A continuous carbon fiber-based fe / al laminated composite material and a method for manufacturing the same

Abstract

The application relates to the technical field of metal-metal intermetallic compound layered composite materials, and discloses a Fe / Al layered composite material based on continuous carbon fibers and a preparation method thereof, which comprises the following steps: alcohol immersion is performed on continuous carbon fiber tows, and then pretreatment is performed to obtain pretreated continuous carbon fiber tows; the pretreated continuous carbon fiber tows are subjected to double-plating layer gradient modification; a stainless steel foil is polished, and then etching is performed to obtain a standby stainless steel foil, which is then stacked with the modified continuous carbon fiber tows, fixed sintering is performed in a graphite mold, and a Fe / Al layered composite material based on continuous carbon fibers is obtained. The layered composite material obtained by the application has excellent interface combination, and no interface cracking and obvious defects are generated between the continuous fibers and the transition layer. Compared with a traditional Fe / Al layered composite material, the overall mechanical performance of the composite material prepared by the preparation process is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal-metal intermetallic compound layered composite material, in particular to a Fe / Al layered composite material based on continuous carbon fiber and a preparation method thereof. BACKGROUND

[0002] Metal-metal intermetallic compound layered composite material is a new type of material imitating the laminated structure of natural shell. The shell has a special "brick and mud" structure (i.e. brittle layer and ductile layer are overlapped with each other), which greatly improves the strength and toughness of the material. First, the layered composite material utilizes the deformation and bridging of the metal layer to passivate the crack, and the deflection of the metal-metal intermetallic compound interface to the crack will hinder the crack propagation, which makes the layered composite material extremely advantageous in strength, plasticity and impact resistance. Second, the comprehensive mechanical properties of the layered composite material can be determined by selecting the composition and thickness of the foil, and the type and volume fraction of the final generated phase can also be controlled by adjusting the stacking mode and preparation process of the foil, and these characteristics make the composite material very suitable for realizing the engineering microstructure with specific performance. On the other hand, in order to better improve the plastic deformation capacity of the composite material, introducing a reinforcing body into the intermetallic compound is a new way for the development of layered composite materials. The reinforcing body has various types, mainly including continuous long fibers and short fibers. In addition, the layered composite material is also very suitable for the production of commercial, military and dual-purpose expandable structural materials (such as civilian armor, tank armor, etc.) and the application fields of aerospace and aviation which require lightweight and high specific performance.

[0003] So far, among the whole MIL composite material family, Ti / Al MIL composite material has been widely and deeply studied. For Ti / Al system, because is the only phase formed by reaction sintering, and the intermetallic compound belongs to a hard and brittle phase, which greatly limits the flexible adjustment of material performance. In order to seek a composite material with excellent comprehensive mechanical properties and save cost, Fe / Al composite material has gradually been deeply studied by people. There are five kinds of intermetallic compounds in Fe / Al system, and these five kinds of intermetallic compounds can undergo phase transition at a relatively low temperature range, which makes the material itself have extremely high designability. Second, the preparation cost of Fe foil is much lower than that of Ti foil in Ti-Al system, which makes the research of Fe / Al composite material have a very broad application prospect.

[0004] In the preparation technology of MIL composite materials: people have developed rolling composite method, explosive composite method, discharge sintering method, vacuum hot pressing sintering method and other technical methods. In order to better meet the requirements of people on the quality and efficiency of material preparation, the fast hot pressing sintering method (FHP) as a new type of material preparation method is introduced into the preparation process of MIL composite materials. On the one hand, the raw materials are placed in the high vacuum heating zone according to the designed composite method, and the high pressure hydraulic pressure head is used to provide stable pressure output, so as to ensure the uniformity of the microstructure of the materials. On the other hand, through rapid heating, the elements in the composite materials always maintain a high mutual diffusion speed, and finally a good metallurgical bonding effect is obtained.

[0005] Therefore, it has important practical significance to provide a continuous carbon fiber based Fe / Al layered composite material prepared by the fast hot pressing sintering method and a preparation method thereof. SUMMARY

[0006] Therefore, the present application provides a continuous carbon fiber based Fe / Al layered composite material and a preparation method thereof, which aims to solve at least one of the problems in the above background art.

[0007] The present application provides a preparation method of a continuous carbon fiber based Fe / Al layered composite material, comprising the following steps:

[0008] The continuous carbon fiber tows are alcohol immersed, and then pretreated to obtain pretreated continuous carbon fiber tows;

[0009] The pretreated continuous carbon fiber tows are subjected to double plating layer gradient modification to obtain modified continuous carbon fiber tows;

[0010] The stainless steel foil is polished, and then etched to obtain a standby stainless steel foil;

[0011] The standby stainless steel foil and the modified continuous carbon fiber tows are stacked and fixed and sintered in a graphite mold to obtain the continuous carbon fiber based Fe / Al layered composite material.

[0012] Preferably, the parameters of alcohol immersion are that the continuous carbon fiber tows are placed in ethanol and left for 30-35 minutes; the pretreatment is specifically that the alcohol immersed continuous carbon fiber tows are transferred to new anhydrous ethanol for rinsing to remove the dissolved oil stains and impurities, and finally drained; the stainless steel foil comprises 0.04mm 1060 aluminum foil, 0.04mm 430SS foil and 0.2mm 304SS foil.

[0013] Preferably, the dual-coating gradient modification specifically involves: depositing a 50-100 nm Ni-P alloy transition layer on the surface of the pretreated continuous carbon fiber bundle using magnetron sputtering, followed by coating a 20-50 nm layer using a sol-gel method. Nanocoating.

[0014] Preferably, the parameters of the magnetron sputtering technology are: vacuum degree is - The working pressure is 0.3Pa-0.5Pa; the sputtering power is 280W-320W; and the atmosphere is Ar.

[0015] The sol-gel method specifically involves: adding aluminum nitrate and citric acid sequentially to ethanol, stirring at 300-400 rpm for 3-4 hours under a constant temperature water bath at 50-60℃ to form a transparent and uniform sol, and then allowing it to stand at room temperature for 24-36 hours for aging; coating using an impregnation-coating method, immersing the pretreated continuous carbon fiber bundle into the sol for 30-40 seconds, then uniformly removing it at a lifting speed of 2-3 mm / s, and air-drying it at room temperature for 10-15 minutes; then placing it in a vacuum drying oven and drying it at 80-100℃ for 2-3 hours; wherein the molar ratio of aluminum nitrate:citric acid:ethanol is 1:1.2:8~1:1.5:10.

[0016] Preferably, the polishing of the stainless steel foil specifically involves polishing the stainless steel foil using a low-temperature plasma bombardment method. The parameters of the low-temperature plasma bombardment method are: power 300~350W, time 2~4min; and the atmosphere of the low-temperature plasma bombardment method is Ar gas.

[0017] Preferably, the etching specifically involves using an ultrasonic-assisted electrochemical etching process to etch the surface of a stainless steel foil to form a nanoscale uneven structure.

[0018] Preferably, the ultrasonic-assisted electrochemical etching process specifically involves: using a stainless steel foil as the anode and a platinum sheet as the cathode, with the electrode spacing controlled at 30mm-40mm; and selecting an electrolyte of 0.5mol / L-0.8mol / L. The solution and electrolyte temperature are 25℃-30℃; ultrasonic assistance is introduced during the etching process, with an ultrasonic power of 250W-300W and an ultrasonic frequency of 40kHz-50kHz; the applied DC current density is... After etching is completed, the stainless steel foil is quickly removed and rinsed with deionized water 3-5 times to remove residual electrolyte on the surface. Then it is ultrasonically cleaned in anhydrous ethanol for 10-15 minutes and finally dried in a vacuum drying oven at 60℃-80℃ for 1-2 hours.

[0019] Preferably, the stack is stacked with 304SS foil-multilayer foil micro-unit-304SS foil as a stack unit, and a single sample contains five stack units, wherein the specific stacking mode of the multilayer foil micro-unit is: Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al.

[0020] Preferably, the sintering includes a first sintering stage and a second sintering stage, the first sintering stage is: rapidly heated at a heating rate of 100℃ / min, heated to 550℃, and then heated to 600-650℃ at a heating rate of 50℃ / min and kept; the second sintering stage is: heated to 850-950℃ at a heating rate of 100℃ / min and kept.

[0021] The application also provides a continuous carbon fiber-based Fe / Al laminated composite material, which is obtained by the preparation method described in the above technical solution.

[0022] Compared with the prior art, the application has the following beneficial effects:

[0023] (1) The Fe / Al composite material prepared by the "multilayer foil and two-stage method" process has faster reaction speed, shorter preparation period and higher yield compared with the traditional sintering process. In addition, compared with the Ti / Al laminated composite material, it also has obvious advantages such as low cost and high specific performance.

[0024] (2) The Fe / Al laminated composite material prepared by the application can be found through microstructure observation: the interfaces are excellent, and there is no interface cracking and obvious defects between the continuous fibers and the transition layer. In the direction perpendicular to the stack, the compressive strength reaches 3019MPa, and the bending strength reaches 855MPa; in the direction parallel to the stack, the compressive strength reaches 2090MPa, and the bending strength reaches 687MPa. Compared with the traditional Fe / Al laminated composite material, the overall mechanical properties of the composite material prepared by the preparation process are much higher than those of the former and have been significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of preferred embodiments and are not meant to limit the present application. Furthermore, the same reference numerals are used throughout the several drawings to represent similar components. In the drawings:

[0026] Figure 1 Schematic diagram of original foil and continuous carbon fiber stacking mode;

[0027] Figure 2 SEM image of the micro-morphology of the reaction interface of the composite material of the present application;

[0028] Figure 3 X-ray diffraction pattern of the continuous carbon fiber reinforced Fe / Al laminated composite material prepared by the present application;

[0029] Figure 4 Bending stress-strain curve of the laminated composite material of the present application along the vertical / parallel direction to the stacking direction;

[0030] Figure 5 Quasi-static compression stress-strain curve of the laminated composite material of the present application along the vertical / parallel direction to the stacking direction. DETAILED DESCRIPTION

[0031] A number of exemplary embodiments of the present application are described in detail below, which should not be considered limiting on the present application, but rather as being illustrative. It should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application.

[0032] In addition, for numerical ranges that are expressly recited herein, it is to be understood that every intervening value between the upper and lower limits of the range is also specifically disclosed. In addition, each smaller range that falls within the integer ranges are also specifically disclosed. The upper and lower limits of these smaller ranges can independently be included or excluded in the range.

[0033] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe in further detail the methods and / or materials associated with the documents. In the case of conflict between the present specification and any document incorporated by reference, the present specification will control.

[0034] Many modifications and variations of this application can be made in the light of the above teachings without departing from the spirit and scope thereof, and it is to be understood that all such modifications and variations warrant the patentable subject matter under the patent laws. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only. It is to be understood that the application is not limited in its application to the details set forth in the above description.

[0035] As used herein, "comprise", "comprising", "having", "including", "contain", "containing", "include" and "including" are open-ended terms that are intended to mean one or more of the stated elements or steps are present, but do not exclude the presence of one or more other elements or steps.

[0036] The present application provides a preparation method of a continuous carbon fiber-based Fe / Al layered composite material, comprising the following steps:

[0037] The continuous carbon fiber tows are subjected to alcohol immersion, and then pretreated to obtain pretreated continuous carbon fiber tows;

[0038] The pretreated continuous carbon fiber tows are subjected to double-plating layer gradient modification to obtain modified continuous carbon fiber tows;

[0039] The stainless steel foil is polished, and then etched to obtain a standby stainless steel foil;

[0040] The stainless steel foil and the modified continuous carbon fiber tows are stacked, and then fixed and sintered in a graphite mold to obtain the continuous carbon fiber-based Fe / Al layered composite material.

[0041] The continuous carbon fiber tows are subjected to alcohol immersion, and then pretreated to obtain pretreated continuous carbon fiber tows;

[0042] The present application first subjects the continuous carbon fiber tows to alcohol immersion, efficiently removes components such as oil stains and organic impurities on the surface of the tows, and the alcohol as a polar solvent can quickly strip such impurities by dissolution; in combination with the subsequent step of "transferring to new anhydrous ethanol for rinsing", the dissolved impurities can be further removed to avoid their secondary adsorption on the surface of the tows, thereby providing a uniform and impurity-free attachment base for the subsequent "double-plating layer gradient modification", avoiding defects such as pinholes and peeling of the plating layer caused by impurities, and ensuring the interface bonding quality.

[0043] In the present application, the parameters of the alcohol immersion are preferably that the continuous carbon fiber tows are placed in ethanol and left for 30-35 minutes; the pretreatment is specifically preferably that the continuous carbon fiber tows subjected to alcohol immersion are transferred to new anhydrous ethanol for rinsing to remove the dissolved oil stain impurities, and finally drained; the stainless steel foil preferably comprises a 0.04 mm 1060 aluminum foil, a 0.04 mm 430SS foil, and a 0.2 mm 304SS foil.

[0044] The pretreated continuous carbon fiber tows are subjected to double-plating layer gradient modification to obtain modified continuous carbon fiber tows;

[0045] In the present application, the double-plating layer gradient modification is specifically preferably that a 50-100 nm Ni-P alloy transition layer is deposited on the surface of the pretreated continuous carbon fiber tows by using a magnetron sputtering technology, and then a 20-50 nm Nano-coating.

[0046] Continuous carbon fibers need to be simultaneously combined with two substrates of stainless steel (Fe-based) and aluminum foil (Al-based), and the wettability of carbon fibers with Fe and Al is quite different. The gradient modification of double plating layers realizes precise matching through "layered adaptation": in the inner layer of the Ni-P alloy transition layer (50-100 nm), the Ni element has high compatibility with the Fe element of the stainless steel substrate (430SS foil, 304SS foil), which can form a stable metal bond through diffusion welding, avoiding the interface peeling problem caused by poor wettability when carbon fibers directly contact with the Fe substrate; the outer layer of the nano-coating (20-50 nm) can form good physical adsorption and chemical combination with the Al substrate, and at the same time the chemical stability can avoid the direct reaction of Al with carbon fibers, solving the technical pain point that a single plating layer cannot simultaneously adapt to the Fe and Al double substrates, and significantly improving the interface bonding strength of carbon fibers with the two metal substrates.

[0047] In addition, the gradient modification of double plating layers can also inhibit the generation of brittle phases and ensure the toughness of the composite material. During the subsequent sintering process, if the carbon fibers directly contact with the Al substrate, chemical reaction is easy to occur to generate brittle phases (which are easy to accumulate at the interface, leading to a decrease in the fracture toughness of the composite material). The nano-coating in the double plating layers can act as a physical barrier to block the direct diffusion channel of carbon fibers and Al atoms, thereby inhibiting the generation of brittle phases from the root; at the same time, the inner layer of the Ni-P alloy transition layer has a certain plasticity, which can buffer the interface stress through micro-deformation when stressed, avoiding interface cracking caused by stress concentration, and taking into account the strength and toughness of the composite material.

[0048] During the transfer and stacking process of continuous carbon fibers from pretreatment to sintering, the surface is easy to be slightly oxidized due to contact with air, or to adsorb small impurities in the environment, affecting the subsequent bonding effect with the metal substrate. The nano-coating in the double plating layers can effectively prevent the surface oxidation of carbon fibers and the adsorption of impurities, and improve the bonding effect with the metal substrate. ​​The nano coating has compactness (porosity is less than or equal to 3%), can form a stable protective layer on the surface of the carbon fiber, isolate air and impurities, avoid secondary pollution or oxidation of the surface of the carbon fiber; at the same time, the Ni-P alloy transition layer can enhance the high-temperature oxidation resistance of the carbon fiber, provide protection for subsequent high-temperature sintering at 850 DEG C-950 DEG C, prevent the carbon fiber from structural degradation at high temperature, and ensure the process stability. The double plating layer modification adopts a low-temperature and low-damage process of magnetron sputtering and sol-gel method: the magnetron sputtering is carried out in a vacuum environment, the target material temperature is controlled at 40 DEG C-60 DEG C, and the carbon fiber tows are uniformly moved to avoid local overheating; the sol-gel method only needs to be dried at 80 DEG C-100 DEG C in a vacuum, without high-temperature sintering. Both processes will not damage the carbon skeleton structure of the carbon fiber, can ensure that the tensile strength retention rate of the modified carbon fiber is greater than or equal to 95%, avoid damaging the core reinforcing performance of the carbon fiber due to the modification process, and provide reliable strength support for the composite material.

[0049] In the application, the parameters of the magnetron sputtering technology are preferably as follows: the vacuum degree is - , the working gas pressure is 0.3 Pa-0.5 Pa; the sputtering power is 280 W-320 W, and the atmosphere is Ar gas; further preferably, the vacuum degree is ~ , the working gas pressure is 0.3 Pa-0.4 Pa; the sputtering power is 280 W-300 W, and the atmosphere is Ar gas.

[0050] The sol-gel method is preferably as follows: aluminum nitrate and citric acid are sequentially added into ethanol, stirred at a speed of 300 r / min-400 r / min for 3 h-4 h under the condition of a constant-temperature water bath at 50 DEG C-60 DEG C to form a transparent and uniform sol, and then aged at room temperature for 24 h-36 h; the pretreated continuous carbon fiber tows are coated by using the immersion-drawing method, the immersion time is 30 s-40 s, then the tows are taken out at a uniform speed of 2 mm / s-3 mm / s, and dried at room temperature for 10 min-15 min; and then dried in a vacuum drying box at 80 DEG C-100 DEG C for 2 h-3 h; wherein the molar ratio of the aluminum nitrate, the citric acid and the ethanol is 1:1.2:8-1:1.5:10.

[0051] The stainless steel foil is polished, and then etched to obtain a standby stainless steel foil;

[0052] The surface of the stainless steel foil is prone to form a dense chromium oxide film and adsorb oil stains, dust and other impurities during production and storage. These substances hinder the direct combination of the stainless steel foil with Al foil and carbon fiber, resulting in gaps or insufficient bonding at the interface. The low-temperature plasma bombardment method is used to polish the stainless steel foil. The physical bombardment of high-energy plasma particles can quickly remove the surface oxide film and loose impurities. The Ar atmosphere can avoid the secondary oxidation of the stainless steel foil during polishing. Compared with the traditional polishing with a hundred-grit cloth, this method does not have mechanical friction residues and does not cause physical scratches or deformation to the ultra-thin stainless steel foil (such as 0.04mm 430SS foil), thereby ensuring the integrity of the foil. The subsequent ultrasonic-assisted electrochemical etching further removes the residual oxide film fragments and small impurities. The surface of the stainless steel foil is cleaned to a state of "no oxidation and no impurities" by the electrochemical effect of dissolving the surface stubborn oxide layer and the ultrasonic cavitation effect of accelerating the detachment of impurities, thereby providing a clean substrate for the subsequent diffusion welding with Al foil and the interface bonding with carbon fiber.

[0053] In addition, the two processing techniques work together to build a controllable nanoscale rough structure on the surface of the stainless steel foil. The ultrasonic-assisted electrochemical etching can accurately form a nanoscale concave-convex structure with Ra of 50nm-100nm on the surface of the stainless steel foil, which greatly increases the surface specific area. The microscopic rough structure can form a "mechanical interlocking" effect with the adjacent Al foil during sintering. Al atoms are more likely to fill into the pits on the surface of the stainless steel foil, forming an anchoring structure to avoid interlayer sliding. At the same time, the physical adsorption area with the modified carbon fiber (surface containing The nanoscale coating) is also increased, the interface gap is reduced, and the interlayer bonding strength is increased by more than 30% (compared with the smooth surface without etching). The low-temperature plasma bombardment polishing can initially roughen the surface, providing a uniform initial surface state for the subsequent formation of "nanoscale concave-convex structure" by electrochemical etching, avoiding uneven etching effect caused by differences in original surface flatness, and ensuring the consistency of batch processing. Further, the low-temperature plasma bombardment can introduce active groups (such as hydroxyl and carboxyl) on the surface of the stainless steel foil and excite the surface atoms to a high-energy state. The subsequent electrochemical etching further exposes the Fe and Cr active atoms inside the stainless steel foil. The activated surface state can significantly improve the diffusion reaction rate of the stainless steel foil and the Al foil during sintering. In the first sintering stage (550℃-650℃), Al atoms are more likely to form stable intermetallic compounds with Fe and Cr atoms on the surface of the stainless steel foil rather than simply physically adhering, thereby upgrading the interface bonding from "physical bonding" to "chemical bonding + physical interlocking" dual bonding mode, and greatly improving the interlayer peel resistance.

[0054] In the present application, the polishing of the stainless steel foil is specifically preferably: the low-temperature plasma bombardment method is used to polish the stainless steel foil, and the parameters of the low-temperature plasma bombardment method are preferably: power 300-350 W, time 2-4 min; further preferably: power 300 W, time 2 min; the atmosphere of the low-temperature plasma bombardment method is Ar gas.

[0055] In the present application, the etching is specifically preferably: the ultrasonic-assisted electrochemical etching process is used to etch the surface of the stainless steel foil to form a nano-scale concave-convex structure.

[0056] In the present application, the ultrasonic-assisted electrochemical etching process is specifically preferably: the stainless steel foil is used as an anode, and a platinum sheet is used as a cathode, and the electrode spacing is controlled to be 30-40 mm; the electrolyte is selected from 0.5-0.8 mol / L of solution, and the electrolyte temperature is 25-30 DEG C; in the etching process, ultrasonic assistance is introduced, the ultrasonic power is 250-300 W, the ultrasonic frequency is 40-50 kHz; the applied direct current density is , after the etching is completed, the stainless steel foil is quickly taken out, washed with deionized water for 3-5 times to remove the residual electrolyte on the surface, then placed in anhydrous ethanol for ultrasonic cleaning for 10-15 min, and finally dried in a vacuum drying oven at 60-80 DEG C for 1-2 h.

[0057] The stainless steel foil and the modified continuous carbon fiber tows are stacked and fixed and sintered in a graphite mold to obtain the Fe / Al layered composite material based on continuous carbon fibers.

[0058] In the present application, the stainless steel foil and the modified continuous carbon fiber tows are stacked in a specific way before sintering to construct a "strong-tough-enhanced" multilayer synergistic structure, break through the performance bottleneck of a single material, and the outer layer 304SS foil provides overall structural support and corrosion protection; 304SS (0.2 mm thick) as the "outer frame" of the stacking unit has excellent mechanical strength and corrosion resistance; compared with the 0.04 mm 430SS foil, the thicker 304SS foil can provide rigid support for the entire composite material to prevent deformation of the stack during sintering due to pressure, and resist external impact, wear and other mechanical effects during the service stage of the material; 304SS contains 18-20% Cr and 8-10.5% Ni, and a dense chromium oxide passivation film can be easily formed on the surface, which can be used as a "corrosion barrier" of the composite material to reduce the contact between the Al foil (which is easily oxidized) and the external corrosive medium and improve the overall environmental stability of the material (such as reducing the corrosion rate by more than 40% in the neutral salt spray test).

[0059] The multi-thin-foil micro unit realizes the precise adaptation of "metal toughness + fiber reinforcement". The multi-thin-foil micro unit is repeatedly stacked in "Al-carbon fiber-430SS foil" (7 layers of Al, 6 layers of carbon fiber, and 6 layers of 430SS in total), forming an alternating structure of "flexibility-reinforcement-rigidity": Al foil (0.04mm 1060 aluminum foil): As a flexible transition layer, it has good plasticity and low density, can buffer stress through deformation when stressed, and avoid brittle fracture caused by stress concentration; at the same time, Al and 430SS can form Fe-Al intermetallic compounds (such as FeAl, ) during sintering, combining the rigidity of 430SS with the toughness of Al to balance the strength and plasticity of the material; the continuous carbon fiber as the core reinforcement is uniformly distributed between Al and 430SS in the stacking direction, and its high strength (tensile strength ≥ 3000MPa) and high modulus characteristics can significantly improve the overall carrying capacity of the composite material, solving the problem of "insufficient strength" of traditional Fe / Al layered materials; and the adaptability of the carbon fiber and the double plating layer ( ) ensures that it is tightly combined with the metal matrix and avoids fiber debonding failure; the 430SS foil (0.04mm) as a rigid spacing layer can limit the excessive flow of Al foil during high-temperature sintering, maintaining the structural integrity of the micro unit; at the same time, 430SS (ferritic stainless steel) and Fe-Al intermetallic compounds have good compatibility, which can further strengthen the interface bonding and avoid interlayer peeling.

[0060] In the present application, the stacking is stacked with 304SS foil-multi-thin-foil micro unit-304SS foil as a stacking unit, and a single sample contains five stacking units, wherein the specific stacking mode of the multi-thin-foil micro unit is: Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al.

[0061] In the present application, the sintering includes a first sintering stage and a second sintering stage. The first sintering stage is: rapidly heating at a heating rate of 100℃ / min, heating to 550℃, then heating to 600-650℃ at a heating rate of 50℃ / min and holding; the second sintering stage is: heating to 850-950℃ at a heating rate of 100℃ / min and holding.

[0062] The present application does not specially limit the holding time after the first sintering stage and the second sintering stage, and the total sintering time can be controlled within 4 hours.

[0063] The present invention also provides an Fe / Al layered composite material based on continuous carbon fibers, wherein the Fe / Al layered composite material based on continuous carbon fibers is obtained by the preparation method described in the above technical solution.

[0064] Example 1

[0065] (1) Raw material preparation

[0066] Continuous carbon fiber tow: T700 grade 12K continuous carbon fiber tow (single filament diameter 7μm, tensile strength 3430MPa) is selected.

[0067] Metal foils: 0.2mm thick 304SS foil (composition: Cr 18.5%, Ni 9.5%, Fe balance, purity ≥99.9%), 0.04mm thick 430SS foil (composition: Cr 17%, Fe balance, purity ≥99.9%), 0.04mm thick 1060 aluminum foil (Al content ≥99.6%).

[0068] Chemical reagents: anhydrous ethanol (purity ≥99.7%), aluminum nitrate (Al(NO3)3・9H2O, purity ≥99%), citric acid ( (Purity ≥ 99.5%), concentrated sulfuric acid (concentration 98%), and deionized water.

[0069] (2) Pretreatment and double-coating modification of continuous carbon fiber bundles

[0070] The T700 continuous carbon fiber bundle was completely immersed in anhydrous ethanol at room temperature (25°C) for 32 minutes. Then it was transferred to fresh anhydrous ethanol and rinsed for 10 minutes to remove dissolved oil and reagent residue. Finally, the bundle was hung to drain for 10 minutes, and the moisture content was controlled to be ≤5% to obtain the pretreated continuous carbon fiber bundle.

[0071] Dual-coating gradient modification:

[0072] Magnetron sputtering of Ni-P alloy transition layer: DC magnetron sputtering equipment was used, with a Ni-P alloy target (Ni 89%, P 11%, purity ≥99.95%) and a target-to-substrate distance of 90 mm; the vacuum chamber was evacuated to... Ar gas with a purity of ≥99.999% was introduced and the working pressure was maintained at 0.4 Pa. The sputtering power was set to 300 W, and the continuous carbon fiber bundle was controlled to move at a constant speed of 6 mm / min. Sputtering was performed for 14 min to deposit an 80 nm thick Ni-P alloy transition layer on the surface of the bundle.

[0073] Sol-gel coating Nanocoating: The sol was prepared by adding aluminum nitrate and citric acid into ethanol in the molar ratio of 1:1.3:9, and stirring at 55°C for 3.5h at a speed of 350r / min. After aging for 30h at room temperature, the carbon fiber tows coated with Ni-P were immersed in the sol for 35s, and then taken out at a speed of 2.5mm / s. The tows were dried at room temperature for 12min, and then dried in a vacuum drying oven at 85°C for 2.5h to form a 35nm-thick nanocoating on the surface of the tows. Nanocoating, and a modified continuous carbon fiber tow with a coating porosity of ≤2.5% was obtained.

[0074] (3) Polishing and etching of stainless steel foil

[0075] Low-temperature plasma bombardment polishing:

[0076] The 0.2mm 304SS foil and the 0.04mm 430SS foil were treated respectively: the low-temperature plasma equipment was used in an Ar atmosphere (flow rate 200mL / min), the power was set to 320W, and the bombardment time was 3min to remove the surface oxide film and loose impurities of the foils and avoid mechanical scratches.

[0077] Ultrasonic-assisted electrochemical etching:

[0078] Two-electrode system was constructed: the polished stainless steel foil was used as the anode, and the platinum sheet (purity ≥99.9%) was used as the cathode, and the electrode spacing was 35mm.

[0079] Electrolyte preparation: 98% concentrated sulfuric acid and deionized water were mixed to prepare a 0.6mol / L H2SO4 solution, and the temperature of the electrolyte was maintained at 28°C.

[0080] Etching parameters: ultrasonic power 280W, frequency 45kHz, and direct current density was applied; the 0.04mm 430SS foil was etched for 3.5min, and the 0.2mm 304SS foil was etched for 5.5min.

[0081] Post-processing: after etching, the foils were rinsed with deionized water for 4 times (30s each time), ultrasonically cleaned with anhydrous ethanol for 12min, and finally dried in a vacuum drying oven at 70°C for 1.5h to obtain the standby stainless steel foil with a surface Ra of 75nm nanometer concave-convex structure.

[0082] (4) Stacking and sintering

[0083] Stacking assembly:

[0084] ​Take "304SS foil - multi-thin foil micro unit - 304SS foil" as a stacking unit, and a single sample contains 5 stacking units; wherein the "multi-thin foil micro unit" is repeatedly stacked 6 times according to "Al foil - modified carbon fiber bundle - 430SS foil" (i.e. Al-carbon fiber-430SS-Al-carbon fiber-430SS-…-Al, a total of 7 layers of Al foil, 6 layers of carbon fiber, and 6 layers of 430SS foil), and the alignment of each layer is ensured during the stacking process without misalignment or wrinkles.

[0085] Fast hot-press sintering:

[0086] The stack is fixed in a graphite mold and placed in a fast hot-press sintering furnace:

[0087] First sintering stage: increase the temperature to 550℃ at a rate of 100℃ / min, then increase the temperature to 620℃ at a rate of 50℃ / min, and keep the temperature for 1.2h, during which a pressure of 6MPa is applied;

[0088] Second sintering stage: increase the temperature to 900℃ at a rate of 100℃ / min, and keep the temperature for 1.2h, during which the pressure is increased to 16MPa;

[0089] After sintering, the furnace is cooled to room temperature to obtain a continuous carbon fiber-based Fe / Al layered composite material (size: 100mm×100mm×5mm).

[0090] Performance and test

[0091] As Figure 1 The actual stacking structure of the multi-thin foil used in the present application is shown in the schematic diagram, and the stacking method and foil selection can ensure the mutual stacking of the foils and the continuous carbon fibers and the rapid sintering and bonding, greatly shorten the material preparation period, greatly improve the yield and mechanical properties, and provide an ideal design idea for its wide application.

[0092] 1. The microstructure and morphology of the continuous carbon fiber-based Fe / Al layered composite material prepared in Example 1 of the present application are observed by SEM, and scanning is performed under secondary electrons (SE) and a test voltage of 20KeV, and EDS area scanning of a typical area is performed to determine the element composition of Example 1 of the present application

[0093] The results are shown in Figure 2 The test data show that the fiber and the sintered matrix are well combined, and the EDS data show that a C / Al-containing compound is newly formed around the continuous carbon fiber, which indicates that the continuous carbon fiber is successfully chemically combined with the matrix and the corresponding transition layer instead of being simply mechanically combined, and this kind of combination method can ensure that the material has excellent strength and hardness during use and avoids premature failure of the material.

[0094] 2. The results of phase analysis of the continuous carbon fiber based Fe / Al layered composite prepared in Example 1 of the present application by XRD. In order to determine the final metal layer, transition layer and newly formed fiber and matrix combined phase, phase analysis was performed by using a Bruker D8 Advance XRD scanner. The scanning data range was: 20-90°, the scanning speed was: 5° / Min, and the specific phase composition was determined according to the corresponding diffraction peak position.

[0095] As shown in the results, it can be found from the corresponding data that the matrix product and transition layer phase exist at (110) and (211) crystal phase, respectively, and the reaction product phase of the continuous fiber and the matrix, i.e., the new phase Al4C3 phase, appears at (012) and (014) two crystal phase families. Figure 3

[0096] 3. The mechanical property test of the continuous carbon fiber based Fe / Al layered composite prepared in Example 1 of the present application by using a universal testing machine. In order to verify the material mechanical properties and stability of Example 1, three-point bending and compressive strength tests were performed. The test was performed by using a MTS Test Works universal testing machine, and three groups of parallel samples were tested in two directions perpendicular to the layer and parallel to the layer for the two bending and compressive tests. Among them, the three-point bending test was tested by using a displacement rate of 0.05mm / Min, and the compressive test was tested by using a displacement rate of 0.5mm / Min. As shown in the results, Figures 4-5 It can be found from the corresponding data that the interfaces of the composite prepared by the process are well metallurgically combined, and the compressive and bending strength performance is excellent. Among them, the compressive strength perpendicular to the layer direction reaches 3019MPa, the bending strength reaches 855MPa, the compressive strength parallel to the layer direction reaches 2090MPa, and the bending strength reaches 687MPa. The failure mechanism of the material is the synergistic effect of micro-crack initiation, continuous carbon fiber pulling and bridging, which finally makes the composite material obtain excellent comprehensive mechanical properties.

[0097] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application. Any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.​

Claims

1. A method for preparing Fe / Al layered composite material based on continuous carbon fibers, characterized in that, Includes the following steps: The continuous carbon fiber bundles were impregnated with alcohol and then pretreated to obtain pretreated continuous carbon fiber bundles. The pretreated continuous carbon fiber bundle is subjected to double-coating gradient modification to obtain the modified continuous carbon fiber bundle. The stainless steel foil is polished and then etched to form a nano-uneven structure, thus obtaining a spare stainless steel foil. The spare stainless steel foil and the modified continuous carbon fiber bundle are stacked and fixed in a graphite mold for sintering to obtain the Fe / Al layered composite material based on continuous carbon fiber. Specifically, the dual-coating gradient modification involves depositing a 50-100 nm Ni-P alloy transition layer on the surface of the pretreated continuous carbon fiber bundle using magnetron sputtering technology, followed by coating a 20-50 nm Al2O3 nano-coating using a sol-gel method. The stacking is performed with 304SS foil-multi-thin foil micro-unit-304SS foil as a stacking unit, and a single sample contains five stacking units. The specific stacking method of the multi-thin foil micro-unit is: Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al-carbon fiber-430SS foil-Al.

2. The method for preparing Fe / Al layered composite material based on continuous carbon fibers according to claim 1, characterized in that, The parameters for alcohol impregnation are as follows: the continuous carbon fiber bundle is placed in ethanol and left to stand for 30-35 minutes; the pretreatment specifically involves: transferring the alcohol-impregnated continuous carbon fiber bundle to new anhydrous ethanol for rinsing to remove dissolved oil and impurities, and finally draining; the stainless steel foil includes 0.04mm 1060 aluminum foil, 0.04mm 430SS foil, and 0.2mm 304SS foil.

3. The method for preparing Fe / Al layered composite material based on continuous carbon fibers according to claim 1, characterized in that, The parameters for the magnetron sputtering technology are: vacuum level of 5 × 10⁻⁶. -4 Pa ~ 8×10 -4 Pa, working gas pressure is 0.3Pa-0.5Pa; sputtering power is 280W-320W, atmosphere is Ar; The sol-gel method specifically involves: adding aluminum nitrate and citric acid sequentially to ethanol, stirring at 300-400 rpm for 3-4 hours under a constant temperature water bath at 50-60℃ to form a transparent and uniform sol, and then allowing it to stand at room temperature for 24-36 hours for aging; coating using an impregnation-coating method, immersing the pretreated continuous carbon fiber bundle into the sol for 30-40 seconds, then uniformly removing it at a lifting speed of 2-3 mm / s, and air-drying it at room temperature for 10-15 minutes; then placing it in a vacuum drying oven and drying it at 80-100℃ for 2-3 hours; wherein the molar ratio of aluminum nitrate:citric acid:ethanol is 1:1.2:8~1:1.5:

10.

4. The method for preparing Fe / Al layered composite material based on continuous carbon fibers according to claim 1, characterized in that, The specific method for polishing the stainless steel foil is as follows: the stainless steel foil is polished using a low-temperature plasma bombardment method. The parameters of the low-temperature plasma bombardment method are: power 300~350W, time 2~4min; the atmosphere of the low-temperature plasma bombardment method is Ar gas.

5. The method for preparing Fe / Al layered composite material based on continuous carbon fibers according to claim 1, characterized in that, The etching process specifically involves using an ultrasonic-assisted electrochemical etching process to etch the surface of a thin stainless steel foil, forming a nanoscale uneven structure.

6. The method for preparing Fe / Al layered composite material based on continuous carbon fibers according to claim 5, characterized in that, The ultrasonic-assisted electrochemical etching process specifically involves: using a stainless steel foil as the anode and a platinum sheet as the cathode, with the electrode spacing controlled at 30mm-40mm; selecting a 0.5mol / L-0.8mol / L H2SO4 solution as the electrolyte, and maintaining an electrolyte temperature of 25℃-30℃; introducing ultrasonic assistance during the etching process, with an ultrasonic power of 250W-300W and an ultrasonic frequency of 40kHz-50kHz; and applying a DC current density of 12mA / cm². 2 -18mA / cm 2 After etching is completed, the stainless steel foil is quickly removed and rinsed with deionized water 3-5 times to remove residual electrolyte on the surface. Then it is ultrasonically cleaned in anhydrous ethanol for 10-15 minutes and finally dried in a vacuum drying oven at 60℃-80℃ for 1-2 hours.

7. The method for preparing Fe / Al layered composite material based on continuous carbon fibers according to claim 1, characterized in that, The sintering includes a first sintering stage and a second sintering stage. The first sintering stage is: rapidly heating to 550°C at a heating rate of 100°C / min, and then heating to 600°C-650°C at a heating rate of 50°C / min and holding at that temperature. The second sintering stage is: heating to 850°C-950°C at a heating rate of 100°C / min and holding at that temperature.

8. A Fe / Al layered composite material based on continuous carbon fibers, characterized in that, The Fe / Al layered composite material based on continuous carbon fibers is obtained by the preparation method according to any one of claims 1 to 7.

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