Supersonic spraying / remelting preparation method of diamond-Ni-based corrosion-resistant coating

Abstract

The invention discloses a supersonic spraying / remelting preparation method of a diamond-Ni-based corrosion-resistant coating, and belongs to the technical field of wear-resistant coating preparation. The supersonic spraying / remelting preparation method comprises the steps of powder weighing, Cr-plated diamond preparation, wear-resistant coating preparation through supersonic spraying, high-frequency induction remelting treatment, salt spray corrosion testing and the like. According to the preparation method, the supersonic spraying process and the high-frequency induction process are combined for application, and the preparation method is a diamond corrosion-resistant coating preparation scheme specially designed for strengthening material properties. According to the combined process, understanding of material characteristics is deepened, breakthrough is achieved on the actual operation level, and a solution is provided for many industries depending on high-strength and high-abrasion-resistance surface treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion-resistant coating preparation, that is, a method for preparing a diamond-containing corrosion-resistant coating by using atomized NiCrBSi (Ni45) alloy powder as a coating mother powder and Cr-plated diamond (Cr-plated diamond) as a corrosion-resistant additive phase to prepare a functionalized coating composite powder, and adopting a supersonic spraying / high-frequency induction remelting combination technology to spray the composite powder on the surface of a metal part. Background Art

[0002] Corrosion and wear are the main failure forms of metal components. How to improve the corrosion resistance of metal components has always been a problem that has received much attention and needs to be solved in the engineering industry. In order to improve the surface structure of the material, supersonic spraying, laser cladding and other technologies are often used in engineering to apply a protective coating with higher corrosion resistance than the component substrate on the surface of the metal component to improve the corrosion resistance of the component. Supersonic spraying is to ignite the gas in a high-temperature and high-pressure combustion chamber to generate a high-temperature and high-speed airflow, and use the high-temperature and high-speed airflow to locally melt the powder particles and spray them onto the surface of the substrate to form an adherent coating. The use of supersonic spraying technology to apply corrosion-resistant coatings of metal / ceramic and other materials on the surface of metal components has become a common method in the field of surface protection engineering. However, supersonic spray coatings still have the problems of low powder coating rate and weak interface bonding between coating powder particles, which greatly affect the quality and performance of the coating. At the same time, the corrosion resistance of existing metal materials still cannot meet the corrosion resistance requirements of metal parts operating in extremely harsh environments, and it is urgent to develop new corrosion-resistant materials. Therefore, the present invention adopts a combination of supersonic spraying and high-frequency induction remelting technology to improve the density, organizational structure and corrosion resistance of the coating. Ni45 is a common wear-resistant / corrosion-resistant material, but its supersonic spray coating also has the disadvantages of uneven coating thickness, weak interfacial bonding between powder particles and insufficient corrosion resistance. The literature "Study on the structure and wear and corrosion resistance of arc sprayed Ni-based alloy coating" ([J / OL]. Hot Working Technology, 1-7[2024-10-17].) studied the corrosion resistance of Ni-Al alloy and Ni-Cu alloy coatings, and found that the Ni-Al alloy coating has a slightly higher hardness and slightly higher wear resistance than the Ni-Cu alloy coating; while the corrosion resistance of the Ni-Cu coating is higher than that of the Ni-Al coating, which can significantly improve the corrosion resistance of the substrate in simulated seawater media. It can be seen that each coating in the literature cannot meet the requirements of wear resistance and corrosion resistance at the same time. Therefore, the research and development of a functional coating with 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 in the form of sp 3 The tetrahedral structure formed by the hybrid orbitals is closely arranged, and sp 3It has high bond energy and has good corrosion resistance to most acids, alkalis and other chemicals. If it is combined with diamond Ni45 alloy powder to prepare a corrosion-resistant / wear-resistant coating, the corrosion resistance and wear resistance of the coating can be improved at the same time. However, due to the extremely strong chemical inertness of the diamond surface, it is difficult to achieve metallurgical bonding with the metal matrix, and it is easy to fall off from the coating and fail, thus affecting the corrosion resistance of the coating. In order to solve the above-mentioned problems, the present invention uses Ni45 alloy powder as the coating mother powder and Cr-plated diamond (Cr-plated diamond) as the corrosion-resistant reinforcement phase, and adopts a supersonic spraying process and a high-frequency induction combination technology to first prepare a supersonic spray coating, and then perform a high-frequency induction remelting treatment on the coating. Salt spray corrosion tests show that adding diamond to Ni-based coatings can effectively improve the corrosion resistance of the coating. Summary of the invention

[0003] In order to overcome the above shortcomings and improve the corrosion resistance of supersonic spray coatings, the present invention provides a process method for preparing diamond-Ni-based metal corrosion-resistant coatings using supersonic spraying / remelting combined technology. Cr-plated diamond and Ni45 are mixed in a mass ratio of 10%-50% as functional coating materials, and a corrosion-resistant coating with a thickness of 100μm-200μm is prepared on the surface of metal parts using supersonic spraying technology. The coating is then remelted using high-frequency induction technology to prepare a densified corrosion-resistant coating with Cr-plated diamond as a reinforcing phase and a good interface metallurgical bonding between diamond and base metal.

[0004] The specific technical solutions of the present invention are as follows:

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

[0006] 1) Preparation of Cr-plated diamond: using diamond powder with a particle size of 10-100 μm, and using a physical / chemical combined plating method to plate metal Cr on the surface of the diamond to obtain Cr-plated diamond; the thickness of the Cr-plated layer is 0.1-2 μm;

[0007] 2) Preparation of functionalized coating powder: Powder was prepared according to the mass ratio of 10%-50% of Cr-plated diamond and the remainder of commercially available gas-atomized Ni45 alloy powder with a particle size of 140-325 mesh, and mixed in a three-dimensional mixer for 60 minutes to obtain a functionalized mixed spray powder. The mixed powder was placed in a vacuum oven at 100°C and a vacuum degree of 10 -1 Dry under Pa conditions for 2 h, cool naturally and vacuum package 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 the roughness of the substrate, so as to improve the mechanical bonding strength between the coating and the substrate. Then, the surface of the steel plate substrate after sandblasting is subjected to supersonic spraying. The spraying parameters are: powder feeding speed 5-8kg / h, oxygen flow rate 11.6Nm 3 / h, oxygen pressure 2.0MPa, fuel flow 8.5Nm 3 / h, carrier gas flow rate 10Nm 3 / h, spraying distance 300-360mm, overlapping spraying 10-20 layers;

[0009] 4) High-frequency induction remelting of coating: First, make an induction coil to ensure that the coil can accurately cover the area to be treated. Secondly, 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 treatment. 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, and nitrogen flow rate is 0.2L / min;

[0010] 5) Salt spray corrosion test: Cut the workpiece after plasma spraying / high-frequency induction remelting into samples with a size of 10mm×15mm, and use polymer corrosion-resistant materials to seal the non-sprayed surface. Then, conduct salt spray corrosion resistance test (neutral salt spray test) on the sample. Set the salt spray corrosion conditions: saturator temperature 35-50℃, pH value 6.5-7.2, continuous spraying of medium salt solution, relative humidity in the test box 94±4%, air source pressure 8kg / cm 2 , air inlet pressure 0.2-0.4MPa, spray pressure 0.07-0.15MPa, and experimental period 200-1000h.

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

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

[0013] Preferably, 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 times.

[0014] Preferably, in step 4), the power of the 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.

[0015] Preferably, in step 5), the saturator temperature of the salt spray corrosion test is 35° C., the pH value is 6.7, the air intake pressure is 0.2 MPa, the spray pressure is 0.1 MPa, and the test period is 500 h.

[0016] Beneficial effects:

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

[0018] 2. The present invention combines the two processes of supersonic spraying and high-frequency induction remelting to prepare corrosion-resistant coatings, which can strengthen the metallurgical bonding between the heterogeneous powder particles of the coating and the interface between the coating and the steel plate substrate, effectively improve the density of the coating, and improve the microstructure and corrosion resistance of the coating. The supersonic spray coating has a high porosity and insufficient density, which affects the overall corrosion resistance of the coating. The supersonic coating is subjected to high-frequency induction remelting treatment, so that the sprayed coating is re-melted, and the liquid molten phase can further fill the pores, improve the density and uniformity of the coating, and improve the comprehensive mechanical properties of the coating. At the same time, the remelting process can make the interface between the coating and the substrate more firmly bonded, reduce the risk of delamination or peeling caused by thermal stress, and thus extend the service life of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0020] Figure 2 Surface SEM morphology of the supersonic sprayed coating of Example 1.

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

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

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

[0024] Figure 6 Surface SEM morphology of the high-frequency induction remelted coating of Example 1.

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

[0026] Figure 8Surface SEM morphology of the high-frequency induction remelted coating of Example 1 after salt spray corrosion. DETAILED DESCRIPTION

[0027] Example 1

[0028] 1) Preparation of Cr-plated diamond: A physical / chemical combined plating method is used to plate Cr on 10-15 μm diamond, and the weight gain of Cr plating is 50% of the weight of diamond powder. After plating, the Cr-plated diamond is repeatedly soaked and cleaned with deionized water, and then the washed Cr-plated diamond is placed in an alcohol solution for ultrasonic treatment for 15 minutes, and then 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 powder are weighed and prepared in a weight ratio of 9:1. 900g of atomized Ni45 alloy powder with a particle size of 140-325 mesh and 100g of Cr-plated diamond with a particle size of 10-15μm are weighed, and the two are placed in a three-dimensional mixer and mixed for 60 minutes. After the mixing is completed, they are taken out and vacuum-packed for storage.

[0030] 3) Preparation of corrosion-resistant coating by supersonic spraying: Select low-carbon steel with a substrate size of 200mm×50mm×5mm, and perform pretreatment such as sandblasting to remove rust / roughen the substrate surface. Put the mixed powder into the supersonic spray powder tank. Set the process parameters: powder feeding speed 6kg / h, oxygen flow rate 11.6Nm 3 / h, oxygen pressure 2.0MPa, fuel flow 8.5Nm 3 / h, carrier gas flow rate 10.0Nm 3 / h, spraying distance 320mm, spraying 15 layers.

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

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

[0033] The porosity of the supersonic spray coating in this embodiment is 2.23%, and the porosity of the coating after remelting is 1.17%. The porosity after remelting is about 48% lower than that before remelting. The initial weight of the supersonic spray coating is 7.093g, and the weight after corrosion is 7.045g, and the weight difference before and after corrosion is 0.048g. The weight of the remelted coating before corrosion is 6.558g, and the weight after corrosion is 6.536g, and the weight difference before and after corrosion is 0.022g. The corrosion resistance after remelting is about 2.2 times higher than that before remelting.

[0034] Figure 1 The XRD diagram of the supersonic spray coating shows that the substances corresponding to the strong diffraction peaks are solid solution Ni and diamond, indicating that diamond can be effectively and completely retained in the coating. The high temperature heat source during the spraying process promotes the chemical reaction between Ni, Si and B. The boride (Ni3B) and silicide (Ni3Si) in the coating usually have high hardness and good heat resistance, which makes them play a role in enhancing the corrosion resistance and high temperature resistance of the coating. At the same time, phases such as CrB and Cr7C3 are also generated.

[0035] Figure 2 This is the surface SEM morphology of the supersonic spray coating. It can be found that the powder particles on the surface of the coating are arranged in relief, the thickness of the coating is uneven, but there are fewer pores and cracks, and the coating quality is relatively good.

[0036] Figure 3 This is the XRD diagram of the supersonic spray coating after salt spray corrosion. The main phases on the coating surface are: NiO, Cr2O3, Ni2O3, CrC l3 and NiC l2 The oxides NiO, Cr2O3 and Ni2O3 appear during the corrosion process when Ni and Cr in the original sample, which have strong oxidation resistance, react with oxygen.

[0037] Figure 4 This is the surface SEM morphology of the supersonic spray coating after salt spray corrosion. It can be found that the looseness of the coating is further aggravated after corrosion. New slag-like oxides or chlorides are generated on the surface of the coating. The newly generated corrosion shell structure is denser and smoother, which can form a certain area of ​​protection inside the area covered by it and slow down the corrosion rate of its internal organization. However, when the corrosion occurs to a certain extent, more loose holes appear in the lower structure of the corrosion shell, and some areas fall off, exposing the internal coating. Corrosion will continue here, and cracks appear in some corrosion layers.

[0038] Figure 5This is the XRD diagram of the high-frequency induction remelting coating. It can be seen that after the high-frequency induction remelting treatment, the phase structure of the coating changes. Part of the Ni in the solid solution reacts with B to regenerate Ni4B3; part of the Si reacts with C to form SiC phase.

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

[0040] Figure 7 This is the XRD diagram of the high-frequency induction remelted coating after salt spray corrosion. The corresponding oxides and chlorides of Cr and Ni are also generated in the coating, but the peak intensity of these compounds is weaker than before.

[0041] Figure 8 This is the surface SEM morphology of the high-frequency induction remelted coating after salt spray corrosion. It can be observed that the surface density and continuity of the remelted sample are good, the apparent corrosion area is reduced, and 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 in Example 1 was placed in a supersonic spraying device, and the spraying process parameters were changed: powder feeding speed 6 kg / h, oxygen flow rate 10.0 Nm 3 / h, oxygen pressure 2.2MPa, fuel flow 8.0Nm 3 / h, carrier gas flow rate 10.0Nm 3 / h, spraying distance 340mm, spraying 12 layers.

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

[0045] Change the salt spray corrosion conditions: saturator temperature 40℃, pH value 7, the spraying method of the corrosive salt solution is continuous spraying, the relative humidity in the sample cavity is 94±4%, and the air source is 8kg / cm 2 , air intake pressure 0.3MPa, spray pressure 0.13MPa, and experimental period 500h.

[0046] In this example, the porosity of the supersonic spray coating is 2.73%, and the porosity of the coating after remelting is 1.39%. The porosity after remelting is about 49% lower than that before remelting. The weight of the supersonic spray coating before corrosion is 8.266g, and the weight after corrosion is 8.221g. The weight difference before and after corrosion is 0.045g. The weight of the remelted coating before corrosion is 7.258g, and the weight after corrosion is 7.231g. The weight difference before and after corrosion is 0.027g. Therefore, by comparing the weight loss of the samples before and after corrosion, it can be found that the corrosion resistance of the samples after remelting is improved by about 40% compared with that before remelting.

[0047] Example 3

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

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

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

[0051] In this example, the porosity of the supersonic spray coating is 2.03%, and the porosity of the coating after remelting is 1.22%. The porosity after remelting is about 39% lower than that before remelting. The weight of the supersonic spray coating before corrosion is 9.511g, and the weight after corrosion is 9.465g, and the weight difference before and after corrosion is 0.046g. The weight of the remelted coating before corrosion is 7.144g, and the weight after corrosion is 7.110g, and the weight difference before and after corrosion is 0.034g. The corrosion resistance of the sample after remelting is about 26% higher than that before remelting.

[0052] Example 4

[0053] Preparation of coating powder: Change the weight ratio of Ni45 alloy powder to diamond 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 them for 60 minutes. After mixing, take them out for use.

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

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

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

[0057] In this example, the porosity of the supersonic spray coating is 2.53%, and the porosity of the coating after remelting is 1.37%. The porosity after remelting is about 46% lower than that before remelting. The weight of the supersonic spray coating before corrosion is 7.298g, and the weight after corrosion is 7.245g, and the weight difference before and after corrosion is 0.053g. The weight of the remelted coating before corrosion is 8.949g, and the weight after corrosion is 8.913g, and the weight difference before and after corrosion is 0.036g. The comparison results show that the corrosion resistance of the sample after remelting is improved by about 32% compared with that before remelting.

[0058] Example 5

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

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

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

[0062] Change the salt spray corrosion conditions: saturator temperature 50℃, pH value 6.8, salt solution spraying method is continuous spraying, relative humidity 94±4%, air source 8kg / cm 2 , air inlet pressure 0.25MPa, spray pressure 0.14MPa, and experimental period 500h.

[0063] In this example, the porosity of the supersonic spray coating is 2.79%, and the porosity of the coating after remelting is 1.56%. The porosity after remelting is about 44% lower than that before remelting. The weight of the supersonic spray coating before corrosion is 7.295g, and the weight after corrosion is 7.237g, and the weight difference before and after corrosion is 0.058g. The weight of the remelted coating before corrosion is 6.574g, and the weight after corrosion is 6.541, and the weight difference before and after corrosion is 0.033. The comparison results show that the corrosion resistance of the sample after remelting is about 43% higher than that before remelting.

[0064] Example 6

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

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

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

[0068] Change the salt spray corrosion conditions: saturator temperature 44℃, pH value 7.0, salt solution spraying method is continuous spraying, relative humidity 94±4%, air source 8kg / cm 2 , air intake pressure 0.4MPa, spray pressure 0.09MPa, and experimental period 500h.

[0069] In this example, the porosity of the supersonic spray coating is 3.22%, and the porosity of the coating after remelting is 2.05%. The porosity after remelting is about 36% lower than that before remelting. The weight of the supersonic spray coating before corrosion is 7.249g, and the weight after corrosion is 7.205g, and the weight difference before and after corrosion is 0.044g. The weight of the remelted coating before corrosion is 9.400g, and the weight after corrosion is 9.375g, and the weight difference before and after corrosion is 0.025g. The comparison results show that the corrosion resistance of the sample after remelting is improved by about 43% compared with that before remelting.

Claims

1. A supersonic spraying / remelting method for preparing a diamond-Ni-based corrosion-resistant coating comprises the following steps: 1) Preparation of Cr-plated diamond: using diamond powder with a particle size of 10-100 μm, and using a physical / chemical combined plating method to plate metal Cr on the surface of the diamond to obtain Cr-plated diamond; the thickness of the Cr-plated layer is 0.1-2 μm; 2) Preparation of functionalized coating powder: Powder was prepared according to the mass ratio of 10%-50% of Cr-plated diamond and the remainder of commercially available gas-atomized Ni45 alloy powder with a particle size of 140-325 mesh, and mixed in a three-dimensional mixer for 60 minutes to obtain a functionalized mixed spray powder. The mixed powder was placed in a vacuum oven at 100°C and a vacuum degree of 10 -1 Dry under Pa conditions for 2 h, cool naturally and vacuum package 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 the roughness of the substrate, so as to improve the mechanical bonding strength between the coating and the substrate. Then, the surface of the steel plate substrate after sandblasting is subjected to supersonic spraying. The spraying parameters are: powder feeding speed 5-8kg / h, oxygen flow rate 11.6Nm 3 / h, oxygen pressure 2.0MPa, fuel flow 8.5Nm 3 / h, carrier gas flow rate 10Nm 3 / h, spraying distance 300-360mm, overlapping spraying 10-20 layers; 4) High-frequency induction remelting of coating: First, make an induction coil to ensure that the coil can accurately cover the area to be treated. Secondly, 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 treatment. 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, and nitrogen flow rate is 0.2L / min; 5) Salt spray corrosion test: Cut the workpiece after plasma spraying / high-frequency induction remelting into samples with a size of 10mm×15mm, and use polymer corrosion-resistant materials to seal the non-sprayed surface. Then, conduct salt spray corrosion resistance test on the sample. Set the salt spray corrosion conditions: saturator temperature 35-50℃, pH value 6.5-7.2, continuous spraying of medium salt solution, relative humidity in the test box 94±4%, air source pressure 8kg / cm 2 , air inlet pressure 0.2-0.4MPa, spray pressure 0.07-0.15MPa, and experimental period 200-1000h.

2. The supersonic spraying / remelting preparation method of a diamond-Ni based corrosion resistant coating according to claim 1, characterized in that: The particle size of the diamond powder in step 1) is 10-15 μm, and the thickness of the Cr-plated layer is 1-2 μm.

3. The supersonic spraying / remelting preparation method of a diamond-Ni based corrosion resistant coating according to claim 1, characterized in that: The components of the Ni45 alloy powder in step 2) are in a weight ratio of Cr 27%, Si 8%, Fe 4%-7%, B 4.5%, C 0.9%-1.2%, and the remainder is Ni; the mass ratio of the Ni45 alloy powder to the Cr-plated diamond powder is 9:

1.

4. The supersonic spraying / remelting preparation method of a diamond-Ni based corrosion resistant coating 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 times.

5. The supersonic spraying / remelting preparation method of a diamond-Ni based corrosion resistant coating 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 of remelting is 25 s.

6. The supersonic spraying / remelting preparation method of a diamond-Ni based corrosion resistant coating according to claim 1, characterized in that: Step 5) The saturator temperature of the salt spray corrosion test is 35°C, the pH value is 6.7, the inlet pressure is 0.2Mpa, the spray pressure is 0.1MPa, and the experimental period is 500h.

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