A method for preparing a diamond-ni-based corrosion-resistant coating by supersonic spraying / remelting

Abstract

The invention discloses a diamond-Ni-based corrosion-resistant coating supersonic spraying / remelting preparation method, which belongs to the technical field of wear-resistant coating preparation, and comprises the following steps: powder weighing, Cr-plated diamond preparation, supersonic spraying wear-resistant coating preparation, high-frequency induction remelting treatment, salt spray corrosion test and the like. The invention combines the supersonic spraying and high-frequency induction processes, and is a diamond corrosion-resistant coating preparation scheme specially designed for strengthening material properties. The combined process not only deepens the understanding of material properties, but also realizes breakthroughs in the actual operation level, and provides solutions for many industries which depend on high-strength and high-wear-resistant surface treatment.

Description

Technical Field

[0001] This invention belongs to the field of corrosion-resistant coating preparation technology. Specifically, it uses gas-atomized NiCrBSi (Ni45) alloy powder as coating master powder and Cr-plated diamond as corrosion-resistant additive phase to prepare functionalized coating composite powder. The composite powder is sprayed onto the surface of metal parts using a combination of supersonic spraying and high-frequency induction remelting technology to prepare a diamond-containing corrosion-resistant coating. Background Technology

[0002] Corrosion and wear are the main failure modes of metal components, and improving the corrosion resistance of metal components has always been a major concern and a problem that needs to be solved in the engineering industry. To improve the surface structure of materials, technologies such as supersonic spraying and laser cladding are often used in engineering to apply a protective coating with higher corrosion resistance than the component substrate to the surface of metal components, thereby improving their corrosion resistance. Supersonic spraying involves igniting gas in a high-temperature, high-pressure combustion chamber to generate a high-temperature, high-speed gas flow. This high-temperature, high-speed gas flow locally melts powder particles and sprays them onto the substrate surface, forming an adherent coating. Using supersonic spraying technology to apply corrosion-resistant coatings of metal / ceramic materials to the surface of metal components has become a common method in surface protection engineering. However, supersonic spraying coatings still suffer from low powder application rates and weak interfacial bonding between coating powder particles, which greatly affects the quality and performance of the coating. At the same time, the existing corrosion resistance of metal materials still cannot meet the requirements of metal components operating in extremely harsh environments, necessitating the development of new corrosion-resistant materials. Therefore, this invention uses a combination of supersonic spraying and high-frequency induction remelting technology to improve the coating's density, microstructure, and corrosion resistance. Ni45 is a common wear-resistant / corrosion-resistant material, but its supersonic spray coating also suffers from drawbacks such as uneven coating thickness, weak interfacial bonding between powder particles, and insufficient corrosion resistance. The literature "Study on Microstructure and Wear and Corrosion Resistance of Arc-Sprayed Ni-Based Alloy Coatings" ([J / OL]. Hot Working Technology, 1-7 [2024-10-17].) studied the corrosion resistance behavior of Ni-Al and Ni-Cu alloy coatings, finding that the Ni-Al alloy coating has slightly higher hardness and slightly higher wear resistance than the Ni-Cu alloy coating; while the Ni-Cu coating has higher corrosion resistance than the Ni-Al coating, significantly improving the corrosion resistance of the substrate in simulated seawater. Therefore, it is evident that none of the coatings in the literature can simultaneously meet the requirements of wear resistance and corrosion resistance. Thus, researching and developing a functional coating that combines good wear resistance and corrosion resistance is a practical need in the engineering field. Diamond is a very stable material with extremely high hardness and chemical stability. Because it is composed of carbon atoms arranged in sp... 3 The tetrahedral structure formed by the hybrid orbitals is closely arranged, sp 3High bond energy provides excellent corrosion resistance to most acids, alkalis, and other chemicals. Combining diamond with Ni45 alloy powder to prepare corrosion-resistant / wear-resistant coatings can simultaneously improve both corrosion and wear resistance. However, due to the strong chemical inertness of the diamond surface, it is difficult to achieve metallurgical bonding with the metal substrate, leading to easy detachment and failure of the coating, thus affecting its corrosion resistance. To address these challenges, this invention uses Ni45 alloy powder as the coating master powder and Cr-plated diamond as the corrosion-resistant reinforcing phase. A combination of supersonic spraying and high-frequency induction remelting technology is employed. First, a supersonic sprayed coating is prepared, followed by high-frequency induction remelting. Salt spray corrosion tests show that adding diamond to the Ni-based coating effectively improves its corrosion resistance. Summary of the Invention

[0003] To overcome the aforementioned shortcomings and improve the corrosion resistance of supersonic sprayed coatings, this invention provides a process for preparing diamond-Ni-based metal corrosion-resistant coatings using a supersonic spraying / remelting combination technology. Cr-plated diamond and Ni45 are mixed at a mass ratio of 10%-50% as a functionalized coating material. A corrosion-resistant coating with a thickness of 100μm-200μm is prepared on the surface of a metal component using supersonic spraying technology. The coating is then remelted using high-frequency induction technology to prepare a dense, corrosion-resistant coating with Cr-plated diamond as the reinforcing phase, where diamond can form a good interfacial metallurgical bond with the base metal.

[0004] The specific technical solution of the present invention is as follows:

[0005] A method for preparing a diamond-Ni-based corrosion-resistant coating by supersonic spraying / remelting includes the following steps:

[0006] 1) Preparation of Cr-plated diamond: Diamond micro powder with a particle size of 10-100μm is used to plate metallic Cr onto the diamond surface using a combination of physical and chemical plating methods to obtain Cr-plated diamond; the thickness of the Cr plating layer is 0.1-2μm;

[0007] 2) Preparation of functionalized coating powder: Prepare powder by mixing commercially available air-atomized Ni45 alloy powder with a particle size of 140-325 mesh at a mass ratio of 10%-50% Cr-plated diamond. Mix the powder in a three-dimensional mixer for 60 minutes to obtain functionalized mixed spray powder. Place the mixed powder in a vacuum oven and dry it at 100°C and a vacuum degree of 10. -1 Dry under Pa conditions for 2 hours, then vacuum-seal after natural cooling for later use.

[0008] 3) Preparation of corrosion-resistant coating by supersonic spraying: Before spraying, the steel plate substrate is sandblasted to remove rust and increase its roughness, which helps to improve the mechanical bonding strength between the coating and the substrate. Then, supersonic spraying is performed on the sandblasted steel plate substrate surface. The spraying parameters are: powder feed rate 5-8 kg / h, oxygen flow rate 11.6 Nm³ / h. 3 / h, oxygen pressure 2.0MPa, fuel flow rate 8.5Nm 3 / h, carrier gas flow rate 10Nm 3 / h, spraying distance 300-360mm, 10-20 layers;

[0009] 4) High-frequency induction remelting of coating: First, fabricate an induction coil to ensure that the coil can accurately cover the area to be treated. Second, finely adjust the distance between the coil and the workpiece to ensure that the induction heating area can effectively cover the interface between the coating and the steel plate substrate. Then, perform high-frequency induction remelting. The process parameters are: power 700-1100W, distance between the induction coil and the workpiece surface 1-3cm, remelting time 20-30s, working protective gas is nitrogen, nitrogen flow rate 0.2L / min.

[0010] 5) Salt spray corrosion test: The workpiece after plasma spraying / high-frequency induction remelting is cut into 10mm×15mm samples. The non-sprayed surfaces are sealed with a high-polymer corrosion-resistant material for corrosion resistance. Then, the samples are subjected to a salt spray corrosion test (neutral salt spray test). The salt spray corrosion conditions are set as follows: saturator temperature 35-50℃, pH value 6.5-7.2, continuous spraying of the medium salt solution, relative humidity in the test chamber 94±4%, and air source pressure 8kg / cm². 2 The inlet pressure was 0.2-0.4 MPa, the spray pressure was 0.07-0.15 MPa, and the experimental cycle was 200-1000 hours.

[0011] Preferably, the diamond micro powder in step 1) has a particle size of 10-15 μm and the Cr coating thickness is 1-2 μm.

[0012] Preferably, the Ni45 alloy powder composition in step 2) has the following weight ratio: Cr 27%, Si 8%, Fe 4%-7%, B 4.5%, C 0.9%-1.2%, with the balance being Ni; the mass ratio of Ni45 alloy powder to Cr-plated diamond powder is 9:1.

[0013] Preferably, in step 3), the powder feeding speed of the supersonic spraying is 6 kg / h, the spraying distance is 340 mm, and the number of spraying times is 15.

[0014] Preferably, in step 4), the power of high-frequency induction remelting is 1000W, the distance between the induction coil and the workpiece surface is 1cm, and the remelting time is 25s.

[0015] Preferably, the saturator temperature for step 5) of the salt spray corrosion test is 35℃, pH value is 6.7, inlet pressure is 0.2MPa, spray pressure is 0.1MPa, and the test cycle is 500h.

[0016] Beneficial effects:

[0017] 1. This invention combines Cr-plated diamond with atomized Ni45 alloy powder as a functionalized corrosion-resistant spraying material, and uses supersonic spraying technology to prepare a diamond-Ni-based corrosion-resistant coating, utilizing the super corrosion resistance of diamond to improve the corrosion resistance of the coating.

[0018] 2. This invention combines supersonic spraying and high-frequency induction remelting processes to prepare a corrosion-resistant coating. This strengthens the interfacial metallurgical bonding between heterogeneous powder particles and between the coating and the steel substrate, effectively increasing the coating's density and improving its microstructure and corrosion resistance. Supersonic sprayed coatings have high porosity and insufficient density, affecting their overall corrosion resistance. High-frequency induction remelting of the supersonic coating re-melts the sprayed coating, allowing the liquid molten phase to further fill the pores, improving the coating's density and uniformity, and enhancing its overall mechanical properties. Simultaneously, the remelting process strengthens the interfacial bond between the coating and the substrate, reducing the risk of delamination or peeling caused by thermal stress, thereby extending the coating's service life. Attached Figure Description

[0019] Figure 1 XRD pattern of the supersonic spray coating of Example 1.

[0020] Figure 2 SEM image of the surface morphology of the supersonic spray coating in Example 1.

[0021] Figure 3 XRD pattern of the supersonic spray coating after salt spray corrosion in Example 1.

[0022] Figure 4 SEM image of the surface morphology of the supersonic spray coating after salt spray corrosion in Example 1.

[0023] Figure 5 XRD pattern of the high-frequency induction remelting coating of Example 1.

[0024] Figure 6 SEM image of the surface morphology of the high-frequency induction remelting coating in Example 1.

[0025] Figure 7 XRD pattern of the high-frequency induction remelting coating after salt spray corrosion in Example 1.

[0026] Figure 8SEM image of the surface morphology of the high-frequency induction remelting coating after salt spray corrosion in Example 1. Detailed implementation method:

[0027] Example 1

[0028] 1) Preparation of Cr-plated diamond: Cr is plated onto 10-15μm diamond using a combination of physical and chemical plating methods. The weight gain of Cr plating is 50% of the weight of diamond micro powder. After plating, the Cr-plated diamond is repeatedly soaked and cleaned with deionized water. Then, the Cr-plated diamond after water washing is placed in an alcohol solution and ultrasonically treated for 15 minutes. After that, the diamond is placed in a vacuum drying oven and dried at room temperature.

[0029] 2) Preparation of spray powder: Ni45 alloy powder and diamond micro powder are weighed and prepared at a weight ratio of 9:1. Weigh 900g of atomized Ni45 alloy powder with a particle size of 140-325 mesh and weigh 100g of Cr-plated diamond with a particle size of 10-15μm. Put the two into a three-dimensional mixer and mix for 60min. After mixing, remove the powder and vacuum seal it for storage.

[0030] 3) Preparation of corrosion-resistant coating by supersonic spraying: Low-carbon steel with substrate dimensions of 200mm × 50mm × 5mm is selected. The substrate surface undergoes pretreatment such as sandblasting for rust removal / roughening. The mixed powder is placed into the supersonic spraying powder container. Process parameters are set as follows: powder feeding rate 6kg / h, oxygen flow rate 11.6Nm³. 3 / h, oxygen pressure 2.0MPa, fuel flow rate 8.5Nm 3 / h, carrier gas flow rate 10.0Nm 3 / h, spraying distance 320mm, 15 layers of spraying.

[0031] 4) High-frequency induction remelting treatment: Place the sprayed sample in a high-frequency induction device. The remelting parameters are: power 1000W, distance between the induction coil and the workpiece surface 1cm, remelting time 25s, working gas is nitrogen, and nitrogen flow rate is 0.2L / min.

[0032] 5) Set salt spray corrosion conditions: saturator temperature 35℃, pH value 6.7, continuous spraying method, relative humidity 94±4%, air source 8kg / cm³. 2 The inlet pressure was 0.2 MPa, the spray pressure was 0.1 MPa, and the experimental period was 500 hours.

[0033] In this embodiment, the porosity of the supersonic sprayed coating was 2.23%, and the porosity of the remelted coating was 1.17%, representing a reduction of approximately 48% in porosity compared to before remelting. The initial weight of the supersonic sprayed coating was 7.093 g, and the weight after corrosion was 7.045 g, a difference of 0.048 g. The weight of the remelted coating before corrosion was 6.558 g, and the weight after corrosion was 6.536 g, a difference of 0.022 g. The corrosion resistance after remelting was approximately 2.2 times higher than before remelting.

[0034] Figure 1 The XRD pattern of the supersonic sprayed coating reveals that the strong diffraction peaks correspond to solid solutions of Ni and diamond, indicating that diamond is effectively and completely retained in the coating. During the spraying process, the high-temperature heat source promotes the chemical reaction between Ni, Si, and B. The borides (Ni3B) and silicides (Ni3Si) appearing in the coating typically possess high hardness and good heat resistance, which enhances the coating's corrosion resistance and high-temperature performance. Simultaneously, phases such as CrB and Cr7C3 are also formed.

[0035] Figure 2 The SEM image of the supersonic spray coating shows that the powder particles on the surface of the coating are arranged in a raised pattern, the coating thickness is uneven, but there are few pores and cracks, and the coating quality is relatively good.

[0036] Figure 3 The image shows the XRD pattern of the supersonic sprayed coating after salt spray corrosion. The main phases on the coating surface are: NiO, Cr2O3, Ni2O3, and CrC. l3 and NiC l2 The oxides NiO, Cr2O3, and Ni2O3 are formed during the corrosion process by the reaction of Ni and Cr, which have strong oxidation resistance in the original sample, with oxygen.

[0037] Figure 4 The image shows the SEM morphology of the supersonic sprayed coating after salt spray corrosion. It reveals that the porosity of the coating further intensifies after corrosion. New slag-like oxides or chlorides form on the coating surface. This newly formed corrosion shell has a relatively dense and smooth structure, providing some protection to the covered area and slowing down the corrosion rate of the internal structure. However, as corrosion progresses, numerous porous structures appear beneath this corrosion shell, and some areas detach, exposing the inner coating. Corrosion continues at these exposed locations, and cracks appear in parts of the corrosion layer.

[0038] Figure 5The image shows the XRD pattern of the high-frequency induction remelting coating. It can be seen that the phase structure of the coating changes after high-frequency induction remelting treatment. Some of the Ni in the solid solution reacts with B to regenerate Ni4B3; some of the Si reacts with C to form the SiC phase.

[0039] Figure 6 The image shows the surface SEM morphology of the high-frequency induction remelting coating. It can be seen that after high-frequency induction remelting, the coating thickness is more uniform, the coating becomes smoother and more even, the number of pores and cracks is reduced, the microstructure of the coating is improved, and the microstructure properties are enhanced.

[0040] Figure 7 The image shows the XRD pattern of the high-frequency induction remelting coating after salt spray corrosion. The coating also contains the corresponding oxides and chlorides of Cr and Ni, but the peak intensities of these compounds are reduced compared to before.

[0041] Figure 8 The image shows the surface SEM morphology of the high-frequency induction remelted coating after salt spray corrosion. It can be observed that the surface of the remelted sample has good density and continuity, and the apparent corrosion area is reduced. The mass change of the sample before and after corrosion is small, indicating that the corrosion resistance of the coating is enhanced.

[0042] Example 2

[0043] Preparation of corrosion-resistant coating by supersonic spraying: The mixed powder from Example 1 was placed into a supersonic spraying device, and the spraying process parameters were changed: powder feed rate 6 kg / h, oxygen flow rate 10.0 Nm³ / h. 3 / h, oxygen pressure 2.2MPa, fuel flow rate 8.0Nm 3 / h, carrier gas flow rate 10.0Nm 3 / h, spraying distance 340mm, 12 layers of spraying.

[0044] High-frequency induction remelting treatment: The sprayed sample is placed in a high-frequency induction device. The remelting parameters are: power 1000W, distance between the induction coil and the workpiece surface 1cm, remelting time 22s, working gas is nitrogen, and nitrogen flow rate is 0.3L / min.

[0045] The salt spray corrosion conditions were modified as follows: saturator temperature 40℃, pH value 7, continuous spraying of the corrosive salt solution, relative humidity in the sample chamber 94±4%, and air source 8kg / cm³. 2 The inlet pressure was 0.3 MPa, the spray pressure was 0.13 MPa, and the experimental period was 500 hours.

[0046] In this example, the porosity of the supersonic sprayed coating was 2.73%, and the porosity of the remelted coating was 1.39%, representing a decrease of approximately 49% in porosity. The weight of the supersonic sprayed coating before corrosion was 8.266 g, and the weight after corrosion was 8.221 g, a difference of 0.045 g. The weight of the remelted coating before corrosion was 7.258 g, and the weight after corrosion was 7.231 g, a difference of 0.027 g. Therefore, comparing the weight loss of the samples before and after corrosion shows that the corrosion resistance of the remelted sample was improved by approximately 40% compared to before remelting.

[0047] Example 3

[0048] Preparation of corrosion-resistant coating by supersonic spraying: The mixed powder from Example 1 was placed into a supersonic spraying device, and the spraying process parameters were changed: powder feed rate 5.5 kg / h, oxygen flow rate 12.0 Nm³ / h. 3 / h, oxygen pressure 2.0MPa, fuel flow rate 9.0Nm 3 / h, carrier gas flow rate 11.0Nm 3 / h, spraying distance 360mm, 15 layers of spraying.

[0049] High-frequency induction remelting treatment: The sprayed sample is placed in a high-frequency induction device. The remelting parameters are: power 900W, distance between the induction coil and the workpiece surface 1.1cm, remelting time 25s, working gas is nitrogen, and nitrogen flow rate is 0.2L / min.

[0050] Modified salt spray corrosion conditions: saturator temperature 38℃, pH value 7.1, continuous spraying method, relative humidity 94±4%, air source 8kg / cm³. 2 The inlet pressure was 0.4 MPa, the spray pressure was 0.15 MPa, and the experimental period was 500 hours.

[0051] In this example, the porosity of the supersonic sprayed coating was 2.03%, and the porosity of the remelted coating was 1.22%, representing a decrease of approximately 39% in porosity compared to before remelting. The weight of the supersonic sprayed coating before corrosion was 9.511 g, and the weight after corrosion was 9.465 g, a difference of 0.046 g. The weight of the remelted coating before corrosion was 7.144 g, and the weight after corrosion was 7.110 g, a difference of 0.034 g. The corrosion resistance of the remelted sample improved by approximately 26% compared to before remelting.

[0052] Example 4

[0053] Coating powder preparation: Change the weight ratio of Ni45 alloy powder to diamond micro powder to 8:2. Weigh 800g of atomized Ni45 alloy powder with a particle size of 140-325 mesh, weigh 200g of Cr-plated diamond with a particle size of 10-15μm, put the two into a three-dimensional mixer and mix for 60min. After mixing, take it out for later use.

[0054] Preparation of corrosion-resistant coating by supersonic spraying: The mixed powder is placed into a supersonic spraying device with a powder feeding rate of 6 kg / h and an oxygen flow rate of 11.6 Nm³. 3 / h, oxygen pressure 2.0MPa, fuel flow rate 8.5Nm 3 / h, carrier gas flow rate 10.0Nm 3 / h, spraying distance 340mm, 15 layers of spraying.

[0055] High-frequency induction remelting treatment: The sprayed sample is placed in a high-frequency induction device. The remelting parameters are: power 1000W, distance between the induction coil and the workpiece surface 1cm, remelting time 25s, working gas is nitrogen, and nitrogen flow rate is 0.2L / min.

[0056] Change the salt spray corrosion conditions: saturator temperature 35℃, pH value 6.5, continuous spraying method, relative humidity 94±4%, air source 8kg / cm³. 2 The inlet pressure was 0.2 MPa, the spray pressure was 0.08 MPa, and the experimental period was 500 hours.

[0057] In this example, the porosity of the supersonic sprayed coating was 2.53%, and the porosity of the remelted coating was 1.37%, representing a decrease of approximately 46% in porosity compared to before remelting. The weight of the supersonic sprayed coating before corrosion was 7.298 g, and the weight after corrosion was 7.245 g, a difference of 0.053 g. The weight of the remelted coating before corrosion was 8.949 g, and the weight after corrosion was 8.913 g, a difference of 0.036 g. The comparative results show that the corrosion resistance of the remelted sample was improved by approximately 32% compared to before remelting.

[0058] Example 5

[0059] Coating powder preparation: Change the weight ratio of Ni45 alloy powder to diamond micro powder to 7:3. Weigh 700g of atomized Ni45 alloy powder with a particle size of 140-325 mesh, weigh 300g of Cr-plated diamond with a particle size of 10-15μm, put the two into a three-dimensional mixer and mix for 60min. After mixing, take it out for later use.

[0060] Preparation of corrosion-resistant coating by supersonic spraying: The mixed powder is placed into a supersonic spraying device, and the process parameters are set as follows: powder feeding speed 6 kg / h, oxygen flow rate 11.6 Nm³ / h.3 / h, oxygen pressure 2.0MPa, fuel flow rate 8.5Nm 3 / h, carrier gas flow rate 10.0Nm 3 / h, spraying distance 340mm, 15 layers of spraying.

[0061] High-frequency induction remelting treatment: The sprayed sample is placed in a high-frequency induction device. The remelting parameters are: power 1000W, distance between the induction coil and the workpiece surface 1cm, remelting time 25s, working gas is nitrogen, and nitrogen flow rate is 0.2L / min.

[0062] Modify salt spray corrosion conditions: saturator temperature 50℃, pH value 6.8, continuous spraying of salt solution, relative humidity 94±4%, air source 8kg / cm³. 2 The inlet pressure was 0.25 MPa, the spray pressure was 0.14 MPa, and the experimental period was 500 hours.

[0063] In this example, the porosity of the supersonic sprayed coating was 2.79%, and the porosity of the remelted coating was 1.56%, representing a decrease of approximately 44% in porosity compared to before remelting. The weight of the supersonic sprayed coating before corrosion was 7.295 g, and the weight after corrosion was 7.237 g, a difference of 0.058 g. The weight of the remelted coating before corrosion was 6.574 g, and the weight after corrosion was 6.541 g, a difference of 0.033 g. The comparative results show that the corrosion resistance of the remelted sample was improved by approximately 43% compared to before remelting.

[0064] Example 6

[0065] Coating powder preparation: Change the weight ratio of Ni45 alloy powder to diamond micro powder to 5:5. Weigh 500g of atomized Ni45 alloy powder with a particle size of 140-325 mesh, weigh 500g of Cr-plated diamond with a particle size of 10-15μm, put the two into a three-dimensional mixer and mix for 60min. After mixing, take it out for later use.

[0066] Preparation of corrosion-resistant coating by supersonic spraying: The mixed powder is placed into a supersonic spraying device, and the process parameters are set as follows: powder feeding speed 6 kg / h, oxygen flow rate 11.6 Nm³ / h. 3 / h, oxygen pressure 2.0MPa, fuel flow rate 8.5Nm 3 / h, carrier gas flow rate 10.0Nm 3 / h, spraying distance 340mm, 15 layers of spraying.

[0067] High-frequency induction remelting treatment: The sprayed sample is placed in a high-frequency induction device. The remelting parameters are: power 1000W, distance between the induction coil and the workpiece surface 1cm, remelting time 25s, working gas is nitrogen, and nitrogen flow rate is 0.2L / min.

[0068] Modify salt spray corrosion conditions: saturator temperature 44℃, pH 7.0, continuous spraying of salt solution, relative humidity 94±4%, air source 8kg / cm³. 2 The inlet pressure was 0.4 MPa, the spray pressure was 0.09 MPa, and the experimental period was 500 hours.

[0069] In this example, the porosity of the supersonic sprayed coating was 3.22%, and the porosity of the remelted coating was 2.05%, representing a decrease of approximately 36% in porosity compared to before remelting. The weight of the supersonic sprayed coating before corrosion was 7.249 g, and the weight after corrosion was 7.205 g, a difference of 0.044 g. The weight of the remelted coating before corrosion was 9.400 g, and the weight after corrosion was 9.375 g, a difference of 0.025 g. The comparative results show that the corrosion resistance of the remelted sample was improved by approximately 43% compared to before remelting.

Claims

1. A method for preparing a diamond-Ni-based corrosion-resistant coating by supersonic spraying / remelting, comprising the following steps: 1) Preparation of Cr-plated diamond: Diamond micro powder with a particle size of 10-100μm is used to plate metallic Cr on the diamond surface using a combination of physical and chemical plating methods to obtain Cr-plated diamond; the thickness of the Cr plating layer is 0.1-2 µm. 2) Preparation of functionalized coating powder: Prepare powder by mixing commercially available gas-atomized Ni45 alloy powder with a particle size of 140-325 mesh at a mass ratio of 10%-50% Cr-plated diamond. Mix the powder in a three-dimensional mixer for 60 min to obtain functionalized mixed spray powder. Place the mixed powder in a vacuum oven and dry it at 100 ℃ and a vacuum degree of 10. -1 Dry under Pa conditions for 2 hours, then vacuum-seal after natural cooling for later use. 3) Preparation of corrosion-resistant coating by supersonic spraying: Before spraying, the steel plate substrate is sandblasted to remove rust and increase its roughness, which helps to improve the mechanical bonding strength between the coating and the substrate. Then, supersonic spraying is performed on the sandblasted steel plate substrate surface. The spraying parameters are: powder feed rate 5-8 kg / h, oxygen flow rate 11.6 Nm³. 3 / h, oxygen pressure 2.0MPa, fuel flow rate 8.5 Nm 3 / h, carrier gas flow rate 10 Nm 3 / h, spraying distance 300-360 mm, 10-20 layers; 4) High-frequency induction remelting of coating: First, fabricate an induction coil to ensure that the coil can accurately cover the area to be treated. Second, finely adjust the distance between the coil and the workpiece to ensure that the induction heating area can effectively cover the interface between the coating and the steel plate substrate. Then, perform high-frequency induction remelting. The process parameters are: power 700-1100 W, distance between the induction coil and the workpiece surface 1-3 cm, remelting time 20-30 s, working protective gas is nitrogen, nitrogen flow rate 0.2 L / min. 5) Salt spray corrosion test: The workpiece after supersonic spraying / high-frequency induction remelting is cut into 10mm×15mm samples. The non-sprayed surfaces are treated with a high-polymer corrosion-resistant material for corrosion protection. Then, the samples are subjected to a salt spray corrosion test. The salt spray corrosion conditions are set as follows: saturator temperature 35-50℃, pH value 6.5-7.2, continuous spraying of salt solution, relative humidity in the test chamber 94±4%, and air source pressure 8 kg / cm². 2 The inlet pressure was 0.2-0.4 MPa, the spray pressure was 0.07-0.15 MPa, and the experimental cycle was 200-1000 h.

2. The method for preparing a diamond-Ni-based corrosion-resistant coating by supersonic spraying / remelting according to claim 1, characterized in that, The diamond micro powder mentioned in step 1) has a particle size of 10-15 μm and a Cr coating thickness of 1-2 μm.

3. The method for preparing a diamond-Ni-based corrosion-resistant coating by supersonic spraying / remelting according to claim 1, characterized in that, The Ni45 alloy powder composition in step 2) has the following weight ratio: Cr 27%, Si 8%, Fe 4%-7%, B 4.5%, C 0.9%-1.2%, with the balance being Ni; the mass ratio of Ni45 alloy powder to Cr-plated diamond powder is 9:

1.

4. The method for preparing a diamond-Ni-based corrosion-resistant coating by supersonic spraying / remelting according to claim 1, characterized in that, In step 3), the powder feeding speed of supersonic spraying is 6 kg / h, the spraying distance is 340 mm, and the number of spraying times is 15.

5. The method for preparing a diamond-Ni-based corrosion-resistant coating by supersonic spraying / remelting according to claim 1, characterized in that, Step 4) The power of high-frequency induction remelting is 1000 W, the distance between the induction coil and the workpiece surface is 1 cm, and the remelting time is 25 s.

6. The method for preparing a diamond-Ni-based corrosion-resistant coating by supersonic spraying / remelting according to claim 1, characterized in that, Step 5) The saturator temperature for the salt spray corrosion test was 35℃, pH value was 6.7, inlet pressure was 0.2 MPa, spray pressure was 0.1 MPa, and the test period was 500 h.

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