JP5515277B2 - Plasma spraying equipment - Google Patents

Description

Industrial application fields

  The present invention relates to a composite torch type plasma spraying apparatus in which a material such as metal or ceramic is melted and sprayed onto an object by a high-temperature plasma arc and a film is formed on the surface.

Conventional technology

  As shown in FIG. 4, a main torch 1 and a sub torch 2 whose central axes intersect with each other are provided, and plasma arcs P <b> 1 and P <b> 2 are provided between a main anode 12 included in the main torch 1 and a sub cathode 22 included in the sub torch 2. A composite torch-type plasma spraying apparatus for forming a film has been proposed. According to this plasma spraying apparatus, a fluid material such as a liquid is supplied to the vicinity of the front end portion of the main anode 12 through the material transport tube 11 penetrating the center portion of the main anode 12 and is heated and melted by the plasma P. By flying the particles M2 toward the substrate S, a dense or high-quality film M that covers the substrate S is formed by the material (see Patent Document 1).

However, spitting (excessive) due to the material M1 or a part of the molten particles M2 adhering to the tip of the main anode 12, the vicinity of the opening of the main mantle 14 and the like, and the adhering material being irregularly involved in the plasma P. Large diameter splats (which means a powder material that has solidified after colliding with the base material and flattening), and the diameter is irregular. May occur, and the quality of the film M may deteriorate. Further, when the molten particles M2 are peeled off from the main anode 12 and the main mantle 14 and the like, the surfaces on the main anode 12 and main mantle 14 side are peeled together, so that the main torch 1 is damaged and its life is shortened. Is significantly reduced. Therefore, in order to prevent the material M1 from adhering to the main electrode 12, the main mantle 14 and the like, it has been proposed to provide a gas ejection hole in the main anode 12 (see Patent Document 2).
JP 2002-231498 A JP 2007-090209 A

  However, it has nevertheless been found that there is a very small chance that the quality of the film will be degraded.

  Accordingly, an object of the present invention is to provide a composite torch type plasma spraying apparatus capable of further improving the quality of the coating.

  The inventor of the present application has obtained the following knowledge through experiments. That is, when a high-energy plasma arc is formed to improve the melting efficiency of a fluid material, the main mantle may be partially melted or damaged by the heat of the plasma. On the other hand, when the main mantle 14 is cooled in order to prevent melting of the main mantle 14 shown in FIG. 5, the plasma P contracts due to the thermal pinch effect as shown by the arrows, and FIG. As shown in FIG. 4, although the central portion of the front end of the main anode 12 is recessed in the axial direction, there is a scattering space until the material M1 discharged from the material transport tube 11 contacts the plasma P. Narrow. As a result, the material P comes into contact with the plasma P before it is sufficiently diffused or dispersed. Then, the size of at least a part of the scattering unit of the material M1 is increased, thereby reducing the melting efficiency of the material M1 and increasing the possibility that a part of the material M1 adheres to the main anode 12 or the main mantle 14 or the like. . Further, the dispersion of the size of the scattering unit of the material M1, the size of the molten particles, and the dispersion of the splat diameter are increased, and the possibility that pores or cracks are generated in the film is increased. Further, as described above, the material adhering to the main mantle 14 or the like becomes spitting and is irregularly caught in the plasma P and scattered as molten particles to the base material, which causes a large variation in splat diameter. . The present invention has been completed in view of such knowledge.

The plasma spraying apparatus of the present invention includes a main anode having a material transfer tube penetrating in the axial direction, a main mantle having a main opening surrounding the main anode and positioned axially forward of the main anode, and the main mantle. And a sub-cathode having a central axis intersecting the central axis of the main anode, and a sub-opening surrounding the sub-cathode and positioned in front of the sub-cathode in the axial direction. A plurality of sub-torches having a sub-mantle, and fluidity discharged or diffused from the material transport tube by the plasma formed between the main anode and the sub-cathode through the main opening and the sub-opening. A film composed of the material is produced by heating the material with a molten particle to generate a molten particle and spraying the molten particle on a base disposed in front of the main anode in the axial direction. In the plasma spraying apparatus formed on the substrate, the axial direction rearward of the main anode while continuously reducing the diameter of the main anode from the outside of the material conveying pipe in the radial direction of the main anode A first recess recessed toward the center, and the axial direction rearward of the main anode while reducing the diameter continuously or intermittently from the inner edge of the first recess to the material conveying pipe in the radial direction of the main anode. A second recess that is larger or steeper than the first recess is formed, and the material is discharged or diffused from the material transport pipe and is defined by the second recess and the space after passing through the space defined by the first recess, in contact with the plasma formed for the first time between said main anode and the secondary cathode, this to the main torch and the auxiliary torch are disposed The features. In the present invention, the material transport pipe includes an inner pipe that transports the material, and an outer pipe that is disposed outside the inner pipe and supplies a gas that assists the scattering of the material. preferable.

  According to the plasma spraying apparatus of the present invention, the first recess and the second recess are formed at the tip of the main anode. The “first recess” is recessed toward the axially rear side of the main anode while continuously reducing the diameter from the outside of the material conveying pipe in the radial direction of the main anode. The “second recess” is larger than the first recess toward the rear in the axial direction of the main anode while continuously or intermittently reducing the diameter from the inner edge of the first recess to the material conveying pipe in the radial direction of the main anode. It is steeply depressed. The fluid material discharged from the tip of the material transport tube is sequentially diffused in the space defined by the second recess and the space defined by the first recess, and then the main anode and the sub-cathode. Contact the plasma formed between them. Compared with the case where only the first recess is formed, the space that can be diffused before the material released from the tip of the material transport tube comes into contact with the plasma, as much as the second recess is formed. Is widely secured. Therefore, even if the plasma is constricted by the thermal pinch effect and the diffusion space of the material is narrowed, sufficient diffusion of the material, that is, reduction and equalization of the size of the scattering unit of the material can be achieved. . Further, the cooling of the main mantle by the cooling element is allowed as much as the tightness of the plasma due to the thermal pinch effect is allowed. Further, since the cooling of the main mantle is permitted, the plasma can be increased in energy while preventing the main mantle from being damaged. By reducing the scattering unit of the material as described above and increasing the energy of plasma, the melting efficiency of the material can be improved. Further, the possibility that the material that has not been sufficiently melted adheres to the main mantle or the like and is irregularly involved in the plasma is reduced. In addition, since variations in the size of the material scattering unit and the size of the molten particles are suppressed, variations in the diameter of the splats are also suppressed, and pore formation due to the variations is also suppressed. Therefore, quality can be improved such as further densification of the film.

BEST MODE FOR CARRYING OUT THE INVENTION

  Embodiments of the plasma spraying apparatus of the present invention will be described with reference to the drawings.

  First, the overall configuration of the plasma spraying apparatus will be described. The composite torch type plasma spraying apparatus shown in FIG. 1 has the same configuration as that of the plasma spraying apparatus of the second embodiment of Patent Document 1 except for the essential parts thereof. That is, the plasma spraying apparatus includes a main torch 1 and two sub-torches 2. The main torch 1 and the sub torch 2 are detachably fixed so that insulation is maintained between them.

  The main torch 1 has a main anode 12 having a material transfer tube 11 penetrating in the axial direction, a main mantle 14 having a main opening 142 surrounding the main anode 12 and positioned in front of the main anode 12 in the axial direction, and the main anode 12. And a substantially cylindrical insulator 16 for insulating the main mantle 14 and a cooling element (not shown) for cooling the main mantle 14. As shown in FIG. 2, the material carrying tube 11 is constituted by an inner tube 111 and an outer tube 112 which are coaxial with the main anode 12. The fluid material M1 is conveyed toward the tip through the inner tube 111, and Ar that assists the scattering of the material M1 discharged or ejected from the tip of the inner tube 111 through the inner tube 111 and the outer tube 112. Gas is supplied toward the tip. This gas can function as an auxiliary plasma gas when forming a main plasma arc P1 described later. In addition, the axis | shaft of the material conveyance pipe | tube 11, ie, a double pipe | tube, does not need to correspond with the axis | shaft of the main anode 12 as needed. The main anode 12 is made of a material having high thermal conductivity and electrical conductivity such as copper, and is connected to the positive terminal of the first power source 18 and connected to the positive terminal of the second power source 28 via the switch mechanism 186. It is connected. A detailed configuration of the main anode 12 which is a main part of the plasma spraying apparatus of the present invention will be described later. The main mantle 14 is connected to the negative terminal of the first power supply 18 via the switch mechanism 184. The cooling element is constituted by, for example, a conduit piped inside the main jacket 14 and a cooling medium such as water flowing through the conduit. A main plasma gas inlet 162 for introducing a main plasma gas G 1 such as Ar into the main torch 1 is provided on the side wall of the insulator 16. The main plasma gas G1 introduced into the main plasma gas inlet 162 is introduced to swirl in the circumferential direction of the main torch 1 inside the main torch 1 through a swirl flow forming hole (not shown). Since the structure of the swirl flow forming hole is described in detail in, for example, Patent Document 1, detailed description thereof is omitted in this specification.

  The sub-torch 2 includes a sub-cathode (sub-torch activation electrode) 22, a sub-mantle 24 that surrounds the sub-cathode 22 and has a sub-opening 242 that is positioned in the axial direction of the sub-cathode 22, and And a substantially cylindrical insulator 26 for insulation. The main torch 1 and each sub-torch 2 are arranged so that the axis of the main anode 12 and the axis of the sub-cathode 22 intersect in front of the main anode 12 in the axial direction and in front of the sub-cathode 22 in the axial direction. The two sub-torches 2 have rotational symmetry (two-fold symmetry) around the central axis of the main torch 1 or the main anode 12, and the central axis of each sub-torch 2 or sub-cathode 22 is the center of the main torch 1. It is arranged to face each other so as to intersect at one point of the axis. With such an arrangement, the straightness and stability of the plasma flame P +, which will be described later, are achieved, and as a result, high output of plasma can be achieved. Note that three or more sub-torches 2 may be arranged under the condition that the straightness and stability of the plasma flame P + are achieved. For example, the three sub-torches 3 may be arranged so as to have rotational symmetry (three-fold symmetry) around the central axis of the main torch 1. Each sub-cathode 22 is connected to the negative terminal of the second power supply 28 via the switch mechanism 281 or 282. The sub-cathode 22 of one (the upper side in FIG. 1) sub-torch 2 is connected to the negative terminal of the first power source 18 via the switch mechanism 182. Each sub jacket 24 is connected to the positive terminal of the second power supply 28 via a switch mechanism 283 or 284. The side wall of the insulator 26 is provided with a sub-plasma gas inlet 262 for introducing a sub-plasma gas G 2 such as Ar into the sub-torch 2. The sub-plasma gas G2 introduced into the sub-plasma gas inlet 262 is introduced so as to swirl in the circumferential direction of the sub-torch 2 inside the sub-torch 2 through a swirl flow forming hole (not shown), like the main plasma gas G1. .

  Next, the structure of the main anode 12 which is a main part of the plasma spraying apparatus of the present invention will be described. As shown in FIG. 2, which is a cross-sectional view including the central axis in the vicinity of the front end portion of the main anode 12, the first recess portion 121, the second recess portion 122, and the inclined portion 123 are formed at the front end portion of the main anode 12. Is formed. The first concave portion 121 is continuously reduced in diameter from the outside of the material conveying tube 111 (exactly the outer tube 112) in the radial direction or the y direction of the main anode 12, while being axially rearward of the main anode 12 or in the -x direction. It ’s indented. The second concave portion 122 faces the axially rearward direction of the main anode 12 while continuously reducing the diameter from the inner edge of the first concave portion 121 to the material conveying tube 11 (exactly the outer tube 112) in the radial direction of the main anode 12. It is larger or steeper than the first recess 121. The inclined portion 123 is inclined rearward in the axial direction of the main anode 12 while continuously increasing the diameter from the outer edge 124 of the first recess 121 in the radial direction of the main anode 12. The outer edge of the first recess 124 protrudes forward in the axial direction of the main anode 12 and constitutes an anode point. The inclined portion 123 may be omitted, and the tip end portion of the main anode 12 may be formed so that the diameter of the outer edge of the first recess 121 matches the diameter of the main anode 12.

As shown in FIG. 2, the central axis of the main anode 12 is defined as the x axis, and the axis orthogonal to the central axis and passing through the outer edge 124 of the first recess 121 is defined as the y axis. The fact that the first concave portion 121 is recessed while continuously reducing its diameter means that the first function f ₁ (x) (−x ₁ ≦ x ≦ 0) representing the diameter of the first concave portion 121 at the coordinate x is a continuous function. It means that the derivative df ₁ / dx (representing the degree of inclination of the first recess 121 with respect to the x-axis) is a positive value. Similarly, if the second recess 122 is continuously depressed while being reduced in diameter, the second function f ₂ (x) (−x ₁ −x ₂ ≦ x ≦) representing the diameter of the second recess 122 at the coordinate x. −x ₁ ) is a continuous function and its derivative df ₂ / dx (representing the degree of inclination of the second recess 122 with respect to the x-axis) is a positive value. Further, the fact that the inclined portion 122 is inclined while continuously increasing the diameter means that the third function f ₃ (x) (−x3 ≦ x ≦ 0) representing the diameter of the inclined portion 123 at the coordinate x is a continuous function. It means that the derivative df ₃ / dx (representing the degree of inclination of the inclined portion 123 with respect to the x-axis) is a negative value.

The fact that the second recess 122 is recessed larger than the first recess 121 means that the width of the domain (−x ₁ −x ₂ ≦ x ≦ −x ₁ ) of the second function f ₂ is equal to that of the first function f ₁ . It means that it is larger than the width of the domain (−x ₁ ≦ x ≦ 0), that is, x ₂ is larger than x ₁ . The fact that the second concave portion 122 is steeper than the first concave portion 121 means that, for example, the average value {∫dx (df ₂ / dx)} / x ₂ of the derivative df ₂ / dx of the second function f ₂ This means that the average value {値 dx (df ₁ / dx)} / x ₁ of the derivative df ₁ / dx of the first function f ₁ is greater. Since the value of the derivative df ₁ / dx of the first function f ₁ and the value of the derivative df ₂ / dx of the second function f ₂ are constant in the main anode 12 shown in FIG. The fact that the concave portion is steeper than the one concave portion 121 means that the value of the derivative df ₂ / dx of the second function f ₂ is larger than the value of the derivative df ₁ / dx of the first function f _1. .

Note that the shape of the tip of the main anode 12 shown in FIG. 2 can be variously changed as shown in FIGS. 3 (a) to 3 (d), for example. To gradually increase as the second recess 122 are shown going constant at no + x direction of those derivatives df ₂ / dx of the second function f ₂ is a positive value in FIG. 3 (a), i.e., The second-order derivative d ² f ₂ / dx ^{2 of} the second function f ₂ is formed to be a positive value. The second concave portion 122 shown in FIG. 3B has a derivative df ₂ / dx of the second function f ₂ that is positive, but is not constant but gradually decreases in the + x direction, that is, The second-order derivative d ² f ₂ / dx ^{2 of} the second function f ₂ is formed to be a negative value. The second recess 122 shown in FIG. 3C is formed so as to intermittently reduce the diameter in the axially rearward direction of the main anode 12. The second recess 122, shown in FIG. 3 (c) are formed to be substantially the same diameter as the outer edge 124 of the first recess 121 in almost all domains of the second function f _2. That is, in the second recess 122 shown in FIG. 3C, the derivative df ₂ / dx of the second function f ₂ takes a value close to infinity at x = −x ₁ −x ₂ . It is formed so as to exhibit a behavior close to the δ function, such as 0 in the region. The second recess 122 shown in FIG. 3D is also formed so as to be intermittently reduced in diameter in the axially rearward direction of the main anode 12. The second recess 122 shown in FIG. 3D has a diameter of the material transport pipe 11 in the range of x = −x ₁ −x ₂ to −x ₁ −x ₂₁ −x ₂₂ in the domain of the second function f _2. And a diameter of the outer edge 124 of the first recess 121, and in the case of x = −x ₁ −x ₂₁ −x ₂₂ to −x ₁ −x _21, it is continuously rearward in the axial direction of the main anode 12. The diameter is reduced, and the diameter is the same as the outer edge 124 of the first recess 121 at x = −x ₂ −x ₂₁ to −x ₁ −x ₂ . That is, in the second recess 122 shown in FIG. 3D, the derivative df ₂ / dx of the second function f ₂ takes a value close to infinity at x = −x ₁ −x ₂ , and x = − x ₁ in _{-x 2 ~-x 1 -x 21} -x 22 is 0, x = discontinuously increased in _{-x 1 -x 21 -x 22, x} = -x 1 -x 21 -x ₂₂ in ~-x ₁ -x ₂₁ is a positive constant value, discontinuously decreased at x = -x ₁ -x _21, as is 0 at _{x = -x 1 -x 21 ~-} x 1 Is formed. In addition, if the condition that the depth x ₂ of the second recess 122 is larger than the depth x ₁ of the first recess 121 is satisfied, the first recess 121 is recessed more steeply than the second recess 122. If the condition that the second recess 122 is steeper than the first recess 121 is satisfied, the depth x ₂ of the second recess 122 is greater than the depth x ₁ of the first recess 121. May be small.

  Next, the function of the plasma spraying apparatus having the above configuration will be described.

  First, an inert gas such as Ar is introduced from the main plasma gas inlet 162 as a main plasma gas G1 so as to form a swirling flow in the main torch 1. Further, the switch mechanism 184 is closed in a state where the switch mechanisms 182 and 186 are opened, and a high frequency voltage is applied between the main anode 12 and the main mantle 14 by the first power supply 18. As a result, a main plasma arc P1 is formed from the front end portion of the main anode 12 toward the main opening 142 of the main mantle 14, whereby the main plasma gas G1 is heated and becomes plasma P to become the main opening of the main mantle 14. 142 is discharged from the main torch 1 through 142.

  Next, in one sub-torch 2 (upper side in FIG. 1), an inert gas such as Ar is introduced as a sub-plasma gas G2 from the sub-plasma gas inlet 262 so as to form a swirling flow. Further, the switch mechanisms 281 and 283 are closed in a state where the switch mechanisms 282 and 284 are opened, and a high frequency voltage is applied between the sub-cathode 22 and the sub-mantle 24 by the second power source 28. As a result, a sub-plasma arc P2 is formed from the tip of the sub-cathode 22 toward the sub-opening 242 of the sub-mantle 24, whereby the sub-plasma gas G2 is heated and becomes plasma P, thereby forming the sub-opening 242 of the sub-mantle 24. Through one of the auxiliary torches 2.

  Since the main torch 1 and the sub-torch 2 are arranged so that the central axis of the main anode 12 and the central axis of the sub-cathode 22 intersect in the axial direction as described above, the main torch 1 and the sub-torch 2 are respectively separated from each other. The emitted plasma P intersects in front of the main torch 1 and in front of the auxiliary torch 2. In this state, the switch mechanism 281 is opened, and at the same time, the switch mechanism 182 is closed and the switch mechanisms 184 and 283 are opened. As a result, since the plasma P is conductive, a conductive path is formed by the hairpin-shaped plasma P from the tip of the sub-cathode 22 to the anode point of the main anode 12.

  Immediately thereafter, an inert gas such as Ar is introduced as a secondary plasma gas G2 from the secondary plasma gas inlet 262 so as to form a swirling flow also in the secondary torch 2 on the other side (lower side in FIG. 1). Further, the switch mechanisms 282 and 284 are closed in a state where the switch mechanisms 281 and 283 are opened, and a high frequency voltage is applied between the sub-cathode 22 and the sub-mantle 24 by the second power source 28. As a result, a sub-plasma arc P2 is formed from the tip of the sub-cathode 22 toward the sub-opening 242 of the sub-mantle 24, whereby the sub-plasma gas G2 is heated and becomes plasma P, thereby forming the sub-opening 242 of the sub-mantle 24. Through the other auxiliary torch 2.

  The plasma P emitted from the other sub-torch 2 intersects the hairpin-shaped plasma P extending from the tip of the sub-cathode 22 of one sub-torch 2 to the anode point of the main anode 12. In this state, when the switch mechanism 186 is closed while the switch mechanism 284 is opened, since the plasma P is conductive, the T-shaped plasma P is formed as a whole.

  Through the inner pipe 111 of the material carrying pipe 11, a slurry-like fluid material M1 in which a powdery material is dispersed in a solvent is carried. Instead of the slurry, the precursor or the powdery material itself may be conveyed through the inner tube 111 as the fluid material M1. The material M1 released from the tip of the inner tube 111 is scattered by the momentum of the transporting gas supplied through the outer tube 112. Since the anode point 124 in the main anode 12 is closer to the cathode point in the sub-cathode 22 (the tip of the sub-cathode) than the tip of the material transport tube 11, the center of the plasma does not interfere with the material M1 and the anode point 124 of the plasma P. The high-temperature plasma P is reliably supplied in the direction coaxial with the axis. Even if the material M1 has a high melting point, the radial direction of the main anode 12 is such that it is immediately heated to a high temperature by the plasma P at 10000 ° C. or higher and melts to become molten particles M2 and is accompanied by the plasma flame P +. It goes to the base material S so that it may not spread.

  The plasma flame P + containing the molten particles M2 removes material such as a plasma separation element (for example, useless flame or unmelted particles) immediately before the substrate S in order to reduce the thermal load on the substrate S as necessary. Only the plasma P is separated by the separate gas or separator P-), and immediately after that, the molten particles M2 collide with the substrate S to form the coating M.

  According to the plasma spraying apparatus of the present invention, the first recess 121 and the second recess 122 are formed at the tip of the main anode 12 (see FIG. 2). The first recess 121 is recessed toward the rear in the axial direction of the main anode 12 while continuously reducing the diameter from the outside of the material transport pipe 11 in the radial direction of the main anode 12. The second recess 122 is a first recess toward the rear in the axial direction of the main anode 12 while continuously or intermittently reducing the diameter from the inner edge 124 of the first recess 121 to the material transport tube 11 in the radial direction of the main anode 12. It is larger or sharper than 121. The fluid material M1 discharged from the tip of the material transport tube 11 is sequentially diffused in the space defined by the second recess 122 and the space defined by the first recess 121, and then the main anode. 12 and the plasma P formed between the sub-cathode 22 and the sub-cathode 22. Compared with the case where only the first concave portion 121 is formed by the amount of the second concave portion 122 (see FIG. 5), the material M1 discharged from the tip end portion of the material transport tube 11 is converted into the plasma P. A wide space that can diffuse before contact is secured. For this reason, even if the plasma P is contracted by the thermal pinch effect and the diffusion space of the material M1 is narrowed (see FIG. 5) (see FIG. 5), sufficient diffusion of the material M1, that is, scattering units of the material M1 (in the case of slurry) Can reduce and equalize the size of fine droplets of a solvent containing a powdery material. Further, the cooling of the main mantle 14 by the cooling element is allowed as much as the tightness of the plasma due to the thermal pinch effect is allowed. Further, since the cooling of the main mantle 14 is allowed, the plasma P can be increased in energy while preventing the main mantle 14 from being damaged. By reducing the scattering unit of the material M1 and increasing the energy of the plasma P as described above, the melting efficiency of the material M1 can be improved. And possibility that the material M1 which was not fully fuse | melted will adhere to the main mantle 14 grade | etc., And will be caught in the plasma P irregularly is reduced. Moreover, since the dispersion | variation in the size of the scattering unit of the material M1 and the size of a molten particle is suppressed, the dispersion | variation in the diameter of a splat is also suppressed and the pore formation resulting from the said dispersion | variation is also suppressed. Therefore, the quality of the film M can be improved, such as further densification of the film M (for example, meaning that the porosity of the film is further reduced when the porosity of the film is 10% or less).

  In addition, since the second recess 122 is formed, the tip of the material transport tube 11 is kept away from the plasma P in the axial direction of the main anode 12, and the tip of the material transport tube 11 is damaged by the heat of the plasma P. As a result, it is possible to improve the durability of the entire apparatus.

Configuration explanatory diagram of the plasma spraying apparatus of the present invention Structure explanatory drawing of the main anode in the plasma spraying apparatus of the present invention Other configuration explanatory drawing of the main anode Configuration diagram of conventional plasma spraying equipment Configuration diagram of main anode in conventional plasma spraying equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main torch, 2 ... Sub torch, 11 ... Material conveyance pipe, 12 ... Main anode, 14 ... Main mantle, 18 ... First power source, 22 ... Sub cathode, 24 ... Sub mantle, 28 ... Second power source, 121 ... First recess 122, second recess

Claims (2)

A main anode having a material conveying pipe penetrating in the axial direction; a main mantle having a main opening surrounding the main anode and positioned in front of the main anode in the axial direction; and a cooling element for cooling the main mantle. A plurality of sub-closures having a main torch, a sub-cathode having a central axis intersecting with a central axis of the main anode, and a sub-opening surrounding the sub-cathode and having a sub-opening positioned forward in the axial direction of the sub-cathode. Heating a fluid material discharged or diffused from the material transport tube by plasma formed between the main anode and the sub-cathode through the main opening and the sub-opening. And forming a film composed of the material on the base material by spraying the molten particles onto the base material arranged in front of the main anode in the axial direction. In Ma spraying equipment,
A first recess recessed at the rear end in the axial direction of the main anode while continuously reducing the diameter from the outside of the material conveying pipe in the radial direction of the main anode at the tip of the main anode; A dent larger or steeper than the first recess toward the rear in the axial direction of the main anode while continuously or intermittently reducing the diameter in the radial direction of the anode from the inner edge of the first recess to the material conveying pipe. A second recess is formed ,
The material is discharged or diffused from the material transport pipe and passes between the space defined by the second recess and the space defined by the first recess only after the main anode and the sub-cathode. The plasma spraying apparatus is characterized in that the main torch and the sub-torch are arranged so as to come into contact with the plasma formed on the surface. The plasma spraying device according to claim 1, wherein
  The material transport pipe includes an inner pipe for transporting the material, and an outer pipe that is disposed outside the inner pipe and supplies a gas that assists scattering of the material. .

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