TC4 titanium alloy and carbon fiber reinforced composite material laser welding method

Abstract

The invention discloses a TC4 titanium alloy and carbon fiber reinforced composite material laser welding method, and relates to the field of dissimilar material laser welding. The preparation method comprises the following steps: firstly, carrying out surface modification on carbon fibers by using hydrogen peroxide, deepening the surface oxidation depth by microwave radiation, stripping graphene oxide on the outermost surface by ultrasonic treatment, and then carrying out plasma beam treatment impact to increase and enlarge grooves and pores on the surfaces of the carbon fibers, so that active groups and concave-convex structures on the surfaces of the modified carbon fibers after resin is filled and cured; and secondly, a layer of nano nickel is chemically deposited on the surface of the titanium alloy microstructure, permeation and corrosion of the modified carbon nanotubes to the titanium alloy are reduced, then the carbon nanotubes subjected to acid treatment are deposited on the surface layer of the nano nickel through the electrophoretic deposition technology, the interface wetting and spreading capacity is improved, and the residual stress after welding is reduced. The TC4 titanium alloy, the nano nickel deposition layer, the modified carbon nanotube deposition layer and the modified carbon fiber composite material layer are combined and connected through laser welding, so that the high-strength connection effect is achieved.

Description

Technical Field

[0001] The invention relates to the field of laser welding of dissimilar materials, and in particular to a laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material. Background Art

[0002] Carbon fiber composite reinforced material (CFRP for short) is a new type of lightweight material with high specific strength, high modulus and low linear expansion coefficient. It has been applied in national key fields such as aerospace and military products. At the same time, it has gradually become the mainstream direction in civilian fields such as building restoration, F1 racing, rowing, and sports goods. Carbon fiber reinforced composite materials have a very obvious weight reduction effect on automotive structural parts, and also have good impact resistance and energy absorption capacity. However, carbon fiber reinforced composite materials have high production costs, complex manufacturing processes and low fracture toughness. At present, more people choose to connect them with metal materials to form a composite structure, which can give full play to the respective advantages of metal materials and carbon fiber reinforced composite materials.

[0003] Titanium alloy is a high-quality alloy with high strength, low density, good corrosion resistance and high temperature resistance. It has begun to be widely used in various special environments, such as aerospace, military aircraft, large ships and other fields. It is an important material for manufacturing aircraft engines, rockets and high-speed aircraft.

[0004] Laser welding is a precision welding method with small heat source, high precision, fast welding speed and high energy density. Laser welding of titanium alloy and carbon fiber reinforced composite material realizes connection by locally melting titanium alloy and CFRP and then solidifying them by laser heat conduction. However, there is a great difference in thermophysical form between titanium alloy and CFRP, and there is a large residual stress near the welding joint, which reduces the connection strength. Surface treatment of titanium alloy is the main measure to improve the connection strength of titanium alloy and CFRP joint. The surface treatment methods of titanium alloy plates can be divided into three categories: one is surface mechanical treatment such as sandblasting, shot peening, etc.; the second is chemical treatment such as titanium alloy surface anodizing, etc.; the third is to increase the connection interface layer such as plasma spraying, etc. The above methods can improve the connection strength of titanium alloy and CFPR, but they all have certain limitations, and cannot solve the large welding residual stress and poor interface wetting and spreading caused by the difference in thermophysical properties between titanium alloy and CFRP, and the process is complicated and cumbersome. Therefore, there is a need for a method that is efficient, fast and stable and can reduce the residual stress of titanium alloy and CFRP welding. Based on this, the present invention proposes a new laser welding method of TC4 titanium alloy and carbon fiber composite material. Summary of the invention

[0005] The purpose of the present invention is to provide a laser welding method for TC4 titanium alloy and carbon fiber reinforced composite material to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material, comprising the following preparation steps:

[0007] (1) The carbon fiber tow with T700 and 24K warp and weft yarns is immersed in hydrogen peroxide for modification; the mixed solution is sealed and placed in a vacuum drying oven for reaction at 80-120°C for 10 minutes; after the reaction is completed, the mixed solution is cooled to room temperature, the solid is filtered and washed with deionized water for 3 times to remove the residue, and the oxidized carbon fiber is obtained; the oxidized carbon fiber is then immersed in distilled water for microwave irradiation; the microwave irradiation conditions are set to 2.45GHz, 600W, and the treatment time is 60-200s; after the treatment, it is cooled to room temperature and then ultrasonicated at 40-60kHz for 30-60min; after the ultrasonication, the solid is washed with deionized water 3 times, and then dried in a drying oven at 50°C for 6h; finally, the dried carbon fiber is subjected to plasma treatment at a power of 100-140W for 10-60s, and the plasma is H2O, and the modified carbon fiber is obtained after the treatment;

[0008] (2) 3-4 parts of dimethylformamide, 2-4 parts of ethyl acetate, 4-5 parts of polyamide, and 0.1-0.5 parts of a surfactant are mixed and stirred at 60 rpm for 10 min to prepare a sizing solution; the sizing solution is evenly applied to the surface of the modified carbon fiber obtained, and then dried at a drying temperature of 120° C. for 1 min; after the first sizing is completed, the above operation is repeated for a second sizing until the volume ratio of the outer layer resin to the inner layer carbon fiber is 1:1-1.2, and then cured at 120° C. for 5 h. After the curing is completed, a carbon fiber composite material is obtained;

[0009] (3) Using a 1030 nm nanosecond pulsed fiber laser with a beam diameter of 30 μm, a laser power of 70 W, and a scanning speed of 700 mm / s, a row of stripe microtextures were prepared on the surface of a TC4 titanium alloy plate. Each microtexture was spaced 100 μm apart, and the stripe pattern had a width of 100 μm and a depth of 100 μm. The titanium alloy plate was used as two electrodes and placed in acetone / ethanol (v / v = 1:1) to remove surface contaminants. The titanium alloy plate after decontamination was subjected to chemical nickel plating at a rate of 1-3 dm per liter of plating solution. 2 ratio, and the plating time is 1h to obtain a nickel-titanium alloy plate; finally, the carbon nanotube layer on the surface of the nickel layer is obtained by electrophoretic deposition in a carbon nanotube suspension at a working distance of 15mm between two electrodes and a working voltage of 50V for 5min; the deposited titanium alloy plate and the carbon fiber composite material are overlapped together, and then laser welded to obtain a titanium alloy and carbon fiber reinforced composite material.

[0010] Furthermore, the concentration of hydrogen peroxide in step (1) is 1-3%.

[0011] Furthermore, in the step (1), the solid-to-liquid ratio of the carbon fiber tow plain weave to the hydrogen peroxide is 1:3.

[0012] Furthermore, in the step (1), the solid-to-liquid ratio of the oxidized carbon fiber to distilled water is 1:3.

[0013] Furthermore, the plasma treatment in step (1) is pulsed plasma treatment.

[0014] Furthermore, the surfactant in step (2) is Tween 60.

[0015] Furthermore, in step (2), the sizing speed is 1 m / min.

[0016] Furthermore, the composition of the plating solution in step (3) is: 2.5-3.0% NiSO4·6H2O, 3-3.4% NaH2PO2·H2O, 1.3-1.7% NaAC·3H2O, 2.6-3.0% C3H6O3, 0.01% Pb2+, and the rest is deionized water, and the temperature is 90°C.

[0017] Furthermore, the method for preparing the carbon nanotube suspension in step (3) is as follows: acid-treating the carbon nanotubes, acidifying the carbon nanotubes with a HNO3 / H2SO4 (v / v=1:3) mixed solution at 80°C for 2h; washing the mixture with deionized water until neutral, vacuum filtering it with a microporous membrane with a pore size of 0.45μm, and then freeze-drying it at -40°C for 2h to obtain carboxylic acid functionalized carbon nanotubes; finally, dispersing the carbon nanotubes in ethanol to prepare a 1 mg / mL suspension, and adding 0.01-0.15 times the mass of the suspension Mg(NO3)2·6H2O to improve the conductivity of the suspension.

[0018] Furthermore, the laser welding parameters in step (3) are 0.6 kW laser power, 0.8 m / min scanning speed, and 0.95 m spot diameter.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0020] The present invention combines TC4 titanium alloy, nano nickel deposition layer, modified carbon nanotube deposition layer and modified carbon fiber composite material layer and connects them through laser welding to achieve a high-strength connection effect.

[0021] First, the surface of the carbon fiber is modified by hydrogen peroxide, and the hydroxyl radicals and oxygen radicals decomposed by hydrogen peroxide react with the carbon fiber to perform stripping and etching, so as to prepare carbon fiber with graphene oxide on the surface, and then further deepen the surface oxidation depth of the carbon fiber by microwave radiation, and at the same time, the graphene oxide that is not firmly attached can be stripped; then, the conditions of ultrasonic treatment are controlled so that the graphene oxide on the surface is partially stripped, and after plasma beam treatment and impact, the graphite crystals with large crystal size and relatively dense arrangement in the carbon fiber cortex are further broken, and the grooves and pores on the surface of the carbon fiber are increased and expanded, so that the active groups and concave-convex structures on the surface of the modified carbon fiber after subsequent resin filling and curing, physical interlocking and chemical bonding complement each other, and achieve higher bonding strength, thereby improving the strength of the carbon fiber composite material;

[0022] Secondly, a layer of nano-nickel is first chemically deposited on the micro-textured surface of the titanium alloy, and then the acid-treated carbon nanotubes are deposited on the surface of the nano-nickel by electrophoretic deposition technology; the carboxyl protons at the edge of the modified carbon nanotubes are replaced by nickel elements to form a dipole moment, thereby improving the interfacial wetting and spreading ability and reducing the residual stress after welding the titanium alloy and the carbon fiber composite material; the nano-nickel reacts and combines with the titanium metal at high temperature to form an alloy on the contact surface, thereby reducing the penetration and corrosion of the modified carbon nanotubes on the titanium alloy, improving the toughness between the composite materials and forming a multifunctional intercalated self-supporting structure; finally, the treated titanium alloy and the carbon fiber reinforced composite material are welded together by laser to prepare a micro-texture on the surface of the titanium alloy, increase the mechanical bite force between the titanium alloy and the carbon fiber composite material, and improve the connection strength. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the various index testing methods of a TC4 titanium alloy and carbon fiber reinforced composite material prepared in the following examples are as follows:

[0025] Connection strength: The size is 50×30×4mm 3 The embodiments and comparative examples were tested for stress by a universal testing machine. Each embodiment and comparative example was tested 3 times, and the average value of the results was taken as the connection strength of the sample.

[0026] Example 1; (1) A carbon fiber tow plain weave with T700 and 24K warp and weft yarns was immersed in 1% hydrogen peroxide for modification, and the solid-liquid ratio of the carbon fiber tow plain weave to hydrogen peroxide was 1:3; the mixed solution was sealed and placed in a vacuum drying oven, and reacted at 80°C for 10 minutes; after the reaction, the mixture was cooled to room temperature, and the solid was filtered to obtain the solid, and the mixture was washed with deionized water for 3 times to remove the residue, so as to obtain oxidized carbon fiber; the oxidized carbon fiber was then immersed in distilled water, and the oxidized carbon fiber was The solid-liquid ratio of fiber and distilled water was 1:3, and microwave irradiation was performed; the microwave irradiation conditions were set to 2.45GHz, 600W, and the treatment time was 60s; after the treatment, it was cooled to room temperature and then ultrasonicated at 40kHz for 30min; after the ultrasonication, the solid was washed with deionized water for 3 times, and then dried in a drying oven at 50°C for 6h; finally, the dried carbon fiber was treated with isopulse plasma at a power of 100W, a time of 10s, and an ion body of H2O, and modified carbon fiber was obtained after the treatment;

[0027] (2) 3 parts of dimethylformamide, 2 parts of ethyl acetate, 4 parts of polyamide, and 0.1 parts of Tween 60 were mixed and stirred at 60 rpm for 10 min to prepare a sizing solution; the sizing solution was evenly applied to the surface of the modified carbon fiber obtained at a sizing speed of 1 m / min, and dried after the application, with a drying temperature of 120° C. and a drying time of 1 min; after the first sizing was completed, the above operation was repeated for a second sizing until the volume ratio of the outer layer resin to the inner layer carbon fiber was 1:1, and then cured at 120° C. for 5 h, and a carbon fiber composite material was obtained after the curing was completed;

[0028] (3) Using a 1030 nm nanosecond pulsed fiber laser with a beam diameter of 30 μm, a laser power of 70 W, and a scanning speed of 700 mm / s, a row of stripe microtextures were prepared on the surface of a TC4 titanium alloy plate. Each microtexture was spaced 100 μm apart, and the stripe pattern had a width of 100 μm and a depth of 100 μm. The titanium alloy plate was used as two electrodes and placed in acetone / ethanol (v / v = 1:1) to remove surface contaminants. The titanium alloy plate after decontamination was subjected to chemical nickel plating at a rate of 1 dm per liter of plating solution. 2The composition of the plating solution is as follows: 2.5% NiSO4·6H2O, 3% NaH2PO2·H2O, 1.3% NaAC·3H2O, 2.6% C3H6O3, 0.01% Pb2+, and the rest is deionized water. The temperature is 90°C and the plating time is 1h to obtain a nickel-titanium alloy plate; the carbon nanotubes are acidified by using a HNO3 / H2SO4 (v / v=1:3) mixed solution at 80°C for 2h; the mixture is washed with deionized water until neutral, and then vacuum filtered with a microporous membrane with a pore size of 0.45μm, and then freeze-dried at -40°C for 2h to obtain carboxylic acid-functionalized carbon nanotubes; finally, Carbon nanotubes were dispersed in ethanol to prepare a 1 mg / mL suspension, and Mg(NO3)2·6H2O (0.01 times the mass of the suspension) was added to improve the conductivity of the suspension to prepare a carbon nanotube suspension; finally, the carbon nanotube layer on the surface of the nickel layer was obtained by electrophoretic deposition in the carbon nanotube suspension at a working distance of 15 mm between two electrodes and a working voltage of 50 V for 5 minutes; the deposited titanium alloy plate and the carbon fiber composite material were overlapped together, and then laser welded. The laser welding parameters were 0.6 kW laser power, 0.8 m / min scanning speed, and 0.95 m spot diameter to obtain a titanium alloy and carbon fiber reinforced composite material.

[0029] Example 2: (1) A carbon fiber tow plain weave with T700 and 24K warp and weft yarns was immersed in 2% hydrogen peroxide for modification, and the solid-liquid ratio of the carbon fiber tow plain weave to hydrogen peroxide was 1:3; the mixed solution was sealed and placed in a vacuum drying oven, and reacted at 100°C for 10 minutes; after the reaction, the mixture was cooled to room temperature, and the solid was filtered to obtain the solid, and the mixture was washed with deionized water for 3 times to remove the residue, so as to obtain oxidized carbon fiber; the oxidized carbon fiber was then immersed in distilled water, and the oxidized carbon fiber was The solid-liquid ratio of fiber and distilled water was 1:3, and microwave irradiation was performed; the microwave irradiation conditions were set to 2.45 GHz, 600 W, and the treatment time was 130 s; after the treatment, it was cooled to room temperature and then ultrasonicated at 50 kHz for 45 min; after the ultrasonication, the solid was washed with deionized water for 3 times, and then dried in a drying oven at 50°C for 6 h; finally, the dried carbon fiber was subjected to isopulse plasma treatment with a power of 120 W, a time of 35 s, and a plasma of H2O, and modified carbon fiber was obtained after the treatment;

[0030] (2) 3.5 parts of dimethylformamide, 3 parts of ethyl acetate, 4.5 parts of polyamide, and 0.3 parts of Tween 60 were mixed and stirred at 60 rpm for 10 min to prepare a sizing solution; the sizing solution was evenly applied to the surface of the modified carbon fiber obtained at a sizing speed of 1 m / min, and dried after the application, with a drying temperature of 120° C. and a drying time of 1 min; after the first sizing was completed, the above operation was repeated for a second sizing until the volume ratio of the outer layer resin to the inner layer carbon fiber was 1:1.1, and then cured at 120° C. for 5 h, and a carbon fiber composite material was obtained after the curing;

[0031] (3) Using a 1030 nm nanosecond pulsed fiber laser with a beam diameter of 30 μm, a laser power of 70 W, and a scanning speed of 700 mm / s, a row of stripe microtextures were prepared on the surface of a TC4 titanium alloy plate. Each microtexture was spaced 100 μm apart, and the stripe pattern had a width of 100 μm and a depth of 100 μm. The titanium alloy plate was used as two electrodes and placed in acetone / ethanol (v / v = 1:1) to remove surface contaminants. The titanium alloy plate after decontamination was subjected to chemical nickel plating at a rate of 2 dm per liter of plating solution. 2 The composition of the plating solution is as follows: 2.75% NiSO4·6H2O, 3.2% NaH2PO2·H2O, 1.5% NaAC·3H2O, 2.8% C3H6O3, 0.01% Pb2+, and the rest is deionized water. The temperature is 90°C and the plating time is 1h to obtain a nickel-titanium alloy plate; the carbon nanotubes are acidified by using a HNO3 / H2SO4 (v / v=1:3) mixed solution at 80°C for 2h; the mixture is washed with deionized water until neutral, and then vacuum filtered with a microporous membrane with a pore size of 0.45μm, and then freeze-dried at -40°C for 2h to obtain carboxylic acid-functionalized carbon nanotubes; finally, A suspension of 1 mg / mL was prepared by dispersing carbon nanotubes in ethanol, and 0.08 times the mass of the suspension was added with Mg(NO3)2·6H2O to improve the conductivity of the suspension to prepare a carbon nanotube suspension; finally, the carbon nanotube layer on the surface of the nickel layer was obtained by electrophoretic deposition in the carbon nanotube suspension at a working distance of 15 mm between two electrodes and a working voltage of 50 V for 5 minutes; the deposited titanium alloy plate and the carbon fiber composite material were overlapped together, and then laser welded with the laser welding parameters of 0.6 kW laser power, 0.8 m / min scanning speed, and 0.95 m spot diameter to obtain a titanium alloy and carbon fiber reinforced composite material.

[0032] Example 3: (1) A carbon fiber tow plain weave with T700 and 24K warp and weft yarns was immersed in 3% hydrogen peroxide for modification, and the solid-liquid ratio of the carbon fiber tow plain weave to hydrogen peroxide was 1:3; the mixed solution was sealed and placed in a vacuum drying oven, and reacted at 120°C for 10 minutes; after the reaction, the mixture was cooled to room temperature, and the solid was filtered to obtain the solid, and the mixture was washed with deionized water for 3 times to remove the residue, so as to obtain oxidized carbon fiber; the oxidized carbon fiber was then immersed in distilled water, and the oxidized carbon fiber was The solid-liquid ratio of fiber and distilled water was 1:3, and microwave irradiation was performed; the microwave irradiation conditions were set to 2.45GHz, 600W, and the treatment time was 200s; after the treatment, it was cooled to room temperature and then ultrasonicated at 60kHz for 60min; after the ultrasonication, the solid was washed with deionized water for 3 times, and then dried in a drying oven at 50°C for 6h; finally, the dried carbon fiber was subjected to isopulse plasma treatment with a power of 140W, a time of 60s, and a plasma of H2O, and modified carbon fiber was obtained after the treatment;

[0033] (2) 4 parts of dimethylformamide, 4 parts of ethyl acetate, 5 parts of polyamide, and 0.5 parts of Tween 60 were mixed and stirred at 60 rpm for 10 min to prepare a sizing solution; the sizing solution was evenly applied to the surface of the modified carbon fiber obtained at a sizing speed of 1 m / min, and dried after the application, with a drying temperature of 120° C. and a drying time of 1 min; after the first sizing was completed, the above operation was repeated for a second sizing until the volume ratio of the outer layer resin to the inner layer carbon fiber was 1:1.2, and then cured at 120° C. for 5 h, and a carbon fiber composite material was obtained after the curing was completed;

[0034] (3) Using a 1030 nm nanosecond pulsed fiber laser with a beam diameter of 30 μm, a laser power of 70 W, and a scanning speed of 700 mm / s, a row of stripe-shaped micro-textures were prepared on the surface of a TC4 titanium alloy plate. Each micro-texture was spaced 100 μm apart, and the stripe pattern had a width of 100 μm and a depth of 100 μm. The titanium alloy plate was used as two electrodes and placed in acetone / ethanol (v / v = 1:1) to remove surface contaminants. The titanium alloy plate after decontamination was subjected to chemical nickel plating at a rate of 3 dm per liter of plating solution. 2The composition of the plating solution is as follows: 3.0% NiSO4·6H2O, 3.4% NaH2PO2·H2O, 1.7% NaAC·3H2O, 3.0% C3H6O3, 0.01% Pb2+, and the rest is deionized water. The temperature is 90°C and the plating time is 1h to obtain a nickel-titanium alloy plate; the carbon nanotubes are acidified by using a HNO3 / H2SO4 (v / v=1:3) mixed solution at 80°C for 2h; the mixture is washed with deionized water until neutral, and then vacuum filtered with a microporous membrane with a pore size of 0.45μm, and then freeze-dried at -40°C for 2h to obtain carboxylic acid-functionalized carbon nanotubes; finally, The carbon nanotube suspension was prepared by dispersing carbon nanotubes in ethanol to prepare a 1 mg / mL suspension, and 0.15 times the mass of the suspension was added with Mg(NO3)2·6H2O to improve the conductivity of the suspension to prepare a carbon nanotube suspension; finally, the carbon nanotube layer on the surface of the nickel layer was obtained by electrophoretic deposition in the carbon nanotube suspension at a working distance of 15 mm between two electrodes and a working voltage of 50 V for 5 minutes; the deposited titanium alloy plate and the carbon fiber composite material were overlapped together, and then laser welded by laser welding. The laser welding parameters were 0.6 kW laser power, 0.8 m / min scanning speed, and 0.95 m spot diameter to obtain a titanium alloy and carbon fiber reinforced composite material.

[0035] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that step (1) is different. Step (1) is changed to: immerse a plain weave of a carbon fiber tow with T700 and warp and weft yarns of 24K in distilled water, with a solid-liquid ratio of carbon fiber to distilled water of 1:3, and subject to microwave radiation; the microwave radiation conditions are set to 2.45 GHz, 600 W, and a treatment time of 130 s; after the treatment, cool to room temperature, and then ultrasonicate at 50 kHz for 45 min; after the ultrasonication, take the solid and wash it with deionized water 3 times, and then dry it in a drying oven at 50°C for 6 h; finally, subject the dried carbon fiber to isopulse plasma treatment with a power of 120 W, a time of 35 s, and an ion of H2O, and after the treatment, a modified carbon fiber is obtained; the remaining steps are the same as Example 2.

[0036] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that step (1) is different, and step (1) is changed to: immerse the carbon fiber tow plain weave with T700 and warp and weft yarns of 24K in a 2% hydrogen peroxide concentration for modification, and the solid-liquid ratio of the carbon fiber tow plain weave to the hydrogen peroxide is 1:3; the above-mentioned mixed solution is sealed and placed in a vacuum drying oven, and reacted at 100°C for 10 minutes; after the reaction, it is cooled to room temperature, the mixed solution is filtered to obtain the solid, and the solid is washed with deionized water 3 times to remove the residue, so as to obtain oxidized carbon fiber; then the oxidized carbon fiber is immersed in distilled water, the solid-liquid ratio of the oxidized carbon fiber to distilled water is 1:3, and ultrasonic treatment is carried out at 50kHz for 45 minutes; after the ultrasonic treatment, the solid is washed with deionized water 3 times, and then dried in a drying oven at 50°C for 6 hours; finally, the dried carbon fiber is subjected to isopulse plasma treatment with a power of 120W, a time of 35s, and an ion body of H2O. After the treatment, modified carbon fiber is obtained; the remaining steps are the same as those in Example 2.

[0037] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that step (1) is different, and step (1) is changed to: immersing the carbon fiber tow plain weave with T700 and warp and weft yarns of 24K in a 2% hydrogen peroxide concentration for modification, and the solid-liquid ratio of the carbon fiber tow plain weave to the hydrogen peroxide is 1:3; the above-mentioned mixed solution is sealed and placed in a vacuum drying oven, and reacted at 100°C for 10 minutes; after the reaction is completed, it is cooled to room temperature, the mixed solution is filtered to obtain a solid, and the residue is washed three times with deionized water to obtain an oxidized carbon fiber; and the oxidized carbon fiber is then The oxidized carbon fiber is immersed in distilled water, the solid-liquid ratio of the oxidized carbon fiber and distilled water is 1:3, and microwave irradiation is performed; the microwave irradiation conditions are set to 2.45 GHz, 600 W, and the treatment time is 130 s; after the treatment, it is cooled to room temperature, the solid is washed with deionized water 3 times, and then dried in a drying oven at 50°C for 6 h; finally, the dried carbon fiber is subjected to isopulse plasma treatment with a power of 120 W, a time of 35 s, and a plasma of H2O. After the treatment, modified carbon fiber is obtained; the remaining steps are the same as in Example 2.

[0038] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that step (1) is different, and step (1) is changed to: immerse the carbon fiber tow plain weave with T700 and warp and weft yarns of 24K in a 2% hydrogen peroxide concentration for modification, and the solid-liquid ratio of the carbon fiber tow plain weave to the hydrogen peroxide is 1:3; the above-mentioned mixed solution is sealed and placed in a vacuum drying oven, and reacted at 100°C for 10 minutes; after the reaction, it is cooled to room temperature, the mixed solution is filtered to obtain the solid, and the solid is washed with deionized water 3 times to wash away the residue, so as to obtain oxidized carbon fiber; then the oxidized carbon fiber is immersed in distilled water, the solid-liquid ratio of the oxidized carbon fiber to distilled water is 1:3, and microwave irradiation is performed; the microwave irradiation conditions are set to 2.45GHz, 600W, and the treatment time is 130s; after the treatment, it is cooled to room temperature, and then ultrasonicated at 50kHz for 45min; after the ultrasonication, the solid is washed 3 times with deionized water, and then dried in a drying oven at 50°C for 6h to obtain modified carbon fiber after drying; the remaining steps are the same as Example 2.

[0039] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that step (3) is different, and step (3) is changed to: using a nanosecond pulse fiber laser with a wavelength of 1030nm, a beam diameter of 30μm, a laser power of 70w, and a scanning speed of 700mm / s to prepare rows of strip microtextures on the surface of the TC4 titanium alloy plate, each microtexture is 100μm apart, and the strip pattern is 100μm wide and 100μm deep; the titanium alloy plate is used as two electrodes and placed in acetone / ethanol (v / v=1:1) to remove surface pollutants; the carbon nanotubes are acid-treated, and the carbon nanotubes are acidified with a mixed solution of HNO3 / H2SO4 (v / v=1:3) at 80°C for 2h; the mixture is washed with deionized water until neutral, and then vacuum filtered with a microporous membrane with a pore size of 0.45μm, and then After freeze-drying at -40°C for 2 hours, carboxylic acid functionalized carbon nanotubes were obtained; finally, a 1 mg / mL suspension was prepared by dispersing the carbon nanotubes in ethanol, and 0.08 times the mass of the suspension was added with Mg(NO3)2·6H2O to improve the conductivity of the suspension and prepare a carbon nanotube suspension; finally, the carbon nanotube layer on the surface of the decontaminated titanium alloy plate was obtained by electrophoretic deposition in the carbon nanotube suspension at a working distance of 15 mm between two electrodes and a working voltage of 50 V for 5 minutes; the deposited titanium alloy plate and the carbon fiber composite material were overlapped together, and then laser welded by laser welding, the laser welding parameters were 0.6 kW laser power, 0.8 m / min scanning speed, and 0.95 m spot diameter to obtain a titanium alloy and carbon fiber reinforced composite material; the remaining steps were the same as Example 2.

[0040] Effect example

[0041] Table 1 below shows the performance analysis results of a TC4 titanium alloy and carbon fiber reinforced composite material using Examples 1 to 3 of the present invention and Comparative Examples 1 to 5.

[0042] Table 1

[0043] Connection strength / MPa Example 1 18.02 Example 2 18.02 Example 3 18.00 Comparative Example 1 15.33 Comparative Example 2 16.20 Comparative Example 3 16.38 Comparative Example 4 15.81 Comparative Example 5 14.62

[0044] From the comparison of the experimental data of wear resistance of the embodiment and the comparative example, it can be found that the present invention uses hydrogen peroxide to modify the surface of overly thick carbon fiber, and the hydroxyl radicals and oxygen radicals after decomposition of hydrogen peroxide react with the carbon fiber for oxidation, and perform stripping and etching to prepare carbon fiber with graphene oxide on the surface, and then further deepen the surface oxidation depth of the carbon fiber through microwave radiation, and at the same time, the loosely attached graphene oxide can be stripped; then, by controlling the conditions of ultrasonic treatment, the graphene oxide on the surface is partially stripped off, and after plasma beam treatment and impact, the graphite crystals with large crystal size and relatively dense arrangement in the carbon fiber cortex are further broken, and the grooves and pores on the surface of the carbon fiber are increased and expanded, so that the active groups and the concave-convex structure on the surface of the modified carbon fiber after subsequent resin filling and curing, the physical interlocking and chemical bonding complement each other to achieve higher bonding strength, thereby improving the strength of the carbon fiber composite material. Secondly, the present invention first chemically deposits a layer of nano nickel on the micro-textured surface of the titanium alloy, and then deposits acid-treated carbon nanotubes on the surface of the nano nickel through electrophoretic deposition technology; the carboxyl protons at the edges of the modified carbon nanotubes are replaced by nickel elements to form a dipole moment, thereby improving the wetting and spreading ability of the interface and reducing the residual stress after welding the titanium alloy and the carbon fiber composite material; the nano nickel reacts and combines with the titanium metal at a high temperature to form an alloy on the contact surface, thereby reducing the penetration and corrosion of the modified carbon nanotubes on the titanium alloy, improving the toughness between the composite material layers, and forming a multifunctional intercalated self-supporting structure; finally, the treated titanium alloy and the carbon fiber reinforced composite material are welded together through a laser to prepare a micro texture on the surface of the titanium alloy, increase the mechanical bite force between the titanium alloy and the carbon fiber composite material, and improve the connection strength.

[0045] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A laser welding method for TC4 titanium alloy and carbon fiber reinforced composite material, characterized in that: The method comprises the following preparation steps: (1) The carbon fiber tow with T700 and 24K warp and weft yarns is immersed in hydrogen peroxide for modification; the mixed solution is sealed and placed in a vacuum drying oven for reaction at 80-120°C for 10 minutes; after the reaction is completed, the mixed solution is cooled to room temperature, the solid is filtered and washed with deionized water for 3 times to remove the residue, and the oxidized carbon fiber is obtained; the oxidized carbon fiber is then immersed in distilled water for microwave irradiation; the microwave irradiation conditions are set to 2.45GHz, 600W, and the treatment time is 60-200s; after the treatment, it is cooled to room temperature and then ultrasonicated at 40-60kHz for 30-60min; after the ultrasonication, the solid is washed with deionized water 3 times, and then dried in a drying oven at 50°C for 6h; finally, the dried carbon fiber is subjected to plasma treatment at a power of 100-140W for 10-60s, and the plasma is H2O, and the modified carbon fiber is obtained after the treatment; (2) 3-4 parts of dimethylformamide, 2-4 parts of ethyl acetate, 4-5 parts of polyamide, and 0.1-0.5 parts of a surfactant are mixed and stirred at 60 rpm for 10 min to prepare a sizing solution; the sizing solution is evenly applied to the surface of the modified carbon fiber obtained, and then dried at a drying temperature of 120° C. for 1 min; after the first sizing is completed, the above operation is repeated for a second sizing until the volume ratio of the outer layer resin to the inner layer carbon fiber is 1:1-1.2, and then cured at 120° C. for 5 h. After the curing is completed, a carbon fiber composite material is obtained; (3) Using a 1030 nm nanosecond pulsed fiber laser with a beam diameter of 30 μm, a laser power of 70 W, and a scanning speed of 700 mm / s, a row of stripe microtextures were prepared on the surface of a TC4 titanium alloy plate. Each microtexture was spaced 100 μm apart, and the stripe pattern had a width of 100 μm and a depth of 100 μm. The titanium alloy plate was used as two electrodes and placed in acetone / ethanol (v / v = 1:1) to remove surface contaminants. The titanium alloy plate after decontamination was subjected to chemical nickel plating at a rate of 1-3 dm per liter of plating solution. 2 ratio, and the plating time is 1h to obtain a nickel-titanium alloy plate; finally, the carbon nanotube layer on the surface of the nickel layer is obtained by electrophoretic deposition in a carbon nanotube suspension at a working distance of 15mm between two electrodes and a working voltage of 50V for 5min; the deposited titanium alloy plate and the carbon fiber composite material are overlapped together, and then laser welded to obtain a titanium alloy and carbon fiber reinforced composite material.

2. The laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material according to claim 1, characterized in that: The concentration of hydrogen peroxide in step (1) is 1-3%.

3. The laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material according to claim 1, characterized in that: In the step (1), the solid-to-liquid ratio of the carbon fiber tow plain weave to the hydrogen peroxide is 1:

3.

4. The laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material according to claim 1, characterized in that: In the step (1), the solid-to-liquid ratio of the oxidized carbon fiber to distilled water is 1:

3.

5. The laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material according to claim 1, characterized in that: The plasma treatment in step (1) is performed by pulsed plasma treatment.

6. The laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material according to claim 1, characterized in that: The surfactant in step (2) is Tween 60.

7. The laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material according to claim 1, characterized in that: The sizing speed in step (2) is 1 m / min.

8. The laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material according to claim 1, characterized in that: The components of the plating solution in step (3) are: 2.5-3.0% NiSO4·6H2O, 3-3.4% NaH2PO2·H2O, 1.3-1.7% NaAC·3H2O, 2.6-3.0% C3H6O3, 0.01% Pb2+, and the rest is deionized water, and the temperature is 90°C.

9. The laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material according to claim 1, characterized in that: The method for preparing the carbon nanotube suspension in step (3) is as follows: acid-treating the carbon nanotubes by acidifying the carbon nanotubes with a HNO3 / H2SO4 (v / v=1:3) mixed solution at 80°C for 2h; washing the mixture with deionized water until it is neutral, vacuum filtering it with a microporous membrane with a pore size of 0.45μm, and then freeze-drying it at -40°C for 2h to obtain carboxylic acid-functionalized carbon nanotubes; finally, dispersing the carbon nanotubes in ethanol to prepare a 1mg / mL suspension, and adding Mg(NO3)2·6H2O in an amount of 0.01-0.15 times the mass of the suspension to improve the conductivity of the suspension.

10. The laser welding method of TC4 titanium alloy and carbon fiber reinforced composite material according to claim 1, characterized in that: The laser welding parameters in step (3) are 0.6 kW laser power, 0.8 m / min scanning speed, and 0.95 m spot diameter.