Arc-assisted plasma spraying method and device

Abstract

The invention relates to the technical field of thermal spraying, in particular to an arc-assisted plasma spraying method and device, and the method comprises the following steps: selecting wires of corresponding materials and specifications according to spraying requirements; the two sets of wires are oppositely arranged and fed into a to-be-sprayed area, and the wires are melted through auxiliary electric arcs; a main arc is utilized to excite gas to form plasma, and the plasma blows away the molten wire; and the molten wire blown away by the plasma is sprayed to a workpiece to be sprayed. The device is convenient to use, high in energy utilization rate, low in energy consumption, high in processing efficiency, simple in structure and high in reliability.

Description

Technical Field

[0001] This invention relates to the field of thermal spraying technology, and in particular to an arc-assisted plasma spraying method and apparatus. Background Technology

[0002] Plasma spraying is an advanced coating technology widely used in aerospace, defense, biomedicine, energy, transportation, and many other industries. The principle of plasma spraying is that gas is ionized between electrodes to form a plasma jet, which melts and accelerates powder particles fed into the jet. The melted and accelerated particles impact the substrate and deposit to form a coating with specific functions, such as corrosion resistance, wear resistance, and high-temperature resistance.

[0003] However, due to the low thermal efficiency of plasma jets, less than one-tenth of the plasma energy can be used to melt the raw materials, resulting in low energy utilization efficiency, high process energy consumption, and low material deposition efficiency in plasma spraying technology. The fundamental problems of energy utilization efficiency and processing efficiency in plasma spraying have not yet been solved, leading to persistently high costs.

[0004] Therefore, there is an urgent need to design an arc-assisted plasma spraying method and apparatus to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide an arc-assisted plasma spraying method and apparatus to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: The present invention provides an arc-assisted plasma spraying method, comprising the following steps:

[0007] Select the appropriate material and specifications of wire according to the spraying requirements;

[0008] Two sets of wires are positioned opposite each other and fed into the area to be sprayed, and the wires are melted using an auxiliary electric arc;

[0009] The main electric arc is used to excite the gas to form plasma, which then blows away the molten wire.

[0010] Molten filaments, dispersed by plasma, are sprayed onto the workpiece to be coated.

[0011] Preferably, in the step of selecting the corresponding material and specification of filament according to the spraying requirements, the number of filaments is not less than 2, and the number of filaments is 2n, where n is a natural number not less than 1.

[0012] Preferably, the main arc and the auxiliary arc coexist, and the power of the auxiliary arc is 1 / 8 to 1 / 3 of that of the main arc.

[0013] Preferably, the diameter of the filament is 1.6mm-9mm.

[0014] A spraying apparatus based on an arc-assisted plasma spraying method, comprising:

[0015] The housing serves as the main structure of the device;

[0016] The main electrode is disposed in the housing and is used to generate a main electric arc to ionize the gas and form plasma.

[0017] An auxiliary electrode is disposed in the housing, the filament is fed along the auxiliary electrode, and an auxiliary electric arc is generated between the filaments disposed opposite to each other.

[0018] During operation, the end of the filament that generates the auxiliary electric arc is located in the plasma jet generated by the main electrode.

[0019] Preferably, the main electrode includes a first main anode and a first main cathode correspondingly disposed within the housing. The first main cathode is inserted into the inner cavity of the first main anode and is spaced apart from the first main anode. The first main anode and the first main cathode are electrically connected to a first main power supply disposed outside the housing to form a circuit. The main electric arc is generated between the first main anode and the first main cathode.

[0020] Preferably, the main electrode includes a second main anode, a second main cathode, and a third main cathode correspondingly disposed within the housing. The second main cathode and the third main cathode are symmetrically and obliquely inserted into the inner cavity of the second main anode, and the second main cathode and the third main cathode are respectively spaced apart from the second main anode. The main arc is generated between the second main cathode and the second main anode, and between the third main cathode and the second main anode, respectively.

[0021] Preferably, the second main anode and the second main cathode are electrically connected to a second main power supply disposed outside the housing to form a separate circuit; the second main anode and the third main cathode are electrically connected to a third main power supply disposed outside the housing to form a separate circuit.

[0022] Preferably, the auxiliary electrode includes a plurality of first wire feeding tubes and second wire feeding tubes, which are arranged opposite to each other. The wire passes through the first wire feeding tubes and the second wire feeding tubes respectively and is fed into the plasma jet region. The first wire feeding tubes and the second wire feeding tubes are electrically connected to an auxiliary power supply disposed outside the housing, and the first wire feeding tubes and the second wire feeding tubes are electrically connected to the wire.

[0023] Preferably, the spraying device further includes a wire feeder, which is respectively arranged corresponding to the first wire feed tube and the second wire feed tube, and is used to drive the movement of the wire.

[0024] Compared with existing technologies, this invention has the following advantages and technical effects: This invention discloses an arc-assisted plasma spraying method using filament as raw material. An auxiliary electric arc between the filaments directly acts on the filament to be sprayed. After being heated and melted by the auxiliary arc, the material is blown out by the plasma jet generated by the main arc, forming particles. These particles are simultaneously heated and accelerated, impacting the substrate surface to form a coating, which is then uniformly and firmly fixed to the workpiece surface. The filament melting is completed under the action of anodic and cathodic spots. Furthermore, compared to traditional spraying methods, the particles are heated to a higher temperature in the plasma jet, making it easier to obtain a coating with better bonding performance and improving coating quality. Compared to existing powder raw materials, filament is lower in cost, simpler to operate, and more suitable for continuous processing. This invention is convenient to apply, has high energy utilization, low energy consumption, high processing efficiency, simple structure, and high reliability. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0026] Figure 1 This is a schematic diagram of the arc-assisted plasma spraying device according to Embodiment 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the arc-assisted plasma spraying device according to Embodiment 2 of the present invention;

[0028] In the diagram: 1. Shell; 2. Wire; 3. First main anode; 4. First main cathode; 5. First main power supply; 6. Second main anode; 7. Second main cathode; 8. Third main cathode; 9. Second main power supply; 10. Third main power supply; 11. First wire feeding tube; 12. Second wire feeding tube; 13. Auxiliary power supply; 14. Wire feeder; 15. Jet channel; 16. Air inlet channel. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] Reference Figure 1 As shown, this embodiment provides an arc-assisted plasma spraying method, including the following steps:

[0033] Select the appropriate material and specification of wire according to the spraying requirements;

[0034] Two sets of wires 2 are positioned opposite each other and fed into the area to be sprayed, and the wires 2 are melted by an auxiliary electric arc;

[0035] The main electric arc excites the gas to form plasma, which blows away the molten wire 2; the main electric arc ionizes the gas to form a high-temperature plasma jet, which impacts the end of the wire 2 that has been melted by the auxiliary electric arc, causing it to atomize into molten particles.

[0036] The molten filament 2, dispersed by plasma, is sprayed onto the workpiece to be coated.

[0037] This invention discloses an arc-assisted plasma spraying method using filament 2 as the raw material. An auxiliary electric arc between the filaments 2 acts directly on the filaments to be sprayed. The material is heated and melted by the auxiliary electric arc and then blown out by the plasma jet generated by the main electric arc, forming particles. These particles are simultaneously heated and accelerated, impacting the substrate surface to form a coating, which is then uniformly and firmly fixed to the workpiece surface. The melting of the filament 2 is completed under the action of anodic and cathodic spots. Furthermore, compared to traditional spraying methods, the particles are heated to a higher temperature in the plasma jet, making it easier to obtain a coating with better bonding performance and improving coating quality. Compared to existing powder raw materials, filament 2 is lower in cost, simpler to operate, and more suitable for continuous processing. This invention is convenient to apply, has high energy utilization, low energy consumption, high processing efficiency, simple structure, and high reliability.

[0038] Further optimizing the scheme, in the step of selecting the corresponding material and specification of wire 2 according to the spraying requirements, the number of wire 2 is not less than 2, and the total number of wire 2 is 2n, where n is a natural number not less than 1. The number of wire 2 is even, and every two wires 2 are set up correspondingly. An auxiliary electric arc is generated between two opposing wires 2. The heat from the auxiliary electric arc melts the ends of the wire 2, making it easier for the plasma jet to blow the wire 2 into fine particles.

[0039] In one embodiment of the present invention, the quantity of filament 2 needs to be flexibly selected according to the spraying requirements, and can be increased or decreased in pairs. This is common knowledge in the art and will not be elaborated further.

[0040] Further optimization of the scheme involves the simultaneous presence of a main arc and an auxiliary arc, with the auxiliary arc's power being 1 / 8 to 1 / 3 of that of the main arc. With both arcs operating simultaneously, the auxiliary arc melts the wire 2, while the main arc ionizes the gas to form a plasma jet. This plasma jet is then sprayed onto the auxiliary arc, dispersing the molten wire 2 and completing the coating process. The size of the auxiliary arc controls the melting speed of the wire 2, while the size of the main arc controls the speed of the plasma jet. The auxiliary arc's power is 1 / 8 to 1 / 3 of that of the main arc; this ratio can be selected based on the coating requirements and the specifications of the wire 2 to ensure coating quality.

[0041] In one embodiment of the present invention, more than 50% of the power of the auxiliary electric arc between the wires 2 is used for melting the wires 2, resulting in high energy utilization.

[0042] Further optimization of the scheme involves using wire 2 with a diameter of 1.6mm–9mm. The material and diameter of wire 2 can be selected based on the spraying requirements and equipment model to ensure efficient and high-quality spraying. Those skilled in the art can select the diameter of wire 2 according to their needs; further details are omitted here.

[0043] In one embodiment of the present invention, the wire feeding speed of the wire 2 is directly proportional to the current of the auxiliary arc between the wires 2, which can ensure that the wire 2 is melted efficiently and fully.

[0044] A spraying apparatus based on an arc-assisted plasma spraying method, comprising:

[0045] Housing 1, housing 1 serves as the main structure of the device;

[0046] The main electrode is disposed in the housing 1 and is used to generate the main electric arc to ionize the gas and form plasma.

[0047] An auxiliary electrode is disposed in the housing 1. A wire 2 is fed along the auxiliary electrode, and an auxiliary electric arc is generated between the wires 2 that are disposed opposite to each other.

[0048] During operation, the end of the wire 2 that generates the auxiliary electric arc is located in the plasma jet generated by the main electrode.

[0049] The spraying device mainly consists of a main electrode and an auxiliary electrode set inside the housing 1. The main electrode is used to generate a main electric arc to ionize the gas and form a plasma jet. The auxiliary electrode is located inside the housing 1 in the direction of the plasma jet ejection. It is used to feed the wire 2 and generate an auxiliary electric arc between the opposite wires 2 to melt the ends of the wire 2. The wire 2 in the plasma jet is melted and blown onto the workpiece.

[0050] In one embodiment of the present invention, the main electrode, the auxiliary electrode and the wire 2 are all mounted on the housing 1. There is a water cooling channel between the housing 1 and the main electrode to cool the device and avoid affecting the device performance.

[0051] In one embodiment of the present invention, the housing 1 has a duct that connects to the inner cavity of the main electrode, and the plasma jet is ejected from the outlet of the duct.

[0052] A further optimized scheme includes a first main anode 3 and a first main cathode 4 correspondingly disposed within the housing 1. The first main cathode 4 is inserted into the inner cavity of the first main anode 3 and spaced apart from it. The first main anode 3 and the first main cathode 4 are electrically connected to a first main power supply 5 disposed outside the housing 1 to form a circuit. A main electric arc is generated between the first main anode 3 and the first main cathode 4. (Refer to...) Figure 1 As shown, this embodiment includes a cathode and an anode, namely a first main anode 3 and a first main cathode 4. The first main anode 3 and the first main cathode 4 are electrically connected to the first main power supply 5 to form a circulating circuit. The first main cathode 4 is located above the auxiliary arc. The main arc is generated between the first main cathode 4 and the first main anode 3, generating a plasma jet. The plasma jet passes through the auxiliary arc.

[0053] In one embodiment of the present invention, the first main anode 3 is designed in a tubular shape, and its inner cavity is provided with a jet channel 15. The top end of the jet channel 15 is connected to an air intake channel 16. The first main cathode 4 is inserted into the air intake channel 16 from the top end of the first main anode 3 and is spaced apart. A gap is left between the first main anode 3 and the first main cathode 4 in the air intake channel 16 for air intake. The main electric arc is also generated in the air intake channel 16. When the airflow passes through the air intake channel 16, it is ionized by the main electric arc to form a plasma jet, which then enters the jet channel 15. The two opposing wires 2 are located in the jet channel 15 and generate an auxiliary electric arc to melt the ends of the wires 2. The wires 2 are blown toward the workpiece surface by the plasma jet passing through the jet channel 15.

[0054] In a further optimized design, the auxiliary electrode includes several first wire feeding tubes 11 and second wire feeding tubes 12, which are arranged opposite to each other. Wire 2 passes through the first wire feeding tubes 11 and second wire feeding tubes 12 and is fed into the plasma jet region. The first wire feeding tubes 11 and second wire feeding tubes 12 are electrically connected to an auxiliary power supply 13 located outside the housing 1, and are also electrically connected to the wire 2. The first wire feeding tubes 11 and second wire feeding tubes 12 pass through the outer walls of the housing 1 and the first main anode 3 and extend into the jet channel 15. Wire 2 is fed into the jet channel 15 through the first wire feeding tubes 11 and second wire feeding tubes 12. Simultaneously, the first wire feeding tubes 11 and second wire feeding tubes 12 are connected to the two poles of the auxiliary power supply 13 and energize the wire 2, generating an auxiliary electric arc between the opposing wires 2, melting the wire 2 located in the jet channel 15 at a set speed.

[0055] To further optimize the design, the spraying device also includes a wire feeder 14, which is correspondingly configured with the first wire feeding tube 11 and the second wire feeding tube 12 to drive the movement of the wire 2. The current connected to the first wire feeding tube 11 and the second wire feeding tube 12 is interlocked with the wire feeder 14, which can control the operating speed of the wire feeder 14. By adjusting the current, the speed of the wire feeder 14 changes accordingly, ensuring that the wire feeding speed corresponds to the melting speed of the wire 2.

[0056] In one embodiment of the present invention, the wire 2 is both a raw material and a conductor for melting the heat source of the wire 2 and a carrier for forming an auxiliary electric arc. The first wire feeding tube 11 and the second wire feeding tube 12 are connected to the same auxiliary power supply 13, and the tips of the two wires 2 form an auxiliary electric arc.

[0057] In one embodiment of the present invention, the parameters of the first wire feeding tube 11 and the second wire feeding tube 12 are the same, the only difference being that one is connected to the anode of the auxiliary power supply 13 and the other is connected to the cathode of the auxiliary power supply 13.

[0058] In one embodiment of the present invention, the number of filament 2 guide tubes is the same as that of filament 2, which is an even number, and more preferably, the number is 2.

[0059] In one embodiment of the present invention, the diameter of the filament 2 guide tube is between 1.5 mm and 9.5 mm.

[0060] In one embodiment of the present invention, the filament 2 is divided into three types according to actual needs: solid filament, powder core filament, or twisted filament. During the spraying process, the type of filament 2 is one or a combination of the three types. Those skilled in the art can choose according to their needs, which will not be elaborated here.

[0061] In one embodiment of the present invention, an auxiliary electric arc is formed between the tips of the two wires 2 arranged opposite to each other, and the included angle between the tips of the two wires 2 forming the electric arc is α, 40°≤α≤180°.

[0062] In one embodiment of the present invention, the wire feeding speed is preferably controlled by the power supply of the auxiliary electrode.

[0063] In one embodiment of the present invention, the first main power supply 5 and the auxiliary power supply 13 are preferably DC power supplies and are independent of each other.

[0064] In one embodiment of the present invention, the first main power supply 5 is a DC power supply with a steep drooping external characteristic. It is a conventional device and will not be described in detail here.

[0065] In one embodiment of the present invention, the auxiliary power supply 13 is preferably a power supply with flat external characteristics, which is a conventional device and will not be described in detail here.

[0066] Specific examples:

[0067] Coatings containing ceramic phases, such as NiCr+WC and NiCr+ZrO2, are costly and inefficient to process using powder materials, and the ceramic phase is prone to property degradation due to heat. Using the spraying apparatus of this embodiment, coatings can be processed at low cost and high efficiency, without overheating the ceramic phase.

[0068] Specifically, this device employs one primary cathode 4 and two powder-core wires with identical chemical compositions as the wire material 2, both with a diameter of 3.0 mm and an included angle of 100°. The outer sheath of the powder-core wire 2 is made of NiCr alloy, and the inner powder core is a mixture of powders containing WC and ZrO2. The outer sheath of the wire material 2 melts and encapsulates the internal ceramic phase, depositing it onto the substrate. The ceramic phase is not heated by the electric arc, thus its performance is not degraded. The primary power supply 5 exhibits a steep descent characteristic, while the auxiliary power supply 13 exhibits a flat characteristic. The wire feeder 14 is coupled to the auxiliary power supply 13. A mixture of argon and hydrogen is used as the plasma gas, with a flow rate of 90 L / min. The main arc power is 25 kW, the spraying distance is 120 mm, and the auxiliary arc power is 4 kW. The spraying efficiency of the NiCr+WC coating is 10–15 kg / h.

[0069] Example 2

[0070] Reference Figure 2As shown, the difference between this embodiment and Embodiment 1 is only that the main electrode includes a second main anode 6, a second main cathode 7, and a third main cathode 8 correspondingly disposed within the housing 1. The second main cathode 7 and the third main cathode 8 are symmetrically and obliquely inserted into the inner cavity of the second main anode 6, and the second main cathode 7 and the third main cathode 8 are respectively spaced apart from the second main anode 6; a main arc is generated between the second main cathode 7 and the second main anode 6, and between the third main cathode 8 and the second main anode 6; the second main anode 6 and the second main cathode 7 are electrically connected to the second main power supply 9 disposed outside the housing 1 to form a separate circuit; the second main anode 6 and the third main cathode 8 are electrically connected to the third main power supply 10 disposed outside the housing 1 to form a separate circuit. (Refer to...) Figure 2 As shown, this embodiment includes multiple cathodes and one anode, namely a second main anode 6, a second main cathode 7 and a third main cathode 8. The second main cathode 7 and the third main cathode 8 are inserted into the top of the second main anode 6. At the same time, the second main anode 6 and the second main cathode 7 are connected to the second main power supply 9 to form a circuit, and the second main anode 6 and the third main cathode 8 are connected to the third main power supply 10 to form a circuit, respectively forming a main electric arc to generate a jet for the incoming gas.

[0071] In one embodiment of the present invention, the second main anode 6 is arranged in a tubular shape, and a jet channel 15 is provided inside it. Several sets of opposing wires 2 are arranged opposite each other and are laterally fed into the jet channel 15. The arrangement and parameter adjustment of the auxiliary electrode are the same as in Embodiment 1, and will not be repeated here.

[0072] In one embodiment of the present invention, the top end of the jet channel 15 is connected to a plurality of air intake channels 16 corresponding to the second main cathode 7 and the third main cathode 8. The second main cathode 7 and the third main cathode 8 are respectively inserted into the corresponding air intake channels 16 and are spaced apart. A main electric arc is formed in the air intake channel 16 to ionize the gas entering the air intake channel 16 to form a plasma jet, which then converges into the jet channel 15 and carries the granular molten wire 2 out of the outlet of the jet channel 15.

[0073] In one embodiment of the present invention, the number of cathodes is ≥2, and is not limited to the second main cathode 7 and the third main cathode 8 disclosed in this embodiment. The air intake channel 16 and the power supply correspond to the cathodes. Those skilled in the art can select them according to actual needs, which will not be elaborated here.

[0074] Specific examples:

[0075] Nickel-aluminum alloys have high specific strength and strong corrosion resistance, but they are also brittle. The large difference in melting points between nickel and aluminum makes it difficult to process this alloy through casting, forging, or other methods. However, this example demonstrates how to easily manufacture a nickel-aluminum coating. Two cathodes and one anode are used. The anode contains two air inlet channels 16 and one jet channel 15, with the included angle between the air inlet channels 16 and the jet channel 15 both at 30°.

[0076] Two solid wires (2) are used, one pure nickel and the other pure aluminum, both 2mm in diameter, with a 40° angle between them. Two power sources are needed to generate the plasma jet: a second main power source (9) and a third main power source (10), both with steeply sloping external characteristics. The auxiliary arc power source (13) has a flat external characteristic. A mixture of argon and hydrogen is used as the plasma gas, with a flow rate of 80L / min. The main arc power is 30kW, the spraying distance is 120mm, and the auxiliary arc power is 4kW. The wire feeder (14) has a separately controlled speed, not coupled to the auxiliary arc power source. Aluminum wire has a low melting point and melts quickly, so its feeding speed is greater than that of nickel wire. The coating efficiency of the nickel-aluminum coating is 7-9 kg / h.

[0077] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0078] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An arc-assisted plasma spraying method, characterized in that, The method comprises the following steps: selecting the corresponding material and specification of the wire (2) according to the spraying requirement; two groups of the wire (2) are oppositely arranged and sent to the area to be sprayed, and the wire (2) is melted by using the auxiliary arc; the main arc is used to excite the gas to form the plasma, and the plasma blows away the melted wire (2); the melted wire (2) blown away by the plasma is sprayed on the workpiece to be sprayed.

2. The arc-assisted plasma spraying method according to claim 1, characterized in that: In the step of selecting the corresponding material and specification of the wire (2) according to the spraying requirement, the number of the wire (2) is not less than 2, and the number of the wire (2) is 2n, wherein n is a natural number not less than 1.

3. The arc-assisted plasma spraying method according to claim 1, characterized in that: The main arc and the auxiliary arc exist simultaneously, and the power of the auxiliary arc is 1 / 8 to 1 / 3 of the power of the main arc.

4. The arc-assisted plasma spraying method according to claim 1, characterized in that: The diameter of the wire (2) is 1.6mm-9mm.

5. An arc-assisted plasma spraying apparatus based on the arc-assisted plasma spraying method according to any one of claims 1 to 4, characterized in that The device comprises: a shell (1) as the main structure of the device; a main electrode arranged in the shell (1), which is used to generate a main arc and ionize the gas to form a plasma; an auxiliary electrode arranged in the shell (1), the wire (2) is sent along the auxiliary electrode, and the auxiliary arc is generated between the oppositely arranged wires (2); During operation, the end of the wire (2) generating the auxiliary arc is located in the plasma jet generated by the main electrode.

6. The arc-assisted plasma spraying apparatus of claim 5, wherein: The main electrode comprises a first main anode (3) and a first main cathode (4) arranged in the shell (1) correspondingly, the first main cathode (4) is inserted into the inner cavity of the first main anode (3) and arranged with a gap from the first main anode (3), and the first main anode (3) and the first main cathode (4) are electrically connected with a first main power supply (5) arranged outside the shell (1) to form a loop; the main arc is generated between the first main anode (3) and the first main cathode (4).

7. The arc-assisted plasma spraying apparatus of claim 5, wherein: The main electrode comprises a second main anode (6), a second main cathode (7) and a third main cathode (8) arranged in the shell (1) correspondingly, the second main cathode (7) and the third main cathode (8) are symmetrically and obliquely inserted into the inner cavity of the second main anode (6), and the second main cathode (7) and the third main cathode (8) are arranged with a gap from the second main anode (6) respectively; the second main cathode (7) and the second main anode (6) and the third main cathode (8) and the second main anode (6) generate the main arc respectively.

8. The arc-assisted plasma spraying apparatus of claim 7, wherein: The second main anode (6) is electrically connected with the second main cathode (7) and a second main power supply (9) arranged outside the shell (1) to form a separate loop; the second main anode (6) and the third main cathode (8) are electrically connected with a third main power supply (10) arranged outside the shell (1) to form a separate loop.

9. The arc-assisted plasma spraying apparatus of claim 5, wherein: The auxiliary electrode comprises a plurality of first wire feeding pipes (11) and second wire feeding pipes (12), the first wire feeding pipes (11) and the second wire feeding pipes (12) are oppositely arranged, and the wire material (2) passes through the first wire feeding pipes (11) and the second wire feeding pipes (12) to enter the plasma jet area; the first wire feeding pipes (11) and the second wire feeding pipes (12) are electrically connected with an auxiliary power supply (13) arranged outside the shell (1), and the first wire feeding pipes (11) and the second wire feeding pipes (12) are electrically connected with the wire material (2) respectively.

10. The arc-assisted plasma spraying apparatus of claim 9, wherein: The spraying device further comprises a wire feeder (14) corresponding to the first wire feeding pipe (11) and the second wire feeding pipe (12), which is used for driving the movement of the wire material (2).

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