Pipe inner wall arc ion plating equipment and plating method

Abstract

The invention discloses tube inner wall arc ion plating equipment and a plating method, the tube inner wall arc ion plating equipment comprises a plating container composed of an upper chamber and a lower chamber, the lower chamber is movably butted with the upper chamber to form a closed chamber, the upper chamber is provided with a clamping fixture for positioning a tubular workpiece to be plated, an arc striking needle is located at the axis of the workpiece, the arc striking needle and a target strike arc for discharging, and an anode is arranged on the outer side to form a loop. A target material is vertically arranged on the outer side of a workpiece in the lower cavity, a coil magnetic field is arranged between the two cavities, and the magnetic field penetrates through the lower cavity to restrain an arc spot track, so that plasmas are evenly distributed along the target material and conveyed to the inner wall of the workpiece in a controlled mode. Through cooperative control of a planar arc source and a coil magnetic field, high-ionization and high-energy arc plasmas stably act on the inner wall of a tube body, matrix activation is improved, compact growth and binding force of a film layer are promoted, the coil magnetic field guides the plasmas to be conveyed in order, arc spots are swept on the surface of a target material in a controlled mode, and the target material quality is improved. And circumferential and axial uniform deposition of the inner wall of the pipeline with the length-diameter ratio is realized.

Description

Technical Field

[0001] This invention relates to the field of tubular component inner wall treatment technology, specifically to an arc ion plating equipment and plating method for the inner wall of a tube. Background Technology

[0002] Tubular components are widely used in nuclear energy, chemical industry, energy equipment, aerospace, and the transport of high-temperature corrosive media. They are also prevalent in military equipment; critical structural components of firing systems, such as gun barrels and cannon barrels, are essentially typical tubular components. They are typically made of high-strength alloy steel or heat-resistant alloys. During service, their inner walls must withstand extreme conditions such as high-temperature, high-pressure gas erosion, severe friction and wear, and chemical corrosion, making them prone to ablation, wear, and fatigue damage, thus affecting the accuracy and service life of weapon systems. Therefore, the service reliability of the inner walls of tubular structures is always a crucial factor limiting equipment lifespan and safety, whether in civilian or military equipment. However, due to the narrow, enclosed cavity structure, traditional surface modification techniques are difficult to apply effectively. For example, methods such as CVD, thermal spraying, and chemical treatment on the outer surface often fail to form a uniform and dense functional coating on the inner wall of tubular components. Especially for thin-walled or heat-sensitive tubular components, excessive process heat loads can cause substrate deformation and microstructure degradation, further limiting the application of related surface strengthening technologies in inner wall structures.

[0003] Arc ion plating technology, with its high ionization rate, high deposition rate, and excellent film-substrate bonding strength, is considered a potential solution to this problem. However, when applied to the inner wall of narrow cavities, it faces technical bottlenecks such as the limited size of the arc spot formed by the arc discharge, and the severe geometric constraints on the expansion direction and distribution of the generated plasma within the cavity, making it difficult to achieve uniform and comprehensive coverage of the inner wall.

[0004] The magnetron sputtering technology used in Chinese patents "CN 115961238 A coating device and coating method for the inner wall of a pipe", "CN114752902 A magnetron sputtering coating device for the inner wall of a thin pipe", and "CN 116590678 A magnetron sputtering coating device and method for the inner wall of a pipe with bias voltage" suffers from poor film adhesion and low density due to the ionization rate of deposited particles typically being only 1%-5% and the energy being weak. This makes it difficult to achieve uniform coating of the inner wall of the pipe, and the deposition rate is only 0.1-1μm / h, resulting in low efficiency. In contrast, the columnar arc ion plating technology in Chinese patent "CN104451562A An arc ion plating device for coating the inner wall of a long pipe" suffers from low target utilization, uncontrollable arc spot movement leading to poor coating uniformity and excessive local consumption of the target, and low heat dissipation efficiency restricts the deposition rate. Existing technologies cannot simultaneously achieve film quality, uniformity, and production efficiency. This invention proposes a new solution to address these problems. Summary of the Invention

[0005] In order to overcome at least one of the above-mentioned disadvantages, the present invention provides an arc ion plating device and a plating method for the inner wall of a pipe.

[0006] The objective of this invention can be achieved by adopting the following technical solution: A first aspect of this application provides an arc ion plating apparatus for the inner wall of a pipe, comprising: The coating chamber includes an upper chamber and a lower chamber. When the lower chamber moves to dock with the upper chamber, they together form a sealed vacuum coating chamber. The upper chamber is equipped with a clamping fixture for clamping and positioning the tubular workpiece to be coated at the axial position of the upper chamber. An arc-starting needle is located at the axial center of the tubular workpiece to be plated. It is used to cooperate with the target material to establish an arc discharge during the arc-starting stage. An anode is provided on the outside of the arc-starting needle to form a complete arc discharge circuit. The target material is vertically disposed inside the lower cavity and located on the outside of the tubular workpiece to be plated; A coil magnetic field is positioned between the lower and upper chambers. The magnetic field generated by the coil magnetic field penetrates the lower chamber and acts on the target area. This is used to constrain the trajectory of the arc spot during the coating process, so that the arc plasma is evenly distributed along the surface of the target material and guided to be transported along a controlled path to the inner wall of the tubular workpiece to be coated.

[0007] In one possible implementation, an arc-initiating cylinder is also included, which is disposed above the upper chamber and drives the arc-initiating needle to move up and down in the vertical direction.

[0008] In one possible implementation, a movable slide is further included, which is connected to the clamping fixture. The movable slide drives the tubular workpiece to be coated to move vertically and / or rotate around its own axis through the clamping fixture, in order to adjust the relative position of the tubular workpiece to be coated and the plasma during the coating process.

[0009] In one possible implementation, a centering device is further included. The centering device is disposed on the inner wall of the upper chamber and connected to the clamping fixture, and is used to radially constrain the clamping fixture during the vertical movement, so that the tubular workpiece to be plated remains coaxial with the arc plasma region during the axial lifting and lowering process.

[0010] In one embodiment, the upper chamber and the lower chamber are mounted and connected to each other via flanges, and the lower chamber is movable to form a sealed vacuum coating cavity together with the upper chamber when connected. The arc ion plating equipment on the inner wall of the tube further includes: A movable track is used to drive the lower chamber to move horizontally; A hydraulic lifting device is used to drive the lower chamber to rise and fall.

[0011] In one possible implementation, it further includes: A vacuum system, which is connected to the lower chamber, is used to adjust the vacuum level of the vacuum coating chamber.

[0012] In one possible implementation, the top of the upper chamber is provided with a first cooling water inlet and a first cooling water outlet, which are connected to the cooling channel of the arc-starting needle, and are used to cool the arc-starting needle during the coating process. The lower part of the lower chamber is provided with a second cooling water inlet and a second cooling water outlet, which are connected to the cooling channel of the target material and are used to cool the target material during the coating process.

[0013] A second aspect of this application provides a method for arc ion plating of the inner wall of a pipe, applicable to any of the arc ion plating equipment for the inner wall of a pipe as described in the first aspect. The plating method includes the following steps: The tubular workpiece to be coated is clamped on the clamping fixture. The lower chamber is moved horizontally to directly below the upper chamber via a movable track. Then, the lower chamber is driven to rise vertically via a hydraulic lifting device, so that the lower chamber and the upper chamber are connected and sealed to form a closed vacuum coating chamber. The vacuum system evacuates the interior of the vacuum coating chamber to the required vacuum level for the process and fills the chamber with the appropriate working gas. An electric arc discharge is established between the arc-initiating needle and the target material. Under the action of the coil magnetic field, the arc plasma bombards the target material surface uniformly, making the target material efficiently ionized. Under the guidance of the magnetic field, it is transported along a controlled path to the inner wall of the tubular workpiece to be plated to form a coating. After the coating is completed, the hydraulic lifting device drives the lower chamber to descend and moves the lower chamber horizontally out through the movable track, forming a part removal space below the upper chamber, thereby removing the tubular workpiece to be coated.

[0014] In one possible implementation, the surface to be plated on the inner wall of the tubular workpiece to be plated is ground and cleaned before clamping, and the cleaned tubular workpiece, target material and anode are loaded into the vacuum coating chamber in sequence. After the vacuum coating chamber is evacuated to the required vacuum level, the heating device is turned on. Once the temperature stabilizes at the preset temperature, cleaning gas is introduced and the gas pressure is kept stable. Slowly increase the bias voltage of the tubular workpiece to be plated, and use glow discharge to clean and heat the inner wall of the workpiece. Introduce working gas and adjust it to the process gas pressure, turn on the arc source to stabilize the target current, and at the same time adjust the bias voltage of the tubular workpiece to be coated to the coating bias voltage to carry out coating. After the coating is completed, turn off the arc source and remove the workpiece after the furnace has cooled to room temperature.

[0015] In one possible implementation, the cleaning gas includes argon and hydrogen, and the working gas includes argon and nitrogen.

[0016] The beneficial technical effects of this invention are as follows: According to this disclosure, the arc ion plating equipment and method for the inner wall of a pipe, the arc ion plating equipment for the inner wall of a pipe, by adopting a planar arc source structure and combining it with a coil magnetic field to coordinately control the arc spot movement and plasma transport process, enables highly ionized, high-energy arc plasma to stably act on the confined space of the inner wall of the pipe, thereby effectively improving the activation degree of the substrate surface, promoting the dense growth of the film layer, and improving the bonding performance between the film layer and the substrate; the controllable magnetic field generated by the coil magnetic field guides the distribution and movement direction of the plasma, which is consistent with existing methods. Unlike magnetron sputtering inner wall coating, which relies on low-ionization neutral particle line-of-sight deposition, this method utilizes the high-ionization, high-energy plasma characteristics of arc ion plating. Under the influence of a magnetic field, the arc spot is swept in an orderly manner on the surface of the planar target material. The plasma is stably transported along a controlled path to the confined space of the inner wall of the pipe. Thus, without relying on a complex cathode movement mechanism, uniform circumferential and axial deposition is achieved on the inner wall of the pipe with a length-to-diameter ratio. This significantly improves the film density, adhesion, and microstructure consistency, solving the key problems of insufficient deposition energy and poor uniformity in existing inner wall coating technologies. Attached Figure Description

[0017] The following are given by way of example and without limitation in the accompanying drawings: Figure 1 A schematic diagram of the overall structure of the arc ion plating equipment for the inner wall of the tube according to an embodiment of the present invention is shown; Figure 2 A schematic diagram of the assembly structure of the upper and lower chambers according to an embodiment of the present invention is shown; Figure 3 A schematic diagram of the cross-sectional structure of the upper chamber according to an embodiment of the present invention is shown; Figure 4 A schematic diagram of the cross-sectional structure of the lower chamber according to an embodiment of the present invention is shown; Figure 5 SEM images of the surface and cross-sectional morphology of Embodiment 1 of the present invention are shown; Figure 6 The cross-sectional elemental energy spectrum of Embodiment 1 of the present invention is shown; Figure 7 SEM images of the surface and cross-sectional morphology of Embodiment 2 of the present invention are shown; Figure 8The cross-sectional elemental energy spectrum of Embodiment 2 of the present invention is shown.

[0018] In the diagram: 1. Movable slide; 2. Arc-igniting cylinder; 3. Upper chamber; 4. Coil magnetic field; 5. Lower chamber; 6. Vacuum system; 7. Vacuum system support; 8. Movable track; 9. Equipment support; 10. Hydraulic lifting device; 31. Clamping fixture; 32. Tubular workpiece to be plated; 33. Arc-igniting needle; 34. Anode; 35. First cooling water inlet; 36. First cooling water outlet; 37. Centering device; 51. Target material; 52. Coil support; 53. Second cooling water inlet; 54. Second cooling water outlet. Detailed Implementation

[0019] In the following detailed disclosure, these embodiments are fully described with reference to the accompanying drawings. In order to enable those skilled in the art to understand and clarify the technical solution of the present invention more clearly, the embodiments described below are not limited thereto. The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings.

[0020] The first aspect of this application, as Figures 1-6 As shown, an arc ion plating device for the inner wall of a tube is provided, including a plating container, an arc-starting needle 33, a target material 51, and a coil magnetic field 4. The plating process includes an upper chamber 3 and a lower chamber 5. When the lower chamber 5 moves to align with the upper chamber 3, they together form a sealed vacuum plating cavity. A clamping fixture 31 is provided in the upper chamber 3 to clamp and position the tubular workpiece 32 to be plated along the axis of the upper chamber 3. The arc-starting needle 33 is located at the axial center of the tubular workpiece 32 to be plated and is used to cooperate with the target material 51 to establish an arc discharge during the arc-starting stage. An anode 34 is provided on the outer side to form a complete arc discharge circuit; the target material 51 is vertically arranged inside the lower chamber 5 and located on the outside of the tubular workpiece 32 to be plated; the coil magnetic field 4 is arranged between the lower chamber 5 and the upper chamber 3. The magnetic field generated by the coil magnetic field 4 penetrates the lower chamber 5 and acts on the area where the target material 51 is located. It is used to constrain the movement trajectory of the arc spot during the coating process, so that the arc plasma is evenly distributed along the surface of the target material 51 and guides the plasma to be transported along the controlled path to the inner wall of the tubular workpiece 32 to be plated.

[0021] The arc ion plating equipment for the inner wall of the pipe provided in this embodiment adopts a planar arc source structure and combines it with the coil magnetic field 4 to coordinate the movement of the arc spot and the plasma transport process. This allows the high-ionization, high-energy arc plasma to act stably on the confined space of the inner wall of the pipe, thereby effectively improving the activation degree of the substrate surface, promoting the dense growth of the film layer, and improving the bonding performance between the film layer and the substrate. The coil magnetic field 4 generates a controllable magnetic field to guide the distribution and movement direction of the plasma. Unlike the existing magnetron sputtering inner wall coating that relies on the line-of-sight deposition of low-ionization neutral particles, this method utilizes the high-ionization, high-energy plasma characteristics of arc ion plating itself. Under the action of the magnetic field, the arc spot is swept in an orderly manner on the surface of the planar target 51. The plasma is stably transported along the controlled path to the confined space of the inner wall of the pipe. Thus, without relying on a complex cathode movement mechanism, uniform circumferential and axial deposition of the inner wall of the pipe with a length-to-diameter ratio is achieved, significantly improving the film density, bonding force, and microstructure consistency. This solves the key problems of insufficient deposition energy and poor uniformity in the existing inner wall coating technology.

[0022] In this embodiment, the tube inner wall arc ion plating equipment forms a closed plating cavity by connecting the upper chamber 3 and the lower chamber 5. Combined with the clamping fixture 31, it ensures the precise positioning of the tubular workpiece 32 to be plated. The arc ignition needle 33 and the target material 51 work together to ignite the arc, and the anode 34 forms a discharge circuit to achieve efficient arc discharge. The magnetic field generated by the coil magnetic field 4 penetrates the lower chamber 5 and acts on the target material 51 area, constraining the arc spot movement trajectory, so that the plasma is evenly distributed along the surface of the target material 51 and guided to be directionally transported to the inner wall of the workpiece along the controlled path.

[0023] Understandably, this application introduces a planar arc source structure into the field of arc ion plating on the inner wall of a tube. The coil magnetic field 4 is located below the tubular workpiece 32 to be plated, and the diameter of the coil magnetic field 4 is larger than the inner diameter of the tubular workpiece 32 to be plated. The coil magnetic field 4 arranged in a circle actively constrains and guides the arc spot movement and plasma transport process. Compared with the existing inner wall coating technology, it significantly improves the deposition uniformity and consistency along the axial and circumferential directions of the inner wall of the tube, reduces the risk of film performance fluctuation, and thus overcomes the problems of low ionization rate, slow deposition rate, poor coating uniformity and insufficient operational stability in the existing inner wall coating technology.

[0024] The coil magnetic field 4 is positioned above and outside the lower chamber 5, and is mounted on the outer wall of the lower chamber 5 via a coil support 52. It generates a controllable magnetic field that can penetrate the lower chamber 5 during the coating process, constraining the arc spot to sweep orderly across the surface of the planar target 51. This allows the plasma to be transported along a controlled path to the inner wall of the pipe, achieving high-density, high-energy, and uniform deposition. Compared to magnetron sputtering, this invention utilizes the high ionization rate and high energy characteristics of arc ion plating to effectively activate the substrate surface, forming a dense and strongly bonded film, making it particularly suitable for pipes with large aspect ratios and complex inner wall shapes. The magnetic field guidance avoids circumferential unevenness caused by random arc spot movement, significantly improving the consistency of film thickness and performance. Furthermore, the efficient heat dissipation design of the planar arc source structure and the active constraint mechanism of the coil magnetic field 4 ensure that the process heat load is controllable, avoiding the problems of tissue degradation and deformation of heat-sensitive materials. The provided pipe inner wall arc ion plating equipment breaks through the bottlenecks of uniformity, density and heat-affected zone control of traditional inner wall plating technology, and achieves a long-life and highly reliable inner wall protective layer, which is suitable for high-temperature corrosive media transportation pipelines in nuclear energy, chemical industry, aerospace and other fields.

[0025] In one possible implementation, such as Figures 1-3 As shown, the inner wall arc ion plating equipment also includes an arc-starting cylinder 2, which is located above the upper chamber 3. The arc-starting cylinder 2 drives the arc-starting needle 33 to rise and fall in the vertical direction.

[0026] Among them, by setting an arc-initiating cylinder 2 above the upper chamber 3, the precise vertical lifting and lowering control of the arc-initiating needle 33 is realized. The arc-initiating cylinder 2 drives the arc-initiating needle 33 to move precisely downward during the coating start-up stage, establishing a stable arc discharge with the target material 51, ensuring that the arc-initiating process is reliable and repeatable, avoiding the uncertainty of manual operation, and significantly improving the process stability. The controlled lifting and lowering of the arc-initiating needle 33 optimizes the initial plasma distribution. The arc-initiating cylinder 2 simplifies equipment operation, reduces human error, and improves the consistency and production efficiency of coating, which is especially suitable for tubular workpieces with large length-to-diameter ratio and complex inner walls.

[0027] The inner wall arc ion plating equipment also includes an equipment support 9, which is fixedly installed on the ground to support the entire plating equipment.

[0028] In one possible implementation, such as Figures 1-3 As shown, the tube inner wall arc ion plating equipment also includes a movable slide 1, which is connected to a clamping fixture 31. The movable slide 1 drives the tubular workpiece 32 to be plated to move up and down in the vertical direction and / or rotate around its own axis through the clamping fixture 31, which is used to adjust the relative position of the tubular workpiece 32 to be plated and the plasma during the plating process.

[0029] The linkage design of the movable slide 1 and the clamping fixture 31 enables dynamic position adjustment of the tubular workpiece 32 to be coated during the coating process. The movable slide 1 drives the clamping fixture 31, allowing the workpiece to be raised and lowered in the vertical direction or rotated around its own axis, thereby flexibly changing its relative position with the plasma. This improves the coating uniformity of the inner wall of the pipe with a length-to-diameter ratio. By precisely controlling the movement of the workpiece, the uniform coverage of the plasma in the axial and circumferential directions is ensured, avoiding the problem of uneven film thickness caused by traditional static deposition, and providing a high-quality and highly consistent protective coating for the inner wall structure.

[0030] In one possible implementation, such as Figure 2 and Figure 3 As shown, the tube inner wall arc ion plating equipment also includes a centering device 37, which is disposed on the inner wall of the upper chamber 3 and connected to the clamping fixture 31. It is used to radially constrain the clamping fixture 31 during the vertical movement process, so that the tubular workpiece 32 to be plated remains coaxial with the arc plasma region during the axial lifting process.

[0031] The centering device 37 includes a telescopic rod that can extend and retract radially, ensuring that the clamping fixture 31 and the workpiece always remain coaxial with the arc plasma region, avoiding uneven coating caused by workpiece offset, improving coating quality, making the plasma evenly distributed and stably deposited along the axial direction, and eliminating film thickness differences caused by workpiece oscillation.

[0032] Among them, the centering device 37 enhances process stability, reduces the need for manual adjustments, and improves overall production efficiency.

[0033] In one possible implementation, such as Figure 1 and Figure 2 As shown, the upper chamber 3 and the lower chamber 5 are installed and connected to each other via flanges. The lower chamber 5 can be moved to form a sealed vacuum coating chamber together with the upper chamber 3 when connected. The arc ion plating equipment on the inner wall of the tube also includes a movable track 8 and a hydraulic lifting device 10. The movable track 8 is used to drive the lower chamber 5 to move horizontally, and the hydraulic lifting device 10 is used to drive the lower chamber 5 to lift.

[0034] The movable track 8 is installed on the equipment bracket 9 and is used to drive the lower chamber 5 to move precisely in the horizontal direction in order to disassemble and assemble the tubular workpiece 32 to be plated, so as to ensure that it is quickly and accurately docked with the upper chamber 3. The hydraulic lifting device 10 drives the lower chamber 5 to move vertically and provides smooth lifting control during docking, so that the lower chamber 5 can dock with the upper chamber 3. The upper chamber 3 and the lower chamber 5 are sealed and docked through the flange connection.

[0035] In one possible implementation, such as Figure 1As shown, the inner wall arc ion plating equipment also includes a vacuum system 6, which is connected to the lower chamber 5 and is used to adjust the vacuum level of the vacuum plating chamber.

[0036] The vacuum system 6 is mounted on the equipment bracket 9 via the vacuum system bracket 7 and is connected to the lower chamber 5. It can quickly pump the chamber to the high vacuum state required by the process, effectively remove air and impurity gases, avoid their interference with the coating process, improve the purity of the plasma environment, ensure the stable discharge conditions required for arc ion plating, and precisely control the vacuum degree to optimize plasma transport behavior, enhance the bonding strength between the film and the substrate, and reduce film defects.

[0037] In one possible implementation, such as Figures 2-4 As shown, the top of the upper chamber 3 is provided with a first cooling water inlet 35 and a first cooling water outlet 36, which are connected to the cooling channel of the arc-starting needle 33 and are used to cool the arc-starting needle 33 during the coating process; the bottom of the lower chamber 5 is provided with a second cooling water inlet 53 and a second cooling water outlet 54, which are connected to the cooling channel of the target material 51 and are used to cool the target material 51 during the coating process.

[0038] The first cooling water inlet 35 and the first cooling water outlet 36 at the top of the upper chamber 3 are connected to the cooling channel of the arc-starting needle 33, providing a uniform cooling path for the arc-starting needle 33. During the coating process, the cooling water circulation system continuously removes the heat generated by the arc discharge of the arc-starting needle 33, ensuring the temperature of the arc-starting needle 33 is stable and avoiding performance degradation or structural deformation due to overheating, thereby ensuring the reliability and repeatability of the arc-starting process.

[0039] The second cooling water inlet 53 and the second cooling water outlet 54 at the bottom of the lower chamber 5 are connected to the cooling channel of the target material 51, providing a uniform cooling path for the target material 51. During the coating process, the working temperature of the target material 51 is reduced, preventing the target material 51 from being damaged or the coating quality from being fluctuated due to local overheating, and significantly improving the stability of equipment operation and the consistency of coating process.

[0040] This embodiment, through a structural design combining planar target 51 with backside cooling, shortens the heat conduction path and improves the heat dissipation efficiency of target 51. This enables the equipment to operate stably under high power density conditions, improving deposition rate and overall production efficiency while ensuring coating quality. It overcomes the inherent problems of low heat dissipation efficiency and limited power density of the central cooling method of columnar arc sources. While ensuring stable and controlled arc spot, higher arc current and power density can be used, significantly improving the deposition rate and target 51 utilization. This transforms the inner wall coating process from a laboratory scale to an engineered, continuous, and high-efficiency production process, improving coating quality stability and industrial application feasibility.

[0041] During the process, the tubular workpiece 32 to be plated is first clamped onto the clamping fixture 31. The lower chamber 5 is moved horizontally to directly below the upper chamber 3 via the movable track 8. Then, the lower chamber 5 is driven vertically upward by the hydraulic lifting device 10, connecting the lower chamber 5 with the upper chamber 3 and sealing it with a flange structure, thus forming a sealed vacuum coating chamber. Subsequently, the vacuum system 6 evacuates the interior of the chamber to the required vacuum level and fills it with the appropriate working gas. An electric arc discharge is established between the arc-starting needle 33 and the target material 51. Under the action of the coil magnetic field 4, the arc plasma uniformly bombards the surface of the target material 51, efficiently ionizing the material. Guided by the magnetic field, the material is transported along a controlled path to the inner wall surface of the tubular workpiece 32 to be plated, forming a coating. During the coating process, the cooling water system continuously cools the arc-starting needle 33 and the target material 51 to ensure stable operation of the arc-starting and deposition processes. After the coating is completed, the lower chamber 5 is driven down by the hydraulic lifting device 10 and moved out horizontally via the movable track 8, forming a part removal space below the upper chamber 3, so as to conveniently remove the tubular workpiece 32 to be coated.

[0042] The second aspect of this application, as Figures 1-6 As shown, an arc ion plating method for the inner wall of a pipe is provided, applicable to any of the arc ion plating devices for the inner wall of pipes in the first aspect. The plating method includes the following steps: The tubular workpiece 32 to be plated is clamped on the clamping fixture 31. The lower chamber 5 is moved horizontally to directly below the upper chamber 3 via the movable track 8. Then, the lower chamber 5 is driven to rise vertically via the hydraulic lifting device 10, so that the lower chamber 5 and the upper chamber 3 are connected and sealed to form a closed vacuum coating chamber. The vacuum system 6 evacuates the inside of the vacuum coating chamber to the vacuum level required by the process and fills the chamber with the corresponding working gas. An electric arc discharge is established between the arc-initiating needle 33 and the target material 51. Under the action of the coil magnetic field 4, the electric arc plasma bombards the surface of the target material 51 uniformly, so that the target material 51 is efficiently ionized and transported to the inner wall of the tubular workpiece 32 to be plated under the guidance of the magnetic field to form a coating. After the coating is completed, the hydraulic lifting device 10 drives the lower chamber 5 to descend and moves the lower chamber 5 out horizontally via the movable track 8, forming a part removal space below the upper chamber 3, thereby removing the tubular workpiece 32 to be coated.

[0043] The tube inner wall arc ion plating method provided in this embodiment achieves precise docking and sealing of the lower chamber 5 and upper chamber 3 through the movable track 8 and hydraulic lifting device 10, ensuring the rapid formation and airtightness of the vacuum plating cavity, providing a stable basic environment for subsequent processes. The vacuum system 6 efficiently removes gas impurities in the cavity and precisely controls the working vacuum, creating a pure and controllable plasma environment for arc discharge. Under the active guidance of the coil magnetic field 4, the arc discharge established between the arc-initiating needle 33 and the target material 51 generates highly ionized and high-energy plasma. Under the action of the magnetic field, these plasmas bombard the surface of the target material 51 uniformly, making the target material 51 material efficiently ionized and directionally transported along a controlled path to the inner wall of the tubular workpiece 32 to be plated, achieving a uniform coating deposition with high density and strong adhesion. After the coating is completed, the hydraulic lifting device 10 and the movable track 8 cooperate to achieve the smooth descent and horizontal movement of the lower chamber 5, forming a convenient part removal space, significantly improving the coating efficiency and consistency.

[0044] Before clamping, the inner wall surface of the tubular workpiece 32 to be plated is pre-treated by grinding and cleaning. The cleaned tubular workpiece, target material 51, and anode 34 are then sequentially loaded into the vacuum coating chamber. Grinding and cleaning the surface to be plated effectively removes oxide layers, oil stains, and impurities, improving the surface activity of the substrate and providing a good foundation for subsequent coating. The sequential loading of the cleaned tubular workpiece, target material 51, and anode 34 into the vacuum coating chamber ensures accurate positioning and good contact of each component.

[0045] The process involves evacuating the vacuum coating chamber to the required vacuum level, turning on the heating device, and then filling it with cleaning gas once the temperature stabilizes at the preset temperature, while maintaining a stable gas pressure. Evacuating to the required vacuum level effectively removes air and impurities from the chamber, creating a pure environment for plasma discharge. The heating device stabilizes the chamber temperature within a preset range, activating the substrate surface and enhancing its adhesion to the coating. Filling with cleaning gas and maintaining a stable gas pressure further purifies the workpiece surface, optimizing the coating environment and improving coating quality.

[0046] In this process, the bias voltage of the tubular workpiece to be plated is gradually increased to 32, and glow discharge is used to clean and heat the inner wall of the workpiece. This gradual increase in bias voltage avoids thermal shock and electrical damage to the workpiece caused by instantaneous high voltage, ensuring a stable process. The active particles generated by the glow discharge effectively remove residual oxides and contaminants from the workpiece surface, further purifying the substrate surface. Simultaneously, the heat generated during the discharge process uniformly heats the inner wall of the workpiece, raising the substrate temperature and enhancing the adhesion and crystallization quality of subsequent plating layers.

[0047] In this process, a working gas is introduced and adjusted to the process gas pressure, the arc source is turned on, and the current of the target material 51 is stabilized. Simultaneously, the bias voltage of the tubular workpiece 32 to be coated is adjusted to the coating bias voltage for coating. Precise control of the process gas pressure ensures the uniformity and stability of the plasma discharge, which is beneficial for the efficient ionization of the target material 51. After the arc source is turned on, stable control of the current of the target material 51 ensures the consistency of the plasma density, avoiding unstable coating quality caused by current fluctuations. At the same time, precisely adjusting the workpiece bias voltage to the coating bias voltage allows high-energy ions to directionally bombard the inner wall of the workpiece under the action of the electric field, significantly improving the density, adhesion, and deposition rate of the film.

[0048] After the coating process is completed, the arc source is turned off, and the workpiece is removed after cooling to room temperature in the furnace. Turning off the arc source avoids the continuous influence of plasma discharge, preventing secondary damage or contamination of the workpiece surface. The process of cooling to room temperature in the furnace effectively avoids stress concentration and cracking caused by rapid cooling through a uniform heat conduction mechanism, maintaining the dimensional stability and structural integrity of the workpiece. Finally, the inner wall coating of the removed workpiece is intact, improving its protective performance and service life.

[0049] In one possible implementation, the cleaning gas includes argon and hydrogen, and the working gas includes argon.

[0050] Argon and hydrogen are used as cleaning gases. High-energy particles generated by glow discharge effectively remove oxides and organic contaminants from the inner wall of the workpiece, significantly improving the surface activity of the substrate.

[0051] Argon is used as the working gas. Its stable ionization characteristics ensure the uniformity and controllability of plasma discharge, providing a pure and stable working environment for subsequent arc ion plating, thereby obtaining a high-quality coating with strong adhesion and high density.

[0052] This application provides the specific steps of Embodiment 1: S1. Surface pretreatment: The inner wall of the tubular workpiece is finely polished with 2000-grit sandpaper, followed by ultrasonic cleaning with acetone, anhydrous ethanol and deionized water in sequence, each for 15 minutes. Finally, the surface residue is thoroughly removed by hot air drying. S2. Component loading: The cleaned tubular workpiece, chromium target and anode are loaded into the vacuum coating chamber in sequence; S3. Vacuum and Heating: Start the vacuum system and evacuate the chamber to 8×10⁻⁶. -4 A high vacuum state below Pa was then established; subsequently, the heating device was turned on, and when the cavity temperature stabilized at 350°C, a mixed cleaning gas of argon and hydrogen was introduced, and the gas pressure was maintained at 0.5 Pa. S4. Glow discharge cleaning: Slowly increase the bias voltage of the tubular workpiece to 800V, and use glow discharge to clean and heat the inner wall of the workpiece. The processing time is 15 minutes. S5. Coating process: Argon gas is introduced as the working gas and the gas pressure is adjusted to 1.5Pa; the arc source is turned on and the target current is controlled to be stable at 60A. At the same time, the workpiece bias voltage is adjusted to 50V to perform chromium film deposition. The coating time is 30min. S6. Post-treatment: After the coating is completed, turn off the arc source and remove the workpiece after it has cooled to room temperature in the furnace.

[0053] In Example 1, argon is used as the working gas to deposit a chromium film at a substrate temperature of 350°C. The argon environment ensures the directional bombardment of chromium ions with a high ionization rate, forming a dense chromium layer that is firmly bonded to the substrate. This effectively improves the corrosion resistance and wear resistance of the inner wall of the workpiece. The 800V glow discharge cleaning stage fully activates the substrate surface, eliminates residual contaminants, provides a clean substrate for subsequent coating, and reduces film defects. This method is suitable for scenarios with high requirements for the protection of pure metals, such as the inner wall of chemical pipelines, and avoids the risk of deformation of heat-sensitive materials at relatively low temperatures.

[0054] In this case, the inner wall of the tubular workpiece obtained through step 1 was prepared with a chromium coating on its surface and cross-section, as shown in Example 1. Figure 5 As shown, the cross-sectional elemental energy spectrum is as follows: Figure 6 As shown, the coating surface is continuous and dense, exhibiting typical micron-level droplet characteristics of arc ion plating, and no obvious pores or cracks are observed, indicating that the discharge deposition process is stable. Figure 5 The cross-sectional SEM image shows that the interface between the coating and the substrate is clear and tightly bonded, with no peeling or gaps. The coating thickness is uniform, approximately 3 μm.

[0055] This application provides the specific steps of Embodiment 2: S1. Surface pretreatment: Same as in Example 1, the inner wall of the tubular workpiece is polished with 2000-grit sandpaper, and then ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 15 minutes in sequence, and finally dried with hot air. S2. Component loading: The cleaned tubular workpiece, chromium target and anode are loaded into the vacuum coating chamber in sequence; S3. Vacuum and Heating: Start the vacuum system and evacuate to 8×10 -4 When the pressure is below Pa, turn on the heating device to stabilize the cavity temperature at 400℃, and fill it with a mixed cleaning gas of argon and hydrogen to maintain a pressure of 0.5 Pa. S4. Glow discharge cleaning: Slowly increase the workpiece bias voltage to 800V, perform glow discharge cleaning and heating for 15 minutes; S5. Coating process: Introduce a mixed working gas of nitrogen and argon, and adjust the gas pressure to 1.2Pa; turn on the arc source, control the target current to stabilize at 50A, adjust the workpiece bias voltage to 70V, and perform chromium nitride film deposition for 30min. S6. Post-treatment: After the coating is completed, turn off the arc source and remove the workpiece after it has cooled to room temperature in the furnace.

[0056] In Example 2, a mixture of nitrogen and argon was used to deposit a chromium nitride film at a substrate temperature of 400°C. The introduction of nitrogen promoted the reaction between chromium and nitrogen to form chromium nitride, which significantly enhanced the hardness and chemical stability of the film, making it particularly suitable for high-temperature oxidizing environments, such as the inner walls of aerospace components. The relatively high substrate temperature of 400°C further promoted interfacial diffusion and improved the bonding strength between the film and the substrate. At the same time, hydrogen-assisted cleaning enhanced surface purity and reduced porosity. Furthermore, the gas ratio could be adjusted to flexibly control the composition and performance of the film, meeting diverse operating conditions and improving adaptability.

[0057] In this example, the inner wall of the tubular workpiece obtained through step 2 was coated with a chromium nitride (CrN) coating. The surface and cross-section are shown below. Figure 7 As shown, the cross-sectional elemental energy spectrum is as follows: Figure 8 As shown, the coating surface maintains good continuity and density, with several micron-sized molten droplet particles distributed on the surface, and no obvious cracks or pore defects. Combined with... Figure 7 The SEM images of the cross-sectional morphology show that the coating is tightly bonded to the substrate, with a clear interface and no peeling, and the coating thickness is approximately 6 μm. The EDS line scan spectrum shows that the signal intensities of chromium (Cr) and nitrogen (N) elements are both maintained at a high level, and their distribution ranges highly overlap, confirming the successful deposition of a uniform chromium nitride compound coating on the inner wall of the tube.

[0058] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0059] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0060] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0062] In view of the detailed description above, these and other changes can be made to these embodiments, and this written description includes embodiments of the best mode that disclose the invention. The patent scope of the invention is defined by the claims, which are not limited by this disclosure. The scope of protection of the invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the invention disclosed herein, based on the technical solutions and concepts of the invention, are within the scope of protection of the invention.

Claims

1. An arc ion plating device for the inner wall of a pipe, characterized in that, include: The coating container includes an upper chamber (3) and a lower chamber (5). When the lower chamber (5) moves to dock with the upper chamber (3), they together form a sealed vacuum coating cavity. The upper chamber (3) is provided with a clamping fixture (31) for clamping and positioning the tubular workpiece (32) to be coated at the axial position of the upper chamber (3). Arc-starting needle (33) is located at the axial center of the tubular workpiece (32) to be plated, and is used to cooperate with the target material (51) to establish an arc discharge during the arc-starting stage. An anode (34) is provided on the outside of the arc-starting needle (33) to form a complete arc discharge circuit. The target material (51) is vertically disposed inside the lower chamber (5) and located outside the tubular workpiece (32) to be plated; The coil magnetic field (4) is located between the lower chamber (5) and the upper chamber (3). The magnetic field generated by the coil magnetic field (4) penetrates the lower chamber (5) and acts on the area where the target material (51) is located. It is used to constrain the movement trajectory of the arc spot during the coating process, so that the arc plasma is evenly distributed along the surface of the target material (51) and guides the plasma to be transported along the controlled path to the inner wall of the tubular workpiece (32) to be coated.

2. The pipe inner wall arc ion plating equipment according to claim 1, characterized in that, It also includes an arc-initiating cylinder (2), which is located above the upper chamber (3). The arc-initiating cylinder (2) drives the arc-initiating needle (33) to rise and fall in the vertical direction.

3. The pipe inner wall arc ion plating equipment according to claim 1, characterized in that, It also includes a movable slide (1), which is connected to the clamping fixture (31). The movable slide (1) drives the tubular workpiece (32) to be coated to move up and down in the vertical direction and / or rotate around its own axis through the clamping fixture (31), which is used to adjust the relative position of the tubular workpiece (32) to be coated and the plasma during the coating process.

4. The pipe inner wall arc ion plating equipment according to claim 3, characterized in that, It also includes a centering device (37), which is disposed on the inner wall of the upper chamber (3) and connected to the clamping fixture (31) for radial constraint of the clamping fixture (31) during vertical movement, so that the tubular workpiece (32) to be plated remains coaxial with the arc plasma region during axial lifting and lowering.

5. The pipe inner wall arc ion plating equipment according to claim 1, characterized in that, The upper chamber (3) and the lower chamber (5) are installed and connected to each other via flanges. The lower chamber (5) can be moved to form a sealed vacuum coating cavity together with the upper chamber (3) when connected. The inner wall arc ion plating equipment also includes: A movable track (8) is used to drive the lower chamber (5) to move horizontally; A hydraulic lifting device (10) is used to drive the lower chamber (5) to rise and fall.

6. The arc ion plating equipment for the inner wall of a pipe according to claim 5, characterized in that, Also includes: A vacuum system (6) is connected to the lower chamber (5) and is used to adjust the vacuum level of the vacuum coating chamber.

7. The arc ion plating equipment for the inner wall of a pipe according to claim 1, characterized in that, The top of the upper chamber (3) is provided with a first cooling water inlet (35) and a first cooling water outlet (36), which are connected to the cooling channel of the arc-starting needle (33) and are used to cool the arc-starting needle (33) during the coating process. The lower chamber (5) is provided with a second cooling water inlet (53) and a second cooling water outlet (54) at its bottom, which are connected to the cooling channel of the target material (51) and are used to cool the target material (51) during the coating process.

8. A method for arc ion plating of the inner wall of a pipe, characterized in that, The arc ion plating equipment for the inner wall of a pipe as described in any one of claims 1-7, the plating method comprising the following steps: The tubular workpiece to be coated is clamped on the clamping fixture. The lower chamber is moved horizontally to directly below the upper chamber via a movable track. Then, the lower chamber is driven to rise vertically via a hydraulic lifting device, so that the lower chamber and the upper chamber are connected and sealed to form a closed vacuum coating chamber. The vacuum system evacuates the interior of the vacuum coating chamber to the required vacuum level and fills the chamber with the appropriate working gas. An electric arc discharge is established between the arc-initiating needle and the target material. Under the action of the coil magnetic field, the arc plasma bombards the target material surface uniformly, making the target material efficiently ionized. Under the guidance of the magnetic field, it is transported along a controlled path to the inner wall of the tubular workpiece to be plated to form a coating. After the coating is completed, the hydraulic lifting device drives the lower chamber to descend and moves the lower chamber horizontally out through the movable track, forming a part removal space below the upper chamber, thereby removing the tubular workpiece to be coated.

9. The method for arc ion plating on the inner wall of a pipe according to claim 8, characterized in that, Before clamping, the inner wall of the tubular workpiece to be plated is ground and cleaned for pretreatment. The cleaned tubular workpiece, target material and anode are then loaded into the vacuum coating chamber in sequence. After the vacuum coating chamber is evacuated to the required vacuum level, the heating device is turned on. Once the temperature stabilizes at the preset temperature, cleaning gas is introduced and the gas pressure is kept stable. Slowly increase the bias voltage of the tubular workpiece to be plated, and use glow discharge to clean and heat the inner wall of the workpiece. Introduce working gas and adjust it to the process gas pressure, turn on the electric arc source to stabilize the target current, and at the same time adjust the bias voltage of the tubular workpiece to be coated to the coating bias voltage to carry out coating. After the coating is completed, turn off the arc source and remove the workpiece after the furnace has cooled to room temperature.

10. The method for arc ion plating on the inner wall of a pipe according to claim 9, characterized in that, The cleaning gas includes argon and hydrogen, and the working gas includes argon, nitrogen, oxygen, and hydrocarbon gases.

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