Bi-Sn-In-Ga-Zn five-element low-temperature brazing filler metal doped with aminated carbon quantum dots as well as preparation method and application of Bi-Sn-In-Ga-Zn five-element low-temperature brazing filler metal

Abstract

The invention discloses a Bi-Sn-In-Ga-Zn five-element low-temperature brazing filler metal doped with aminated carbon quantum dots and a preparation method and application of the Bi-Sn-In-Ga-Zn five-element low-temperature brazing filler metal, and belongs to the technical field of superconducting material low-temperature connection. Raw materials of the Bi-Sn-In-Ga-Zn five-element low-temperature brazing filler metal comprise Bi-Sn-In-Ga-Zn matrix powder and the aminated carbon quantum dots; the mass ratio of the aminated carbon quantum dots to the Bi-Sn-In-Ga-Zn matrix powder is 0.5 to (95 to 100). The preparation process comprises the following steps: ball-milling and drying brazing filler metal powder; the carbon quantum dots are hydrolyzed and aminated through a silane coupling agent KH550, and the aminated carbon quantum dots and brazing filler metal powder are subjected to composite ball milling and then dried. The brazing filler metal prepared through the method is suitable for low-temperature connection of Nb-Ti alloy and fused quartz glass, the interface superconducting performance is enhanced through the carbon quantum dots, and the problem that a substrate is damaged at the high temperature in traditional brazing is solved.

Description

Technical Field

[0001] This invention belongs to the field of low-temperature bonding technology of superconducting materials, and particularly relates to a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots, its preparation method and application. Background Technology

[0002] In cutting-edge fields such as particle detectors, superconducting magnets, and controlled nuclear fusion devices, the reliable low-temperature bonding of Nb-Ti superconducting alloys with fused silica glass is a core bottleneck restricting system performance. Such bonding needs to maintain superconducting stability at liquid helium temperatures; however, current technologies face two major challenges: 1. Existing brazing filler metals cause a double degradation in both connection strength and superconducting performance. Existing low-temperature brazing alloy systems (such as the Bi-In-Zn alloy in patent CN104018026A) meet the melting point requirement (178℃), but during brazing, Ti reacts with oxygen in the quartz to form a micron-sized brittle Ti-O phase, causing interfacial cracks to propagate along the brittle phase, resulting in low joint strength. This brittle phase also hinders electron transport, leading to a significant reduction in the critical current density.

[0003] Second: Carbon material reinforcement solutions are mired in functionalization and dispersion dilemmas. Patent CN114414333A uses mechanical ball mixing to embed graphene into solder, but the unfunctionalized carbon surface cannot form chemical bonds with SiO2. The aggregated graphene sheets cause local electric field distortion, leading to a surge in interfacial resistance. While CN120664535A activates the carbon nanotube surface through argon plasma bombardment, improving interfacial strength, its high processing cost per kilogram and reliance on ultra-high vacuum equipment limit its applicability.

[0004] Therefore, there is an urgent need to develop a low-temperature solder that can simultaneously achieve the following objectives: while ensuring the formation of a high-strength, durable joint in Nb-Ti alloy / fused silica under low-temperature conditions, it intrinsically improves the interfacial superconductivity. Summary of the Invention

[0005] To address the problems of low strength, poor interfacial superconductivity, uneven carbon material dispersion, and high functionalization costs in existing low-temperature brazed joints, this invention proposes a Bi-Sn-In-Ga-Zn pentagonal low-temperature brazing alloy doped with aminated carbon quantum dots, along with its preparation method and applications. Specifically, this invention introduces aminated carbon quantum dots to achieve chemical bonding between the brazing alloy and fused silica glass, suppressing the formation of brittle phases and significantly improving the joint's mechanical properties and interfacial electron transport capabilities.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots, the raw materials of which include Bi-Sn-In-Ga-Zn matrix powder and aminated carbon quantum dots; The mass ratio of the aminated carbon quantum dots to the Bi-Sn-In-Ga-Zn matrix powder is 0.5:95-100.

[0007] Optionally, the mass ratio of the aminated carbon quantum dots to the Bi-Sn-In-Ga-Zn matrix powder is 0.5:95.

[0008] Optionally, the Bi-Sn-In-Ga-Zn matrix powder, by mass percentage, comprises the following components: Bi 20%, Sn 30%, In 15%, Ga 15% and Zn 20%.

[0009] Furthermore, the preparation process of the Bi-Sn-In-Ga-Zn matrix powder is as follows: Bi, Sn, In, Ga, and Zn metal powders were weighed according to their mass percentages, immersed in anhydrous ethanol, and then ball-milled and dried to prepare the Bi-Sn-In-Ga-Zn matrix powder.

[0010] Furthermore, the conditions for the ball milling process are: ball milling temperature ≤ 30℃, ball-to-material ratio 12:1, rotation speed 300 rpm, ball milling for 1 hour followed by standing for 30 minutes, and repeating the cycle 8 times.

[0011] Optionally, the preparation process of the aminated carbon quantum dots is as follows: Carbon quantum dots were dispersed in anhydrous ethanol to obtain a carbon quantum dot ethanol solution. Then, silane coupling agent and deionized water were added to the solution for amination treatment. After centrifugation and vacuum freeze-drying, amination carbon quantum dot powder was obtained.

[0012] Furthermore, the mass ratio of the carbon quantum dot ethanol solution, silane coupling agent, and deionized water is 85-90:10:2.

[0013] Furthermore, the silane coupling agent is KH550.

[0014] Optionally, the amination treatment conditions are: hydrolysis at room temperature for 1 hour at a rotation speed of 300 rpm.

[0015] Optionally, the centrifugation conditions are: centrifugation at 8000 rpm for 15 min.

[0016] Optionally, the vacuum freeze-drying conditions are as follows: vacuum degree ≤ 5 Pa, pre-freezing at -50℃ for 2 hours, increasing to -10℃ at 5℃ / h and holding for 4 hours, and then increasing to 25℃ at 10℃ / h and holding for 2 hours.

[0017] A method for preparing a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots includes the following steps: The Bi-Sn-In-Ga-Zn pentagonal low-temperature solder was prepared by mixing an aminated carbon quantum dot ethanol solution with Bi-Sn-In-Ga-Zn matrix powder and then ball milling and vacuum drying.

[0018] Optionally, the ball milling conditions are: ball-to-material ratio 5:1, rotation speed 200 rpm, 1 hour of ball milling followed by 30 minutes of rest, for a total of 4 cycles.

[0019] Optionally, the vacuum drying conditions are: a vacuum degree ≤ 10. -3 Dry at 50℃ for 2 hours.

[0020] The application of the above-mentioned Bi-Sn-In-Ga-Zn pentagonal low-temperature solder in the low-temperature bonding of Nb-Ti alloy and fused silica glass.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects: This invention introduces amination carbon quantum dots, whose surface -NH2 functional groups react with the Si-OH groups on the surface of fused silica to form Si-N bonds, achieving chemical metallurgical bonding and significantly improving interfacial bonding strength. Furthermore, the amination carbon quantum dots act as nucleation centers, refining the brazed joint microstructure and inhibiting the formation and growth of the brittle Ti-O phase. The amination carbon quantum dots also possess excellent electron transport capabilities, forming conductive pathways and effectively enhancing interfacial superconductivity. Moreover, this invention employs a wet chemical method for amination of carbon quantum dots, resulting in a simple, low-cost process that is easy to scale up for production.

[0022] In summary, the solder prepared by the method of this invention has a low melting point (≤180℃), making it suitable for low-temperature bonding of heat-sensitive materials and avoiding degradation of the base material properties. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a process flow diagram for preparing the Bi-Sn-In-Ga-Zn pentagonal low-temperature solder with composite aminated carbon quantum dots of the present invention. Figure 2 The image shows the interface SEM morphology of the brazed joint obtained in Embodiment 1 of the present invention. Figure 3This is a comparison chart of the critical current densities of brazed joints obtained using Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0029] This invention discloses a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder containing aminated carbon quantum dots, comprising a Bi-Sn-In-Ga-Zn matrix alloy and aminated carbon quantum dots; By mass percentage, the Bi-Sn-In-Ga-Zn matrix alloy consists of the following components: Bi 20%, Sn 30%, In 15%, Ga 15%, Zn 20%; The mass ratio of the aminated carbon quantum dots to the Bi-Sn-In-Ga-Zn matrix powder is 0.5:95-100.

[0030] In some alternative embodiments, the aminated carbon quantum dots have a particle size of 3-8 nm and are rich in -NH2 functional groups on their surface, which can form stable Si-N covalent bonds with Si-OH on the surface of fused silica glass, effectively enhancing the interfacial bonding force.

[0031] In some alternative embodiments, the Bi-Sn-In-Ga-Zn matrix alloy has a melting point of 176°C, which meets the requirements of low-temperature brazing process and avoids thermal damage to the Nb-Ti superconducting alloy and fused silica glass.

[0032] like Figure 1 As shown, this invention also discloses a method for preparing a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder containing aminated carbon quantum dots, comprising the following steps: (1) Weigh Bi, Sn, In, Ga and Zn metal powders, mix them in proportion, and add anhydrous ethanol to immerse the powders; (2) Ball milling parameter control: ball-to-material ratio 12:1, rotation speed 300 rpm, ball milling for 1 hour and then standing for 30 minutes, repeating 8 cycles, vacuum drying for 3 hours, to obtain uniformly mixed Bi-Sn-In-Ga-Zn powder; (3) Preparation of aminated carbon quantum dots: (a) Disperse carbon quantum dots in anhydrous ethanol, then add silane coupling agent KH550 and deionized water, and hydrolyze at room temperature for 1 hour at 300 rpm. (b) Centrifugation purification of the hydrolysate: Centrifuge at 8000 rpm for 15 min, remove the precipitate, and retain the supernatant; (c) The supernatant was freeze-dried under vacuum: pre-frozen at -50℃ for 2h, raised to -10℃ at 5℃ / h and held for 4h, and then raised to 25℃ at 10℃ / h and held for 2h to obtain aminated carbon quantum dot powder. (d) The aminated carbon quantum dot powder was ultrasonically dispersed in anhydrous ethanol at 400W for 30 min to obtain a uniformly dispersed aminated carbon quantum dot ethanol solution. (4) Preparation of composite brazing filler metal: The aminated carbon quantum dot ethanol solution and the Bi-Sn-In-Ga-Zn powder obtained in step (2) are mixed at a mass ratio of 10:95, the ball-to-material ratio is 5:1, the rotation speed is 200 rpm, the ball milling is performed for 1 hour and then left to stand for 30 minutes. After a total of 4 cycles, the mixture is vacuum dried for 2 hours to obtain the composite brazing filler metal containing aminated carbon quantum dots.

[0033] In some alternative embodiments, the ball milling process in step (2) needs to be controlled at a temperature of ≤30°C to prevent local melting of low-melting-point metals (such as Ga and In) from causing powder agglomeration.

[0034] In some alternative embodiments, the centrifugation speed in step (3) is 8000 rpm to ensure effective removal of unreacted KH550 and byproducts.

[0035] In some optional embodiments, the vacuum degree of vacuum freeze drying in step (3) is ≤5Pa, and the vacuum degree change rate is kept ≤0.5Pa / h during the heating process to prevent the carbon quantum dot structure from being destroyed.

[0036] In some optional embodiments, the vacuum drying conditions in step (4) are: vacuum degree ≤ 10 -3 Pa, temperature 50℃, to ensure complete ethanol evaporation and stable amino groups.

[0037] In addition, the present invention also discloses the application of a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder containing aminated carbon quantum dots in the low-temperature bonding of Nb-Ti alloy and fused silica glass; The conditions for cryogenic joining are: in an argon atmosphere, the joining temperature is ≤200℃, and the holding time is 10-30 min. Under these conditions, the joint shear strength can reach ≥35MPa, and the critical interfacial current density can be increased by ≥30%.

[0038] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0039] All raw materials used in this invention were purchased from the market.

[0040] The technical solution of the present invention will be further illustrated by the following embodiments.

[0041] Example 1 A method for preparing a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder containing aminated carbon quantum dots includes the following steps: S1. Preparation of matrix powder: Weigh 20g Bi, 30g Sn, 15g In, 15g Ga, and 20g Zn metal powder, immerse them in anhydrous ethanol, place them in a planetary ball mill with a ball-to-powder ratio of 12:1 and a rotation speed of 300 rpm, ball mill for 1 hour, let stand for 30 minutes, repeat 8 cycles, control the temperature ≤30℃ during the process, and finally dry in a vacuum drying oven at 60℃ for 3 hours to obtain Bi-Sn-In-Ga-Zn matrix powder; S2, Preparation of aminated carbon quantum dots: (a) Disperse 1g of carbon quantum dots in 88g of anhydrous ethanol, add 10g of KH550 and 2g of deionized water, and stir at 300rpm at room temperature for 1h to hydrolyze. (b) Centrifuge the hydrolysate at 8000 rpm for 15 min, discard the precipitate, and keep the supernatant; (c) Place the supernatant in a freeze dryer, pre-freeze at -50℃ for 2h, raise the temperature to -10℃ at a program of 5℃ / h and hold for 4h, then raise the temperature to 25℃ at a program of 10℃ / h and hold for 2h, with a vacuum degree ≤5Pa, to obtain aminated carbon quantum dot powder. (d) Add 0.5g of aminated carbon quantum dot powder to 9.5g of anhydrous ethanol and disperse by ultrasonication at 400W for 30min to obtain an aminated carbon quantum dot ethanol solution. S3. Preparation of composite solder: The above-mentioned aminated carbon quantum dot ethanol solution was mixed with 95g of matrix powder and placed in a ball mill jar. The ball-to-powder ratio was 5:1, the rotation speed was 200rpm, and the mixture was ball-milled for 1 hour. After standing for 30 minutes, the cycle was repeated 4 times. Finally, the mixture was milled at 50℃ and a vacuum degree ≤10. -3 Drying under Pa conditions for 2 hours yielded a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder (N-CQD) containing aminated carbon quantum dots.

[0042] Comparative Example 1 The difference from Example 1 is that no carbon quantum dots are added during the preparation process. Other conditions and parameters are the same as in Example 1.

[0043] The specific preparation process is as follows: Mix 9.5g of anhydrous ethanol with 95g of matrix powder, place the mixture in a ball mill jar at a ball-to-powder ratio of 5:1, and mill at 200 rpm for 1 hour. Let the mixture stand for 30 minutes, repeating this cycle 4 times. Finally, mill the mixture at 50℃ and a vacuum degree ≤10. -3 Drying under Pa conditions for 2 hours yielded a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder that does not contain carbon quantum dots.

[0044] Comparative Example 2 The difference from Example 1 is that the carbon quantum dots were not modified by amination, while the other conditions and parameters are the same as in Example 1.

[0045] Effect verification The brazing powders prepared in Example 1, Comparative Example 1, and Comparative Example 2 were placed between an Nb-Ti alloy and fused silica glass, and heated to 180°C at 20°C / min under an argon atmosphere and held for 5 min to obtain brazed joints.

[0046] Testing showed that the shear strength of the joint using the brazing filler metal prepared in Comparative Example 1 was 38.5 MPa, the shear strength of the joint using the brazing filler metal prepared in Comparative Example 2 was 40.1 MPa, and the shear strength of the joint using the brazing filler metal prepared in Example 1 of this invention was 53.1 MPa. The interfacial critical current density of the joint using the brazing filler metal prepared in Example 1 was increased by 38% compared to Comparative Example 1 without added carbon quantum dots, and by 32% compared to Comparative Example 2 (e.g., ...). Figure 3 (As shown).

[0047] Figure 2 The images show the interface SEM morphology of the brazed joint obtained in Example 1 of this invention; (a) is the complete joint interface between the Nb-Ti alloy and fused silica; (b) is the contact area between the quartz glass and the brazing filler metal; (c) is the EDS line scan data of the quartz glass / brazing filler metal interface; (d) is the contact area between the niobium-titanium alloy and the brazing filler metal; (e) is the EDS line scan data of the niobium-titanium alloy / brazing filler metal interface. As can be seen from the images, the complete joint interface between the Nb-Ti alloy and fused silica is present. The middle layer is a Bi-Sn-In-Ga-Zn matrix brazing filler metal layer. The interface is clear, without obvious cracks or pores, indicating that the weld is dense and well-bonded.

[0048] Figure 3 This is a comparison of the critical current densities of brazed joints obtained using Examples 1, 1, and 2 of this invention. At 4.2 K, the critical current density (Jc) of Nb-Ti / fused silica glass joints prepared using the N-CQD-doped (N-CQD) solder and the untreated (Untreated) solder of this invention is shown as a function of the applied magnetic field (Hc). The results show that in the low magnetic field region, the Jc of the N-CQD group is significantly higher than that of the untreated group, with a maximum increase of over 32%. This demonstrates that the Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with N-CQD prepared in the examples of this invention effectively improves the critical current performance of the superconducting joint, verifying its excellent functional enhancement effect in low-temperature joining.

[0049] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots, characterized in that, The raw materials include Bi-Sn-In-Ga-Zn matrix powder and aminated carbon quantum dots; The mass ratio of the aminated carbon quantum dots to the Bi-Sn-In-Ga-Zn matrix powder is 0.5:95-100.

2. The Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots according to claim 1, characterized in that, The mass ratio of the aminated carbon quantum dots to the Bi-Sn-In-Ga-Zn matrix powder is 0.5:

95.

3. The Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots according to claim 1, characterized in that, The Bi-Sn-In-Ga-Zn matrix powder comprises, by mass percentage, the following components: Bi 20%, Sn 30%, In 15%, Ga 15% and Zn 20%.

4. The Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots according to claim 1, characterized in that, The preparation process of the aminated carbon quantum dots is as follows: Carbon quantum dots were dispersed in anhydrous ethanol to obtain a carbon quantum dot ethanol solution. Then, silane coupling agent and deionized water were added to the solution for amination treatment. After centrifugation and vacuum freeze-drying, amination carbon quantum dot powder was obtained.

5. The Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots according to claim 4, characterized in that, The mass ratio of the carbon quantum dot ethanol solution, silane coupling agent, and deionized water is 85-90:10:

2. The silane coupling agent is KH550.

6. The Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots according to claim 4, characterized in that, The conditions for the amination treatment are: hydrolysis at 300 rpm for 1 hour at room temperature.

7. The Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots according to claim 4, characterized in that, The centrifugation conditions are: centrifugation at 8000 rpm for 15 min; and / or, The conditions for vacuum freeze drying are as follows: vacuum degree ≤ 5 Pa, pre-freeze at -50℃ for 2 hours, raise the temperature to -10℃ at 5℃ / h and maintain for 4 hours, and then raise the temperature to 25℃ at 10℃ / h and maintain for 2 hours.

8. A method for preparing a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots as described in any one of claims 1-7, characterized in that, Includes the following steps: The Bi-Sn-In-Ga-Zn pentagonal low-temperature solder was prepared by mixing an aminated carbon quantum dot ethanol solution with Bi-Sn-In-Ga-Zn matrix powder and then ball milling and vacuum drying.

9. The method for preparing Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots according to claim 8, characterized in that, The ball milling conditions are: ball-to-material ratio 5:1, rotation speed 200 rpm, 30-minute rest period after each 1-hour ball milling cycle, for a total of 4 cycles; and / or, The conditions for vacuum drying are: a vacuum degree ≤ 10. -3 Dry at 50℃ for 2 hours.

10. The application of a Bi-Sn-In-Ga-Zn pentagonal low-temperature solder doped with aminated carbon quantum dots as described in any one of claims 1-7 in the welding of Nb-Ti alloy to quartz glass.

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