Preparation method of diamond wear-resistant coating

Abstract

The invention relates to a preparation method of a diamond wear-resistant coating. The preparation method is characterized by comprising the following steps that S1, diamond brazing filler metal and wear-resistant powder are prepared; s2, after the surface of a to-be-machined workpiece is coated with diamond brazing filler metal, the to-be-machined workpiece is dried in a constant-temperature furnace, and the to-be-machined workpiece with a diamond brazing filler metal layer is obtained; and S3, laser cladding equipment is used for melting the diamond brazing filler metal layer through laser, meanwhile, an annular nozzle is matched for feeding wear-resistant powder, and the diamond wear-resistant coating formed by combining the molten diamond brazing filler metal layer and the corresponding wear-resistant powder in a cladding mode is formed on the surface of the to-be-machined workpiece. The diamond brazing filler metal is composed of, by mass, 10%-15% of diamond and 85%-90% of nickel-based brazing filler metal powder. And the wear-resistant powder is selected from one of Stellite6, Stellite12, Incone625, and Fe90 + WC wear-resistant alloy powder. The diamond wear-resistant coating is high in strength, good in wear resistance, simple and efficient.

Description

Technical Field

[0001] The present application relates to a method for preparing a diamond wear-resistant coating. Background Art

[0002] Diamond, as a superhard abrasive, possesses extremely high hardness, good thermal conductivity, and excellent wear resistance, making it the preferred hard material for wear-resistant materials. Currently, the main methods for preparing diamond coatings include induction brazing, vacuum brazing, and laser cladding. However, traditional processing methods result in high coating porosity, prone to pores and coarse microstructure (CN 110948408A), and shorten the coating's service life. Furthermore, high temperatures during diamond coating preparation can easily lead to diamond carbonization, resulting in an uneven coating surface. Summary of the Invention

[0003] The technical problem solved by the present application is to overcome the above-mentioned deficiencies in the prior art and to provide a method for preparing a diamond wear-resistant coating.

[0004] The technical solution adopted by the present application to solve the above technical problems is: a method for preparing a diamond wear-resistant coating, which is characterized by comprising the following steps: S1: preparing diamond brazing filler metal and wear-resistant powder; S2: After coating the diamond brazing material on the surface of the workpiece to be processed, drying it in a constant temperature furnace to obtain the workpiece to be processed with a diamond brazing material layer; S3: Using laser cladding equipment, the workpiece to be processed is irradiated with laser and wear-resistant powder is fed through an annular nozzle, so that a diamond wear-resistant coating composed of a molten diamond brazing material layer and the corresponding wear-resistant powder is formed on the surface of the workpiece to be processed.

[0005] In a preferred embodiment, the diamond brazing filler metal is composed of the following components in mass percentage: 10% to 15% diamond and 85% to 90% nickel-based brazing filler metal powder.

[0006] In a preferred embodiment, the thickness of the diamond brazing filler metal coating formed after the diamond brazing filler metal is coated on the surface of the workpiece to be processed in step S2 is 0.2 mm to 1.5 mm, the drying temperature is 120° C., and the drying time is 30 min.

[0007] In a preferred embodiment, the powder feeding speed (wear-resistant powder) during laser cladding is 1.0 rad / min, and the wear-resistant powder is selected from one of Stellite 6, Stellite 12, Inconel 625, and Fe90+WC wear-resistant alloy powder.

[0008] Further preferably, the wear-resistant alloy powder is spherical with a particle size of 200-325 mesh.

[0009] In a preferred embodiment, the thickness of the diamond wear-resistant coating is not less than 1.5 mm, and can be formed by spraying wear-resistant powder multiple times (repeating step S3 multiple times so that the diamond wear-resistant coating gradually increases), and the thickness of the diamond wear-resistant coating increases by 0.5 mm to 2 mm after each step S3.

[0010] Optionally, the material of the workpiece to be processed is selected from low carbon steel, medium carbon steel or alloy steel.

[0011] Optionally, the diamond particle size is 40-400 mesh.

[0012] Optionally, the nickel-based solder powder has the following composition by mass percentage: Cr: 13.0-15.0%, B: 0.001%, Si: 0.001%, Fe: 0.0021%, C: 0.016%, P: 9.7-10.5%, Co: 0.001%, and Ni as the balance.

[0013] Optionally, the laser spot is a rectangular spot with a spot size of 5 mm*3 mm.

[0014] Optionally, the laser power is 1 kW to 5 kW, and the welding speed is 10 mm / s to 50 mm / s.

[0015] Preferably, the protective gas in the laser cladding process is argon.

[0016] In this application, the diamond brazing filler metal is a mixture of diamond powder and nickel-based brazing filler metal, which can ensure the performance and life of the diamond coating in a high-temperature environment. The brazing filler metal contains elements such as B and Si, which can improve the wettability of the diamond surface. The Ni, Cr, and Si elements in the brazing filler metal form Cr3C2, Cr7C3, and Ni-Si eutectic phases in the diamond during the welding process, ensuring that the diamond and the brazing filler metal are metallurgically bonded, thereby preventing the diamond from falling off during use.

[0017] In this application, the coaxial powder feeding and addition of wear-resistant powder can effectively prevent the laser from directly acting on the diamond surface, reduce the risk of diamond carbonization, and therefore increase the laser power, thereby preparing a thicker diamond coating. The addition of wear-resistant powder can improve the shortcomings of nickel-based brazing filler metal that are not wear-resistant enough, improve the wear resistance of the coating as a whole, and prevent the diamond from falling off due to the wear of the connecting phase. The use of this method to process the diamond coating can make the diamond evenly distributed in the thickness direction, without all floating up, resulting in a rough and easy-to-fall-off surface of the diamond coating. In addition, the heat-affected zone of this application is small, pores are not easily generated in the coating, and the porosity is low.

[0018] In this application, the porosity is evaluated by the ratio of the volume occupied by voids to the total volume of the diamond wear-resistant coating and is measured by the water displacement method.

[0019] Compared with the prior art, the present invention has the following advantages: (1) The diamond wear-resistant coating provided by this application has higher bonding strength and wear resistance, and better wear protection for key parts; (2) The diamond wear-resistant coating provided by this application has a smooth surface and low porosity, and can be multi-layered to increase the thickness of the wear-resistant coating; (3) The preparation method of the diamond wear-resistant coating provided in this application uses a method combining prefabricated diamond brazing filler metal with coaxial powder feeding to effectively avoid thermal damage to the diamond. The nickel-based brazing filler metal is responsible for wetting and bonding with the diamond interface; the wear-resistant powder is responsible for improving the wear resistance of the coating linking phase, thereby improving the overall quality of the wear-resistant coating. (4) The preparation method of the diamond wear-resistant coating provided in this application is simple and efficient, has strong adaptability to working conditions, has no requirements on the shape of parts, has a short cycle, and can be processed and repaired on site, which is conducive to large-scale industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the principle of an embodiment of the present application.

[0021] Figure 2 This is a metallographic photograph of diamond coating prepared using existing technology.

[0022] Figure 3 This is an electron microscope photo of diamond coating prepared using existing technology.

[0023] Figure 4 This is a metallographic photograph of the diamond coating prepared in the examples of this application. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below with reference to the accompanying drawings and examples. The following examples are intended to explain the present application and are not intended to limit the present application to the following examples. Where specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0025] Example 1 Step 1: Take an appropriate amount of 200-mesh BNi-7 powder with a composition of Cr: 14.02%, B: 0.001%, Si: 0.001%, Fe: 0.0021%, C: 0.016%, P: 10.18%, Co: 0.001%, and Ni as the balance to prepare a solder paste. Mix the solder paste with 40-mesh diamond powder in a mass ratio of 9:1, place the mixture in a centrifugal stirrer and stir for 10 minutes to make the composition uniform, and obtain the required diamond brazing material; then weigh a certain mass of 325-mesh Fe90 powder and 325-mesh WC powder, mix them in a mass ratio of 9.5:0.5, place them in a ball mill, and mix for 1 hour to obtain wear-resistant powder.

[0026] Step 2: evenly coat the prepared diamond brazing filler metal on the surface of the Q235 substrate, and control the thickness of the diamond brazing filler metal coating to be 1 mm, place it in an oven, adjust the oven temperature to 120°C, and dry it for 30 minutes to obtain a workpiece to be processed with a diamond brazing filler metal layer.

[0027] Step 3: Adjust the laser cladding parameters to laser power 1500W, powder feeding rate 0.6r / min, and welding speed 10mm / s, and perform laser cladding with coaxial wear-resistant powder feeding above the diamond brazing material layer to obtain a diamond wear-resistant coating.

[0028] Example 2 This embodiment provides a diamond wear-resistant coating, and its preparation method is similar to that of Example 1, except that, in step 1, the diamond mesh size is 200 mesh.

[0029] Example 3 This embodiment provides a diamond wear-resistant coating, and its preparation method is similar to that of Example 1, except that, in step 1, the diamond mesh size is 200 mesh, and the wear-resistant powder used is Stellite 12 with a particle size of 325 mesh.

[0030] Comparative Example 1 This embodiment provides a diamond wear-resistant coating, and its preparation method is similar to that of embodiment 1, except that, in step 3, only diamond brazing material is used and the diamond wear-resistant coating is prepared by vacuum brazing, without adding wear-resistant powder.

[0031] Friction and wear tests were conducted using the diamond wear-resistant coatings of Examples 1 and 2 and the diamond wear-resistant coating of Comparative Example 1. The friction and wear tests of this application were all conducted on the same wear test apparatus and under the same test conditions.

[0032] Table 1 Wear parameters and analysis results of examples and comparative examples By comparing Example 1, Example 2 and Comparative Example 1, it can be concluded that the diamond wear-resistant coating of the present application has better wear resistance than the diamond wear-resistant coating prepared by other methods.

[0033] By comparing Example 1 and Example 2, it can be concluded that the diamond wear-resistant coating of the present application has better wear resistance when the diamond particle size is finer.

[0034] By comparing Example 1 and Example 3, it can be concluded that the diamond wear-resistant coating of the present application has better wear resistance when Stellite 12 is selected as the wear-resistant powder than when Fe90+WC is selected as the wear-resistant powder.

Claims

1. A method for preparing a diamond wear-resistant coating, characterized in that The following steps are involved: S1: preparing diamond brazing filler metal and wear-resistant powder; S2: After coating the diamond brazing filler metal on the surface of the workpiece to be processed, drying it in a constant temperature furnace to obtain the workpiece to be processed with a diamond brazing filler metal layer; S3: Using laser cladding equipment, the workpiece to be processed is irradiated with laser, and wear-resistant powder is sent through an annular nozzle to form a diamond wear-resistant coating on the surface of the workpiece to be processed.

2. The method for preparing the diamond wear-resistant coating according to claim 1, wherein: The diamond brazing filler metal is composed of the following components in percentage by mass: 10% to 15% diamond and 85% to 90% nickel-based brazing filler metal powder.

3. The method for preparing the diamond wear-resistant coating according to claim 2, wherein: The wear-resistant powder is selected from one of Stellite 6, Stellite 12, Inconel 625, and Fe90+WC wear-resistant alloy powders.

4. The method for preparing the diamond wear-resistant coating according to claim 1, wherein: In the step S2, the thickness of the diamond brazing material coating formed after the diamond brazing material is coated on the surface of the workpiece to be processed is 0.2 mm to 1.5 mm, the drying temperature is 100-150° C., and the drying time is 30 minutes.

5. The method for preparing the diamond wear-resistant coating according to claim 2, wherein: The mass percentage composition of the nickel-based solder powder is: Cr: 13.0-15.0%, B: 0.001%, Si: 0.001%, Fe: 0.0021%, C: 0.016%, P: 9.7-10.5%, Co: 0.001%, and Ni: balance.

6. The method for preparing the diamond wear-resistant coating according to claim 3, wherein: The wear-resistant alloy powder is spherical with a particle size of 200-325 meshes.

7. The method for preparing the diamond wear-resistant coating according to claim 1, wherein: The powder feeding speed during laser cladding is 1.0 rad / min, the laser spot is a rectangular spot, and the spot size is 5 mm*3 mm.

8. The method for preparing the diamond wear-resistant coating according to claim 1, wherein: The laser power is 1kW to 5kW, the welding speed is 10mm / s to 50mm / s, and the protective gas during the laser cladding process is argon.

9. The method for preparing the diamond wear-resistant coating according to claim 1, wherein: The thickness of the diamond wear-resistant coating is not less than 1.5 mm.

10. The method for preparing the diamond wear-resistant coating according to claim 1, wherein: The material of the workpiece to be processed is one of low carbon steel, medium carbon steel or alloy steel.

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