A high-temperature cobalt-based water-based paste brazing filler metal, a preparation method and use method thereof

Abstract

This invention discloses a high-temperature cobalt-based water-based paste-like brazing filler metal, which is composed of 84%–92% cobalt-based alloy powder and 8%–16% organic binder by mass fraction. The invention also discloses a method for preparing the filler metal: Step 1, preparing cobalt-based alloy powder by vacuum induction melting combined with gas atomization powder preparation; Step 2, preparing the organic binder by mixing and stirring; Step 3, obtaining the filler metal by mixing the materials. The invention further discloses a method for using the filler metal: applying the filler metal to the surface of the pre-connected component to be welded, placing it in an oven, then vacuum heating, and finally cooling to complete the welding. This invention's high-temperature cobalt-based water-based paste-like brazing filler metal, by adding a small amount of organic binder, produces a high-stability, good leveling, long shelf life, and surface oxidation-resistant filler metal during welding. The preparation and use methods of this high-temperature cobalt-based water-based paste-like brazing filler metal are simple and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy welding technology, and in particular relates to a high-temperature cobalt-based water-based paste brazing filler metal and its preparation and application methods. Background Technology

[0002] Aerospace engines have complex structures and face challenges from environments involving high temperatures, high pressures, vibrations, and corrosion during operation, thus placing high demands on material properties and processing techniques. For precision components and complex thin-walled parts in aerospace applications, vacuum brazing is commonly used for connection. Because vacuum brazing uses overall heating, it generates less thermal stress during the welding process, overcoming the uneven thermal shrinkage problems caused by localized heating in traditional welding processes. Furthermore, vacuum brazing allows for the precise connection of multiple parts and components within a single furnace.

[0003] Common nickel-based and cobalt-based brazing filler metals for vacuum brazing are typically prepared into powder form using a combination of vacuum induction melting and inert gas atomization, and then mixed with a binder to form a paste for use. Paste-like brazing filler metals are characterized by ease of handling, rapid leveling, and controllable coating amount, making them particularly suitable for brazing complex components in the aerospace field.

[0004] For example, the Chinese invention patent "A method for preparing an aqueous paste for preparing XHBNi-5 nickel-based solder paste" (publication number CN107838578A) prepares nickel-based solder paste at a certain temperature. Although the prepared nickel-based solder paste has good stability, the preparation process is complicated and involves many steps. It requires the addition of ammonia water for pH adjustment, which is not conducive to large-scale industrial production. At the same time, the high organic content in the nickel-based solder paste will result in a small amount of carbon residue after brazing.

[0005] For example, the Chinese invention patent "A brazing filler metal for vacuum brazing of high-nitrogen steel and its preparation method" (publication number CN109128583A) uses a water-based binder composed of zinc phosphate, ammonium chloride, polyethylene glycol, butyl cyanoacrylate and ammonium persulfate to prepare the brazing filler metal with excellent performance. However, the cyano compounds in the raw materials are easy to cause harm to the human body.

[0006] Therefore, there is an urgent need to develop a paste-like brazing filler metal that has excellent performance, is harmless to the human body, and can be mass-produced industrially. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-temperature cobalt-based water-based paste solder. This high-temperature cobalt-based water-based paste solder, by adding a low content of organic binder, achieves high stability, good leveling properties, long shelf life, and is less prone to surface oxidation during soldering. During use, the organic binder in the high-temperature cobalt-based water-based paste solder completely evaporates at the soldering temperature without affecting the soldering effect.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a high-temperature cobalt-based water-based paste-like brazing filler metal, characterized in that it is composed of the following components by mass fraction: 84% to 92% cobalt-based alloy powder, with the balance being an organic binder; the organic binder is composed of the following components by mass fraction: 2% to 5% cellulose-based thickener, 0.2% to 3% polymer-based binder, 0.01% to 0.05% boric acid-based gelling agent, with the balance being deionized water.

[0009] This invention relates to a high-temperature cobalt-based water-based paste-like brazing filler metal, which is prepared by adding an organic binder to a high-temperature cobalt-based water-based paste-like brazing filler metal and mixing it uniformly with cobalt-based alloy powder. The organic binder contains a cellulose-based thickener and a polymer-based adhesive, which can effectively improve the stability of the high-temperature cobalt-based water-based paste-like brazing filler metal. Utilizing the high viscosity of the cellulose-based thickener under static and low shear conditions, combined with the bonding effect of the polymer-based adhesive, it helps to prevent the high-temperature cobalt-based water-based paste-like brazing filler metal from delaminating during storage, thus extending its shelf life. It also provides a certain degree of adhesion to the surface to be welded, preventing displacement of the weld surface before furnace loading and thus preventing the scrapping of the welded assembly. At the same time, the low viscosity of the cellulose-based thickener under high shear conditions also makes the high-temperature cobalt-based water-based paste-like brazing filler metal easier to extrude and spread evenly during use.

[0010] This invention prevents oxidation of the surface of the high-temperature cobalt-based water-based paste solder during welding by adding boric acid gelling agents to the solder, thus significantly reducing the amount of oxidation residue that appears after welding.

[0011] The above-mentioned high-temperature cobalt-based water-based paste solder is characterized in that the mass fraction of each element in the cobalt-based alloy powder is: Cr 18%~26%, Ni 16%~21%, Si 0%~9%, W 3.5%~11%, B 0.6%~3.5%, C 0.2%~0.8%, with the balance being Co.

[0012] The above-mentioned high-temperature cobalt-based water-based paste solder is characterized in that the particle size of the cobalt-based alloy powder is 20μm to 100μm.

[0013] The present invention sets the alloy powder within a certain particle size range to have a certain fluidity, which is conducive to mixing with the binder to form a paste with uniform dispersion and good stability.

[0014] The above-mentioned high-temperature cobalt-based aqueous paste solder is characterized in that the cellulose thickener is one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose.

[0015] The above-mentioned high-temperature cobalt-based water-based paste solder is characterized in that the polymer binder is one or more of polyacrylic acid, sodium polyacrylate, polyacrylamide, polyethylene glycol, and polyvinyl alcohol.

[0016] The above-mentioned high-temperature cobalt-based aqueous paste-like brazing filler metal is characterized in that the boric acid gelling agent is one or more of trimethyl borate, triethanolamine borate, and boric acid.

[0017] Meanwhile, the present invention also discloses a method for preparing the above-mentioned high-temperature cobalt-based aqueous paste solder, characterized in that the method includes the following steps:

[0018] Step 1: Preparation of cobalt-based alloy powder: After mixing the cobalt-based alloy powder raw materials, the powder is prepared by vacuum induction melting combined with gas atomization powder preparation method, and then sieved to obtain cobalt-based alloy powder with a particle size of 20μm to 100μm.

[0019] Step 2, Preparation of organic binder: Mix cellulose thickener, polymer binder, boric acid gelling agent and deionized water, let stand for 24h to 48h until the cellulose thickener and polymer binder are completely dissolved, and then use mechanical stirring for 1h to 5h to obtain a viscous transparent sol, i.e. organic binder.

[0020] Step 3: Preparation of high-temperature cobalt-based water-based paste brazing filler metal: The cobalt-based alloy powder obtained in Step 1 is mixed with the organic binder obtained in Step 2, and then finely ground and mixed in a three-roll mill to obtain high-temperature cobalt-based water-based paste brazing filler metal.

[0021] Furthermore, the present invention also discloses a method for using the above-mentioned high-temperature cobalt-based aqueous paste solder, characterized in that the method includes the following steps:

[0022] Step 1: Grind the two surfaces to be welded of the pre-connected component with sandpaper of 300 grit, 500 grit, 800 grit and 1000 grit in sequence. After grinding, immerse the surfaces to be welded in a container of acetone and put them in an ultrasonic cleaner for 5 to 10 minutes. Then take them out and place them at room temperature.

[0023] Step 2: Apply high-temperature cobalt-based water-based solder paste evenly to one of the surfaces to be soldered, which was placed at room temperature in Step 1. Then, put the two surfaces to be soldered together, ensuring that the high-temperature cobalt-based water-based solder paste fills the space between the two surfaces. Place the pre-connected assembly into an oven and treat it at 60°C for 0.5 to 2 hours.

[0024] Step 3: Transfer the pre-connected components processed in the oven in Step 2 into the vacuum brazing furnace, turn on the vacuum pump unit, and evacuate until the vacuum level inside the furnace reaches 2.5 × 10⁻⁶. -3 Pa, then raise the temperature to 500℃ at a rate of 2℃ / min to 3℃ / min and hold for 10 min, then raise the temperature to 1000℃ at a rate of 5℃ / min and hold for 10 min, then continue to raise the temperature to 1150℃ to 1200℃ at a rate of 5℃ / min to 10℃ / min and hold for 10 min to 20 min before starting to cool down until the temperature inside the vacuum brazing furnace drops to 400℃ to 500℃;

[0025] Step 4: Turn on the argon purging switch until the vacuum level inside the vacuum brazing furnace is restored to 1×10⁻⁶. 5 After the furnace temperature drops to room temperature, the pre-welded components are removed from the furnace.

[0026] In step three of the method of this invention, a slower heating rate is used during the heating process to 500℃, which is beneficial for the thermal decomposition and volatilization of organic matter in the high-temperature cobalt-based water-based solder paste, preventing carbonization of organic matter caused by excessively rapid heating, and thus improving the weld quality. When the temperature reaches 1000℃, which is close to the melting temperature of the high-temperature cobalt-based water-based solder paste, holding the temperature for 10 minutes ensures that the temperatures of the two surfaces to be welded and all parts of the high-temperature cobalt-based water-based solder paste are consistent. When the temperature reaches 1150-1200℃, the high-temperature cobalt-based water-based solder paste has completely melted, and holding the temperature for 10-20 minutes facilitates elemental diffusion between the high-temperature cobalt-based water-based solder paste and the surfaces to be welded, resulting in a more reliable bond between the two surfaces.

[0027] The above-mentioned method for using a high-temperature cobalt-based water-based paste solder is characterized in that the pre-connection component in step one is made of a nickel-based high-temperature alloy or a cobalt-based high-temperature alloy.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1. The high-temperature cobalt-based water-based paste brazing filler metal of the present invention is composed of cobalt-based alloy powder and organic binder. By controlling the composition and mass ratio of the organic binder, a high-temperature cobalt-based water-based paste brazing filler metal with high stability, good leveling properties, long shelf life and low surface oxidation during the welding process is obtained. The organic binder has a low organic content, and the organic matter in the high-temperature cobalt-based water-based paste brazing filler metal can be completely volatilized at the brazing temperature during use, without affecting the brazing effect and ensuring the welding quality.

[0030] 2. The preparation method of the high-temperature cobalt-based water-based paste solder of the present invention is simple and can be prepared at room temperature without controlling the ambient temperature and pH value. Moreover, the ingredients are safe and non-toxic, and no irritating odor will be produced during the application process, which will not harm human health. It is suitable for industrial production.

[0031] 3. The solvent of the high-temperature cobalt-based water-based paste brazing filler metal of the present invention is water, which can be completely evaporated by low-temperature treatment in an oven before loading into the furnace. This operation will not affect the welding performance of the high-temperature cobalt-based water-based paste brazing filler metal.

[0032] 4. The high-temperature cobalt-based water-based paste brazing filler metal of the present invention has a certain degree of adhesion to the metal surface, which can prevent the two bonding surfaces to be welded from shifting before loading into the furnace, thus preventing the pre-connected components from being scrapped.

[0033] 5. When using the high-temperature cobalt-based water-based paste brazing filler metal of the present invention, a slower heating rate is adopted during the process of heating to 500°C in the vacuum brazing furnace. This is beneficial for the thermal decomposition and volatilization of organic matter in the high-temperature cobalt-based water-based paste brazing filler metal, preventing the organic matter from carbonizing due to excessively rapid heating, and thus improving the quality of the weld.

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0035] Figure 1 This is a physical image of the high-temperature cobalt-based aqueous paste solder prepared in Example 1 of the present invention. Detailed Implementation

[0036] Example 1

[0037] In this embodiment, the high-temperature cobalt-based water-based paste solder is composed of 92% cobalt-based alloy powder and 8% organic binder by mass. The organic binder is composed of the following components by mass: 1% hydroxypropyl methylcellulose, 0.2% polyacrylic acid, 2% polyacrylamide, 0.01% boric acid, and the balance being deionized water.

[0038] The mass fractions of each element in the cobalt-based alloy powder are: Cr 18%, Ni 16%, Si 0%, W 3.5%, B 0.6%, C 0.2%, with the balance being Co.

[0039] The preparation of the high-temperature cobalt-based aqueous paste solder in this embodiment includes the following steps:

[0040] Step 1: Preparation of cobalt-based alloy powder: The raw materials for cobalt-based alloy powder are prepared and mixed. The powder is then sprayed using a vacuum induction melting method combined with gas atomization powdering. After sieving, cobalt-based alloy powder with a particle size of 20μm to 45μm is obtained.

[0041] Step 2, Preparation of organic binder: Weigh and mix the organic binder: hydroxypropyl methylcellulose, polyacrylic acid, polyacrylamide, boric acid and deionized water, let stand for 24 hours until hydroxypropyl methylcellulose, polyacrylic acid and polyacrylamide are completely dissolved by water absorption, and then use mechanical stirring for 1 hour to obtain a viscous and transparent sol-like organic binder.

[0042] Step 3: Preparation of high-temperature cobalt-based water-based paste brazing filler metal: The cobalt-based alloy powder obtained in Step 1 and the organic binder obtained in Step 2 are mixed at a mass ratio of 92:8. The mixture is then finely ground and mixed using a three-roll mill to obtain the high-temperature cobalt-based water-based paste brazing filler metal.

[0043] In step one of this embodiment, hydroxypropyl methylcellulose can be replaced with one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methylcellulose, in addition to hydroxypropyl methylcellulose. Polyacrylic acid and polyacrylamide can be replaced with one or more of polyacrylic acid, sodium polyacrylate, polyacrylamide, polyethylene glycol, and polyvinyl alcohol, in addition to polypropylene and polyacrylamide. Boric acid can be replaced with one or more of trimethyl borate, triethanolamine borate, and boric acid, in addition to boric acid.

[0044] Figure 1 The image shows the actual product of the high-temperature cobalt-based aqueous paste solder prepared in this embodiment. The high-temperature cobalt-based aqueous paste solder has good fluidity, as tested.

[0045] The method of using the high-temperature cobalt-based aqueous paste solder prepared in this embodiment includes the following steps:

[0046] Step 1: Grind the surfaces of the pre-connected components to be welded with 300 grit, 500 grit, 800 grit, and 1000 grit sandpaper in sequence. After grinding, immerse the surfaces to be welded in a container of acetone and put them in an ultrasonic cleaner for 5 minutes. Then take them out and place them at room temperature.

[0047] Step 2: Apply high-temperature cobalt-based water-based solder paste evenly to one of the surfaces to be soldered, and then place the two surfaces to be soldered together, ensuring that the solder paste fills the space between the two surfaces. Place the assembled components to be soldered in an oven and treat them at 60°C for 0.5 hours.

[0048] Step 3: Transfer the pre-connected components after processing into the vacuum brazing furnace, turn on the vacuum pump unit, and evacuate until the vacuum level inside the furnace reaches 2.5 × 10⁻⁶. -3 Pa, then raise the temperature to 500℃ at a rate of 2℃ / min and hold for 10min, then raise the temperature to 1000℃ at a rate of 5℃ / min and hold for 10min, then continue to raise the temperature to 1150℃ at a rate of 5℃ / min and hold for 20min before starting to cool down until the temperature inside the brazing furnace drops to 400℃.

[0049] Step 4: After the temperature inside the brazing furnace drops to 400℃, turn on the argon purging switch until the vacuum level inside the furnace returns to 1×10⁻⁶. 5 Pa, continue to wait for the furnace temperature to drop to room temperature, then open the furnace and take out the welded pre-connected components.

[0050] Example 2

[0051] In this embodiment, the high-temperature cobalt-based aqueous paste solder is composed of 84% cobalt-based alloy powder and 16% organic binder by mass. The organic binder is composed of the following components by mass: 5% hydroxyethyl cellulose, 3% polyvinyl alcohol, 0.05% trimethyl borate, and the balance being deionized water.

[0052] The mass fractions of each element in the cobalt-based alloy powder are: Cr 26%, Ni 21%, Si 9%, W 11%, B 3.5%, C 0.8%, with the balance being Co.

[0053] The preparation of the high-temperature cobalt-based aqueous paste solder in this embodiment includes the following steps:

[0054] Step 1: Preparation of cobalt-based alloy powder: The raw materials for cobalt-based alloy powder are prepared, mixed, and then sprayed using a vacuum induction melting combined with gas atomization powdering method. After sieving, cobalt-based alloy powder with a particle size of 75μm to 100μm is obtained.

[0055] Step 2, Preparation of organic binder: Weigh and mix the organic binder: hydroxyethyl cellulose, polyvinyl alcohol, trimethyl borate and deionized water, let stand for 48 hours, and wait for the hydroxyethyl cellulose and polyvinyl alcohol to completely absorb water and dissolve. Then, use mechanical stirring for 5 hours to obtain a viscous and transparent sol-like organic binder.

[0056] Step 3: Preparation of high-temperature cobalt-based water-based paste brazing filler metal: The cobalt-based alloy powder obtained in Step 1 and the organic binder obtained in Step 2 are mixed at a weight ratio of 84:16, and the mixture is finely ground and mixed using a three-roll mill to obtain high-temperature cobalt-based water-based paste brazing filler metal.

[0057] In step one of this embodiment, hydroxyethyl cellulose can be replaced with one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, and hydroxypropyl methyl cellulose, in addition to hydroxyethyl cellulose. Polyvinyl alcohol can be replaced with one or more of polyacrylic acid, polyacrylamide, sodium polyacrylate, and polyethylene glycol, in addition to polyvinyl alcohol. Trimethyl borate can be replaced with one or more of boric acid and triethanolamine borate, in addition to trimethyl borate.

[0058] The method of using the high-temperature cobalt-based aqueous paste solder prepared in this embodiment includes the following steps:

[0059] Step 1: Grind the surfaces of the pre-connected components to be welded with sandpaper of 300 grit, 500 grit, 800 grit and 1000 grit in sequence. After grinding, immerse the surfaces to be welded in a container of acetone and put them in an ultrasonic cleaner for 10 minutes. Then take them out and place them at room temperature.

[0060] Step 2: Apply high-temperature cobalt-based water-based solder paste evenly to one of the surfaces to be soldered, and then place the two surfaces to be soldered together, ensuring that the solder paste fills the space between the two surfaces. Place the assembled components to be soldered in an oven and treat them at 60°C for 2 hours.

[0061] Step 3: Transfer the pre-connected components after processing into the vacuum brazing furnace, turn on the vacuum pump unit, and evacuate the furnace until the vacuum level reaches 2.5 × 10⁻⁶. -3 Pa, then raise the temperature to 500℃ at a rate of 3℃ / min and hold for 10min, then raise the temperature to 1000℃ at a rate of 5℃ / min and hold for 10min, then raise the temperature to 1200℃ at a rate of 10℃ / min and hold for 10min, then begin to cool down until the temperature inside the brazing furnace drops to 500℃.

[0062] Step 4: After the temperature inside the brazing furnace drops to 500℃, turn on the argon purging switch until the vacuum level inside the furnace returns to 1×10⁻⁶. 5 Pa, continue to wait for the furnace temperature to drop to room temperature, then open the furnace and take out the welded pre-connected components.

[0063] Example 3

[0064] In this embodiment, the high-temperature cobalt-based aqueous paste solder is composed of 90% cobalt-based alloy powder and 10% organic binder by mass. The organic binder is composed of the following components by mass: 3% hydroxypropyl methylcellulose, 1% polyacrylic acid, 0.5% polyacrylamide, 0.03% triethanolamine borate, and the balance being deionized water.

[0065] The mass fraction of each element in the cobalt-based alloy powder is: Cr 20%, Ni 19%, Si 6%, W 5%, B 2%, C 0.4%, with the balance being Co.

[0066] The preparation of the high-temperature cobalt-based aqueous paste solder in this embodiment includes the following steps:

[0067] Step 1: Preparation of cobalt-based alloy powder: The raw materials for cobalt-based alloy powder are prepared and mixed. The powder is then sprayed using a vacuum induction melting method combined with gas atomization powdering. After sieving, cobalt-based alloy powder with a particle size of 45μm to 65μm is obtained.

[0068] Step 2, Preparation of organic binder: Weigh and mix the organic binder: hydroxypropyl methylcellulose, polyacrylic acid, polyacrylamide, triethanolamine borate and deionized water, let stand for 30 hours, and wait for the hydroxypropyl methylcellulose, polyacrylic acid and polyacrylamide to completely absorb water and dissolve. Then, use mechanical stirring for 3 hours to obtain a viscous and transparent sol-like organic binder.

[0069] Step 3: Preparation of high-temperature cobalt-based water-based paste brazing filler metal: The cobalt-based alloy powder obtained in Step 1 and the organic binder obtained in Step 2 are mixed at a weight ratio of 90:10. The mixture is then finely ground and mixed using a three-roll mill to obtain the high-temperature cobalt-based water-based paste brazing filler metal.

[0070] In step one of this embodiment, hydroxypropyl methylcellulose can be replaced with one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, and hydroxyethyl cellulose, in addition to hydroxypropyl methylcellulose. Polyacrylic acid and polyacrylamide can be replaced with one or more of sodium polyacrylate, polyethylene glycol, and polyvinyl alcohol, in addition to polyacrylic acid and polyacrylamide. Triethanolamine borate can be replaced with one or more of trimethyl borate and boric acid, in addition to triethanolamine borate.

[0071] The method of using the high-temperature cobalt-based aqueous paste solder prepared in this embodiment includes the following steps:

[0072] Step 1: Grind the surfaces of the pre-connected components to be welded with 300 grit, 500 grit, 800 grit and 1000 grit sandpaper in sequence. After grinding, immerse the surfaces to be welded in a container of acetone and put them in an ultrasonic cleaner for 7 minutes. Then take them out and place them at room temperature.

[0073] Step 2: Apply high-temperature cobalt-based water-based solder paste evenly to one of the surfaces to be soldered, and then place the two surfaces to be soldered together. During the process, ensure that the solder paste fills the space between the two surfaces. Place the assembled components to be soldered in an oven and treat them at 60°C for 1 hour.

[0074] Step 3: Transfer the pre-connected components after processing into the vacuum brazing furnace, turn on the vacuum pump unit, and evacuate the furnace until the vacuum level reaches 2.5 × 10⁻⁶. -3 Pa, then raise the temperature to 500℃ at a rate of 2℃ / min and hold for 10min, then raise the temperature to 1000℃ at a rate of 5℃ / min and hold for 10min, then raise the temperature to 1170℃ at a rate of 7℃ / min and hold for 15min before cooling down until the temperature inside the brazing furnace drops to 450℃.

[0075] Step 4: After the temperature inside the brazing furnace drops to 450℃, turn on the argon purging switch until the vacuum level inside the furnace returns to 1×10⁻⁶. 5 Pa, continue to wait for the furnace temperature to drop to room temperature, then open the furnace and take out the welded pre-connected components.

[0076] Example 4

[0077] In this embodiment, the high-temperature cobalt-based aqueous paste solder is composed of 88% cobalt-based alloy powder and 12% organic binder by mass. The organic binder is composed of the following components by mass: 1% carboxymethyl cellulose, 2.8% sodium carboxymethyl cellulose, 0.2% polyacrylic acid, 0.04% trimethyl borate, and the balance being deionized water.

[0078] The mass fractions of each element in the cobalt-based alloy powder are: Cr 23%, Ni 20%, Si 4%, W 4%, B 3%, C 0.4%, with the balance being Co.

[0079] The preparation of the high-temperature cobalt-based aqueous paste solder in this embodiment includes the following steps:

[0080] Step 1: Preparation of cobalt-based alloy powder: The raw materials for cobalt-based alloy powder are prepared, mixed, and then sprayed using a vacuum induction melting combined with gas atomization powdering method. After sieving, cobalt-based alloy powder with a particle size of 50μm to 74μm is obtained.

[0081] Step 2, Preparation of organic binder: Weigh and mix the organic binder: carboxymethyl cellulose, sodium carboxymethyl cellulose, polyvinyl alcohol, polyacrylic acid, trimethyl borate and deionized water, let stand for 36 hours, and wait for hydroxypropyl methyl cellulose, polyacrylic acid and polyacrylamide to completely absorb water and dissolve. Then, use mechanical stirring for 4 hours to obtain a viscous and transparent sol-like organic binder.

[0082] Step 3: Preparation of high-temperature cobalt-based water-based paste brazing filler metal: The cobalt-based alloy powder obtained in Step 1 and the organic binder obtained in Step 2 are mixed at a weight ratio of 88:12. The mixture is then finely ground and mixed using a three-roll mill to obtain the high-temperature cobalt-based water-based paste brazing filler metal.

[0083] In step one of this embodiment, carboxymethyl cellulose and sodium carboxymethyl cellulose can be replaced with one or more of hydroxypropyl methyl cellulose and hydroxyethyl cellulose, in addition to carboxymethyl cellulose and sodium carboxymethyl cellulose. Polyvinyl alcohol and polyacrylic acid can be replaced with one or more of sodium polyacrylate, polyacrylamide and polyethylene glycol, in addition to polyvinyl alcohol and polyacrylic acid. Trimethyl borate can be replaced with one or more of boric acid and triethanolamine borate, in addition to trimethyl borate.

[0084] The method of using the high-temperature cobalt-based aqueous paste solder prepared in this embodiment includes the following steps:

[0085] Step 1: Grind the surfaces of the pre-connected components to be welded with 300 grit, 500 grit, 800 grit and 1000 grit sandpaper in sequence. After grinding, immerse the surfaces to be welded in a container of acetone and put them in an ultrasonic cleaner for 9 minutes. Then take them out and place them at room temperature.

[0086] Step 2: Apply high-temperature cobalt-based water-based solder paste evenly to one of the surfaces to be soldered, and then place the two surfaces to be soldered together, ensuring that the solder paste fills the space between the two surfaces. Place the assembled components to be soldered in an oven and treat them at 60°C for 1.5 hours.

[0087] Step 3: Transfer the pre-connected components after processing into the vacuum brazing furnace, turn on the vacuum pump unit, and evacuate the furnace until the vacuum level reaches 2.5 × 10⁻⁶. -3 Pa, then raise the temperature to 500℃ at a rate of 2℃ / min and hold for 10min, then raise the temperature to 1000℃ at a rate of 5℃ / min and hold for 10min, then continue to raise the temperature to 1190℃ at a rate of 6℃ / min and hold for 16min before starting to cool down until the temperature inside the brazing furnace drops to 460℃.

[0088] Step 4: Once the temperature inside the brazing furnace drops to 460℃, turn on the argon purging switch until the vacuum level inside the furnace returns to 1×10⁻⁶. 5 Pa, continue to wait for the furnace temperature to drop to room temperature, then open the furnace and take out the welded pre-connected components.

[0089] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A high-temperature cobalt-based water-based paste-like solder, characterized in that, It is composed of the following components by mass fraction: 84%~92% cobalt-based alloy powder, with the balance being organic binder; the organic binder is composed of the following components by mass fraction: 1%~5% cellulose-based thickener, 0.2%~3% polymer-based binder, 0.01%~0.05% boric acid-based gelling agent, with the balance being deionized water; the cellulose-based thickener is one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose; the polymer-based binder is one or more of polyacrylic acid, sodium polyacrylate, polyacrylamide, polyacrylamide, polyethylene glycol, and polyvinyl alcohol; the boric acid-based gelling agent is one or more of trimethyl borate, triethanolamine borate, and boric acid.

2. The high-temperature cobalt-based aqueous paste solder according to claim 1, characterized in that, The mass fractions of each element in the cobalt-based alloy powder are: Cr 18%~26%, Ni 16%~21%, Si 0%~9%, W 3.5%~11%, B 0.6%~3.5%, C 0.2%~0.8%, with the balance being Co.

3. The high-temperature cobalt-based aqueous paste solder according to claim 1, characterized in that, The cobalt-based alloy powder has a particle size of 20μm to 100μm.

4. A method for preparing a high-temperature cobalt-based aqueous paste solder as described in any one of claims 1 to 3, characterized in that, The method includes the following steps: Step 1: Preparation of cobalt-based alloy powder: After mixing the cobalt-based alloy powder raw materials, the powder is prepared by vacuum induction melting combined with gas atomization powder preparation method, and then sieved to obtain cobalt-based alloy powder with a particle size of 20μm~100μm. Step 2, Preparation of organic binder: Mix cellulose thickener, polymer binder, boric acid gelling agent and deionized water, let stand for 24h~48h until the cellulose thickener and polymer binder are completely dissolved, and then use mechanical stirring for 1h~5h to obtain a viscous transparent sol, i.e. organic binder. Step 3: Preparation of high-temperature cobalt-based water-based paste brazing filler metal: The cobalt-based alloy powder obtained in Step 1 is mixed with the organic binder obtained in Step 2, and then finely ground and mixed in a three-roll mill to obtain high-temperature cobalt-based water-based paste brazing filler metal.

5. A method of using the high-temperature cobalt-based aqueous paste solder as described in any one of claims 1 to 3, characterized in that, The method includes the following steps: Step 1: Grind the two surfaces to be welded of the pre-connected component with sandpaper of 300 grit, 500 grit, 800 grit and 1000 grit in sequence. After grinding, immerse the surfaces to be welded in a container of acetone and put them in an ultrasonic cleaner for 5 to 10 minutes. Then take them out and place them at room temperature. Step 2: Apply high-temperature cobalt-based water-based solder paste evenly to one of the surfaces to be soldered, which was placed at room temperature in Step 1. Then, put the two surfaces to be soldered together, ensuring that the high-temperature cobalt-based water-based solder paste fills the space between the two surfaces. Place the pre-connected assembly into an oven and treat it at 60°C for 0.5 to 2 hours. Step 3: Transfer the pre-connected components processed in Step 2 into the vacuum brazing furnace, turn on the vacuum pump unit, and evacuate until the vacuum level inside the furnace reaches 2.5 × 10⁻⁶. -3 Pa, then raise the temperature to 500℃ at a rate of 2℃ / min~3℃ / min and hold for 10min, then raise the temperature to 1000℃ at a rate of 5℃ / min and hold for 10min, then continue to raise the temperature to 1150℃~1200℃ at a rate of 5℃ / min~10℃ / min and hold for 10min~20min before starting to cool down until the temperature inside the vacuum brazing furnace drops to 400℃~500℃; Step 4: Turn on the argon purging switch until the vacuum level inside the vacuum brazing furnace is restored to 1×10⁻⁶. 5 After the furnace temperature drops to room temperature, the pre-welded components are removed from the furnace.

6. The method of using a high-temperature cobalt-based aqueous paste solder according to claim 5, characterized in that, The pre-connected components mentioned in step one are made of nickel-based high-temperature alloys or cobalt-based high-temperature alloys.

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