Novel brazing filler metal and method for brazing superhard material through novel brazing filler metal

Abstract

The invention discloses rare earth Ho-doped nickel-based brazing filler metal and a method for brazing diamonds through the rare earth Ho-doped nickel-based brazing filler metal. The brazing filler metal comprises, by mass, 12 wt.% of Cr, 3 wt.% of B, 3 wt.% of Si, 4 wt.% of Fe, 0.5-2 wt.% of Ho and the balance Ni. The prepared brazing filler metal is good in structure and excellent in mechanical property, heat damage of brazed diamonds obtained through brazing in a vacuum brazing furnace is remarkably reduced, and abrasion test results show that brazed samples have excellent abrasion resistance and machining performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of superhard abrasive tools, and specifically relates to a rare earth Ho-doped nickel-based filler metal and a method for brazing diamond with the same. Background Art

[0002] Diamond is an abrasive with high hardness and high wear resistance, and is widely used in the production of diamond tools. It has good development potential in the cutting processing of hard and brittle materials. Compared with sintered diamond tools and electroplated diamond tools, brazed diamond tools have advantages in cutting efficiency and cutting life.

[0003] The thermal damage of diamond during brazing is an important factor restricting the service life of brazed diamond tools. The thermal damage of brazed diamond includes the erosion of diamond by the catalyst element at high temperature, the graphitization of diamond caused by high brazing temperature, and the residual thermal stress. At the same time, the exposed height of diamond abrasive grains after brazing is related to the chip space during cutting and affects the cutting efficiency. In addition, defects such as breakage and holes in diamond weaken the mechanical strength of diamond and the holding force of the matrix on diamond, resulting in the fracture and detachment of diamond, and shortening the service life of diamond tools.

[0004] Chinese invention patent ZL202410706341.4 discloses a brazing method of a rare earth-modified high-performance filler metal. The mass percentage of the basic metal components of the nickel-based filler metal containing rare earth elements is: 10.0 - 14.0% of chromium Cr, 1.0% - 5.0% of boron B, 2.0% - 6.0% of silicon Si, 1.0% - 6.0% of iron Fe, 0.05% - 3.0% of rare earth RE, and the rest is nickel Ni. An ordered layered carbide is formed on the surface of the brazed diamond particles, which is not conducive to alleviating the thermal stress suffered by diamond, and cracks are formed on the carbide layer, reducing the holding force of the filler metal on diamond. Chinese invention patent ZL202410706413.5 discloses a brazing method of a nickel-based filler metal containing scandium. The mass percentage of the basic metal components of the filler metal containing Sc is: Cr 8.0 - 12.0%, B 2.0% - 4.0%, Si 1.0% - 4.0%, Fe 3.0% - 5.0%, Cu 0 - 1.0%, Sc 0 - 4.0%, and the rest is Ni. It has high microhardness. When using the scandium-containing nickel-based filler metal for brazing, the filler metal around the diamond melts incompletely and insufficiently, and part of the filler metal adheres to the exposed surface of the diamond, affecting the cutting effect of the diamond.

[0005] The brazing temperature of nickel-based filler metals is extremely high, and the filler metals contain catalytic elements that can graphitize diamond. Therefore, it is necessary to suppress the thermal damage of diamond during brazing. When using nickel-based alloys as filler metals, it is necessary to consider both the influence of the high brazing temperature on diamond and the economy of using them as filler metals. In addition, during the use of a melting furnace, the materials to be melted are placed in a crucible and melted inside the crucible, while the vacuum system evacuates the working chamber of the furnace body to make the working environment for melting in a vacuum state. However, when using the above melting furnace to melt a large amount of materials at the same time, due to the large volume of the materials, the materials concentrated in the center and the materials scattered around cannot be heated evenly, resulting in poor melting effects.

[0006] Therefore, it is necessary to research and develop a filler metal with excellent brazing performance and an inexpensive brazed diamond tool with excellent processing performance to meet the increasing requirements for high-performance cutting tools in society. Summary of the Invention

[0007] The present invention develops a method for brazing superhard materials using a new type of filler metal. By adding rare earth element Ho, the microstructure and mechanical properties of the filler metal are improved, and good brazing performance is obtained.

[0008] The present invention achieves the above object through the following method:

[0009] A new type of filler metal, by mass percentage, comprises the following components: 12 wt.% Cr, 3 wt.% B, 3 wt.% Si, 4 wt.% Fe, 0.5 - 2 wt.% Ho, and the balance Ni.

[0010] A method for brazing superhard materials using a new type of filler metal, comprising the following steps:

[0011] Step 1: Weighing.

[0012] Weigh each component raw material by an analytical balance according to the mass percentage, with an accuracy of 0.0001 g;

[0013] Step 2: Cleaning.

[0014] Place the weighed raw materials in a beaker, add acetone to cover the raw materials, put them into an ultrasonic cleaner for cleaning for 10 - 15 min, pour out the acetone after cleaning, then pour anhydrous ethanol into the beaker and ultrasonically clean for 5 - 10 min, and then take out the raw materials and dry them;

[0015] Step 3: Melting.

[0016] Put the dried raw materials into a vacuum melting furnace. Before melting, first evacuate the inside of the melting furnace to 5 Pa by a mechanical pump, and then evacuate to 5×10 -3Below Pa, then turn off the molecular pump and mechanical pump, and then introduce high-purity argon into the furnace until the pressure in the furnace reaches -0.05 MPa. During melting, use a current intensity of 200A - 250A to fully melt the ingot. After melting, the ingot is cooled with the furnace;

[0017] Step Four: Slicing.

[0018] Obtain the solder thin sheet by cutting with a diamond wire. The length and width dimensions are 15 mm × 6 mm, and the thickness is 0.15 mm. Then gradually polish it with 320-mesh, 600-mesh, and 1000-mesh sandpapers to obtain a smooth sheet-shaped solder;

[0019] Step Five: Prepare the sample

[0020] Select the No. 45 steel substrate. Sandpaper the surface of the No. 45 steel substrate to remove the surface oxide layer and impurities. Place the No. 45 steel substrate and diamond in acetone solution and alcohol solution respectively for ultrasonic cleaning and drying. Then combine the diamond with the solder sheet and the solder sheet with the steel substrate through an organic carrier to obtain the sample

[0021] Step Six: Put the prepared sample into a molybdenum wire vacuum brazing furnace for brazing.

[0022] Use a mechanical pump and a diffusion pump to make the inside of the furnace of the molybdenum wire vacuum brazing furnace in a low vacuum state. Then heat it up at a heating rate of 10 °C per minute to 1075 - 1085 °C and keep it warm for 5 - 10 minutes, and then cool it down at a cooling rate of 10 °C per minute to 500 °C. Then cool it with the furnace, and take out the product after cooling.

[0023] Preferably, the purity of each of the Ni, Cr, B, Si, Fe, and Ho elemental substances in Step One is 99.90%.

[0024] Preferably, the diamond, the solder sheet, and the steel substrate are arranged in an upper-middle-lower form in Step Six to form a sandwich structure.

[0025] Vacuum melting furnace, including a fixed base, on the top of the fixed base is fixedly installed a vacuum chamber, on the top of the fixed base is slidably arranged a sealing cover located on one side of the vacuum chamber, on the other side of the vacuum chamber is provided a connecting pipe connected to a vacuum system, the top of the vacuum chamber is rotatably connected through a rotating sleeve, on the top of the vacuum chamber is fixedly installed a support frame located above the rotating sleeve, on the top of the vacuum chamber is fixedly installed a driving motor located in front of the rotating sleeve, the middle of the rotating sleeve is slidably connected through a lifting rod, inside the support frame is rotatably connected threaded rods located on both sides of the lifting rod, the threaded rods are threadedly connected through a lifting plate, the middle of the lifting plate is rotatably connected to the top of the lifting rod, on the top of the support frame is fixedly installed a lifting motor, the output end of the lifting motor is fixedly installed on the top of the threaded rod, the output end of the driving motor is in transmission connection with the lifting rod, on the side of the sealing cover facing the vacuum chamber is provided a crucible, and at the bottom of the lifting rod is fixedly installed a stirring paddle located directly above the crucible.

[0026] Compared with the prior art, the present patent has the following beneficial effects:

[0027] 1. The Ni-based filler metal prepared by Ho doping has significantly improved filler metal structure and properties compared with that without Ho doping. Specifically, the segregation structure in the microstructure of the filler metal is reduced, the microhardness of the filler metal is improved, and the integrity of brazing diamond particles using the Ho-doped nickel-based filler metal is better.

[0028] 2. In this vacuum melting furnace, after the crucible is moved into the vacuum chamber by setting the lifting rod, the sealing cover and the vacuum chamber are tightly sealed. Then, the inside of the vacuum chamber is evacuated through the connecting pipe, and the raw materials in the crucible are heated. After heating for a period of time, the driving motor and the lifting motor are started. The lifting motor drives the threaded rod to rotate, and then the lifting plate pushes the lifting rod to move down along the rotating sleeve, so that the stirring paddle extends into the crucible. The driving motor drives the rotating sleeve and the lifting rod to rotate through the driving gear and the driven gear, and then drives the stirring paddle to rotate, stirring the molten metal in the crucible, so that the raw materials can be heated more evenly. It has the advantage of improving the melting effect while melting a large amount of metal.

[0029] 3. In this vacuum melting furnace, when the impact hammer is set and the lifting rod and the stirring paddle are driven to rotate by rotating the sleeve, at the same time, the driving rod is driven to rotate by the first synchronous wheel, the second synchronous wheel and the synchronous belt, and the rotating shaft is driven to rotate, so that the half gear drives the rack to move towards both ends of the fixed cross bar. As the half gear rotates, the half gear is disengaged from the rack, and under the action of the return spring, the rack and the impact hammer are pulled towards the middle, so that the impact hammer impacts the outer wall of the crucible. Through the impact of the impact hammer, the raw materials adhering to the side wall of the crucible fall off, and are mixed by the rotation of the stirring paddle, improving the uniform heating of the materials, thereby further improving the melting efficiency. Description of the Drawings

[0030] Figure 1 are the metallographic diagrams of the filler metal alloys of the examples and the comparative examples under an optical microscope. Figure 1 (a) is the comparative example without doping Ho, and the filler metal structure shows columnar crystals. The nickel-based filler metal doped with 1.5 wt.% Ho is as Figure 1 (d) shows that the filler metal structure shows equiaxed crystals. The reason for this phenomenon is that the doping of Ho increases the constitutional supercooling of the filler metal, and the filler metal cools at a moderate speed.

[0031] Figure 2 are the microstructural diagrams of the filler metal alloys of the examples and the comparative examples under a scanning electron microscope. Figure 2 (a) is the nickel-based filler metal without doping rare earths. Figure 2 (d) is the filler metal alloy doped with 1.5 wt.% Ho. The structure of the filler metal alloy doped with rare earth Ho is significantly improved, and a fine eutectic structure is formed between the grains of the filler metal alloy doped with 1.5 wt.% Ho.

[0032] Figure 3 is the hardness comparison between the comparative example and the examples. The microhardness of the comparative example is only 576.8 Hv0.1. After doping Ho, the hardness of the filler metal is significantly improved. The highest microhardness of the filler metal is 716.3 Hv0.1 when doped with 1.5 wt.% Ho.

[0033] Figure 4 are the diamond particles after brazing of the comparative example and the examples. The brazed diamond particles without doping Ho are severely thermally damaged, most of the diamond particles are covered by the filler metal, and the diamond is broken at the bonding interface with the filler metal. The overall morphology of the brazed diamond particles doped with Ho is well preserved. When doped with 1.5 wt.% Ho, the surface of the diamond is intact and the exposure degree of the diamond on the filler metal is large.

[0034] Figure 5The carbide morphologies on the surface of brazed diamond particles in the examples and comparative examples are shown. The carbides on the surface of brazed diamond doped with 1.5 wt.% Ho are shorter, more disordered, have a stronger ability to withstand thermal stress, and have a smaller possibility of cracking compared to the carbides on the surface of diamond particles without Ho doping;

[0035] Figure 6 This is the overall structural schematic diagram of the present invention;

[0036] Figure 7 This is the structural schematic diagram of the vacuum chamber of the present invention;

[0037] Figure 8 This is for the Figure 2 enlarged view at A in the present invention;

[0038] Figure 9 This is the structural schematic diagram of the support frame of the present invention;

[0039] Figure 10 This is the structural schematic diagram of the lifting rod of the present invention;

[0040] Figure 11 This is the structural schematic diagram of the transmission rod of the present invention;

[0041] Figure 12 This is the partial structural schematic diagram of the fixed cross bar of the present invention;

[0042] Figure 13 This is for the Figure 8 enlarged view at B in the present invention. Specific Embodiments

[0043] By referring to the attached drawings and in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention are further described. The purpose is to help those skilled in the art have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention and facilitate its implementation.

[0044] Example 1

[0045] A method for brazing superhard materials using a novel filler metal includes the following steps:

[0046] Step 1: Weighing.

[0047] Weigh each component raw material by an analytical balance according to the mass percentage. Among them, by mass percentage, the contents of each component are: 12 wt.% Cr, 3 wt.% B, 3 wt.% Si, 4 wt.% Fe, 0.5 wt.% Ho, and the rest is Ni. The total mass of each substance is 20 g, and the accuracy is 0.0001 g;

[0048] Step 2: Cleaning.

[0049] Place the weighed raw materials in a beaker, add acetone to cover the raw materials, put them in an ultrasonic cleaner and clean for 10 minutes. After acetone cleaning, pour out the acetone, then pour anhydrous ethanol into the beaker and ultrasonically clean for 5 minutes. Subsequently, take out the raw materials and dry them;

[0050] Step 3: Melting.

[0051] Put the dried raw materials into a vacuum melting furnace (for the specific structure, refer to Example 5). Before melting, first pump the inside of the melting furnace to 5 Pa by a mechanical pump, and then pump to a vacuum of 5×10 -3 Pa or less by a molecular pump. After that, close the molecular pump and the mechanical pump, and then introduce high-purity argon into the furnace until the pressure in the furnace reaches -0.05 MPa. During melting, use a current intensity of 200 A to fully melt the ingot. After melting, the ingot is cooled with the furnace;

[0052] Step 4: Slicing.

[0053] Obtain a solder thin sheet by wire cutting with emery, with the length and width dimensions of 15 mm×6 mm and the thickness of 0.15 mm. Then gradually polish it with 320-mesh, 600-mesh, and 1000-mesh sandpapers to obtain a smooth sheet-shaped solder;

[0054] Step 5: Prepare samples

[0055] Select a No. 45 steel substrate, polish the surface of the No. 45 steel substrate with sandpaper to remove the surface oxide layer and impurities. Place the No. 45 steel substrate and diamond in acetone solution and alcohol solution respectively for ultrasonic cleaning and drying. Then combine diamond with the solder sheet and the solder sheet with the steel substrate through organic carriers respectively to obtain samples;

[0056] Step 6: Put the prepared samples into a molybdenum wire vacuum brazing furnace for brazing.

[0057] Make the inside of the molybdenum wire vacuum brazing furnace in a low vacuum state through a mechanical pump and a diffusion pump. Then heat it at a heating rate of 10 °C per minute to 1075 °C and hold for 5 minutes, and then cool it at a cooling rate of 10 °C per minute to 500 °C. After that, cool it with the furnace, and take out the product after cooling.

[0058] Example 2

[0059] A method for brazing superhard materials with a new type of solder, comprising the following steps:

[0060] Step 1: Weighing.

[0061] Weigh each component raw material by mass percentage using an analytical balance. Among them, by mass percentage, the contents of each component are: 12 wt.% Cr, 3 wt.% B, 3 wt.% Si, 4 wt.% Fe, 1 wt.% Ho, and the balance Ni. The total mass of each substance is 20 g, with a precision of 0.0001 g;

[0062] Steps two to six are the same as those in Example 1.

[0063] Example 3

[0064] A method for brazing superhard materials using a new type of filler metal, comprising the following steps:

[0065] Step one: Weighing.

[0066] Weigh each component raw material by mass percentage using an analytical balance. Among them, by mass percentage, the contents of each component are: 12 wt.% Cr, 3 wt.% B, 3 wt.% Si, 4 wt.% Fe, 1.5 wt.% Ho, and the balance Ni. The total mass of each substance is 20 g, with a precision of 0.0001 g;

[0067] Steps two to six are the same as those in Example 1.

[0068] Example 4

[0069] A method for brazing superhard materials using a new type of filler metal, comprising the following steps:

[0070] Step one: Weighing.

[0071] Weigh each component raw material by mass percentage using an analytical balance. Among them, by mass percentage, the contents of each component are: 12 wt.% Cr, 3 wt.% B, 3 wt.% Si, 4 wt.% Fe, 2 wt.% Ho, and the balance Ni. The total mass of each substance is 20 g, with a precision of 0.0001 g;

[0072] Steps two to six are the same as those in Example 1.

[0073] Example 5

[0074] Please refer to Figures 6 to 13, A vacuum melting furnace, comprising a fixed base 1. A vacuum chamber 2 is fixedly installed at the top of the fixed base 1. A sealing cover 4 is slidably arranged at the top of the fixed base 1 on one side of the vacuum chamber 2. A connecting pipe 3 connected to the vacuum system is arranged on the other side of the vacuum chamber 2. A rotating sleeve 7 is rotatably connected through the top of the vacuum chamber 2. A support frame 6 is fixedly installed at the top of the vacuum chamber 2 above the rotating sleeve 7. A driving motor 5 is fixedly installed at the top of the vacuum chamber 2 in front of the rotating sleeve 7. A lifting rod 8 is slidably connected through the middle of the rotating sleeve 7. Inside the support frame 6, threaded rods 9 are rotatably connected on both sides of the lifting rod 8. The threaded rods 9 penetrate and are threadedly connected to a lifting plate 11. The middle of the lifting plate 11 is rotatably connected to the top of the lifting rod 8. A lifting motor 10 is fixedly installed at the top of the support frame 6. The output end of the lifting motor 10 is fixedly installed with the top of the threaded rod 9. The output end of the driving motor 5 is in transmission connection with the lifting rod 8. On the side of the sealing cover 4 facing the vacuum chamber 2, there is a crucible 30. At the bottom of the lifting rod 8, a stirring paddle 12 is fixedly installed directly above the crucible 30. By setting the lifting rod 8, after moving the crucible 30 into the vacuum chamber 2, the sealing cover 4 is tightly sealed with the vacuum chamber 2. Then, the inside of the vacuum chamber 2 is evacuated through the connecting pipe 3, and the raw materials in the crucible 30 are heated. After heating for a period of time, the driving motor 5 and the lifting motor 10 are started. The lifting motor 10 drives the threaded rod 9 to rotate, so that the lifting plate 11 pushes the lifting rod 8 to move down along the rotating sleeve 7, and the stirring paddle 12 is inserted into the crucible 30. The driving motor 5 drives the rotating sleeve 7 and the lifting rod 8 to rotate through the driving gear 13 and the driven gear, and then drives the stirring paddle 12 to rotate, stirring the molten metal in the crucible 30, so that the raw materials can be heated more evenly, having the advantages of improving the melting effect while melting a large amount of metal.

[0075] As an implementation manner of the present invention, the output end of the driving motor 5 is fixedly installed with a driving gear 13. At the top of the rotating sleeve 7, a follower gear 14 is fixedly installed above the vacuum chamber 2. The follower gear 14 meshes with the driving gear 13. A guiding chute 15 is formed on the outer peripheral surface of the lifting rod 8. An integrally connected guiding protrusion 16 that is slidably connected to the inside of the guiding chute 15 is provided on the inner wall of the rotating sleeve 7.

[0076] As an implementation manner of the present invention, a fixed cross bar 17 is fixedly installed inside the vacuum chamber 2 near the connecting pipe 3. A rotating shaft 23 is rotatably connected through the middle of the fixed cross bar 17. On one side of the fixed cross bar 17, a transmission rod 18 is rotatably connected above the rotating shaft 23. The top of the transmission rod 18 is rotatably connected to the top inside the vacuum chamber 2. The top of the transmission rod 18 is in transmission connection with the bottom of the rotating sleeve 7. The bottom of the transmission rod 18 is in transmission connection with one end of the rotating shaft 23.

[0077] As an embodiment of the present invention, a second bevel gear 24 is fixedly installed at one end of the rotating shaft 23, a first bevel gear 22 is fixedly installed at the bottom of the transmission rod 18, the first bevel gear 22 is meshed with the second bevel gear 24, a second synchronous wheel 20 located inside the vacuum box 2 is fixedly installed at the top of the transmission rod 18, a first synchronous wheel 19 located inside the vacuum box 2 is fixedly installed at the bottom of the rotating sleeve 7, and the second synchronous wheel 20 is connected to the first synchronous wheel 19 through a synchronous belt 21.

[0078] As an embodiment of the present invention, the rotating shaft 23 is fixedly installed with a half gear 25 located inside the fixed cross bar 17, and the fixed cross bar 17 is internally slidably connected with a rack 26 located on the upper and lower sides of the rotating shaft 23. One end of the rack 26 is integrally connected to a connecting frame 28 located on the front and rear sides of the crucible 30, and the end of the connecting frame 28 is provided with an impact hammer 29 facing the crucible 30.

[0079] As an embodiment of the present invention, the two racks 26 are symmetrically arranged with the center of the rotating shaft 23 as the center of symmetry, and a return spring 27 is provided at the other end of the rack 26. One end of the return spring 27 is fixedly installed on the rack 26, and the other end of the return spring 27 is fixedly installed on the protrusion inside the fixed cross bar 17.

[0080] As an embodiment of the present invention, the teeth of the half gear 25 are symmetrically arranged in two sections, and the angle between the two ends of the half gear 25 is ninety degrees. The teeth of the half gear 25 are divided into two sections and mesh with the rack 26 respectively. By setting the impact hammer 29, when the lifting rod 8 and the stirring blade 12 are driven to rotate by rotating the sleeve 7, the transmission rod 18 is driven to rotate by the first synchronous wheel 19, the second synchronous wheel 20 and the synchronous belt 21, and the rotating shaft 23 is driven to rotate, so that the half gear 25 drives the rack 26 to move toward the two ends of the fixed cross bar 17. As the half gear 25 rotates, the half gear 25 and the rack 26 are loosened, and the rack 26 and the impact hammer 29 are pulled closer to the middle under the action of the reset spring 27, so that the impact hammer 29 impacts the outer wall of the crucible 30. The raw materials adhering to the side wall of the crucible 30 fall off through the impact of the impact hammer 29, and are mixed by the rotation of the stirring blade 12, thereby improving the heating uniformity of the material, thereby further improving the smelting efficiency.

[0081] As an embodiment of the present invention, an electric push rod 31 located below the vacuum box 2 is fixedly installed on the top of the fixed base 1, a movable end of the electric push rod 31 is fixedly installed with a moving frame 34, and the sealing cover 4 is fixedly installed on the top of the moving frame 34.

[0082] As an embodiment of the present invention, a guide rail 32 located on one side of the electric push rod 31 is fixedly installed on the top of the fixed base 1, and a roller 33 is provided at the bottom of the movable frame 34, and the roller 33 is in rolling contact with the guide rail 32.

[0083] As an embodiment of the present invention, the connecting frame 28 is slidably connected through the side of the fixed cross bar 17 facing the crucible 30. One end of the connecting frame 28 is fixedly installed with the rack 26, and the other ends of the two connecting frames 28 are respectively located in front of and behind the crucible 30.

[0084] It should be noted that during use,

[0085] After moving the crucible 30 into the vacuum chamber 2, the sealing cover 4 is tightened with the vacuum chamber 2. Then, the inside of the vacuum chamber 2 is evacuated through the connecting pipe 3, and the raw materials in the crucible 30 are heated. After heating for a period of time, the driving motor 5 and the lifting motor 10 are started. The lifting motor 10 drives the threaded rod 9 to rotate, so that the lifting plate 11 pushes the lifting rod 8 to move downward along the rotating sleeve 7, and the stirring paddle 12 is inserted into the crucible 30. The driving motor 5 drives the rotating sleeve 7 and the lifting rod 8 to rotate through the driving gear 13 and the driven gear, thereby driving the stirring paddle 12 to rotate and stirring the molten metal in the crucible 30. When the rotating sleeve 7 drives the lifting rod 8 and the stirring paddle 12 to rotate, at the same time, the transmission rod 18 is driven to rotate through the first synchronous wheel 19, the second synchronous wheel 20 and the synchronous belt 21, and the rotating shaft 23 is driven to rotate, so that the half gear 25 drives the rack 26 to move towards both ends of the fixed cross bar 17. As the half gear 25 rotates, the half gear 25 is disengaged from the rack 26, and under the action of the return spring 27, the rack 26 and the impact hammer 29 are pulled towards the middle, so that the impact hammer 29 impacts the outer wall of the crucible 30. Through the impact of the impact hammer 29, the raw materials adhering to the side wall of the crucible 30 fall off, and are mixed by the rotation of the stirring paddle 12, improving the heat uniformity of the material, and further improving the melting efficiency.

[0086] Comparative Example 1

[0087] Compared with the embodiment, the difference lies in that the filler metal composition in (1) is different.

[0088] Specifically as follows:

[0089] Step 1: Weighing.

[0090] Weigh each component raw material by an analytical balance according to the mass percentage. Among them, by mass percentage, the contents of each component are: 12 wt.% Cr, 3 wt.% B, 3 wt.% Si, 4 wt.% Fe, and the balance is Ni. The total mass of each substance is 20 g, and the accuracy is 0.0001 g;

[0091] Step 2: Cleaning.

[0092] Place the weighed raw materials in a beaker, add acetone to cover the raw materials, place them in an ultrasonic cleaner and clean for 15 min. After acetone cleaning, pour it out, then pour anhydrous ethanol into the beaker and ultrasonically clean for 10 min. Then take out the raw materials and dry them;

[0093] Step 3: Melting.

[0094] Put the dried raw materials into a vacuum melting furnace. Before melting, first pump the inside of the melting furnace to 5 Pa by a mechanical pump, and then pump the vacuum to below 5×10 -3 Pa by a molecular pump. After that, close the molecular pump and the mechanical pump, and then introduce high-purity argon into the furnace until the pressure in the furnace reaches -0.05 MPa. During melting, use a current intensity of 250 A to fully melt the ingot. After melting, the ingot is cooled with the furnace;

[0095] Step 4: Slicing.

[0096] Obtain the solder thin sheet by wire cutting with silicon carbide, with the length and width dimensions of 15 mm×6 mm and the thickness of 0.15 mm. Then gradually polish it with 320-mesh, 600-mesh and 1000-mesh sandpapers to obtain a smooth sheet-shaped solder;

[0097] Step 5: Prepare the sample

[0098] Select the 45# steel substrate, polish the surface of the 45# steel substrate with sandpaper to remove the surface oxide layer and impurities. Place the 45# steel substrate and diamond in acetone solution and alcohol solution respectively for ultrasonic cleaning and drying. Then combine diamond with the solder sheet and the solder sheet with the steel substrate through organic carriers to obtain the sample

[0099] Step 6: Put the prepared sample into a molybdenum wire vacuum brazing furnace for brazing.

[0100] Make the inside of the molybdenum wire vacuum brazing furnace in a low vacuum state by a mechanical pump and a diffusion pump. Then heat it up to 1085℃ at a heating rate of 10℃ per minute and keep it warm for 10 min, and then cool it down to 500℃ at a cooling rate of 10℃ per minute. After that, cool it with the furnace, and take out the product after cooling.

Claims

1. A method for brazing superhard materials using a new type of brazing filler metal, characterized in that: The steps include: Step 1: Weighing Use an analytical balance to weigh each component raw material according to mass percentage, with an accuracy of 0.0001g; Step 2: Cleaning Place the weighed raw materials in a beaker, add acetone until the raw materials are covered, put them in an ultrasonic cleaner and clean them for 10-15 minutes. Pour out the acetone after cleaning, then pour anhydrous ethanol into the beaker and ultrasonically clean them for 5-10 minutes, then take out the raw materials and dry them; Step 3: Melting The dried raw materials were placed in a vacuum melting furnace. Before melting, the furnace was evacuated to 5 Pa by a mechanical pump and then evacuated to 5 × 10 -3 Pa, then turn off the molecular pump and mechanical pump, and then introduce high-purity argon gas into the furnace until the pressure in the furnace reaches -0.05MPa. During smelting, use a current intensity of 200A-250A to fully melt the ingot. After the smelting is completed, the ingot is cooled with the furnace; Step 4: Slice The brazing material sheet was obtained by diamond wire cutting, with a length and width of 15 mm × 6 mm and a thickness of 0.15 mm, and then the sheet brazing material with a smooth surface was obtained by gradually grinding with 320 mesh, 600 mesh and 1000 mesh sandpaper; Step 5: Sample preparation Step 6: Place the prepared sample into a molybdenum wire vacuum brazing furnace for brazing.

2. A vacuum melting furnace, comprising a fixed base (1), characterized in that: A vacuum box (2) is fixedly mounted on the top of the fixed base (1); a sealing cover (4) located on one side of the vacuum box (2) is slidably mounted on the top of the fixed base (1); a connecting pipe (3) connected to a vacuum system is disposed on the other side of the vacuum box (2); a rotating sleeve (7) is rotatably connected to the top of the vacuum box (2); a support frame (6) located above the rotating sleeve (7) is fixedly mounted on the top of the vacuum box (2); a driving motor (5) located in front of the rotating sleeve (7) is fixedly mounted on the top of the vacuum box (2); and a lifting rod (8) is slidably connected to the middle of the rotating sleeve (7).

3. The vacuum melting furnace according to claim 2, characterized in that: The support frame (6) is internally rotatably connected with threaded rods (9) located on both sides of the lifting rod (8), and the threaded rods (9) are threadedly connected with a lifting plate (11), and the middle part of the lifting plate (11) is rotatably connected to the top of the lifting rod (8). A lifting motor (10) is fixedly installed on the top of the support frame (6), and the output end of the lifting motor (10) is fixedly installed on the top of the threaded rod (9), and the output end of the drive motor (5) is transmission-connected to the lifting rod (8). A crucible (30) is arranged on the side of the sealing cover (4) facing the vacuum box (2), and a stirring blade (12) located directly above the crucible (30) is fixedly installed on the bottom of the lifting rod (8).

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