JP7278174B2 - PLASMA SPRAYING APPARATUS AND PLASMA SPRAYING METHOD - Google Patents

Description

The present disclosure relates to a plasma spraying apparatus and a plasma spraying method.

Plasma spraying is known, in which powder particles used for thermal spraying are melted by the heat of a plasma jet formed from high-speed gas and ejected toward the surface of a substrate to form a coating on the surface of the substrate ( For example, see Patent Documents 1 to 4).

JP-A-6-325895 JP-A-8-225916 Patent No. 5799153 JP 2014-172696 A

The present disclosure provides techniques that can control the shape of the plasma jet.

A plasma spraying apparatus according to an aspect of the present disclosure includes: a supply unit that carries a powder of a thermal spray material by a first gas and injects it from an opening at a tip; a plasma generation unit for generating plasma having a common core; a gas flow path for supplying a second gas forming a swirling flow with a central axis of the supply unit as a swirling axis in the plasma generation space; a magnetic field generator that generates a magnetic field parallel to the central axis of the supply unit in the generation space.

According to the present disclosure, the shape of the plasma jet can be controlled.

Diagram showing an example of the overall configuration of a plasma spraying apparatus A diagram showing an example of a magnetic field generating part of a plasma spraying apparatus The figure which shows another example of the magnetic field generation part of a plasma spraying apparatus The figure which shows another example of the magnetic field generation part of a plasma spraying apparatus Diagram (1) for explaining the force that Ar ⁺ forming a swirling flow receives from a magnetic field Diagram (2) for explaining the force that Ar ⁺ forming a swirling flow receives from a magnetic field Diagram (3) for explaining the force that Ar ⁺ forming a swirling flow receives from the magnetic field Figure (1) showing simulation results of magnetic field distribution Figure (2) showing simulation results of magnetic field distribution Figure (3) showing simulation results of magnetic field distribution Flowchart showing an example of a plasma spraying method A diagram showing the evaluation results of the shape of the plasma jet and the amount of thermal spray coating Figure showing evaluation results of anode-cathode voltage

Non-limiting exemplary embodiments of the present disclosure will now be described with reference to the accompanying drawings. In all the attached drawings, the same or corresponding members or parts are denoted by the same or corresponding reference numerals, and overlapping descriptions are omitted.

[Plasma spraying equipment]
FIG. 1 is a diagram showing an example of the overall configuration of a plasma spraying apparatus 1. As shown in FIG. As shown in FIG. 1, the plasma spraying apparatus 1 sprays powder of a thermal spraying material (hereinafter referred to as "thermal spraying powder R1") from an opening 11b at the tip of a nozzle 11, and uses high-speed gas. It is an apparatus for forming a film F1 on the surface of the base material W by blowing out toward the surface of the base material W while being melted by the heat of the formed plasma jet P.

The plasma spraying apparatus 1 includes a supply section 10 , a control section 30 , a gas supply section 40 , a plasma generation section 60 and a magnetic field generation section 80 .

The supply unit 10 has a nozzle 11 and a feeder 20, carries the thermal spraying powder R1 with the plasma generating gas, and injects it from the opening 11b at the tip. The particle size of the thermal spray powder R1 is, for example, 1 μm to 10 μm.

The feeder 20 supplies the thermal spraying powder R1 to the nozzle 11 . The thermal spraying powder R1 is stored in a container 21 inside the feeder 20. As shown in FIG. The thermal spraying powder R1 may be, for example, metal fine powder such as copper (Cu), lithium (Li), iron (Fe), aluminum (Al), nickel (Ni), molybdenum (Mo). Further, the thermal spraying powder R1 may be a fine powder of a resin such as polyester. The thermal spraying powder R1 is ceramics such as alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), mullite (Al ₆ O ₁₃ Si ₂ ), spinel (MgAl ₂ O ₄ ), or composite materials of these ceramics. It may be a fine powder.

The feeder 20 is provided with an actuator 22 . The nozzle 11 is a rod-shaped annular member, and a flow path 11a is formed therein through which the thermal spraying powder R1 is conveyed. The flow path 11 a of the nozzle 11 communicates with the inside of the container 21 , and the power of the actuator 22 causes the thermal spraying powder R<b>1 to enter the flow path 11 a from the container 21 .

A plasma generating gas is supplied to the nozzle 11 as a first gas together with the thermal spraying powder R1. A plasma-generating gas is a gas for generating plasma. The plasma-generating gas also functions as a carrier gas that carries the thermal spray powder R1 in the flow path 11a. The gas supply unit 40 supplies the plasma generating gas from the gas supply source 41 . The plasma generating gas is flow-controlled through a valve 46 and a mass flow controller (MFC) 44 and supplied through a pipe 42 to the flow path 11a. Argon (Ar) gas, nitrogen (N ₂ ) gas, helium (He) gas, and a mixture of these gases can be used as the plasma generating gas. In the following, the case of using Ar gas as the plasma generation gas will be described as an example.

The nozzle 11 has a structure in which the main body 12 of the plasma generating section 60 is penetrated and the tip thereof protrudes into the plasma generating space U. As shown in FIG. The thermal spraying powder R1 is carried to the tip of the nozzle 11 by the plasma generating gas, and is injected into the plasma generating space U from the opening 11b of the tip along with the plasma generating gas.

The body portion 12 is made of a resin material. The body portion 12 has a through hole 12a in its central portion. A front portion 11 c of the nozzle 11 is inserted into the through-hole 12 a of the body portion 12 . A front portion 11 c of the nozzle 11 is connected to a DC power supply 50 and also functions as an electrode (cathode) to which current is applied from the DC power supply 50 . The nozzle 11 is made of metal.

The plasma generating space U is a space formed by the recessed portion 12b and the projecting portion 12d of the main body portion 12, and the tip portion of the nozzle 11 protrudes into the plasma generating space U. As shown in FIG. The projecting portion 12d is connected at one end to a metal plate 12c provided on the outer wall of the body portion 12 . Metal plate 12 c is connected to DC power supply 50 . Thereby, the metal plate 12c and the projecting portion 12d function as an electrode (anode).

As a result, the tip of the nozzle 11 and the other end of the projecting portion 12d function as cathode and anode electrodes, and discharge occurs. As a result, the Ar gas injected from the nozzle 11 is ionized, and plasma is generated in the plasma generating space U. As shown in FIG.

Ar gas is supplied to the plasma generation space U as a swirling flow as the second gas. Ar gas is supplied from a gas supply source 41, is flow-controlled through a valve 46 and a mass flow controller (MFC) 45, flows through the main body 12 through a pipe 43, which is a gas flow path, and generates plasma from the lateral direction. space U. As a result, a swirl flow is formed in the plasma generation space U with the center axis O of the supply unit 10 as the swirl axis.

In FIG. 1, only one Ar gas supply channel introduced into the plasma generating space U is illustrated, but the main body 12 is provided with a plurality of supply channels. As a result, the Ar gas is supplied to the plasma generation space U from the plurality of supply passages as a laterally swirling flow. This prevents diffusion of the generated plasma and causes the plasma jet P to be linearly deflected. As a result, the plasma generation unit 60 uses the plasma generating gas injected from the tip of the nozzle 11 to generate the plasma jet P having a common axis with the nozzle 11 . In one embodiment, "having a common axis" means that the central axis O of the supply unit 10 (nozzle 11) and the central axis of the direction in which the plasma jet P is blown match or almost match in the same direction. Say.

In the plasma spraying apparatus 1, the supply unit 10 advances the thermal spraying powder R1 and the Ar gas straight through the flow path 11a formed inside the nozzle 11, and injects them into the plasma generation space U from the opening 11b at the tip. The sprayed thermal spraying powder R1 is sprayed toward the surface of the substrate W while being melted by the heat of the plasma jet P formed by high-speed Ar gas, forming a coating F1 on the surface of the substrate W by thermal spraying. . At this time, thermal spraying may be performed while moving the substrate W, or may be performed while moving the nozzle 11 . When thermal spraying is performed while moving the substrate W, for example, thermal spraying can be performed while horizontally moving a stage (not shown) on which the substrate W is placed. When thermal spraying is performed while moving the nozzle 11, for example, the supply unit 10 can be fixed to a horizontally movable arm (multi-joint arm), and thermal spraying can be performed while moving the supply unit 10 in the horizontal direction by the arm. .

A magnetic field generating section 80 for generating a magnetic field in the plasma generating space U is provided in the outer peripheral portion of the plasma generating space U. As shown in FIG. The magnetic field generator 80 is arranged below the front portion 11c of the nozzle 11 that functions as a cathode, for example. The magnetic field generator 80 generates a magnetic field having a desired distribution with respect to the central axis O of the supply section 10 in the plasma generation space U. As shown in FIG. The desired distribution of the magnetic field preferably includes a magnetic field distribution formed along the central axis O below the tip of the nozzle 11 in a substantially vertical direction (Z direction). However, the desired distribution of the magnetic field is not limited to this. A magnetic field distribution formed below the tip of the nozzle 11 in a fan shape or tapered shape with respect to the central axis O may also be included.

The magnetic field generator 80 has, for example, an annular (ring-shaped) permanent magnet centered on the central axis O of the supply unit 10 . The permanent magnet may be fixed to the body portion 12 or may be movable in the direction of the central axis O of the supply portion 10 . Also, the number of permanent magnets may be one or plural. When there are a plurality of permanent magnets, they are arranged at intervals in the direction of the central axis O of the supply section 10, for example. Further, the magnetic field generator 80 may have an electromagnet including a coil centered on the central axis O of the supply section 10 . The number of electromagnets may be one or plural. When there are a plurality of electromagnets, they are arranged at intervals in the direction of the central axis O of the supply section 10, for example. Further, the magnetic field generating section 80 includes one or more annular permanent magnets centered on the central axis O of the supply section 10 and one or more electromagnets including coils centered on the central axis O of the supply section 10. , may have Details of the magnetic field generator 80 will be described later.

A coolant channel 72 is formed inside the body portion 12 . The refrigerant supplied from the chiller unit 70 circulates through the valve 74 , the refrigerant pipe 71 , the refrigerant flow path 72 , the refrigerant pipe 73 and the valve 75 in this order, and returns to the chiller unit 70 . As a result, the body portion 12 is cooled, and the body portion 12 can be prevented from becoming hot due to the heat of the plasma. A flow meter (FM) 76 provided between the valve 74 and the refrigerant pipe 71 controls the temperature of the main body 12 to be constant.

The plasma spraying apparatus 1 is provided with a control section 30, for example, a computer. The control unit 30 includes a program, a memory, a data processing unit including a CPU, and the like. The program incorporates commands to send control signals from the control unit 30 to each unit of the plasma spraying apparatus 1 to execute plasma spraying. The control signal controls the operations of the gas supply source 41, the feeder 20 (actuator 22), the DC power supply 50, the chiller unit 70, etc., and the process of forming the film F1 on the surface of the substrate W is performed. The program is stored in a computer storage medium such as a flexible disk, a compact disk, a hard disk, an MO (magneto-optical disk), a memory card, or the like, and installed in the controller 30 .

[Magnetic field generator]
FIG. 2 is a diagram showing an example of the magnetic field generator 80 of the plasma spraying apparatus 1. As shown in FIG. As shown in FIG. 2 , the magnetic field generator 80 has annular permanent magnets 81 a , 81 b , 81 c centered on the central axis O of the supply section 10 .

The permanent magnets 81a, 81b, and 81c are arranged in the outer peripheral portion of the plasma generation space U at intervals in the direction of the central axis O of the supply section 10 (the Z direction in FIG. 2). The permanent magnets 81a, 81b, 81c are provided inside the main body 12, for example. The permanent magnets 81 a , 81 b , 81 c generate a magnetic field parallel to the central axis O of the supply section 10 in the plasma generation space U. The permanent magnets 81a, 81b, and 81c may all have the same magnetic force, or may have different magnetic forces. The permanent magnets 81a, 81b, 81c are neodymium magnets, for example.

Although the example of FIG. 2 shows the case where the permanent magnets 81a, 81b, 81c are provided inside the main body 12, the arrangement of the permanent magnets 81a, 81b, 81c is not limited to this. For example, at least one of the permanent magnets 81a, 81b, 81c may be arranged below the projecting portion 12d of the main body portion 12. In this case, a magnetic field parallel to the central axis O of the supply section 10 can also be generated in the space below the plasma generation space U by the permanent magnet arranged below the projecting section 12d of the main body section 12 .

FIG. 3 is a diagram showing another example of the magnetic field generator 80 of the plasma spraying apparatus 1. As shown in FIG. As shown in FIG. 3, the magnetic field generating section 80 raises and lowers the permanent magnets 82a to 82e centered on the central axis O of the supply section 10 and the permanent magnets 82a to 82e along the central axis O of the supply section 10 ( and a lifting mechanism 82f for moving.

The permanent magnets 82a to 82e are arranged on the outer periphery of the plasma generation space U at intervals in the direction of the central axis O of the supply section 10 (the Z direction in FIG. 3). The permanent magnets 82 a to 82 e are movable and can move in the direction of the central axis O of the supply section 10 . Thereby, the length of the magnetic field parallel to the central axis O of the supply unit 10 generated in the plasma generation space U can be controlled. For example, as shown in FIG. 3A, narrowing the distance between the permanent magnets 82a to 82e reduces the length of the magnetic flux line parallel to the central axis O of the supply unit 10, but increases the magnetic force. Therefore, a thin, high-density plasma jet P can be generated. On the other hand, as shown in FIG. 3B, for example, when the intervals between the permanent magnets 82a to 82e are increased, the magnetic force is weakened, but the length of the magnetic flux line parallel to the central axis O of the supply unit 10 is increased. A long and stable plasma jet P can be generated. The permanent magnets 82a-82e are, for example, neodymium magnets.

The elevating mechanism 82f elevates the permanent magnets 82a to 82e along the central axis O of the supply section . The lifting mechanism 82f is fixed to, for example, a metal plate 12c provided on the outer wall of the main body 12. As shown in FIG. The lifting mechanism 82f is controlled by the controller 30, for example. The lifting mechanism 82f includes, for example, a motor.

FIG. 4 is a diagram showing still another example of the magnetic field generator 80 of the plasma spraying apparatus 1. As shown in FIG. As shown in FIG. 4, the magnetic field generator 80 has electromagnets 83a, 83b, and 83c.

The electromagnets 83a, 83b, 83c include coils 83a1, 83b1, 83c1 centering on the central axis O of the supply unit 10, variable power supplies 83a2, 83b2, 83c2, and wires 83a3, 83b3, 83c3.

The coils 83a1, 83b1, 83c1 are arranged in the outer peripheral portion of the plasma generation space U at intervals in the direction of the central axis O of the supply section 10 (the Z direction in FIG. 4). The coils 83a1, 83b1, 83c1 are provided inside the main body 12, for example. The coils 83a1, 83b1, and 83c1 generate a magnetic field parallel to the central axis O of the supply section 10 in the plasma generation space U by energizing them.

Although the example of FIG. 4 shows the case where the coils 83a1, 83b1, 83c1 are provided inside the main body 12, the arrangement of the coils 83a1, 83b1, 83c1 is not limited to this. For example, at least one of the coils 83 a 1 , 83 b 1 , 83 c 1 may be arranged below the projecting portion 12 d of the body portion 12 . In this case, the magnetic field parallel to the central axis O of the supply section 10 can also be generated in the space below the plasma generation space U by the coil arranged below the projecting section 12d of the main body section 12 .

The variable power sources 83a2, 83b2, 83c2 supply currents to the coils 83a1, 83b1, 83c1 through wirings 83a3, 83b3, 83c3, respectively. By adjusting the values and directions of currents to be supplied to the coils 83a1, 83b1, and 83c1 by the variable power sources 83a2, 83b2, and 83c2, the distribution of the magnetic field parallel to the central axis O of the supply section 10 generated in the plasma generation space U can be controlled. . The variable power sources 83a2, 83b2, 83c2 are controlled by the control section 30, for example.

Wirings 83a3, 83b3, 83c3 electrically connect coils 83a1, 83b1, 83c1 and variable power supplies 83a2, 83b2, 83c2, respectively.

[Control of plasma jet shape]
FIG. 5 is a diagram for explaining the force that the argon ions (Ar ⁺ ) forming the swirling flow receive from the magnetic field. and the direction of the force that Ar ⁺ receives from the magnetic field. 6 and 7 are diagrams for explaining the force that Ar ⁺ forming the swirling flow receives from the magnetic field. , the direction of the swirling flow, and the direction of the force F that Ar ⁺ receives from the magnetic field.

First, as shown in FIG. 5, annular permanent magnets M1 and M2 centered on the central axis O of the supply unit 10 (nozzle 11) are spaced apart in the direction of the central axis O, and the thermal spraying powder R1 is Consider the case where the upstream side in the injection direction is the S pole and the downstream side is the N pole. More specifically, the thermal spraying powder R1 is placed around the central axis O of the supply unit 10 at a position substantially at the same height as the opening 11b at the tip of the nozzle 11 in the outer peripheral portion of the plasma generation space U. The permanent magnet M1 is arranged so that the upstream side in the ejection direction is the S pole and the downstream side is the N pole. Further, in the outer peripheral portion of the plasma generating space U and below the opening 11b at the tip of the nozzle 11, the upstream side of the injection direction of the thermal spraying powder R1 centered on the central axis O of the supply unit 10 is S. The permanent magnet M2 is arranged so that the pole, the downstream side, is the north pole.

In this case, the direction of the magnetic flux lines Mf (magnetic field B) in the plasma generation space U is the direction from the downstream side to the upstream side (- Z direction). When the direction of the magnetic flux lines Mf in the plasma generating space U is the direction from the downstream side to the upstream side of the spraying direction of the thermal spraying powder R1, the spraying direction of the thermal spraying powder R1 is as shown in FIGS. Ar ^{2 +} contained in the clockwise swirling flow (hereinafter referred to as “right-handed swirling flow”) receives a force F in the direction of approaching the central axis O of the supply unit 10 due to the magnetic field B. As shown in FIG. As a result, Ar ⁺ moves toward the central axis O. As shown in FIG. Therefore, the shape of the plasma jet P is elongated in the Z direction, and the plasma density increases in the vicinity of the central axis O of the supply section 10 through which the thermal spraying powder R1 passes. As a result, the efficiency of heat input to the thermal spray powder R1 is improved, and the efficiency and quality of the thermal spray film are improved. In addition, since the plasma moves away from the inner wall of the main body 12, damage to the main body 12 due to plasma is suppressed, and the life of the main body 12 is extended.

On the other hand, consider the case where the permanent magnets M1 and M2 in FIG. 5 are arranged with their N poles and S poles reversed. More specifically, the thermal spraying powder R1 is placed around the central axis O of the supply unit 10 at a position substantially at the same height as the opening 11b at the tip of the nozzle 11 in the outer peripheral portion of the plasma generation space U. The permanent magnet M1 is arranged so that the upstream side in the ejection direction is the N pole and the downstream side is the S pole. In addition, in the outer periphery of the plasma generating space U and below the opening 11b at the tip of the nozzle 11, N The permanent magnet M2 is arranged so that the pole, the downstream side, is the S pole.

In this case, the direction of the magnetic flux lines Mf (magnetic field B) in the plasma generation space U is along the central axis O of the supply unit 10 from the upstream side to the downstream side of the injection direction of the thermal spray powder R1 (+Z direction). When the direction of the magnetic flux lines Mf in the plasma generation space U is the direction from the upstream side to the downstream side of the jetting direction of the thermal spraying powder R1, as shown in ^FIG . Due to the magnetic field B, a force F directed away from the central axis O of the supply unit 10 is applied. As a result, Ar ⁺ moves away from the central axis O. As a result, the shape of the plasma jet P becomes thicker, the cross-sectional distribution on the surface to be thermally sprayed becomes broader, and the in-plane uniformity of the thermal sprayed film is improved.

As described above, the shape of the plasma jet P can be controlled by changing the orientation of the magnetic flux line Mf by interchanging the arrangement of the N and S poles of the permanent magnets M1 and M2.

In the examples of FIGS. 5 to 7, the case where the shape of the plasma jet P is controlled by changing the direction of the magnetic flux line by interchanging the arrangement of the N and S poles of the permanent magnets M1 and M2 has been described. , the disclosure is not limited thereto. For example, the shape of the plasma jet P may be controlled by changing the magnetic forces of the permanent magnets M1 and M2. Also, the shape of the plasma jet P may be controlled by changing the number of permanent magnets, for example. Alternatively, the shape of the plasma jet P may be controlled by using electromagnets instead of the permanent magnets M1 and M2 to change the direction of the magnetic flux lines.

Further, in the examples of FIGS. 5 to 7, a case where a clockwise swirling flow is formed in the spraying direction of the thermal spraying powder R1 has been described, but the present disclosure is not limited to this. For example, a counterclockwise swirl flow (hereinafter referred to as a "left swirl flow") may be formed in the spraying direction of the thermal spray powder R1. In this case, when the direction of the magnetic flux lines Mf in the plasma generation space U is the direction from the downstream side to the upstream side in the injection direction of the thermal spraying powder R1, Ar ⁺ contained in the counterclockwise swirling flow is the central axis of the supply section 10. It receives a force in the direction away from O and moves in the direction away from the central axis O. On the other hand, when the direction of the magnetic flux lines Mf in the plasma generation space U is the direction from the upstream side to the downstream side of the jetting direction of the thermal spraying powder R1, the Ar ⁺ contained in the counterclockwise swirling flow is the central axis O of the supply unit 10. receives a force in the direction of approaching and moves in the direction of approaching the central axis O.

[Magnet arrangement and magnetic field]
8 to 10 are diagrams showing simulation results of magnetic field distribution, showing the distribution of magnetic flux lines on one side with respect to the central axis O of the supply section 10. FIG.

In FIG. 8, three circular rings are arranged around the central axis O of the supply unit 10 in the outer peripheral portion of the plasma generating space U so that the upstream side in the injection direction of the thermal spraying powder R1 is the N pole and the downstream side is the S pole. 4 shows simulation results of the distribution of the magnetic flux lines Mf when the permanent magnets M1 to M3 are arranged. In the example of FIG. 8, the permanent magnets M1, M2, and M3 are arranged at the upper, middle, and lower outer peripheral portions of the plasma generating space U in the height direction, respectively. The upper position is at approximately the same height as the tip of the nozzle 11, the intermediate position is at approximately the middle position in the height direction of the plasma generating space U, and the lower position is approximately at the same height as the lower end of the main body 12. height position.

As shown in FIG. 8, the magnetic flux lines Mf formed by the permanent magnets M1 to M3 extend along the central axis O in the range from the upper position in the height direction of the plasma generating space U to the lower part of the plasma generating space U. direction. As a result, the magnetic field acts in the radial direction of the permanent magnets M1 to M3 on Ar.sup. ⁺ forming a swirl flow in the plasma generation space U, so that Ar.sup ^.+ moves toward or away from the central axis O. FIG. Specifically, for example, when Ar gas introduced into the plasma generation space U forms a right-handed swirling flow in the plasma generation space U, Ar ⁺ moves away from the central axis O. As shown in FIG. Therefore, the shape of the plasma jet P becomes thicker, the cross-sectional distribution on the surface to be thermally sprayed becomes broader, and the in-plane uniformity of the thermal sprayed film is improved. On the other hand, for example, when the Ar gas introduced into the plasma generation space U forms a left-handed swirling flow in the plasma generation space U, Ar ⁺ moves toward the central axis O. As shown in FIG. Therefore, the shape of the plasma jet P is elongated in the Z direction, and the plasma density increases in the vicinity of the central axis O of the supply section 10 through which the thermal spraying powder R1 passes. As a result, the efficiency of heat input to the thermal spray powder R1 is improved, and the efficiency and quality of the thermal spray film are improved.

In FIG. 9, two circular rings are arranged around the central axis O of the supply unit 10 on the outer periphery of the plasma generating space U so that the upstream side in the injection direction of the thermal spraying powder R1 is the N pole and the downstream side is the S pole. 2 shows a simulation result of the distribution of the magnetic flux lines Mf when the permanent magnets M2 and M3 are arranged. In the example of FIG. 9, the permanent magnets M2 and M3 are arranged on the outer periphery of the plasma generating space U at intermediate and lower positions in the height direction, respectively.

As shown in FIG. 9, the magnetic flux line Mf formed by the permanent magnets M2 and M3 extends along the central axis O in the range from the middle position in the height direction of the plasma generation space U to the bottom of the plasma generation space U. direction. As a result, the magnetic field acts in the radial direction of the permanent magnets M2 and M3 on Ar ⁺ forming a swirling flow in the plasma generation space U, so that Ar ⁺ moves toward or away from the central axis O. FIG. Specifically, for example, when Ar gas introduced into the plasma generation space U forms a right-handed swirling flow in the plasma generation space U, Ar ⁺ moves away from the central axis O. As shown in FIG. Therefore, the shape of the plasma jet P becomes thicker, the cross-sectional distribution on the surface to be thermally sprayed becomes broader, and the in-plane uniformity of the thermal sprayed film is improved. On the other hand, for example, when the Ar gas introduced into the plasma generation space U forms a left-handed swirling flow in the plasma generation space U, Ar ⁺ moves toward the central axis O. As shown in FIG. Therefore, the shape of the plasma jet P is elongated in the Z direction, and the plasma density increases in the vicinity of the central axis O of the supply section 10 through which the thermal spraying powder R1 passes. As a result, the efficiency of heat input to the thermal spray powder R1 is improved, and the efficiency and quality of the thermal spray film are improved.

In FIG. 10, two circular rings are arranged around the central axis O of the supply unit 10 on the outer periphery of the plasma generation space U so that the upstream side in the injection direction of the thermal spraying powder R1 is the N pole and the downstream side is the S pole. 2 shows a simulation result of the distribution of magnetic flux lines Mf when permanent magnets M1 and M2 are arranged. In the example of FIG. 10, the permanent magnets M1 and M2 are arranged on the outer periphery of the plasma generating space U at upper and middle positions in the height direction, respectively.

As shown in FIG. 10, the magnetic flux line Mf formed by the permanent magnets M1 and M2 extends along the central axis O in the range from the upper position in the height direction of the plasma generation space U to the middle position of the plasma generation space U. facing forward. As a result, the magnetic field acts in the radial direction of the permanent magnets M2 and M3 on Ar ⁺ forming a swirling flow in the plasma generation space U, so that Ar ⁺ moves toward or away from the central axis O. FIG. Specifically, for example, when Ar gas introduced into the plasma generation space U forms a right-handed swirling flow in the plasma generation space U, Ar ⁺ moves away from the central axis O. As shown in FIG. Therefore, the shape of the plasma jet P becomes thicker, the cross-sectional distribution on the surface to be thermally sprayed becomes broader, and the in-plane uniformity of the thermal sprayed film is improved. On the other hand, for example, when Ar gas introduced into the plasma generation space U forms a left-handed swirling flow in the plasma generation space U, Ar ⁺ moves toward the central axis O. As shown in FIG. Therefore, the shape of the plasma jet P becomes elongated in the Z direction, and the plasma density increases in the vicinity of the central axis O of the supply section 10 through which the thermal spraying powder R1 passes. As a result, the efficiency of heat input to the thermal spray powder R1 is improved, and the efficiency and quality of the thermal spray film are improved.

As described above with reference to FIGS. 8 to 10, the magnetic field distribution in the plasma generation space U is changed by changing the number of permanent magnets and the arrangement of the permanent magnets in the plasma generation space U. FIG. As a result, the force that Ar 2 ⁺ contained in the swirling flow receives from the magnetic field of the permanent magnet changes, and the shape of the plasma jet P changes. For example, by arranging three permanent magnets M1, M2, M3, rather than arranging two permanent magnets M2, M3 or two permanent magnets M1, M2, magnetic flux lines parallel to the central axis O of the supply unit 10 Since the length of Mf becomes longer, a long and stable plasma jet P can be formed.

[Plasma spraying method]
FIG. 11 is a flow chart showing an example of a plasma spraying method by the plasma spraying apparatus 1. As shown in FIG. The processing by the plasma spraying method shown in FIG. 11 is executed by the controller 30 .

When the plasma thermal spraying method shown in FIG. 11 is started, the control unit 30 controls the gas supply source 41 to introduce Ar gas into the supply unit 10 and the plasma generation space U (step S1). As a result, a flow carrying the thermal spraying powder R1 is formed in the flow path 11a, and a swirling flow is formed in the plasma generating space U. As shown in FIG.

Subsequently, the controller 30 controls the DC power supply 50 to apply current to the electrodes of the plasma generator 60 to generate plasma (step S2). Thereby, a plasma jet P of Ar gas is generated in the plasma generating space U. As shown in FIG. Further, the control unit 30 supplies the thermal spraying powder R1 from the feeder 20 to the nozzle 11 (step S3), and performs film formation by thermal spraying (step S4). As a result, the thermal spraying powder R1 is melted by the heat of the plasma jet P and jetted toward the surface of the base material W, forming a coating F1 on the surface of the base material W by thermal spraying. At this time, a magnetic field parallel to the central axis O of the supply unit 10 is applied to the plasma generation space U by the magnetic field generator 80, and the shape of the plasma jet P changes compared to when no magnetic field is applied.

Subsequently, the control unit 30 determines whether or not to end thermal spraying (step S5). When the control unit 30 determines to end the thermal spraying, it ends the process. On the other hand, when the control unit 30 determines not to end the thermal spraying, the process returns to step S4 to continue film formation.

According to the plasma spraying method described above, the magnetic field generator 80 applies a magnetic field parallel to the central axis O of the supply unit 10 to the plasma generation space U while film formation is being performed by thermal spraying. Thereby, the shape of the plasma jet P can be changed. Further, when the magnetic field generating unit 80 includes a movable permanent magnet, the shape of the plasma jet P can be changed during film formation by thermal spraying by changing the position of the permanent magnet during film formation by thermal spraying. . Further, when the magnetic field generator 80 includes an electromagnet, the shape of the plasma jet P can be changed during film formation by thermal spraying by changing the direction of the magnetic field and the magnetic force during the film formation by thermal spraying.

[Plasma jet shape and amount of thermal spray coating]
FIG. 12 is a diagram showing evaluation results of the shape of the plasma jet P and the amount of the thermal sprayed film formed. Observation results of [g/pass] and the shape of the plasma jet P are shown. The film formation amount [g/pass] means the amount of the thermal sprayed film formed per pass when plasma thermal spraying is performed while reciprocating the substrate W in the horizontal direction at a predetermined speed. In FIG. 12, the plasma jets P ejected from the nozzles 11 under the thermal spraying conditions A, B, C, D and E are indicated by plasma jets PA, PB, PC, PD and PE, respectively. Also, the plasma jets PA, PB, PC, PD, and PE are divided into first bright portions PA1, PB1, PC1, PD1, and PE1 having a first brightness, and second bright portions PA2, having a second brightness. PB2, PC2, PD2, and PE2 are shown separately. The second brightness is brightness darker than the first brightness.

The thermal spraying condition A is a condition in which no magnetic field is applied to the plasma generation space U. FIG.

The thermal spraying condition B is such that the permanent magnets M1 and M2 are arranged at upper and intermediate positions in the height direction of the plasma generating space U so that the upstream side of the spraying direction of the thermal spraying powder R1 becomes the S pole and the downstream side becomes the N pole. , are the conditions for applying a magnetic field to the plasma generating space U. Under the thermal spraying condition B, in the plasma generation space U, a magnetic field is applied in a direction opposite to the jetting direction of the thermal spraying powder R1.

The thermal spraying condition C is such that the permanent magnets M2 and M3 are arranged at the middle position and the lower position in the height direction of the plasma generating space U so that the upstream side of the spraying direction of the thermal spraying powder R1 becomes the S pole and the downstream side becomes the N pole. , are the conditions for applying a magnetic field to the plasma generating space U. Under the thermal spraying condition C, in the plasma generation space U, a magnetic field is applied in the direction opposite to the jetting direction of the thermal spraying powder R1.

The thermal spraying condition D is such that the permanent magnets M1, M2, and M2 are arranged at the upper, middle, and lower positions in the height direction of the plasma generation space U so that the upstream side of the spraying direction of the thermal spraying powder R1 has an S pole and the downstream side has an N pole. These are the conditions under which each M3 is arranged and a magnetic field is applied to the plasma generation space U. FIG. Under the thermal spraying condition D, a magnetic field is applied in the direction opposite to the jetting direction of the thermal spraying powder R1.

The thermal spraying condition E is such that the permanent magnets M1, M2, and M2 are arranged at upper, middle, and lower positions in the height direction of the plasma generating space U so that the upstream side of the spraying direction of the thermal spraying powder R1 has an N pole and the downstream side has an S pole. These are the conditions under which each M3 is arranged and a magnetic field is applied to the plasma generation space U. FIG. Under the thermal spraying condition E, a magnetic field is applied in the plasma generation space U in the same direction as the spraying direction of the thermal spraying powder R1.

Under the thermal spraying conditions A to E, the Ar gas was supplied to the plasma generating space U to form a right-handed swirling flow in the plasma generating space U in the direction in which the thermal spraying powder R1 was injected.

As shown in FIG. 12, the lengths LB1, LC1, and LD1 of the first bright portions PB1, PC1, and PD1 under the thermal spraying conditions B, C, and D are longer than the length LA1 of the first bright portion PA1 under the thermal spraying conditions A. I know it's getting longer. On the other hand, it can be seen that the length LE1 of the first bright portion PE1 under the thermal spraying condition E is substantially the same as the length LA1 of the first bright portion PA1 under the thermal spraying condition A. Further, the lengths LB2, LC2, and LD2 of the second bright portions PB2, PC2, and PD2 under the thermal spray conditions B, C, and D are longer than the length LA2 of the second bright portions PA2 under the thermal spray conditions A. I understand. On the other hand, it can be seen that the length LE2 of the second bright portion PE2 under the thermal spraying condition E is substantially the same as the length LA2 of the second bright portion PA2 under the thermal spraying condition A. From these results, it can be said that by performing plasma spraying under thermal spraying conditions B, C, and D, plasma jets PB, PC, and PD having elongated shapes can be formed compared to performing plasma spraying under thermal spraying condition A. That is, it can be said that by forming a right-handed spiral flow in the plasma generation space U and applying a magnetic field in a direction opposite to the spraying direction of the thermal spraying powder R1, the plasma jet P can be formed in an elongated shape.

In particular, the length LD1 of the first bright portion PD1 and the length LD2 of the second bright portion PD2 under the thermal spraying conditions D correspond to the lengths LB1, LC1 of the first bright portions PB1 and PC1 under the thermal spraying conditions B and C and the lengths LB1 and LC1 of the second bright portion PD2. The lengths of parts PB2 and PC2 are longer than LB2 and LC2. From this result, it can be said that the plasma spraying under the thermal spraying condition D can form a plasma jet PD having a longer and narrower shape than the plasma spraying under the thermal spraying conditions B and C. That is, by forming a right-handed swirling flow in the plasma generation space U and applying a magnetic field in the opposite direction to the injection direction of the thermal spray powder R1 in the range from the upper position to the lower position of the plasma generation space U, the plasma generation space U is elongated. It can be said that an elongated plasma jet P can be formed.

Further, as shown in FIG. 12, under the thermal spraying condition D, the amount of the thermal sprayed film was 0.0063 g/pass. On the other hand, under the thermal spraying condition A, the amount of the thermal sprayed film is 0.0035 g/pass, under the thermal spraying conditions B and C, the amount of the thermal sprayed film is 0.0036 g/pass, and under the thermal spraying condition E, the thermal sprayed film is was 0.0039 g/pass. From these results, by forming a right-handed swirling flow in the plasma generating space U and applying a magnetic field in the opposite direction to the injection direction of the thermal spray powder R1 in the range from the upper position to the lower position of the plasma generating space U, , it can be said that the amount of the thermal sprayed film formed per pass can be increased. That is, it can be said that the film forming efficiency of the thermal sprayed film can be improved.

[Anode-cathode voltage]
FIG. 13 is a graph showing the evaluation results of the anode-cathode voltage, and shows the anode-cathode voltage when plasma spraying was performed under the spraying conditions A, D, and E described above. In FIG. 13, the horizontal axis indicates time [min], and the vertical axis indicates the anode-cathode voltage [V].

As shown in FIG. 13, the anode-cathode voltage under thermal spraying condition D is higher than the anode-cathode voltage under thermal spraying condition A. As shown in FIG. From this result, by forming a right-handed swirling flow in the plasma generating space U and applying a magnetic field in the direction opposite to the injection direction of the thermal spray powder R1 in the range from the upper position to the lower position of the plasma generating space U, It is considered that the amount of heat input to the thermal spray powder R1 increases. On the other hand, the anode-cathode voltage under the thermal spraying condition E is lower than the anode-cathode voltage under the thermal spraying condition A. From this result, when a right-handed swirling flow is formed in the plasma generating space U and a magnetic field is applied in the same direction as the spraying direction of the thermal spraying powder R1 in the range from the upper position to the lower position of the plasma generating space U, the thermal spraying powder R1 It is thought that the heat input to the

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The above-described embodiments may be omitted, substituted or modified in various ways without departing from the scope and spirit of the appended claims.

For example, according to the plasma spraying apparatus 1 of one embodiment, cleaning for removing a film deposited on the anode can be performed. Specifically, during plasma spraying, the value and direction of the current flowing through the coil of the electromagnet are adjusted to control the direction and magnetic force of the magnetic field, and the Ar ^{2 +} contained in the plasma is moved away from the central axis O. Thus, it may collide with the projecting portion 12d functioning as an anode. As a result, the film deposited on the projecting portion 12d functioning as an anode can be removed (cleaned) by the sputtering effect of Ar ^{2 +} that collides with the projecting portion 12d functioning as an anode. Further, the removal of the film may be performed without supplying the thermal spraying powder R1 to the nozzle 11 .

1 Plasma spraying device 10 Supply unit 11 Nozzle 11b Opening 40 Gas supply unit 41 Gas supply source 43 Pipe 60 Plasma generation unit 80 Magnetic field generation units 81a, 81b, 81c Permanent magnets 82a, 82b, 82c Permanent magnets 83a, 83b, 83c Electromagnet M1 ~M3 Permanent magnet O Central axis R1 Thermal spraying powder U Plasma generation space

Claims (19)

a supply unit that carries the powder of the thermal spraying material with the first gas and injects it from the opening at the tip;
a plasma generator that uses the injected first gas to generate plasma having an axis common to that of the supply section;
a gas flow path for supplying a second gas forming a swirling flow with a central axis of the supply unit as a swirling axis in the plasma generation space;
a magnetic field generator that generates a magnetic field parallel to the central axis of the supply unit in the plasma generation space;
A plasma spray apparatus comprising: The magnetic field generator has an annular permanent magnet centered on the central axis,
2. The plasma spray apparatus of claim 1 . A plurality of the permanent magnets are arranged at intervals in the direction of the central axis,
3. The plasma spray apparatus of claim 2 . The permanent magnet is movable in the direction of the central axis,
4. A plasma spraying apparatus according to claim 2 or 3 . The magnetic field generator has an electromagnet including a coil centered on the central axis,
5. A plasma spraying apparatus according to any one of claims 1-4 . the gas flow path forms a clockwise swirling flow in the direction of ejection of the powder;
The magnetic field generating unit generates a magnetic field in a direction opposite to the injection direction of the powder,
6. A plasma spraying apparatus according to any one of claims 1-5 . the gas flow path forms a counterclockwise swirling flow in the powder injection direction,
The magnetic field generator generates a magnetic field in the same direction as the direction of ejection of the powder,
6. A plasma spraying apparatus according to any one of claims 1-5 . The supply unit sprays thermal spray powder with a particle size of 1 μm to 10 μm,
8. A plasma spraying apparatus according to any one of claims 1-7 . a supply unit that carries the powder of the thermal spraying material with the first gas and injects it from the opening at the tip;
a plasma generator that uses the injected first gas to generate plasma having an axis common to that of the supply section;
a gas flow path for supplying a second gas forming a swirling flow with a central axis of the supply unit as a swirling axis in the plasma generation space;
a magnetic field generator having an annular permanent magnet centered on the central axis of the supply unit;
with
The magnetic field generator generates a magnetic field parallel to the central axis,
Plasma spray equipment. A plurality of the permanent magnets are arranged at intervals in the direction of the central axis,
10. The plasma spray apparatus of Claim 9 . The permanent magnet is movable in the direction of the central axis,
11. A plasma spraying apparatus according to claim 9 or 10 . the gas flow path forms a clockwise swirling flow in the direction of ejection of the powder;
The magnetic field generating unit generates a magnetic field in a direction opposite to the injection direction of the powder,
12. Plasma spraying apparatus according to any one of claims 9-11 . the gas flow path forms a counterclockwise swirling flow in the powder injection direction,
The magnetic field generator generates a magnetic field in the same direction as the direction of ejection of the powder,
12. Plasma spraying apparatus according to any one of claims 9-11 . The supply unit sprays thermal spray powder with a particle size of 1 μm to 10 μm,
14. A plasma spraying apparatus according to any one of claims 9-13 . a supply unit that carries the powder of the thermal spraying material with the first gas and injects it from the opening at the tip;
a plasma generator that uses the injected first gas to generate plasma having an axis common to that of the supply section;
a gas flow path for supplying a second gas forming a swirling flow with a central axis of the supply unit as a swirling axis in the plasma generation space;
a magnetic field generator having an electromagnet including a coil centered on the central axis of the supply unit;
with
The magnetic field generator generates a magnetic field parallel to the central axis,
Plasma spray equipment. the gas flow path forms a clockwise swirling flow in the direction of ejection of the powder;
The magnetic field generating unit generates a magnetic field in a direction opposite to the injection direction of the powder,
16. The plasma spray apparatus of Claim 15 . the gas flow path forms a counterclockwise swirling flow in the powder injection direction,
The magnetic field generator generates a magnetic field in the same direction as the direction of ejection of the powder,
16. The plasma spray apparatus of Claim 15 . The supply unit sprays thermal spray powder with a particle size of 1 μm to 10 μm,
18. The plasma spray apparatus of any one of claims 15-17 . a step of carrying the powder of the thermal spraying material by the first gas in the supply section and injecting it from the opening at the tip of the supply section;
generating a plasma having a common axis with the supply unit using the injected first gas;
a step of supplying a second gas forming a swirling flow with the center axis of the supply unit as a swirl axis to the plasma generation space;
generating a magnetic field parallel to the central axis of the supply unit in the plasma generation space;
A method of plasma spraying, comprising:

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