WC particle reinforced nickel-based composite wear-resistant coating powder and preparation method thereof

Abstract

The invention aims to solve the problem of abrasion of flow passage components of high sediment basin pump stations and hydropower stations. The preparation method comprises the following steps: mixing and cleaning WC, Cr, Co, Ti, Si, B, Re and Ni, heating and melting, cooling, preserving heat, carrying out inert gas high-pressure atomization, and cooling to room temperature to obtain atomized powder; carrying out subzero treatment on the atomized powder to obtain WC reinforced nickel-based powder; the WC reinforced nickel-based powder is screened and dried, and abrasion-resistant coating powder is obtained; and the WC particle reinforced nickel-based composite wear-resistant coating is prepared from the wear-resistant coating powder on a spraying substrate through a laser cladding process. Through design of powder components of the WC particle reinforced nickel-based composite wear-resistant coating and continuous exploration of a powder preparation process and a coating preparation process, the rare earth modified reinforced composite coating prepared by using a laser cladding method is compact and uniform, the porosity is below 0.4%, and the average microhardness is 1000-1330 HV0.2; and high abrasion resistance of the coating is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of overcurrent component coating preparation, and relates to a WC particle reinforced nickel-based composite anti-erosion coating powder and a preparation method thereof. BACKGROUND

[0002] Water turbines are widely used in the field of water power generation, but they face serious erosion problems during operation. The impact of sand particles carried by the water flow and cavitation will cause continuous wear and erosion to the turbine blades, runner and other components, greatly reducing the efficiency and service life of the turbine, increasing maintenance costs and downtime, and affecting the stable production of hydropower energy.

[0003] Traditional anti-erosion coating preparation methods have many limitations. For example, the coating prepared by thermal spraying process has relatively low bonding strength, and under the impact of high-speed water flow and complex working conditions of the turbine, the coating is easy to fall off and fail. The methods of electroplating and chemical plating have environmental problems, and the uniformity of the coating thickness is difficult to accurately control, and the adaptability to large-area and complex-shaped turbine components is poor. Laser cladding technology, as a new surface modification technology, has the advantages of high bonding strength between cladding layer and substrate, low dilution rate, and small heat-affected zone, and has great potential in the field of anti-erosion repair and strengthening of water turbines. The quality of the powder, as a key raw material for laser cladding, directly determines the performance of the cladding layer.

[0004] At present, common powder preparation methods such as gas atomization method are prone to introduce impurities when preparing anti-erosion powder for water turbines, and the particle size distribution of the powder is difficult to accurately control, affecting the density and uniformity of the laser cladding layer. Mechanical mixing method is difficult to achieve uniform dispersion of alloying elements, resulting in unstable performance of the cladding layer. Therefore, there is an urgent need for a new powder preparation method to meet the demand for high-quality anti-erosion powder for laser cladding of water turbines.

[0005] Vacuum gas atomization preparation technology can perform atomization operation in a vacuum environment, effectively reduce the introduction of impurities, accurately control the particle size and morphology of the powder, and realize uniform mixing and distribution of alloying elements, which is expected to prepare special powder for laser cladding of water turbines with excellent anti-erosion performance, high sphericity and controllable particle size, thereby providing a more reliable and efficient solution for anti-erosion protection of water turbines and promoting the stable development and technological progress of the hydropower industry. SUMMARY

[0006] The application aims to solve the problem of easy erosion of the coating on the overcurrent components of the pump station and hydropower station in the high-sediment flow area.

[0007] To solve the above problems, the application is implemented by the following technical scheme: A preparation method of a WC particle reinforced nickel-based composite anti-abrasion coating, comprising the following steps: S1, washing, melting, cooling, holding, inert gas high pressure atomization of WC, Cr, Co, Ti, Si, B, Re, Ni to obtain atomized powder; S2, cryogenic treatment of the atomized powder in step S1 to obtain WC reinforced nickel-based powder; S3, screening and drying of the WC reinforced nickel-based powder in step S2 to obtain anti-abrasion coating powder; S4, preparing a WC particle reinforced nickel-based composite anti-abrasion coating on a cleaned spraying substrate by laser cladding of the anti-abrasion coating powder in step S3.

[0008] The atomized powder in step S1 comprises the following components by mass percentage: WC content 20-40%; metal Cr content 10-15%; metal Co content 5-10%; metal Ti content 3-8%; Si content 0.8-1.2%; B content 0.4-0.6%; Re content 0.5-1.0%, and the balance is Ni.

[0009] The Re in step S1 is any one of CeO2 or La2O3.

[0010] The size of 20-35% of the WC powder in step S1 is 40-100 nm, and the size of the rest is 4-6 μm.

[0011] The melting temperature in step S1 is 1700-1800℃.

[0012] The cooling temperature in step S1 is 1550-1450℃, and the holding time is 20-40 min.

[0013] The inert gas in step S1 is argon, and the high pressure is 4.5-6.5 MPa.

[0014] The cryogenic treatment temperature in step S2 is -196 to -130℃, and the treatment time is 4-10 h.

[0015] The particle size of the screened powder in step S3 is 50-125 μm.

[0016] The power during laser cladding in step S4 is 1200-3000 W, the scanning speed is 5-10 mm / s, the powder feeding amount is 7-20 g / min, and the overlap rate is 40-60%.

[0017] Preferably, the cleaning agent for cleaning in step S1 is acetone or alcohol, and the cleaning time is 30-60 min. Preferably, the drying temperature in step S3 is 100-120℃, and the drying time is 1-2 h.

[0018] Preferably, the cleaning agent for cleaning the spraying substrate in step S4 is acetone or alcohol; and the cleaning time is 30-60 min. Compared with the prior art, the application has the following beneficial effects: 1. The application uses WC as a precursor of in-situ reaction instead of regarding WC as the final reinforcing phase. The application directly adds WC into the high-temperature melt, actively uses the controllable decomposition reaction of WC, and makes WC in a metastable state at a high temperature of >1600 DEG C in vacuum induction melting. The WC partially decomposes: WC→W+C. This is a metallurgical process of "decomposition-recombination". The decomposed W is dissolved in the nickel matrix to play a solid solution strengthening role. The decomposed C reacts with Ti and other elements to generate dispersed nanoscale TiC particles in-situ, which have a coherent or semi-coherent relationship with the matrix.

[0019] 2. The application realizes "micron-nanometer" dual-scale synergistic reinforcement. In the traditional coating structure design, only micron-sized WC particles are externally added. The application controls the melting temperature and time to control the decomposition of WC, so that micron-sized WC particles that are not completely dissolved and nanoscale TiC composite carbides generated in-situ are obtained in the microstructure of the final powder. The micron-sized WC particles serve as the main anti-wear framework and bear the macroscopic wear load. The nanoscale TiC composite carbides are dispersedly distributed in the matrix to produce strong dispersion strengthening and fine-grain strengthening effects, greatly improving the hardness and high-temperature strength of the matrix itself. The unique "micron-nanometer dual-scale reinforcement" structure enables the coating to have extremely high hardness and excellent toughness.

[0020] 3. The application provides a WC particle reinforced nickel-based composite anti-erosion coating powder, which comprises, in mass percentage: WC 20-40%; Cr 10-15%; Co 5-10%; Ti 3-8%; Si 0.8-1.2%; B 0.4-0.6%; Re 0.5-1%; and Ni balance. The WC particle reinforced nickel-based composite anti-erosion coating powder provided by the application improves the oxidation resistance and corrosion resistance of the powder material by introducing Cr elements. Co elements improve the wettability of the nickel matrix, promote densification, and improve toughness. The introduction of appropriate amounts of Si and B elements reduces the alloy melting point, improves the melt flowability, and enhances the wettability of the melt to the WC particles to avoid aggregation. The addition of rare earth elements effectively refines the alloy grains. The WC ceramic particles improve the anti-erosion performance of the coating.

[0021] 4. In the preparation process of this application, cryogenic treatment is introduced. Cryogenic treatment refines the internal grains of the powder, which synergistically improves the strength, hardness and toughness of the powder. At the same time, due to the rapid drop in material temperature caused by cryogenic treatment, the material shrinks, which releases and adjusts the residual stress inside the powder, reduces the deformation and cracking caused by the release of residual stress during subsequent use, and improves the processing and anti-abrasion performance of the powder.

[0022] 5. This invention, through continuous research on the design of WC particle-reinforced nickel-based composite wear-resistant coating powder components, powder preparation process, and coating preparation process, utilizes laser cladding to prepare a dense and uniform rare-earth modified reinforced composite coating with a porosity below 0.4% and an average microhardness of 1000~1350 HV. 0.2 Under the same preparation process and abrasion test parameters, the abrasion resistance of the coating is 2 to 4 times that of Stellite 6, achieving high abrasion resistance. Furthermore, the coating is crack-free under this process, and the composite coating preparation method is reliable and stable, making it suitable for application in abrasion and cavitation resistance fields such as water turbines and pumps. It is applicable to high-siltation flow environments, and is particularly suitable for use on flow-through components of hydraulic equipment such as water turbines and pumps. Attached Figure Description

[0023] Figure 1 This is a SEM image of a laser cladding coating produced by mechanical mixing and powder preparation. Figure 2 This is a SEM image of a laser cladding coating produced by vacuum atomization powder production. Figure 3 Images showing the flaw detection results of coatings under different processes; Figure 4 Images of samples with different coatings that have been abraded. Detailed Implementation

[0024] The technical solution of the present invention will be further described in detail below with reference to examples.

[0025] In this embodiment of the invention, the substrate for spraying can be Q345 steel. Alternatively, ZG06Cr13Ni5Mo steel, 45 steel, or 2205 stainless steel can also be used. Q345 steel will be used as an example below. Unless otherwise specified, the instruments used in the laser cladding process in the following embodiments and comparative examples are German LDF4000 semiconductor lasers; laserline brand.

[0026] Example 1 Step S1, WC particle reinforced nickel-based composite anti-erosion coating powder is proportioned according to the following component ratio of mass percentage: 20% WC powder (20% of which is 40-100 nm in size, and the rest is 4-6 μm in size); Cr 10%; Co 5%; Ti 5%; Si: 0.8%; B: 0.4%; La2O3: 0.5%, and Ni is the balance; Powder No. 2 is vacuum gas atomized. After the raw materials are cleaned and impurities are removed, they are placed in a vacuum gas atomization equipment melting crucible. The melting crucible is gradually heated to 1700℃ by adjusting the equipment. After the metal is completely melted, the temperature is lowered to 1500℃, and the temperature is maintained for 20 min. After the heat preservation is completed, the molten liquid is directly poured into a transfer package, and the transfer package is preheated to a constant temperature of 1300℃. The molten liquid enters the atomization chamber through the guide pipe, and the atomization gas pressure is 5.5 MPa. After atomization is completed, the atomized powder is obtained, Step S2, the atomized powder in the powder collection bucket of the gas atomization equipment is directly subjected to cryogenic treatment, the cryogenic temperature is -180~-140℃, and the cryogenic time is 6h. After the cryogenic treatment is completed, mechanical screening is performed to obtain the required 50-125 μm particle size powder. Thus, WC reinforced nickel-based powder No. 2 is obtained.

[0027] Step S3, the WC reinforced nickel-based powder No. 2 is placed in a drying box for drying, the drying temperature is 110℃, and the drying time is 1h. An anti-erosion coating powder is obtained. Step S4, the surface of the Q345 steel spraying substrate is cleaned with acetone or alcohol, and is placed in a heat preservation box for drying at 50-60℃ to remove surface oil stains and dirt. The laser cladding process of the anti-erosion coating powder is as follows: the laser power is 1500W, the scanning speed is 5mm / s, the powder feeding amount is 7g / min, and the overlap rate is 50%.

[0028] The porosity of the WC particle reinforced nickel-based composite anti-erosion coating is 0.25%, and the average microhardness is 1300 HV 0.2 , and the microstructure is shown in Figure 2 .

[0029] Example 2 Step S1, WC particle reinforced nickel-based composite anti-erosion coating powder is proportioned according to the following component ratio of mass percentage: 20% WC powder (20% of which is 40-100 nm in size, and the rest is 4-6 μm in size); Cr 10%; Co 5%; Ti 5%; Si: 0.8%; B: 0.4%; La2O3: 0.5%, and Ni is the balance; The raw materials are cleaned and impurities are removed, and then placed in a vacuum gas atomization equipment melting crucible. The melting crucible is gradually heated to 1700 DEG C through equipment adjustment, and then cooled to 1500 DEG C after the metal is completely melted, and kept for 20 min. After the heat preservation is completed, it is directly poured into a transfer package, and the transfer package is preheated to a constant temperature of 1300 DEG C. The molten liquid enters the atomization chamber through the guide pipe, and the atomization pressure is 5.5 MPa. After atomization, the atomized powder is obtained, Step S2, directly deep cooling treatment is carried out on the atomized powder in the powder collecting barrel of the gas atomization equipment, the deep cooling temperature is-180~-140 DEG C, and the deep cooling time is 6 h. After the deep cooling treatment is completed, mechanical screening is carried out to obtain the required 50-125 mu m particle size powder. Thus, the WC reinforced nickel-based powder is obtained.

[0030] Step S3, the WC reinforced nickel-based powder is placed in a drying box for drying, the drying temperature is 110 DEG C, and the drying time is 1 h. Thus, the wear-resistant coating powder is obtained. Step S4, the surface of the spraying substrate Q345 steel is cleaned with acetone or alcohol, and is placed in a heat preservation box for drying at 50-60 DEG C to remove the surface oil stains and dirt. The laser cladding process of the wear-resistant coating powder is as follows: the laser power is 1500 W, the scanning speed is 5 mm / s, the powder feeding amount is 10 g / min, and the overlap rate is 50%.

[0031] The WC particle reinforced nickel-based composite wear-resistant coating obtained is as shown in the powder 2 coating. Figure 3 The prepared powder 2 coating has no cracks.

[0032] Example 3 Step S1, the WC particle reinforced nickel-based composite wear-resistant coating powder is prepared according to the following component ratio: 20% WC powder (20% of which has a size of 40-100 nm, and the rest has a size of 4-6 mu m); Cr 10%; Co 5%; Ti 5%; Si: 0.8%; B: 0.4%; CeO2: 0.7%, and the rest is Ni. The raw materials are cleaned and impurities are removed, and then placed in a vacuum gas atomization equipment melting crucible. The melting crucible is gradually heated to 1700 DEG C through equipment adjustment, and then cooled to 1500 DEG C after the metal is completely melted, and kept for 20 min. After the heat preservation is completed, it is directly poured into a transfer package, and the transfer package is preheated to a constant temperature of 1300 DEG C. The molten liquid enters the atomization chamber through the guide pipe, and the atomization pressure is 5.5 MPa. After atomization, the atomized powder is obtained, Step S2, directly deep cooling treatment is carried out on the atomized powder in the powder collecting barrel of the gas atomization equipment, the deep cooling temperature is-180~-140 DEG C, and the deep cooling time is 6 h. After the deep cooling treatment is completed, mechanical screening is carried out to obtain the required 50-125 mu m particle size powder. Thus, the WC reinforced nickel-based powder is obtained.

[0033] Step S3, the WC reinforced nickel-based powder is put into a drying box for drying, the drying temperature is 110°C, and the drying time is 1h; an erosion-resistant coating powder is obtained; Step S4, the surface of the sprayed substrate Q345 steel is cleaned with acetone or alcohol, and is placed in a heat preservation box for drying at 50-60°C to remove the surface oil stains and dirt; The laser cladding process for obtaining the erosion-resistant coating powder is as follows: the laser power is 1500W, the scanning speed is 5mm / s, the powder feeding amount is 7g / min, and the overlap rate is 50%.

[0034] The porosity of the WC particle reinforced nickel-based composite erosion-resistant coating obtained is 0.32%, and the average microhardness is 1330HV 0.2 , and the erosion weight loss of the composite coating is 0.01423g.

[0035] The erosion conditions are as follows: after the cladding, the large sample is cut into a sample with a length of 18.8mm, a width of 18.8mm and a same thickness by wire cutting, the test sample is polished into a mirror surface effect by grinding with 180-2000 mesh sandpaper, and is placed in an ultrasonic cleaner for cleaning for 20min after grinding, and is dried and weighed. 10% of the area of the sample is clamped on the sample fixing disc, and the sand-water ratio is set to 40%. The test time period is 12 hours for measuring the weight loss. The sand grain size is 40-80 mesh.

[0036] Comparative Example 1 The other conditions are completely same as those in Example 1, and the difference is that: Step S1, the powder 1 is not prepared by vacuum gas atomization, and the powder 1 is prepared by mechanical mixing at a stirring speed of 13rpm for 24h, and the particle size of the prepared powder is 50-125μm.

[0037] The porosity of the composite coating prepared by the powder 1 is 0.75%, and the average microhardness is 1100HV 0.2 , and the microstructure is as shown in Figure 1 .

[0038] Comparative Example 2 The other conditions are completely same as those in Example 2, and the difference is that: Step S4, the laser cladding process for the erosion-resistant coating powder is as follows: the laser power is 500W, the scanning speed is 5mm / s, the powder feeding amount is 10g / min, and the overlap rate is 50%.

[0039] The flaw detection of the prepared WC particle reinforced nickel-based composite erosion-resistant coating is as shown in Figure 3 , and the powder 1 coating appears cracking phenomenon.

[0040] Comparative Example 3 Other conditions are exactly the same as example 2, compared with example 2, the difference is that, The laser cladding process of the anti-abrasion coating powder in step S4 is: laser power 1500W, scanning speed 3mm / s; powder feeding amount 10g / min; overlap rate 50%.

[0041] The flaw detection of the prepared WC particle reinforced nickel-based composite anti-abrasion coating is as shown in Figure 3 The powder 3 coating appears cracking phenomenon.

[0042] Comparative example 4 Other conditions are exactly the same as example 2, compared with example 2, the difference is that, The laser cladding process of the anti-abrasion coating powder in step S4 is: laser power 1500W, scanning speed 5mm / s; powder feeding amount 30g / min; overlap rate 50%.

[0043] The flaw detection of the prepared WC particle reinforced nickel-based composite anti-abrasion coating is as shown in Figure 3 The powder 4 coating appears cracking phenomenon.

[0044] Comparative example 5 Other conditions are exactly the same as example 3, compared with example 3, the difference is that: The WC particle reinforced nickel-based composite anti-abrasion coating powder in step S1 is replaced by Stellite 6 (Stellite6); Stellite 6 (Stellite6) is a purchased finished powder, the powder particle size is 50-125μm, and the specific components (in mass percentage) are: carbon C: 1.3; Ni: 2; W: 4.5; Si: 0.8; Mn: 0.5; Mo: 1; Fe: 2; Cr: 29.7; Co: balance.

[0045] The porosity of the Stellite 6 (Stellite6) coating is 0.36%, and the average microhardness is 532 HV 0.2 . The abrasion weight loss of the Stellite 6 coating is: 0.04212g.

[0046] From example 3 and comparative example 5, it can be seen that under the same abrasion conditions, the anti-abrasion performance of the prepared composite coating is 2.96 times that of Stellite 6 (Stellite6) under the same process conditions.

[0047] The comparison of Stellite 6 and the coating sample of the present example 3 is shown in Figure 4 .

Claims

1. A method of producing a WC particle reinforced nickel-based composite erosion resistant coating, characterized in that, The method comprises the following steps: S1, cleaning, melting, cooling, holding, inert gas high pressure atomization of WC, Cr, Co, Ti, Si, B, Re, Ni to obtain atomized powder; S2, cryogenic treatment of the atomized powder in step S1 to obtain WC reinforced nickel-based powder; S3, screening and drying of the WC reinforced nickel-based powder in step S2 to obtain an anti-erosion coating powder; S4, laser cladding of the anti-erosion coating powder in step S3 on a cleaned spraying substrate to obtain a WC particle reinforced nickel-based composite anti-erosion coating.

2. The method of claim 1, wherein the WC particle reinforced nickel-based composite anti-erosion coating is prepared by the following steps: (1) preparing a WC particle reinforced nickel-based composite coating precursor; (2) sintering the WC particle reinforced nickel-based composite coating precursor to obtain the WC particle reinforced nickel-based composite anti-erosion coating. The atomized powder in step S1 comprises the following components by mass percentage: WC content 20-40%; metal Cr content 10-15%; metal Co content 5-10%; metal Ti content 3-8%; Si content 0.8-1.2%; B content 0.4-0.6%; Re content 0.5-1.0%, and the balance is Ni.

3. The method of claim 1, wherein the WC particle reinforced nickel-based composite anti-erosion coating is prepared by the following steps: (1) preparing a WC particle reinforced nickel-based composite coating precursor; (2) sintering the WC particle reinforced nickel-based composite coating precursor to obtain the WC particle reinforced nickel-based composite anti-erosion coating. The Re in step S1 is any one of CeO2 or La2O3.

4. The method for preparing a WC particle-reinforced nickel-based composite wear-resistant coating according to claim 1, characterized in that, The size of 20-35% of the WC powder in step S1 is 40-100 nm, and the size of the rest is 4-6 μm.

5. The method for preparing a WC particle-reinforced nickel-based composite wear-resistant coating according to claim 1, characterized in that, The melting temperature in step S1 is 1700-1800℃.

6. The method of claim 1, wherein the WC particle reinforced nickel-based composite anti-erosion coating is prepared by the steps of: The cooling temperature in step S1 is 1550-1450℃, and the holding time is 20-40 min.

7. The method for preparing a WC particle-reinforced nickel-based composite wear-resistant coating according to claim 1, characterized in that, The inert gas in step S1 is argon, and the high pressure is 4.5-6.5 MPa.

8. The method of claim 1, wherein the WC particle reinforced nickel-based composite anti-erosion coating is prepared by the steps of: The cryogenic treatment temperature in step S2 is -196 to -130℃, and the treatment time is 4-10 h.

9. The method of claim 1, wherein the WC particle reinforced nickel-based composite erosion resistant coating is prepared by a process comprising: The particle size of the screened powder in step S3 is 50-125 μm.

10. The method of claim 1, wherein the WC particle reinforced nickel-based composite erosion resistant coating is prepared by a process comprising: The power during laser cladding in step S4 is 1200-3000 W, the scanning speed is 5-10 mm / s, the powder feeding amount is 7-20 g / min, and the overlap rate is 40-60%.

Images