Preparation and use of flux for low temperature braze of nbti superconducting wire

Abstract

The application discloses a preparation and use method of a NbTi superconducting wire low-temperature inlay welding flux, and relates to the technical field of superconducting wires, and comprises the following steps: heating deionized water to 50-60 DEG C; respectively water-bath heating short-chain alkyl glycoside and polyethylene glycol in the water at 50-60 DEG C for 30-60 seconds; stirring the obtained hot deionized water under the condition of 100-150 r / min, and adding the obtained short-chain alkyl glycoside and polyethylene glycol; and adding xanthan gum and sodium benzoate into the obtained solution in sequence to obtain the flux. The application uses short-chain alkyl glycoside as the main component of the flux; the addition of a thickening agent realizes the physical covering of the copper material surface and prevents the secondary oxidation of the copper material, so that the completely environment-friendly flux meeting the enterprise sewage discharge standard is suitable for the low-temperature inlay welding WIC conventional product with the largest base number, and the obtained WIC product has very low surface residue.

Description

Technical Field

[0001] This invention relates to the field of superconducting wire technology, and in particular to a method for preparing and using a low-temperature embedding welding flux for NbTi superconducting wires. Background Technology

[0002] NbTi superconducting wires used in superconducting magnetic resonance imaging (MRI) are nested structures consisting of an outer copper channel wire and a core of NbTi / Cu superconducting round wire, also known as wire-in-channel (WIC) wires. Due to their advantages such as a high copper ratio and low copper processing rate, their manufacturing cost is low, and the magnets produced are stable and safe. Therefore, they have become the dominant material for manufacturing superconducting magnets, a key component of MRI systems. WIC wires are typically produced using a dip-soldering method. The copper channel wire and the round wire are first passed through flux and high-temperature liquid solder respectively, and then joined together at a mold. After cooling, the resulting wire becomes the WIC wire.

[0003] There are many types of fluxes suitable for WIC inlay soldering, with inorganic fluxes and resin-based fluxes being the most widely used traditional fluxes. Inorganic fluxes typically contain lead and halogens, which release a large amount of pollutants during the soldering process, posing a threat to the environment and the health of operators. Resin-based fluxes are also unsuitable for WIC wire inlay soldering due to their flammability, severe carbonization problems leading to a high number of product defects, and other factors.

[0004] Against the backdrop of increasing global environmental awareness and the rapid development of the electronics manufacturing industry, completely environmentally friendly fluxes are gradually replacing traditional lead- and halogen-containing fluxes, becoming the preferred material in the welding field. However, the environmentally friendly fluxes currently available in the industry only achieve this through halogen-free formulation design, using sodium petroleum sulfonate, rosin alcohol ethers, alkyl glycosides, etc., to replace halogens as surfactants, and organic acids, synthetic resins, and mixed alcohol solvents to replace lead-based materials, effectively reducing pollutants. While flux is still used in welding, direct discharge of wastewater cannot meet the conditions of a pH of 6-9 and rapid microbial degradation found in industrial wastewater, thus failing to achieve true complete environmental protection. Summary of the Invention

[0005] This invention provides a method for preparing and using a low-temperature embedded soldering flux for NbTi superconducting wires. This addresses the problem that current environmentally friendly fluxes in the flux industry only achieve this through halogen-free formulations, using sodium petroleum sulfonate, rosin alcohol ethers, and alkyl glycosides as surfactants to replace halogens, and organic acids, synthetic resins, and mixed alcohol solvents to replace lead-based materials, effectively reducing pollutants. While flux is still used in soldering, direct discharge of wastewater fails to meet the requirements of a pH of 6-9 and rapid microbial degradation found in industrial wastewater, thus not achieving truly complete environmental protection.

[0006] On one hand, embodiments of the present invention provide a method for preparing a low-temperature embedded welding flux for NbTi superconducting wires, comprising:

[0007] Step 1: Heat the deionized water to 50-60 degrees Celsius;

[0008] Step 2: Heat the short-chain alkyl glycoside and polyethylene glycol separately in a water bath at 50-60 degrees Celsius for 30-60 seconds.

[0009] Step 3: Stir the preheated deionized water obtained in Step 1 at 100~150 r / min, and simultaneously add the short-chain alkyl glycoside and polyethylene glycol obtained in Step 2.

[0010] Step 4: Add xanthan gum and sodium benzoate sequentially to the solution obtained in Step 3 to prepare flux.

[0011] In one possible implementation, the proportions of deionized water, short-chain alkyl glycosides, xanthan gum, polyethylene glycol, and sodium benzoate in the flux are as follows: deionized water 98%–99%, short-chain alkyl glycosides 0.4%–0.8%, xanthan gum 0.4%–0.8%, polyethylene glycol 0.1%–0.2%, and sodium benzoate 0.1%–0.2%, with the short-chain alkyl glycosides having a chain length of C6–C14.

[0012] In one possible implementation, the preheated deionized water obtained in step one is stirred at 100-150 r / min, while the short-chain alkyl glycoside and polyethylene glycol obtained in step two are added, comprising:

[0013] The short-chain alkyl glycoside and polyethylene glycol obtained by heating in step two are added sequentially to the preheated deionized water. The single preparation volume of the solution formed by adding the short-chain alkyl glycoside and polyethylene glycol to the deionized water is less than 50L. The single preparation after adding the short-chain alkyl glycoside and polyethylene glycol is stirred for 3-5 minutes. The stirring time is extended as the single preparation volume increases.

[0014] In one possible implementation, the short-chain alkyl glycoside is one of a single-chain long-short-chain alkyl glycoside or a mixed-chain long-short-chain alkyl glycoside.

[0015] In one possible implementation, the short-chain alkyl glycoside is replaced with rhamnose ester, and the xanthan gum is replaced with one or more of sodium alginate, acrylamide, and modified starch.

[0016] On the other hand, embodiments of the present invention also provide a method for using a low-temperature inlay welding flux for NbTi superconducting wires. This method utilizes the NbTi superconducting wire low-temperature inlay welding flux prepared according to any one of the above-mentioned methods, and includes:

[0017] The processed parts are selected according to the WIC wire inlay welding process, and the processed parts include NbTi / Cu round wire and copper groove wire;

[0018] The low-temperature embedded welding flux for the NbTi superconducting wire is added to the flux bath;

[0019] The NbTi / Cu round wire and copper groove wire are pressed into the deoxidation tank and the flux tank in sequence. The low-temperature inlay welding flux of the NbTi superconducting wire is submerged in the NbTi / Cu round wire and the copper groove wire in the flux tank.

[0020] The NbTi / Cu round wire and copper channel wire, coated with the NbTi superconducting low-temperature inlay welding flux, are sequentially pressed into a soldering device, a cooling water tank, a traction machine, an eddy current flaw detector, and a take-up machine. The soldering device welds the NbTi / Cu round wire and copper channel wire to obtain NbTi superconducting wire. The eddy current flaw detector detects the inlay welding effect of the NbTi superconducting wire.

[0021] The preparation and application method of the low-temperature embedded welding flux for NbTi superconducting wires in this invention have the following advantages:

[0022] Short-chain alkyl glycosides are used as the main components of the flux; thickeners are added to physically cover the copper surface to prevent secondary oxidation of the copper; other materials that are easily degradable by microorganisms are added as other functional components of the flux. It is a completely environmentally friendly flux that can be dissolved in deionized water to obtain pH and rapid microbial degradation conditions that meet the wastewater discharge standards of enterprises. It is suitable for the largest number of low-temperature inlay soldering WIC conventional products, and the obtained WIC products have extremely low surface residue. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A flowchart illustrating a method for preparing a low-temperature embedded welding flux for NbTi superconducting wires, as provided in this application embodiment;

[0025] Figure 2A flowchart illustrating a method for using a low-temperature embellishment welding flux for NbTi superconducting wires, provided in this application embodiment;

[0026] Figure 3 A cross-sectional view of an NbTi superconducting circular wire provided for an embodiment of this application of a method of using a low-temperature embedded welding flux for NbTi superconducting wires;

[0027] Figure 4 A cross-sectional view of a copper channel wire for a method of using a low-temperature embedded welding flux for NbTi superconducting wires, provided in an embodiment of this application;

[0028] Figure 5 The image shows the solder filling effect on the surface of the WIC wire, which is a method for using a low-temperature inlay welding flux for NbTi superconducting wires according to an embodiment of this application. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Figure 1 A flowchart illustrating a method for preparing a low-temperature embedded soldering flux for NbTi superconducting wires, provided in an embodiment of this application; an embodiment of this invention provides a method for preparing a low-temperature embedded soldering flux for NbTi superconducting wires, comprising:

[0031] Step 1: Heat the deionized water to 50-60 degrees Celsius;

[0032] Step 2: Heat the short-chain alkyl glycoside and polyethylene glycol separately in a water bath at 50-60 degrees Celsius for 30-60 seconds.

[0033] Step 3: Stir the preheated deionized water obtained in Step 1 at 100~150 r / min, and simultaneously add the short-chain alkyl glycoside and polyethylene glycol obtained in Step 2.

[0034] Step 4: Add xanthan gum and sodium benzoate sequentially to the solution obtained in Step 3 to prepare flux.

[0035] The proportions of deionized water, short-chain alkyl glycosides, xanthan gum, polyethylene glycol, and sodium benzoate in the flux are as follows: deionized water 98%-99%, short-chain alkyl glycosides 0.4%-0.8%, xanthan gum 0.4%-0.8%, polyethylene glycol 0.1%-0.2%, and sodium benzoate 0.1%-0.2%. The short-chain alkyl glycosides have a chain length of C6-C14.

[0036] The preheated deionized water obtained in step one is stirred at 100-150 r / min, while the short-chain alkyl glycoside and polyethylene glycol obtained in step two are added.

[0037] The short-chain alkyl glycoside and polyethylene glycol obtained by heating in step two are added sequentially to the preheated deionized water. The single preparation volume of the solution formed by adding the short-chain alkyl glycoside and polyethylene glycol to the deionized water is less than 50L. The single preparation after adding the short-chain alkyl glycoside and polyethylene glycol is stirred for 3-5 minutes. The stirring time is extended as the single preparation volume increases.

[0038] The short-chain alkyl glycoside is one of a single-chain long-short-chain alkyl glycoside or a mixed-chain long-short-chain alkyl glycoside.

[0039] The short-chain alkyl glycoside is replaced with rhamnose ester, and the xanthan gum is replaced with one or more of sodium alginate, acrylamide, and modified starch.

[0040] For example, such as Figure 1 As shown, the raw materials were selected and weighed according to the preparation process of the completely environmentally friendly flux for low-temperature embedding welding of NbTi superconducting wires. The raw materials include deionized water (specific gravity 98%~99%), short-chain alkyl glycosides (chain length C6~C14, specific gravity 0.4%~0.8%), xanthan gum (specific gravity 0.4%~0.8%), polyethylene glycol PEG-400 (stabilizer, specific gravity 0.1%~0.2%), and sodium benzoate (preservative, specific gravity 0.1%~0.2%).

[0041] Step 1: Heat the deionized water to 50~60℃ and start preparing the flux.

[0042] Step 2: Preheat the short-chain alkyl glycoside and PEG-400 in hot water at 50~60℃ for 30~60s respectively.

[0043] Step 3: Stir the 50-60℃ hot water obtained in Step 1 at 100-150r / min, and slowly add the preheated short-chain alkyl glycoside and PEG-400 obtained in S3 to the hot water in sequence. The single preparation volume is less than 50L, and stir for 3-5min respectively. As the single preparation volume increases, the stirring time should be extended accordingly.

[0044] Step 4: Slowly add xanthan gum and sodium benzoate to the solution obtained in Step 3, and stir for 3-5 minutes respectively to obtain a completely environmentally friendly flux.

[0045] The flux obtained by the above method uses short-chain alkyl glycosides as the main component and adds thickeners to physically cover the copper surface to prevent secondary oxidation. This results in a completely environmentally friendly flux that meets the enterprise's wastewater discharge standards in terms of pH and rapid microbial degradation. This effectively solves the problem that traditional environmentally friendly flux wastewater discharge cannot meet the requirements of a pH of 6-9 and rapid microbial degradation in enterprise wastewater, significantly reducing the cost of flux wastewater treatment. It is suitable for the most common low-temperature inlay soldering (WIC) products, and the obtained WIC products have extremely low surface residue. The preparation process is simple and controllable, making it suitable for mass production.

[0046] Among them, short-chain alkyl glycosides can be of a single chain length, such as hexyl glycoside (chain length 6) and dodecyl glycoside (chain length 12); or they can be of mixed chain lengths, such as cocoyl glucoside (chain length 8~14) and octyl-decyl glucoside (chain length 8~10).

[0047] Under different flux application environments, short-chain alkyl glycosides can be replaced with rhamnose esters. After replacement, when performing inlay soldering, the solder temperature range of 250~350℃ should be changed to 250~300℃. Xanthan gum can be directly replaced with sodium alginate, acrylamide, or modified starch.

[0048] In addition to deionized water, short-chain alkyl glycosides, xanthan gum, polyethylene glycol PEG-400, and sodium benzoate, other components such as corrosion inhibitors, matting agents, and film-forming agents can be added to flux under different application environments.

[0049] In steps three and four, the flux will produce a lot of foam due to continuous stirring time. A small amount of defoamer can be added appropriately.

[0050] This invention also provides a method for using a low-temperature embedded welding flux for NbTi superconducting wires, comprising:

[0051] The processed parts are selected according to the WIC wire inlay welding process, and the processed parts include NbTi / Cu round wire and copper groove wire;

[0052] The low-temperature embedded welding flux for the NbTi superconducting wire is added to the flux bath;

[0053] The NbTi / Cu round wire and copper groove wire are pressed into the deoxidation tank and the flux tank in sequence. The low-temperature inlay welding flux of the NbTi superconducting wire is submerged in the NbTi / Cu round wire and the copper groove wire in the flux tank.

[0054] The NbTi / Cu round wire and copper channel wire, coated with the NbTi superconducting low-temperature inlay welding flux, are sequentially pressed into a soldering device, a cooling water tank, a traction machine, an eddy current flaw detector, and a take-up machine. The soldering device welds the NbTi / Cu round wire and copper channel wire to obtain NbTi superconducting wire. The eddy current flaw detector detects the inlay welding effect of the NbTi superconducting wire.

[0055] For example, such as Figure 2 As shown, the processed parts are selected according to the WIC structural wire inlay welding process. The processed parts include NbTi / Cu round wires and copper channel wires of corresponding specifications (such as...). Figure 3 , 4 As shown); The solder temperature and stretching speed are set according to the inlay soldering process requirements. The solder temperature range is 250~350℃, and the stretching speed range is 20~80m / min. The obtained flux is added to the flux tank. The NbTi / Cu round wire and copper channel wire are sequentially passed through the deoxidation tank, flux tank, soldering device, inlay soldering mold, cooling water tank, traction machine, eddy current flaw detector, and take-up machine. The obtained flux is added to the flux tank until it covers the copper channel wire and round wire, and partial length inlay soldering is performed. The inlay soldering effect is evaluated by the eddy current flaw detection results. The surface of the WIC structural wire is required to have a smooth tin plating (e.g., Figure 5 As shown in the figure, no missing solder joints are allowed within 500m.

[0056] In one possible embodiment, an example is provided:

[0057] Example 1:

[0058] Step 1: Select and weigh the raw materials according to the preparation process of the completely environmentally friendly flux for low-temperature siding soldering of NbTi superconducting wires. Prepare 40L of completely environmentally friendly flux. Weigh the following: deionized water (98% specific gravity, 75% concentration); hexyl glucoside (6-chain length, 0.8% specific gravity); xanthan gum (0.8% specific gravity); PEG-400 (0.2% specific gravity); sodium benzoate (0.2% specific gravity).

[0059] Step 2: Heat the deionized water selected in Step 1 to 50°C and begin preparing the completely environmentally friendly flux.

[0060] Step 3: Preheat the hexyl glucoside and PEG-400 selected in Step 1 in water at 50°C for 30 seconds.

[0061] Step 4: Stir the 50℃ hot water obtained in Step 2 at 150r / min, and slowly add the preheated hexyl glucoside and PEG-400 obtained in Step 3 to the hot water in sequence, stirring for 3min each.

[0062] Step 5: Slowly add the xanthan gum and sodium benzoate selected in Step 1 to the solution obtained in Step 4, and stir for 3 minutes each to obtain a completely environmentally friendly flux.

[0063] Step 6: Select 1100m of NbTi / Cu round wire with a diameter of 0.62mm, a width of 2.23mm, a height of 1.42mm, and a groove width of 0.66mm, according to the WIC wire inlay soldering process.

[0064] Step 7: Set the solder temperature to 250℃ and the stretching speed to 80m / min according to the requirements of the inlay welding process. Pass the NbTi / Cu round wire and copper channel wire selected in Step 6 through the deoxidation tank, flux tank, soldering device, inlay welding mold, cooling water tank, traction machine, eddy current flaw detector, and take-up machine in sequence. The size of the inlay welding mold is 2.16×1.36mm. Add the completely environmentally friendly flux obtained in Step 5 to the flux tank until it covers the copper channel wire and round wire. Continuously inlay weld 1000m of wire.

[0065] Step 8: Observe the surface quality of the WIC wire. There are no solder nodules on the surface, and the tin plating is smooth. Check the eddy current testing results of the 1000m wire obtained in Step 7. The number of eddy current alarm signals corresponding to the missing solder joints is 0.

[0066] Example 2:

[0067] Step 1: Select and weigh the raw materials according to the preparation process of the completely environmentally friendly flux for low-temperature siding soldering of NbTi superconducting wires, and prepare 30L of completely environmentally friendly flux. Weigh the following: deionized water (99% specific gravity, 50% concentration); dodecyl glycoside (12-chain length, 0.4% specific gravity); xanthan gum (0.4% specific gravity); PEG-400 (0.1% specific gravity); and sodium benzoate (0.1% specific gravity).

[0068] Step 2: Heat the deionized water selected in Step 1 to 60°C and begin preparing the completely environmentally friendly flux.

[0069] Step 3: Preheat the dodecyl glycoside and PEG-400 selected in Step 1 in water at 60°C for 60 seconds.

[0070] Step 4: Stir the 60℃ hot water obtained in Step 2 at 100r / min, and slowly add the preheated dodecyl glycoside and PEG-400 obtained in Step 3 to the hot water in sequence, stirring for 5min each.

[0071] Step 5: Slowly add the xanthan gum and sodium benzoate selected in Step 1 to the solution obtained in Step 4, and stir for 5 minutes each to obtain a completely environmentally friendly flux.

[0072] Step 6: Select 1100m of NbTi / Cu round wire with a diameter of 1.72mm, a width of 3.70mm, a height of 2.85mm, and a groove width of 1.73mm, according to the WIC wire inlay soldering process.

[0073] Step 7: Set the solder temperature to 350℃ and the stretching speed to 20m / min according to the requirements of the inlay welding process. Pass the NbTi / Cu round wire and copper channel wire selected in Step 6 through the deoxidation tank, flux tank, soldering device, inlay welding mold, cooling water tank, traction machine, eddy current flaw detector, and take-up machine in sequence. The size of the inlay welding mold is 3.62×2.81mm. Add the completely environmentally friendly flux obtained in Step 5 to the flux tank until it covers the copper channel wire and round wire. Continuously inlay weld 1000m of wire.

[0074] Step 8: Observe the surface quality of the WIC wire. There are no solder nodules on the surface, and the tin plating is smooth. Check the eddy current testing results of the 1000m wire obtained in Step 7. The number of eddy current alarm signals corresponding to the missing solder joints is 0.

[0075] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0076] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for using a low-temperature embedded welding flux for NbTi superconducting wires, characterized in that, include: The processed parts are selected according to the WIC wire inlay welding process, and the processed parts include NbTi / Cu round wire and copper groove wire; The low-temperature embedded welding flux for the NbTi superconducting wire is added to the flux bath; The NbTi / Cu round wire and copper groove wire are pressed into the deoxidation tank and the flux tank in sequence. The low-temperature inlay welding flux of the NbTi superconducting wire is submerged in the NbTi / Cu round wire and the copper groove wire in the flux tank. The NbTi / Cu round wire and copper channel wire, coated with the NbTi superconducting low-temperature inlay welding flux, are sequentially pressed into a soldering device, a cooling water tank, a traction machine, an eddy current flaw detector, and a take-up machine. The soldering device welds the NbTi / Cu round wire and copper channel wire to obtain NbTi superconducting wire. The eddy current flaw detector detects the inlay welding effect of the NbTi superconducting wire. The preparation of the NbTi superconducting wire low-temperature embedded welding flux includes: Step 1: Heat the deionized water to 50-60 degrees Celsius; Step 2: Heat the short-chain alkyl glycoside and polyethylene glycol separately in a water bath at 50-60 degrees Celsius for 30-60 seconds. Step 3: Stir the preheated deionized water obtained in Step 1 at 100~150 r / min, and simultaneously add the short-chain alkyl glycoside and polyethylene glycol obtained in Step 2. Step 4: Add xanthan gum and sodium benzoate sequentially to the solution obtained in Step 3 to prepare flux; The proportions of deionized water, short-chain alkyl glycosides, xanthan gum, polyethylene glycol, and sodium benzoate in the flux are as follows: deionized water 98%-99%, short-chain alkyl glycosides 0.4%-0.8%, xanthan gum 0.4%-0.8%, polyethylene glycol 0.1%-0.2%, and sodium benzoate 0.1%-0.2%. The short-chain alkyl glycosides have a chain length of C6-C14. The preheated deionized water obtained in step one is stirred at 100-150 r / min, while the short-chain alkyl glycoside and polyethylene glycol obtained in step two are added. The short-chain alkyl glycoside and polyethylene glycol obtained by heating in step two are added sequentially to the preheated deionized water. The single preparation volume of the solution formed by adding the short-chain alkyl glycoside and polyethylene glycol to the deionized water is less than 50L. The single preparation after adding the short-chain alkyl glycoside and polyethylene glycol is stirred for 3-5 minutes. The stirring time is extended as the single preparation volume increases.

2. The method of using a low-temperature embedded welding flux for NbTi superconducting wires according to claim 1, characterized in that, The short-chain alkyl glycoside is one of a single-chain long-short-chain alkyl glycoside or a mixed-chain long-short-chain alkyl glycoside.

3. The method of using a low-temperature embedded welding flux for NbTi superconducting wires according to claim 1, characterized in that, The short-chain alkyl glycoside is replaced with rhamnose ester, and the xanthan gum is replaced with one or more of sodium alginate, acrylamide, and modified starch.

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