A method for laser brazing diamond abrasive grains with copper-based brazing filler metal

Abstract

The present invention relates to a method for laser brazing diamond abrasive grains with a copper-based brazing filler metal, and belongs to the field of superhard material tool manufacturing. Diamond is laser brazed using a copper-based brazing filler metal mixed with Cu, Ni, Cr, and Ti elemental metal powders. The Cr and Ti in the filler metal can improve the wettability of the filler metal to the diamond, thereby achieving a high-strength connection with the diamond. Argon is used for protection during the welding process, and nitrogen is subsequently introduced to cool the filler metal in a solid-liquid state and chemically react with it. The nitrogen gas can prevent oxidation of the brazing layer, and the nitrogen in the filler metal can react with the Cr and Ti in the filler metal at high temperatures to form nitrides such as CrN and TiN on the surface of the filler metal at high temperatures. This not only forms a nitride protective layer on the brazing layer, but also has a low cost. The manufactured brazing layer has high internal toughness and plasticity, and high surface wear resistance, thereby reducing wear of the brazing layer during tool use and extending tool life.

Description

Technical Field

[0001] The invention belongs to the field of diamond tool manufacturing, and in particular relates to a manufacturing technology for brazing single-layer diamond tools. Background Art

[0002] Diamond, known for its exceptional properties such as high hardness, high wear resistance, low friction coefficient, and strong thermal conductivity, is widely used in the manufacture of diamond tools, particularly for machining hard and brittle materials. However, traditional manufacturing processes such as sintering and electroplating fail to effectively hold the diamond, resulting in the diamond abrasive grains easily falling off during use. Brazing diamonds creates a chemical metallurgical bond between the brazing material and the diamond, improving the holding strength of the diamond abrasive grains. Brazed diamond tools have a longer lifespan and higher exposed height. Furthermore, the brazing process is largely environmentally friendly, making brazed diamond tools widely considered a superior alternative to electroplated tools.

[0003] Brazing typically uses Ni, Ag, or Cu-based filler metals containing active elements (such as Cr and Ti). Furthermore, given the wide range of applications for diamond tools, different workpiece materials and operating conditions place varying demands on tool performance. Therefore, the melting point, composition, and wear resistance requirements for brazing diamond tools differ from those for conventional filler metals, resulting in unique characteristics and diversity. Currently, Ni, Ag, and Cu-based fillers are widely used. However, Ni-based fillers have a high melting point and can significantly damage the diamond during brazing heating, thus impacting the performance and service life of diamond tools. Ag-based fillers are also expensive, making them unsuitable for large-scale production. In addition, the commonly used Ag and Cu-based solders have poor wettability on diamond, and the solubility of Cr in Ag and Cu is extremely low, resulting in delamination of CuCr or AgCr alloys or the formation of so-called pseudo-alloys. However, the solubility of C in Ag and Cu-based solders is extremely low and its melting point is low. Therefore, the chemical corrosion of Ag and Cu-based solders on diamond is relatively low. In order to improve the wettability of Ag and Cu-based solders on diamond, most of them use the active element Ti to improve the wettability of diamond. In addition, diamond tools will be subjected to high temperatures due to friction during the processing process, so brazing filler metals with suitable melting point and wear resistance are required. Since the wear resistance of Cu-based materials is poor, the tool is easily worn due to the brazing layer during the processing, resulting in excessive exposure of the diamond and falling off. By adding an appropriate amount of Ni element, the mechanical properties and high-temperature properties of the brazing filler metal can be improved. Secondly, Ni element has good wettability on diamond, and Cu and Ni are infinitely soluble in each other. In addition, the increase of Ni element in the brazing filler metal can appropriately increase the solubility of Cr. Therefore, Cu, Ni, Cr, and Ti are selected as the main elements of the brazing filler metal.

[0004] Laser brazing is easy to achieve the production of small batches of large-size tools. However, when diamond is brazed in air, the presence of oxygen causes the diamond particles to undergo severe graphitization, reducing the mechanical properties of the diamond and shortening the life of the diamond tool, or even making it unusable. Therefore, laser brazing often requires the use of a protective atmosphere to avoid oxidation of the brazing material.

[0005] Since diamond tools are subject to a lot of friction from abrasive debris during machining, the brazing layer is subject to wear, causing the diamond abrasive grains to fall off. Therefore, the brazing layer requires high wear resistance and toughness. As we all know, wear on parts starts from the surface, so surface treatment can also improve wear resistance and ensure that the brazing layer has good toughness to withstand the impact loads during tool machining. After welding, the diamond is properly cooled by passing argon gas protection while nitrogen is introduced. On the one hand, this prevents the brazing material from oxidizing. On the other hand, the nitrogen in the brazing material can react with the Cr and Ti in the brazing material at high temperatures to form nitrides such as CrN and TiN on the surface of the brazing material. This not only forms a nitride protective layer and reduces brazing wear, but also has a low cost. This technology can make the brazing material of brazed diamond tools have high internal toughness and plasticity, and good surface wear resistance.

[0006] The present invention adopts the method of mixing simple metals in proportion to manufacture the solder, which greatly reduces the cost of the solder and facilitates the control of the composition. Summary of the Invention

[0007] The present invention adopts nitrogen to protect the solder. At the same time, under high temperature conditions, the nitrogen reacts with multiple metals on the surface to form nitrides on the surface of the solder layer, thereby enhancing the wear resistance of the solder layer and maintaining good toughness of the copper-based solder solder layer.

[0008] In order to improve the wettability of the brazing material to diamond, Ti and Cr are added to the brazing material. Because diamond tools are subjected to high temperatures during processing, adding an appropriate amount of Ni element can improve the mechanical properties and high-temperature properties of the brazing material. At the same time, Ni element also has better wettability to diamond.

[0009] The present invention provides a novel method for manufacturing a single-layer diamond grinding wheel brazed with solder, comprising the following steps:

[0010] (1) The required diamond grinding wheel matrix is prepared by machining and the grinding wheel matrix is degreased and derusted.

[0011] (2) A copper-based solder is made of a mixture of Cu, Ni, Cr, and Ti elemental metal powders, wherein the mass content of Cr is 2-4%, the mass content of Ti is 8-12%, the mass content of Ni is 8-12%, and the rest is Cu.

[0012] (3) The copper-based solder and the pressure-sensitive adhesive are mixed in a weight ratio of 1:2.3 to 2.8 to prepare a solder slurry.

[0013] (4) The solder slurry and diamond abrasives are mixed in proportion and evenly coated on the surface of the grinding wheel base, wherein the particle size of the diamond abrasives is 120-450 μm, and the thickness of the coated solder slurry is 95-125% of the average particle size of the diamond abrasives.

[0014] (5) A tool forming blank is manufactured in the order of a bottom layer of a diamond grinding wheel substrate, a middle layer of solder slurry, and an upper layer of diamond abrasive grains.

[0015] (6) The power is 870-1030W, the scanning speed is 50-65mm / min, and the spot area is 15-27mm 2 The laser heats the formed blank until the brazing material melts, and then laser brazing is performed at a brazing temperature of 1040-1500°C, with argon gas introduced for protection. Another nozzle is added after the laser nozzle, and nitrogen is introduced for further protection and chemical reaction to form a nitride layer on the surface of the brazing layer. The protective gas is applied to the top of the diamond, wherein the argon is 99.99% high-purity argon with a gas flow range of 5L / min-15L / min, and the nitrogen flow range is 4L / min-17L / min. After cooling, the diamond abrasive is fixed to the surface of the substrate.

[0016] Beneficial effects of the present invention:

[0017] (1) The present invention adopts nitrogen cooling and reaction after laser welding to play an anti-oxidation role. At the same time, at high temperature, nitrogen reacts with the surface metal to generate nitride on the surface of the solder, thereby improving the wear resistance and hardness of the solder and maintaining the advantages of good internal plasticity and toughness of the solder.

[0018] (2) The present invention adopts a copper-based solder containing a certain amount of Ni, Cr, and Ti, where the active elements are Cr and Ti. This avoids the graphitization of diamond caused by a large amount of Ni in the solder, reduces the thermal damage to the diamond, and the composition of the solder can be appropriately adjusted within a certain range to adapt to different processing requirements. DETAILED DESCRIPTION

[0019] Example 1

[0020] (1) The required diamond grinding wheel matrix is prepared by machining, 65Mn steel is selected as the grinding wheel matrix, and the matrix is degreased and derusted.

[0021] (2) A copper-based brazing filler metal is prepared by mixing Cu, Ni, Cr, and Ti single-element metal powders, wherein the mass content of Cr is 2%, the mass content of Ti is 8%, the mass content of Ni is 8%, and the rest is Cu.

[0022] (3) A copper-based solder and a pressure-sensitive adhesive are mixed in a weight ratio of 1:2.5 to prepare a solder slurry.

[0023] (4) The solder slurry and diamond abrasives are evenly mixed and coated on the surface of the grinding wheel substrate according to the particle size of the diamond abrasives being 120 to 180 μm and the thickness of the coated solder slurry being 100% of the average particle size of the diamond abrasives.

[0024] (5) A tool forming blank is manufactured in the order of a bottom layer of a diamond grinding wheel substrate, a middle layer of solder slurry, and an upper layer of diamond abrasive grains.

[0025] (6) The power is 1030W, the scanning speed is 65mm / min, and the spot area is 27mm 2 The laser heats the formed blank until the brazing material melts, and then laser brazing is performed at a temperature of 1500°C, with argon gas introduced for protection. Another nozzle is added after the laser nozzle, and nitrogen is introduced for further protection and chemical reaction to form nitride covering the surface. The protective gas is applied to the top of the diamond, of which the argon is 99.99% high-purity argon, the argon flow rate is 15L / min, and the nitrogen flow rate is 17L / min. After cooling, the diamond abrasive is fixed to the surface of the substrate.

[0026] The results show that brazing diamond with a copper-based brazing filler metal containing active elements avoids the graphitization of diamond caused by a large amount of Ni in the brazing filler metal, reduces the thermal damage to the diamond, and further uses nitrogen for reaction and cooling to form a small amount of nitride wear-resistant layer on the surface of the brazing layer, thereby improving the wear resistance of the copper-based brazing filler metal.

[0027] Example 2

[0028] (1) The required diamond grinding wheel matrix is prepared by machining, 45 steel is selected as the grinding wheel matrix, and the matrix is degreased and derusted.

[0029] (2) A copper-based brazing filler metal is prepared by mixing Cu, Ni, Cr, and Ti single-element metal powders, wherein the mass content of Cr is 4%, the mass content of Ti is 12%, the mass content of Ni is 12%, and the rest is Cu.

[0030] (3) A copper-based solder and a pressure-sensitive adhesive are mixed in a weight ratio of 1:2.6 to prepare a solder slurry.

[0031] (4) The solder slurry and diamond abrasives are mixed evenly with the diamond abrasives according to the particle size of the diamond abrasives being 300 to 450 μm and the thickness of the coated solder slurry being 95% of the average particle size of the diamond abrasives, and then coated and fixed on the surface of the grinding wheel substrate.

[0032] (5) A tool forming blank is manufactured in the order of a bottom layer of a diamond grinding wheel substrate, a middle layer of solder slurry, and an upper layer of diamond abrasive grains.

[0033] (6) The power is 870W, the scanning speed is 50mm / min, and the spot area is 16mm 2 The laser heats the formed blank until the brazing material melts, and then laser brazing is performed at a temperature of 1040°C, with argon gas introduced for protection. Another nozzle is added after the laser nozzle, and nitrogen is introduced for further protection and chemical reaction to form nitride covering the surface. The protective gas is applied to the top of the diamond, of which the argon is 99.99% high-purity argon, the argon flow rate is 5L / min, and the nitrogen flow rate is 4L / min. After cooling, the diamond abrasive is fixed to the surface of the substrate.

[0034] The results show that the laser brazing of diamond using copper-based brazing filler metal and further using nitrogen for cooling and reaction can avoid oxidation and improve the wear resistance of the brazing layer. The equipment is simple and the cost is low.

[0035] Example 3

[0036] (1) The required diamond grinding wheel matrix is prepared by machining, 65Mn steel is selected as the grinding wheel matrix, and the matrix is degreased and derusted.

[0037] (2) A copper-based solder is made of a mixture of Cu, Ni, Cr, and Ti single-element metal powders, wherein the mass content of Cr is 3%, the mass content of Ti is 10%, the mass content of Ni is 10%, and the rest is Cu.

[0038] (3) A copper-based solder and a pressure-sensitive adhesive are mixed in a weight ratio of 1:2.3 to prepare a solder slurry.

[0039] (4) The brazing material slurry and diamond abrasive particles are uniformly mixed and coated on the surface of the grinding wheel substrate according to the particle size of the diamond abrasive particles being 220 to 350 μm and the thickness of the coated brazing material slurry being 95% of the average particle size of the diamond abrasive particles.

[0040] (5) A tool forming blank is manufactured in the order of a bottom layer of a diamond grinding wheel substrate, a middle layer of solder slurry, and an upper layer of diamond abrasive grains.

[0041] (6) The power is 950W, the scanning speed is 55mm / min, and the spot area is 20mm 2 The laser heats the formed blank until the brazing material melts, and then laser brazing is performed at a temperature of 1200°C, with argon gas introduced for protection. Another nozzle is added after the laser nozzle, and nitrogen is introduced for further protection and chemical reaction to form nitride covering the surface. The protective gas is applied to the top of the diamond, of which the argon is 99.99% high-purity argon, the argon flow rate is 12L / min, and the nitrogen flow rate is 10L / min. After cooling, the diamond abrasive is fixed to the surface of the substrate.

[0042] The results show that the use of copper-based brazing filler metals containing suitable active elements combined with laser brazing, and further nitrogen protection and reaction, can generate nitrides on the brazing filler metal surface to improve the wear resistance and hardness of the brazing filler metal while maintaining the advantages of good internal plasticity and toughness of the brazing filler metal.

[0043] Example 4

[0044] (1) The required diamond grinding wheel matrix is prepared by machining, 45 steel is selected as the grinding wheel matrix, and the matrix is degreased and derusted.

[0045] (2) A copper-based solder is made of a mixture of Cu, Ni, Cr, and Ti single-element metal powders, wherein the mass content of Cr is 3%, the mass content of Ti is 10%, the mass content of Ni is 10%, and the rest is Cu.

[0046] (3) A copper-based solder and a pressure-sensitive adhesive are mixed in a weight ratio of 1:2.3 to prepare a solder slurry.

[0047] (4) The brazing material slurry and diamond abrasive particles are mixed evenly with each other according to the particle size of the diamond abrasive particles being 300-400 μm and the thickness of the coated brazing material slurry being 95% of the average particle size of the diamond abrasive particles, and then coated and fixed on the surface of the grinding wheel substrate.

[0048] (5) A tool forming blank is manufactured in the order of a bottom layer of a diamond grinding wheel substrate, a middle layer of solder slurry, and an upper layer of diamond abrasive grains.

[0049] (6) The power is 950W, the scanning speed is 55mm / min, and the spot area is 20mm 2 The laser heats the formed blank until the brazing material melts, and then laser brazing is performed at a temperature of 1460°C, with argon gas introduced for protection. Another nozzle is added after the laser nozzle, and nitrogen is introduced for further protection and chemical reaction to form nitride covering the surface. The protective gas is applied to the top of the diamond, wherein the argon is 99.99% high-purity argon, the argon flow rate is 12L / min, and the nitrogen flow rate is 10L / min. After cooling, the diamond abrasive is fixed to the surface of the substrate.

[0050] The results show that the present invention uses nitrogen as one of the protective gases in the diamond laser brazing process, which can not only play an anti-oxidation role, but also improve the wear resistance of the brazing layer, and ultimately improve the performance of the brazed diamond tool.

Claims

1. A method for laser brazing diamond abrasive grains with copper-based brazing filler metal, characterized in that: The method comprises the following process steps: step 1, preparation of grinding wheel matrix: adopting machining method to prepare required diamond grinding wheel matrix, and degreasing and derusting the grinding wheel matrix; step 2, preparation of solder: adopting certain Cu, Ni, Cr, Ti to mix and prepare copper-based solder, wherein the proportion of copper-based solder is Cr mass content of 2-4%, Ti mass content of 8-12%, Ni mass content of 8-12%, and the rest is Cu; step 3, preparation of solder slurry: mixing copper-based solder and pressure-sensitive adhesive in a certain weight ratio to prepare solder slurry; step 4, coating: solder slurry and diamond abrasive grains are mixed in a certain ratio and evenly coated and fixed on the surface of grinding wheel matrix; step 5, preparing tool forming blank in the order of bottom layer as diamond grinding wheel matrix, middle layer as solder slurry, and upper layer as diamond abrasive grains; step 6, mining A laser heating tool is used to shape the blank until the brazing material melts, and then laser brazing is performed, and argon gas is introduced for protection. The laser power is 870-1030W, the scanning speed is 50-65mm / min, and the spot area is 15-27mm2. The brazing temperature is 1040-1500℃, and the protection is applied to the top of the diamond using argon gas. The argon gas is 99.99% high-purity argon gas, and the gas flow range is 5L / min-15L / min. Another nozzle is added after the laser nozzle, and nitrogen is introduced for further chemical reaction and protection. After cooling, the diamond abrasive grains are fixed on the surface of the substrate to obtain the finished product. The chemical reaction is carried out by blowing nitrogen on the top of the diamond using a nozzle. The nitrogen nozzle is 4-10mm away from the laser heat source, the nitrogen purity is 99.99%, and the flow range is 4L / min-17L / min.

2. The method for laser brazing diamond abrasive grains with a copper-based solder according to claim 1, characterized in that: The solder slurry is prepared by uniformly mixing copper-based solder and pressure-sensitive adhesive in a weight ratio of 1:2.3-2.

8.

3. The method for laser brazing diamond abrasive grains with a copper-based solder according to claim 1, characterized in that: The particle size of the diamond abrasive grains is 120-450 μm, and the thickness of the coated solder slurry is 95-125% of the average particle size of the diamond abrasive grains.