Preparation method of corrosion-resistant and wear-resistant coating for marine environment

Abstract

The embodiment of the invention provides a preparation method of a marine environment anti-corrosion and wear-resistant coating. The preparation method comprises the steps that a to-be-repaired area on the surface of a workpiece is subjected to cleaning and sand blasting treatment; spherical Ni powder is adopted as first powder for cold spraying, and cold spraying is carried out under the main gas condition to form a first powder coating; irregular WC-17Ni powder is selected as cold spraying second powder, and a second powder coating is formed on the first powder coating in a cold spraying mode under the powder gas feeding condition; cold spraying of the first powder and the second powder is repeated to prepare a gradient composite coating laminated with a first powder coating and a second powder coating; and the gradient composite coating is subjected to coping treatment, so that the surface of the gradient composite coating is recovered to the original molded line of the workpiece. According to the method, the offshore wind power corrosion-resistant and wear-resistant coating can be prepared based on the cold spraying technology. And under the action of a cold spraying process and a gradient composite coating, the compact coating quality in a pressure stress state can be obtained, and the properties of erosion resistance, corrosion resistance and the like of equipment are improved.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the field of surface engineering technology, and specifically relate to a method for preparing a corrosion-resistant and wear-resistant coating for a marine environment. Background Art

[0002] Nuclear power plants require a large amount of cooling water to absorb the heat generated by the reactor. Therefore, the abundance and temperature of the water source are important considerations for site selection. Seawater is an ideal cooling medium due to its abundant resources and low temperature. Therefore, many nuclear power plants are built on the seashore. The erosion of seawater on steel will accelerate the corrosion process. The high salinity unique to the marine environment is also one of the main reasons for accelerated corrosion. Salt can promote electrochemical reactions and accelerate the migration of metal ions. The steel structure of a nuclear power plant is often exposed to humid air. Changes in humidity can also lead to the formation and disappearance of water film on the surface of the steel. This periodic wetting and drying further aggravates the corrosion process. In addition, the activity of microorganisms in the marine environment also poses a threat to steel structures. Some microorganisms can produce highly corrosive substances, which accelerate the corrosion of steel. Under the combined effect of these factors, the corrosion problem of the steel structure of a nuclear power plant is complex and severe, posing a serious challenge to its durability and safety.

[0003] In the field of anti-corrosion of nuclear power plant steel structures, existing anti-corrosion technologies have been applied to a certain extent, but their effectiveness and applicability vary depending on the specific environment. For example, epoxy resins and polyurethane coatings are used for surface protection of nuclear power plant steel structures. These coatings can effectively isolate seawater and air in the initial stage and slow down the corrosion process. However, due to long-term exposure to the marine environment, the coating may degrade due to ultraviolet radiation, temperature changes and mechanical wear, resulting in a decrease in protection effectiveness. Under conditions of strong currents and high salinity, the effectiveness of the cathodic protection system will also be limited, and regular maintenance and replacement of sacrificial anodes are required. Thermal spraying, as a mature surface protection technology, can prepare metal or ceramic coatings on the surface of nuclear power plant steel structures to increase the service life of the workpiece, but the prepared coatings have the problem of large heat input, resulting in defects in the coating structure and reduced mechanical properties and corrosion resistance of the coating. Summary of the invention

[0004] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art and provide a method for preparing a corrosion-resistant and wear-resistant coating for a marine environment.

[0005] One aspect of an embodiment of the present disclosure provides a method for preparing a marine environment anticorrosion and wear-resistant coating, comprising:

[0006] Clean and sandblast the area to be repaired on the workpiece surface;

[0007] Spherical Ni powder is used as the first cold spray powder, and cold spraying is performed under main gas conditions to form a first powder coating;

[0008] Irregular WC-17Ni powder is selected as the second powder for cold spraying, and the second powder coating is formed by cold spraying on the first powder coating under the condition of powder feeding gas;

[0009] Repeating cold spraying of the first powder and the second powder to prepare a gradient composite coating having the first powder coating and the second powder coating stacked on top of each other;

[0010] The gradient composite coating is subjected to a grinding treatment so that the surface of the gradient composite coating is restored to the original profile of the workpiece.

[0011] Optionally, a spherical Ni powder with a particle size of 15 to 45 microns is prepared by a gas atomization method.

[0012] Optionally, a sintering and crushing method is used to prepare irregular WC-17Ni powder with a particle size of 15 to 45 microns.

[0013] Optionally, the distance between the nozzle of the spray gun and the area to be repaired on the surface of the workpiece to be sprayed is 0 to 100 mm.

[0014] Optionally, the main gas conditions include main gas pressure and main gas heating temperature, the main gas pressure is 4-6 MPa, and the main gas is heated to 500-1000° C. by a heater.

[0015] Optionally, the powder feeding conditions include powder feeding air pressure, and the powder feeding air pressure is 4-6 MPa.

[0016] Optionally, the main gas and powder feeding gas include one or two of nitrogen, argon or helium.

[0017] Optionally, the thickness of the gradient composite coating formed by cold spraying is 0 to 3 mm higher than the original workpiece surface.

[0018] Optionally, the thickness of the gradient composite coating formed by cold spraying is higher than 0.4 mm of the original workpiece surface.

[0019] Optionally, during sandblasting, the workpiece surface roughness R a Reach 10 to 300 microns.

[0020] The beneficial effects of the embodiments of the present disclosure include:

[0021] In the present disclosure, the above method can realize the preparation of offshore wind power anti-corrosion and wear-resistant coating based on cold spraying technology. Under the action of cold spraying process and gradient composite coating, dense and compressive stress state coating quality can be obtained, improving the erosion resistance and corrosion resistance of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1A schematic flow chart of a method for preparing a marine environment anticorrosion and wear-resistant coating according to an embodiment of the present disclosure;

[0023] Figure 2 This is a schematic diagram of the processing of a marine environment anti-corrosion and wear-resistant coating according to an embodiment of the present disclosure; wherein the figure illustrates the spraying process of a cold spray gun on the area to be repaired. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0025] The following is a further detailed description of the implementation methods of the present application in conjunction with the accompanying drawings and examples. The detailed descriptions and drawings of the following examples are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments. In the description of the present application, it should be noted that, unless otherwise specified, the meaning of "multiple" is more than two; the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the error tolerance range. "Parallel" is not parallel in the strict sense, but within the error tolerance range.

[0026] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0027] like Figure 1 As shown, a method for preparing a marine environment anticorrosion and wear-resistant coating comprises:

[0028] S101, cleaning and sandblasting the area to be repaired on the surface of the workpiece.

[0029] S102, using spherical Ni powder as the first powder for cold spraying, and performing cold spraying under main gas conditions to form a first powder coating.

[0030] S103, selecting irregular WC-17Ni powder as the second powder for cold spraying, and cold spraying the second powder coating on the first powder coating under powder feeding gas conditions to form the second powder coating.

[0031] S104, repeating the cold spraying of the first powder and the second powder to prepare a gradient composite coating stacked with the first powder coating and the second powder coating.

[0032] S105, performing a grinding process on the gradient composite coating to restore the surface of the gradient composite coating to the original profile of the workpiece, that is, the gradient composite coating is coplanar with the original workpiece surface.

[0033] In the present disclosure, the above method can realize the preparation of offshore wind power anti-corrosion and wear-resistant coating based on cold spraying technology. Under the action of cold spraying process and gradient composite coating, dense and compressive stress state coating quality can be obtained, improving the erosion resistance and corrosion resistance of the equipment.

[0034] In some embodiments, the workpiece includes nuclear power plant equipment or nuclear power plant turbine blades made of carbon steel.

[0035] In some embodiments, spherical Ni powder with a particle size of 15 to 45 microns is prepared by gas atomization.

[0036] In some embodiments, the irregular WC-17Ni powder with a particle size of 15 to 45 microns is prepared by a sintering and crushing method.

[0037] In some embodiments, the distance between the nozzle of the spray gun and the area to be repaired on the surface of the workpiece to be sprayed is 0 to 100 mm.

[0038] In some embodiments, the main gas conditions include main gas pressure and main gas heating temperature. The main gas pressure is 4-6 MPa, and the main gas is heated to 500-1000° C. by a heater.

[0039] In some embodiments, the powder feeding conditions include a powder feeding air pressure, and the powder feeding air pressure is 4-6 MPa.

[0040] In some embodiments, the main gas and the powder feeding gas include one or two of nitrogen, argon or helium.

[0041] In some embodiments, the thickness of the gradient composite coating formed by cold spraying is 0 to 3 mm higher than the original workpiece surface.

[0042] In some embodiments, the thickness of the gradient composite coating formed by cold spraying is higher than 0.4 mm above the original workpiece surface.

[0043] In some embodiments, during the sandblasting process, the surface roughness R of the workpiece is a Reach 10 to 300 microns.

[0044] The beneficial effects of the present disclosure include:

[0045] 1) The area to be repaired is formed by stacking the first powder and the second powder, thereby avoiding cracking in the area to be repaired or nearby.

[0046] 2) The solid phase deposition method adopted by cold spraying avoids the oxidation phase change effect caused by high temperature, and the residual stress of the sprayed coating is small and compressive stress.

[0047] 3) The first powder and the second powder in the gradient composite coating use the same metal element, which avoids galvanic corrosion caused by the potential difference of dissimilar metal elements in the marine climate environment, and at the same time improves the interface compatibility between the first powder and the second powder.

[0048] 4) The second powder, that is, the surface layer is made of WC-17Ni powder prepared by sintering and crushing method. Its irregular morphology is conducive to embedding into the first powder and improving the bonding strength between the first powder and the second powder. At the same time, the second powder has a large mass, and the impact compaction effect generated during the deposition process will improve the bonding strength between the coating and the substrate.

[0049] In one embodiment provided by the present disclosure, a gradient composite coating is prepared by cold spraying technology, which specifically includes the following steps:

[0050] Step 1: Clean (degrease) the area to be repaired, and process it by mechanical polishing to obtain a smooth repair surface, and perform sandblasting to make the surface roughness Ra reach 10 to 300 microns.

[0051] Step 2: Spherical Ni powder with a particle size of 15 to 45 microns prepared by a gas atomization method is used as the first powder for cold spraying, and irregular WC-17Ni powder with a particle size of 15 to 45 microns prepared by a sintering and crushing method is used as the second powder for cold spraying.

[0052] Step 3: Install the cold spray gun and adjust the installation angle so that the cold spray gun is 0 to 100 mm away from the repaired area on the surface of the workpiece to be sprayed and can move synchronously.

[0053] Step 4: Alternately cold spray the first powder and the second powder on the area to be repaired. The cold spray repair material adopts a solid phase deposition method, and the sprayed coating has a compressive stress state. One or two of nitrogen, argon or helium are used as the main gas and powder feeding gas for cold spraying. The main gas pressure is 4-6MPa, the powder feeding gas pressure is 4-6MPa, and the main gas is heated to 500-1000℃ by a heater.

[0054] Step 5: When the thickness of the cold spray repair material layer is 0 to 3 mm higher than the original workpiece surface, it is restored to the original profile by mechanical processing or grinding.

[0055] Specific examples provided by the present disclosure include:

[0056] Example 1: Preparation of protective coating for the surface of nuclear power plant equipment made of carbon steel. Ni powder is used as the first powder and WC-17Ni powder is used as the second powder to prepare a corrosion-resistant and wear-resistant gradient composite coating. Before spraying, the carbon steel substrate (carbon steel nuclear power plant equipment) is first mechanically polished and smoothed, and cleaned with acetone. Before repair, corundum sand is used for sandblasting to obtain a rough surface structure. After the first powder is dried, Figure 2 As shown, during the cold spraying process of the cold spray gun, 4MPa nitrogen at a temperature of 700°C is used as the main gas and 4.2MPa nitrogen is used as the powder feeding gas to prepare the cold spray coating. The operation is stopped after the first powder spraying area exceeds the original workpiece surface by 0.2mm, and the second powder is replaced to prepare the second powder coating on the surface of the first powder coating. The above steps are repeated until the gradient composite coating as a whole exceeds the original workpiece surface by 0.4mm and the operation is stopped. Then mechanical grinding is used to restore the original profile of the coating surface area. After cross-sectional metallographic inspection, the coating is dense and no crack defects are generated.

[0057] Example 2: A protective coating is prepared for the surface of a nuclear power plant turbine blade. Ni powder is used as the first powder and WC-17Ni powder is used as the second powder to prepare a corrosion-resistant and wear-resistant gradient composite coating. Before spraying, the carbon steel substrate (nuclear power plant turbine blade) is first mechanically polished and smoothed, and cleaned with acetone. Before repair, corundum sand is used for sandblasting to obtain a rough surface structure. After the first powder is dried, Figure 2 As shown, during the cold spraying process of the cold spray gun, 4MPa nitrogen at a temperature of 700°C is used as the main gas and 4.2MPa nitrogen is used as the powder feeding gas to prepare the cold spray coating. The operation is stopped after the first powder spraying area exceeds the original workpiece surface by 0.2mm, and the second powder is replaced to prepare the second powder coating on the surface of the first powder coating. The above steps are repeated until the gradient composite coating as a whole exceeds the original workpiece surface by 0.4mm and the operation is stopped. Then mechanical grinding is used to restore the original profile of the coating surface area. After cross-sectional metallographic inspection, the coating is dense and no crack defects are generated.

[0058] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A method for preparing a marine environment anticorrosion and wear-resistant coating, characterized in that: include: Clean and sandblast the area to be repaired on the workpiece surface; Spherical Ni powder is used as the first cold spray powder, and cold spraying is performed under main gas conditions to form a first powder coating; Irregular WC-17Ni powder is selected as the second powder for cold spraying, and the second powder coating is formed by cold spraying on the first powder coating under the condition of powder feeding gas; Repeating cold spraying of the first powder and the second powder to prepare a gradient composite coating having the first powder coating and the second powder coating stacked on top of each other; The gradient composite coating is subjected to a grinding treatment so that the surface of the gradient composite coating is restored to the original profile of the workpiece.

2. The method for preparing a marine environment anticorrosion and wear-resistant coating according to claim 1, characterized in that: Spherical Ni powder with a particle size of 15 to 45 microns was prepared by gas atomization.

3. The method for preparing a marine environment anticorrosion and wear-resistant coating according to claim 1, characterized in that: Irregular WC-17Ni powder with a particle size of 15 to 45 microns was prepared by sintering and crushing method.

4. The method for preparing a marine environment anticorrosion and wear-resistant coating according to claim 1, characterized in that: The distance between the nozzle of the spray gun and the repaired area on the surface of the workpiece to be sprayed is 0 to 100 mm.

5. The method for preparing a marine environment anticorrosion and wear-resistant coating according to claim 1, characterized in that: The main gas conditions include main gas pressure and main gas heating temperature. The main gas pressure is 4-6 MPa, and the main gas is heated to 500-1000° C. by a heater.

6. The method for preparing a marine environment anticorrosion and wear-resistant coating according to claim 1, characterized in that: The powder feeding conditions include the powder feeding air pressure, which is 4-6 MPa.

7. The method for preparing a marine environment anticorrosion and wear-resistant coating according to claim 1, characterized in that: The main gas and powder feeding gas include one or two of nitrogen, argon or helium.

8. The method for preparing a marine environment anticorrosion and wear-resistant coating according to claim 1, characterized in that: The thickness of the gradient composite coating formed by cold spraying is 0 to 3 mm higher than the original workpiece surface.

9. The method for preparing a marine environment anticorrosion and wear-resistant coating according to claim 8, characterized in that: The thickness of the gradient composite coating formed by cold spraying is 0.4 mm higher than that of the original workpiece surface.

10. The method for preparing a marine environment anticorrosion and wear-resistant coating according to claim 1, characterized in that: During sandblasting, the workpiece surface roughness R a Reach 10 to 300 microns.

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