A high-corrosion-resistance and high-strength solder and its preparation method

Abstract

The present invention relates to the field of welding technology, and particularly to a high corrosion-resistant and high-strength solder and a preparation method thereof. The solder includes a filler metal and a soldering flux. The filler metal includes: 40 - 55 parts of aluminum, 12 - 16 parts of aluminum-silicon alloy, 27 - 33 parts of copper, 0.5 - 5 parts of germanium, 0.6 - 1 part of manganese, 0.2 - 0.6 part of titanium, 2 - 5 parts of tin, and 0.1 - 0.5 part of rare earth element; the soldering flux includes: 25 - 50 parts of potassium chloride, 10 - 35 parts of sodium chloride, 4.0 - 30.0 parts of lithium chloride, 10 - 20 parts of potassium fluoride-aluminum fluoride complex, 0.5 - 6 parts of zinc chloride, 2 - 6 parts of zinc fluoride, 0.05 - 3 parts of sodium fluoride, 0.05 - 3 parts of lithium fluoride, 0.05 - 2 parts of potassium hexafluorosilicate, and 0.05 - 1.5 parts of potassium hydrogen fluoride. Through the mutual cooperation of the filler metal and the soldering flux, the strength, corrosion resistance, and stability of the welded joint are jointly improved.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and particularly to a highly corrosion-resistant and high-strength solder and a preparation method thereof. Background Art

[0002] In the field of modern industrial manufacturing, welding, as a key connection technology, is widely used in many industries such as aerospace, automotive manufacturing, electronic equipment, and mechanical engineering. With the continuous improvement of product performance requirements in various industries, more stringent challenges have been posed to the performance of solders. Solders with high corrosion resistance and high strength have become the key research and development directions.

[0003] Traditional solders have many deficiencies in terms of corrosion resistance and strength. In many application scenarios, especially in harsh working environments such as high temperature, high humidity, strong acid and alkali conditions, ordinary solders are easily corroded, resulting in solder joint failure, seriously affecting the service life and reliability of products. For example, in the aerospace field, when an aircraft is flying at high altitude, it will face extreme temperature changes, high humidity, and corrosive gases in the atmosphere. If solders with poor corrosion resistance are used, the solder joints are extremely easy to be corroded, thus endangering flight safety. In automotive manufacturing, automotive components are exposed to the outdoor environment for a long time, and are eroded by rainwater, salt, dust, etc. The parts connected by ordinary solders are easy to rust and corrode, reducing the strength and performance of the components and increasing the maintenance cost. In terms of strength, the strength of traditional solders often cannot meet some applications with higher requirements for structural strength. For example, in mechanical engineering, the connection of key components of large mechanical equipment needs to withstand huge loads and stresses. If the solder strength is insufficient, the solder joints are prone to fracture under long-term mechanical stress, resulting in equipment failure and affecting production efficiency.

[0004] In order to improve the corrosion resistance of solders, some corrosion-resistant elements are usually added to the solders, but the addition of these elements often has a negative impact on other properties of the solders, such as reducing the wettability and fluidity of welding and affecting the welding quality. And methods to improve the strength of solders, such as changing the alloy composition or performing heat treatment, may also bring problems such as increasing costs and reducing toughness.

[0005] The Chinese invention patent with application number CN202411448985.4 discloses a high-strength and high-elongation SnPbSbInAu alloy solder and its preparation method. The alloy solder is composed of: Pb 33.0-36.5wt%, Sb 2.0-4.0wt%, In1.5-3.5wt%, Au 2.0-3.5wt%, P 0.005-0.012wt%, and the balance is Sn. The solder has a solid-liquid phase temperature of 180℃-185℃ and has the advantages of high elongation, high strength, high creep resistance, and excellent low-temperature service performance. However, its corrosion resistance is insufficient and it contains lead (Pb), which does not meet the current environmental protection and health requirements. Its high cost, complex preparation process, environmental and health issues and other defects limit its wide application.

[0006] The Chinese invention patent with application number CN202411527146.1 discloses an Ag-Cu-Ti-Zr-B active composite solder and its preparation method. The active composite solder is composed of the following mass percentage components: 5-8% Ti, 2-5% Zr, 0.1-2% B, and the balance is Ag-28Cu eutectic composition. The active composite solder has many advantages such as improved wettability, enhanced interface bonding strength, refined joint structure, and reduced brazing temperature. However, its thermal stability is insufficient, and its wettability and fluidity still need to be further improved. Wettability and fluidity directly affect the mechanical strength and corrosion resistance of the welded joint.

[0007] In summary, developing a solder with high welding strength and high corrosion resistance has become an urgent problem to be solved. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a high-corrosion-resistant and high-strength solder and a preparation method thereof, wherein the solder improves the strength, corrosion resistance and stability of the welded joint by the cooperation of the solder and the flux. The preparation method adopts a structural design in which the solder wraps the flux, ensuring that the flux is evenly released during the welding process, improving the welding quality and achieving precise welding control.

[0009] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0010] A high-corrosion-resistant and high-strength solder, comprising a solder and a brazing agent, wherein the solder comprises the following raw materials by weight: 40-55 parts of aluminum, 12-16 parts of aluminum silicon alloy, 27-33 parts of copper, 0.5-5 parts of germanium, 0.6-1 parts of manganese, 0.2-0.6 parts of titanium, 2-5 parts of tin, and 0.1-0.5 parts of rare earth elements;

[0011] The soldering flux comprises the following raw materials by weight parts: 25 - 50 parts of potassium chloride, 10 - 35 parts of sodium chloride, 4.0 - 30.0 parts of lithium chloride, 10 - 20 parts of potassium fluoride - aluminum fluoride complex, 0.5 - 6 parts of zinc chloride, 2 - 6 parts of zinc fluoride, 0.05 - 3 parts of sodium fluoride, 0.05 - 3 parts of lithium fluoride, 0.05 - 2 parts of potassium hexafluorosilicate, and 0.05 - 1.5 parts of potassium bifluoride.

[0012] The above - mentioned high - corrosion - resistance and high - strength solder has significant performance advantages. The combination of its raw material components improves the welding strength, corrosion resistance and other comprehensive welding properties through synergistic effects. The combination of main components such as aluminum, aluminum - silicon alloy and copper in the solder provides good mechanical properties. The addition of aluminum - silicon alloy reduces the melting point of the solder, while improving its thermal cracking resistance and wettability. The addition of copper significantly improves the strength of the solder. The addition of manganese further optimizes the microstructure of the solder and improves its tensile strength. The addition of trace elements such as germanium and titanium further optimizes the microstructure of the solder, improves its fluidity and wettability, enabling it to better fill the weld seam during the welding process, and further improving the tensile strength, hardness and corrosion resistance of the weld. The addition of rare earth elements (such as lanthanum or cerium) significantly improves the corrosion resistance of the solder. Rare earth elements can form a dense oxide film on the surface of the solder, effectively blocking the corrosive medium. The addition of tin further improves the corrosion resistance of the solder, enhances its fluidity and wettability, while maintaining good strength.

[0013] In the above - mentioned soldering flux, chlorides such as potassium chloride, sodium chloride and lithium chloride, as the basic components, have low melting points and good fluidity. They can effectively remove the oxide films on the surfaces of the base material and the solder, and at the same time form a liquid thin layer during the welding process, covering the metal surface to prevent further oxidation. Fluorides have strong film - removing ability and can dissolve metal oxides, especially having a significant effect on removing the oxide films of metals such as aluminum and magnesium. The addition of lithium chloride (LiCl) and lithium fluoride (LiF) can adjust the melting point of the soldering flux. 2 ), zinc chloride (ZnCl 2 ), can reduce the melting temperature of the soldering flux, while providing good wettability and fluidity. These components can promote the flow and spreading of the solder, and help the solder better fill the weld seam during the welding process. Potassium hexafluorosilicate (K 2 SiF 6 ), and potassium bifluoride (KHF 2 ) can form a dense protective layer during the welding process to prevent the corrosion of the welded joint. Sodium fluoride (NaF) and lithium fluoride (LiF) not only have a film - removing effect, but also can form stable compounds during the welding process, further improving the corrosion resistance of the welded joint.

[0014] By reasonably proportioning chlorides and fluorides, the soldering flux can melt at a lower temperature and cover the welding surface, reducing the oxidation of the base metal, while improving the wettability and spreadability of the filler metal. The fluorides and chlorides in the soldering flux can reduce the interfacial tension of the liquid filler metal, promote the bonding between the filler metal and the base metal, thereby increasing the strength of the welded joint. The protective layer formed by fluorides and chlorides can effectively prevent the corrosion of the welded joint. Through the synergistic effect of each component, the above-mentioned soldering flux can better remove the oxide film and optimize the wettability of the filler metal, thereby increasing the strength of the welded joint.

[0015] Preferably, the potassium fluoride-aluminum fluoride composite comprises the following raw materials by weight parts: 35-45 parts of potassium fluoride, 35-45 parts of aluminum fluoride, 5-8 parts of a dopant, and 10-15 parts of a coating material.

[0016] Preferably, the dopant is one or more of magnesium fluoride, cerium trifluoride, and lanthanum fluoride.

[0017] Preferably, the coating material is one or more of aluminum fluoride, lithium fluoride, and magnesium fluoride.

[0018] Preferably, the rare earth element is one or two of lanthanum and cerium.

[0019] Preferably, the preparation method of the potassium fluoride-aluminum fluoride composite is as follows:

[0020] S1, dry ball-mill potassium fluoride and aluminum fluoride, with a ball-to-material ratio of 10-15:1, a ball-milling time of 1-2 h, and a rotation speed of 300-400 revolutions per minute to make them mix evenly;

[0021] S2, add the dopant to the material mixture obtained in step S1, add absolute ethanol as a dispersant, and grind for 30-60 minutes to make the dopant evenly distributed. The dosage of absolute ethanol is 10%-20% of the total mass of the dopant and the material mixture obtained in step S1;

[0022] S3, sinter the mixture ground in step S2 at a temperature of 600-800 °C, keep it warm for 2-3 h under an argon protection atmosphere, then naturally cool it to room temperature, take out the sintered material, wash it with deionized water to remove surface impurities, and then dry it at a temperature of 70-90 °C for 10-14 h to obtain composite 1;

[0023] S4, add the coating material to deionized water, stir evenly to form a suspension, mix composite 1 with the suspension to obtain a slurry with a solid content of 20%-40%, atomize the slurry into small droplets, and then dry it with hot air. The inlet air temperature of the hot air is 150-250 °C, and the outlet air temperature is 100-150 °C. After the evaporation of deionized water, dry coated composite particles are obtained;

[0024] S5. Subject the dried coated composite particles to high-temperature treatment in an inert gas atmosphere at a temperature of 300 - 500 °C for 1.5 - 3 h.

[0025] The composite formed by potassium fluoride (KF) and aluminum fluoride (AlF 3 ) has a lower melting temperature and better fluidity compared with single potassium fluoride or aluminum fluoride. This enables the welding process to be carried out at a lower temperature, which not only reduces energy consumption but also decreases the thermal damage to the base material during welding. After melting, it forms a molten salt with low viscosity, and the good fluidity enables the composite to better wet the surface of the base material during welding and cover the welding surface more evenly, thus improving the welding quality. The composite of potassium fluoride and aluminum fluoride can effectively remove the oxide film on the surface of the base material at high temperature. Especially when welding aluminum and its alloys, this composite can rapidly dissolve the alumina layer and promote good bonding between the filler metal and the base material. The addition of dopants (such as magnesium fluoride, cerium trifluoride, lanthanum fluoride) and rare earth elements (such as lanthanum, cerium) can significantly improve the performance of the potassium fluoride and aluminum fluoride composite in removing the oxide film and enhancing the properties of the welded joint: the fluorides in the dopants can effectively remove the oxide film on the metal surface during welding. Rare earth elements such as lanthanum and cerium have good adsorption properties and can combine with oxides to form more stable compounds, thus promoting the removal of the oxide film. Rare earth elements can also improve the tensile strength and toughness of the welded joint by changing the microstructure of the weld metal. The fluorides in the dopants can not only remove the oxide film during welding but also improve the wettability and formability of the weld, enhancing the bonding ability between the metal and the flux. In addition, the fluorides can enhance the mechanical properties of the welding material by forming a stable fluoride ion bridging structure. Components such as lithium fluoride in the coating material can lower the melting point of the composite and improve its fluidity. The coating layer can improve the surface properties of the composite, making it have better wettability and fluidity during welding. Moreover, through the coating treatment, the performance of the composite is more stable and it can better play the roles of film removal, wetting, and gap filling during welding. The coating layer forms an effective protective layer, also improving its corrosion resistance. Further, the coating material is subjected to high-temperature treatment in an inert gas atmosphere. The inert atmosphere heat treatment can maintain the integrity and characteristics of the material at high temperature, prevent oxidation, and at the same time, its surface characteristics will be significantly improved, contributing to enhancing the thermal stability, mechanical properties, and corrosion resistance of the material.

[0026] The preparation method of the above high-corrosion-resistance and high-strength solder includes the following steps:

[0027] Step 1. Melting the solder raw materials at 700 - 800 °C for 30 - 80 min;

[0028] Step 2: Cast, cool, and roll the melted filler metal alloy into a strip, and then process the strip-shaped filler metal into a U-shaped groove.

[0029] Step 3: Mix and crush the flux raw materials evenly by ball milling to obtain a flux powder with a particle size of 20 - 30 μm. Step 4: Pour the flux powder into the U-shaped groove of the strip-shaped filler metal, and then close the U-shaped groove of the strip-shaped filler metal by rolling to obtain the product.

[0030] Preferably, the thickness of the strip-shaped filler metal in Step 2 is 0.5 - 1 mm.

[0031] Preferably, in Step 3, the ball-to-material ratio during ball milling is 15 - 20:1, and the rotation speed is 350 - 450 r / min.

[0032] Preferably, stretch the high corrosion-resistant and high-strength solder obtained in Step 4 into a filament with a diameter of 0.3 - 0.6 mm.

[0033] The present invention has the following beneficial effects:

[0034] The filler metal of the present invention provides good basic strength through the reasonable proportion of metals such as aluminum and copper, and the addition of elements such as titanium and manganese helps to refine the grains and further improve the strength. Aluminum itself has certain corrosion resistance, and the addition of germanium can enhance its corrosion resistance in a specific environment. Rare earth elements can also improve the properties of the surface oxide film and increase the corrosion resistance. The reasonable combination of each component makes the filler metal have good wettability and fluidity, which is convenient for welding operations. Moreover, the synergistic effect of each raw material component significantly improves the welding strength, corrosion resistance, and other comprehensive welding performances, and is suitable for high-performance welding requirements. The flux of the present invention achieves good comprehensive performance in terms of deoxidation ability, thermal stability, corrosion resistance, welding strength, etc. through the reasonable proportion of various chlorides and fluorides and their synergistic effect. It can effectively remove the oxides on the metal surface, form high-strength welds, and also improve the corrosion resistance. The filler metal and flux of the present invention cooperate with each other to jointly improve the comprehensive strength and stability of the welded joint.

[0035] Furthermore, the application of the potassium fluoride-aluminum fluoride complex of the present invention in a soldering flux has significant advantages. Compared with a mixture of single potassium fluoride and aluminum fluoride, the complex can significantly reduce the melting temperature, improve the stability and reliability of the welding process, and particularly has good effects in enhancing wettability, fluidity, film removal ability, and the quality of the welded joint. The addition of dopants (such as magnesium fluoride, cerium trifluoride, lanthanum fluoride) further enhances the chemical activity of the complex, making it perform better in removing oxide films. Rare earth elements (such as lanthanum and cerium) further optimize the properties of the welded joint, improving its corrosion resistance and strength. The potassium fluoride-aluminum fluoride complex has high thermal stability and can maintain good chemical properties at high temperatures. This makes the complex not easily decomposed during the welding process, thus ensuring the stability and reliability of the welding process. High-temperature treatment in an inert gas environment helps to further improve the thermal stability and mechanical properties of the material. High-temperature treatment of the coating material in an inert gas atmosphere improves the material properties, protects the material integrity, optimizes the surface characteristics, and enhances the thermal stability and mechanical properties.

[0036] The preparation method of the present invention adopts a structural design of wrapping the soldering flux with the filler metal, ensuring the uniform distribution and precise control of the filler metal and the soldering flux, ensuring the uniform release of the soldering flux during the welding process, improving the welding quality, stretching it into a filamentous structure for convenient welding operation, and at the same time, further achieving precise welding control. This preparation method ensures the stability and consistency of the product quality, and is easy to operate and suitable for mass production. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0038] The raw materials used in the following examples are all ordinary commercially available products. Among them, in the solder raw materials, the aluminum ingot has a purity of 99.85%; the aluminum-silicon alloy is aluminum-silicon 20 from Shanghai Qichen Industrial Co., Ltd.; the copper has a purity of 99.97%; the germanium is germanium grains of 1-15 mm with a purity of 99.9%; the manganese is manganese flakes with a content of 99.7%: the titanium has a purity of 99.99%; the tin has a purity of 99.99%; the lanthanum has a purity of 99.9%; the cerium has a purity of 99.9%; potassium chloride is a white powder with a mesh size of 90 from Sichuan Xinyun Jinhong Technology Co., Ltd.; sodium chloride is crystal particles with a mesh size of 50 from Henan Tuohong Chemical Co., Ltd.; lithium chloride has an active ingredient content of 99% and is a white crystal from Jinan Yunuo Chemical Co., Ltd.; zinc chloride is a white crystalline powder with a purity of 98% from Sichuan Chengzhu Biotechnology Co., Ltd.; zinc fluoride is a white powder with a purity of 99%; sodium fluoride is a white crystalline powder with a purity of 99%; lithium fluoride is a white powder with a purity of 99%; potassium hexafluorosilicate (K 2 SiF 6 ), a white crystalline powder with a purity of 99%; potassium bifluoride is a white crystalline powder with a purity of 99%; potassium fluoride is a white crystalline powder with a purity of 99% from Shandong Yuxuan Chemical Products Co., Ltd.; aluminum fluoride has a purity of 99% and is a white crystalline powder from Langfang Qianyao Technology Co., Ltd.; magnesium fluoride is a colorless crystal or white powder with a purity of 99% from Langfang Qianyao Technology Co., Ltd.; cerium trifluoride is a 300-mesh powder with an active ingredient content of 99.99% from Shandong Desheng New Materials Co., Ltd.; lanthanum fluoride (LaF 3 ), a white crystalline powder with a purity of 99% from Shandong Haoyao New Materials Co., Ltd. Example 1

[0039] A high corrosion-resistant and high-strength solder, including a solder and a soldering flux. The solder includes the following raw materials by weight: 50 parts of aluminum, 14 parts of aluminum-silicon alloy, 30 parts of copper, 3 parts of germanium, 0.8 part of manganese, 0.4 part of titanium, 3 parts of tin, 0.15 part of lanthanum, and 0.15 part of cerium.

[0040] The soldering flux includes the following raw materials by weight: 40 parts of potassium chloride, 26 parts of sodium chloride, 20 parts of lithium chloride, 14 parts of potassium fluoride-aluminum fluoride complex, 3 parts of zinc chloride, 5 parts of zinc fluoride, 2 parts of sodium fluoride, 2 parts of lithium fluoride, 1 part of potassium hexafluorosilicate (K 2 SiF 6 ), and 0.8 part of potassium bifluoride (KHF 2 ).

[0041] The potassium fluoride-aluminum fluoride complex includes the following raw materials by weight: 40 parts of potassium fluoride, 40 parts of aluminum fluoride, 6 parts of a dopant, and 12 parts of a coating material. The dopant is magnesium fluoride, cerium trifluoride, lanthanum fluoride (LaF 3), with a weight ratio of 1:1.2:1, and the coating material is lithium fluoride and magnesium fluoride, with a weight ratio of 1:1.

[0042] The preparation method of the potassium fluoride-aluminum fluoride composite is as follows:

[0043] S1. Put potassium fluoride and aluminum fluoride into a ball mill for dry ball milling. The ball-to-material ratio is 12:1, the ball milling time is 1.8 h, and the rotation speed is 350 revolutions per minute to make them evenly mixed;

[0044] S2. Add the dopant to the material after mixing in step S1, add anhydrous ethanol as a dispersant, and grind for 45 minutes to make the dopant evenly distributed. The dosage of anhydrous ethanol is 15% of the total mass of the dopant and the material after mixing in step S1;

[0045] S3. Put the mixture ground in step S2 into a crucible, place it in a tubular furnace for sintering. Heat it to 700 °C at a heating rate of 5 °C / min, keep it warm for 2.5 h under an argon protection atmosphere, then naturally cool it to room temperature. Take out the sintered material, wash it with deionized water to remove surface impurities, and then dry it at 82 °C for 11 h to obtain composite 1;

[0046] S4. Add the coating material to deionized water, stir evenly to form a uniform suspension. Mix composite 1 with the suspension to obtain a slurry with a solid content of 30%. Atomize the slurry into tiny droplets through the nozzle of a spray drying device and spray it into a drying chamber for drying. Hot air is introduced into the drying chamber, the inlet air temperature is 200 °C, and the outlet air temperature is 120 °C. After the hot air contacts the droplets, the deionized water quickly evaporates to form dry coated composite particles. The dried coated composite particles are separated and collected from the gas stream by a cyclone separator;

[0047] S5. Perform high-temperature treatment on the dried coated composite particles in an inert gas atmosphere at a temperature of 450 °C for 2.5 h.

[0048] The preparation method of the above high-corrosion-resistance and high-strength solder includes the following steps:

[0049] Step 1. Melt the solder raw materials at 750 °C for 50 min;

[0050] Step 2. Cast, cool, and roll the melted solder alloy into a strip with a thickness of 0.7 mm, and then process the strip-shaped solder into a U-shaped groove;

[0051] Step 3. Use ball milling to evenly mix and crush the flux raw materials to obtain a flux powder with a particle size of 25 μm. The ball-to-material ratio during ball milling is 20:1 and the rotation speed is 400 r / min;

[0052] Step 4: Pour the flux powder into the U-shaped groove, then close the U-shaped groove of the strip solder by rolling, and then stretch it into a filament with a diameter of 0.5 mm to obtain the product. Example 2

[0053] A highly corrosion-resistant and high-strength solder, comprising a solder and a flux. The solder comprises the following raw materials by weight: 40 parts of aluminum, 16 parts of aluminum-silicon alloy, 33 parts of copper, 5 parts of germanium, 1 part of manganese, 0.5 part of titanium, 2 parts of tin, 0.06 part of lanthanum, and 0.04 part of cerium.

[0054] The flux comprises the following raw materials by weight: 25 parts of potassium chloride, 35 parts of sodium chloride, 4 parts of lithium chloride, 17 parts of potassium fluoride-aluminum fluoride complex, 0.5 part of zinc chloride, 4 parts of zinc fluoride, 0.05 part of sodium fluoride, 3 parts of lithium fluoride, 0.05 - 2 parts of potassium hexafluorosilicate, and 0.05 part of potassium bifluoride.

[0055] The potassium fluoride-aluminum fluoride complex comprises the following raw materials by weight: 45 parts of potassium fluoride, 35 parts of aluminum fluoride, 5 parts of dopant, and 10 parts of coating material. The dopant is magnesium fluoride, cerium trifluoride, lanthanum fluoride (LaF 3 ), and the weight ratio is 1:1.5:2. The coating material is lithium fluoride and magnesium fluoride, and the weight ratio is 1:2.

[0056] The preparation method of the potassium fluoride-aluminum fluoride complex is as follows:

[0057] S1: Put potassium fluoride and aluminum fluoride into a ball mill for dry ball milling. The ball-to-material ratio is 10:1, the ball milling time is 1.5 h, and the rotation speed is 400 revolutions per minute to make them mix evenly;

[0058] S2: Add the dopant to the material after mixing in step S1, add anhydrous ethanol as a dispersant, and grind for 30 minutes to make the dopant evenly distributed. The dosage of anhydrous ethanol is 10% of the total mass of the dopant and the material after mixing in step S1;

[0059] S3: Put the mixture after grinding in step S2 into a crucible, place it in a tube furnace for sintering, heat it to 600 °C at a heating rate of 5 °C / min, keep it warm for 3 h under an argon protection atmosphere, then naturally cool it to room temperature, take out the sintered material, wash it with deionized water to remove surface impurities, and then dry it at 80 °C for 12 h to obtain Complex 1;

[0060] S4. Add the coating material into deionized water, stir evenly to form a uniform suspension, mix Complex 1 with the suspension to obtain a slurry with a solid content of 20%. Atomize the slurry into tiny droplets through the nozzle of a spray drying device, spray it into a drying chamber for drying. Hot air is introduced into the drying chamber, with an inlet air temperature of 150 °C and an outlet air temperature of 100 °C. After the hot air contacts the droplets, the deionized water quickly evaporates to form dry coated composite particles. The dried coated composite particles are separated and collected from the air stream by a cyclone separator;

[0061] S5. Perform high-temperature treatment on the dried coated composite particles in an inert gas atmosphere at a temperature of 400 °C for 2 h.

[0062] The preparation method of the above high-corrosion-resistance and high-strength solder includes the following steps:

[0063] Step 1. Melt the solder raw materials at 800 °C for 40 min;

[0064] Step 2. Cast, cool, and roll the melted solder alloy into a strip with a thickness of 0.8 mm, and then process the strip solder into a U-shaped groove;

[0065] Step 3. Mix and crush the flux raw materials evenly by ball milling to obtain a flux powder with a particle size of 20 μm. The ball-to-material ratio during ball milling is 18:1 and the rotation speed is 350 r / min;

[0066] Step 4. Pour the flux powder into the U-shaped groove, then close the U-shaped groove of the strip solder by rolling, and then stretch it into a filament with a diameter of 0.4 mm, thus obtaining the product. Example 3

[0067] A high-corrosion-resistance and high-strength solder, including a solder and a flux. The solder includes the following raw materials by weight: 55 parts of aluminum, 12 parts of aluminum-silicon alloy, 27 parts of copper, 0.5 part of germanium, 0.6 part of manganese, 0.2 part of titanium, 4 parts of tin, 0.4 part of lanthanum, and 0.1 part of cerium.

[0068] The flux includes the following raw materials by weight: 50 parts of potassium chloride, 10 parts of sodium chloride, 30 parts of lithium chloride, 10 parts of potassium fluoride-aluminum fluoride complex, 6 parts of zinc chloride, 2 parts of zinc fluoride, 3 parts of sodium fluoride, 1 part of lithium fluoride, 0.05 - 2 parts of potassium hexafluorosilicate, and 1.5 parts of potassium hydrogen fluoride.

[0069] The potassium fluoride-aluminum fluoride complex includes the following raw materials by weight: 35 parts of potassium fluoride, 45 parts of aluminum fluoride, 8 parts of a dopant, and 15 parts of a coating material. The dopant is magnesium fluoride, cerium trifluoride, lanthanum fluoride (LaF 3), with a weight ratio of 1:2:1, and the coating material is lithium fluoride and magnesium fluoride with a weight ratio of 1:0.5.

[0070] The preparation method of the potassium fluoride-aluminum fluoride composite is as follows:

[0071] S1. Put potassium fluoride and aluminum fluoride into a ball mill for dry ball milling. The ball-to-material ratio is 15:1, the ball milling time is 2 h, and the rotation speed is 300 revolutions per minute to make them evenly mixed.

[0072] S2. Add the dopant to the material mixture obtained in step S1, add absolute ethanol as a dispersant, and grind for 60 minutes to make the dopant evenly distributed. The dosage of absolute ethanol is 20% of the total mass of the dopant and the material mixture obtained in step S1.

[0073] S3. Put the mixture ground in step S2 into a crucible, place it in a tube furnace for sintering, heat it to 800 °C at a heating rate of 5 °C / min, keep it warm for 2 h under an argon protection atmosphere, then naturally cool it to room temperature. Take out the sintered material, wash it with deionized water to remove surface impurities, and then dry it at 90 °C for 10 h to obtain composite 1.

[0074] S4. Add the coating material to deionized water, stir evenly to form a uniform suspension. Mix composite 1 with the suspension to obtain a slurry with a solid content of 40%. Atomize the slurry into tiny droplets through the nozzle of a spray drying device and spray it into a drying chamber for drying. Hot air is introduced into the drying chamber, the inlet air temperature is 250 °C, and the outlet air temperature is 150 °C. After the hot air contacts the droplets, the deionized water quickly evaporates to form dry coated composite particles. The dried coated composite particles are separated and collected from the gas stream through a bag filter.

[0075] S5. Perform high-temperature treatment on the dried coated composite particles in an inert gas atmosphere at a temperature of 500 °C for 1.5 h.

[0076] The preparation method of the above high-corrosion-resistance and high-strength solder includes the following steps:

[0077] Step 1. Melt the solder raw materials at 700 °C for 80 min.

[0078] Step 2. Cast, cool, and roll the melted solder alloy into a strip with a thickness of 1 mm, and then process the strip-shaped solder into a U-shaped groove.

[0079] Step 3. Use ball milling to evenly mix and crush the flux raw materials to obtain a flux powder with a particle size of 30 μm. The ball-to-material ratio during ball milling is 20:1 and the rotation speed is 450 r / min.

[0080] Step 4: Pour the flux powder into the U-shaped groove, then close the U-shaped groove of the strip solder by rolling, and then stretch it into a filament with a diameter of 0.6 mm to obtain the product. Example 4

[0081] A high corrosion-resistant and high-strength solder, comprising a solder and a flux. The solder comprises the following raw materials in parts by weight: 48 parts of aluminum, 13 parts of aluminum-silicon alloy, 31 parts of copper, 2 parts of germanium, 0.9 part of manganese, 0.6 part of titanium, 5 parts of tin, 0.1 part of lanthanum, and 0.3 part of cerium.

[0082] The flux comprises the following raw materials in parts by weight: 45 parts of potassium chloride, 20 parts of sodium chloride, 18 parts of lithium chloride, 20 parts of potassium fluoride-aluminum fluoride complex, 4 parts of zinc chloride, 6 parts of zinc fluoride, 2.5 parts of sodium fluoride, 0.05 part of lithium fluoride, 0.05 - 2 parts of potassium hexafluorosilicate, and 1.2 parts of potassium bifluoride.

[0083] The potassium fluoride-aluminum fluoride complex comprises the following raw materials in parts by weight: 38 parts of potassium fluoride, 42 parts of aluminum fluoride, 7 parts of dopant, and 14 parts of coating material. The dopant is magnesium fluoride, cerium trifluoride, lanthanum fluoride (LaF 3 ), with a weight ratio of 1:1.5:1.5. The coating material is lithium fluoride and magnesium fluoride, with a weight ratio of 1:1.5.

[0084] The preparation method of the potassium fluoride-aluminum fluoride complex is as follows:

[0085] S1: Put potassium fluoride and aluminum fluoride into a ball mill for dry ball milling. The ball-to-material ratio is 14:1, the ball milling time is 1 h, and the rotation speed is 350 revolutions per minute to make them evenly mixed;

[0086] S2: Add the dopant to the material after mixing in step S1, add anhydrous ethanol as a dispersant, and grind for 50 minutes to make the dopant evenly distributed. The amount of anhydrous ethanol used is 18% of the total mass of the dopant and the material after mixing in step S1;

[0087] S3: Put the mixture after grinding in step S2 into a crucible, place it in a tubular furnace for sintering. Heat it to 650 °C at a heating rate of 5 °C / min, keep it warm for 2.5 h under an argon protection atmosphere, then naturally cool to room temperature. Take out the sintered material, wash it with deionized water to remove surface impurities, and then dry it at 70 °C for 14 h to obtain complex 1;

[0088] S4. Add the coating material into deionized water, stir evenly to form a homogeneous suspension, mix the composite 1 with the suspension to obtain a slurry with a solid content of 35%. Atomize the slurry into tiny droplets through the nozzle of a spray drying device, spray it into a drying chamber for drying. Hot air is introduced into the drying chamber, with an inlet air temperature of 180 °C and an outlet air temperature of 120 °C. After the hot air contacts the droplets, the deionized water evaporates rapidly to form dry coated composite particles. The dried coated composite particles are separated and collected from the airflow by a cyclone separator;

[0089] S5. Perform high-temperature treatment on the dried coated composite particles in an inert gas atmosphere at a temperature of 300 °C for 3 h.

[0090] The preparation method of the above high-corrosion-resistant and high-strength solder includes the following steps:

[0091] Step 1. Melt the solder raw materials at 800 °C for 30 min;

[0092] Step 2. Cast, cool, and roll the melted solder alloy into a strip with a thickness of 0.5 mm, and then process the strip-shaped solder into a U-shaped groove;

[0093] Step 3. Mix and crush the flux raw materials evenly by ball milling to obtain a flux powder with a particle size of 28 μm. The ball-to-material ratio during ball milling is 15:1 and the rotation speed is 400 r / min;

[0094] Step 4. Pour the flux powder into the U-shaped groove, then close the U-shaped groove of the strip-shaped solder by rolling, and then stretch it into a filament with a diameter of 0.3 mm to obtain the product.

[0095] Comparative Example 1

[0096] A high-corrosion-resistant and high-strength solder includes a solder and a flux. The solder includes the following raw materials by weight parts: 50 parts of aluminum, 14 parts of aluminum-silicon alloy, 30 parts of copper, 3 parts of germanium, 0.8 part of manganese, 0.4 part of titanium, and 3 parts of tin.

[0097] The flux includes the following raw materials by weight parts: 40 parts of potassium chloride, 26 parts of sodium chloride, 20 parts of lithium chloride, 3 parts of zinc chloride, 5 parts of zinc fluoride, 2 parts of sodium fluoride, and 2 parts of lithium fluoride.

[0098] The rest is the same as in Example 1.

[0099] Comparative Example 2

[0100] A high-corrosion-resistant and high-strength solder includes a solder and a flux. The solder includes the following raw materials by weight parts: 50 parts of aluminum, 14 parts of aluminum-silicon alloy, 30 parts of copper, 3 parts of germanium, 0.8 part of manganese, 0.4 part of titanium, 3 parts of tin, 0.15 part of lanthanum, and 0.15 part of cerium.

[0101] The soldering flux comprises the following raw materials by weight parts: 40 parts of potassium chloride, 26 parts of sodium chloride, 20 parts of lithium chloride, 7 parts of potassium fluoride, 7 parts of aluminum fluoride, 3 parts of zinc chloride, 5 parts of zinc fluoride, 2 parts of sodium fluoride, 2 parts of lithium fluoride, 1 part of potassium hexafluorosilicate, and 0.8 part of potassium hydrogen fluoride.

[0102] The rest is the same as in Example 1.

[0103] Performance detection

[0104] The solder of Examples 1-4 and Comparative Examples 1 and 2 was used to weld aluminum alloy pipes. According to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", the corrosion resistance of the welded joints was detected, specifically the neutral salt spray test with a test period of 96 h; according to GB / T228.1-2010 and GB / T 11363-2008, the tensile strength and shear strength of the welded joints were detected. The results are shown in Table 1.

[0105] Table 1. Welding performance test results

[0106]

[0107] As can be seen from Table 1, the solder of Examples 1-4 of the present invention has better corrosion resistance and the mechanical properties of the welded joints are better than those of Comparative Examples 1 and 2.

[0108] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0109] Although the embodiments of the present application have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present application. The scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A high corrosion resistance and high strength solder, characterized in that: The brazing material comprises a brazing material and a brazing agent, wherein the brazing material comprises the following raw materials by weight: 40-55 parts of aluminum, 12-16 parts of aluminum silicon alloy, 27-33 parts of copper, 0.5-5 parts of germanium, 0.6-1 parts of manganese, 0.2-0.6 parts of titanium, 2-5 parts of tin, and 0.1-0.5 parts of rare earth elements; The brazing flux comprises the following raw materials by weight: 25-50 parts of potassium chloride, 10-35 parts of sodium chloride, 4.0-30.0 parts of lithium chloride, 10-20 parts of potassium fluoride-aluminum fluoride complex, 0.5-6 parts of zinc chloride, 2-6 parts of zinc fluoride, 0.05-3 parts of sodium fluoride, 0.05-3 parts of lithium fluoride, 0.05-2 parts of potassium hexafluorosilicate, and 0.05-1.5 parts of potassium hydrogen fluoride; The potassium fluoride-aluminum fluoride composite comprises the following raw materials by weight: 35-45 parts of potassium fluoride, 35-45 parts of aluminum fluoride, 5-8 parts of dopant, and 10-15 parts of coating material; The dopant is one or more of magnesium fluoride, cerium trifluoride, and lanthanum fluoride; The coating material is one or more of aluminum fluoride, lithium fluoride, and magnesium fluoride; The preparation method of the potassium fluoride-aluminum fluoride complex is as follows: S1, dry-milling potassium fluoride and aluminum fluoride, with a ball-to-material ratio of 10-15:1, a ball-milling time of 1-2 hours, and a rotation speed of 300-400 rpm to mix them evenly; S2, adding the dopant to the mixed material in step S1, adding anhydrous ethanol as a dispersant, grinding for 30-60 minutes to make the dopant evenly distributed, the amount of anhydrous ethanol used is 10%-20% of the total mass of the dopant and the mixed material in step S1; S3, sintering the mixture ground in step S2 at a temperature of 600-800° C., keeping the temperature for 2-3 hours under an argon protective atmosphere, and then naturally cooling to room temperature, taking out the sintered material, washing it with deionized water to remove surface impurities, and then drying it at a temperature of 70-90° C. for 10-14 hours to obtain a composite 1; S4, adding the coating material to deionized water, stirring evenly to form a suspension, mixing the composite 1 with the suspension to obtain a slurry with a solid content of 20-40%, atomizing the slurry, and then drying it with hot air, the hot air inlet temperature is 150-250° C., the air outlet temperature is 100-150° C., and the deionized water is evaporated to obtain dry coated composite particles; S5, subjecting the dried coated composite particles to high temperature treatment in an inert gas atmosphere at a temperature of 300-500° C. for a time of 1.5-3 hours.

2. The high corrosion resistance and high strength solder according to claim 1, characterized in that: The rare earth element is one or both of lanthanum and cerium.

3. The method for preparing the high corrosion resistance and high strength solder according to claim 1 or 2, characterized in that: The following steps are involved: Step 1, melting the brazing material at 700-800° C. for 30-80 minutes; Step 2, casting, cooling, and rolling the smelted solder alloy into a strip, and then processing the strip solder into a U-shaped groove; Step 3, mixing and crushing the flux raw materials by ball milling to obtain flux powder with a particle size of 20-30 μm; Step 4, pouring flux powder into the U-shaped groove of the strip solder, and then closing the U-shaped groove of the strip solder by rolling.

4. The method for preparing the high corrosion resistance and high strength solder according to claim 3, characterized in that: The thickness of the strip solder in step 2 is 0.5-1 mm.

5. The method for preparing the high corrosion resistance and high strength solder according to claim 3, characterized in that: In step 3, the ball-to-material ratio during ball milling is 15-20:1 and the rotation speed is 350-450 r / min.

6. The method for preparing the high corrosion resistance and high strength solder according to claim 3, characterized in that: The high corrosion resistance and high strength solder obtained in step 4 is stretched into a filament with a diameter of 0.3-0.6 mm.

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