A connecting material, its preparation method, a bolt and applications

Abstract

The present application discloses a connection material, a preparation method thereof, a bolt and an application, relating to the field of alloy materials. The preparation method of the connection material comprises the following steps: placing a carbon material in a strong acid, the strong acid including one or two of nitric acid and sulfuric acid, filtering for the first time to prepare a first solid; mixing the first solid with an organic material, the organic material including poly Schiff base, heating to 70°C to 90°C, and filtering for the second time to prepare a second solid. By placing a titanium alloy in the modified carbon material, the modified carbon material can bond with some active sites on the surface of the titanium alloy or form physical adsorption to perform surface modification on the titanium alloy, form a uniform covering layer on the surface of the titanium alloy, play a certain magnetic shielding role, change the distribution and propagation of the magnetic field on the surface of the titanium alloy, reduce the penetration of the external magnetic field into the titanium alloy, and improve the electromagnetic performance and mechanical performance of the connection material.

Description

Technical Field

[0001] The present application relates to the field of alloy materials, and particularly to a connection material, a preparation method thereof, a bolt, and an application thereof. Background Art

[0002] In the power system, the stability and safety of circuit connections are crucial. At present, circuit connections mainly rely on bolts for fixation. By treating the contact surface well to ensure its cleanliness and flatness, and then using bolts for tightening.

[0003] Traditional bolts are made of carbon steel materials, which will generate eddy current heating. Especially in high-voltage and large-current environments, due to the degradation of electromagnetic properties (such as resistivity, magnetic permeability) and mechanical properties (mass loss), abnormal heating and loosening are likely to occur, resulting in the failure of the fastening system, and also leading to power waste and safety accidents of joint heating. Summary of the Invention

[0004] Based on this, in order to improve the electromagnetic properties and mechanical properties of the connection material, it is necessary to provide a connection material, a preparation method thereof, a bolt, and an application thereof.

[0005] The preparation method of a connection material provided by the present application includes the following steps:

[0006] Placing a carbon material in a strong acid, the strong acid including one or both of nitric acid and sulfuric acid, and performing a first filtration to prepare a first solid;

[0007] Mixing the first solid with an organic material, the organic material including poly Schiff base, heating to 70°C - 90°C, and performing a second filtration to prepare a second solid;

[0008] Placing a titanium alloy in a modification solution, the modification solution including the second solid.

[0009] In one embodiment, before placing the titanium alloy in the modification solution, the following steps are further included:

[0010] Using the titanium alloy as an anode and placing it in an electrolytic solution together with a cathode material for electrolytic treatment.

[0011] In one embodiment, the electrolytic treatment satisfies one or more of the following conditions:

[0012] (1) The concentration of the metal salt in the electrolytic solution is 0.1 mol / L - 0.5 mol / L;

[0013] (2) The current density in the electrolytic treatment is 240 mA / cm 2 -250 mA / cm 2 ;

[0014] (3) The voltage in the electrolysis treatment is 5V to 120V;

[0015] (4) Before the titanium alloy undergoes the electrolysis treatment, it further includes a step of being placed in a cleaning solution, where the cleaning solution includes one or both of hydrofluoric acid and nitric acid;

[0016] (5) The material of the cathode is selected from one or more of platinum metal, nickel metal, palladium metal, and graphite.

[0017] In one embodiment, before the carbon material is placed in the strong acid, the following steps are further included:

[0018] Heat-treat the carbon material, place it in a pretreatment solution with a pH value of 1 to 2, filter, and dry.

[0019] In one embodiment, preparing the first solid satisfies one or more of the following conditions:

[0020] (1) The ratio of the carbon material to the strong acid is (5 to 15) g : (10 to 30) mL;

[0021] (2) The strong acid includes sulfuric acid and nitric acid with a molar ratio of (1 to 5) : 1;

[0022] (3) The time for the carbon material to be placed in the strong acid is 10h to 12h;

[0023] (4) The temperature for the carbon material to be placed in the strong acid is 35°C to 45°C.

[0024] In one embodiment, preparing the second solid satisfies one or both of the following conditions:

[0025] (1) The mass ratio of the first solid to the organic material is (0.1 to 2) : (0.01 to 1);

[0026] (2) The organic material further includes an organic solvent, and the organic material includes 0.5 parts to 5 parts of the poly Schiff base and 10 parts to 20 parts of the organic solvent.

[0027] In one embodiment, one or both of the following conditions are satisfied:

[0028] (1) The time for the titanium alloy to be placed in the modification solution is 20 min to 30 min;

[0029] (2) The composition of the titanium alloy includes vanadium metal, titanium metal, and aluminum metal.

[0030] This application also provides a connecting material prepared by the preparation method as described above.

[0031] Furthermore, the present application provides a bolt, including the connection material as described above.

[0032] Still further, the present application also provides the application of the above-mentioned connection material or the bolt as described above in circuit connection.

[0033] In the present application, titanium alloy is placed in the modified carbon material for modification. After modification, the carbon material can bond with some active sites on the surface of the titanium alloy or form physical adsorption to modify the surface of the titanium alloy, and has good bonding strength. A uniform carbon material coating is formed on the surface of the titanium alloy. Charge transfer may occur at the interface between the carbon material and the titanium alloy, changing the magnetic field distribution and reducing the penetration of the external magnetic field into the titanium alloy, playing a certain magnetic shielding role and improving the electromagnetic performance and mechanical performance of the connection material. Detailed Embodiments

[0034] For ease of understanding the present application, the present application will be described more comprehensively below. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0036] The term "and / or" as used herein includes any one of two or more related listed items, as well as any and all combinations of the related listed items. The any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items. For example, "A and / or B" includes three parallel solutions: A, B, and "the combination of A and B".

[0037] In this article, unless otherwise stated, "one or more" means any one of the listed items or any combination of the listed items. Similarly, in other cases where "one or more" and other expressions indicating "one or more" are used, the same understanding is made unless otherwise stated.

[0038] In this document, terms such as "further", "even further", "especially", "for example", "such as", "example", "exemplification", etc. are used for descriptive purposes, indicating an association in the covered content between different technical solutions before and after, but should not be construed as a limitation on the previous technical solution, nor as a limitation on the scope of protection of this document. In this document, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0039] In this document, "optionally", "optional", "option" mean that it can be either present or absent, that is, it refers to any one of the two parallel options of "present" or "absent". If "optional" appears multiple times in a technical solution, unless otherwise specified and there are no contradictions or mutual restrictions, each "optional" is independent. In this application, descriptions such as "optionally contain", "optionally include" mean "contain or not contain". "Optional component X" means that component X is present or absent, or means containing or not containing this component X.

[0040] In this document, in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or quantity, nor can they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive listing and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0041] In this document, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, as well as an open-ended technical solution containing the listed features.

[0042] In this document, regarding a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values within this numerical interval is considered continuous, and it includes the two numerical endpoints of this numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within this numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When providing multiple numerical ranges to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in this document should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" allows for a broad inclusion of numerical interval types such as percentage intervals, ratio intervals, ratio value intervals, etc.

[0043] In this text, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, such as 20°C ± 5°C. In some embodiments of this text, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of this text, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0044] In this text, for a method process involving multiple steps, unless there are clear different descriptions in this text, the execution of these steps has no strict order limit, and they can be executed in other orders than the described one. Moreover, any step may include multiple sub-steps or multiple stages. These sub-steps or stages do not necessarily need to be completed at the same moment, but can be executed at different moments, and their execution order is not necessarily sequential, but can be executed alternately or simultaneously with other steps or a part of the sub-steps or stages of other steps.

[0045] The present application provides a method for preparing a connection material, which includes the following steps S10 to step S30:

[0046] Step S10: Place the carbon material in a strong acid, where the strong acid includes one or both of nitric acid and sulfuric acid, and perform the first filtration to prepare a first solid;

[0047] Step S20: Mix the first solid with an organic material, where the organic material includes poly Schiff base, heat to 70°C to 90°C, and perform the second filtration to prepare a second solid;

[0048] Step S30: Place the titanium alloy in a modified solution, where the modified solution includes the second solid.

[0049] In the present application, the titanium alloy is placed in the modified carbon material for modification. The modified carbon material can bond with some active sites on the surface of the titanium alloy or form physical adsorption to perform surface modification on the titanium alloy, and has good bonding strength. A uniform carbon material covering layer is formed on the surface of the titanium alloy. Charge transfer may occur at the interface between the carbon material and the titanium alloy, changing the magnetic field distribution and reducing the penetration of the external magnetic field into the titanium alloy, playing a certain magnetic shielding role and improving the electromagnetic performance and mechanical performance of the connection material.

[0050] It can be understood that the above carbon material can be but is not limited to carbon nanotubes.

[0051] In a specific example, before placing the carbon material in the strong acid, the following step S1 is further included:

[0052] Heat-treat the carbon material, place it in a pretreatment solution with a pH value of 1 to 2, filter, and dry.

[0053] Further, the temperature of the heat treatment is 450°C to 480°C, and the time of the heat treatment is 20 min to 30 min. Specifically, the temperature of the heat treatment can be, but is not limited to, 450°C, 455°C, 460°C, 465°C, 470°C, 475°C or 480°C.

[0054] The above pretreatment solution can be, but is not limited to, an aqueous hydrochloric acid solution with a mass fraction of 37%. Specifically, the carbon material is heat-treated and placed in the pretreatment solution of the aqueous hydrochloric acid solution with a mass fraction of 37%, and stirred and refluxed for 3 days to 4 days.

[0055] It can be understood that after filtration and before drying in the above step S1, it also includes washing the filtered solid with water. Specifically, the solid is repeatedly washed with distilled water until the pH value of the washing solution is neutral.

[0056] Further, the drying temperature is 70°C to 80°C, and the drying time is 10 h to 12 h. Specifically, the drying temperature can be, but is not limited to, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C. The drying time can be, but is not limited to, 10 h, 10.5 h, 11 h, 11.5 h or 12 h.

[0057] Specifically, the above step S1 is to purify the carbon nanotubes, which can remove some volatile impurities, dissolve and remove metal impurities, etc., so as to obtain pure carbon nanotubes and improve the stability and reliability of their performance.

[0058] In a specific example, the ratio of the carbon material to the strong acid is (5 - 15) g : (10 - 30) mL. Further, the strong acid includes sulfuric acid and nitric acid with a molar ratio of (1 - 5) : 1. Specifically, the above strong acid can be, but is not limited to, an aqueous sulfuric acid solution with a mass fraction of 98% and an aqueous nitric acid solution with a mass fraction of 70% with a molar ratio of (2 - 4) : 1.

[0059] In a specific example, the time for the carbon material to be placed in the strong acid is 10 h to 12 h. Specifically, the time for the carbon material to be placed in the strong acid can be, but is not limited to, 10 h, 10.5 h, 11 h, 11.5 h or 12 h.

[0060] In a specific example, the temperature for the carbon material to be placed in the strong acid is 35°C to 45°C. Specifically, the temperature for the carbon material to be placed in the strong acid can be, but is not limited to, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C or 45°C.

[0061] After the above carbon material is placed in strong acid, it further includes adding 200 mL to 250 mL of deionized water to dilute the strong acid, followed by the first filtration. Then, it is washed 2 to 4 times with deionized water and dried to prepare the first solid.

[0062] Furthermore, the drying temperature is 60°C to 70°C, and the drying time is 16 h to 20 h. Specifically, the drying temperature can be, but is not limited to, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, or 70°C. The drying time can be, but is not limited to, 16 h, 17 h, 18 h, 19 h, or 20 h.

[0063] It can be understood that introducing oxygen-containing functional groups such as carboxyl groups on the surface of the carbon material, which can be, but is not limited to, carbon nanotubes, provides more reactive sites for chemical reactions on the surface of the carbon material, improving the compatibility and bonding force between the carbon material and the titanium alloy matrix.

[0064] In a specific example, in the preparation of the second solid, the mass ratio of the first solid to the organic material is (0.1 to 2) : (0.01 to 1).

[0065] In a specific example, in the preparation of the second solid, the organic material further includes an organic solvent. The organic material includes 0.5 parts to 5 parts of poly Schiff base and 10 parts to 20 parts of the organic solvent.

[0066] Furthermore, the organic solvent can be, but is not limited to, one or both of thionyl chloride and N,N-dimethylformamide.

[0067] Specifically, the first solid is first mixed with the first organic solvent and stirred for the first time at 60°C to 70°C. Then, poly Schiff base and the second organic solvent are added, and it is stirred for the second time under a protective gas atmosphere at 70°C to 90°C. After separating the solid, it is washed and dried to prepare the second solid. It can be understood that N,N-dimethylformamide and ethanol are respectively used for washing here.

[0068] Even further, the time for the first stirring is 20 h to 24 h, and the time for the second stirring is 10 h to 12 h.

[0069] Specifically, the time for the first stirring can be, but is not limited to, 20 h, 21 h, 22 h, 23 h, or 24 h.

[0070] The time for the second stirring can be, but is not limited to, 10 h, 11 h, or 12 h.

[0071] In a specific example, the mass ratio of the first organic solvent to the second organic solvent is (0.06 g to 0.1 g) : (16 g to 18.5 g).

[0072] In a specific example, the temperature of the above drying is 55°C to 65°C, and the drying time is 20 h to 24 h.

[0073] Through further grafting treatment, poly Schiff base organic molecules are grafted onto the surface of the carbon material. After grafting, the surface of the carbon material can form more complex and stable interactions with the surface energy of the titanium alloy, such as chemical bonding, physical entanglement, etc., thereby enhancing the bonding force between the carbon nanotubes and the titanium alloy, making the carbon nanotubes adhere more firmly to the surface of the titanium alloy and not easily fall off during application, improving the stability and durability of the connecting material.

[0074] In a specific example, before the step S30 of placing the titanium alloy in the modification solution, the following pretreatment step S3 of the titanium alloy is further included:

[0075] Taking the titanium alloy as the anode and placing it in the electrolyte together with the cathode material for electrolytic treatment.

[0076] Furthermore, before the electrolytic treatment in the pretreatment step S3, it also includes: successively grinding, polishing, first cleaning, drying the surface of the titanium alloy, and second cleaning in the cleaning solution. It can be understood that the cleaning solution includes one or both of hydrofluoric acid and nitric acid, and the second cleaning time is 5 min to 10 min.

[0077] Even further, after the electrolytic treatment in the pretreatment step S3, it also includes: the step of third cleaning.

[0078] Specifically, the third cleaning is successively carried out with deionized water and absolute ethanol. It can be understood that the deionized water and absolute ethanol are respectively used for washing 3 to 5 times.

[0079] In a specific example, the concentration of the metal salt in the electrolyte is 0.1 mol / L to 0.5 mol / L. The concentration of the metal salt in the electrolyte can be, but is not limited to, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L.

[0080] In a specific example, the current density in the electrolytic treatment is 240 mA / cm 2 -250 mA / cm 2 . Specifically, the current density in the electrolytic treatment can be, but is not limited to, 240 mA / cm 2 、241 mA / cm 2 、mA / cm 2 、242 mA / cm 2 、243 mA / cm 2 、244 mA / cm 2 、245 mA / cm 2, 246 mA / cm 2 , 247 mA / cm 2 , 248 mA / cm 2 , 249 mA / cm 2 or 250 mA / cm 2 .

[0081] In a specific example, the voltage in the electrolysis treatment is 5V - 120V. Specifically, the voltage in the electrolysis treatment can be but is not limited to 5V, 10V, 15V, 20V, 25V, 30V, 35V, 40V, 45V, 50V, 55V, 60V, 65V, 70V, 75V, 80V, 85V, 90V, 95V, 100V, 105V, 110V, 115V or 120V.

[0082] In a specific example, the material of the cathode is selected from one or more of platinum metal, nickel metal, palladium metal and graphite. Preferably, the cathode is platinum metal.

[0083] In a specific example, the time for the titanium alloy to be placed in the modification solution is 20min - 30min. Specifically, the time for the titanium alloy to be placed in the modification solution can be but is not limited to 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min or 30min.

[0084] In a specific example, the composition of the titanium alloy includes vanadium metal, titanium metal and aluminum metal.

[0085] By pretreating the titanium alloy as described above, its surface roughness is reduced to obtain a smooth and flat surface, which can effectively reduce surface defects, and can also remove the oxide scale, oil and other impurities on the surface of the titanium alloy. At the same time, a more stable oxide film is formed on the surface to enhance the corrosion resistance; by treatment in the electrolyte solution, the surface chemical composition and structure can be further changed to improve its corrosion resistance in various environments, and at the same time it has good electromagnetic properties and mechanical properties.

[0086] This application also provides a connecting material prepared according to the above preparation method.

[0087] Furthermore, this application provides a bolt including the connecting material as described above.

[0088] Even further, this application also provides the use of the connecting material as described above or the bolt as described above in circuit connection.

[0089] The present application will be further described in detail below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. For the experimental methods without specific conditions in the following embodiments, the guidance given in the present application shall be preferentially referred to, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturers, or by referring to the experimental methods known in the art.

[0090] In the following specific embodiments, regarding the measurement parameters of the raw material components, if there is no special instruction, there may be slight deviations within the weighing accuracy range. Regarding the temperature and time parameters, acceptable deviations caused by the instrument test accuracy or operation accuracy are allowed. "Normal temperature" refers to 25°C; "normal pressure" refers to 100 KPa or 101 KPa.

[0091] The titanium alloy used in the following examples and comparative examples is TC4 titanium alloy. Specifically, in the TC4 titanium alloy, the mass percentage of metallic titanium (Ti) is about 90%, the mass percentage of metallic aluminum (Al) is about 6%, the mass percentage of metallic vanadium (V) is about 4%, and a small amount of other elements such as iron, oxygen, carbon, etc.

[0092] The preparation method of poly Schiff base used in the following examples and comparative examples is as follows: Add dimethyl sulfoxide to equimolar 4,4'-diamino-3,3'-dichlorodiphenyl sulfone and terephthalaldehyde respectively, stir until completely dissolved and then mix, and slowly heat up to 80°C under the protection of xenon gas. After reacting for 4 h, cool, then pour into water for precipitation, filter, and then repeatedly dissolve with dimethyl sulfoxide and precipitate with water. Finally, place it in a vacuum drying oven at 60°C and dry for 48 h to obtain poly Schiff base.

[0093] Example 1

[0094] (1) Pretreat the titanium alloy: successively grind, polish, clean, and air-dry the surface of the titanium alloy; then put it into an acidic solution and perform acid treatment for 5 min; then put it into an electrolyte solution, the initial current density is 240 mA / cm 2 , the voltage is gradually increased from 5 V to 100 V, and the TC4 titanium alloy is used as the anode and the platinum sheet is used as the cathode; after electrolysis is completed, wash 3 times successively with deionized water and absolute ethanol, and then air-dry naturally;

[0095] Among them, the acidic solution is made by mixing 10 mL of hydrofluoric acid with a mass fraction of 35%, 10 mL of nitric acid with a mass fraction of 65%, and 80 mL of deionized water; the electrolyte solution is prepared from 0.3 mol / L sodium chloride, glycerol, absolute ethanol, and deionized water, and its volume ratio is: 0.3 mol / L sodium chloride: glycerol: absolute ethanol: deionized water = 3∶5∶4∶1;

[0096] (2) Purify the carbon nanotubes: Put the carbon nanotubes into a muffle furnace at 450 °C. After heat treatment for 20 min, stir and reflux with 37% hydrochloric acid by mass for 3 days, then filter, and repeatedly wash with distilled water until its pH is neutral. Finally, place it in a vacuum drying oven at 70 °C and dry for 10 h;

[0097] (3) Oxidize / carboxylate the purified carbon nanotubes: Pour 10 g of the purified carbon nanotubes into a mixed acid solution of 20 mL of 98% sulfuric acid solution and 65% nitric acid solution with a volume ratio of 3:1, and heat the water bath to 35 °C. At the same time, perform ultrasonic treatment for 10 h, then add 200 mL of deionized water for dilution and filtration, and wash 2 times with deionized water. Finally, place it in a drying oven at 60 °C and dry for 16 h;

[0098] (4) Modify the carbon nanotubes after oxidation / carboxylation treatment: Add 0.06 g of thionyl chloride to 0.5 g of the carbon nanotubes after oxidation / carboxylation treatment, and heat to 60 °C. After stirring for 20 h, cool, then perform rotary evaporation. Then add 1.5 g of poly Schiff base and 16 g of N,N-dimethylformamide, and under the protection of an argon atmosphere, heat to 70 °C at a heating rate of 2 °C / min and react for 10 h. After cooling, centrifuge and pour off the upper layer solution. The precipitate is washed 3 times with N,N-dimethylformamide and ethanol in sequence. Finally, place it in a vacuum drying oven at 55 °C and dry for 20 h;

[0099] (5) Add 20 mL of dimethyl sulfoxide solution to 5 g of the modified carbon nanotubes, then immerse the pretreated titanium alloy in it, make the solution cover the titanium alloy, and perform ultrasonic treatment for 20 min to obtain the joint material.

[0100] Example 2

[0101] (1) Pretreat the titanium alloy: Grind, polish, clean, and air-dry the surface of the titanium alloy in sequence; then put it into an acidic solution for acid treatment for 8 min; then put it into an electrolyte solution with an initial current density of 245 mA / cm 2 , the voltage gradually rises from 5 V to 100 V, and use TC4 titanium alloy as the anode and a platinum sheet as the cathode; after electrolysis is completed, wash 4 times with deionized water and absolute ethanol in sequence, and then air-dry naturally;

[0102] Among them, the acidic solution is made by mixing 11 mL of hydrofluoric acid with a mass fraction of 35%, 12 mL of nitric acid with a mass fraction of 65%, and 85 mL of deionized water; the electrolyte solution is prepared from 0.3 mol / L sodium chloride, glycerol, absolute ethanol, and deionized water, and its volume ratio is: 0.3 mol / L sodium chloride:glycerol:absolute ethanol:deionized water = 3∶5∶4∶1;

[0103] (2) Purify the carbon nanotubes: Put the carbon nanotubes into a muffle furnace at 460 °C. After heat treatment for 25 min, stir and reflux with 37% hydrochloric acid by mass fraction for 4 days, then filter, and repeatedly wash with distilled water until the pH is neutral. Finally, place it in a vacuum drying oven at 75 °C and dry for 11 h;

[0104] (3) Oxidize / carboxylate the purified carbon nanotubes: Pour 12 g of the purified carbon nanotubes into a mixed acid solution of 24 mL of 98% sulfuric acid solution and 65% nitric acid solution with a volume ratio of 3:1, and heat it in a water bath to 40 °C. At the same time, perform ultrasonic treatment for 11 h, then add 230 mL of deionized water for dilution and filtration, and wash with deionized water 3 times. Finally, place it in a drying oven at 65 °C and dry for 18 h;

[0105] (4) Graft the carbon nanotubes after oxidation / carboxylation treatment: Add 0.08 g of thionyl chloride to 0.6 g of the carbon nanotubes after oxidation / carboxylation treatment, and heat to 65 °C. Stir for 22 h and then cool, and then perform rotary evaporation. Then add 2.2 g of poly Schiff base and 17 g of N, N-dimethylformamide, and heat to 75 °C at a heating rate of 3 °C / min under the protection of an argon atmosphere and react for 11 h. After cooling, centrifuge and pour off the upper solution, and wash the precipitate with N, N-dimethylformamide and ethanol 4 times each. Finally, place it in a vacuum drying oven at 60 °C and dry for 22 h;

[0106] (5) Add 28 mL of dimethyl sulfoxide solution to 5 g of the carbon nanotubes after grafting treatment, and then immerse the pretreated titanium alloy in it, making the solution cover the titanium alloy, and perform ultrasonic treatment for 25 min to obtain the connecting material.

[0107] Example 3

[0108] (1) Pretreat the titanium alloy: Grind, polish, clean, and air-dry the surface of the titanium alloy in sequence; then put it into an acidic solution and perform acid treatment for 10 min; then put it into an electrolyte solution with an initial current density of 250 mA / cm 2 , and the voltage gradually rises from 5 V to 100 V, using TC4 titanium alloy as the anode and a platinum sheet as the cathode; after electrolysis is completed, wash with deionized water and absolute ethanol 5 times in sequence, and then air-dry naturally;

[0109] Among them, the acidic solution is made by mixing 12 mL of hydrofluoric acid with a mass fraction of 35%, 15 mL of nitric acid with a mass fraction of 65%, and 90 mL of deionized water; the electrolyte solution is prepared from 0.3 mol / L sodium chloride, glycerol, absolute ethanol, and deionized water, and its volume ratio is: 0.3 mol / L sodium chloride: glycerol: absolute ethanol: deionized water = 3∶5∶4∶1;

[0110] (2) Purify the carbon nanotubes: Put the carbon nanotubes into a muffle furnace at 480 °C. After heat treatment for 30 min, stir and reflux with 37% hydrochloric acid by mass fraction for 4 days, then filter, and repeatedly wash with distilled water until its pH is neutral. Finally, place it in a vacuum drying oven at 80 °C and dry for 12 h;

[0111] (3) Oxidize / carboxylate the purified carbon nanotubes: Pour 15 g of the purified carbon nanotubes into a mixed acid solution of 28 mL of 98% sulfuric acid solution and 65% nitric acid solution with a volume ratio of 3:1, and heat the water bath to 45 °C. At the same time, perform ultrasonic treatment for 12 h, then add 250 mL of deionized water for dilution and filtration, and then wash with deionized water 4 times. Finally, place it in a drying oven at 70 °C and dry for 20 h;

[0112] (4) Graft the carbon nanotubes after oxidation / carboxylation treatment: Add 0.1 g of thionyl chloride to 0.8 g of the carbon nanotubes after oxidation / carboxylation treatment, and heat to 70 °C. Stir for 24 h and then cool, then perform rotary evaporation. Then add 3 g of poly Schiff base and 18.5 g of N, N-dimethylformamide, and under the protection of an argon atmosphere, heat to 80 °C at a heating rate of 4 °C / min and react for 12 h. After cooling, centrifuge and pour off the upper layer solution. The precipitate is washed 5 times with N, N-dimethylformamide and ethanol in turn. Finally, place it in a vacuum drying oven at 65 °C and dry for 24 h;

[0113] (5) Add 30 mL of dimethyl sulfoxide solution to 5 g of the grafted carbon nanotubes, and then immerse the pretreated titanium alloy in it, so that the solution covers the titanium alloy, and perform ultrasonic treatment for 30 min to obtain the connecting material.

[0114] Example 4

[0115] Compared with Example 1, the difference is that the surface of the titanium alloy is not pretreated; the rest remains unchanged.

[0116] Comparative Example 1

[0117] Compared with Example 1, the difference is that only the carbon nanotubes are purified; the rest remains unchanged.

[0118] Comparative Example 2

[0119] Compared with Example 1, the difference is that only the titanium alloy is replaced with a carbon steel material, including about 90% iron (Fe) by mass percentage, about 7% carbon (C) by mass percentage, and a small amount of elements such as silicon (Si), manganese (Mn), sulfur (S), phosphorus (P), etc.; the rest remains unchanged.

[0120] Magnetic susceptibility measurement: Measured using a vibrating sample magnetometer; the results are shown in Table 1.

[0121] Corrosion resistance test: The specimen was placed in a salt spray test chamber for testing, and its mass loss rate was calculated; the results are shown in Table 1.

[0122] Table 1

[0123]

[0124] As can be seen from Table 1, the absolute values of the magnetic susceptibilities of Examples 1-4 are all greater than those of Comparative Examples 1-2. In particular, the absolute values of the magnetic susceptibilities of Examples 1-3 are significantly greater than those of Comparative Examples 1-2, indicating that the magnetic shielding performance of the connecting materials in Examples 1-3 is significantly improved compared to Comparative Examples 1-2. At the same time, the magnetic shielding performance of the connecting materials in Examples 1-3 is also improved compared to the connecting materials in Example 4.

[0125] As can be seen from Table 1, the mass loss rates of Examples 1-4 are less than those of Comparative Examples 1-2. In particular, the mass loss rates of Examples 1-3 are significantly less than those of Comparative Examples 1-2, indicating that the corrosion resistance of the connecting materials in Examples 1-3 is significantly improved compared to Comparative Examples 1-2. At the same time, the corrosion resistance of the connecting materials in Examples 1-3 is also improved compared to the connecting materials in Example 4.

[0126] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0127] The above embodiments only express several implementation manners of the present application, which are convenient for understanding the technical solutions of the present application specifically and in detail, but should not be construed as limiting the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can be made, and these all belong to the protection scope of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present application are all within the protection scope of the appended claims of the present application. Therefore, the protection scope of the patent of the present application should be subject to the content of the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. A method for preparing a connecting material, characterized in that, It includes the following steps: Place the carbon material in a strong acid, where the strong acid includes one or both of nitric acid and sulfuric acid, and conduct the first filtration to prepare a first solid; Mix the first solid with an organic material, where the organic material includes poly Schiff base, heat to 70°C to 90°C, and conduct the second filtration to prepare a second solid; Place the titanium alloy in a modification solution, where the modification solution includes the second solid; Before placing the carbon material in the strong acid, the following steps are also included: Heat-treat the carbon material, place it in a pretreatment solution with a pH value of 1 to 2, filter, and dry; Preparing the first solid meets one or more of the following conditions: (1) The ratio of the carbon material to the strong acid is (5 to 15) g : (10 to 30) mL; (2) The strong acid includes sulfuric acid and nitric acid with a molar ratio of (1 to 5) : 1; (3) The time for the carbon material to be placed in the strong acid is 10 h to 12 h; (4) The temperature for the carbon material to be placed in the strong acid is 35°C to 45°C.

2. The preparation method according to claim 1, characterized in that, Before placing the titanium alloy in the modification solution, the following steps are also included: Use the titanium alloy as the anode and place it in an electrolytic solution together with a cathode material for electrolytic treatment.

3. The preparation method according to claim 2, characterized in that, The electrolytic treatment meets one or more of the following conditions: (1) The concentration of the metal salt in the electrolytic solution is 0.1 mol / L to 0.5 mol / L; (2) The current density in the electrolytic treatment is 240 mA / cm 2 - 250 mA / cm 2 ; (3) The voltage in the electrolytic treatment is 5 V to 120 V; (4) Before the titanium alloy undergoes the electrolytic treatment, it also includes the step of being placed in a cleaning solution, where the cleaning solution includes one or both of hydrofluoric acid and nitric acid; (5) The cathode material is selected from one or more of metallic platinum, metallic nickel, metallic palladium, and graphite.

4. The preparation method according to claim 1, characterized in that, Preparing the second solid meets one or two of the following conditions: (1) The mass ratio of the first solid to the organic material is (0.1 to 2) : (0.01 to 1); (2) The organic material also includes an organic solvent, and the organic material includes 0.5 parts to 5 parts of the poly Schiff base and 10 parts to 20 parts of the organic solvent.

5. The preparation method according to any one of claims 1 to 4, characterized in that, Meets one or two of the following conditions: (1) The time for the titanium alloy to be placed in the modification solution is 20 min to 30 min; (2) The composition of the titanium alloy includes metallic vanadium, metallic titanium, and metallic aluminum.

6. A connecting material, characterized in that, Prepared according to the preparation method described in any one of claims 1 to 5.

7. A bolt, characterized in that, It includes the connecting material described in claim 6.

8. Application of the connecting material described in claim 6 or the bolt described in claim 7 in circuit connection.

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