Metal powder magnetron sputter continuous coating apparatus and method

Abstract

This invention relates to the field of powder surface modification technology, and discloses a continuous coating device and method for metal powder by magnetron sputtering, comprising: an electric field oscillation discrete section for causing metal powder particles to reciprocate oscillating motion under the action of an electric field force, thereby achieving high discreteness of the metal powder material and imparting initial kinetic energy; a differential pumping transition chamber connected downstream of the electric field oscillation discrete section; a magnetron sputtering deposition section connected downstream of the differential pumping transition chamber for depositing a coating layer on the surface of the metal powder particles by magnetron sputtering; and a particle circulation section connected between the magnetron sputtering deposition section and the electric field oscillation discrete section for returning the partially coated metal powder material to the electric field oscillation discrete section for multiple circulation processes; through the synergistic integration of the electric field oscillation discrete section, the differential pumping transition chamber, the magnetron sputtering deposition section, and the particle circulation section, a closed-loop processing flow of discrete-transport-deposition-circulation is formed.

Description

Technical Field

[0001] This invention relates to the field of powder surface modification technology, and in particular, to a continuous coating apparatus and method for metal powder by magnetron sputtering. Background Technology

[0002] Metal powders, especially micron-sized aluminum powder and its alloy powders, have broad application prospects in new energy materials, additive manufacturing, composite materials, and chemical catalysis due to their high reactivity, high specific surface area, and excellent physicochemical properties. However, during storage and processing, micron-sized metal powders are highly susceptible to surface passivation due to their high surface energy, readily reacting with oxygen and moisture in the environment, or agglomerating due to van der Waals forces and electrostatic adsorption between particles. This severely affects their dispersibility, flowability, and performance stability in subsequent applications. Therefore, constructing a dense, uniform, and strongly bonded functional coating layer on the surface of metal powders is a key technical means to improve their environmental adaptability and performance.

[0003] Physical vapor deposition (PVD), especially magnetron sputtering, is widely recognized as an ideal surface modification technology due to its advantages such as low deposition temperature, high film purity, good density, and controllable composition. In recent years, the industry has begun to explore applying magnetron sputtering to the surface coating of powder particles, aiming to utilize high-energy particle bombardment and deposition mechanisms to grow coating layers in situ on micron-sized powder surfaces. However, transforming traditional planar magnetron sputtering technology into a continuous processing technology suitable for flowing powders faces the following pressing technical challenges: First, powder dispersion is difficult. In low-pressure or high-vacuum environments, the distance between micron-sized metal powder particles decreases, and the long-range van der Waals forces and short-range electrostatic adsorption forces are significantly enhanced, causing the particles to easily agglomerate into "pseudo-large particles." Traditional mechanical stirring or vibration dispersion methods are difficult to seal in a vacuum environment, have poor reliability, and are prone to introducing metal impurities; while simple gas fluidization is prone to particle collision and breakage or the generation of dust clouds, which cannot ensure that the powder is in a highly dispersed single-particle state before entering the deposition zone, thus leading to uneven coating thickness or leakage.

[0004] Second, there is a conflict between the vacuum environment and powder delivery. Magnetron sputtering deposition processes require extremely high vacuum levels to be maintained around the target (typically around 10). -2 Pa to 10 -3 To reduce the interference of impurity gases on the film quality, the gas flow rate is on the order of Pa (in milliseconds). However, conventional powder pneumatic conveying requires a large amount of carrier gas, which is inherently incompatible with a high vacuum environment. How to allow powder to pass continuously while effectively preventing the transport gas from entering the high vacuum deposition chamber is the core obstacle to building a continuous production line.

[0005] Third, the coating thickness is difficult to control precisely. For micron-sized powders, it is often difficult to obtain a coating layer of sufficient thickness by passing through the magnetron sputtering zone in a single pass, while an excessively long deposition path will lead to a sharp increase in equipment costs, making it impossible to meet the requirements of product consistency for industrial production.

[0006] In summary, how to achieve pollution-free, high-efficiency dispersion and transport of micron-sized metal powders while maintaining the high vacuum environment of magnetron sputtering, and to achieve uniform coating through a controllable circulation process, is a technical bottleneck that urgently needs to be overcome in the field of powder surface modification. Summary of the Invention

[0007] This invention provides a continuous coating device and method for metal powder by magnetron sputtering. It utilizes the periodic interaction of alternating electric field force and particle gravity to force metal powder particles to generate high-frequency reciprocating oscillations between the electrodes to achieve non-contact dynamic discretization. In addition, a pressure gradient barrier constructed by a differential pumping transition chamber blocks the reverse penetration of the transport gas into the high vacuum region. Thus, the "discretization-transportation-deposition-circulation" process of metal powder is coupled into a single continuous process, which solves the technical problems of uneven coating caused by van der Waals forces agglomeration of micron-sized metal powder in high vacuum environment and the incompatibility between trace transport gas and high vacuum deposition environment.

[0008] According to one aspect of the present invention, a continuous coating apparatus for magnetron sputtering of metal powder is provided, comprising: an electric field oscillation discrete section for forming an alternating high-voltage electric field in a low-pressure atmosphere, causing metal powder particles to generate reciprocating oscillating motion under the action of the electric field force, thereby continuously overcoming the van der Waals forces and electrostatic adsorption forces between particles in a non-contact manner, achieving a high degree of discreteness of the metal powder material and imparting initial kinetic energy; and a differential pumping transition chamber connected downstream of the electric field oscillation discrete section for constructing a pressure gradient that varies stepwise along the conveying direction of the metal powder material, and while allowing the discrete metal powder material to pass continuously, progressively discharging the conveying gas accompanying the metal powder material. Separation and discharge; the magnetron sputtering deposition section, connected downstream of the differential pumping transition chamber, is used to deposit a coating layer on the surface of metal powder particles by magnetron sputtering in a high vacuum environment during the continuous passage of discrete powder; the particle circulation section, connected between the magnetron sputtering deposition section and the electric field oscillation discrete section, is used to return the partially coated metal powder material to the electric field oscillation discrete section for multiple circulation processes to achieve gradual increase and control of the coating thickness; through the synergistic integration of the electric field oscillation discrete section, the differential pumping transition chamber, the magnetron sputtering deposition section, and the particle circulation section, a closed-loop processing flow of discrete-transport-deposition-circulation is formed.

[0009] Furthermore, the electric field oscillation discrete part includes a protective shell; the cavity inside the protective shell is provided with an upper electrode plate and a lower electrode plate arranged opposite to each other. The upper electrode plate and the lower electrode plate are respectively connected to the two poles of an external power source to connect an alternating high voltage current to construct a non-uniform alternating electric field between the upper electrode plate and the lower electrode plate. The combination of electric field force and the gravity of the metal powder particles constitutes a periodic action, forcing the metal powder particles to perform high-frequency reciprocating oscillation motion in the gap between the electrodes. By continuously changing the relative position and contact interface between the metal powder particles, the accumulation of van der Waals force and electrostatic adsorption force is blocked, thereby realizing the dynamic discretization of the powder bed, and the initial kinetic energy of the metal powder particles to detach from the electrodes is given by collision and electric field acceleration.

[0010] Furthermore, the protective shell is provided with an air inlet that extends into the internal space of the protective shell and passes through the lower electrode plate, so that the air inlet connects to the discrete region between the upper and lower electrode plates; the upper electrode plate is provided with a sieve hole, and the cavity between the upper and lower electrode plates is connected to the internal cavity of the differential pumping transition chamber through the sieve hole; high-purity inert gas is introduced into the discrete region through the lower electrode plate, and the flow rate of the high-purity inert gas is controlled at 10%-30% of the minimum fluidizing gas volume of the metal powder particles. The high-purity inert gas is used to provide a stable and controllable directional driving force, thereby guiding the metal powder particles that have been discrete by the electric field through the sieve hole of the upper electrode plate into the differential pumping transition chamber, so as to prevent the powder bed from entering the fluidized state.

[0011] Furthermore, the distance between the upper and lower electrode plates is 20mm-50mm; and / or the external power supply is a DC power supply with an output voltage of 5kV-20kV; and / or the sieve holes on the upper electrode plate are arranged in an array; and / or the sieve hole diameter is 50μm-200μm.

[0012] Furthermore, the differential extraction transition chamber is a hollow cylinder; multiple throttling baffles are arranged at intervals inside the differential extraction transition chamber, and each throttling baffle has a central through hole. The throttling baffles divide the differential extraction transition chamber into multiple sub-chambers that are connected sequentially along the conveying direction of the metal powder particles. The diameter of the central through hole of each throttling baffle gradually decreases along the conveying direction of the metal powder particles. The number of sub-chambers is 2 to 6. Each sub-chamber has an independent extraction port on its side wall.

[0013] Furthermore, the magnetron sputtering deposition unit includes a vacuum chamber, in which at least one magnetron sputtering target is fixedly installed; the lower end of the vacuum chamber is connected to a differential pumping transition chamber; a particle collector is also installed at the lower end of the vacuum chamber, and the vacuum chamber is connected to a particle circulation unit via the particle collector; a turbomolecular pump assembly is installed on the vacuum chamber.

[0014] Furthermore, the main body of the particle collector is in the shape of an inverted oblique cone, and the lowest point of the particle collector is connected to the particle circulation section; and / or a particle inlet is provided between the differential pumping transition chamber and the magnetron sputtering deposition section, the particle inlet passes through the particle collector and connects the differential pumping transition chamber to the vacuum chamber; and / or the magnetron sputtering target is arranged around the central axis of the particle inlet.

[0015] Furthermore, the particle circulation section includes a vacuum-locked discharge valve and a closed screw feeder; the vacuum-locked discharge valve is connected to the lowest point of the particle collector in the magnetron sputtering deposition section, the end of the vacuum-locked discharge valve away from the particle collector is connected to the closed screw feeder through a pipe, and the end of the closed screw feeder away from the vacuum-locked discharge valve is connected to the protective shell of the electric field oscillation discrete section through a pipe, and the vacuum-locked discharge valve is a double gate valve.

[0016] Furthermore, a particle concentration monitoring device is installed in the electric field oscillation discrete section, and the closed screw feeder is electrically connected to the particle concentration monitoring device.

[0017] According to another aspect of the present invention, a continuous coating method for metal powder by magnetron sputtering is also provided, employing the aforementioned continuous coating device for metal powder by magnetron sputtering, comprising the following steps: providing a low-pressure inert atmosphere environment in the electric field oscillation discrete section; applying an alternating high-voltage current between the upper and lower electrodes to construct an alternating electric field; introducing metal powder material; and utilizing the periodic action formed by the combination of electric field force and the gravity of the metal powder particles to force the metal powder particles to perform high-frequency reciprocating oscillation motion within the electrode gap; thereby continuously changing the relative positions between the metal powder particles to block the accumulation of van der Waals forces and electrostatic adsorption forces, achieving a high degree of discretization of the metal powder material and imparting initial kinetic energy for detachment from the electrodes; and introducing the discretized metal powder material into a differential pumping transition chamber, through a multi-stage throttling structure. The synergistic effect with the independent exhaust port creates a pressure gradient that varies stepwise along the conveying direction. While separating and discharging the conveying gas accompanying the metal powder material in stages, it allows the discrete metal powder material to pass through continuously, thus isolating the low-pressure discrete zone from the high-vacuum deposition zone. The discrete metal powder material passing through the differential exhaust transition chamber is conveyed to the magnetron sputtering deposition section, where a coating layer is deposited on the surface of the continuously flowing powder particles by magnetron sputtering in a high-vacuum environment. The partially coated metal powder material is returned to the electric field oscillation discrete section through the particle circulation section. The electric field oscillation discrete section is used to further discreteize the agglomerated particles, and the deposition and circulation steps are repeated until the coating layer thickness reaches the preset value, forming a closed-loop processing flow of discrete-conveyor-deposition-circulation.

[0018] The present invention has the following beneficial effects: 1. Discretization based on non-contact electric field oscillation: The electric field oscillation discrete part forces metal powder particles to generate high-frequency reciprocating oscillation motion between the plates through the periodic interaction between the alternating high voltage electric field and the gravity of the particles. By continuously doing work with the electric field force, the accumulation path of van der Waals forces and electrostatic adsorption forces between metal powder particles is blocked, realizing the dynamic discretization of the powder bed. Compared with traditional mechanical stirring or vibratory feeding, the present invention avoids the risk of introducing external mechanical impurities and does not rely on high flow rate airflow, thereby eliminating the particle breakage and dust flying phenomena common in fluidization process, ensuring that the powder entering the subsequent process is in a highly discrete single particle state.

[0019] 2. Gas-solid separation and vacuum maintenance based on differential pumping transition chamber: The differential pumping transition chamber constructs a stepped pressure gradient along the conveying direction through a multi-stage throttling structure. Utilizing the physical properties of the mean free path of gas molecules and the pressure gradient, it allows discrete metal powder particles to pass continuously while progressively impeding and removing the trace amounts of conveyed gas accompanying the metal powder. This effectively decouples the low-pressure environment required for powder conveying from the high-vacuum environment required for magnetron sputtering. Without interrupting the metal powder flow, the conveyed gas is blocked outside the deposition zone, ensuring that the magnetron sputtering deposition section can maintain a stable vacuum of 10°C for a long period. -2 Pa to 10 -3 The high vacuum level of Pa significantly improves the purity and density of the deposited film.

[0020] 3. Uniform coating based on high-vacuum magnetron sputtering: Due to the effective isolation of the differential pumping transition chamber, the magnetron sputtering deposition section can operate in a high vacuum without interference from the transport gas; when the discrete single-particle powder passes through the deposition zone, its entire surface is exposed to the high-energy sputtering particle stream, and because the particles are in motion, the probability of each surface receiving deposition is equal, thereby achieving three-dimensional uniform coating of the entire surface of micron-sized powder, avoiding the shadow effect and coating dead corners caused by particle agglomeration.

[0021] 4. Precise control of coating thickness based on particle circulation section: The particle circulation section establishes a physical pathway from the deposition end back to the discrete beginning, forming a closed-loop processing flow. This allows the metal powder to be circulated multiple times within the device, transforming the thin-layer growth of a single deposition into a gradual thickening through multiple cycles. This not only solves the problem of insufficient coating thickness in a single pass, but also enables precise control of the final coating thickness by adjusting the number of cycles or the cycle speed, meeting the differentiated requirements of film thickness for different application scenarios.

[0022] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of a metal powder magnetron sputtering continuous coating device according to a preferred embodiment of the present invention; Figure 2 This is a three-dimensional structural schematic diagram of a metal powder magnetron sputtering continuous coating device according to a preferred embodiment of the present invention; Figure 3 This is an SEM image of the coated metal powder particles according to a preferred embodiment of the present invention.

[0024] Legend: 1. Electric field oscillation discrete section; 11. Lower electrode plate; 12. Upper electrode plate; 13. Protective shell; 14. Air inlet; 2. Differential extraction transition chamber; 21. Throttling baffle; 22. Independent extraction port; 3. Magnetron sputtering deposition section; 31. Magnetron sputtering target; 32. Vacuum chamber; 33. Particle inlet; 34. Particle collector; 4. Particle circulation section; 41. Vacuum-locked discharge valve; 42. Sealed screw feeder. Detailed Implementation

[0025] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0026] like Figure 1 and Figure 2As shown, the continuous coating device for metal powder magnetron sputtering in this embodiment includes: an electric field oscillation discrete section 1, used to form an alternating high-voltage electric field in a low-pressure atmosphere, causing metal powder particles to generate reciprocating oscillating motion under the action of the electric field force, continuously overcoming the van der Waals force and electrostatic adsorption force between particles in a non-contact manner, realizing the high discreteness of the metal powder material and imparting initial kinetic energy; a differential pumping transition chamber 2, connected downstream of the electric field oscillation discrete section 1, used to construct a pressure gradient that varies stepwise along the conveying direction of the metal powder material, and while allowing the discrete metal powder material to pass through continuously, to perform stepwise separation and discharge of the conveying gas accompanying the metal powder material; a magnetic... The magnetron sputtering deposition unit 3, connected downstream of the differential pumping transition chamber 2, is used to deposit a coating layer on the surface of metal powder particles via magnetron sputtering in a high-vacuum environment during the continuous passage of discrete powder. The particle circulation unit 4, connected between the magnetron sputtering deposition unit 3 and the electric field oscillation discrete unit 1, is used to return the partially coated metal powder material to the electric field oscillation discrete unit 1 for multiple cycles, thereby achieving gradual increase and control of the coating thickness. Through the synergistic integration of the electric field oscillation discrete unit 1, the differential pumping transition chamber 2, the magnetron sputtering deposition unit 3, and the particle circulation unit 4, a closed-loop processing flow of discrete-transport-deposition-circulation is formed. Optionally, the high-vacuum environment is 10... -2 Pa-10 -3 Pa. The present invention relates to a continuous coating device for magnetron sputtering of metal powder. The electric field oscillation discrete section 1, through the periodic interaction between an alternating high-voltage electric field and particle gravity, forces the metal powder particles to generate high-frequency reciprocating oscillations between the electrodes. By continuously performing work using the electric field force, the accumulation path of van der Waals forces and electrostatic adsorption forces between the metal powder particles is blocked, achieving dynamic discreteness of the powder bed. Compared to traditional mechanical stirring or vibratory feeding, the present invention avoids the risk of introducing external mechanical impurities and does not rely on high-flow airflow, thereby eliminating the particle breakage and dust dispersion phenomena commonly seen during fluidization, ensuring that the powder entering subsequent processes is in a highly discrete single-particle state. The differential extraction transition chamber 2 constructs a stepped pressure gradient along the conveying direction through a multi-stage throttling structure. Utilizing the physical properties of the mean free path of gas molecules and the pressure gradient, it allows discrete metal powder particles to pass continuously while progressively impeding and extracting the trace amounts of conveying gas accompanying the metal powder. This effectively decouples the low-pressure environment required for powder conveying from the high-vacuum environment required for magnetron sputtering. Without interrupting the metal powder flow, the conveying gas is blocked outside the deposition zone, ensuring that the magnetron sputtering deposition section 3 can maintain a stable pressure of 10 kJ / m³ for a long period. -2 Pa to 10 -3The high vacuum level of Pa significantly improves the purity and density of the deposited film. Due to the effective isolation of the differential pumping transition chamber 2, the magnetron sputtering deposition unit 3 operates in a high vacuum unaffected by the transport gas. When the discrete single-particle powder passes through the deposition zone, its entire surface is exposed to the high-energy sputtering particle stream. Because the particles are in motion, each surface has an equal probability of receiving deposition, thus achieving uniform three-dimensional coating of the micron-sized powder, avoiding shadowing effects and coating dead zones caused by particle agglomeration. The particle circulation unit 4 establishes a physical pathway from the deposition end back to the discrete beginning, forming a closed-loop processing flow. This allows the metal powder to undergo multiple cycles within the device, transforming the thin-layer growth of a single deposition into a gradual thickening through multiple cycles. This not only solves the problem of insufficient coating thickness in a single pass but also allows for precise control of the final coating thickness by adjusting the number of cycles or the circulation speed, meeting the differentiated requirements of different application scenarios for film thickness. The electric field oscillation discrete section 1, the differential pumping transition chamber 2, the magnetron sputtering deposition section 3, and the particle circulation section 4 are tightly coupled through a "discretion-transportation-deposition-circulation" logic. The initial kinetic energy imparted by the electric field oscillation reduces the dependence on gas for subsequent transport, the differential pumping ensures the purity of the deposition environment, and the circulation loop improves the integrity of the coating. This synergistic effect enables the entire device to complete continuous processing from raw material input to finished product output within a single system, significantly improving process integration and production efficiency. This invention's continuous magnetron sputtering coating device for metal powder solves the technical problems of easy agglomeration, difficult transport, and easy leakage of micron-sized metal powders under high vacuum conditions by combining an electric field-driven non-contact discrete mechanism with a differential pumping pressure gradient isolation mechanism. Furthermore, the closed-loop circulation achieves precise control of coating quality, providing a continuous, stable, efficient, and high-purity industrial solution for the surface modification of metal powders.

[0027] like Figure 1 and Figure 2As shown, in this embodiment, the electric field oscillation discrete part 1 includes a protective shell 13; the inner cavity of the protective shell 13 is provided with an upper electrode plate 12 and a lower electrode plate 11 arranged opposite to each other. The upper electrode plate 12 and the lower electrode plate 11 are respectively connected to the two poles of an external power source to connect an alternating high voltage current to construct a non-uniform alternating electric field between the upper electrode plate 12 and the lower electrode plate 11. The combination of electric field force and the gravity of the metal powder particles constitutes a periodic action, forcing the metal powder particles to perform high-frequency reciprocating oscillation motion in the gap between the electrodes. By continuously changing the relative position and contact interface between the metal powder particles, the accumulation of van der Waals force and electrostatic adsorption force is blocked, thereby realizing the dynamic discretization of the powder bed, and the initial kinetic energy of the metal powder particles to detach from the electrodes is given by collision and electric field acceleration. The upper electrode 12 and the lower electrode 11 are connected to an alternating high voltage current, creating a non-uniform alternating electric field in the cavity inside the protective shell 13. When this electric field acts on the metal powder particles, the particles are polarized by the electric field and generate an induced dipole moment. Under the action of the electric field gradient, they are subjected to dielectric force. Due to the periodic reversal of the electric field polarity, the direction of the electric force on the particles changes alternately, forming a periodic game with the particle's own gravity. This forces the particles to generate high-frequency reciprocating oscillation motion in the gap between the electrodes. This motion continuously changes the relative position and contact interface between the particles, blocking the accumulation path of van der Waals forces and electrostatic adsorption forces, destroying the particle agglomeration structure, realizing the dynamic discretization of the powder bed, and without the intervention of mechanical parts throughout the process, avoiding the introduction of external impurities. The high-frequency reciprocating oscillation of particles within the gap between the electrodes causes continuous relative sliding and collisions between particles. The shear and impact forces generated in this process are far greater than the adhesion work between particles, effectively breaking up existing soft agglomerates and restoring the particles to a monodisperse state. The oscillating motion keeps the particle surface continuously exposed to the electric field, preventing electrostatic adsorption caused by local charge accumulation and maintaining the discrete stability of the particles. During the oscillation process, particles collide with the electrodes or other particles, gaining rebound kinetic energy. The alternating electric field applies an accelerating force to the particles at the moment of polarity reversal, converting electrical energy into mechanical energy. This dual effect gives the particles the initial kinetic energy to detach from the electrodes, enabling them to overcome resistance in the subsequent conveying process (such as gas resistance, gravitational components, etc.), ensuring that the particles can smoothly enter the differential pumping transition chamber 2 and maintain the stability of continuous conveying. The initial kinetic energy imparted by the electric field oscillation discrete section 1 reduces the dependence on subsequent gas delivery, allowing for the use of trace gas-assisted delivery. This reduces the gas flow rate entering the differential pumping transition chamber 2, lessening its pumping load and improving vacuum maintenance efficiency. Dynamic discretization ensures that the particles entering the magnetron sputtering deposition section 3 are in a single-particle state, avoiding uneven coating caused by agglomerates and improving the quality consistency of the deposited layer. The electric field oscillation discrete section 1 uses a non-uniform alternating electric field constructed by alternating high-voltage current, which works in conjunction with particle gravity to achieve high-frequency reciprocating oscillation of metal powder particles in a non-contact manner. This blocks the accumulation of adhesion forces between particles, completes dynamic discretization, and imparts initial kinetic energy, providing a discrete particle basis for subsequent differential pumping, high-vacuum deposition, and cyclic processing.

[0028] like Figure 1 and Figure 2As shown, in this embodiment, the protective shell 13 is provided with an air inlet 14, which extends into the internal space of the protective shell 13 and passes through the lower electrode plate 11, so that the air inlet 14 is connected to the discrete region between the upper electrode plate 12 and the lower electrode plate 11; the upper electrode plate 12 is provided with a sieve hole, and the cavity between the upper electrode plate 12 and the lower electrode plate 11 is connected to the internal cavity of the differential pumping transition chamber 2 through the sieve hole; high-purity inert gas is introduced into the discrete region through the lower electrode plate 11, and the flow rate of the high-purity inert gas is controlled at 10%-30% of the minimum fluidizing gas volume of the metal powder particles. The high-purity inert gas is used to provide a stable and controllable directional driving force, thereby guiding the metal powder particles that have been discrete by the electric field through the sieve hole of the upper electrode plate 12 into the differential pumping transition chamber 2, so as to prevent the powder bed from entering the fluidized state. The inlet 14 passes through the lower electrode plate 11 to introduce high-purity inert gas into the discrete zone, and the gas flow rate is strictly controlled to be 10%-30% of the minimum fluidizing gas volume of the metal powder particles. This flow rate range ensures that the gas velocity is insufficient to overcome the adhesion force and gravity between particles to form a fluidized bed. Instead, a weak directional airflow is formed with an extremely low apparent gas velocity. Based on the initial kinetic energy given to the particles by the electric field oscillation discrete section 1, this airflow provides a stable additional driving force, guiding the discrete single particles or small components to overcome gravity and airflow resistance, and to be transported upward and pass through the sieve holes of the upper electrode plate 12. This achieves a smooth transition from "electric field discreteness" to "pneumatic guidance" and ensures the continuity of the powder flow. Because the gas flow rate is strictly limited to below the minimum fluidizing gas volume, the powder bed remains in a fixed or creeping state, rather than a boiling fluidized state. This avoids the violent particle collisions, breakage, and electrostatic accumulation caused by high-velocity fluidization, maintaining the integrity of individual particles after the electric field is discrete. The weak airflow does not generate a positive pressure gradient sufficient to compact the powder. Combined with the oscillating motion of the particles themselves, this effectively prevents bridging and clogging of the powder at the sieve openings, ensuring the long-term permeability and transport stability of the sieve openings. High-purity inert gas (such as argon) is used as the transport medium, creating an inert atmosphere in the discrete zone and transport path. This effectively isolates reactive gases such as oxygen and water vapor, preventing surface pre-oxidation or hydrolysis of highly reactive metal powders (such as aluminum, magnesium, and titanium) during transport and deposition. This ensures the chemical purity of the surface to be coated, providing a highly reactive substrate surface for subsequent magnetron sputtering deposition, which is beneficial for improving the bonding strength between the coating layer and the substrate. The air inlet 14 is located on the lower electrode plate 11, and the airflow direction is from bottom to top, which is consistent with the particle movement direction generated by the electric field oscillation, forming a superposition of gas-solid two-phase flow in the same direction. The weak airflow not only provides driving force, but also plays a "sweeping" role, assisting the discrete particles to detach from the electrode plate surface, reducing the residence time of particles on the electrode plate, and further improving the dispersion efficiency. The introduction of inert gas does not affect the distribution characteristics of the electric field. The two do not interfere with each other in space, but act synchronously in time, jointly ensuring the dispersion and transportation of powder.The gas-powder mixture entering the differential pumping transition chamber 2 through the sieve holes has an extremely low gas flow rate, significantly reducing the requirements on the pumping capacity of the differential pumping transition chamber 2. This allows the differential pumping transition chamber 2 to achieve gas separation at a lower pumping speed, maintaining the pressure difference between the upstream and downstream sides and preventing the deterioration of the vacuum level in the magnetron sputtering deposition section 3 due to a large influx of gas, thus ensuring the stability of the high-vacuum deposition environment. The combination of the gas inlet and the sieve hole structure, through strict control of the delivery of a small amount of inert gas in a sub-fluidized state, achieves directional guidance and anti-clogging protection for the discrete metal powder. While avoiding disruption of the electric field discrete effect, it completes the efficient transfer of powder from the discrete region to the differential pumping transition chamber 2, while providing an inert protective environment. It is the hub connecting discrete and vacuum transport in the entire device, ensuring the continuity and process stability of the entire process.

[0029] like Figure 1 and Figure 2As shown, in this embodiment, the distance between the upper electrode plate 12 and the lower electrode plate 11 is 20mm-50mm; and / or the external power supply is a DC power supply with an output voltage of 5kV-20kV; and / or the sieve holes on the upper electrode plate 12 are arranged in an array; and / or the aperture of the sieve holes is 50μm-200μm. The distance between the upper electrode plate 12 and the lower electrode plate 11 is set to 20mm-50mm, which matches the particle size of the micron-sized metal powder and the required electric field strength. Under the application of a DC high voltage of 5kV-20kV, this distance can form a strong electric field with a suitable field strength and relatively uniform distribution between the electrodes, ensuring that the electric field force is sufficient to overcome the particle gravity and adhesion force to drive oscillation, while avoiding powder accumulation and blockage or discharge breakdown due to too small a distance, and also preventing insufficient dispersion due to field strength attenuation caused by too large a distance. This size design provides sufficient oscillation space for the metal powder, ensuring that the particles can carry out a complete high-frequency reciprocating motion trajectory. The external power supply uses a DC high-voltage power supply with an output voltage of 5kV-20kV. During the movement of the metal powder particles, the surface charge is not fixed but changes dynamically with the contact plates. When the particles contact the lower plate, they acquire the same polarity of charge as the lower plate and are thus subjected to an upward electric field repulsion, moving towards the upper plate. When the particles reach the surface of the upper plate, their original charge is neutralized, and they acquire the same polarity of charge as the upper plate again, thus being attracted downward by the lower plate. This cycle continues, and the particles achieve stable vertical reciprocating oscillation under the action of the DC electric field. This voltage range can provide sufficient electric field force to drive the metal powder to overcome van der Waals forces and electrostatic adsorption forces, while maintaining it within the safe discharge threshold under vacuum or low-pressure atmosphere, effectively avoiding damage to the powder and equipment from continuous electric arcs, and achieving controllable adjustment of discrete intensity. The sieve holes on the upper electrode plate 12 are arranged in an array. This geometric configuration ensures that the flow area between the discrete zone and the differential pumping transition chamber 2 is uniformly distributed. The array arrangement of the sieve holes eliminates local flow dead zones, allowing the discrete powder to rise uniformly along multiple channels perpendicular to the electrode plate under the drive of a weak airflow. This avoids local powder accumulation or channeling caused by uneven flow, thus ensuring that the powder flow entering the subsequent deposition zone has uniform spatiotemporal distribution characteristics. The pore size is set to 50μm-200μm, which is designed to provide dual screening for micron-sized metal powders. The pore size is significantly larger than the particle size of the target metal powder (usually several microns to tens of microns), ensuring that individual particles can pass through smoothly and are less prone to physical blockage. This pore size, combined with the weak airflow in the subfluidized state, can physically trap small agglomerates or ultra-large particles that have not been completely dispersed by the electric field, preventing unqualified particles from entering the magnetron sputtering deposition section 3 and affecting the coating quality. This pore size range maintains the structural strength of the upper electrode plate 12 as an electrode while ensuring the flow capacity.The aforementioned parameters—plate spacing, power supply voltage, sieve arrangement, and aperture size—are not isolated but rather work synergistically to lock in the optimal process window. The plate spacing determines the electric field distribution, and the power supply voltage determines the magnitude of the electric field force; together, they determine the oscillation amplitude and frequency. The sieve aperture size and arrangement determine the resistance and uniformity of powder passage, and together with the air inlet flow rate, they determine the conveying stability. This organic combination of parameters enables the electric field oscillation discrete unit 1 to operate stably in the optimal discrete state for a long period under low energy and low gas consumption conditions. By limiting the plate spacing, DC high voltage parameters, sieve arrangement, and aperture size, the electric field distribution, particle trajectory, and gas-solid two-phase flow morphology are precisely controlled from both geometric constraints and physical field strength dimensions. This achieves efficient discreteness, uniform conveying, and particle size screening of metal powder in a sub-fluidized state, providing a stable and controllable discrete powder source for the entire continuous coating device.

[0030] like Figure 1 and Figure 2 As shown, in this embodiment, the differential extraction transition chamber 2 is a hollow cylinder; multiple throttling baffles 21 are arranged at intervals inside the differential extraction transition chamber 2, and each throttling baffle 21 has a central through hole. The throttling baffles 21 divide the differential extraction transition chamber 2 into multiple sub-chambers that are sequentially connected along the conveying direction of the metal powder particles. The diameter of the central through hole of each throttling baffle 21 gradually decreases along the conveying direction of the metal powder particles. The number of sub-chambers is 2 to 6. Each sub-chamber has an independent extraction port 22 on its side wall. The differential pumping transition chamber 2 is equipped with multiple throttling baffles 21, which divide the internal cavity into multiple sub-chambers connected sequentially along the conveying direction. The diameter of the central through hole on each throttling baffle 21 decreases step by step along the conveying direction of the metal powder particles. By utilizing the throttling effect in fluid mechanics, a significant flow conduction restriction is constructed between adjacent sub-chambers. When gas molecules diffuse from upstream (to the side of the electric field oscillation discrete section 1) to downstream (to the side of the magnetron sputtering deposition section), the flow cross-sectional area decreases sharply after each throttling baffle 21, which causes the mean free path and collision frequency of the gas molecules to change, thereby forming a stepped decreasing pressure distribution in each sub-chamber. The establishment of this pressure gradient effectively blocks the direct gas communication between the downstream high vacuum region and the upstream low pressure region. Each sub-chamber has an independent evacuation port 22 on its side wall. This configuration allows for independent adjustment of the evacuation rate according to the pressure requirements of each sub-chamber. Differential evacuation through the independent evacuation ports 22 allows residual gas leaking through the throttling baffle 21 or carried in by the powder to be extracted at each stage. This achieves step-by-step stripping and removal of gas molecules, ensuring that the gas transported with the metal powder particles is significantly removed before reaching the magnetron sputtering deposition section 3. This effectively prevents a very small amount of gas from entering the high-vacuum deposition area, ensuring that the magnetron sputtering deposition section 3 can maintain a 10... -2 Pa to 10 -3The high vacuum environment of Pa. The diameter of the central through-hole of the throttling baffle 21 gradually decreases along the conveying direction of the metal powder particles. This design fully considers the movement trajectory of the metal powder particles while constructing gas flow resistance. Due to the large mass and inertia of the metal powder particles, they can move in a straight or near-straight line along the axial direction and pass through the central through-holes of each stage under the drive of weak airflow or their own kinetic energy. The gradual shrinkage design of the aperture not only does not constitute a substantial obstacle to the passage of macroscopic particles, but also helps to constrain the diameter of the powder stream, prevent the powder from dispersing and adhering to the inner wall of the chamber, and improve the powder collection efficiency. The number of sub-chambers is set to 2-6. This number range achieves the best balance between vacuum maintenance effect and structural complexity. If there are fewer than two sub-chambers, an effective pressure step cannot be formed, making it difficult to block the gas. If there are more than six, the structure will be too long, the flow resistance will be too large, and it will hinder the passage of powder. The range of 2-6 sub-chambers can provide sufficient pressure drop, while ensuring that the kinetic energy loss of the powder when passing through the multi-stage throttling structure is within an acceptable range, ensuring that the powder can smoothly enter the magnetron sputtering deposition section 3. The hollow cylindrical transition chamber structure provides axisymmetric airflow and particle flow channels, forming a good flow field connection with the sieve array arrangement of the upper electrode plate 12. Upstream, it receives discrete powder and trace gases output from the electric field oscillation discrete section 1, while downstream, it connects to the vacuum chamber 32 in the high-vacuum environment of the magnetron sputtering deposition section 3. Through internal throttling and pumping coordination, the differential pumping transition chamber 2 successfully decouples the low-pressure environment required for powder transport from the high-vacuum environment required for magnetron sputtering, allowing the upstream and downstream processes to operate independently within their respective optimal pressure ranges without interference. The differential pumping transition chamber 2 constructs a stepped pressure gradient through multi-stage throttling baffles 21 and utilizes independent pumping ports 22 to achieve step-by-step gas separation and removal. While allowing continuous passage of metal powder particles, it effectively blocks the reverse permeation of transport gas into the high-vacuum region, resolving the physical contradiction between trace transport and high-vacuum maintenance, and ensuring a continuous and stable pressure matching interface for the entire device under high-vacuum conditions.

[0031] like Figure 1 and Figure 2 As shown, in this embodiment, the magnetron sputtering deposition unit 3 includes a vacuum chamber 32, within which at least one magnetron sputtering target 31 is fixedly installed; the lower end of the vacuum chamber 32 is connected to the differential pumping transition chamber 2; a particle collector 34 is also installed at the lower end of the vacuum chamber 32, and the vacuum chamber 32 is connected to the particle circulation unit 4 via the particle collector 34; a turbomolecular pump assembly is installed on the vacuum chamber 32. The vacuum chamber 32, equipped with the turbomolecular pump assembly, can stably maintain the internal pressure of the chamber at 10... -2 Pa to 10 -3The high vacuum level of Pa effectively reduces the partial pressure of residual gas molecules (such as oxygen, nitrogen, and water vapor), greatly reducing the probability of collisions between sputtered particles and gas molecules during flight and shortening the mean free path of the particles. This ensures that sputtered particles reach the surface of metal powder particles with high kinetic energy and pure chemical composition, avoiding oxide inclusions or porosity defects in the coating layer and significantly improving the density and chemical purity of the film. At least one magnetron sputtering target 31 is fixedly installed inside the vacuum chamber 32. This design supports the deposition of a single target material for a single-element coating layer, as well as the co-sputtering or alternating sputtering of multiple targets of different materials. By adjusting the sputtering power, duty cycle, or pulse frequency of each target material, the chemical composition and microstructure of the coating layer (such as gradient layers, multilayer films, or composite films) can be precisely controlled at the atomic scale, realizing the customized design of the coating layer function. The multi-target layout increases the sputtering particle flux and improves the deposition efficiency per unit time. Discretized metal powder particles continuously pass through the internal region of the vacuum chamber 32 under the drive of a weak airflow or their own kinetic energy. Because the particles are in a dynamic flight or tumbling state, and the plasma region generated by the magnetron sputtering target 31 has three-dimensional spatial distribution characteristics, each surface of the metal powder particles can be uniformly exposed to the sputtered particle stream. This dynamic deposition mode eliminates the shadowing effect present in planar deposition, ensuring that micron-sized powder particles obtain a uniformly thick coating layer in three-dimensional space, achieving true full-surface coating. The particle collector 34 installed at the lower end of the vacuum chamber 32 not only serves as a temporary storage container for the deposited powder but also plays a role in gas-solid separation and buffering. The particle collector 34 receives the deposited powder, preventing it from directly impacting downstream pipelines and causing blockages or wear. It also collects the powder and orderly guides it into the particle circulation section 4, ensuring a smooth transition of powder from the deposition area to the circulation system under high vacuum conditions, maintaining the continuity of the process flow. The lower end of the vacuum chamber 32 is connected to the differential pumping transition chamber 2, directly receiving the discrete powder and trace residual gas after differential pumping. Since the differential pumping transition chamber 2 has discharged most of the transport gas, the turbomolecular pump group in the vacuum chamber 32 only needs to handle a very small amount of leaked gas and trace impurity gas generated during sputtering, greatly reducing the pumping load and ensuring the long-term stability of the high vacuum environment. The connection between the particle collector 34 and the particle circulation section 4 forms a closed-loop outlet of "deposition-collection-circulation", making this section not only the site of coating but also the hub connecting the front and back-end processes. The magnetron sputtering deposition section 3 achieves high-purity, all-round, and uniform coating of discrete metal powder particles through the high vacuum environment created by the turbomolecular pump group, the controllable deposition source provided by the magnetron sputtering target 31, and the dynamic deposition mode. The seamless connection between the magnetron sputtering deposition section, the differential pumping transition chamber, and the particle circulation section 4 ensures the continuity and stability of the coating process under high vacuum conditions, thereby achieving high-quality surface modification.

[0032] like Figure 1 and Figure 2 As shown, in this embodiment, the main body of the particle collector 34 is an inverted oblique cone shape, and the lowest point of the particle collector 34 is connected to the particle circulation section 4; and / or a particle inlet 33 is provided between the differential pumping transition chamber 2 and the magnetron sputtering deposition section 3, the particle inlet 33 passes through the particle collector 34 and connects the differential pumping transition chamber 2 to the vacuum chamber 32; and / or the magnetron sputtering target 31 is arranged around the central axis of the particle inlet 33. The main body of the particle collector 34 is an inverted oblique cone shape. This geometric configuration utilizes the component of gravity and the guiding effect of the wall to allow the metal powder particles that have completed magnetron sputtering deposition to naturally converge towards the lowest point during the falling process; the oblique cone wall avoids the flow dead zone at the right angle turn, prevents powder from accumulating or bridging in the corner, and ensures that the discrete powder can smoothly and completely slide to the lowest point and enter the particle circulation section 4, eliminating the risk of powder accumulation at the bottom of the vacuum chamber 32 and maintaining the continuity of the process flow. The particle inlet 33, located between the differential pumping transition chamber 2 and the magnetron sputtering deposition section 3, passes through the particle collector 34 and directly introduces the discrete powder into the vacuum chamber 32, establishing a direct channel from the low-pressure discrete zone to the high-vacuum deposition zone. This avoids the powder from meandering or lingering in the collector and reduces ineffective collisions between particles and the wall. The direct-flow design maximizes the retention of the initial kinetic energy gained by the powder from upstream, ensuring that the powder stream maintains a concentrated spatiotemporal distribution when entering the deposition zone, which is beneficial for maintaining a stable deposition flux. The magnetron sputtering targets 31 are arranged around the central axis of the particle inlet 33. This spatial configuration allows the plasma regions generated by multiple targets to surround the powder stream. When metal powder particles pass along the central axis, their surfaces are exposed to the sputtered particle streams of each target sequentially or simultaneously during flight. This 360-degree surrounding deposition mode, combined with the tumbling or rotation of the particles themselves, ensures that each surface of the powder particles receives a uniform particle flux, completely eliminating single-sided deposition or shadowing effects and achieving true full-surface uniform coating. An inverted, cone-shaped particle collector 34 is located below the particle inlet 33, forming a vertically stacked layout of "inlet-deposition zone-collection zone" in space. Metal powder enters from the upper particle inlet 33, completes deposition in the middle region, then falls into the lower collector and finally exits from the lowest point. This compact layout optimizes the synergistic effect of the flow field and gravity field within the cavity, achieving efficient powder transport, deposition, and collection within a limited space, thus improving the equipment's space utilization and process efficiency. The inverted cone-shaped collector enables unobstructed powder convergence and discharge, the through-type particle inlet 33 ensures stable powder flow, and the surrounding target arrangement achieves omnidirectional uniform deposition. These three elements work synergistically to construct an efficient, uniform, and continuous powder processing channel within the magnetron sputtering deposition section 3, improving the quality consistency and process stability of the coating layer.

[0033] like Figure 1 and Figure 2 As shown, in this embodiment, the particle circulation section 4 includes a vacuum-locked discharge valve 41 and a closed screw feeder 42; the vacuum-locked discharge valve 41 is connected to the lowest point of the particle collector 34 of the magnetron sputtering deposition section 3, the end of the vacuum-locked discharge valve 41 away from the particle collector 34 is connected to the closed screw feeder 42 through a pipe, and the end of the closed screw feeder 42 away from the vacuum-locked discharge valve 41 is connected to the protective shell 13 of the electric field oscillation discrete section 1 through a pipe, and the vacuum-locked discharge valve 41 is a double gate valve. The vacuum-locked discharge valve 41 adopts a double-gate valve structure and is connected in series between the particle collector 34 and the closed screw feeder 42. The double-gate valve structure has the functions of independent opening and closing and vacuuming of the intermediate chamber. During operation, by alternately opening and closing the upstream and downstream gates, it can discharge the deposited powder while cutting off the direct connection between the high vacuum chamber 32 of the magnetron sputtering deposition section 3 and the external environment or downstream atmospheric pressure equipment. This dual-stage isolation mechanism effectively prevents atmospheric backflow or gas leakage, maintaining the internal 10 of the magnetron sputtering deposition section 3. -2 Pa to 10 -3The high vacuum environment stability of Pa avoids vacuum fluctuations caused by frequent discharge. The closed screw feeder 42 is connected to the vacuum-locked discharge valve 41 and the protective shell 13 of the electric field oscillation discrete section 1 through a pipeline, forming a fully enclosed material circulation channel. The closed screw feeder 42 uses the rotation of the screw blades to push the powder forward. During the conveying process, it can not only accurately control the powder flow rate returning to the electric field oscillation discrete section 1 and realize the gradual adjustment of the coating thickness, but also form an effective powder sealing section through its own screw structure, further blocking gas backflow. This airtight conveying ensures that the powder returning to the discrete section does not carry a large amount of air, reducing the pumping load of the differential pumping transition chamber 2. The particle circulation section 4 establishes a physical pathway from the end of the magnetron sputtering deposition section 3 back to the beginning of the electric field oscillation and dispersion section 1, forming a closed-loop processing flow. This allows the metal powder to undergo multiple circulation processes within the device, with each circulation completing a thin-layer deposition. Through the cumulative effect, the coating thickness gradually increases. This progressive thickening mechanism solves the problem of insufficient coating thickness in a single pass. Furthermore, by adjusting the number of cycles or the rotation speed of the screw feeder, precise control of the final coating thickness can be achieved, meeting the differentiated requirements of film thickness for different application scenarios. The vacuum-locked discharge valve 41 is directly connected to the lowest point of the particle collector 34, receiving the deposited powder and ensuring continuous powder flow. The closed screw feeder 42 re-feeds the powder back to the electric field oscillation and dispersion section 1. At this point, the powder may have slightly agglomerated, and the electric field oscillation and dispersion section 1 has the function of re-dispersion, forming a complementary function. This synergistic effect ensures that the recycled powder can be re-dispersed before entering the next deposition, guaranteeing that it is in a discrete state each time it passes through the deposition zone, thereby maintaining the stability of the coating quality. The particle circulation unit 4 ensures the stability of the high vacuum environment through the dual-gate valve dual-stage vacuum locking mechanism. The closed screw feeder 42 realizes the quantitative and airtight return of powder. By constructing a closed-loop circulation circuit, it realizes the progressive and precise control of the coating thickness and the multiple utilization of metal powder. It is a feedback and adjustment unit for realizing continuous, controllable and efficient coating.

[0034] In this embodiment, a particle concentration monitoring device is installed inside the electric field oscillation discrete section 1, and the closed screw feeder 42 is electrically connected to the particle concentration monitoring device. The particle concentration monitoring device installed inside the electric field oscillation discrete section 1 can acquire the volume concentration or mass concentration data of metal powder particles in the discrete zone in real time; the particle concentration monitoring device and the closed screw feeder 42 establish an electrical signal connection to form a closed-loop control system; when the monitored particle concentration deviates from the preset process window, the control system automatically adjusts the motor speed of the closed screw feeder 42, thereby changing the powder flow rate returning to the electric field oscillation discrete section 1; this adaptive adjustment mechanism ensures that a constant particle load is always maintained in the discrete zone, avoiding incomplete dispersion due to excessive feeding or low deposition efficiency due to insufficient feeding, and realizing steady-state operation of the process. The dispersion efficiency of the electric field oscillation dispersion section 1 is closely related to the particle concentration. Excessive concentration leads to frequent collisions between particles, increasing van der Waals forces and hindering single-particle dispersion. Insufficient concentration reduces processing efficiency. Through the linkage between the particle concentration monitoring device and the closed-loop screw feeder 42, the particle concentration in the dispersion zone can be precisely controlled within the optimal range, maximizing the effect of the alternating high-voltage electric field and ensuring that each particle receives sufficient electric force to overcome adhesion, thereby improving the overall dispersion quality and uniformity. When the dispersion capability of the electric field oscillation dispersion section 1 decreases due to unexpected conditions (such as electrode fouling or voltage fluctuations), resulting in an abnormally high particle concentration, the particle concentration monitoring device can quickly capture the signal and feed it back to the closed-loop screw feeder 42, triggering a deceleration or pause command. This preventative mechanism effectively prevents excessive powder from entering the deposition zone, avoiding uneven coating or equipment blockage caused by powder agglomeration, protecting the magnetron sputtering target 31 and the vacuum chamber 32 from contamination, and significantly improving the system's operational stability and safety. The particle circulation section 4 aims to achieve a gradual increase in coating thickness, and particle concentration monitoring and feedback control are prerequisites for achieving this goal. By precisely controlling the feed rate for each cycle, it can be ensured that each batch of powder entering the deposition zone receives uniform and sufficient coating. This collaborative "monitoring-adjustment-circulation" mode makes the increase in coating thickness predictable and repeatable, providing reliable data support for quality control in industrial production. The particle concentration monitoring device is electrically connected to the closed screw feeder 42, constructing a closed-loop feedback control system in the particle circulation process. This enables real-time monitoring of particle concentration in the discrete zone and adaptive adjustment of the feed rate, ensuring that the electric field oscillation discrete section 1 always operates under optimal conditions, thereby guaranteeing the stability, safety, and uniformity of coating quality of the entire device.

[0035] The continuous coating method for metal powder by magnetron sputtering in this embodiment uses the aforementioned continuous coating device for metal powder magnetron sputtering, and includes the following steps: In the electric field oscillation discrete section 1, a low-pressure inert atmosphere is provided; an alternating high-voltage current is applied between the upper electrode 12 and the lower electrode 11 to construct an alternating electric field; after the metal powder material is introduced, the periodic action formed by the combination of the electric field force and the gravity of the metal powder particles forces the metal powder particles to perform high-frequency reciprocating oscillation motion within the electrode gap; by continuously changing the relative position between the metal powder particles to block the accumulation of van der Waals forces and electrostatic adsorption forces, the metal powder material is highly discreteized and given initial kinetic energy to detach from the electrode; the discrete metal powder material is then introduced into the differential extraction transition chamber 2, and through a multi-stage throttling structure and an independent extraction port 2... The synergistic effect of 2 constructs a pressure gradient that varies stepwise along the conveying direction. While separating and discharging the conveying gas accompanying the metal powder material in stages, it allows the discrete metal powder material to pass through continuously, thus isolating the low-pressure discrete zone from the high-vacuum deposition zone. The discrete metal powder material passing through the differential pumping transition chamber 2 is conveyed to the magnetron sputtering deposition section 3, where a coating layer is deposited on the surface of the continuously flowing powder particles by magnetron sputtering in a high-vacuum environment. The metal powder material that has been partially coated by the magnetron sputtering deposition section 3 is returned to the electric field oscillation discrete section 1 through the particle circulation section 4. The electric field oscillation discrete section 1 is used to further discreteize the agglomerated particles, and the deposition and circulation steps are repeated until the coating layer thickness reaches the preset value, forming a closed-loop processing flow of discrete-conveyor-deposition-circulation. The present invention provides a continuous coating method for metal powder by magnetron sputtering. In the electric field oscillation discrete section 1, an alternating electric field is constructed by applying an alternating high-voltage current. By utilizing the periodic interplay between the electric field force and the particle gravity, the metal powder particles are forced to generate high-frequency reciprocating oscillation motion within the gap between the electrodes. This process blocks the accumulation path of van der Waals forces and electrostatic adsorption forces between particles, avoiding impurities and temperature rise introduced by traditional mechanical stirring or vibratory feeding, and achieving a high degree of discretization of the metal powder material under a low-pressure inert atmosphere. The discrete state of the particles ensures that the surface of each particle can be exposed to the sputtered particle stream during the subsequent deposition process, eliminating coating blind spots. Through the multi-stage throttling structure of the differential pumping transition chamber 2 and the synergistic effect of the independent pumping port 22, a pressure gradient that varies stepwise along the conveying direction is constructed. This mechanism allows discrete powder to pass through continuously while separating and discharging the trace amounts of conveyed gas accompanying the metal powder material in stages, thereby effectively isolating the upstream low-pressure discrete zone from the downstream high-vacuum deposition zone. This precise control of the pressure gradient solves the physical contradiction between trace gas transport and the maintenance of a high-vacuum environment, ensuring the high-vacuum stability of the magnetron sputtering deposition section 3.Discrete powder is conveyed to the magnetron sputtering deposition section 3, which maintains a high vacuum environment. A coating layer is deposited on the surface of continuously flowing powder particles using the physical vapor deposition principle. Because the powder is in a dynamic flow or tumbling state, and the magnetron sputtering targets 31 are arranged in a surrounding pattern, sputtered particles can be uniformly deposited on the particle surface from multiple angles, achieving three-dimensional full-surface coating of micron-sized powder. The high vacuum environment ensures the high purity and high kinetic energy of the deposited particles, improving the bonding strength and density between the coating layer and the substrate. The partially coated metal powder material is returned to the electric field oscillation discrete section 1 via the particle circulation section 4. The electric field oscillation discrete section 1 further disperses any agglomerated particles, and the deposition and circulation steps are repeated. This closed-loop process transforms a single deposition into a progressive thickening process with multiple cycles, making the coating layer thickness increase predictable and repeatable. By adjusting the number of cycles or the circulation speed, the final coating layer thickness can be precisely controlled to meet the differentiated performance requirements of different application scenarios. This invention organically integrates four steps—dispersion, transport, deposition, and circulation—to form a complete closed-loop process. Seamless connections between these steps are achieved through structural design and parameter matching. The initial kinetic energy imparted by the electric field discretization assists powder transport, differential pumping ensures a vacuum environment, and the circulation loop optimizes coating quality. This synergistic effect eliminates the need for manual intervention throughout the entire process, enabling continuous, automated, and intelligent production of metal powder magnetron sputtering coating, significantly improving production efficiency and product consistency. This invention's continuous metal powder magnetron sputtering coating method, through the synergistic effect of four steps—electric field oscillation discretization, differential pumping transition, high-vacuum dynamic deposition, and closed-loop particle circulation—solves the technical problems of easy agglomeration, difficult transport, uneven coating, and difficult thickness control of micron-sized metal powders under high vacuum conditions. It achieves high-quality, high-efficiency, and continuous preparation of metal powder surface coatings, providing a novel process solution for the field of powder surface modification.

[0036] In practice, a continuous coating device for metal powder by magnetron sputtering based on electric field oscillation discreteness is provided, including an electric field oscillation discreteness section 1, a differential pumping transition chamber 2 fixedly installed on the upper side of the electric field oscillation discreteness section 1, a magnetron sputtering deposition section 3 fixedly installed on the upper side of the differential pumping transition chamber 2, and a particle circulation section 4 fixedly installed between the magnetron sputtering deposition section 3 and the electric field oscillation discreteness section 1. The present invention uses the high-voltage electric field formed by the upper electrode plate 12 and the lower electrode plate 11 of the electric field oscillation discreteness section 1 to make the powder particles generate continuous reciprocating oscillation motion between the electrode plates. Under the condition of no mechanical stirring and no high flow rate air intervention, the van der Waals force and electrostatic adsorption force between the powder particles are continuously broken, ensuring that the powder remains in a highly discrete state before entering the magnetron sputtering deposition section 3, thereby significantly improving the coating uniformity.

[0037] The beneficial effects of this invention on the continuous coating device and method for metal powder by magnetron sputtering based on electric field oscillation discreteness are as follows: 1. The present invention uses the high voltage electric field formed by the upper electrode plate 12 and the lower electrode plate 11 of the electric field oscillation discrete section 1 to make the powder particles generate continuous reciprocating oscillation motion between the electrode plates. Under the condition of no mechanical stirring and no high flow rate air intervention, the van der Waals force and electrostatic adsorption force between the powder particles are continuously broken, ensuring that the powder remains highly discrete before entering the magnetron sputtering deposition section 3, thereby significantly improving the coating uniformity.

[0038] 2. On the one hand, the present invention utilizes the electric field oscillation of the discrete section 1 to impart initial kinetic energy to the powder particles, significantly reducing the dependence on auxiliary gas during powder particle transport; on the other hand, a differential pumping transition chamber 2 is provided between the electric field oscillation discrete section 1 and the magnetron sputtering deposition section 3; the differential pumping transition chamber 2 forms a stepped pressure distribution with the independent pumping port 22 through a multi-stage throttling structure, allowing powder particles to pass through continuously while gradually stripping away the transport gas, effectively isolating the low-pressure discrete region and the high-vacuum deposition region, enabling the vacuum chamber 32 of the magnetron sputtering deposition section 3 to maintain a stable high-vacuum environment for a long time, ensuring the deposition quality of the magnetron sputtering target 31.

[0039] 3. This invention abandons the traditional vibration or fluidization method and adopts electric field force as the main dispersion means. Combined with the multi-cycle progressive coating process formed by the particle circulation section 4, it not only ensures that the powder maintains a good dispersion state during continuous processing, but also achieves precise control of the coating thickness. Through the synergistic effect of the above structure, this invention achieves continuous, stable and uniform coating of micron-sized metal powder in a high vacuum environment in a single device, which is significantly better than the existing powder sputtering processing device.

[0040] Example 1: This embodiment uses Al-5Li aluminum-lithium alloy powder with an average particle size of about 30 μm as the processing object to illustrate a typical structure and operating state of achieving continuous and uniform magnetron sputtering coating of micron-sized metal powder under high vacuum conditions using the device of the present invention.

[0041] 1. Overall structure of the device: like Figure 1 and Figure 2 As shown, the device used in this embodiment is a closed continuous processing system arranged in a vertical direction, mainly including an electric field oscillation discrete section 1, a differential pumping transition chamber 2, a magnetron sputtering deposition section 3, and a particle circulation section 4. The functional modules are connected in sequence through sealed flanges to form a complete device that realizes the closed-loop processing of powder "discretion-transportation-deposition-recovery-rediscretion" without damaging the high vacuum of magnetron sputtering.

[0042] 2. Discrete part 1 of electric field oscillation: The electric field oscillation discrete part 1 is located at the bottom of the device. Its function is to physically discrete the powder particles in a low-pressure or vacuum environment and maintain their single-particle dispersion state.

[0043] In this embodiment, the electric field oscillation discrete part 1 includes a lower electrode plate 11 and an upper electrode plate 12 arranged parallel to each other. Both electrodes are made of copper material with a diameter of 200 mm and a distance of 35 mm between them. They are encapsulated in an insulating protective shell 13. The lower electrode plate 11 is connected to the positive terminal of the high-voltage power supply and is used to carry the initial powder particles. The upper electrode plate 12 is connected to the negative terminal of the high-voltage power supply. Several through-holes with a diameter of 120 μm are processed in the central area of ​​the upper electrode plate 12, which are arranged in a regular array.

[0044] When the high-voltage DC power supply is started, a stable strong electric field environment is formed between the two plates. The powder particles gain charge on the surface of the lower plate 11 through contact charging, and move upward under the action of the electric field force. After colliding with the upper plate 12, the charge polarity is reversed, and then they move downward again under the action of the reverse electric field force, thereby generating continuous reciprocating oscillation between the two plates. This oscillation process can effectively overcome the van der Waals forces and electrostatic adsorption forces between powder particles without mechanical stirring, so that the agglomerated powder particles are continuously dispersed and maintained in a discrete state of approximately single particles.

[0045] An air inlet 14 is provided in the central area of ​​the lower electrode plate 11 to introduce a small amount of high-purity inert gas into the discrete zone. The flow rate of this gas needs to be controlled at about 20% of the minimum fluidizing gas volume of the powder particles. The function of the argon gas is to provide a stable and controllable directional driving force to guide the powder particles that have been discrete by the electric field through the sieve holes of the upper electrode plate 12 into the upper structure, without causing the powder bed to reach a fluidized state.

[0046] Discrete powder particles are carried into the differential pumping transition chamber 2 by high-purity inert gas.

[0047] 3. Differential Evacuation Transition Chamber 2: The differential pumping transition chamber 2 is vertically arranged between the electric field oscillation discrete section 1 and the magnetron sputtering deposition section 3. Its main function is to remove the auxiliary gas carried by the powder particles step by step while allowing the powder particles to pass through continuously, thereby structurally isolating the low-pressure area from the high-vacuum area.

[0048] In this embodiment, a three-stage throttling baffle 21 is arranged vertically inside the differential pumping transition chamber 2. Each baffle has a through hole in the center. The diameter of the through hole decreases from bottom to top to match the movement state of the powder particles and reduce the risk of blockage. The baffle divides the interior of the cavity into multiple serial sub-chambers. Each sub-chamber has an independent pumping port 22 on its side wall and is connected to a vacuum pump group with different pumping capacities.

[0049] By independently controlling the gas extraction of each sub-chamber, a stable stepped pressure distribution is established inside the transition chamber. In this embodiment, the pressure of each sub-chamber from bottom to top is maintained at 300Pa, 150Pa, 10Pa and 3Pa respectively. The powder particles pass through each throttling orifice by inertia, while most of the gas is extracted in time at the corresponding level, so that the powder particles before entering the magnetron sputtering deposition section 3 are in a low gas load environment.

[0050] Powder particles enter the magnetron sputtering deposition section 3 by inertia.

[0051] 4. Magnetron sputtering deposition section 3: The magnetron sputtering deposition section 3 is located at the top of the device and is used to deposit a surface thin film on discrete powder particles under high vacuum conditions.

[0052] In this embodiment, the magnetron sputtering deposition section 3 maintains the background vacuum within the vacuum chamber 32 below 3 × 10⁻⁶ using a turbomolecular pump assembly. -3 Pa, the particle inlet 33 at the bottom of the vacuum chamber 32 is used to receive the powder particle flow from the differential pumping transition chamber 2. With the central axis of the particle inlet 33 as the central axis, four planar magnetron sputtering targets 31 are uniformly arranged circumferentially inside the vacuum chamber 32. The target material is high-purity aluminum. The back of each target material integrates a permanent magnet array and a cooling structure to form a stable magnetron sputtering plasma region.

[0053] In the working state of this embodiment, discrete powder particles pass through the sputtering area in the center of the cavity in an almost free motion manner. Each surface of the powder particles is periodically exposed to the sputtering particle stream from different directions, thereby achieving all-round and uniform coating deposition. The deposited powder particles fall into the particle collector 34 set at the bottom of the vacuum cavity 32 under the action of gravity.

[0054] 5. Particle circulation section 4 and feedback control: The particle circulation section 4 is used to re-transport the coated powder particles back to the electric field oscillation and discrete section 1 to achieve multiple cycle processing.

[0055] In this embodiment, a vacuum-locked discharge valve 41 is connected to the lower end of the particle collector 34. The vacuum-locked discharge valve 41 can transfer the coated powder particles to a low-pressure inert atmosphere environment by alternating opening and closing of two gates without disrupting the main vacuum of the magnetron sputtering deposition section 3. The outlet of the vacuum-locked discharge valve 41 is connected to a closed screw feeder 42. The discharge end of the closed screw feeder 42 is connected to the upper part of the lower electrode plate 11 of the electric field oscillation discrete section 1 through an inert gas protection pipeline. A particle concentration monitoring device is set inside the discrete region. The signal of the particle concentration monitoring device and the drive unit of the closed screw feeder 42 form a closed-loop control relationship to achieve dynamic matching between particle concentration and circulation rate.

[0056] 6. Operational performance and parameter adaptability: In this embodiment, the above-mentioned device structure is used to process aluminum-lithium alloy powder with an average particle size of about 30 μm. Under typical working conditions, an aluminum coating layer with an average thickness of about 1.0 μm can be formed after a cumulative processing time of 37 minutes. According to the test, the processed powder particles showed significantly better environmental stability than the uncoated powder particles under high temperature and high humidity conditions. Moreover, under continuous operation conditions, no obvious powder particle agglomeration or blockage was observed inside the system.

[0057] The key structural parameters of the device of the present invention can be adjusted within the following ranges: voltage between the upper electrode 12 and the lower electrode 11 5kV-20kV; electrode spacing 20mm-50mm; auxiliary gas flow rate 5%-50% of the minimum fluidizing gas flow rate of powder particles; differential pumping stages 2-6; environmental pressure before entering the deposition zone preferably below 10Pa; the material, quantity and spatial arrangement of the magnetron sputtering target 31 can be replaced or adjusted according to actual coating requirements.

[0058] Furthermore, during operation, charged powder particles entering the deposition zone exchange charges with the plasma, achieving a dynamic suspension potential. This process helps to further suppress secondary agglomeration of powder particles in the deposition zone. By synergistically optimizing the electric field strength, airflow velocity, and circulation rate, precise control over the charged state and trajectory of powder particles can be achieved, thereby obtaining optimal coating uniformity and system operational stability.

[0059] Example 2: To further illustrate the stability of the device under continuous operation conditions and its effect on improving the uniformity of powder particle coating, spherical aluminum powder with an average particle size of about 25 μm was used as the treatment object, and a nickel coating experiment was conducted in the device of the present invention.

[0060] I. Device Structure and Parameter Settings: The structure of the device in this embodiment is basically the same as that in Embodiment 1. It still adopts a vertically integrated structure from bottom to top, including an electric field oscillation discrete section 1, a differential pumping transition chamber 2, a magnetron sputtering deposition section 3, and a particle circulation section 4. The entire device operates in a closed inert gas protection or vacuum environment to avoid oxidation of powder particles.

[0061] In the electric field oscillation discrete section 1, the distance between the lower electrode plate 11 and the upper electrode plate 12 is set to 30 mm, and the output voltage of the high voltage DC power supply is 12 kV; a small amount of inert gas, preferably high-purity argon, is introduced into the gas nozzle at the center of the lower electrode plate 11, and the gas flow rate needs to be controlled at about 20% of the minimum fluidizing gas volume of the powder particles.

[0062] The differential evacuation transition chamber 2 is equipped with three-stage throttling baffles 21, with the central through holes of each throttling baffle 21 having diameters of 6mm, 4mm and 2mm respectively; each sub-chamber sidewall is connected to an independent evacuation port 22, and a stable pressure gradient is formed by the staged vacuum pump group, so that the internal pressure of the sub-chamber is maintained from bottom to top at 250Pa, 80Pa, 25Pa and 8Pa respectively.

[0063] The magnetron sputtering deposition section 3 employs a stainless steel vacuum chamber 32, which maintains a background vacuum better than 2.5 × 10⁻⁶ via a turbomolecular pump assembly. -3 Pa; Three planar magnetron sputtering targets 31 are set inside the vacuum chamber 32. The target material is high-purity nickel. The target surfaces are uniformly arranged circumferentially with the central axis of the particle inlet 33 as the axis of symmetry. A small amount of argon gas is introduced as the working gas during sputtering. The working pressure inside the vacuum chamber 32 during sputtering is 0.4 Pa, and the working power of each target source is 1.2 kW.

[0064] II. Operation Process and Status Monitoring: During the deposition process, powder particles entering the deposition zone from the differential pumping transition chamber 2 pass through the plasma region in an almost free motion state. Since the particles have been sufficiently dispersed before entering the deposition zone, their surfaces can be periodically exposed to the flow of metal particles from different sputtering targets in all directions, thus forming a uniform deposition. The deposited powder particles fall into the particle collector 34 at the bottom of the vacuum chamber 32 under the action of gravity, and enter the closed screw feeder 42 through the vacuum-locked discharge valve 41. The closed screw feeder 42 re-transports the powder particles to the electric field oscillation discrete section 1 in an inert gas protective environment.

[0065] In this embodiment, the system ran continuously for 3 hours. During the experiment, the key operating parameters of the device were continuously monitored. The results showed that the pressure fluctuation of each level of the sub-chamber of the differential pumping transition chamber 2 was less than ±10%. The system did not show any obvious powder blockage or conveying interruption, and the particle circulation process remained stable.

[0066] III. Assessment of Coating Effect and Operational Reliability: After the operation was completed, the processed powder particles were sampled and analyzed. The scanning electron microscope observation results showed that a continuous and dense nickel coating layer was formed on the surface of the powder particles, and no obvious sintering or agglomeration structure was found between the powder particles. The film thickness was statistically analyzed by randomly selected 120 powder particles. The average thickness of the coating layer was about 0.85 μm and the standard deviation of the thickness was about 0.09 μm, which showed good deposition uniformity.

[0067] The small difference in film thickness at different locations on the powder particle surface indicates that the powder particles are fully exposed to the sputtered particle stream during the deposition process.

[0068] During continuous circulation, by monitoring the changes in particle concentration and circulation rate in the discrete zone, it can be observed that the powder particle circulation flow rate remains stable and no obvious powder particle accumulation occurs in the discrete zone. During system operation, the electric field oscillation discrete part 1 continuously performs re-dispersion processing on the powder particles, effectively avoiding the weak agglomeration structure that may be generated during the deposition process, so that the powder particles always maintain a high degree of dispersion during multiple cycles.

[0069] IV. Experimental Conclusions: The results of this embodiment show that the present invention can stably maintain the high vacuum environment required by the magnetron sputtering deposition section 3 under continuous operation conditions, while realizing the continuous dispersion and cyclic transport of powder particles. Through the synergistic effect between the electric field oscillation dispersion section 1, the differential pumping transition chamber 2, and the particle circulation section 4, the system can not only achieve continuous coating processing of micron-sized powder, but also maintain good operational stability and deposition uniformity during long-term operation, indicating that the device has good potential for engineering applications.

[0070] like Figure 3 As shown, the morphology of metal powder particles after being processed by the magnetron sputtering continuous coating process of this invention is intuitively presented: the core particles maintain a near-spherical (or near-spherical) basic morphology, indicating that the coating process did not destroy the geometric integrity of the original powder; the particle surface is distributed with dense, fine granular protrusions, which are coating layer products formed after the atoms or ions of the magnetron sputtering target are transported in the gas phase and deposited on the surface. The uniform coverage and absence of obvious exposed areas verify the synergistic mechanism of electric field oscillation to ensure particle dispersion, surrounding magnetron sputtering target to ensure full surface deposition, and dynamic flow powder to enhance deposition uniformity, thus achieving three The surface is fully coated (without any uncoated areas or uneven thickness), and the fine-grained growth characteristics of magnetron sputtering deposition are reflected in the morphology of the fine-particle coating layer (submicron to nanometer size) (high kinetic energy and short migration distance of sputtered particles lead to fine particle accumulation). At the same time, the surface coating layer shows no signs of severe sintering or agglomeration, which confirms the effectiveness of the secondary dispersion in the "cyclic dispersion-deposition" closed-loop process (redispersal of agglomerated particles during the cycle). The final coating layer structure is loose and uniform, providing a stable, fully coated, and controllable powder material foundation for subsequent applications (such as catalysis, energy storage, and composite materials).

[0071] Matters not covered in this invention are common knowledge.

[0072] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the 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.

Claims

1. A continuous coating apparatus for metal powder by magnetron sputtering, characterized in that, include: The electric field oscillation discrete part (1) is used to form an alternating high voltage electric field in a low pressure atmosphere, so that the metal powder particles generate reciprocating oscillation motion under the action of electric field force, and continuously overcome the van der Waals force and electrostatic adsorption force between particles in a non-contact manner, thereby realizing the high discreteness of metal powder materials and giving them initial kinetic energy. The differential pumping transition chamber (2) is connected downstream of the electric field oscillation discrete section (1) to construct a pressure gradient that varies stepwise along the conveying direction of the metal powder material, and to separate and discharge the conveying gas accompanying the metal powder material in stages while allowing the discrete metal powder material to pass through continuously. The magnetron sputtering deposition section (3) is connected downstream of the differential pumping transition chamber (2) and is used to deposit a coating layer on the surface of metal powder particles by magnetron sputtering in a high vacuum environment during the continuous passage of discrete powder. The particle circulation section (4) is connected between the magnetron sputtering deposition section (3) and the electric field oscillation discrete section (1). It is used to return the metal powder material coated with some metal powder particles to the electric field oscillation discrete section (1) for multiple cycles, so as to achieve gradual growth and control of coating thickness. Through the synergistic integration of the electric field oscillation discrete section (1), the differential pumping transition chamber (2), the magnetron sputtering deposition section (3), and the particle circulation section (4), a closed-loop processing flow of discrete-transport-deposition-circulation is formed.

2. The continuous coating apparatus for metal powder magnetron sputtering according to claim 1, characterized in that, The electric field oscillation discrete part (1) includes a protective shell (13); The protective shell (13) has an upper electrode plate (12) and a lower electrode plate (11) arranged opposite to each other in the internal cavity. The upper electrode plate (12) and the lower electrode plate (11) are respectively connected to the two poles of the external power supply to connect the alternating high voltage current to build a non-uniform alternating electric field between the upper electrode plate (12) and the lower electrode plate (11). The combination of electric field force and the gravity of the metal powder particles constitutes a periodic action, which forces the metal powder particles to perform high-frequency reciprocating oscillation motion in the gap between the electrodes. By continuously changing the relative position and contact interface between the metal powder particles, the accumulation of van der Waals force and electrostatic adsorption force is blocked, thereby realizing the dynamic discretization of the powder bed. The metal powder particles are given initial kinetic energy to detach from the electrode plate by means of collision and electric field acceleration.

3. The continuous coating apparatus for metal powder magnetron sputtering according to claim 2, characterized in that, The protective shell (13) is provided with an air inlet (14), which extends into the interior space of the protective shell (13) and passes through the lower electrode plate (11) so that the air inlet (14) connects to the discrete area between the upper electrode plate (12) and the lower electrode plate (11); The upper electrode plate (12) has a sieve hole, and the cavity between the upper electrode plate (12) and the lower electrode plate (11) is connected to the internal cavity of the differential pumping transition chamber (2) through the sieve hole; High-purity inert gas is introduced into the discrete zone through the lower electrode plate (11), and the flow rate of the high-purity inert gas is controlled at 10%-30% of the minimum fluidizing gas volume of the metal powder particles. The high-purity inert gas is used to provide a stable and controllable directional driving force, thereby guiding the metal powder particles that have been discrete by the electric field through the sieve holes of the upper electrode plate (12) into the differential pumping transition chamber (2) to prevent the powder bed from entering the fluidized state.

4. The continuous coating apparatus for magnetron sputtering of metal powder according to claim 3, characterized in that, The distance between the upper electrode plate (12) and the lower electrode plate (11) is 20mm-50mm; and / or The external power supply uses a DC power supply with an output voltage of 5kV-20kV; and / or The sieve holes on the upper electrode plate (12) are arranged in an array; and / or The sieve aperture is 50μm-200μm.

5. The continuous coating apparatus for metal powder magnetron sputtering according to claim 1, characterized in that, The differential extraction transition chamber (2) is a hollow cylinder; The differential extraction transition chamber (2) is equipped with multiple throttling baffles (21) arranged at intervals. Each throttling baffle (21) has a central through hole. The throttling baffles (21) divide the differential extraction transition chamber (2) into multiple sub-chambers that are connected sequentially along the conveying direction of the metal powder particles. The diameter of the central through hole of each throttling baffle (21) decreases step by step along the conveying direction of the metal powder particles. The number of sub-chambers is 2 to 6; Each sub-chamber has an independent air extraction port (22) on its side wall.

6. The continuous coating apparatus for metal powder magnetron sputtering according to claim 1, characterized in that, The magnetron sputtering deposition section (3) includes a vacuum chamber (32), and at least one magnetron sputtering target (31) is fixedly installed inside the cavity of the vacuum chamber (32). The lower end of the vacuum chamber (32) is connected to the differential pumping transition chamber (2); A particle collector (34) is also installed at the lower end of the vacuum chamber (32), and the vacuum chamber (32) is connected to the particle circulation section (4) through the particle collector (34); A turbomolecular pump assembly is installed on the vacuum chamber (32).

7. The continuous coating apparatus for metal powder magnetron sputtering according to claim 6, characterized in that, The main body of the particle collector (34) is an inverted oblique cone, and the lowest point of the particle collector (34) is connected to the particle circulation section (4); and / or A particle inlet (33) is provided between the differential pumping transition chamber (2) and the magnetron sputtering deposition section (3). The particle inlet (33) passes through the particle collector (34) and connects the differential pumping transition chamber (2) to the vacuum chamber (32); and / or The magnetron sputtering target (31) is arranged around the central axis of the particle inlet (33).

8. The continuous coating apparatus for magnetron sputtering of metal powder according to any one of claims 1 to 7, characterized in that, The pellet circulation section (4) includes a vacuum-locked discharge valve (41) and a closed screw feeder (42). The vacuum-locked discharge valve (41) is connected to the lowest point of the particle collector (34) of the magnetron sputtering deposition section (3). The end of the vacuum-locked discharge valve (41) away from the particle collector (34) is connected to the closed screw feeder (42) through a pipe. The end of the closed screw feeder (42) away from the vacuum-locked discharge valve (41) is connected to the protective shell (13) of the electric field oscillation discrete section (1) through a pipe. The vacuum-locked discharge valve (41) is a double gate valve.

9. The continuous coating apparatus for magnetron sputtering of metal powder according to any one of claims 1 to 7, characterized in that, The electric field oscillation discrete part (1) is equipped with a particle concentration monitoring device, and the closed screw feeder (42) is electrically connected to the particle concentration monitoring device.

10. A method for continuous coating of metal powder by magnetron sputtering, characterized in that, The continuous coating apparatus for magnetron sputtering of metal powder according to any one of claims 1 to 9 includes the following steps: In the electric field oscillation discrete section (1), a low-pressure inert atmosphere environment is provided. An alternating high-voltage current is applied between the upper electrode (12) and the lower electrode (11) to construct an alternating electric field. After the metal powder material is introduced, the periodic action formed by the combination of electric field force and the gravity of the metal powder particles is used to force the metal powder particles to perform high-frequency reciprocating oscillation motion in the gap between the electrodes. By continuously changing the relative position between the metal powder particles, the accumulation of van der Waals force and electrostatic adsorption force is blocked, thereby realizing the high discreteness of the metal powder material and giving it the initial kinetic energy to detach from the electrode. Discretized metal powder is introduced into differential pumping transition chamber (2). Through the synergistic effect of multi-stage throttling structure and independent pumping port (22), a pressure gradient with step changes along the conveying direction is constructed. While the conveying gas accompanying the metal powder is separated and discharged step by step, the discrete metal powder is allowed to pass through continuously to isolate the low-pressure discrete zone from the high-vacuum deposition zone. Discrete metal powder material passing through the differential pumping transition chamber (2) is transported to the magnetron sputtering deposition section (3), and a coating layer is deposited on the surface of continuously flowing powder particles by magnetron sputtering in a high vacuum environment. The metal powder material that has been partially coated by the magnetron sputtering deposition section (3) is returned to the electric field oscillation and dispersion section (1) through the particle circulation section (4). The agglomerated particles are further dispersed by the electric field oscillation and dispersion section (1), and the deposition and circulation steps are repeated until the coating thickness reaches the preset value, forming a closed-loop processing flow of dispersion-transportation-deposition-circulation.

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