Memory alloy fiber reinforced aluminum alloy crack self-healing repair equipment and method

Abstract

The invention belongs to the field of self-healing repair of metal matrix composites, and discloses self-healing repair equipment and method for memory alloy fiber reinforced aluminum alloy cracks. The memory alloy fibers are doped into the aluminum alloy material, so that the overall strength and toughness of the material can be enhanced, and local stress in the material is relieved to prevent generation and expansion of microcracks. A memory alloy filament penetrating through the material is laid in the main force bearing direction of the material, and the filament is externally connected with a current control system to monitor the internal crack expansion condition. And when an electric signal received by a current control system reaches a threshold value, current is supplied to the memory alloy filaments with abnormal electric signals for rapid heating, the shape memory effect is activated, the original macroscopic geometrical shape of the material is recovered, and the cracks are drawn to achieve reset alignment. And then the crack area is rapidly heated through high-frequency induction heating equipment, crack welding is completed along with softening, permeation and solidification of eutectic in the material, and finally crack self-healing repair is achieved.

Description

Technical Field

[0001] The present invention relates to the field of metal-based composite materials with high efficiency and good repair effect, and in particular to a self-healing repair device and method for cracks in a memory alloy fiber-reinforced aluminum alloy. Background Art

[0002] With the continuous improvement of material performance requirements in modern industry, especially in the fields of aerospace, automobile manufacturing, energy equipment, etc., metal materials often face the problem of cracks or structural failure due to fatigue, corrosion, mechanical damage, etc. during long-term use. After cracks appear inside metal components, they usually need to be repaired or replaced manually for safety reasons, which not only increases maintenance costs, but also may bring the risk of production downtime or equipment downtime. The use of components with self-healing materials is expected to reduce the time of system downtime inspection and maintenance, and reduce the cost of failure. The most common technology for self-healing materials is to disperse liquid adhesive capsules into the material. When cracks form and destroy the capsules, the adhesive will penetrate into the cracks, react with catalysts or air, and bond the cracks together. However, the liquid in the capsule cannot carry the structural load, which reduces the initial strength of the original material. In addition, since the liquid cannot carry the load, it causes stress concentration and potential crack initiation points. The healing agent penetrates into the cracks and then solidifies, and may solidify when the structure is deformed. This means that if the crack deformation is too large and causes structural failure, self-healing will be meaningless at this time. Additionally, the adhesive is consumed during the self-healing process, which means that only a limited amount of damage can be healed over time, and holes are left behind as the adhesive is consumed, which can create stress concentrations and potential crack initiation sites.

[0003] The present invention uses nickel-titanium shape memory alloy fibers to enhance material strength and inhibit crack generation and expansion. After a crack is formed, as the crack pulls the nickel-titanium memory alloy filament, the equipment connected to both sides will capture the change of the current signal passing through it. After reaching the threshold, the self-healing repair process will be started. First, the shape memory effect of the nickel-titanium memory alloy is activated by the Joule heat of the current, the original macroscopic geometry of the sample is restored, and the crack is pulled together to achieve reset alignment. Subsequently, the crack site is fixedly heated by a high-frequency induction heating device to melt the eutectic in the matrix alloy. As the molten eutectic material diffuses and solidifies, the crack is welded and the crack self-healing repair is achieved. Summary of the invention

[0004] The purpose of the present invention is to provide a memory alloy fiber reinforced aluminum alloy crack self-healing repair equipment and method to solve the problem of rapid and high-quality self-healing repair of internal cracks in aluminum alloy materials.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A memory alloy fiber reinforced aluminum alloy crack self-healing repair equipment and method, wherein both ends of the nickel-titanium memory alloy filament in the aluminum alloy self-healing material are connected to a current control system; two induction coils are placed in series on both sides of the direction of the nickel-titanium memory alloy filament in the self-healing material, and connected to a variable frequency power supply; the current control system is connected to the variable frequency power supply and controls the generation of high-frequency alternating current;

[0007] The aluminum alloy self-healing material comprises an aluminum alloy matrix, nickel-titanium memory alloy fibers, and nickel-titanium memory alloy filaments;

[0008] The nickel-titanium memory alloy fibers are evenly distributed in the aluminum alloy matrix, and the nickel-titanium memory alloy filaments are parallel to each other and tightly combined with the aluminum alloy matrix and penetrate therein.

[0009] Preferably, the specific preparation process includes the following steps:

[0010] Step 1: Select the appropriate size and quantity of nickel-titanium memory alloy fibers and nickel-titanium memory alloy filaments, use a rust remover to corrode and remove the titanium dioxide inert oxide layer on the surface of the alloy material in a nitrogen atmosphere, and then evenly apply flux on the surface to prevent oxidation;

[0011] Step 2: Melt the aluminum ingot and an appropriate amount of silicon or copper at high temperature, stir the molten alloy with a graphite stirrer for several minutes to ensure uniform mixing, and form a molten aluminum alloy matrix containing an aluminum-silicon or aluminum-copper eutectic system.

[0012] Step three, adding an appropriate amount of short and thin nickel-titanium alloy fibers processed in step one into the molten aluminum alloy matrix processed in step two and stirring for ten minutes using a graphite stirrer to evenly disperse the fibers in the matrix.

[0013] Step 4: Arrange the nickel-titanium memory alloy filaments processed in step 1 in parallel and apply a small amount of tensile elastic deformation to fix them in the mold, pour the molten fiber-containing composite aluminum alloy into the mold, and form a self-healing metal-based composite material after solidification.

[0014] Step 5: Connect the nickel-titanium memory alloy filaments extending out of the base material on both sides to a current control system. The current control system sends out electrical signals in real time through the nickel-titanium memory alloy filaments to monitor the crack propagation inside the material.

[0015] Preferably, the specific self-healing repair process includes the following steps:

[0016] Step 1: After microcracks appear in the self-healing material, the nickel-titanium shape memory alloy fibers dispersed therein inhibit the expansion of the microcracks;

[0017] Step 2: The crack continues to extend to the nickel-titanium memory alloy filament, the extension is inhibited, and the alloy filament at the crack gap is tensilely deformed;

[0018] Step 3: The current control system continuously monitors the microcurrent signal flowing through each nickel-titanium memory alloy filament, and when the microcurrent signal reaches a threshold, current is passed through the corresponding nickel-titanium memory alloy filament;

[0019] Step 4: The nickel-titanium memory alloy filament activates the shape memory effect due to the Joule heat generated by the current, pulling the crack to restore the original geometric shape of the sample, and realizing the macroscopic resetting and closure of the crack;

[0020] Step five: the current control system controls the variable frequency power supply to generate high-frequency alternating current to flow through the induction coil, and moves the induction coil to the nickel-titanium memory alloy filament where the electrical signal is abnormal. Eddy currents are formed in the matrix between the two coils, thereby generating heat rapidly. The eutectic melts and diffuses into the crack, completing the welding of the crack, and the crack self-healing repair is completed.

[0021] The beneficial effects of the present invention are:

[0022] The entire self-healing aluminum alloy material structure of the present invention is solid, and each part of the material can bear the load. The superelasticity and stress deformation ability of the dispersed shape memory alloy fiber can effectively enhance the overall strength and toughness, and relieve the local stress in the material to prevent the generation and expansion of micro cracks. The nickel-titanium memory alloy filaments stretched due to crack expansion are quickly locked by electrical signals, and the memory alloy filaments are quickly heated by current to complete the macroscopic position alignment of the cracks. Subsequently, the aluminum alloy matrix is ​​heated by high-frequency electromagnetic induction equipment, and the eutectic part is softened and melted into the cracks to complete the welding of the cracks, thereby achieving rapid, accurate, and high-quality self-healing repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a memory alloy fiber reinforced aluminum alloy crack self-healing repair equipment provided by the present invention;

[0024] Figure 2 This is a preparation flow chart of a memory alloy fiber reinforced aluminum alloy crack self-healing material provided by the present invention;

[0025] Figure 3 This is a flow chart of a method for self-healing and repairing cracks in a memory alloy fiber reinforced aluminum alloy provided by the present invention;

[0026] The numbers in the figure are: 1. Aluminum alloy self-healing material; 2. Aluminum alloy matrix; 3. Nickel-titanium memory alloy fiber; 4. Nickel-titanium memory alloy filament; 5. Induction coil; 6. Current control system; 7. Variable frequency power supply. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0028] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In this embodiment, Figure 1 As shown, both ends of the nickel-titanium memory alloy filaments in the aluminum alloy self-healing material are connected to the current control system, and two induction coils are placed in series on both sides of the direction of the nickel-titanium memory alloy filaments in the self-healing material and connected to the variable frequency power supply. The current control system is connected to the variable frequency power supply and controls the generation of high-frequency alternating current. Among them, the aluminum alloy self-healing material includes an aluminum alloy matrix, nickel-titanium memory alloy fibers, and nickel-titanium memory alloy filaments; the nickel-titanium memory alloy fibers are evenly distributed in the aluminum alloy matrix, and the nickel-titanium memory alloy filaments are parallel to each other and closely combined with the aluminum alloy matrix and penetrate it.

[0030] Specifically, Figure 2 As shown, the specific material preparation process includes: using a 4.8% HF-10.5% HNO3 solution to corrode a number of nickel-titanium memory alloy short fibers with a diameter of 0.05 mm and a nickel-titanium memory alloy filament with a diameter of 0.9 mm in a nitrogen atmosphere to remove the titanium dioxide inert oxide layer on the surface of the material, and then immersing the nickel-titanium memory alloy material in a phosphate-based flux to ensure cleanliness, good wettability and prevent the formation of an oxide layer. The aluminum ingot and an appropriate amount of silicon ingot are melted at high temperature to form an aluminum-silicon alloy, in which the mass fraction of silicon is 3%, to form a molten aluminum alloy matrix containing an aluminum-silicon eutectic system. Then, an appropriate amount of the previously treated nickel-titanium memory alloy fiber is added to the molten aluminum alloy matrix, and a graphite stirrer is used to stir for 10 minutes to ensure that the fiber is evenly dispersed in the matrix. Several treated nickel-titanium memory alloy filaments are arranged in parallel on the mold, and a small amount of tensile elastic deformation is applied, and the molten fiber-containing composite aluminum alloy is poured into the mold, and a self-healing metal-based composite material is formed after solidification. Finally, the nickel-titanium memory alloy filaments extending out of the base material on both sides are connected to a current control system. The current control system sends out electrical signals in real time through the nickel-titanium memory alloy filaments to monitor the expansion of cracks inside the material.

[0031] Specifically, Figure 3As shown, the specific self-healing process includes that after microcracks appear inside the memory alloy fiber reinforced aluminum alloy self-healing material, they are first pulled by the thin and short memory alloy fibers dispersed in the material to inhibit the further expansion of the microcracks. When the microcracks further expand to the memory alloy filaments, the nickel-titanium memory alloy filaments in this area are tensilely deformed. Since each filament is externally connected to a current control system and a weak current feedback state is passed through it, the cross-sectional area decreases when it is pulled, resulting in fluctuations in parameters such as resistance. The crack tolerance is set according to the actual working conditions. When the current control system monitors that the electrical signal reaches a certain threshold, current is passed through the filament with abnormal electrical signal. Joule heat causes the filament temperature to rise, activating the shape memory effect. As the shape of the nickel-titanium memory alloy filaments is restored, the cracks are pulled together to achieve reset, alignment, and closure, and the original macroscopic geometric shape of the sample is restored. Then the current control system controls the variable frequency power supply to turn on, and the coil moves to the area of ​​nickel-titanium memory alloy filaments where the electrical signal is abnormal. High-frequency alternating current passes through the coil to generate an alternating magnetic field. The aluminum alloy matrix in the alternating magnetic field will generate eddy currents and heat up rapidly. The eutectic inside the matrix softens and melts into the aligned closed cracks and microcracks, realizing crack welding and completing the crack self-healing repair process.

[0032] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A self-healing repair equipment and method for memory alloy fiber reinforced aluminum alloy cracks, characterized in that: include: Both ends of the nickel-titanium memory alloy filament (4) in the aluminum alloy self-healing material (1) are connected to a current control system (6); two induction coils (5) are placed in series on both sides of the direction of the nickel-titanium memory alloy filament (4) in the self-healing material, and are connected to a variable frequency power supply (7); the current control system (6) is connected to the variable frequency power supply (7) and controls the generation of high-frequency alternating current; The aluminum alloy self-healing material (1) comprises an aluminum alloy matrix (2), a nickel-titanium memory alloy fiber (3), and a nickel-titanium memory alloy filament (4); The nickel-titanium memory alloy fibers (3) are evenly distributed in the aluminum alloy matrix (2), and the nickel-titanium memory alloy filaments (4) are parallel to each other and tightly combined with the aluminum alloy matrix (2) and penetrate therein.

2. The memory alloy fiber reinforced aluminum alloy crack self-healing repair equipment and method according to claim 1, characterized in that: The specific preparation process includes the following steps: Step 1: Use a rust remover to corrode and remove the titanium dioxide inert oxide layer on the surface of the nickel-titanium memory alloy material in a nitrogen atmosphere, and then evenly apply flux to the surface to prevent oxidation; Step 2: Melt the aluminum ingot and an appropriate amount of silicon or copper at high temperature, stir the molten alloy with a graphite stirrer for several minutes to ensure uniform mixing, and form a molten aluminum alloy matrix containing an aluminum-silicon or aluminum-copper eutectic system. Step three, adding an appropriate amount of short and thin nickel-titanium alloy fibers processed in step one into the molten aluminum alloy matrix processed in step two and stirring for ten minutes using a graphite stirrer to evenly disperse the fibers in the matrix. Step 4: Arrange the nickel-titanium memory alloy filaments processed in step 1 in parallel and apply a small amount of tensile elastic deformation to fix them in the mold, pour the molten fiber-containing composite aluminum alloy into the mold, and form a self-healing metal-based composite material after solidification. Step 5: Connect the nickel-titanium memory alloy filaments (4) extending out of the base material on both sides to a current control system (6) to monitor the crack propagation inside the material.

3. The memory alloy fiber reinforced aluminum alloy crack self-healing repair equipment and method according to claim 1, characterized in that: The specific self-healing repair process includes the following steps: Step 1: After microcracks appear in the self-healing material, the nickel-titanium shape memory alloy fibers (3) dispersed therein inhibit the expansion of the microcracks; Step 2: the crack continues to extend to the nickel-titanium memory alloy filament (4), the extension is inhibited, and the alloy filament at the crack gap is tensilely deformed; Step 3, the current control system (6) continuously monitors the microcurrent signal flowing through each nickel-titanium memory alloy filament (4), and when the microcurrent signal reaches a threshold value, current is passed through the corresponding nickel-titanium memory alloy filament (4); Step 4: The nickel-titanium memory alloy filament (4) activates the shape memory effect due to the Joule heat generated by the current, pulling the crack to restore the original geometric shape of the sample, thereby achieving macroscopic resetting and closure of the crack; Step five, the current control system (6) controls the variable frequency power supply (7) to generate a high-frequency alternating current to flow through the induction coil, and the induction coil is moved to the nickel-titanium memory alloy filament where the electrical signal is abnormal. Eddy currents are formed in the matrix between the two coils, thereby rapidly generating heat, and the eutectic melts and diffuses into the crack, completing the welding of the crack, and the crack self-healing repair is completed.

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