Bronze-based diamond grinding wheel with high bending strength and preparation method thereof

Abstract

The invention discloses a bronze-based diamond grinding wheel with high bending strength and a preparation method of the bronze-based diamond grinding wheel, and belongs to the technical field of grinding wheel preparation. Comprising the following steps that 1, aluminum powder, iron powder, chromium powder, cobalt powder and nickel powder are weighed, the obtained mixed powder is loaded into a planetary ball mill, ball milling is conducted for 45 h, and high-entropy alloy powder is obtained; and 2, the high-entropy alloy powder, the copper powder, the copper-tin pre-alloyed powder, the titanium coating diamond abrasive and the composite additive are mixed and subjected to hot pressing sintering under the protective atmosphere after pre-pressing forming, and the bronze-based diamond grinding wheel is obtained. Through the synergistic effect of the high-entropy alloy and the composite additive, the bending strength and impact toughness of the bronze-based diamond grinding wheel are remarkably improved, meanwhile, diamond graphitization is effectively inhibited, and the grinding wheel has high strength and long service life.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of grinding wheel preparation, and particularly relates to a bronze-based diamond grinding wheel with high bending strength and a preparation method thereof. BACKGROUND

[0002] As a kind of superhard abrasive tool, the diamond grinding wheel is widely used in the high-efficiency and precise machining of hard and brittle materials such as ceramics, glass and hard alloy due to its high hardness and excellent grinding performance. Among them, the bronze-based binder diamond grinding wheel is concerned due to its high bonding strength, good holding force and good thermal conductivity.

[0003] However, the traditional bronze-based binder mainly uses copper and tin, and the overall strength and toughness are still insufficient. This leads to cracks or even breakage of the grinding wheel under high-speed and heavy-load grinding conditions due to insufficient bending strength, affecting the machining safety and the service life of the grinding wheel. In addition, in order to improve the strength, the conventional method often increases the hardness of the binder or adds hard phases (such as single metal or ceramic powder) to achieve it, but this easily leads to increased brittleness of the binder, too strong holding force on the diamond abrasive and is not conducive to the self-sharpening and updating of the abrasive grains, ultimately resulting in decreased grinding efficiency of the grinding wheel, damaged workpiece surface quality, and even workpiece burn due to the inability of the dull abrasive grains to fall off.

[0004] In the prior art, there are also methods of adding multiple elements to improve the performance of the binder, but these elements often lack synergistic effect, and cannot effectively build a strong and tough gradient transition structure inside the binder and at the interface with the diamond abrasive. At the same time, during the high-temperature sintering process, how to effectively inhibit the graphitization of diamond and achieve firm bonding between the strengthening phase and the matrix is still a challenge faced by the traditional preparation process.

[0005] Therefore, it has become a technical problem to be solved in the field to develop a bronze-based diamond grinding wheel with high bending strength, good toughness and excellent grinding performance. SUMMARY

[0006] The application aims to overcome the defects of the prior art and provides a bronze-based diamond grinding wheel with high bending strength and a preparation method thereof.

[0007] The object of the application can be achieved by the following technical solutions. A preparation method of a bronze-based diamond grinding wheel with high bending strength, comprising the following steps: Step 1: weigh aluminum powder, iron powder, chromium powder, cobalt powder and nickel powder, and put the obtained mixed powder into a planetary ball mill, ball mill for 45h to obtain high-entropy alloy powder; Step 2: the high-entropy alloy powder, copper powder, copper-tin pre-alloy powder, titanium-coated diamond abrasive, and composite additives are mixed, pre-pressed, and then hot-pressed and sintered under a protective atmosphere to obtain a bronze-based diamond grinding wheel.

[0008] More preferably, the atomic fractions of the aluminum powder, iron powder, chromium powder, cobalt powder, and nickel powder are all 20%.

[0009] More preferably, the preparation raw materials of the bronze-based diamond grinding wheel include the following components: 20-25 parts of high-entropy alloy powder, 50-60 parts of copper powder, 10-20 parts of copper-tin pre-alloy powder, 25-28 parts of titanium-coated diamond abrasive, and 2-5 parts of composite additives.

[0010] More preferably, the composite additives are uniformly mixed from boron carbide, chromium oxide, and graphite at a mass ratio of (3-4):(4-5):(1-2).

[0011] More preferably, the particle sizes of the aluminum powder, iron powder, chromium powder, cobalt powder, and nickel powder are all 10 µm; and during the ball milling process, the mass ratio of the grinding ball to the mixed powder is 15:1.

[0012] More preferably, the process parameters of the pre-pressing are as follows: cold-pressing pressure 200-250 MPa, and pressure maintaining time 5-8 min.

[0013] More preferably, the process parameters of the hot-pressing and sintering are as follows: temperature 800-850 ℃, pressure 35-40 MPa, and time 5-6 min.

[0014] The beneficial effects of the present application are as follows: In the scheme, during the hot-pressing and sintering stage, the aluminum and nickel in the high-entropy alloy efficiently interdiffuse with the copper matrix, not only effectively filling the interface gap between the copper matrix and the high-entropy alloy particles to form a dense and defect-free interface bonding layer, but also significantly hindering the dislocation movement in the copper-based binder through the effect of the high-entropy alloy particles as a strengthening phase, and inducing moderate lattice distortion, thereby comprehensively improving the overall deformation resistance of the binder. This mechanism directly endows the bronze-based diamond grinding wheel with excellent bending strength, effectively solving the problem of easy breaking of traditional copper-based binders due to insufficient strength.

[0015] Meanwhile, multi-level interface interactions occur between active elements in high-entropy alloys and composite additives: transition metal elements such as chromium and cobalt in high-entropy alloys and boron carbide in composite additives react in situ at the interface to generate dispersion-strengthened boride phases; at the same time, aluminum elements in high-entropy alloys and chromium oxide in additives undergo reduction-oxidation reactions at high temperatures, further enhancing the interface bonding strength. This multi-type interface reaction mechanism and the lattice distortion effect of high-entropy alloys form a synergistic strengthening effect, which not only significantly improves the compactness and deformation resistance of the binder, but also builds a gradient transition interface structure around the diamond abrasive.

[0016] In addition, graphite in the composite additive plays a unique role in the system, its layered structure improves powder flowability during pressing, and forms a composite interface with iron, nickel and other elements in high-entropy alloys during sintering, which has the dual functions of lubrication and strengthening, effectively regulating the tribological properties of the binder, so that the grinding wheel has excellent grinding performance while maintaining high holding force.

[0017] Finally, the mechanical alloying and low-temperature hot pressing sintering process effectively suppresses the graphitization tendency of diamond, ensuring the original sharpness and cutting performance of the abrasive particles, so that the grinding wheel has excellent grinding efficiency and process feasibility while maintaining high bending strength and high wear resistance. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0019] Embodiment one: a preparation method of a bronze-based diamond grinding wheel with high bending strength, comprising the following steps: Step 1: weigh aluminum powder, iron powder, chromium powder, cobalt powder and nickel powder, and put the obtained mixed powder into a planetary ball mill, ball mill for 45h to obtain high-entropy alloy powder; the atomic fraction of the aluminum powder, iron powder, chromium powder, cobalt powder and nickel powder is 20%, and the particle size is 10μm; during the ball milling process, the mass ratio of the grinding ball to the mixed powder is 15:1; Step 2: 20 parts of high-entropy alloy powder, 50 parts of copper powder, 10 parts of copper-tin pre-alloy powder, 25 parts of titanium-coated diamond abrasive, and 2 parts of composite additives (made of boron carbide, chromium oxide, and graphite in a mass ratio of 3:4:1) are mixed, pre-pressed (cold pressing pressure 250 MPa, pressure maintaining time 5 min), and hot-pressed sintered (temperature 850℃, pressure 40 MPa, time 6 min) under a protective atmosphere to obtain a bronze-based diamond grinding wheel.

[0020] Example Two: A preparation method of a bronze-based diamond grinding wheel with high bending strength, comprising the following steps: Step 1: Aluminum powder, iron powder, chromium powder, cobalt powder, and nickel powder are weighed and mixed, and the obtained mixed powder is loaded into a planetary ball mill for ball milling for 45 h to obtain high-entropy alloy powder; the atomic fraction of the aluminum powder, iron powder, chromium powder, cobalt powder, and nickel powder is 20%, and the particle size is 10 μm; during the ball milling process, the mass ratio of the grinding ball to the mixed powder is 15:1; Step 2: 25 parts of high-entropy alloy powder, 60 parts of copper powder, 20 parts of copper-tin pre-alloy powder, 28 parts of titanium-coated diamond abrasive, and 5 parts of composite additives (made of boron carbide, chromium oxide, and graphite in a mass ratio of 4:5:2) are mixed, pre-pressed (cold pressing pressure 250 MPa, pressure maintaining time 5 min), and hot-pressed sintered (temperature 850℃, pressure 40 MPa, time 6 min) under a protective atmosphere to obtain a bronze-based diamond grinding wheel.

[0021] Example Three: A preparation method of a bronze-based diamond grinding wheel with high bending strength, comprising the following steps: Step 1: Aluminum powder, iron powder, chromium powder, cobalt powder, and nickel powder are weighed and mixed, and the obtained mixed powder is loaded into a planetary ball mill for ball milling for 45 h to obtain high-entropy alloy powder; the atomic fraction of the aluminum powder, iron powder, chromium powder, cobalt powder, and nickel powder is 20%, and the particle size is 10 μm; during the ball milling process, the mass ratio of the grinding ball to the mixed powder is 15:1; Step 2: 22.5 parts of high-entropy alloy powder, 55 parts of copper powder, 15 parts of copper-tin pre-alloy powder, 16 parts of titanium-coated diamond abrasive, and 3 parts of composite additives (made of boron carbide, chromium oxide, and graphite in a mass ratio of 3:4:1) are mixed, pre-pressed (cold pressing pressure 250 MPa, pressure maintaining time 5 min), and hot-pressed sintered (temperature 850℃, pressure 40 MPa, time 6 min) under a protective atmosphere to obtain a bronze-based diamond grinding wheel.

[0022] Comparative Example One: No high-entropy alloy powder is added, and the specific process is as follows: 55 parts copper powder, 15 parts copper-tin pre-alloyed powder, 16 parts titanium-coated diamond abrasive, and 3 parts composite additive (made by uniformly mixing boron carbide, chromium oxide, and graphite in a mass ratio of 3:4:1) were mixed and pre-pressed (cold pressing pressure 250 MPa, holding time 5 min). Under a protective atmosphere, they were hot-pressed and sintered (temperature 850℃, pressure 40 MPa, time 6 min) to obtain a bronze-coated diamond grinding wheel.

[0023] Comparative Example 2: No compound additives were added, as follows: Step 1: Weigh aluminum powder, iron powder, chromium powder, cobalt powder, and nickel powder, and load the resulting mixed powder into a planetary ball mill. Ball mill for 45 hours to obtain high-entropy alloy powder. The atomic fraction of the aluminum powder, iron powder, chromium powder, cobalt powder, and nickel powder is 20%, and the particle size is 10μm. During the ball milling process, the mass ratio of the grinding balls to the mixed powder is 15:1. Step 2: Mix 22.5 parts of high-entropy alloy powder, 55 parts of copper powder, 15 parts of copper-tin pre-alloy powder, and 16 parts of titanium-coated diamond abrasive, pre-press it (cold pressing pressure 250MPa, holding time 5min), and hot press sinter it under a protective atmosphere (temperature 850℃, pressure 40MPa, time 6min) to obtain a bronze-coated diamond grinding wheel.

[0024] Testing experiment: The bending strength and impact strength of the bronze-coated diamond grinding wheels obtained in the examples and comparative examples were tested. The bending strength was determined using the three-point bending method, with the load at which the bronze-coated diamond grinding wheel broke measured using a universal testing machine. The impact strength was measured using an impact testing machine. The data obtained are shown in the table below. Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Bending strength (MPa) 589 591 598 510 543 Impact strength (KJ / m 2 ) 28.9 29.1 29.2 19.1 25.6 Conclusion: This invention successfully prepared bronze-based diamond grinding wheels with excellent bending and impact strength through the synergistic effect of high-entropy alloy strengthening and composite additives. A comparison of the performance of the examples and comparative examples shows that the bending strength of the examples all exceeded 589 MPa, and the impact strength exceeded 28.9 KJ / m. 2 It is significantly better than the comparative example.

[0025] Comparative Example 1, lacking the addition of high-entropy alloy powder, resulted in a significant decrease in flexural strength and impact strength. This was primarily due to the absence of the interfacial strengthening, dislocation hindering, and lattice distortion mechanisms provided by the high-entropy alloy, leading to insufficient overall strength of the binder. Comparative Example 2, without the addition of composite additives, retained some of the reinforcing effects of the high-entropy alloy. However, the lack of interfacial reactions, dispersion strengthening, and lubrication-strengthening functions promoted by the composite additives resulted in decreased interfacial bonding strength and material density, thus affecting the overall mechanical properties of the grinding wheel.

[0026] Therefore, the high-entropy alloy and the composite additive are used together, which is the key to realize high bending strength and high toughness of the grinding wheel, and the lack of one of them will cause the performance to be significantly reduced.

[0027] In the description of the specification, the description of the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0028] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific embodiments, as long as they do not deviate from the invention or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A method of producing a bronze-based diamond grinding wheel having high bending strength, characterized by, The method comprises the following steps: Step 1: weigh the aluminum powder, iron powder, chromium powder, cobalt powder and nickel powder, and put the obtained mixed powder into a planetary ball mill, ball mill for 45h to obtain high-entropy alloy powder; Step 2: mix the high-entropy alloy powder, copper powder, copper-tin pre-alloy powder, titanium-coated diamond abrasive, and composite additive, pre-press, and hot-press sintering under a protective atmosphere to obtain bronze-based diamond grinding wheel.

2. The method of claim 1, wherein the bronze-based diamond grinding wheel has a high bending strength, and the method comprises the steps of: The atomic fraction of the aluminum powder, iron powder, chromium powder, cobalt powder and nickel powder is 20%. ​ 3. The method for preparing a high-bending-strength bronze-based diamond grinding wheel according to claim 1, characterized in that, The preparation raw material of the bronze-based diamond grinding wheel comprises the following components: 20-25 parts of high-entropy alloy powder, 50-60 parts of copper powder, 10-20 parts of copper-tin pre-alloy powder, 25-28 parts of titanium-coated diamond abrasive, and 2-5 parts of composite additive.

4. The method of claim 1, wherein the bronze-based diamond grinding wheel has a high bending strength, and is characterized by, The composite additive is uniformly mixed by boron carbide, chromium oxide and graphite in a mass ratio of (3-4):(4-5):(1-2).

5. The method of claim 1, wherein the bronze-based diamond grinding wheel has a high bending strength, and is characterized by, The particle size of the aluminum powder, iron powder, chromium powder, cobalt powder and nickel powder is 10μm; and the mass ratio of the mass of the grinding ball to the mass of the mixed powder in the ball milling process is 15:

1.

6. The method of claim 1, wherein the bronze-based diamond grinding wheel has a high bending strength, and is characterized by, The process parameters of the pre-pressing are as follows: cold pressing pressure 200-250MPa, and pressure maintaining time 5-8min.

7. The method of claim 1, wherein the bronze-based diamond grinding wheel has a high bending strength, and is characterized by, The process parameters of the hot-press sintering are as follows: temperature 800-850℃, pressure 35-40MPa, and time 5-6min.

8. The bronze-based diamond grinding wheel prepared by the preparation method of the bronze-based diamond grinding wheel with high bending strength according to any one of claims 1-7.