedom system, the relationship between the damping ratio and the damping layer thickness is obtained as shown in Figure 15 ; the results show that the damping layer thickness and the damping ratio do not change linearly. This is mainly because the rubber damping mechanism tends to saturate as the thickness increases, and the growth rate of the damping ratio decreases; when the thickness of the silicone rubber damping layer increases from 0 mm (2 mm thick aluminum plate) to 0.1 mm, the damping ratio increases to 3.4 times that of the pure aluminum plate, and at the same time, the frequency changes by only 0.90 Hz, indicating that the aluminum / silicone rubber composite significantly improves the damping performance while having a negligible impact on the stiffness of the metal material.

[0033] 12. Microscopic failure morphology analysis The cross-section of the aluminum / silicone rubber composite specimen with interfacial failure was scanned at 500 times magnification using SEM, as specifically shown in Figure 16 the following. The results showed that after shear failure, the silicone rubber was tightly bonded to the surface of the treated aluminum metal, and no obvious separation interface was observed. There were fine protrusions or depressions on the bonding surface, which were due to the anchoring effect between the texture formed on the metal surface by mechanical grinding and the rubber, and the result of the tight fitting of the rubber and the metal surface by hot pressing. The silanization treatment acted as a molecular bridge between the interfaces, and promoted the grafting reaction through the co-grafting cross-linking of molecular groups. The failure occurred inside the silicone rubber matrix, belonging to the failure of the rubber matrix, which indicated that the interfacial bonding performance of the aluminum / silicone rubber composite was very good.

[0034] 13. X-ray photoelectron spectroscopy analysis The interfacial layer of the aluminum / silicone rubber composite before and after surface treatment was scanned using an X-ray photoelectron spectrometer. Figure 17 and Figure 18 show the scanning spectra, the main components of which are C, O, and Si. By performing a detailed spectral analysis of its C1s peak, the change in its chemical state was studied. The binding energies of C-C, C=C, C-O, and C-Si are 284.8 eV, 284.00 eV, 287.46 eV, and 283.13 eV, respectively. Figure 17 and Figure 18 It shows that after surface treatment, the area ratio of C-C increased from 66.17% to 77.66%, and that of C-Si increased from 13.97% to 20.08%. At the same time, the C=C peak disappeared, indicating that the introduction of the active group aminopropyl at the interface was accompanied by the addition of C-Si, and the polycondensation reaction of aminopropyl and silicone rubber led to the breakage of the unsaturated double bonds in the rubber molecular chain. This confirmed the formation of chemical bonding and co-grafted molecular bridges between the interfaces, enhancing the interfacial bonding performance.

[0035] The present invention combines polymer kinetic simulation and its synthesis theory, and proposes to graft the alkyl group (-C 2 H 5 ) and aminopropyl group (-NH 2 ) of the silane coupling agent KH550 onto the hydroxyl group on the surface of the treated aluminum metal and the carbon-carbon double bond of the silicone rubber respectively. The effectiveness of the co-grafting reaction of the interfacial molecules of the aluminum / silicone rubber composite was verified through simulation; the components of the silicone rubber damping material were optimized using orthogonal experiments, and combined with the macro and micro tests and chemical state analysis of the interfacial layer of the aluminum / silicone rubber composite, the correctness of the theory proposed in this application was verified, achieving a huge improvement in the interfacial bonding performance at the chemical bond level. The conclusions are as follows: After surface treatment, the interlaminar shear stress of the aluminum / silicone rubber composite material increases from 0.93 MPa in the natural bonding state to 9.81 MPa. Among them, the silanization treatment has the greatest influence, increasing the shear stress by 3.24 MPa.

[0036] (2) By changing the thickness of the damping layer and measuring the vibration damping and noise reduction performance of the aluminum / silicone rubber composite material, it is found that when the thickness of the silicone rubber damping layer increases from 0 mm (2-mm thick aluminum plate) to 0.1 mm, the damping ratio increases to 3.4 times that of the pure aluminum plate, and the frequency change is only 0.90 Hz. This indicates that while significantly improving the damping performance, the influence of the aluminum / silicone rubber composite material on the stiffness of the metal material is negligible.

[0037] Although the specific embodiments of the present invention have been described in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made without creative efforts by those skilled in the art are still within the protection scope of the present invention.

Claims

1. A co-grafting method for interface modification of aluminum / silicone rubber composite material embedded with damping film, characterized in that: The following steps are involved: (1). Treat the surface of the aluminum plate; (2). Preparation of aluminum / silicone rubber damping composite material embedded with damping film; (3) The three hydrolyzable groups (-C2H5) of the silane coupling agent molecule undergo hydrolysis reaction to generate silanol groups and ethanol; (4). The silanol groups condense with the hydroxyl groups on the surface of the treated aluminum plate to form chemical bonds, thereby achieving the grafting of the silane coupling agent molecules with the hydroxyl groups on the surface of the treated aluminum plate; (5) The non-hydrolyzable aminopropyl (-NH2) group of the silane coupling agent molecule undergoes condensation polymerization with the carbon-carbon double bonds of the side chains of the damping film aluminum / silicone rubber damping composite material molecules to construct a molecular bridge, thereby achieving co-grafting connection at the interface of the damping film aluminum / silicone rubber composite material through molecular chemical bonds.

2. The method for interfacial modification and co-grafting of aluminum / silicone rubber composite materials embedded with damping film as claimed in claim 1, characterized in that: The surface of the aluminum plate in step (1) is treated, specifically including: mechanically grinding the aluminum plate to increase the surface roughness value and improve the interface bonding area; using alcohol to clean and remove grease and pollutants on the surface of the aluminum plate; using 20% ​​sulfuric acid solution to perform anodizing to form a dense aluminum oxide layer; removing moisture in a 100° C. drying oven for 2 minutes; and finally, performing silanization treatment with 3% silane coupling agent KH550 solution for 120 minutes for use.

3. The method for interfacial modification and co-grafting of aluminum / silicone rubber composite materials embedded with damping film as claimed in claim 1, characterized in that: The damping film aluminum / silicone rubber damping composite material in step (2) is composed of the following components according to mass fraction: High tear resistance silicone rubber 95-110 parts Fumed silica 35-42 parts 5-9 parts of dihydroxy polydimethylsiloxane 2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexane 0.5-0.8 parts 2.5-3.2 parts of silicone oil.

4. The method for interfacial modification and co-grafting of aluminum / silicone rubber composite materials embedded with damping film as claimed in claim 1, characterized in that: Damping films of different thicknesses after thin-pass are laid between two hydroxyl-grafted aluminum plates to form a composite material preform; that is, the upper and lower skins are surface-modified aluminum plates, and the middle is a silicone rubber damping film layer that can be co-grafted to the interface of the modified aluminum sheet.

5. The method for interfacial modification and co-grafting of aluminum / silicone rubber composite material embedded with damping film as claimed in claim 4, characterized in that: The composite preform was placed in a flat-plate vulcanizer mold for a first-stage vulcanization at 170°C for 8 min and a second-stage vulcanization at 200°C for 2 h. During the vulcanization process, the molecules of the damping film aluminum / silicone rubber damping composite material and the aluminum plate were co-grafted. During the whole process, the working pressure per unit area of ​​the flat-plate vulcanization molding mold was 1 MPa, and the rate of mold temperature rise and fall was 2°C / minute, thereby obtaining an aluminum / silicone rubber composite workpiece embedded with a damping film, realizing the implementation of a new process of co-grafting of the interface modification of the aluminum / silicone rubber composite material.

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