A tantalum-reinforced nickel-based tungsten carbide wear-resistant coating and its preparation method

Abstract

The present invention belongs to the technical field of laser cladding alloy coatings, and discloses a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating and a preparation method thereof. In the present invention, NiCuBSi alloy powder and WC particles are mixed to prepare a composite powder and doped with a certain content of industrial pure tantalum spherical powder. By adjusting various process parameters of laser cladding, the grain size, crystal growth mode, WC particle dissolution behavior, distribution of residual WC particles, segregation of W element, and content, size and distribution of carbide precipitation phases in the composite coating structure are finely controlled, improving the tissue uniformity of the composite coating, reducing pores and lowering the crack sensitivity of the coating, enhancing the hardness and wear resistance of the coating, ensuring the acquisition of a nickel-based tungsten carbide composite coating with uniform structure, no obvious defects and good wear resistance, while guaranteeing the production quality and production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of laser cladding alloy coatings, and particularly to a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating and a preparation method thereof. Background Art

[0002] 42CrMo is a high-strength alloy steel with good mechanical properties and machinability, and is a commonly used material for manufacturing picks of roadheaders and shearers. As one of the important components in mining exploration engineering, picks undertake the task of rock breaking and coal falling in coal mining, roadway tunneling, and tunnel construction projects. During the working process, picks are subjected to wear, impact, and alternating stress, and their failure form is mainly wear. During the working process of picks, a large compressive stress is generated between hard abrasive particles (such as coal gangue) and the pick surface. The repeated pushing of hard abrasive particles on the surface will form micro-cutting and plowing; at the same time, the repeated extrusion of soft abrasives will cause fatigue wear on the pick surface, accelerating the wear failure of the pick. In recent years, with the continuous increase in China's coal demand, the demand and loss of picks are extremely large, and it is urgent to improve the reliability and service life of picks. Therefore, it is urgent to accelerate the research and development of the wear-resistant coating process for picks and improve the hardness and wear resistance of picks.

[0003] In response to the wear failure of picks, some researchers have used surface strengthening technologies such as electroplating (patent CN216381378U), surfacing (patent CN111975205A), and laser cladding (patent CN115786910A) to prepare wear-resistant coatings on the working surface of picks to improve the hardness and wear resistance of the working surface. Among them, laser cladding technology is currently widely used in the preparation of wear-resistant coatings for picks due to its characteristics such as controllable dilution rate, high bonding strength, fine and dense coating structure, high production efficiency, and easy realization of automated production. For the working conditions of picks and the required hardness and wear resistance, iron-based or nickel-based alloy powders are usually selected as the raw materials for laser cladding to prepare alloy coatings on the working surface of picks. Since picks have high requirements for their hardness and wear resistance, a high content of hard ceramic particles (such as WC, TiC, etc.) needs to be added to the alloy powder to improve the hardness and wear resistance of the coating. However, the addition of ceramic particles will affect the microstructure morphology of the original coating. Especially when the content of the ceramic phase is relatively high, pores and cracks are easily generated, affecting the wear and corrosion resistance of the coating. To solve the problem of the easy generation of pores and crack defects in the composite coating with a high content of ceramic particles, some scholars have proposed methods such as matrix preheating and heat preservation, external field assistance, and gradient cladding (patent CN115976390A). However, the pretreatment of the metal matrix before the preparation of the cladding layer and the change of the cladding scheme will add some processes, directly resulting in the extension of the production cycle, the increase in cost, and the decrease in production efficiency.

[0004] Therefore, how to provide a composite coating with a high content of ceramic particles and a preparation method thereof, so as to improve the microstructure and service performance of the pick tooth cladding layer, further reduce the subsequent processing procedures and improve the production efficiency, is an important research direction for current researchers. Summary of the Invention

[0005] The purpose of the present invention is to provide a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating and a preparation method thereof, to solve the problems such as easy occurrence of pores and high crack sensitivity in the preparation of wear-resistant cermet composite coatings with a high ceramic phase content by existing methods in the field of laser cladding.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, which comprises raw materials with the following mass fractions:

[0008] 25-40% of NiCuBSi alloy powder, 58-70% of WC powder, 0-12% of tantalum powder, and the mass fraction of the tantalum powder is not 0;

[0009] Among them, the NiCuBSi alloy powder comprises elements with the following mass fractions: 12.2-15% of Cu, 2.3-3.4% of B, 3.1-5.1% of Si, 2.2-2.9% of Cr, 0.023-0.075% of inevitable impurity elements, and the balance is Ni.

[0010] Preferably, in the above-mentioned tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, the particle size of the NiCuBSi alloy powder is 50-140 μm; the particle size of the WC powder is 50-130 μm; the particle size of the tantalum powder is 60-130 μm.

[0011] The present invention also provides a preparation method of the above-mentioned tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, which comprises the following steps:

[0012] (1) After the metal matrix 42CrMo alloy steel is subjected to surface pretreatment, it is reserved for later use;

[0013] Mix the NiCuBSi alloy powder, WC powder and tantalum powder to obtain a mixed powder;

[0014] (2) Adopt the coaxial annular powder feeding method to laser-clad the mixed powder on the surface of the pretreated metal matrix 42CrMo alloy steel to obtain a single-layer coating;

[0015] (3) After the single-layer coating is cooled, rotate the laser path, and adopt the same process parameters as in step (2) to laser-clad the mixed powder on the surface of the single-layer coating;

[0016] (4) Repeat step (3) until the thickness of the coating meets the required value, and a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating is obtained.

[0017] Preferably, in the method for preparing a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, the process of surface pretreatment in step (1) includes: successively grinding and polishing, degreasing, and ultrasonic cleaning the metal matrix 42CrMo alloy steel.

[0018] Preferably, in the method for preparing a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, the mixing method in step (1) is ball milling, the rotation speed of the mixing in step (1) is 120 - 220 r / min, and the mixing time in step (1) is 2 - 5 h.

[0019] Preferably, in the method for preparing a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, the process parameters of laser cladding in step (2) are: laser power is 1300 - 1800 W, scanning speed is 200 - 300 mm / min, powder feeding rate is 8 - 14 g / min, powder feeding gas flow rate is 14 - 20 L / min, shielding gas flow rate is 14 - 20 L / min, defocus amount is 6 - 12 mm, and overlapping rate is 30 - 50%.

[0020] Preferably, in the method for preparing a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, the powder feeding gas and the shielding gas during the laser cladding process in step (2) are argon with a purity of 99.99%.

[0021] Preferably, in the method for preparing a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, the rotation angle in step (3) is 80 - 95°.

[0022] Preferably, in the method for preparing a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, the thickness in step (4) is 1.4 - 2.5 mm.

[0023] From the above technical solutions, it can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention uses a NiCuBSi / WC composite powder and dopes with tantalum (Ta) element. The prepared tantalum-reinforced nickel-based tungsten carbide wear-resistant coating has good microstructure and wear resistance, and solves the problem of defects such as porosity easily generated when preparing a nickel-based tungsten carbide composite coating with a high WC content.

[0025] (2) The microstructure and phase composition of the composite coating are relatively complex. In the present invention, NiCuBSi alloy powder is used as the raw material for the bonding phase to replace the traditional NiCrBSi powder. Cu is a non-carbide forming element, and a Ni-Cu solid solution is formed during the laser cladding process, which is beneficial to improving the toughness and impact resistance of the composite coating. At the same time, it avoids the concentration of hard and brittle phases and the generation of stress concentration, reduces the crack source, and lowers the crack sensitivity of the coating structure; WC particles are used as the ceramic reinforcement phase and Ta is used as the doping element. Both WC and Ta have high hardness and wear resistance. And Ta, as one of the strong carbide forming elements, will accelerate the decarburization reaction of WC during the cladding process, change the dissolution mode of WC ceramic particles in the molten pool, promote the further dissolution of WC particles, in-situ generate TaC, form a new carbide phase and make it evenly distributed, improving the hardness and wear resistance of the composite coating;

[0026] (3) Through the composition design of the pre-coating and the optimization of the preparation process parameters, the present invention proposes a laser cladding preparation method for Ta-reinforced nickel-based tungsten carbide wear-resistant coatings. This method does not require additional processes and equipment investment, avoids the problem of excessively high production costs caused by cumbersome processes and harsh processing conditions, improves the production quality, and ensures the production efficiency; combined with the adjustment of process parameters, it improves the microstructure of the cladding layer, reduces defects such as pores, and obtains a composite coating with a short process, low porosity, low crack sensitivity, and good microstructure and wear resistance. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0028] Figure 1 Cross-sectional microstructure diagram of the nickel-based tungsten carbide coating obtained in Comparative Example 1;

[0029] Figure 2 Cross-sectional microstructure diagram of the tantalum-reinforced nickel-based tungsten carbide wear-resistant coating obtained in Example 1;

[0030] Figure 3 Cross-sectional microstructure diagram of the tantalum-reinforced nickel-based tungsten carbide wear-resistant coating obtained in Example 2;

[0031] Figure 4 Cross-sectional microstructure diagram of the tantalum-reinforced nickel-based tungsten carbide wear-resistant coating obtained in Comparative Example 2;

[0032] Figure 5 Phase composition diagrams of the coatings obtained in Comparative Examples 1-2 and Examples 1-2;

[0033] Figure 6 Average microhardness statistical charts of the coatings obtained in Comparative Examples 1-2 and Examples 1-2;

[0034] Figure 7 Microstructure diagram of the wear morphology after the friction and wear test for Comparative Example 1;

[0035] Figure 8 Microstructure diagram of the wear morphology after the friction and wear test for Example 1;

[0036] Figure 9 Microstructure diagram of the wear morphology after the friction and wear test for Example 2;

[0037] Figure 10 Microstructure diagram of the wear morphology after the friction and wear test for Comparative Example 2;

[0038] Figure 11 Results of wear rate and friction coefficient after the friction and wear test for Comparative Examples 1-2 and Examples 1-2. Detailed implementation mode

[0039] The present invention provides a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, which comprises raw materials with the following mass fractions:

[0040] 25-40% of NiCuBSi alloy powder, 58-70% of WC powder, 0-12% of tantalum powder, and the mass fraction of the tantalum powder is not 0;

[0041] Among them, the NiCuBSi alloy powder comprises elements with the following mass fractions: 12.2-15% of Cu, 2.3-3.4% of B, 3.1-5.1% of Si, 2.2-2.9% of Cr, 0.023-0.075% of inevitable impurity elements, and the balance is Ni.

[0042] In the present invention, the mass fraction of the NiCuBSi alloy powder is preferably 26-37%, more preferably 32-37%, and still more preferably 32%.

[0043] In the present invention, the mass fraction of the WC powder is preferably 60-67%, more preferably 60-63%, and still more preferably 63%.

[0044] In the present invention, the mass fraction of the tantalum powder is preferably 3-8%, more preferably 3-5%, and still more preferably 5%.

[0045] In the present invention, the mass fraction of Cu in the NiCuBSi alloy powder is preferably 12.8-14.5%, more preferably 13.6-14.2%, and still more preferably 14%.

[0046] In the present invention, the mass fraction of B in the NiCuBSi alloy powder is preferably 2.5-3.2%, more preferably 2.8-3%, and still more preferably 3%.

[0047] In the present invention, the mass fraction of Si in the NiCuBSi alloy powder is preferably 3.5 - 4.8%, more preferably 3.8 - 4.2%, and still more preferably 4.1%.

[0048] In the present invention, the mass fraction of Cr in the NiCuBSi alloy powder is preferably 2.4 - 2.8%, more preferably 2.5 - 2.7%, and still more preferably 2.6%.

[0049] In the present invention, the particle size of the NiCuBSi alloy powder is preferably 50 - 140 μm.

[0050] In the present invention, the WC powder is preferably spherical, and the particle size of the WC powder is preferably 50 - 130 μm.

[0051] In the present invention, the tantalum powder is preferably spherical powder with a purity of 99.9%, and the particle size of the tantalum powder is preferably 60 - 130 μm.

[0052] The present invention also provides a method for preparing the tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, comprising the following steps:

[0053] (1) After the surface of the metal substrate 42CrMo alloy steel is pretreated, it is reserved for use;

[0054] Mix the NiCuBSi alloy powder, WC powder and tantalum powder to obtain a mixed powder;

[0055] (2) By means of coaxial annular powder feeding, laser-clad the mixed powder on the surface of the pretreated metal substrate 42CrMo alloy steel to obtain a single-layer coating;

[0056] (3) After the single-layer coating is cooled, rotate the laser path, and laser-clad the mixed powder on the surface of the single-layer coating with the same process parameters as in step (2);

[0057] (4) Repeat step (3) until the thickness of the coating meets the required value to obtain the tantalum-reinforced nickel-based tungsten carbide wear-resistant coating.

[0058] In the present invention, the metal substrate 42CrMo alloy steel in step (1) preferably contains the following elements by mass fraction: C 0.38 - 0.45%, Si 0.17 - 0.37%, Mn 0.50 - 0.80%, S ≤ 0.035%, P ≤ 0.035%, Cr 0.90 - 1.20%, Ni ≤ 0.30%, Cu ≤ 0.30%, Mo 0.15 - 0.25%, and the balance is Fe.

[0059] In the present invention, the metal matrix 42CrMo alloy steel in step (1) is preferably cut before use. The present invention does not limit the parameters of the cutting, and a scheme well-known to those skilled in the art can be adopted.

[0060] In the present invention, the instrument used for the cutting is preferably a wire electrical discharge machine.

[0061] In the present invention, the process of the surface pretreatment in step (1) preferably includes: the metal matrix 42CrMo alloy steel is polished, degreased, and ultrasonically cleaned in sequence.

[0062] In the present invention, the process of the polishing preferably includes: grinding, rust removal, and deburring in sequence.

[0063] In the present invention, the instruments used for the polishing are preferably an angle grinder and a metal processing surface grinder.

[0064] In the present invention, the aids used for the degreasing are preferably anhydrous ethanol and acetone.

[0065] In the present invention, the aid used for the ultrasonic cleaning is preferably anhydrous ethanol.

[0066] The present invention does not limit the parameters in the polishing, degreasing, and ultrasonic cleaning, and a scheme well-known to those skilled in the art can be adopted.

[0067] In the present invention, after the surface pretreatment in step (1), drying is preferably further included. The present invention does not limit the parameters of the drying, and a scheme well-known to those skilled in the art can be adopted.

[0068] In the present invention, the mixing method in step (1) is preferably ball milling, and the instrument used for the ball milling is preferably a planetary ball mill.

[0069] In the present invention, the rotation speed of the mixing in step (1) is preferably 120 - 220 r / min, more preferably 150 - 200 r / min, and even more preferably 170 r / min; the mixing time in step (1) is preferably 2 - 5 h, more preferably 3 - 4 h, and even more preferably 3 h.

[0070] The present invention does not limit the ball milling tank and ball milling beads during the ball milling, and a scheme well-known to those skilled in the art can be adopted. Specifically, in the examples of the present invention, the ball milling tank is a vacuum stainless steel ball milling tank, and the ball milling beads are stainless steel balls.

[0071] In the present invention, after the mixing in step (1), vacuum drying is preferably further included. The present invention does not limit the parameters of the vacuum drying, and a scheme well-known to those skilled in the art can be adopted.

[0072] In the present invention, the process parameters of the laser cladding in step (2) are preferably as follows: the laser power is 1300 - 1800 W, the scanning speed is 200 - 300 mm / min, the powder feeding rate is 8 - 14 g / min, the flow rate of the powder feeding gas is 14 - 20 L / min, the flow rate of the shielding gas is 14 - 20 L / min, the defocus amount is 6 - 12 mm, and the overlapping rate is 30 - 50%;

[0073] More preferably, the laser power is 1600 - 1800 W, the scanning speed is 240 - 260 mm / min, the powder feeding rate is 10 - 11 g / min, the flow rate of the powder feeding gas is 16 - 18 L / min, the flow rate of the shielding gas is 18 - 20 L / min, the defocus amount is 9 - 11 mm, and the overlapping rate is 35 - 40%;

[0074] Even more preferably, the laser power is 1600 W, the scanning speed is 250 mm / min, the powder feeding rate is 10 g / min, the flow rate of the powder feeding gas is 18 L / min, the flow rate of the shielding gas is 20 L / min, the defocus amount is 10 mm, and the overlapping rate is 35%.

[0075] In the present invention, the powder feeding gas and the shielding gas in the laser cladding process of step (2) are preferably argon gas with a purity of 99.99%.

[0076] In the present invention, the cooling temperature in step (3) is preferably 15 - 25 °C, more preferably 18 - 22 °C, and even more preferably 20 °C.

[0077] In the present invention, the rotating laser path in step (3) is preferably clockwise rotation or counterclockwise rotation.

[0078] In the present invention, the rotation angle in step (3) is preferably 80 - 95 °, more preferably 85 - 90 °, and even more preferably 90 °.

[0079] In the present invention, the thickness in step (4) is preferably 1.4 - 2.5 mm, more preferably 1.8 - 2.2 mm, and even more preferably 2 mm.

[0080] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0081] Example 1

[0082] This example provides a tantalum - enhanced nickel - based tungsten carbide wear - resistant coating, which contains the following raw materials:

[0083] 32 wt% of NiCuBSi alloy powder, 63 wt% of spherical WC ceramic powder, and 5 wt% of industrial spherical tantalum powder with a purity of 99.9%;

[0084] The NiCuBSi alloy powder contains elements with the following mass fractions: Cu 14%, B 3%, Si 4.1%, Cr 2.6%, unavoidable impurity elements 0.06%, and the balance is Ni;

[0085] The particle size of the NiCuBSi alloy powder is 50 - 120 μm; the particle size of the WC ceramic powder is 50 - 130 μm; the particle size of the tantalum powder is 60 - 140 μm.

[0086] This embodiment also provides a method for preparing a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, including the following steps:

[0087] (1) Use a wire electrical discharge machine to cut the metal substrate 42CrMo alloy steel into a cuboid specimen of 50×50×10 (unit: mm). Use an angle grinder and a metal processing surface grinder to polish, remove rust, and deburr the surface of the specimen to be processed. Then use anhydrous ethanol and acetone to remove the oil stains on each surface of the substrate, and finally put it into an anhydrous ethanol ultrasonic cleaning tank for ultrasonic cleaning and drying for standby;

[0088] Put the NiCuBSi alloy powder, spherical WC ceramic powder, and spherical tantalum powder into a planetary ball mill according to the mass fraction. The ball mill tank is a vacuum stainless steel ball mill tank, and the grinding ball material is 304 stainless steel. Carry out hybrid ball milling at 170 r / min for 3 h to obtain a hybrid powder, and finally put it into a vacuum drying oven for drying for standby;

[0089] (2) Pour the hybrid powder prepared and vacuum-dried in step (1) into the powder cylinder of the powder feeder. Adopt the coaxial annular powder feeding method. Utilize the high-energy irradiation of the laser and the heat transfer of the metal powder to clad the hybrid powder on the surface of the metal substrate processed in step (1) to obtain a single-layer coating; during the laser cladding process, the processing parameters are: laser power is 1600 W, scanning speed is 250 mm / min, powder feeding rate is 10 g / min, powder feeding gas flow rate is 18 L / min, shielding gas is 20 L / min, defocus amount is 10 mm, overlap rate is 35%, and industrial Ar gas with a purity of 99.99% is used as the powder feeding gas and shielding gas;

[0090] (3) After the single-layer coating prepared in step (2) is cooled to 20 °C, rotate the laser path clockwise by 90°, and use the same laser cladding process parameters as in step (2) to laser clad the hybrid powder on the surface of the single-layer coating;

[0091] (4) Repeat step (3) to prepare and stack the coating multiple times until the total thickness of the coating reaches 2 mm, obtaining a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating.

[0092] Example 2

[0093] This example provides a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, which contains the following raw materials:

[0094] 37 wt% of NiCuBSi alloy powder, 60 wt% of spherical WC ceramic powder, and 3 wt% of industrial spherical tantalum powder with a purity of 99.9%;

[0095] The NiCuBSi alloy powder contains the following elements by mass fraction: Cu 13%, B 3.1%, Si 3.4%, Cr 2.7%, unavoidable impurity elements 0.068%, and the balance is Ni;

[0096] The particle size of the NiCuBSi alloy powder is 50 - 120 μm; the particle size of the WC ceramic powder is 50 - 130 μm; the particle size of the tantalum powder is 60 - 140 μm.

[0097] This example also provides a method for preparing a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating. The difference from Example 1 is that: in step (1), the raw materials for ball milling and mixing are modified to the raw materials of this example, the rotation speed of the mixing ball milling in step (1) is changed to 180 r / min, and the processing parameters of laser cladding in step (2) are changed to: laser power is 1700 W, scanning speed is 240 mm / min, powder feeding rate is 11 g / min, powder feeding gas flow rate is 18 L / min, protective gas is 20 L / min, defocus amount is 10 mm, overlapping rate is 40%. In step (3), the processing parameters of laser cladding are modified to the process parameters in step (2) of this example, and other parameters and conditions are the same as those in Example 1.

[0098] Comparative Example 1

[0099] This comparative example provides a nickel-based tungsten carbide coating, which contains the following raw materials:

[0100] 40 wt% of NiCuBSi alloy powder, 60 wt% of spherical WC ceramic powder;

[0101] The NiCuBSi alloy powder contains the following elements by mass fraction: Cu 14.7%, B 2.6%, Si 3.1%, Cr 2.4%, unavoidable impurity elements 0.072%, and the balance is Ni;

[0102] The particle size of the NiCuBSi alloy powder is 50 - 120 μm; the particle size of the WC ceramic powder is 50 - 130 μm.

[0103] This comparative example also provides a method for preparing a nickel-based tungsten carbide coating, which differs from Example 1 in that: the raw materials mixed by ball milling in step (1) are modified to the raw materials of this comparative example, the time for mixed ball milling in step (1) is changed to 2.5 h, and the processing parameters of laser cladding in step (2) are changed to: laser power of 1600 W, scanning speed of 280 mm / min, powder feeding rate of 11 g / min, powder feeding gas flow rate of 17 L / min, protective gas of 18 L / min, defocusing amount of 10 mm, overlap rate of 40%, and the processing parameters of laser cladding in step (3) are modified to the process parameters in step (2) of this comparative example, and other parameters and conditions are the same as those in Example 1.

[0104] Comparative Example 2

[0105] This comparative example provides a tantalum-doped nickel-based tungsten carbide wear-resistant coating, comprising the following raw materials:

[0106] NiCuBSi alloy powder 26wt%, spherical WC ceramic powder 60wt%, industrial spherical tantalum powder with a purity of 99.9% 14wt%;

[0107] The NiCuBSi alloy powder contains the following elements in mass fractions: Cu 15%, B 3.2%, Si 3.7%, Cr 2.3%, unavoidable impurity elements 0.07%, and the balance Ni;

[0108] The particle size of the NiCuBSi alloy powder is 50-120 μm; the particle size of the WC ceramic powder is 50-130 μm; and the particle size of the tantalum powder is 60-140 μm.

[0109] The present comparative example also provides a method for preparing a tantalum-doped nickel-based tungsten carbide wear-resistant coating, which differs from Example 1 in that: the raw materials mixed by ball milling in step (1) are modified to the raw materials of the present comparative example; the processing parameters of the laser cladding in step (2) are changed to: laser power of 1800 W, scanning speed of 260 mm / min, powder feeding rate of 11 g / min, powder feeding gas flow rate of 18 L / min, protective gas of 19 L / min, defocusing amount of 10 mm, overlap rate of 40%; the processing parameters of the laser cladding in step (3) are modified to the process parameters in step (2) of the present comparative example; and other parameters and conditions are the same as those in Example 1.

[0110] The cross-sectional microstructure of the nickel-based tungsten carbide coating obtained in Comparative Example 1 is shown in Figure 1 As shown. Figure 1 It can be seen that in Comparative Example 1, due to the high content of ceramic particles, the molten pool has high viscosity and poor fluidity during the cladding process, which makes it difficult for the gas generated in the molten pool to escape and there are many pores inside the organization. The cross-sectional microstructure diagram of the tantalum-reinforced nickel-based tungsten carbide wear-resistant coating obtained in Example 1 is shown in FIG. Figure 2 As shown.Figure 2 It can be seen that the cladding layer in Example 1 has a uniform structure, with a small amount of pores generated inside and no cracks. The cross-sectional microstructure diagram of the tantalum-reinforced nickel-based tungsten carbide wear-resistant coating obtained in Example 2 is as shown in Figure 3 the following figure. From Figure 3 this, it can be seen that there are relatively few pore defects in the cladding layer structure of Example 2. The cross-sectional microstructure diagram of the tantalum-doped nickel-based tungsten carbide wear-resistant coating obtained in Comparative Example 2 is as shown in Figure 4 the following figure. From Figure 4 this, it can be seen that there are relatively large pore defects in the cladding layer structure of Comparative Example 2.

[0111] The phase compositions of the coatings obtained in Comparative Examples 1-2 and Examples 1-2 are as shown in Figure 5 the following figure. The results show that Comparative Example 1 is mainly composed of γ matrix phase, Ni3Fe phase, WC phase, W2C phase, M6C and FeW3C phases; Examples 1-2 and Comparative Example 2 are mainly composed of γ matrix phase, Ni3Fe phase, WC phase, W2C phase, M6C phase, FeW3C and TaC phases.

[0112] Figure 6 The following figure is the statistical chart of the average microhardness of the coatings obtained in Comparative Examples 1-2 and Examples 1-2. It can be seen that the average microhardness value of Comparative Example 1 is 450 HV 0.2 , the average microhardness value of Example 1 is 640 HV 0.2 , the average microhardness value of Example 2 is 530 HV 0.2 , and the average microhardness value of Comparative Example 2 is 420 HV 0.2 .

[0113] The pin-on-disc friction and wear experiment test was carried out on the coating obtained in Comparative Example 1 under the conditions of a load of 50 N, a rotation speed of 300 r / min, and a time of 20 min. The coating after the experiment is as shown in Figure 7 the following figure. It can be seen from this that features such as delamination, spalling, oxidation and plowing appeared in Comparative Example 1, and the wear mechanism is a combination of adhesive wear, oxidative wear and abrasive wear, among which the proportion of adhesive wear is relatively large. The pin-on-disc friction and wear experiment was carried out on Example 1 under the same conditions. The coating after the experiment is as shown in Figure 8 the following figure. It can be seen from this that, compared with Comparative Example 1, the wear mechanism of Example 1 is a combination of abrasive wear, oxidative wear and adhesive wear, among which the proportion of abrasive wear is relatively large. The pin-on-disc friction and wear experiment was carried out on Example 2 under the same conditions. The coating after the experiment is as shown in Figure 9 the following figure. It can be seen from this that, compared with Comparative Example 1, the wear mechanism of Example 2 is a combination of abrasive wear, oxidative wear and adhesive wear, among which the degree of adhesive wear is relatively weakened compared with Example 1, and the degree of abrasive wear is relatively enhanced. The pin-on-disc friction and wear experiment was carried out on Comparative Example 2 under the same conditions. The coating after the experiment is as shown in Figure 10As shown, it can be seen that, compared with Comparative Example 1, the wear mechanism of Comparative Example 2 is a combination of abrasive wear, oxidative wear and adhesive wear, among which the degree of adhesive wear is relatively enhanced compared with Comparative Example 1, and the degree of abrasive wear is relatively weakened.

[0114] The coating wear rate results calculated from the friction work, wear mass and volume loss of Comparative Examples 1-2 and Examples 1-2 are as Figure 11 shown. It can be seen that the coatings obtained in Examples 1-2 have good wear resistance. Compared with Comparative Example 1, the wear resistance of Example 1 is improved by 45%; the wear resistance of Example 2 is improved by 23%. While the wear resistance of Comparative Example 2 is poor, which is reduced by 11% compared with Comparative Example 1.

[0115] Generally speaking, in the current prior art for preparing nickel-based tungsten carbide wear-resistant coatings, due to the high requirements for hardness and wear resistance of picks, the proportion of WC ceramic phase used also increases. However, there are differences in melting point, tensile strength and thermal physical parameters between nickel-based self-fluxing alloy powder and WC ceramic particles, resulting in defects such as pores being easily generated in the high-content ceramic phase composite coating. In related research, methods such as matrix preheating and heat preservation, external field assistance and gradient cladding are mostly used to suppress the generation of defects in the composite coating, and there is less research on improving the microstructure and wear resistance of the composite coating by doping with non-rare earth elements.

[0116] Through the design and optimization of the composition of the cladding powder material in the early stage, the present invention proposes a method for preparing a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating by laser cladding. Mix NiCuBSi alloy powder and WC particles to prepare a composite powder and dope a certain content of industrial pure tantalum spherical powder, adjust the process parameters of laser cladding, and refine and control the grain size, crystal growth mode, WC particle dissolution behavior, distribution of residual WC particles, segregation of W element, and content, size and distribution of carbide precipitates in the composite coating microstructure, improve the microstructure uniformity of the composite coating, reduce pores, reduce the crack sensitivity of the coating, improve the hardness and wear resistance of the coating, and ensure the acquisition of a nickel-based tungsten carbide composite coating with uniform microstructure, no obvious defects and good wear resistance; at the same time, by combining the composition design and process parameter optimization, the relationship between the microstructure and properties of the cladding layer, powder composition and process parameters is successfully established, and the problem that the coating is prone to defects such as holes when adding a high content of WC ceramic particles is initially solved, and while improving the microstructure uniformity of the coating and the wear resistance of the coating, the production quality and production efficiency are ensured.

[0117] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A tantalum-reinforced nickel-based tungsten carbide wear-resistant coating, characterized in that, Raw materials containing the following mass fractions: 26 - 37% of NiCuBSi alloy powder, 60 - 67% of WC powder, 5 - 12% of tantalum powder; The particle size of the NiCuBSi alloy powder is 50 - 140μm; the particle size of the WC powder is 50 - 130μm; the particle size of the tantalum powder is 60 - 130μm; Among them, the NiCuBSi alloy powder contains elements with the following mass fractions: 12.2 - 15% of Cu, 2.3 - 3.4% of B, 3.1 - 5.1% of Si, 2.2 - 2.9% of Cr, 0.023 - 0.075% of inevitable impurity elements, and the balance is Ni; The preparation method of the tantalum - enhanced nickel - based tungsten carbide wear - resistant coating includes the following steps: (1) The metal substrate 42CrMo alloy steel is surface - pretreated and then reserved; Mix the NiCuBSi alloy powder, WC powder and tantalum powder to obtain a mixed powder; (2) By means of coaxial annular powder feeding, laser - clad the mixed powder on the surface of the pretreated metal substrate 42CrMo alloy steel to obtain a single - layer coating; (3) After the single - layer coating cools, rotate the laser path, and using the same process parameters as in step (2), laser - clad the mixed powder on the surface of the single - layer coating; (4) Repeat step (3) until the thickness of the coating meets the required value to obtain the tantalum - enhanced nickel - based tungsten carbide wear - resistant coating; The process parameters of the laser cladding in step (2) are: laser power is 1300 - 1800W, scanning speed is 200 - 300mm / min, powder feeding rate is 8 - 14g / min, the flow rate of the powder - feeding gas is 14 - 20L / min, the flow rate of the protective gas is 14 - 20L / min, defocus amount is 6 - 12mm, and the overlapping rate is 30 - 50%; the rotation angle in step (3) is 80 - 95°.

2. The preparation method of a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating according to claim 1, characterized in that, Including the following steps: (1) The metal substrate 42CrMo alloy steel is surface - pretreated and then reserved; Mix the NiCuBSi alloy powder, WC powder and tantalum powder to obtain a mixed powder; (2) By means of coaxial annular powder feeding, laser - clad the mixed powder on the surface of the pretreated metal substrate 42CrMo alloy steel to obtain a single - layer coating; (3) After the single - layer coating cools, rotate the laser path, and using the same process parameters as in step (2), laser - clad the mixed powder on the surface of the single - layer coating; (4) Repeat step (3) until the thickness of the coating meets the required value to obtain the tantalum - enhanced nickel - based tungsten carbide wear - resistant coating; Among them, the mixing method in step (1) is ball - milling, the rotation speed of the mixing in step (1) is 120 - 220r / min, and the mixing time in step (1) is 2 - 5h; The process parameters of the laser cladding described in step (2) are as follows: the laser power is 1300 - 1800 W, the scanning speed is 200 - 300 mm / min, the powder feeding rate is 8 - 14 g / min, the flow rate of the powder feeding gas is 14 - 20 L / min, the flow rate of the shielding gas is 14 - 20 L / min, the defocus amount is 6 - 12 mm, and the overlapping rate is 30 - 50%; the rotation angle described in step (3) is 80 - 95°.

3. The preparation method of a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating according to claim 2, wherein, The process of the surface pretreatment described in step (1) includes: the metal matrix 42CrMo alloy steel is polished, degreased, and ultrasonically cleaned in sequence.

4. The preparation method of a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating according to claim 2, characterized in that, The powder feeding gas and the shielding gas in the laser cladding process described in step (2) are argon with a purity of 99.99%.

5. The preparation method of a tantalum-reinforced nickel-based tungsten carbide wear-resistant coating according to claim 2 or 4, characterized in that, The thickness described in step (4) is 1.4 - 2.5 mm.

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