Vacuum pump part composite coating preparation method, composite coating structure and vacuum pump

Abstract

The invention discloses a vacuum pump part composite coating preparation method, a composite coating structure and a vacuum pump. The preparation method of the composite coating of the vacuum pump part comprises the following steps: step 1, pre-treating the part, including ultrasonic cleaning, chemical oil removal, acid pickling activation, water washing and drying treatment which are performed in sequence; (2) the NiCoCrAlY alloy powder is prepared into a NiCoCrAlY layer on the part through a laser cladding process, and the NiCoCrAlY layer is prepared from the NiCoCrAlY alloy powder; (3) the NiCoCrAlY layer is subjected to machining treatment to meet the preset requirement; step 4, carrying out pre-plating treatment on the part, wherein the pre-plating treatment comprises ultrasonic cleaning, ultrapure water cleaning and drying treatment which are carried out in sequence; 5, the part is put into the prefabricated chemical plating solution, and a NiP layer is formed on the surface of the part through chemical reaction; and 6, the part is subjected to post-plating treatment, so that the part with the NiCoCrAlY / NiP composite plating layer is obtained. According to the preparation method of the composite coating for the vacuum pump part, the high temperature resistance and corrosion resistance of the part can be improved.

Description

Technical Field

[0001] The embodiments of this invention relate to the field of metal electroplating technology. More specifically, this invention relates to a method for preparing a composite coating for vacuum pump components, a composite coating structure, and a vacuum pump. Background Technology

[0002] Vacuum pumps are used to remove gas from a vacuum chamber, reducing its vacuum level to below standard atmospheric pressure. They are now widely used in many industries such as semiconductors, photovoltaic solar energy, new energy batteries, and aerospace.

[0003] However, with the continuous upgrading of production processes, these industries often involve high temperatures and highly corrosive media. When faced with complex conditions such as high temperatures and strong corrosion, the heat and corrosion resistance of vacuum pump components is limited, making them unable to adapt to increasingly demanding and complex conditions. Over time, these components experience severe high-temperature deformation and corrosion, leading to a decline in vacuum pump performance, system downtime, and even pump failure due to thermal deformation or corrosion. This significantly shortens the service life of components, causing substantial economic losses and increased production cycles for these industries, and posing certain safety risks. Therefore, the application of vacuum pumps in demanding processes is severely restricted. Summary of the Invention

[0004] To address one or more of the technical problems mentioned above, this invention provides a method for preparing a composite coating on vacuum pump components, a composite coating structure, and a vacuum pump, so as to form a composite coating on vacuum pump components to improve the high temperature resistance and corrosion resistance of the components.

[0005] According to a first aspect of the present invention, a method for preparing a composite coating for a vacuum pump component is provided. The method includes the following steps: Step 1, pre-treating the component, which includes sequential ultrasonic cleaning, chemical degreasing, acid pickling activation, water washing, and drying; Step 2, preparing a NiCoCrAlY layer on the component using a laser cladding process with NiCoCrAlY alloy powder; Step 3, processing the NiCoCrAlY layer to a predetermined requirement; Step 4, performing a pre-plating treatment on the component, which includes sequential ultrasonic cleaning, ultrapure water cleaning, and drying; Step 5, immersing the component in a pre-prepared chemical plating solution to form a NiP layer on the surface of the component through a chemical reaction; Step 6, performing a post-plating treatment on the component to obtain a component with a NiCoCrAlY / NiP composite coating.

[0006] In some embodiments, step one further includes: ultrasonic cleaning using acetone or anhydrous alcohol for 10–40 min; chemical degreasing using a NaOH solution with a concentration of 10–100 g / L for 10–40 min at a temperature of 60–90 °C; and acid washing activation using a hydrochloric acid solution or a sulfuric acid solution with a concentration of 10–30% for 2–10 min at a temperature of 40–70 °C. Each step is followed by rinsing with ultrapure water for 10–120 s.

[0007] In some embodiments, step two further includes: the drying temperature range of the NiCoCrAlY alloy powder is 60 to 300°C, the drying time range of the NiCoCrAlY alloy powder is 5 to 300 min, and the laser cladding process adopts argon protection and single-tube powder feeding method.

[0008] In some embodiments, the laser cladding process includes: an argon flow rate of 5–15 NL / min, a laser power of 500–2000 W, a laser scanning speed of 2–15 mm / s, a laser defocusing amount of 8–20 mm, a powder feeding rate of 5.0–30.0 g / min, an overlap rate of 10–60%, and a NiCoCrAlY layer thickness of 200–1200 μm.

[0009] In some embodiments, step three further includes: processing the NiCoCrAlY layer from step two to meet the usage requirements and roughness requirements of the component, wherein the thickness of the NiCoCrAlY layer ranges from 5 to 200 μm.

[0010] In some embodiments, step four further includes: ultrasonic cleaning using acetone or anhydrous alcohol for 10 to 30 minutes; and ultrapure water cleaning for 10 to 120 seconds.

[0011] In some embodiments, step five further includes: the pre-prepared chemical plating solution contains 10-50 g / L nickel sulfate, 20-60 g / L sodium hypophosphite, 10-50 g / L lactic acid, 10-55 g / L sodium glycolate, 5-40 g / L citric acid, 2-20 g / L succinic acid, 0.05-20 g / L sodium thiosulfate, 0.05-20 g / L potassium zinc sulfate, 0.1-20 ppm thiourea, 0.05-10 g / L ammonium fluoride, 5-40 g / L sodium acetate, and 5-40 mmol / L malonyl lactone; the pH of the pre-prepared chemical plating solution is 3.5-6.5, and the temperature is 40-95°C.

[0012] In some embodiments, step six further includes: annealing heat treatment, ultrapure water cleaning and drying treatment of the parts. The annealing heat treatment process is 100-200°C, held for 1-5 hours, and then cooled to room temperature in the furnace before being taken out. The ultrapure water cleaning time is 10-120 seconds.

[0013] According to a second aspect of the present invention, a composite coating structure for a vacuum pump component is provided, prepared according to the above-described method for preparing a composite coating for a vacuum pump component, comprising an aluminum alloy substrate, and a NiCoCrAlY layer and a NiP layer sequentially prepared from the inside to the outside on the aluminum alloy substrate.

[0014] According to a third aspect of the present invention, a vacuum pump is provided, comprising an aluminum alloy part and the aforementioned vacuum pump component composite coating structure.

[0015] Through the above-described method for preparing composite coatings for vacuum pump components, the composite coating structure, and the vacuum pump, a NiCoCrAlY / NiP composite coating is formed on the surface of the components. This NiCoCrAlY / NiP composite coating has the following advantages: 1) The NiCoCrAlY / NiP composite coating possesses extremely strong bonding performance; even under complex working conditions, it is not prone to cracking, delamination, or peeling; 2) The NiCoCrAlY / NiP composite coating in this application is more dense and has excellent corrosion resistance, providing better protection for the components. It provides dual protection, giving it extremely strong corrosion resistance and the ability to withstand more stringent processes; 3) The NiCoCrAlY / NiP composite coating has excellent wear resistance; 4) The NiCoCrAlY / NiP composite coating has excellent high-temperature resistance, withstanding temperatures below 250℃ for extended periods without cracking or peeling, and withstanding temperatures up to 450℃; 5) The NiCoCrAlY / NiP composite coating is non-toxic, environmentally friendly, and safe, with uniform thickness and a smart and simple preparation process, resulting in lower maintenance costs for the protected equipment, significant cost reduction, and savings in component materials, thus possessing good social and economic benefits. Attached Figure Description

[0016] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0017] Figure 1 This is a flowchart illustrating the steps of a method for preparing a composite coating for vacuum pump components according to an embodiment of the present invention.

[0018] Figure 2 A simplified flowchart of the method for preparing composite coatings for vacuum pump components according to an embodiment of the present invention is shown;

[0019] Figure 3 This is a schematic diagram of the composite coating structure of the vacuum pump components according to an embodiment of the present invention;

[0020] Figure 4 This is a partial structural schematic diagram of the vacuum pump according to an embodiment of the present invention;

[0021] Figure 5 for Figure 4 The diagram shows an enlarged view of the vacuum pump at point A. Detailed Implementation

[0022] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0023] According to a first aspect of the present invention, a method 100 for preparing a composite coating for a vacuum pump component is provided. Figure 1 The steps of a method 100 for preparing a composite coating for a vacuum pump component according to an embodiment of the present invention are shown. Figure 2 A simplified process for a method 100 for preparing a composite coating on vacuum pump components according to an embodiment of the present invention is shown. (Combined with...) Figure 1 and Figure 2 As shown, the steps of the composite coating preparation method 100 for vacuum pump components include:

[0024] Step S1 involves pre-treating the parts, which includes sequential ultrasonic cleaning, chemical degreasing, acid pickling and activation, water washing, and drying.

[0025] Specifically, the components undergo ultrasonic cleaning, chemical degreasing, and acid pickling activation in sequence. After each step, they are rinsed with ultrapure water and finally dried.

[0026] In some embodiments, the process conditions for pre-cladding treatment of components are as follows: ultrasonic cleaning uses acetone or anhydrous alcohol for 10–40 min; chemical degreasing uses a NaOH solution with a content of 10–100 g / L for 10–40 min at a temperature of 60–90 °C; acid pickling activation uses a HCl solution (hydrochloric acid solution) with a content of 10–30% (mass fraction) or a sulfuric acid solution with a content of 10–30% (mass fraction) for 2–10 min at a temperature of 40–70 °C; and each ultrapure water cleaning takes 10–120 s.

[0027] In this application, the preferred values ​​of the above process conditions are as follows: ultrasonic cleaning uses anhydrous alcohol for 20 minutes; chemical degreasing uses a 50 g / L NaOH solution for 20 minutes at a temperature of 70°C; acid washing activation uses a 20% hydrochloric acid solution for 3 minutes at a temperature of 50°C; and each ultrapure water cleaning takes 20 seconds.

[0028] Step 2 (S2): NiCoCrAlY alloy powder is used to prepare a NiCoCrAlY layer on the component through laser cladding process.

[0029] Specifically, the laser cladding process can employ argon protection and a single-tube powder feeding method, and the coating can be prepared by controlling process parameters such as laser power, laser scanning speed, laser defocusing amount, powder feeding rate, and overlap rate.

[0030] In some embodiments, step S2 further includes: the drying temperature range of NiCoCrAlY alloy powder is 60 to 300°C, the drying time range of NiCoCrAlY alloy powder is 5 to 300 min, and the laser cladding process adopts argon protection and single-tube powder feeding method.

[0031] In some embodiments, the laser cladding process includes: an argon flow rate of 5–15 NL / min, a laser power of 500–2000 W, a laser scanning speed of 2–15 mm / s, a laser defocusing amount of 8–20 mm, a powder feeding rate of 5.0–30.0 g / min, an overlap rate of 10–60%, and a NiCoCrAlY layer thickness of 200–1200 μm.

[0032] In this application, the preferred process conditions are as follows: NiCoCrAlY alloy powder drying temperature is 120℃, drying time is 180min, argon flow rate is 10NL / min (AIR 20℃ atm), laser power is 800W, laser scanning speed is 8mm / s, laser defocusing amount is 15mm, powder feeding rate is 10.0g / min, and overlap rate is 20%; the NiCoCrAlY layer thickness is 300μm.

[0033] In this application, the NiCoCrAlY alloy powder is an alloy of nickel (Ni), cobalt (Co), chromium (Cr), aluminum (Al), and yttrium (Y).

[0034] Step 3 (S3): Process the NiCoCrAlY layer to the preset requirements.

[0035] Specifically, in some embodiments, step three S3 may include: processing the NiCoCrAlY layer from step two S2 to meet the usage requirements and roughness requirements of the component, and ensuring that the thickness of the NiCoCrAlY layer is in the range of 5 to 200 μm.

[0036] In this application, preferably, the thickness of the NiCoCrAlY layer can be maintained at 20–30 μm.

[0037] Step 4 (S4) involves pre-plating treatment of the parts, which includes ultrasonic cleaning, ultrapure water cleaning, and drying in sequence.

[0038] Specifically, the process conditions can be as follows: ultrasonic cleaning uses acetone or anhydrous alcohol, and the cleaning time is 10 to 30 minutes; ultrapure water cleaning time is 10 to 120 seconds.

[0039] In this application, the preferred process conditions are: ultrasonic cleaning using acetone or anhydrous alcohol for 20 minutes; and ultrapure water cleaning for 30 seconds.

[0040] Step S5: Place the component into a chemical plating bath containing a pre-prepared chemical plating solution, and form a NiP layer on the surface of the component through a chemical reaction.

[0041] In this application, NiP layer refers to a P-type semiconductor layer containing nickel.

[0042] Specifically, the detailed preparation process is as follows: the NiCoCrAlY layer components that have undergone the pretreatment in step four (S4 plating) are placed in a chemical plating tank containing a pre-prepared chemical plating solution. A NiP layer is deposited on the surface of the components through a chemical reaction. After the chemical plating is completed, the components are promptly cleaned with ultrapure water and dried.

[0043] In some embodiments, step five S5 further includes:

[0044] A pre-prepared chemical plating solution was prepared, comprising: nickel sulfate 10–50 g / L, sodium hypophosphite 20–60 g / L, lactic acid 10–50 g / L, sodium glycolate 10–55 g / L, citric acid 5–40 g / L, succinic acid 2–20 g / L, sodium thiosulfate 0.05–20 g / L, potassium zinc sulfate 0.05–20 g / L, thiourea 0.1–20 ppm, ammonium fluoride 0.05–10 g / L, sodium acetate 5–40 g / L, and malonyl lactone 5–40 mmol / L. The controlled conditions were: pH 3.5–6.5, temperature 40–95 °C, NiP layer thickness 5–40 μm, and ultrapure water rinsing time 10–120 s.

[0045] In this application, the preferred process conditions are as follows: in the pre-prepared chemical plating solution, nickel sulfate 20-25 g / L, sodium hypophosphite 30-35 g / L, complexing agents: lactic acid 25 g / L (main complexing agent), sodium glycolate 30 g / L (auxiliary complexing agent), citric acid 15 g / L (auxiliary complexing agent), succinic acid 5-10 g / L (auxiliary complexing agent), stabilizers: sodium thiosulfate 0.4 g / L, potassium iodide 0.1 g / L, thiourea 1-3 ppm, ammonium fluoride 0.3-0.5 g / L, sodium acetate 18 g / L (buffer), propionic acid 7 mL / L (accelerator), pH value 4.7-5.1, temperature 86℃; NiP layer thickness 15 μm; ultrapure water rinsing time 30 s.

[0046] Step S6 involves post-plating treatment of the parts to ultimately obtain parts with a NiCoCrAlY / NiP composite coating.

[0047] Specifically, the detailed preparation process is as follows: The parts with the chemically plated NiP layer in step S5 are placed in a heat treatment furnace for annealing heat treatment. After the heat treatment is completed, the parts are promptly cleaned with ultrapure water and dried.

[0048] In some embodiments, step six S6 further includes: subjecting the components with the chemically plated NiP layer from step five S5 to annealing heat treatment, ultrapure water cleaning, and drying treatment. The annealing heat treatment process is 100-200°C, held at that temperature for 1-5 hours, and then cooled to room temperature in the furnace before being removed. The ultrapure water cleaning time is 10-120 seconds.

[0049] In this application, the preferred values ​​of the process conditions are: the annealing heat treatment process is 150°C, held for 3 hours and then cooled to room temperature in the furnace before being taken out; the ultrapure water cleaning time is 30 seconds.

[0050] A second aspect of the present invention also provides a composite coating structure 200 for a vacuum pump component, which is prepared according to the above-described method 100 for preparing a composite coating for a vacuum pump component. For example... Figure 3 As shown, the composite coating structure 200 of the vacuum pump component includes an aluminum alloy substrate 201, and a NiCoCrAlY layer 202 and a NiP layer 203 sequentially formed from the inside to the outside on the aluminum alloy substrate 201.

[0051] In summary, the vacuum pump component composite coating preparation method 100 and composite coating structure 200 according to embodiments of the present invention form a NiCoCrAlY / NiP composite coating on the surface of the component. This NiCoCrAlY / NiP composite coating has the following advantages:

[0052] 1) The NiCoCrAlY coating prepared by laser cladding is bonded to the protected parts in a metallurgical manner. At the same time, the NiCoCrAlY coating, as a bonding layer, has the same main element as the NiP coating, which is Ni. The difference in thermal expansion properties between the two is smaller, which makes the NiCoCrAlY / NiP composite coating have extremely strong bonding performance. Even under complex working conditions, the NiCoCrAlY / NiP composite coating is not easy to crack, delaminate, or peel off.

[0053] 2) Because the coating prepared by laser cladding has the characteristics of continuous and dense structure, no pores and no microcracks, the NiCoCrAlY / NiP composite coating in this application is more dense. Moreover, both NiCoCrAlY and NiP have excellent corrosion resistance, which provides dual protection for the parts, making them extremely corrosion resistant and able to withstand more stringent processes.

[0054] 3) In this application, the hardness range of NiCoCrAlY is 450-650HV, and the hardness range of NiP is 450-600HV. Both NiCoCrAlY and NiP have high hardness, which makes the NiCoCrAlY / NiP composite coating have excellent wear resistance.

[0055] 4) NiCoCrAlY is a nickel-based high-temperature alloy with a maximum resistance of 1200℃, while NiP has a maximum resistance of 450℃. Therefore, the NiCoCrAlY / NiP composite coating has excellent high-temperature resistance, and can withstand temperatures below 250℃ for a long time without cracking or peeling, with a maximum resistance of 450℃.

[0056] 5) The NiCoCrAlY / NiP composite coating is non-toxic, environmentally friendly, and safe. It has uniform thickness and a smart and simple preparation process, which enables the protected equipment to have lower maintenance costs, significantly reduces costs, saves parts and materials, and has good social and economic benefits.

[0057] According to a third aspect of the present invention, a vacuum pump is provided. Figure 4 and Figure 5 A partial structure of a vacuum pump 300 according to an embodiment of the present invention is shown. For example... Figure 4 As shown, the vacuum pump includes an aluminum alloy part and the aforementioned vacuum pump component composite coating structure 200.

[0058] In this application, aluminum alloy parts can be taken as 7-series aluminum alloy materials. After preparing a NiCoCrAlY / NiP composite coating on it, high temperature and strong corrosion tests are performed to prove that the composite coating has extremely strong bonding performance, heat resistance and corrosion resistance, and is capable of being used in harsh processes.

[0059] In the foregoing description of this application, unless otherwise expressly specified and limited, the terms "fixed," "installed," "connected," or "linked" should be interpreted broadly. For example, the term "linked" can refer to a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; or it can refer to the internal communication of two components or the interaction between two components. Therefore, unless otherwise expressly limited in this application, those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0060] Based on the above description of this application, those skilled in the art will also understand that the terms used, such as "upper," "lower," "front," "rear," "left," "right," "length," "width," "thickness," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," "center," "longitudinal," "transverse," "clockwise," or "counterclockwise," are based on the orientation or positional relationship shown in the accompanying drawings of this application. They are only for the purpose of facilitating the explanation of the present invention and simplifying the description, and do not explicitly or implicitly suggest that the device or element involved must have the specific orientation, or be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms should not be understood or interpreted as a limitation on the present invention.

[0061] Furthermore, the terms "first" or "second," etc., used in this application to refer to numbers or ordinal numbers are for descriptive purposes only and should not be construed as explicitly or implicitly indicating relative importance or specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, or more, unless otherwise explicitly specified.

[0062] While numerous embodiments of the invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of the invention. The appended claims are intended to define the scope of protection of the invention and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A method for preparing a composite coating for vacuum pump components, characterized in that, The preparation method includes the following steps: Step 1 involves pre-treating the parts, which includes ultrasonic cleaning, chemical degreasing, acid pickling and activation, water washing, and drying. Step 2: NiCoCrAlY alloy powder is used to prepare a NiCoCrAlY layer on the component through laser cladding process; Step 3: Process the NiCoCrAlY layer to the preset requirements; Step four involves pre-plating treatment of the parts, which includes ultrasonic cleaning, ultrapure water cleaning, and drying in sequence. Step 5: Place the components into the pre-prepared chemical plating solution to form a NiP layer on the surface of the components through a chemical reaction; Step six: Perform post-plating treatment on the parts to obtain parts with NiCoCrAlY / NiP composite coating.

2. The method for preparing composite coatings for vacuum pump components according to claim 1, characterized in that, Step one further includes: ultrasonic cleaning using acetone or anhydrous alcohol for 10–40 min; chemical degreasing using a NaOH solution with a concentration of 10–100 g / L for 10–40 min at a temperature of 60–90 °C; and acid washing activation using a hydrochloric acid solution or a sulfuric acid solution with a concentration of 10–30% for 2–10 min at a temperature of 40–70 °C. After each step, ultrapure water is used for rinsing, with each ultrapure water rinse lasting 10–120 s.

3. The method for preparing composite coatings for vacuum pump components according to claim 1, characterized in that, Step two further includes: the drying temperature range of the NiCoCrAlY alloy powder is 60-300℃, the drying time range of the NiCoCrAlY alloy powder is 5-300min, and the laser cladding process adopts argon protection and single-tube powder feeding method.

4. The method for preparing composite coatings for vacuum pump components according to claim 3, characterized in that, The laser cladding process includes: an argon flow rate of 5–15 NL / min, a laser power of 500–2000 W, a laser scanning speed of 2–15 mm / s, a laser defocusing amount of 8–20 mm, a powder feeding rate of 5.0–30.0 g / min, an overlap rate of 10–60%, and a NiCoCrAlY layer thickness of 200–1200 μm.

5. The method for preparing composite coatings for vacuum pump components according to claim 1, characterized in that, Step three further includes: processing the NiCoCrAlY layer from step two to meet the usage and roughness requirements of the component, wherein the thickness of the NiCoCrAlY layer ranges from 5 to 200 μm.

6. The method for preparing composite coatings for vacuum pump components according to claim 1, characterized in that, Step four further includes: ultrasonic cleaning using acetone or anhydrous alcohol for 10-30 minutes; and ultrapure water cleaning for 10-120 seconds.

7. The method for preparing composite coatings for vacuum pump components according to claim 1, characterized in that, Step five further includes: the pre-prepared chemical plating solution contains 10-50 g / L nickel sulfate, 20-60 g / L sodium hypophosphite, 10-50 g / L lactic acid, 10-55 g / L sodium glycolate, 5-40 g / L citric acid, 2-20 g / L succinic acid, 0.05-20 g / L sodium thiosulfate, 0.05-20 g / L potassium zinc sulfate, 0.1-20 ppm thiourea, 0.05-10 g / L ammonium fluoride, 5-40 g / L sodium acetate, and 5-40 mmol / L malonyl lactone; the pH of the pre-prepared chemical plating solution is 3.5-6.5, and the temperature is 40-95℃.

8. The method for preparing a composite coating for vacuum pump components according to any one of claims 1-7, characterized in that, Step six further includes: annealing heat treatment, ultrapure water cleaning and drying treatment of the parts. The annealing heat treatment process is 100-200℃, held for 1-5 hours and then cooled to room temperature in the furnace before being taken out. The ultrapure water cleaning time is 10-120 seconds.

9. A composite coating structure for vacuum pump components, prepared according to the method for preparing composite coatings for vacuum pump components according to any one of claims 1 to 8, characterized in that, It includes an aluminum alloy substrate, and NiCoCrAlY and NiP layers sequentially formed from the inside to the outside on the aluminum alloy substrate.

10. A vacuum pump, characterized in that, It includes aluminum alloy parts and a composite coating structure for vacuum pump components as described in claim 9.

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