Powder coating device and method of use thereof

Abstract

The present invention discloses a powder coating device and a method for using the same, belonging to the technical field of powder coating materials. The powder coating device includes a vacuum chamber and a control system. The vacuum chamber is provided with a powder processing bin, a powder bin, a circulation component, and an emission source. The bottom of the powder processing bin is detachably connected to the top of the powder bin. The circulation component includes a powder circulation pipeline and a circulation pump provided on the powder circulation pipeline. The two ends of the powder circulation pipeline are respectively connected to the top of the powder processing bin and the bottom of the powder bin. The emission source is provided on the inner wall of the vacuum chamber. A window is provided on the side wall of the powder processing bin to allow the particle flow of the emission source to pass through. A movable shutter is provided at the window. The control system is electrically connected to the emission source, the circulation pump, and the movable shutter. The present invention can realize the use of a physical vapor deposition method to coat a protective and modified layer on the surface of fine powder and ultrafine metal powder, thereby solving the problem of easy loss of fine powder and circulation of processed powder during vacuuming.

Description

Technical Field

[0001] The present invention relates to the technical field of powder coating materials, in particular to a device for powder coating using a physical vapor deposition method and a method for using the device. Background Art

[0002] With the advancement of science and technology and the development of the materials industry, powder surface coating modification technology has gradually been applied to all aspects of the industry. The principle of powder coating modification is to uniformly introduce one or more other components onto the surface of powder particles, forming a deposition layer of a certain thickness through chemical reaction or physical adsorption, thereby changing the surface characteristics of the powder or giving the powder new properties.

[0003] In the existing technology, powder coating modification technology mainly includes two categories: liquid phase method and vapor phase method. The former includes mechanochemical method, liquid phase precipitation method, sol-gel method, chemical plating and other methods, and the latter mainly refers to physical vapor deposition method and chemical vapor deposition method. The mechanochemical method is a method that activates the powder and surface coating modifier by means of strong mechanical stirring, impact, shear grinding and other effects, and allows the particles to react with the modifier to coat it on the outer surface of the powder particles. The mechanochemical method has the advantages of short processing time, easy process control, and continuous batch production. However, it also has disadvantages such as the crystal form of inorganic particles is destroyed during the mechanical treatment process and the coating is uneven. The liquid phase deposition method, also called the precipitation method, is a method that utilizes the tendency of the modifier in the liquid supersaturated system to deposit and precipitate on the surface of the modified particles, thereby forming a coating on the powder particles. Precipitation methods are widely used due to their controllable process and uniform coating, making them particularly suitable for inorganic coating of ultrafine powders. However, their drawbacks include the requirement for a very low concentration of the coated particles, which can easily lead to agglomeration. Furthermore, traditional liquid-phase deposition methods suffer from high energy consumption, significant material loss, and the tendency for particles to aggregate and grow during liquid-solid separation and drying. The sol-gel method involves first dissolving a modifier precursor in water or an organic solvent to form a uniform solution. The solute and solvent undergo hydrolysis or alcoholysis to produce a sol of the modifier or its precursor. The pretreated coated particles are then mixed with the sol to uniformly disperse the particles throughout the sol. The sol is then treated to transform into a gel, and the gel is finally calcined at high temperature to produce a powder coated with the modifier. While the sol-gel method produces powders with high purity and good chemical uniformity, the process is complex and often requires calcination, which can alter the powder's crystal form and internal structure. The application of chemical plating in powder surface coating modification is to use the metal ions in the plating solution to be reduced by the reducing agent under the action of catalyst to form metal particles on the powder surface, and then separate the powder from the plating solution and dry it. The chemical plating process is relatively mature, and the coating layer thickness is relatively uniform, but there are also problems such as the coating reaction is difficult to control, there is a certain adhesion phenomenon between the coated particles (caused by the magnetic stirring magnetic field), the plating solution is easy to decompose and the waste liquid needs to be treated, and the uniform coating of the powder is controlled by its dispersion effect. The vapor deposition method is to deposit the coating material or the components containing the coating material on the powder surface in the form of gas through physical or chemical reactions to obtain a dense, uniform, and compositionally controllable film layer. It has the outstanding advantages of simple process, good coating uniformity, and strong controllability.

[0004] Physical vapor deposition (PVD) is a common method in powder coating and modification applications. It involves using physical methods to vaporize the surface of a material source (solid or liquid) into gaseous atoms or molecules, or partially ionize them into ions, under vacuum conditions. These molecules are then deposited on the powder surface via low-pressure gas (or plasma) to create a dense, uniform film with controlled composition. However, PVD requires a relatively high vacuum environment, and the process is subject to problems such as easy powder loss and low efficiency, which have limited its further application in the field of powder coating. Summary of the Invention

[0005] In view of this, the present invention provides a device for powder coating using physical vapor deposition. The powder coating device can coat a protective and modified layer on the surface of fine powder and ultrafine metal powder, thereby solving the problem of easy loss of fine powder and circulation of processed powder during vacuuming.

[0006] The present invention is achieved by the following technical solutions:

[0007] A powder coating device includes a vacuum chamber and a control system, wherein a powder processing bin, a powder bin, a circulation component and an emission source are provided in the vacuum chamber; the bottom of the powder processing bin is detachably connected to the top of the powder bin; the circulation component includes a powder circulation pipeline and a circulation pump provided on the powder circulation pipeline, and the two ends of the powder circulation pipeline are respectively connected to the top of the powder processing bin and the bottom of the powder bin; the emission source is provided on the inner wall of the vacuum chamber, and a window allowing the emission source particle flow to pass through is opened on the side wall of the powder processing bin, and a movable shutter is provided at the window; the control system is electrically connected to the emission source, the circulation pump and the movable shutter respectively.

[0008] Compared with the prior art, the present invention has at least the following beneficial effects:

[0009] The present invention adds a powder processing chamber to the vacuum chamber, and a window and an openable shutter are provided on the side wall of the powder processing chamber. When the powder processing chamber is evacuated, the opening and closing of the shutter is controlled by a control system, thereby controlling the opening / closing of the window. After the ion bombardment, cleaning process, and subsequent ion plating and sputtering coating are stable, the window is opened as needed and closed again before stopping, thereby solving the problem of powder loss during vacuuming in the prior art. In addition, the present invention also provides a powder circulation pipeline and a circulation pump. The powder circulation pipeline connects the powder processing chamber with the outside of the powder chamber to form a circulation channel. By controlling the opening and closing of the circulation pump, the powder is controlled to circulate between the powder chamber and the powder processing chamber, so that the powder uniformly passes through the particle flow emitted by the emission source, and a uniform coating layer is formed on the surface of the powder material by physical vapor deposition. Furthermore, the vacuum chamber also includes a heater, which is evenly arranged around the outside of the powder processing chamber. The heater is arranged around the outside of the powder processing chamber to ensure uniform heating of the powder processing chamber.

[0010] Furthermore, a powder separator is provided on the top of the powder processing bin, and the powder is evenly dispersed after passing through the powder separator from the powder circulation pipeline and then falls into the powder processing bin. The powder separator is provided on the top of the powder processing bin so that the powder passing through the powder separator is evenly distributed when falling in the powder processing bin.

[0011] Furthermore, the circulation component further includes two control valves, which are respectively arranged on the powder circulation pipelines on both sides of the circulation pump.

[0012] Furthermore, a plurality of emission sources are symmetrically arranged along the central axis of the vacuum chamber on the same horizontal plane, and the direction of the particle flow emitted axially forms a downward inclination angle of 5° to 85° with the normal line of the vacuum chamber wall.

[0013] Furthermore, the position of the window on the side wall of the powder processing chamber is not higher than the position of the emission source on the inner wall of the vacuum chamber.

[0014] Furthermore, the central axis of the powder processing chamber coincides with the central axis of the vacuum chamber, ensuring that the particle flow emitted by the emission source can pass through the window as much as possible to contact the powder.

[0015] Furthermore, the emission source is an arc source or a magnetron cathode. The device is used to prepare powder materials with a coating structure by a physical vapor deposition method, which includes sputtering and ion plating. Sputtering is usually magnetron sputtering, and ion plating is usually arc ion plating.

[0016] Furthermore, the bottom of the powder silo and the powder circulation pipeline are tightly connected via a corrosion-resistant part, and the corrosion-resistant part is made of PTFE material.

[0017] Furthermore, the circulation pump is a corrosion-resistant pump, which can work under vacuum or negative pressure, and the power of the circulation pump is adjustable, which can control the powder flow rate to be 0.01 to 50 g / s.

[0018] The present invention also provides an operating method of a powder coating device, which comprises the following steps:

[0019] S1: Vacuuming: Control the movable shutter to close the window on the side wall of the powder processing chamber, start the circulation pump and control valve, control the powder to be processed to run at the minimum circulation speed, and vacuum the vacuum chamber;

[0020] S2: Cleaning the powder to be processed: Adjust the circulation speed of the powder to be processed to an appropriate value, introduce argon gas into the vacuum chamber, apply an appropriate bias voltage to the powder processing chamber, form a stable plasma, open the movable shutter of the side wall window of the powder processing chamber, clean the powder to be processed, and then close the window;

[0021] S3: Heating temperature adjustment: Turn on the heating device in advance and adjust it to the predetermined temperature as required;

[0022] S4: Deposition of protective and modified thin films: Adjust and maintain the working gases including argon to an appropriate flow rate, adjust the emission source to work in the preset state, open the movable shutter of the side wall window of the powder processing chamber again, and maintain the powder flowing at an appropriate flow rate in the powder processing chamber;

[0023] S5: After the powder to be processed is kept circulating in the powder processing chamber for a certain period of time, the circulation pump, the window on the wall of the powder processing chamber, the heater and the power supply of the emission source are turned off in sequence. The vacuum system continues to work for 0.5-2 hours. After the side wall of the powder processing chamber cools to room temperature, the vacuum chamber is opened, the connecting parts between the powder processing chamber and the powder chamber are separated, and the processed powder is taken out.

[0024] This device and its use method can solve the problems of circulation and easy loss of (ultra) fine metal powders under vacuum conditions. It can be used to uniformly deposit pure metals, alloys, and metal nitrides, oxides, carbides, carbonitride films or composite films of the above products with a thickness of 20nm-2μm on the surface of powders with an average particle size of 1.0-10.0μm, and has batch processing capabilities.

[0025] In addition, through composition adjustment and subsequent heat treatment, an alloy layer can be formed at the interface between the metal coating and the metal powder. On the basis of improving the corrosion resistance, high temperature resistance, acid resistance, alkali resistance and other properties of the original metal powder, the ability to regulate the electromagnetic properties of the metal powder surface can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a powder coating device of the present invention.

[0027] Among them, the accompanying drawings illustrate: 1. Vacuum chamber; 11. Powder processing chamber; 12. Powder silo; 13. Heater; 14. Powder separator; 15. Emission source; 16. Powder circulation pipeline; 17. Circulation pump; 18. Control valve; 111. Window. DETAILED DESCRIPTION

[0028] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below with reference to the accompanying drawings and preferred embodiments. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0029] Unless otherwise defined, all technical terms used below have the same meanings as those commonly understood by those skilled in the art. The technical terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0031] like Figure 1As shown, this embodiment provides a powder coating device and a process in which the device is used for preparing a powder material with a coating layer structure by arc ion plating in a physical vapor deposition method. The device includes a vacuum chamber 1 and a control system. A powder processing bin 11 and a powder bin 12 are vertically arranged inside the vacuum chamber 1. The powder processing bin 11 is detachably connected and arranged on the top of the powder bin 12, and the top of the powder processing bin 11 is connected to the bottom of the powder bin 12 through a powder circulation pipeline 16. A circulation pump 17 is provided on the powder circulation pipeline 16, and control valves 18 are respectively provided on the powder circulation pipeline 16 on both sides of the circulation pump 17; an emission source 15 is provided on the inner wall of the vacuum chamber 1, and a window 111 is provided at a position on the side wall of the powder processing bin 11 corresponding to the emission source 15 in a straight line, and an openable movable shutter is provided on the window 111; the control system is electrically connected to the circulation pump 17, the movable shutter, and the emission source 15 respectively to control the opening and closing of the circulation pump 17, the movable shutter and the emission source 15. During the vacuuming process, the device controls the movable shutter to close the window 111 to reduce powder loss; after the vacuuming is completed, the circulation pump 17 is turned on to transport the powder to the top of the powder processing bin 11, and then the powder falls from the top of the powder processing bin 11 in the form of free fall, and then the movable shutter is opened. During the falling process, the powder passes through the window 111 position, and the particles emitted by the emission source 15 pass through the window 111 and irradiate the powder, completing the powder cleaning and the deposition of the thin film material.

[0032] Among them, the powder processing chamber 11 can be an axially symmetrical geometric body including a cylinder, a cuboid, and a cube, wherein the axis coincides with the central axis of the vacuum chamber 1; and a heater 13 is evenly arranged around the periphery of the powder processing chamber 11, and the control system is electrically connected to the heater 13 to control the temperature of the powder processing chamber 7.

[0033] A plurality of emission sources 15 are arranged at different horizontal heights on the inner wall of the vacuum chamber 1, and six emission sources 15 are arranged on the same horizontal plane, and the six emission sources 15 are evenly distributed on the inner wall of the vacuum chamber 1 with the axis of the vacuum chamber 1 as the center; the size of the window 111 on the side wall of the powder processing chamber 11 is determined according to the size of the configured emission source 15 and the distance between the emission source 15 and the window 111, ensuring that the particle flow emitted by the emission source 15 can cover the window 111, and the horizontal height of the window 111 is not higher than the horizontal height of the emission source 15 on the inner wall of the vacuum chamber 1; at the same time, the direction of the particle flow emitted by the axial direction of the emission source 15 is inclined downward at 5°-85° with the normal to the wall of the vacuum chamber 1, ensuring that the particle flow emitted by the emission source 15 is irradiated to the powder surface as much as possible.

[0034] Based on the above scheme, the process of preparing powder materials with a coating structure by arc ion plating in this device is as follows:

[0035] (1) Vacuuming: remotely control the movable shutter to close the window 111 on the side wall of the powder processing chamber 11, start the circulation pump 17 and the control valve 18, control the powder to be processed to run at the minimum circulation speed, start the vacuum unit of the physical vapor deposition system, and evacuate to the background vacuum;

[0036] (2) Cleaning the powder to be processed: adjust the circulation speed of the powder to be processed to an appropriate value, introduce argon gas into the vacuum chamber 1, apply an appropriate bias voltage to the powder processing chamber 11, select an arc source as the emission source 15, and after forming a stable arc, open the movable shutter of the window 111 on the side wall of the powder processing chamber 11, clean the powder to be processed for 1-20 minutes, and then close the window 111;

[0037] (3) Heating temperature adjustment: the heater 13 is turned on in advance and adjusted to a predetermined temperature as required;

[0038] (4) Deposition of protective and modified thin films: Adjust and maintain the working gas including argon gas to an appropriate flow rate, adjust the emission source 15 to work in a preset state, open the movable shutter of the side wall window 111 of the powder processing chamber 11 again, and maintain the powder flowing at an appropriate flow rate in the powder processing chamber 11;

[0039] (5) After the powder to be treated is kept in the powder treatment chamber 11 to deposit a protective and modified film for a preset time, the circulating pump 17, the powder treatment chamber side wall window 111, the heater 13 and the emission source 15 are turned off, and the vacuum system continues to work for 0.5-2 hours. After the side wall of the powder treatment chamber 11 cools to room temperature, the system is turned off and the vacuum chamber is deflated; finally, the vacuum chamber is opened, the connection between the powder chamber 12 and other parts is separated, and the treated powder is taken out.

[0040] In other embodiments, if a magnetron sputtering method is used for powder film coating, a sputtering target can be installed on the inner wall of the vacuum chamber 1 as an emission source 15. After argon gas is introduced into the vacuum chamber 1, a suitable bias voltage is added to the powder processing chamber 11. Under the action of the electric field, Ar ions bombard the target surface to generate sputtered particles, which are deposited on the powder surface to form a thin film.

[0041] Based on the above-mentioned usage method, the device closes the window during the vacuuming process, which can effectively avoid the powder loss caused by the vacuuming process. Then, the powder is controlled to circulate in the powder processing chamber 11, and a physical vapor deposition method such as arc ion plating or magnetron sputtering is used to complete the uniform coating of the thin film on the surface of the powder material, effectively improving the efficiency. At the same time, when the powder passes through the window 111, the particle flow such as plasma / atomic clusters emitted by the corresponding arc source / target material and the negative pressure of the vacuum chamber-powder processing chamber are offset, eliminating the powder loss caused by this. In addition, through composition adjustment and subsequent heat treatment, the device can also form an alloy layer at the interface between the metal coating layer and the metal powder, further improving the ability to control the electromagnetic properties of the metal powder surface on the basis of improving the corrosion resistance, high temperature resistance, acid resistance, alkali resistance and other properties of the original metal powder.

[0042] In the embodiment, a powder separator 14 is provided at the top of the powder processing bin 11. After being processed by the powder separator 14, the powder is evenly distributed when it falls from the top of the powder processing bin 11. As can be seen from the above processing process, the powder to be processed is sent from the bottom of the powder bin 12 to the top of the powder processing bin 11 through the circulation pump 17 and the powder circulation pipeline 16 via the powder separator 14. The powder to be processed falls evenly from the top in the form of free fall. When passing through the window 111, it is cleaned by plasma bombardment and thin film material is deposited, and then falls to the bottom of the powder bin 12, thus forming a powder processing loop and circulation.

[0043] In one embodiment, a plurality of temperature measuring devices may be provided inside the powder processing chamber 11 to monitor the internal temperature of the powder processing chamber 11 to reach a set temperature for normal thin film deposition when the heater 13 heats the powder processing chamber 11 .

[0044] In one embodiment, the circulation pump 17 is a corrosion-resistant pump that can operate under vacuum or negative pressure. The power of the circulation pump 11 is adjustable and can control the powder flow rate to be 0.01 to 50 g / s.

[0045] In one embodiment, the powder bin 12 and the powder circulation pipeline 16 are connected by corrosion-resistant parts to ensure the fluidity of the powder while preventing chemical reactions therewith. Furthermore, the corrosion-resistant parts are made of polytetrafluoroethylene (PTFE) material.

[0046] The various technical features in the above embodiments can be combined arbitrarily as long as there is no conflict or contradiction between the combinations of features. However, due to space limitations, they are not described one by one.

[0047] The above descriptions are only some embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. Those skilled in the art should be aware that any solutions obtained by equivalent substitutions and obvious changes made using the contents of the present invention specification should be included in the protection scope of the present invention.

Claims

1. A powder coating device, characterized in that: The invention comprises a vacuum chamber and a control system, wherein the vacuum chamber is provided with a powder processing bin, a powder bin, a circulation component and an emission source; the bottom of the powder processing bin is detachably connected to the top of the powder bin; the circulation component comprises a powder circulation pipeline and a circulation pump arranged on the powder circulation pipeline, and the two ends of the powder circulation pipeline are respectively connected to the top of the powder processing bin and the bottom of the powder bin; the emission source is arranged on the inner wall of the vacuum chamber, and a plurality of emission sources are symmetrically arranged along the central axis of the vacuum chamber on the same horizontal plane, and the direction of the particle flow emitted by the axial direction is downwardly inclined at an angle of 5° to 85° with the normal of the vacuum chamber wall surface; a window is provided on the side wall of the powder processing bin to allow the particle flow of the emission source to pass through, and the particle flow emitted by the emission source can cover the window, the position of the window on the side wall of the powder processing bin is not higher than the position of the emission source on the inner wall of the vacuum chamber, and a movable shutter is provided at the window; the control system is electrically connected to the emission source, the circulation pump and the movable shutter respectively.

2. A powder coating device according to claim 1, characterized in that: The vacuum chamber further includes a heater, which is evenly arranged around the outside of the powder processing chamber.

3. A powder coating device according to claim 1, characterized in that: A powder separator is provided on the top of the powder processing bin, and the powder passes through the powder separator from the powder circulation pipeline and is evenly dispersed before falling into the powder processing bin.

4. A powder coating device according to claim 1, characterized in that: The circulation component further includes two control valves, which are respectively arranged on the powder circulation pipelines on both sides of the circulation pump.

5. A powder coating device according to claim 1, characterized in that: The central axis of the powder processing bin coincides with the central axis of the vacuum chamber.

6. A powder coating device according to claim 1, characterized in that: The emission source is an arc source or a magnetron cathode.

7. A powder coating device according to claim 1, characterized in that: The bottom of the powder bin and the powder circulation pipeline are tightly connected via a corrosion-resistant part, and the corrosion-resistant part is made of PTFE material.

8. A method for using the powder coating device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Vacuuming: After controlling the movable shutter to close the window on the side wall of the powder processing chamber, the circulation pump and control valve are turned on to control the powder to be processed to run at the minimum circulation speed and vacuum the vacuum chamber; S2: Cleaning the powder to be processed: Adjust the circulation speed of the powder to be processed to an appropriate value, introduce argon gas into the vacuum chamber, apply an appropriate bias voltage to the powder processing chamber, form a stable plasma, open the movable shutter of the side wall window of the powder processing chamber, clean the powder to be processed, and then close the window; S3: Heating temperature adjustment: Turn on the heating device in advance and adjust it to the predetermined temperature as required; S4: Deposition of protective and modified thin films: Adjust and maintain the working gases including argon to an appropriate flow rate, adjust the emission source to work in the preset state, open the movable shutter of the side wall window of the powder processing chamber again, and maintain the powder flowing at an appropriate flow rate in the powder processing chamber; S5: After the powder to be processed is kept circulating in the powder processing chamber for a certain period of time, the circulation pump, the window on the wall of the powder processing chamber, the heater and the power supply of the emission source are turned off in sequence. The vacuum system continues to work for 0.5-2 hours. After the side wall of the powder processing chamber cools to room temperature, the vacuum chamber is opened, the connecting parts between the powder processing chamber and the powder chamber are separated, and the processed powder is taken out.

Images