Preparation method of high-entropy alloy laser brazing single-layer diamond grinding wheel

Abstract

The application discloses a preparation method of a high-entropy alloy laser brazing single-layer diamond grinding wheel, and comprises the following steps: a grinding wheel steel base material is mechanically processed to obtain a grinding wheel steel base; Cr, Cu, Ni-Cr-B-Si and Ti powders are ball milled to prepare high-entropy alloy powder as a brazing filler metal; a tool forming blank is prepared in the order of the grinding wheel steel base as the bottom layer, the brazing filler metal as the middle layer and diamond abrasive particles as the upper layer; the brazing filler metal is heated to melt by laser in an inert gas environment; after cooling, the diamond abrasive particles are brazed and fixed on the surface of the grinding wheel steel base to obtain the single-layer diamond grinding wheel. After laser brazing, interface reaction between the surface of the diamond abrasive particles and the molten high-entropy alloy occurs, a metal carbide layer which is firmly combined with the surface of the diamond is formed, firm chemical and metallurgical bonding between the diamond and the brazing filler metal is generated, and thus the single-layer diamond grinding wheel is prepared, and the single-layer diamond grinding wheel has the advantages of good wettability of the brazing filler metal to the diamond, high production efficiency and small thermal damage of the diamond.

Description

A method for preparing a high-entropy alloy laser brazed single-layer diamond grinding wheel Technical Field

[0001] This invention relates to the field of diamond tool manufacturing, specifically to a method for preparing a high-entropy alloy laser brazed single-layer diamond grinding wheel. Background Technology

[0002] Diamond possesses excellent properties such as high hardness, high wear resistance, good thermal conductivity, and low coefficient of friction. Therefore, diamond tools are widely used in high-speed, high-precision cutting and grinding, as well as in the efficient machining of hard and brittle materials. Brazing single-layer diamond tools achieves a strong chemical-metallurgical bond between the diamond, the filler metal, and the substrate, giving the diamond tool excellent edge height, self-sharpening ability, and grinding performance. The abrasive grains on the surface of brazed tools are easily arranged in an orderly manner, which can significantly improve work efficiency.

[0003] The commonly used brazing filler metals for brazing single-layer diamond grinding wheels are Cu-based and Ni-based active filler metals. Cu-based alloys generally use Cu-Ti alloys, which have good compatibility and wettability with diamond, easily adhere to the diamond surface, and have good thermal conductivity, allowing heat to be quickly dissipated from the brazing area to the surrounding material during laser brazing, effectively reducing thermal damage to the diamond during the brazing process. However, Cu-based alloys are difficult and expensive to prepare, are susceptible to corrosion in certain environments, and have relatively low strength and hardness, making it easy for diamond abrasive grains to detach from the filler metal, resulting in poor machinability. Ni-based alloys generally use Ni-Cr alloys, which have good affinity with diamond, ensuring a stable chemical metallurgical bond between the filler metal and diamond during the brazing process. However, Ni-based alloys have poor thermal conductivity, causing thermal stress and thermal expansion problems during laser brazing. Ni-based alloys have a high melting point, and Ni is a catalyst element that catalyzes the transformation of diamond to graphite at high temperatures. During the brazing process, Fe elements in the matrix often melt into the brazing filler metal, serving as one of the alloy components. Fe elements can improve the bonding strength between the brazing filler metal and diamond, but they are also catalyst elements, easily catalyzing the graphitization of diamond. Summary of the Invention

[0004] To address the shortcomings and deficiencies of existing technologies, the purpose of this invention is to provide a method for preparing a high-entropy alloy laser brazed single-layer diamond grinding wheel.

[0005] The above-mentioned objective of this invention is achieved through the following technical solution:

[0006] A method for preparing a high-entropy alloy laser brazed single-layer diamond grinding wheel includes the following steps:

[0007] S1. The grinding wheel steel matrix is ​​prepared by machining the grinding wheel steel matrix material;

[0008] S2. Ni-Cr-B-Si, Cr, Cu, and Ti powders are ball-milled to form high-entropy alloy powder, which is then used to obtain brazing filler metal;

[0009] S3. The tool blank is made in the following order: bottom layer is grinding wheel steel base, middle layer is brazing filler metal, and top layer is diamond abrasive grains;

[0010] S4. The brazing filler metal is heated to melt using a laser in an inert gas environment. After cooling, the diamond abrasive grains are brazed and fixed to the surface of the grinding wheel steel substrate to obtain the single-layer diamond grinding wheel.

[0011] Several existing brazing alloys have limitations when used alone. However, by using a large amount of the active elements Ti and Cr, and adding a certain proportion of Cu, Ni, and Fe elements to adjust the composition, a high-entropy alloy CrCuFeNiTi brazing alloy is formed after laser heating. This high-entropy alloy brazing alloy can form a solid solution with good toughness and plasticity, and low brittleness, avoiding the brittleness caused by the high alloying elements in conventional brazing alloys. Therefore, high-entropy alloy brazing alloys have better physical and chemical properties. To avoid Ni being difficult to melt during laser heating due to its high melting point, the Ni element in the brazing alloy is a self-fluxing Ni-Cr-B-Si alloy. The B and Si contained in this alloy effectively lower the melting point, improve the fluidity of the brazing alloy, and protect the brazing alloy from oxidation during the brazing process.

[0012] This invention utilizes a high-entropy alloy CrCuFeNiTi brazing filler metal formed by adding a large amount of active elements Ti and Cr to Cu, Ni-Cr-B-Si, along with Fe melted from the steel matrix during welding. The active elements Ti, Cr, and Fe can chemically react with the diamond surface to form a compound layer. This layer helps to form a stronger bond between the brazing filler metal and the diamond surface, and the surface carbides prevent graphitization of the diamond. Furthermore, the self-fluidizing alloy's B and Si elements improve the filler metal's fluidity and wettability, making the welding process more stable and controllable, achieving a strong chemical-metallurgical bond between the brazing filler metal and the diamond.

[0013] Using a laser with high heating efficiency and flexibility as the brazing heat source can effectively control the thermal damage of diamond abrasive grains and the thermal deformation of the matrix. Using pre-alloyed powder and elemental metal powder as brazing filler metals for laser brazing of diamond, alloying can be achieved during the brazing process, while also realizing the metallurgical bonding of diamond, brazing filler metal and matrix.

[0014] Therefore, this invention uses a laser with concentrated energy, easy control, and rapid local heating. The temperature field gradient formed by its heating is large, which can achieve the melting of high-melting-point single metals. Furthermore, the laser can penetrate transparent diamond, thus effectively avoiding thermal damage to the diamond and thermal deformation of the matrix during the heating process. The metal powder can also be alloyed during the brazing process, improving the production efficiency of diamond grinding wheels.

[0015] Further, in step S2, the mass ratio of the Ni-Cr-B-Si, Cr, Cu and Ti powders is (20-28):(17-35):(13-26):(17-32).

[0016] Further, in step S2, the Ni-Cr-B-Si powder comprises the following components by mass percentage: Cr: 9%–14%, B: 2.5%–4.5%, Si: 3%–4.5%, C: 0.1%–0.2%, with the remainder being Ni.

[0017] Furthermore, in step S2, the purity of the Cr, Cu, and Ti powders is 99.9% to 100%.

[0018] Further, in step S2, the ball milling method is to use a ball mill to ball mill the Ni-Cr-B-Si, Cr, Cu, and Ti powders at a speed of 300-500 r / min for a time of 4-6 h.

[0019] Specifically, the ball mill can be selected as the F-P2000 high-energy planetary ball mill.

[0020] Furthermore, in step S3, the thickness of the brazing filler metal and the diamond abrasive grains is 1-2 mm.

[0021] Furthermore, in step S3, the particle size of the diamond abrasive grains is 150–240 μm.

[0022] Furthermore, in step S3, the mass ratio of the brazing filler metal to the diamond abrasive grains is 10:(1-3).

[0023] Further, in step S4, the laser heating conditions are as follows: laser heating power is 600–1000W, laser scanning speed is 10–25 mm / s, defocusing distance is 30–40 mm, and spot area is 15–27 mm². 2 The overlap rate is 28-35%.

[0024] Furthermore, in step S4, the inert gas is argon, and the gas flow rate is 20-23 L / min.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. This invention adds a large amount of active elements Ti and Cr to Cu, Ni-Cr-B-Si, as well as Fe melted from the steel matrix during welding, to form a high-entropy alloy CrCuFeNiTi. The large amount of active elements in the solder can form a compound or interstitial layer with the diamond surface during laser brazing, which is beneficial to improving the connection strength between the solder and the diamond.

[0027] 2. Laser brazing is highly efficient and has little impact on the welding materials. It can braze high-melting-point filler metals without easily causing graphitization of diamond. Detailed Implementation

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0029] This invention provides a method for preparing a high-entropy alloy laser brazed single-layer diamond grinding wheel, comprising the following steps:

[0030] S1. The grinding wheel steel matrix is ​​prepared by machining the grinding wheel steel matrix material;

[0031] S2. Ni-Cr-B-Si, Cr, Cu, and Ti powders are ball-milled to form high-entropy alloy powder, which is then used to obtain brazing filler metal;

[0032] S3. The tool blank is made in the following order: bottom layer is grinding wheel steel base, middle layer is brazing filler metal, and top layer is diamond abrasive grains;

[0033] S4. The brazing filler metal is heated to melt using a laser in an inert gas environment. After cooling, the diamond abrasive grains are brazed and fixed to the surface of the grinding wheel steel substrate to obtain the single-layer diamond grinding wheel.

[0034] In a specific embodiment, the preparation method includes the following steps:

[0035] S1. Select the grinding wheel steel substrate material and prepare the grinding wheel steel substrate by machining. Use sandpaper to polish the surface to remove rust, burrs and flash. Use ethanol solution to remove oil stains from the surface of the grinding wheel steel substrate.

[0036] S2. Brazing filler metal preparation: Ni-Cr-B-Si, Cr, Cu, and Ti powders are ball-milled in a ball mill to prepare high-entropy alloy powder. The mass percentage of Ni-Cr-B-Si powder is Cr: 9-14, B: 2.5-4.5, Si: 3-4.5, C: 0.1-0.2, with the remainder being Ni. The purity of Cr, Cu, and Ti powders in the brazing filler metal is 99.9%-100%, and the mass percentage of Ni-Cr-B-Si, Cr, Cu, and Ti is (20-28):(17-35):(13-26):(17-32). The mixed powder is ball-milled using a high-energy planetary ball mill at a speed of 300-500 r / min for 4-6 h.

[0037] S3. Make tool blanks in the order of grinding wheel steel matrix, brazing filler metal, and diamond abrasive grains, wherein the thickness of brazing filler metal and diamond abrasive grains is 1-2 mm; wherein the particle size of diamond abrasive grains is 150-240 μm, and the mass ratio of brazing filler metal to diamond abrasive grains is 10:(1-3).

[0038] S4. The brazing filler metal is heated to melt using a laser. Simultaneously, argon gas is used to create a protective atmosphere for the brazing diamond and filler metal to prevent oxidation. After cooling, the diamond abrasive grains are brazed and fixed to the surface of the grinding wheel steel substrate, resulting in the finished product. The flow rate of the argon gas used as the protective gas is 20–23 L / min. The laser heating power is set to 600–1000 W, the laser scanning speed is set to 10–25 mm / s, the defocusing distance is 30–40 mm, and the spot area is 15–27 mm². 2 The overlap rate is between 28% and 35%.

[0039] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0041] Example 1

[0042] A method for preparing a high-entropy alloy laser brazed single-layer diamond grinding wheel includes the following steps:

[0043] S1. Select the grinding wheel steel substrate material and prepare the grinding wheel steel substrate by machining. Use sandpaper to polish the surface to remove rust, burrs and flash. Use ethanol solution to remove oil stains from the surface of the grinding wheel steel substrate.

[0044] S2. Brazing filler metal preparation: Ni-Cr-B-Si, Cr, Cu, and Ti powders are ball-milled in a ball mill to prepare high-entropy alloy powder. The mass percentage of Ni-Cr-B-Si powder is Cr: 9-14, B: 2.5-4.5, Si: 3-4.5, C: 0.1-0.2, with the remainder being Ni. The purity of Cr, Cu, and Ti powders in the brazing filler metal is 99.9%-100%, and the mass percentage of Ni-Cr-B-Si, Cr, Cu, and Ti is 20:17:13:17. The mixed powder is ball-milled using a high-energy planetary ball mill at a speed of 300 r / min for 4 hours.

[0045] S3. A tool blank is made in the following order: bottom layer is a steel grinding wheel substrate, middle layer is brazing filler metal, and top layer is diamond abrasive grains. The thickness of the brazing filler metal and diamond abrasive grains is 1 mm. The particle size of the diamond abrasive grains is 150 μm, and the mass ratio of brazing filler metal to diamond abrasive grains is 10:1.

[0046] S4. The brazing filler metal is heated to melt using a laser. Simultaneously, argon gas is used to create a protective atmosphere for the brazing diamond and filler metal to prevent oxidation. After cooling, the diamond abrasive grains are brazed and fixed to the surface of the grinding wheel steel substrate, resulting in the finished product. The flow rate of the argon gas used as the protective gas is 20 L / min. The laser heating power is set to 600 W, the laser scanning speed is set to 10 mm / s, the defocusing distance is 30 mm, and the spot area is 15 mm². 2 The overlap rate is 28%.

[0047] The results show that the new type of brazing filler metal can reduce the filler metal temperature and the filler metal melts more uniformly. A thin layer of carbide is formed on the diamond surface, and a strong chemical metallurgical bond can be formed between the filler metal, diamond and the matrix.

[0048] Example 2

[0049] A method for preparing a high-entropy alloy laser brazed single-layer diamond grinding wheel includes the following steps:

[0050] S1. Select the grinding wheel steel substrate material and prepare the grinding wheel steel substrate by machining. Use sandpaper to polish the surface to remove rust, burrs and flash. Use ethanol solution to remove oil stains from the surface of the grinding wheel steel substrate.

[0051] S2. Brazing filler metal preparation: Ni-Cr-B-Si, Cr, Cu, and Ti powders are ball-milled in a ball mill to prepare high-entropy alloy powder. The mass percentage of Ni-Cr-B-Si powder is Cr: 9-14, B: 2.5-4.5, Si: 3-4.5, C: 0.1-0.2, with the remainder being Ni. The purity of Cr, Cu, and Ti powders in the brazing filler metal is 99.9%-100%, and the mass percentage of Ni-Cr-B-Si, Cr, Cu, and Ti is 28:35:26:32. The mixed powder is ball-milled using a high-energy planetary ball mill at a speed of 500 r / min for 6 hours.

[0052] S3. A tool blank is made in the following order: bottom layer is a steel grinding wheel substrate, middle layer is brazing filler metal, and top layer is diamond abrasive grains. The thickness of the brazing filler metal and diamond abrasive grains is 2 mm. The particle size of the diamond abrasive grains is 240 μm, and the mass ratio of brazing filler metal to diamond abrasive grains is 10:3.

[0053] S4. The brazing filler metal is heated to melt using a laser. Simultaneously, argon gas is used to create a protective atmosphere for the brazing diamond and filler metal to prevent oxidation. After cooling, the diamond abrasive grains are brazed and fixed to the surface of the grinding wheel steel substrate, resulting in the finished product. The flow rate of the argon gas used as the protective gas is 23 L / min. The laser heating power is set to 1000 W, the laser scanning speed is set to 25 mm / s, the defocusing distance is 40 mm, and the spot area is 27 mm². 2 The overlap rate is 35%.

[0054] The results show that the new brazing filler metal can reduce the thermal damage to diamond, and the filler metal melts more uniformly, which can achieve a high-strength connection between diamond and filler metal. The diamond can achieve a better exposure height, and the brazed diamond has a good morphology and sharp edges.

[0055] Example 3

[0056] A method for preparing a high-entropy alloy laser brazed single-layer diamond grinding wheel includes the following steps:

[0057] S1. Select the grinding wheel steel substrate material and prepare the grinding wheel steel substrate by machining. Use sandpaper to polish the surface to remove rust, burrs and flash. Use ethanol solution to remove oil stains from the surface of the grinding wheel steel substrate.

[0058] S2. Brazing filler metal preparation: Ni-Cr-B-Si, Cr, Cu, and Ti powders are ball-milled in a ball mill to prepare high-entropy alloy powder. The mass percentage of Ni-Cr-B-Si powder is Cr: 9-14, B: 2.5-4.5, Si: 3-4.5, C: 0.1-0.2, with the remainder being Ni. The purity of Cr, Cu, and Ti powders in the brazing filler metal is 99.9%-100%, and the mass ratio of Ni-Cr-B-Si, Cr, Cu, and Ti is 24:25:20:25. The mixed powder is ball-milled using a high-energy planetary ball mill at a speed of 400 r / min for 5 hours.

[0059] S3. A tool blank is made in the following order: bottom layer is a steel grinding wheel substrate, middle layer is brazing filler metal, and top layer is diamond abrasive grains. The thickness of the brazing filler metal and diamond abrasive grains is 1.5 mm. The particle size of the diamond abrasive grains is 200 μm, and the mass ratio of brazing filler metal to diamond abrasive grains is 10:2.

[0060] S4. The brazing filler metal is heated to melt using a laser. Simultaneously, argon gas is used to create a protective atmosphere for the brazing diamond and filler metal to prevent oxidation. After cooling, the diamond abrasive grains are brazed and fixed to the surface of the grinding wheel steel substrate, resulting in the finished product. The flow rate of the argon gas used as the protective gas is 21.5 L / min. The laser heating power is set to 800 W, the laser scanning speed is set to 17 mm / s, the defocusing distance is 35 mm, and the spot area is 23 mm². 2 The overlap rate is 32%.

[0061] The results show that laser brazing of diamond, with relatively uniform melting of the brazing filler metal, can achieve a high-strength connection between the diamond and the filler metal, with less thermal damage to the diamond, a better exposed height of the diamond, and a well-preserved morphology and sharp edges after brazing.

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a high-entropy alloy laser brazed single-layer diamond grinding wheel, characterized in that, Includes the following steps: S1. The grinding wheel steel matrix is ​​prepared by machining. S2. Ni-Cr-B-Si, Cr, Cu, and Ti powders are ball-milled into high-entropy alloy powder to obtain brazing filler metal. The mass ratio of the Ni-Cr-B-Si, Cr, Cu, and Ti powders is (20~28):(17~35):(13~26):(17~32). The Ni-Cr-B-Si powder comprises the following components by mass percentage: Cr: 9%~14%, B: 2.5%~4.5%, Si: 3%~4.5%, C: 0.1%~0.2%, with the remainder being Ni. S3. Tool blanks are fabricated in the following order: bottom layer is the grinding wheel steel matrix, middle layer is the brazing filler metal, and top layer is diamond abrasive grains. S4. The single-layer diamond grinding wheel is obtained by laser heating the brazing filler metal to melt in an inert gas environment, followed by cooling and brazing of the diamond abrasive grains onto the surface of the grinding wheel steel substrate. The laser heating conditions are as follows: laser power of 600~1000 W, laser scanning speed of 10~25 mm / s, defocusing amount of 30~40 mm, and spot area of ​​15~27 mm². 2 The overlap rate is 28-35%.

2. The preparation method according to claim 1, characterized in that, In step S2, the purity of the Cr, Cu and Ti powders is 99.9%~100%.

3. The preparation method according to claim 1, characterized in that, In step S2, the ball milling method is to use a ball mill to mill Ni-Cr-B-Si, Cr, Cu, and Ti powders at a rotation speed of 300~500 r / min and a milling time of 4~6 h.

4. The preparation method according to claim 1, characterized in that, In step S3, the thickness of the brazing filler metal and diamond abrasive grains is 1~2 mm.

5. The preparation method according to claim 1, characterized in that, In step S3, the particle size of the diamond abrasive grains is 150~240 μm.

6. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of the brazing filler metal to the diamond abrasive grains is 10:(1~3).

7. The preparation method according to claim 1, characterized in that, In step S4, the inert gas is argon, and the gas flow rate is 20~23 L / min.