Plasma spraying device

Abstract

The present application relates to a plasma spraying device. A technique capable of suppressing powder from adhering to a nozzle and improving productivity is provided. The plasma spraying device includes a nozzle body having a passage extending in a straight line shape through which a gas and a powder can flow, and a first electrode provided at a front end of the nozzle body in a detachable manner, having a spray outlet communicating with the passage and capable of spraying the gas and the powder, the first electrode having an axis common to a central axis of the nozzle body. Further, the plasma spraying device includes a second electrode provided at an outer side of the first electrode and having an axis common to the central axis of the nozzle body. The plasma spraying device generates plasma of the gas between the first electrode and the second electrode, melts the powder sprayed from the spray outlet by the plasma, and forms a sprayed film by blowing the melted powder toward a substrate. Further, an inner diameter of the spray outlet is larger than an inner diameter of the passage.

Description

Technical Field

[0001] This disclosure relates to a plasma spraying apparatus. Background Technology

[0002] Patent Document 1 discloses a plasma spraying apparatus that sprays high-speed gas and powder from the nozzle outlet while using the heat of the plasma to melt the sprayed powder and form a molten powder coating on the surface of a substrate.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-78054 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This disclosure provides a technique that can suppress powder adhesion to nozzles and improve productivity.

[0008] Solution for solving the problem

[0009] According to a technical solution of this disclosure, a plasma spraying apparatus is provided, wherein the plasma spraying apparatus includes: a cylindrical nozzle body; a cylindrical first electrode, which is detachably disposed at the front end of the nozzle body and has an axis common to the central axis of the nozzle body; and a second electrode, which is disposed outside the first electrode and has an axis common to the central axis of the nozzle body. The nozzle body and the first electrode have a continuous passage for gas and powder to flow through. The first electrode has an outlet communicating with the passage and capable of ejecting the gas and the powder. The inner diameter of the outlet is larger than the inner diameter of the passage. The plasma spraying apparatus is configured to generate plasma of the gas between the first electrode and the second electrode, and to use the plasma to melt the powder ejected from the outlet.

[0010] The effects of the invention

[0011] According to a technical solution, it is possible to suppress powder adhesion to the nozzle and thus improve productivity. Attached Figure Description

[0012] Figure 1 This is a diagram showing an example of the overall structure of the plasma spraying apparatus according to the embodiment.

[0013] Figure 2 It is an enlarged representation Figure 1 A side sectional view of the electrode structure.

[0014] Figure 3 It means Figure 1 An explanatory diagram of the area around the nozzle.

[0015] Figure 4 This is an explanatory diagram illustrating the nozzle used in an evaluation experiment of plasma spraying.

[0016] Figure 5 This is a graph showing the changes in feeder pressure during the evaluation experiment of plasma spraying.

[0017] Figure 6 (a) is a longitudinal sectional view of the ejection cylinder of the first modified example. Figure 6 (b) is a longitudinal sectional view of the ejection cylinder of the second modified example. Detailed Implementation

[0018] The embodiments for implementing this disclosure will now be described with reference to the accompanying drawings. In the drawings, the same reference numerals are sometimes used to denote the same constituent parts, and repeated descriptions are omitted.

[0019] Figure 1 This is a diagram illustrating an example of the overall structure of the plasma spraying apparatus 1 according to the embodiment. (See diagram below.) Figure 1 As shown, the plasma spraying apparatus 1 is an apparatus in which powder of the spraying material (hereinafter referred to as "spraying powder R1") is sprayed toward the surface of the substrate W while being melted by plasma, thereby forming a sprayed film F1 on the surface of the substrate W.

[0020] The plasma spraying apparatus 1 includes: a spraying section 10 for spraying spraying powder R1; a gas supply section 40 for supplying gas to the spraying section 10; a cooling section 60 for cooling the spraying section 10; and a control section 70 for controlling the operation of each structure.

[0021] The ejection section 10 includes a cylindrical nozzle 11 and a feeder 20 that supplies plating powder R1 into the nozzle 11. Furthermore, the front end of the ejection section 10 is disposed within the housing section 30 of the plasma plating apparatus 1.

[0022] The particle size of the sprayed plating powder R1 from the ejection section 10 is, for example, 1 μm to 10 μm. Examples of spraying powder R1 include micro powders of metals such as copper (Cu), lithium (Li), iron (Fe), aluminum (Al), nickel (Ni), and molybdenum (Mo). Alternatively, the spraying powder R1 can also be a micro powder of resins such as polyester. Furthermore, the spraying powder R1 can also be alumina, yttrium oxide, yttrium fluoride, zirconium oxide, or mullite (Al6O3). 13 Micro powders of ceramics such as Si2, spinel (MgAl2O4) or composites of these ceramics.

[0023] The nozzle 11 has a nozzle body 12 extending in a straight line and an ejection cylinder 15 disposed at the front end of the nozzle body 12. The axial length of the ejection cylinder 15 is shorter than the axial length of the nozzle body 12. The nozzle 11 makes the nozzle body 12 and the ejection cylinder 15 independent components, so that only the ejection cylinder 15 can be replaced during device maintenance, etc.

[0024] The nozzle 11 has a passage 11a on its inner side for the flow of powder for spraying. In a cross-sectional view orthogonal to the axial direction of the nozzle 11, the passage 11a is formed into a perfect circle and extends from the base end of the nozzle body 12 to the front end of the ejection cylinder 15. That is, the nozzle body 12 has a main body hole 12a constituting the passage 11a at its axial center, and on the other hand, the ejection cylinder 15 has an ejection hole 15a constituting the passage 11a at its axial center.

[0025] The nozzle body 12 is formed into a cylindrical shape from a conductive or non-conductive metallic material. The nozzle body 12 has a main body hole 12a along its central axis. The main body hole 12a extends linearly along the axial direction of the nozzle body 12 with a constant inner diameter. A connecting port 12b is formed at the front end of the nozzle body 12 (the end on the side of the ejection cylinder 15), communicating with both the main body hole 12a and the ejection hole 15a.

[0026] The ejection cylinder 15 is made of a conductive metal material and is cylindrical, slightly thinner than the nozzle body 12. An ejection orifice 15a extends linearly through the axis of the ejection cylinder 15. Therefore, the ejection cylinder 15 has: an ejection outlet 15b, which communicates with the ejection orifice 15a at its front end; and a base opening 15c (see reference). Figure 2 The nozzle 15 communicates with the ejection orifice 15a at its base end. Furthermore, the ejection cylinder 15 has a flange 16 on its outer peripheral surface at the base end. The flange 16 engages with an inner protrusion 31 provided within the housing portion 30 in a detachable manner.

[0027] The housing portion 30 is formed of a non-conductive resin material. The housing portion 30 fixes the ejection cylinder 15 in such a way that the central axis of the nozzle body 12 and the central axis of the ejection cylinder 15 share a common axis. By fixing the nozzle 11 to the housing portion 30, the axis of the passage 11a is made to extend in a straight line along the vertical direction (up and down direction) of the plasma spraying apparatus 1. In addition, the fixing of the ejection cylinder 15 is not limited to the engagement between the flange 16 and the inner protrusion 31; the ejection cylinder 15 can be fixed to the housing portion 30 or the nozzle body 12 by using an appropriate engagement method (threaded connection, welding, bonding, etc.).

[0028] With the nozzle 11 fixed, the housing portion 30 is in close contact with the outer peripheral surface of the nozzle body 12 from its axial center position to its front end side. Furthermore, the housing portion 30 is in close contact with the outer peripheral surface of the base end side of the ejection cylinder 15. The housing portion 30 has a generation space 30a around the front end side (lower end side) of the ejection cylinder 15 for generating a plasma jet P. Moreover, the base end side (upper end side) of the nozzle body 12 protrudes from the upper surface of the housing portion 30.

[0029] The feeder 20 is connected to the base end of the nozzle 11 (nozzle body 12) and supplies the plating powder R1 to the nozzle 11. The feeder 20 includes: a container 21 that holds the plating powder R1; and an actuator 22 disposed in the container 21. The container 21 is, for example, formed in a bowl shape, and the plating powder R1 is fed from the container 21 into the passage 11a by applying vibration in the rotational direction from the actuator 22. The actuator 22 uses a motor and a transmission mechanism (not shown) that transmits the rotational drive of the motor.

[0030] The gas supply unit 40 of the plasma spraying apparatus 1 supplies plasma generating gas as the first gas to the nozzle 11. The plasma generating gas is the gas used to generate plasma and also functions as a carrier gas for transporting the spraying powder R1 in the passage 11a of the nozzle 11. For example, argon (Ar), nitrogen (N2), helium (He), or a mixture thereof can be used as the plasma generating gas. Hereinafter, the case of using Ar gas as the plasma generating gas will be described as an example.

[0031] The gas supply unit 40 has a supply pipe 41 for supplying Ar gas (plasma generating gas). Furthermore, the gas supply unit 40 includes a gas supply source 42, a valve 43, and a mass flow controller (MFC) 44, sequentially arranged upstream and downstream of the gas flow direction in the supply pipe 41. The gas supply unit 40 supplies Ar gas from the gas supply source 42 based on the opening of the valve 43, and the flow rate is controlled by the mass flow controller 44, thereby supplying a predetermined flow rate of Ar gas to the passage 11a of the nozzle 11.

[0032] Furthermore, the gas supply unit 40 supplies Ar gas, used for vortex generation, as a second gas to the generation space 30a of the housing 30. The gas supply unit 40 has a branch pipe 45 branching from the supply pipe 41, and a mass flow controller (MFC) 46 is provided in the branch pipe 45. That is, when the gas supply unit 40 supplies Ar gas from the gas supply source 42 based on the opening of the valve 43, the mass flow controller 46 controls the flow rate, thereby allowing a predetermined flow rate of Ar gas to pass through the branch pipe 45.

[0033] The distribution pipe 45 is connected to the gas flow path 32 located within the housing 30. The gas flow path 32 extends longitudinally from the upper part to the lower part of the housing 30 and bends laterally at a midway point, thereby communicating with the generation space 30a. Ar gas supplied by the gas supply unit 40 flows laterally into the generation space 30a, thereby forming a vortex around the ejection cylinder 15 within the generation space 30a.

[0034] In addition, Figure 1 The diagram only shows a supply path for Ar gas introduced laterally into the generation space 30a, but multiple openings communicating with the gas flow path 32 can also be provided in the housing 30 along the circumference of the generation space 30a in the direction of the generation space 30a.

[0035] The plasma plating apparatus 1 has a DC power supply 51 outside the housing 30. By supplying DC power to the cathode electrode 52 (first electrode) and anode electrode 53 (second electrode) provided in the housing 30, plasma is generated in the generation space 30a. In this embodiment, the plasma plating apparatus 1 uses a nozzle 11 (ejection cylinder 15) made of metal as the cathode electrode 52. Furthermore, the housing 30 has a metal block 35 on the inner peripheral surface of the generation space 30a, which functions as the anode electrode 53.

[0036] Specifically, the housing portion 30 has a recess 33 and a bulge 34 as portions forming the inner peripheral surface of the generation space 30a. The recess 33 is provided with an opening for the aforementioned gas flow path 32.

[0037] The bulge 34 is formed of a metal block 35, which protrudes radially inward from the recess 33. The metal block 35 is formed of a conductive metal material. The metal block 35 is formed in an annular shape, and its outer periphery is joined to the housing portion 30. The portion enclosed by the metal block 35 becomes a jet passage 35a through which the generated plasma jet P passes. The central axis of the metal block 35 (jet passage 35a), which serves as the second electrode, shares the same axis as the central axis of the nozzle body 12 (nozzle 11). Furthermore, the metal block 35 is formed in cross-section as a concave shape with an open outer periphery, allowing cooling media such as water to flow through the concave space 35b.

[0038] The plasma spraying apparatus 1, which has the above structure, supplies direct current from a direct current power supply 51 to the nozzle 11 (cathode electrode 52) and the metal block 35 (anode electrode 53). As a result, a discharge can occur between the cathode electrode 52 and the anode electrode 53, promoting the ionization of Ar gas and generating plasma in the generation space 30a.

[0039] The cooling section 60 includes: a cooling unit 61; a cooling medium outlet pipe 62 for supplying cooling medium to flow out of the cooling unit 61; and a cooling medium inlet pipe 63 for supplying cooling medium to return to the cooling unit 61. Furthermore, the cooling section 60 includes a valve 64 and a flow meter (FM) 65 in the cooling medium outlet pipe 62, and a valve 66 in the cooling medium inlet pipe 63.

[0040] The cooling medium outlet pipe 62 and the cooling medium inlet pipe 63 are connected to the cooling medium flow path 67 formed within the housing portion 30. The cooling medium flow path 67 communicates with the nozzle cooling space 67a surrounding the outer side of the nozzle body 12 and the recessed space 35b of the metal block 35. The cooling medium supplied from the cooling unit 61 to the cooling medium outlet pipe 62 flows into the cooling medium flow path 67 of the housing portion 30, passes through the nozzle cooling space 67a and the recessed space 35b within the housing portion 30, and flows out into the cooling medium inlet pipe 63, thereby returning to the cooling unit 61. Thus, the cooling unit 60 can adjust the temperature of the housing portion 30 during plasma generation.

[0041] Furthermore, the plasma spraying apparatus 1 may also include a magnetic field generating unit (not shown) that generates a magnetic field in the generation space 30a. The magnetic field generating unit may be configured, for example, by placing a ring-shaped permanent magnet or electromagnet at the same height as the metal block 35.

[0042] The control unit 70 of the plasma spraying apparatus 1 is a control computer having one or more processors, memory, input / output interfaces, and electronic circuits. The one or more processors are composed of one or more of the following: CPU, ASIC, FPGA, circuits made of multiple discrete semiconductors, etc. The memory includes volatile memory and non-volatile memory (computer storage media, floppy disks, optical disks, hard disks, optical discs, memory cards, etc.), with programs stored in the non-volatile memory.

[0043] The control unit 70 controls each structure of the plasma plating apparatus 1 to perform plasma plating by executing a program in the memory through a processor. At a position separated from the housing 30, a plating film F1 is formed on the surface of the substrate W, which is positioned opposite the jet passage 35a. Furthermore, the plasma plating apparatus 1 can perform plating while moving the substrate W or while moving the nozzle 11. When plating while moving the substrate W, for example, plating is performed while moving the stage (not shown) holding the substrate W in the horizontal direction. When plating while moving the nozzle 11, for example, the housing 30 is fixed in a horizontally movable arm, and plating is performed while moving the housing 30 horizontally using the arm.

[0044] Furthermore, in the plasma spraying apparatus 1 of this embodiment, the electrode structure 80, which includes a nozzle 11 (ejection cylinder 15) serving as a cathode electrode 52 and a metal block 35 serving as an anode electrode 53, can suppress the adhesion of molten spraying powder R1 to the inner wall of the ejection cylinder 15 during plasma spraying. The structure of this electrode structure 80 will be described below.

[0045] Figure 2 It is an enlarged representation Figure 1 A side sectional view of the electrode structure at 80°. (See figure) Figure 2 As shown, the ejection cylinder 15, which is one of the electrode structures 80, is in the following state: its axial base end side is embedded in the housing portion 30, while its portion from the axial middle to the front end is exposed to the generation space 30a.

[0046] The axial length L (total length) of the ejection cylinder 15 can be set to a range of 7 mm to 15 mm, and in this embodiment it is 10 mm. Furthermore, the axial length of the portion of the ejection cylinder 15 exposed to the generation space 30a (the area from the end face of the housing portion 30 to the front end of the ejection cylinder 15) can be set to a ratio of 1 / 2 to 4 / 5 relative to the axial length L of the ejection cylinder 15.

[0047] The outer peripheral surface 17 of the ejection cylinder 15 has the aforementioned flange 16 at its base end. Furthermore, the outer peripheral surface 17 includes: a body outer peripheral surface 171, which has an outer diameter (diameter) smaller than that of the flange 16 at a position closer to the front end (lower part) than the flange 16; and a front end outer peripheral surface 172, which is connected to the front end of the body outer peripheral surface 171 and whose outer diameter gradually decreases in the front end direction.

[0048] The outer peripheral surface 171 of the torso extends along the axial direction of the ejection cylinder 15 with a constant outer diameter (parallel to the axial direction and in a straight line when viewed in section). The outer diameter of the outer peripheral surface 171 of the torso also depends on the size of the ejection cylinder 15, and for example, it can be set to a range of 4 mm to 8 mm, and in this embodiment it is 6 mm.

[0049] The outer peripheral surface 171 of the torso constitutes most of the outer peripheral surface 17 of the ejection cylinder 15. The axial length of the outer peripheral surface 171 of the torso can be set to a ratio of 2 / 3 to 9 / 10 relative to the axial length L of the ejection cylinder 15.

[0050] The outer peripheral surface 172 of the front end has a conical shape with a diameter that decreases towards the front end, thus making the front end of the ejection cylinder 15 tapered. Due to this outer peripheral surface 172, the outer diameter of the front end of the ejection cylinder 15 is smaller than the outer diameter of the outer peripheral surface 171 of the body. For example, the outer diameter of the front end of the ejection cylinder 15 can be set to a ratio of 1 / 2 to 5 / 6 relative to the outer diameter of the outer peripheral surface 171 of the body. The outer diameter of the front end of the ejection cylinder 15 can be in the range of 3 mm to 5 mm, and in this embodiment, it is 4 mm.

[0051] Furthermore, the shape (including dimensions) of the front peripheral surface 172 can be appropriately designed based on the smooth flow of the Ar gas vortex formed in the generation space 30a and the stability of the plasma discharge. The peripheral surface 172 may also not have a conical shape; for example, it may have a structure with rounded corners between it and the front end of the ejection cylinder 15.

[0052] On the other hand, the diameter (inner diameter φia) of the base opening 15c of the ejection cylinder 15 is set to be the same as the diameter (inner diameter of the main body hole 12a) of the connection port 12b of the nozzle body 12. The ejection cylinder 15 is mounted on the housing 30 with the base opening 15c and the connection port 12b aligned.

[0053] The ejection cylinder 15 has an inner circumferential surface 18 forming the ejection orifice 15a on its inner side. The inner circumferential surface 18 includes: a base end inner circumferential surface 181, whose inner diameter gradually decreases from the base end opening 15c toward the front end; a body inner circumferential surface 182 (first inner circumferential surface), which is connected to the base end inner circumferential surface 181 and has a constant inner diameter in the axial direction; and a front end inner circumferential surface 183 (second inner circumferential surface), which is connected to the body inner circumferential surface 182 and whose inner diameter increases (gradually increases) toward the front end. That is, the passage 11a provided in the nozzle 11 may also be a structure in which the inner circumferential surface constituting the passage 11a expands or contracts in the vertical direction. Even in this case, the axis of the passage 11a extends in a straight line.

[0054] The inner circumferential surface 181 of the base end forms a base end opening 15c at the base end. The inner circumferential surface 181 of the base end is tapered in shape with its diameter decreasing towards the front end, thereby causing the ejection orifice 15a to gradually taper. The axial length of the inner circumferential surface 181 of the base end is longer than the axial length (thickness) of the flange 16.

[0055] The inner circumferential surface 182 of the body portion has a base end connected to the front end of the inner circumferential surface 181 of the base end, and extends axially from this base end with a constant inner diameter φib. The inner diameter φib of the inner circumferential surface 182 of the body portion is smaller than the inner diameter of the main body hole portion 12a of the nozzle body 12 (= the inner diameter φia of the base end opening 15c). The inner diameter φib of the inner circumferential surface 182 of the body portion forms the portion with the smallest diameter in the straight-extending passage 11a. That is, the ejection cylinder 15 can utilize the inner circumferential surface 181 of the base end and the inner circumferential surface 182 of the body portion to accelerate the flow rate of the spraying powder R1 and Ar gas. For example, the inner diameter φib of the inner circumferential surface 182 of the body portion can be set to a ratio of 2 / 3 to 9 / 10 of the inner diameter of the main body hole portion 12a. As for the size of the inner diameter φib of the inner circumferential surface 182 of the body portion, it can be, for example, in the range of 2 mm to 4 mm, and in this embodiment it is 3 mm.

[0056] The axial length of the inner circumferential surface 182 of the torso is longer than the axial length of the inner circumferential surface 181 at the base and the axial length of the inner circumferential surface 183 at the front. The axial length of the inner circumferential surface 182 of the torso can be set to a ratio of 1 / 2 to 4 / 5 relative to the axial length L of the ejection cylinder 15. The axial position of the base of the inner circumferential surface 182 of the torso and the axial position of the base of the outer circumferential surface 171 of the torso (the junction with the flange 16) can be different or the same.

[0057] The front inner circumferential surface 183 has a base end connected to the front end (one end on the nozzle 15b side) of the inner circumferential surface 182 of the body, and is tapered in shape with a diameter that increases from the base end toward the front end, thereby widening the nozzle orifice 15a. Furthermore, the nozzle 11 has a nozzle 15b formed at the very front edge of the nozzle body 15 (hereinafter, the edge forming the nozzle 15b will be referred to as the nozzle forming edge 183f). That is, the nozzle 11 has a nozzle 15b at the very front end of the nozzle body 15, and the passage 11a (body orifice 12a, nozzle orifice 15a) communicates with this nozzle 15b.

[0058] The inner diameter φic of the nozzle outlet forming edge 183f (nozzle outlet 15b) is larger than the inner diameter φib of the inner circumferential surface 182 of the body portion constituting the passage 11a. Therefore, the nozzle outlet 15b of the nozzle 11 is enlarged relative to the inner side and nearby inner circumferential surface 182 of the body portion. Consequently, the wall thickness near the nozzle outlet forming edge 183f is thinner. For example, the inner diameter φic of the nozzle outlet 15b can be set to 1.1 to 1.5 times the inner diameter φib. Furthermore, the inner diameter φic of the nozzle outlet 15b is set to be greater than or equal to the inner diameter φia of the main body hole portion 12a of the nozzle body 12. The size of the inner diameter φic of the nozzle outlet 15b can, for example, be in the range of 2.2 mm to 5 mm, and in this embodiment, it is 3.6 mm. As described above, the outer diameter of the front end of the ejection cylinder 15 is 4 mm; therefore, the front end of the ejection cylinder 15 has an annular end face with a width of 0.2 mm.

[0059] The axial length of the inner circumferential surface 183 at the front end is not particularly limited. For example, it can be set to a ratio of 1 / 10 to 1 / 2 relative to the axial length L of the ejection cylinder 15. That is, the base position of the inner circumferential surface 183 at the front end is set to the range from the axial middle position to the front end of the ejection cylinder 15, thereby suppressing changes in the flow of Ar gas caused by an excessively long inner circumferential surface 183 at the front end. Furthermore, the base position of the inner circumferential surface 183 at the front end is separated from the nozzle 15b by more than 1 / 10 of the axial length L of the ejection cylinder 15, thereby ensuring that the front end sidewall portion 19a of the ejection cylinder 15 is a thin-walled range. In addition, the axial position of the base of the inner circumferential surface 183 at the front end and the axial position of the base of the outer circumferential surface 172 at the front end can be different or the same.

[0060] The tilt angle θ (cone angle) of the front inner circumferential surface 183 relative to the extension direction of the body inner circumferential surface 182 also depends on the axial length of the front inner circumferential surface 183 and the inner diameter φic of the nozzle 15b, for example, it is set to a range of 1° to 45°.

[0061] The front end of the ejection cylinder 15 has an ejection outlet 15b with an inner diameter φic larger than the inner diameter φib, thereby widening the ejection orifice 15a radially outward and suppressing the adhesion of the sprayed powder R1 to the inner circumferential surface 183 of the front end. Furthermore, due to the larger inner diameter φic of the ejection outlet 15b, the wall thickness of the front end sidewall portion 19a between the outer circumferential surface 172 and the inner circumferential surface 183 of the front end of the ejection cylinder 15 is significantly thinner than the wall thickness of the body sidewall portion 19b between the outer circumferential surface 171 and the inner circumferential surface 182 of the body. Therefore, the front end of the ejection cylinder 15 easily heats up under the influence of plasma heat.

[0062] Furthermore, the outer peripheral portion of the metal block 35, which is one of the electrode structures 80, is fixed to the housing portion 30, thereby arranging the jet passage 35a in the generation space 30a as described above. The base end side of the inner peripheral surface 36 of the jet passage 35 of the metal block 35 is formed as a conical surface 361 whose inner diameter decreases (gradually decreases) along the front end direction (the ejection direction of the plasma jet P). In addition, the base end of the conical surface 361 is formed with a rounded corner 362 and is connected to the base end surface 37 of the metal block 35.

[0063] The electrode configuration 80 arranges the ejector cylinder 15 and the metal block 35 close to each other, thereby generating a discharge in the gap 80a between them. Specifically, the front end (ejector outlet 15b) of the ejector cylinder 15 is located further forward than the base end face 37 of the metal block 35, thus entering the jet passage 35a inside the metal block 35. In other words, in cross-sectional view along the axial direction of the electrode configuration 80, the ejector outlet 15b of the cathode electrode 52 and the anode electrode 53 overlap (coincide). In particular, the entire outer peripheral surface 172 and inner peripheral surface 183 of the front end of the ejector cylinder 15 in this embodiment are located further forward than the base end face 37 of the metal block 35. As a result, Ar gas plasma can be generated by the discharge between the front end of the ejector cylinder 15 and the base end of the metal block 35. Alternatively, the electrode structure 80 may be configured with the front end of the ejection cylinder 15 at a position closer to the base end face 37 of the metal block 35 (or it may be configured so that the cathode electrode 52 does not overlap with the anode electrode 53).

[0064] The gap 80a between the ejection cylinder 15 and the metal block 35 forms a space for plasma generation within the electrode structure 80. The interval D of the gap 80a (the minimum distance between the outer peripheral surface 172 of the front end and the inner peripheral surface 36 of the passage) also depends on the shape of the electrode structure 80, and for example, it can be set to a range of 1.0 mm to 3.0 mm, which is 1.02 mm in this embodiment. If the interval D is less than 1.0 mm, there is a possibility that the metal block 35 may be scratched, leading to plasma instability. Furthermore, if the interval D exceeds 3.0 mm, there is a possibility that the plasma discharge position may be unstable.

[0065] The plasma spraying apparatus 1 of this embodiment is basically configured as described above. Its effects will be explained below.

[0066] Figure 3 This is an explanatory diagram showing the periphery of nozzle 11. (For example...) Figure 3As shown, under the control of the control unit 70, the plasma spraying apparatus 1 supplies spraying powder R1 into the passage 11a inside the nozzle 11 via the feeder 20, and supplies Ar gas (plasma generating gas) into the passage 11a inside the nozzle 11 via the gas supply unit 40. Furthermore, the plasma spraying apparatus 1 causes the Ar gas to flow out from the gas supply unit 40 through the gas flow path 32 into the generation space 30a, thereby forming an Ar gas vortex in the generation space 30a.

[0067] Furthermore, the control unit 70 of the plasma spraying apparatus 1 applies direct current from the direct current power supply 51 to the ejection cylinder 15 (cathode electrode 52) and the metal block 35 (anode electrode 53). As a result, plasma is generated in the gap 80a between the ejection cylinder 15 and the metal block 35. At this time, the generated plasma can be ejected vertically toward the substrate W by the vortex flow of Ar gas. The control unit 70 supplies cooling medium to the cooling medium flow path 67 of the housing 30 using the cooling unit 60. This cools the nozzle body 12 and the metal block 35, which are heated due to plasma spraying. On the other hand, the ejection cylinder 15 is located away from the cooling medium flow path 67, thus maintaining a higher temperature.

[0068] Within the passage 11a of the nozzle 11, the plating powder R1 is transported by the movement of Ar gas, flowing in a straight line in the order of the nozzle body 12 and the ejection cylinder 15. On the inner circumferential surface 182 of the ejection cylinder 15, the ejection orifice 15a is narrow, thus increasing the flow rate of the plating powder R1 and the Ar gas. Conversely, on the inner circumferential surface 183 of the front end of the ejection cylinder 15, the ejection orifice 15a widens towards the nozzle outlet 15b. This conical inner circumferential surface 183 of the front end eliminates areas where the plating powder R1 may stagnate (e.g., corners), allowing the plating powder R1 to be stably ejected from the ejection cylinder 15.

[0069] Therefore, the ejection cylinder 15 can suppress the adhesion of the plating powder R1 to the inner peripheral surface 183 of the front end, and smoothly eject the plating powder R1. Assuming that even if the plating powder R1 adheres to the ejection outlet forming edge 183f, the ejection outlet forming edge 183f, which widens the inner diameter of the ejection outlet 15b, can also prevent the ejection orifice 15a from becoming blocked.

[0070] Furthermore, the front end sidewall 19a of the ejection cylinder 15 is thin-walled due to the front outer peripheral surface 172 and the front inner peripheral surface 183, making it easier to heat up under the action of plasma, for example, to a high temperature of around 3000°C. As a result, the powder R1 for spraying is less likely to adhere to the front end of the ejection cylinder 15. In particular, by widening the front end side of the ejection orifice 15a using the front inner peripheral surface 183, the flow rate of Ar gas on the passage 11a side is reduced, making it easier for plasma to enter the ejection orifice 15a. Therefore, the temperature of the front end sidewall 19a of the ejection cylinder 15 rises more easily, resulting in a melting effect that promotes the powder R1 for spraying.

[0071] As the plating powder R1 flows through the ejection cylinder 15, it is ejected from the ejection port 15b and melted under the heat of the plasma. Thus, the plating powder R1, as a plasma jet P, passes through the jet passage 35a of the metal block 35 and is ejected from the front end of the jet passage 35a toward the surface of the substrate W, thereby forming a plating film F1 on the surface of the substrate W. Since there are no lumps generated by the adhesion of the plating powder R1 in the plasma jet P, the plasma plating apparatus 1 can form the plating film F1 with high precision.

[0072] Figure 4 This is an explanatory diagram illustrating the nozzle used in an evaluation experiment of plasma spraying. Figure 4 (a) shows a case where the ejection cylinder 15 of this embodiment is used. Figure 4 (b) shows the case where the ejection cylinder 90 of the reference example is used. Additionally, as... Figure 4 As shown in (b), the ejection cylinder 90 of the reference example has the same flange 91 and outer peripheral surface 92 as the flange 16 and outer peripheral surface 17 of the ejection cylinder 15. Therefore, the interval D of the gap 80a between the ejection cylinder 90 and the metal block 35 is the same.

[0073] On the other hand, the inner circumferential surface 93 of the ejection cylinder 90 forming the ejection orifice 90a has a base end inner circumferential surface 931 and a body inner circumferential surface 932 with the same diameter as the base end inner circumferential surface 181 and the body inner circumferential surface 182 of the ejection cylinder 15, but the body inner circumferential surface 932 extends to the ejection outlet 90b. In other words, the inner diameter of the ejection outlet 90b of the ejection cylinder 90 remains constant from the body inner circumferential surface 932. Therefore, the front end sidewall portion 94a of the ejection cylinder 90 is formed to be thicker than the front end sidewall portion 19a of the ejection cylinder 15.

[0074] In the evaluation experiment, the same evaluation equipment was used for both the ejection cylinder 15 and the ejection cylinder 90, and plasma spraying was performed under the same process conditions. In the process conditions, the pressure inside the processing container housing the plasma spraying apparatus 1 was set to 20 kPa, the current supplied by the DC power supply 51 was set to 400 A, and the flow rate of Ar gas from the gas supply unit 40 was set to 8 / 18 s / m. Furthermore, the spraying powder R1 used in the evaluation experiment was a mixture of yttrium fluoride (YF3) and yttrium oxide (Y2O3), and the target supply amount of the spraying powder R1 was set to 0.3 g / min. The plasma spraying duration of the evaluation experiment was 60 minutes.

[0075] for Figure 4 In the reference example shown in (b), the weight of the ejector cylinder 90 increased by 0.0318 g after plasma spraying. That is, it can be said that the spraying powder R1 adheres to the ejector cylinder 90.

[0076] In contrast, for Figure 4 The ejector cylinder 15 of this embodiment, shown in (a), loses 0.0054 g in weight after plasma spraying. That is, it can be said that the spraying powder R1 hardly adheres to the ejector cylinder 15. The weight reduction of the ejector cylinder 15 is presumed to be due to the scraping of the ejector cylinder 15 caused by the plasma. Furthermore, the film formation rate and supply rate of plasma spraying are approximately the same in both the case using the ejector cylinder 15 and the case using the ejector cylinder 90. Therefore, it can be confirmed that even with the ejector cylinder 15 of this embodiment, film formation can be performed at the same speed as the ejector cylinder 90 of the reference example.

[0077] Figure 5 This is a graph showing the change in feeder pressure during the evaluation experiment of plasma spraying. The horizontal axis represents time, and the vertical axis represents feeder pressure. The feeder pressure is the pressure (negative pressure) applied to the feeder 20 from the passage 11a of the nozzle 11. Additionally, Figure 5 The time point ta in the chart is the moment when the powder R1 for spraying is supplied to the feeder 20.

[0078] like Figure 5 As shown, the feeder pressure of the ejection cylinder 90 in the reference example (refer to...) Figure 5 (The two dashed lines indicate that) 20 minutes after the start of plasma spraying, the feeder pressure increases. That is, blockage occurs in the ejection orifice 90a of the ejection cylinder 90. Moreover, the feeder pressure of the ejection cylinder 90 continues to rise after 30 minutes, indicating that the blockage of the ejection orifice 90a is progressing.

[0079] In contrast, the feeder pressure of the ejection cylinder 15 in this embodiment (refer to...) Figure 5 The solid line (the line) hardly rises even after time. Therefore, it can be seen that even if plasma spraying continues, the ejection orifice 15a of the ejection cylinder 15 will not become blocked.

[0080] Furthermore, the nozzle 11 (ejection cylinder 15) of the plasma spraying apparatus 1 disclosed herein can be adapted to various variations. Hereinafter, reference will be made to... Figure 6 of (a), Figure 6 (b) will be used to illustrate a modified example of the ejection cylinder 15.

[0081] for Figure 6 In the first modified example shown in (a), the inner circumferential surface 18A of the ejection cylinder 15A has a front end inner circumferential surface 183A that is radially wider outward relative to the body inner circumferential surface 182, but this front end inner circumferential surface 183A has a (non-conical) shape that extends to the ejection port 15b with a constant inner diameter φic. That is, the front end inner circumferential surface 183A is connected to the body inner circumferential surface 182 by means of a stepped end face 184. In the structure having such a front end inner circumferential surface 183A, the ejection cylinder 15A can also widen the inner diameter φic of the front end of the ejection port 15a, making the front end sidewall 19a thin-walled. Therefore, the ejection cylinder 15A can obtain the same effect as the ejection cylinder 15 described above.

[0082] for Figure 6 The inner circumferential surface 18B of the ejection cylinder 15B shown in (b) has a front end inner circumferential surface 183B that widens radially outward in an arc shape when viewed in cross-section along the axial direction. In the structure having such a front end inner circumferential surface 183B, the ejection cylinder 15B can also make the front end sidewall portion 19a thin-walled, achieving the same effect as the ejection cylinder 15 described above.

[0083] The technical concepts and effects of this disclosure described in the above embodiments are described below.

[0084] One aspect of this disclosure is a plasma spraying apparatus 1, which includes: a cylindrical nozzle body 12; a first electrode (ejection cylinders 15, 15A, 15B) detachably disposed at the front end of the nozzle body 12 and having an axis common to the central axis of the nozzle body 12; and a second electrode (metal block 35) disposed outside the first electrode and having an axis common to the central axis of the nozzle body 12. The nozzle body 12 and the first electrode have a continuous passage 11a for gas and powder to flow through. The first electrode has an outlet 15b communicating with the passage 11a and capable of ejecting gas and powder. The inner diameter φic of the outlet 15b is larger than the inner diameter φib of the passage 11a. The plasma spraying apparatus 1 is configured to generate a gas plasma between the first electrode and the second electrode, and to use the plasma to melt the powder ejected from the outlet 15b.

[0085] Based on the above, for the plasma plating apparatus 1, the inner diameter φic of the nozzle 15b is larger than the inner diameter φib of the passage 11a. This prevents the plating powder R1 from easily accumulating on the inner circumferential surface 183 of the front end, allowing for stable ejection of the plating powder R1 from the nozzle 15b. In particular, the larger inner diameter φic of the nozzle 15b results in a thinner wall at the front end of the first electrode (ejection cylinders 15, 15A, 15B), making it easier to heat up and further suppressing the adhesion of the plating powder R1. Consequently, the plasma plating apparatus 1 reduces the likelihood of maintenance and replacement of the first electrode, thereby improving productivity.

[0086] Furthermore, the first electrode (ejection cylinders 15, 15A, 15B) has: a first inner circumferential surface (body inner circumferential surface 182) extending parallel to the axial direction of the first electrode; and a second inner circumferential surface (front end inner circumferential surface 183) whose inner diameter increases radially outward from the end of the first inner circumferential surface near the ejection outlet 15b toward the ejection outlet 15b. Thus, the plasma spraying apparatus 1 can suppress turbulence between the spraying powder R1 and the gas, and can suppress the adhesion of the spraying powder R1 to the front end inner circumferential surface 183.

[0087] Furthermore, the second inner circumferential surface (front end inner circumferential surface 183) has a conical shape whose inner diameter gradually increases radially outward from the end of the first inner circumferential surface (body inner circumferential surface 182) near the nozzle 15b. As a result, the plasma spraying apparatus 1 can spray the spraying powder R1 more smoothly.

[0088] Furthermore, the tilt angle θ of the second inner circumferential surface (front end inner circumferential surface 183) relative to the first inner circumferential surface (body inner circumferential surface 182) is set to a range of 1° to 45°. As a result, the plasma spraying apparatus 1 can adequately ensure the formation range of the front end inner circumferential surface 183 and use plasma to stably heat the front end of the first electrode (nozzle 11).

[0089] Furthermore, the axial length of the second inner circumferential surface (front end inner circumferential surface 183) is less than half the axial length of the first electrode (ejection cylinder 15, 15A, 15B). As a result, the plasma spraying apparatus 1 can sufficiently suppress the adhesion of the spraying powder R1 to the ejection cylinder 15.

[0090] Furthermore, the inner diameter φib of the passage 11a formed by the first inner circumferential surface (the inner circumferential surface 182 of the body) is smaller than the inner diameter φia of the inner circumferential surface of the nozzle body 12 constituting the passage 11a. As a result, the plasma spraying apparatus 1 can increase the flow rate of the spraying powder R1 and the gas at the first inner circumferential surface.

[0091] Furthermore, the inner diameter φic of the nozzle 15b is set to be 1.1 to 2 times the inner diameter φib of the passage 11a formed by the first inner circumferential surface (body inner circumferential surface 182). As a result, the nozzle 15b of the first electrode (ejection cylinder 15, 15A, 15B) is sufficiently widened, which can prevent the spraying powder R1 molten due to plasma spraying from clogging the nozzle 15b.

[0092] Furthermore, the first electrode (ejection cylinders 15, 15A, 15B) is a cathode electrode 52, and the second electrode (metal block 35) is an anode electrode 53. Thus, the plasma spraying apparatus 1 is able to generate plasma between the first electrode and the second electrode.

[0093] Furthermore, the first electrode (ejection cylinders 15, 15A, 15B) has an outer peripheral surface (front end outer peripheral surface 172) whose outer diameter decreases radially inward toward the nozzle 15b. As a result, the plasma spraying apparatus 1 can further make the front end of the first electrode thin-walled, thereby promoting heating.

[0094] Furthermore, the outer peripheral surface (front end outer peripheral surface 172) has a conical shape with its outer diameter gradually decreasing radially inward toward the nozzle 15b. As a result, the plasma generated between the first electrode and the second electrode can move smoothly toward the nozzle 15b side of the first electrode.

[0095] Furthermore, the second electrode (metal block 35) has a space (jet passage 35a) through which the powder ejected from the nozzle 15b passes, and the nozzle 15b of the first electrode (nozzle 11) and the second electrode overlap each other. Thus, the plasma spraying apparatus 1 can bring the first electrode and the second electrode closer together, and can appropriately control the plasma generation position.

[0096] The plasma spraying apparatus of the disclosed embodiments is illustrative and not restrictive in all respects. The embodiments can be modified and altered in a wide variety of ways without departing from the claims and their spirit. The matters described in the above embodiments can also be employed in other structures without contradiction, and furthermore, can be combined without contradiction.

Claims

1. A plasma spraying apparatus, wherein, The plasma spraying device includes: The nozzle body is cylindrical; A cylindrical first electrode, detachably disposed at the front end of the nozzle body, has an axis common to the central axis of the nozzle body; and The second electrode is located outside the first electrode and has an axis that shares the same axis as the central axis of the nozzle body. The nozzle body and the first electrode have a continuous passage for the flow of gas and powder, and the first electrode has an outlet that communicates with the passage and is capable of ejecting the gas and powder. The outer diameter of the front end of the first electrode located at the front end of the nozzle body is smaller than the outer diameter of the outer circumferential surface of the first electrode, which extends along the axial direction of the first electrode with a constant outer diameter. The inner diameter of the nozzle-forming edge, which forms the nozzle outlet using the foremost edge of the first electrode, is greater than the inner diameter of the inner circumferential surface of the body that constitutes at least a portion of the passage of the first electrode on the base end side of the nozzle-forming edge. The plasma spraying apparatus is configured to generate a plasma of the gas between the first electrode and the second electrode, and to use the plasma to melt the powder ejected from the nozzle. The first electrode has a base end inner circumferential surface with an inner diameter that gradually decreases from the base end opening toward the front end, and the body inner circumferential surface of the first electrode extends axially from the base end inner circumferential surface with a constant inner diameter and has an inner diameter smaller than the inner circumferential surface of at least a portion of the passage constituting the nozzle body.

2. The plasma spraying apparatus according to claim 1, wherein, The front end inner circumferential surface extending from the front end of the inner circumferential surface of the body toward the nozzle forming edge has a conical shape with an inner diameter that gradually increases radially outward toward the nozzle forming edge.

3. The plasma spraying apparatus according to claim 2, wherein, The inclination angle of the inner circumferential surface of the front end relative to the extending direction of the inner circumferential surface of the torso is set to a range of 1° to 45°.

4. The plasma spraying apparatus according to claim 2 or 3, wherein, The axial length of the inner circumferential surface of the front end is less than 1 / 2 of the axial length of the first electrode.

5. The plasma spraying apparatus according to any one of claims 1 to 3, wherein, The inner diameter of the ejector nozzle forming edge is set to be in the range of 1.1 to 2 times the inner diameter of the inner circumferential surface of the body.

6. The plasma spraying apparatus according to any one of claims 1 to 3, wherein, The first electrode is a cathode electrode, and the second electrode is an anode electrode.

7. The plasma spraying apparatus according to any one of claims 1 to 3, wherein, The outer peripheral surface of the body of the first electrode, which is closer to the front end of the outer peripheral surface of the body, has a conical shape whose outer diameter gradually decreases radially inward toward the nozzle.

8. The plasma spraying apparatus according to any one of claims 1 to 3, wherein, The second electrode has a space through which the powder ejected from the nozzle passes. The nozzle of the first electrode and the second electrode overlap each other.

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