Porous filler metal film for brazing hard metal and stainless steel and method of making same

Abstract

The application discloses a preparation method of a porous filler metal film for brazing hard alloy and stainless steel, and comprises the following steps: (1) taking raw materials to obtain a mixed slurry by taking a binder, a surfactant, a plasticizer and a solvent according to a mass ratio of 1:0.8:0.8:6-15, and adding 5-10 wt.% of a pore-forming agent into metal powder to obtain a mixed powder; and (2) placing a stainless steel plate in a nitrogen atmosphere to dry for 2-3 hours and then taking the film. The porous filler metal film prepared by the application is a filler metal for brazing hard alloy and stainless steel, which is based on a nickel-copper active filler metal, and is modified by adding manganese and cobalt elements, wherein nickel is a strengthening element, can realize solid solution strengthening with copper elements, improves the wear resistance of the alloy filler metal, nickel and manganese elements can improve the strength of the joint, and zinc elements can reduce the welding temperature and improve the wettability of the filler metal.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more specifically to porous brazing filler films for brazing cemented carbide and stainless steel, and methods for preparing the same. Background Technology

[0002] Hard alloys possess excellent properties such as high hardness, wear resistance, heat resistance, corrosion resistance, and good red hardness, making them widely used in industrial fields such as machining, geological exploration, and mining. However, their poor toughness and machinability limit their application range. Welding hard alloys to steel can effectively address the shortcomings of hard alloys, such as limited size, simple shapes, high cost, and poor toughness, thus expanding their application range and possessing significant practical value. Complex components formed from this method are widely used in engineering projects such as oil drilling, mining, and space exploration. Connecting hard alloys and stainless steel using brazing methods offers advantages such as stable metallurgical bonding and high mechanical properties, demonstrating promising research and application prospects.

[0003] Currently, most cemented carbide is embedded in medium carbon steel or stainless steel substrates using brazing methods. The quality of brazing directly affects the performance of the cemented carbide. Due to the significant difference in thermal expansion coefficients between cemented carbide and steel, welding issues have hindered the wider application of cemented carbide. This invention aims to research a porous brazing filler metal film with low melting temperature and excellent wetting properties. This invention provides a porous brazing filler metal film for brazing cemented carbide and stainless steel, and its preparation method. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the purpose of this invention is to provide a porous brazing filler metal film for brazing cemented carbide and stainless steel and a method for preparing the same, so as to solve the problems mentioned in the background art.

[0005] The technical problem solved by the present invention is addressed by the following technical solution: The present invention provides a method for preparing a porous brazing filler metal film for brazing cemented carbide and stainless steel, comprising the following steps;

[0006] (1) Weigh the raw materials

[0007] A mixed slurry is obtained by weighing the binder, surfactant, plasticizer and solvent in a mass ratio of 1:0.8:0.8:6 to 15, and 5 to 10 wt.% of a pore-forming agent is added to the metal powder to obtain a mixed powder.

[0008] (2) Casting molding

[0009] The mixed slurry and mixed powder are placed in a sealed container at a mass ratio of 1:2-5 and mixed in a powder mixer for 10-24 hours to obtain a uniform slurry. The slurry is then uniformly coated onto a stainless steel plate using a coating tool to a thickness of 100-1000 μm. The stainless steel plate is dried in a nitrogen atmosphere for 2-3 hours before the film is removed.

[0010] (3) Sintering and shaping

[0011] The membrane is sintered in a vacuum sintering furnace and then ultrasonically cleaned to obtain a solder film with a certain toughness, which is then cut and rolled as needed.

[0012] Preferably, the metal powder in step (1) is composed of the following components by weight percentage: 50% to 60% Cu, 10% to 20% Ni, 0% to 4% Mn, 0% to 10% Co, and the balance Zn. All powders are spherical powders with a particle size of 1 to 100 micrometers and a purity of more than 99.8%.

[0013] Preferably, the pore-forming agent in step (1) is one or more of carbon particles, polystyrene microspheres, polymethyl methacrylate microspheres, inorganic ammonium salts, and potassium sulfate.

[0014] Preferably, the binder is PVB, the surfactant is Tween-20, the plasticizer is PEG or glycerol, and the solvent is alcohol.

[0015] Preferably, the brazing heating method used includes, but is not limited to, induction brazing, vacuum brazing, resistance brazing, and furnace brazing.

[0016] Preferably, the specific steps of the sintering process are as follows:

[0017] The vacuum molybdenum sheet sintering furnace is heated to 200℃~300℃ at a heating rate of 1℃ / min~10℃ / min and held for 60~360min.

[0018] Then raise the temperature to 350℃~400℃ at a heating rate of 1℃ / min~10℃ / min and hold for 60~360min;

[0019] Then, increase the temperature to 450℃~500℃ at a heating rate of 1℃ / min~10℃ / min and hold for 60~360min; then, increase the temperature to 600℃~800℃ at a heating rate of 1℃ / min~10℃ / min and hold for 60~120min.

[0020] Then, increase the temperature to 800℃~950℃ at a heating rate of 1℃ / min~10℃ / min and hold for 60~240min. After holding, decrease the temperature to 500℃~600℃ at a cooling rate of 1℃ / min~5℃ / min and hold for 60~360min. After holding, cool the furnace to room temperature.

[0021] A porous brazing filler film prepared by a method for brazing cemented carbide and stainless steel.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention prepares a porous brazing filler metal film for brazing cemented carbide and stainless steel. Based on a nickel-copper active brazing filler metal, it modifies the alloy filler metal by adding manganese and cobalt. Nickel acts as a strengthening element, achieving solid solution strengthening with copper to improve the wear resistance of the alloy filler metal. Nickel and manganese enhance joint strength, while zinc lowers welding temperature and improves wettability. The prepared brazing filler metal film is soft and tough, with a smooth surface and a thickness controllable between 100 and 600 micrometers. It can be rolled for storage and die-cut into any shape. It adapts well to different brazed joint shapes, and the thickness during use can be controlled by scraping or rolling, facilitating dosage control. This filler metal features good wettability, a low melting point, a brazing temperature range of 850–950°C, a narrow solid-liquid temperature range, no residue after melting, and good shear resistance and wear resistance at the joint. This invention employs a mechanical mixing and metallurgical alloying method to prepare porous alloy brazing films. The preparation process is simple, facilitating mass production, and offers advantages such as low energy consumption, simple operation, high production efficiency, and easy control of alloy composition and dosage. The porous brazing film of this invention exhibits excellent results when applied to brazing composite materials made of YG8 cemented carbide and 316 stainless steel, achieving a joint shear strength of 423.26–546.58 MPa. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. 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.

[0025] The method for preparing a porous brazing filler metal film for brazing cemented carbide and stainless steel in this embodiment includes the following steps;

[0026] (1) Weigh the raw materials

[0027] A mixed slurry is obtained by weighing the binder, surfactant, plasticizer and solvent in a mass ratio of 1:0.8:0.8:6 to 15, and 5 to 10 wt.% of a pore-forming agent is added to the metal powder to obtain a mixed powder.

[0028] (2) Casting molding

[0029] The mixed slurry and mixed powder are placed in a sealed container at a mass ratio of 1:2-5 and mixed in a powder mixer for 10-24 hours to obtain a uniform slurry. The slurry is then uniformly coated onto a stainless steel plate using a coating tool to a thickness of 100-1000 μm. The stainless steel plate is dried in a nitrogen atmosphere for 2-3 hours before the film is removed.

[0030] (3) Sintering and shaping

[0031] The membrane is sintered in a vacuum sintering furnace and then ultrasonically cleaned to obtain a solder film with a certain toughness, which is then cut and rolled as needed.

[0032] In step (1) of this embodiment, the metal powder is composed of the following components by weight percentage: 50% to 60% Cu, 10% to 20% Ni, 0% to 4% Mn, 0% to 10% Co, and the balance Zn. All powders are spherical powders with a particle size of 1 to 100 micrometers and a purity of more than 99.8%.

[0033] In step (1) of this embodiment, the pore-forming agent is one or more of carbon particles, polystyrene microspheres, polymethyl methacrylate microspheres, inorganic ammonium salts, and potassium sulfate.

[0034] In this embodiment, the binder is PVB, the surfactant is Tween-20, the plasticizer is PEG or glycerol, and the solvent is alcohol.

[0035] The brazing heating methods used in this embodiment include, but are not limited to, induction brazing, vacuum brazing, resistance brazing, and furnace brazing.

[0036] The specific steps of the sintering process in this embodiment are as follows:

[0037] The vacuum molybdenum sheet sintering furnace is heated to 200℃~300℃ at a heating rate of 1℃ / min~10℃ / min and held for 60~360min.

[0038] Then raise the temperature to 350℃~400℃ at a heating rate of 1℃ / min~10℃ / min and hold for 60~360min;

[0039] Then, increase the temperature to 450℃~500℃ at a heating rate of 1℃ / min~10℃ / min and hold for 60~360min; then, increase the temperature to 600℃~800℃ at a heating rate of 1℃ / min~10℃ / min and hold for 60~120min.

[0040] Then, increase the temperature to 800℃~950℃ at a heating rate of 1℃ / min~10℃ / min and hold for 60~240min. After holding, decrease the temperature to 500℃~600℃ at a cooling rate of 1℃ / min~5℃ / min and hold for 60~360min. After holding, cool the furnace to room temperature.

[0041] This embodiment describes a method for preparing a porous brazing filler film for brazing cemented carbide and stainless steel.

[0042] Example 1

[0043] The porous solder film described in this embodiment is prepared according to the following steps:

[0044] 1. Prepare the slurry

[0045] PVB, Tween-20, PEG, and alcohol were weighed in a mass ratio of 1:0.8:0.8:8 to obtain a mixed slurry. 5 wt.% potassium sulfate was added to the metal powder to obtain a mixed powder. The mixed slurry and mixed powder were placed in a sealed container at a mass ratio of 1:4 and mixed in a powder mixer for 10–24 hours to obtain a homogeneous slurry. The metal powder consisted of the following components by weight percentage: 60% Cu, 10% Ni, 3% Mn, 5% Co, and the balance Zn. All powders were spherical with a particle size of 48 micrometers and a purity higher than 99.8%.

[0046] 2. Casting

[0047] The mixture was stirred in a powder mixer for 24 hours to obtain a uniform slurry. The slurry was then evenly coated onto a stainless steel plate using a coating tool to a thickness of 500 μm. The stainless steel plate was dried in a nitrogen atmosphere for 3 hours before the film was removed.

[0048] 3. Sintering and shaping

[0049] The membrane was placed in a vacuum sintering furnace, and the furnace was heated to 250℃ at a heating rate of 10℃ / min and held for 120 min. Then, the temperature was increased to 400℃ at a heating rate of 2℃ / min and held for 240 min. Next, the temperature was increased to 500℃ at a heating rate of 2℃ / min and held for 240 min. Then, the temperature was increased to 800℃ at a heating rate of 5℃ / min and held for 60 min. Finally, the temperature was increased to 850℃ at a heating rate of 5℃ / min and held for 180 min. After the holding period, the temperature was decreased to 600℃ at a cooling rate of 2℃ / min and held for 60 min. After the holding period, the temperature was cooled to room temperature with the furnace. After ultrasonic cleaning, a solder film with a certain toughness was obtained, which was then cut and rolled as needed.

[0050] The average shear strength of the joint obtained by brazing YG8 cemented carbide and 316 stainless steel with porous brazing filler film in this embodiment and holding at 920°C for 10 min is 482.63 MPa.

[0051] Example 2

[0052] The porous solder film described in this embodiment is prepared according to the following steps:

[0053] 1. Prepare the slurry

[0054] PVB, Tween-20, PEG, and alcohol were weighed in a mass ratio of 1:0.8:0.8:10 to obtain a mixed slurry. 5 wt.% potassium sulfate was added to the metal powder to obtain a mixed powder. The mixed slurry and mixed powder were placed in a sealed container at a mass ratio of 1:3 and mixed in a powder mixer for 20 hours to obtain a homogeneous slurry. The metal powder consisted of the following components by weight percentage: 55% Cu, 8% Ni, 4% Mn, 5% Co, and the balance Zn. All powders were spherical with a particle size of 10 micrometers and a purity higher than 99.8%.

[0055] 2. Casting

[0056] The mixture was stirred in a powder mixer for 24 hours to obtain a uniform slurry. The slurry was then evenly coated onto a stainless steel plate using a coating tool to a thickness of 500 μm. The stainless steel plate was dried in a nitrogen atmosphere for 3 hours before the film was removed.

[0057] 3. Sintering and shaping

[0058] The membrane was placed in a vacuum sintering furnace, and the furnace was heated to 250℃ at a heating rate of 10℃ / min and held for 120 min. Then, the temperature was increased to 400℃ at a heating rate of 2℃ / min and held for 240 min. Next, the temperature was increased to 500℃ at a heating rate of 2℃ / min and held for 240 min. Then, the temperature was increased to 800℃ at a heating rate of 5℃ / min and held for 60 min. Finally, the temperature was increased to 900℃ at a heating rate of 5℃ / min and held for 180 min. After the holding period, the temperature was decreased to 600℃ at a cooling rate of 2℃ / min and held for 60 min. After the holding period, the temperature was cooled to room temperature with the furnace. After ultrasonic cleaning, a solder film with a certain toughness was obtained, which was then cut and rolled as needed.

[0059] The average shear strength of the joint obtained by brazing YG8 cemented carbide and 316 stainless steel with porous brazing filler film in this embodiment and holding at 910°C for 10 min is 503.48 MPa.

[0060] This invention discloses a porous brazing filler metal film for brazing cemented carbide and stainless steel, and its preparation method. The preparation method involves uniformly mixing brazing filler metal powder, a pore-forming agent, and a binder, followed by casting using a film scraper to obtain a filler metal film with a thickness of 100–600 micrometers. The film is then subjected to vacuum sintering and ultrasonic cleaning to obtain the porous filler metal film. This porous filler metal film has a brazing temperature range of 850–950°C, is flexible, can be rolled up and stored, and can be punched into any shape. It has a narrow solid-liquid temperature range and leaves no residue after melting. For cemented carbide and stainless steel with significantly different coefficients of thermal expansion, the porous filler metal film prepared by this invention can reduce residual stress in the brazed joint, improve joint strength, and address the problem of poor brazed joint reliability.

[0061] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for producing a porous filler metal film for brazing cemented carbide and stainless steel, characterized by, The method comprises the following steps: (1) weighing raw materials The mixed slurry is obtained by weighing the binder, surfactant, plasticizer and solvent in a mass ratio of 1:0.8:0.8:6-15, and the mixed powder is obtained by adding 5-10 wt.% of the pore-forming agent to the metal powder; (2) casting molding The mixed slurry and the mixed powder are put into a sealed container in a mass ratio of 1:2-5, mixed in a powder mixer for 10-24 h to obtain a uniform slurry, the slurry is uniformly coated on a stainless steel plate by a film scraper, the coating thickness is 100-1000 um, and the film is obtained after the stainless steel plate is dried in a nitrogen atmosphere for 2-3 h; (3) sintering molding The film is placed in a vacuum sintering furnace for sintering treatment, and then ultrasonic cleaning is performed to obtain a brazing filler metal film with certain toughness, which is cut and rolled according to needs; the metal powder in step (1) is composed of the following components by weight percentage: 50%-60% Cu, 10%-20% Ni, 0%-4% Mn, 0%-10% Co, and the balance Zn, all powders are spherical powders with a particle size of 1-100 microns, and the purity is higher than 99.8%.

2. The method for preparing a porous brazing filler metal film for brazing hard alloy and stainless steel according to claim 1, wherein the pore-forming agent in step (1) is one or more of carbon particles, polystyrene microspheres, polymethyl methacrylate microspheres, inorganic ammonium salt, and potassium sulfate.

3. The method for preparing a porous brazing filler metal film for brazing hard alloy and stainless steel according to claim 1, wherein the binder is PVB, the surfactant is Tween-20, the plasticizer is PEG or glycerol, and the solvent is alcohol.

4. The method for preparing a porous brazing filler metal film for brazing hard alloy and stainless steel according to claim 1, wherein the brazing heating method used is one or more of induction brazing, vacuum brazing, resistance brazing, and furnace brazing. The specific steps of the sintering treatment are as follows: The vacuum molybdenum sheet sintering furnace is heated at a heating rate of 1-10 ℃ / min to 200-300 ℃ for 60-360 min; then heated at a heating rate of 1-10 ℃ / min to 350-400 ℃ for 60-360 min; 5. The method for preparing a porous brazing filler metal film for brazing cemented carbide and stainless steel according to claim 1, characterized in that, then heated at a heating rate of 1-10 ℃ / min to 450-500 ℃ for 60-360 min; then heated at a heating rate of 1-10 ℃ / min to 600-800 ℃ for 60-120 min; then heated at a heating rate of 1-10 ℃ / min to 800-950 ℃ for 60-240 min, and then cooled at a cooling rate of 1-5 ℃ / min to 500-600 ℃ for 60-360 min, and then cooled to room temperature with the furnace.

6. A porous brazing filler metal film prepared by the method for preparing a porous brazing filler metal film for brazing hard alloy and stainless steel according to any one of claims 1-5. ​ ​ ​