JP7659883B2 - Thermal spraying equipment - Google Patents

Description

The present invention relates to a thermal spraying device.

In recent years, there has been a strong demand for forming a dense thermal spray coating with excellent heat resistance and coating strength on the surface of a coating material while suppressing the occurrence of voids and cracks. As a method for achieving this, Patent Document 1 discloses the use of heat-resistant fine particles as the thermal spray material. Specifically, fine particles are dispersed in an organic solvent to create a fine particle-containing slurry, which is then introduced into a combustion flame in an atomized state, whereby the fine particles are thermally sprayed onto the material to be thermally sprayed while the organic solvent is dissipated.

The thermal spraying device, for example, includes a combustion chamber in which a gas flame is generated by burning a combustion gas, a gas nozzle that supplies the combustion gas to the combustion chamber, and a slurry transport pipe that transports the fine particle-containing slurry toward the combustion chamber. The thermal spraying device sprays the hot fluid in which the fine particle-containing slurry has been introduced into the gas flame toward the material to be thermally sprayed.

JP 2014-213214 A

Patent Document 1 discloses that in order to disperse the particulate-containing slurry evenly in the gas flame, a slurry transport pipe is arranged coaxially inside the gas nozzle, and the particulate-containing slurry is supplied coaxially to the gas flame. In this case, the outlet end of the slurry transport pipe opens into the combustion chamber, and as a result of being exposed to the gas flame, the temperature may rise excessively.

In this case, the fine particle-containing slurry is heated as it passes through the outlet end of the slurry transport pipe. As a result, the organic solvent in the fine particle-containing slurry may disappear, causing the fine particles to adhere to the inside of the slurry transport pipe. This results in a narrowing of the slurry transport pipe, which causes problems in transporting the fine particles.

In addition, if there is a problem with the transport of fine particles, it is necessary to interrupt the thermal spraying process to remove the narrowing of the slurry transport pipe, which results in the problem that thermal spraying cannot be performed for an extended period of time, reducing the efficiency of the thermal spraying process.

The present invention aims to provide a thermal spraying device that can suppress adhesion of fine particles in a mist supply section that sprays a dispersion liquid containing fine particles into a mist, and can suppress clogging of the mist supply section.

One aspect of the present invention is
A tubular mist supplying section that turns a dispersion liquid containing fine particles into a mist and sprays it in a mist supplying direction;
a plurality of flame ejection units arranged at intervals in a radial direction from the mist supply unit to the mist supply unit, and ejecting a flame;
The flame injection section provides a thermal spraying device that heats the mist from the surroundings.

With this configuration, multiple frame injection parts are arranged at radial intervals from the mist supply part, so overheating of the mist supply part is suppressed compared to when the mist supply parts are arranged coaxially inside one frame injection part. As a result, adhesion of fine particles in the mist supply part due to heat is suppressed, and clogging of the mist supply part can be prevented. This also makes it possible to carry out thermal spraying for a long period of time, improving the efficiency of thermal spraying.

The frame injection unit may inject the frame in a frame injection direction inclined radially inward toward the mist supply direction, thereby heating the mist.

The frame ejection section may be arranged so that the central axis of the frame ejection section and the central axis of the mist supply section intersect.

With this configuration, the frame intersects with the mist, allowing the mist to be heated efficiently.

Here, the intersection is not limited to an intersection in the strict geometric sense. In other words, the central axis of the frame ejection unit and the central axis of the mist supply unit do not need to intersect exactly. It is sufficient that the frame ejected from the frame ejection unit and the mist sprayed from the mist supply unit intersect, and the intersection includes not only a strict intersection but also a form that is slightly deviated from the strict intersection within the range where the frame and mist intersect.

The multiple frame injection units may be arranged such that the intersection between the central axis of one of the frame injection units and the central axis of the mist supply unit is offset from the intersection between the central axis of another of the frame injection units and the central axis of the mist supply unit in the mist supply direction.

With this configuration, the frame intersects with the mist at different positions in the mist supply direction, so the mist can be heated at multiple locations, and the range in the mist supply direction over which a specified temperature range is maintained can be extended.

The device may be provided with an angle adjustment mechanism that adjusts the angle of the central axis of the flame spray unit relative to the central axis of the mist supply unit.

With this configuration, the position where the frame and mist intersect can be easily changed. As a result, the range in which a specified temperature range is maintained in the mist supply direction can be adjusted. Generally, the melting point or sintering temperature differs for each spray material, so by adjusting the range in which a specified temperature range is maintained in the spray direction to suitable conditions for each spray material and spraying, the quality of the sprayed coating can be improved.

A position adjustment mechanism may be provided to adjust the position of the frame injection part in the radial direction.

With this configuration, the distance from the mist to the nozzle that sprays the frame of the flame spray unit can be easily changed. This makes it possible to adjust the amount of heat that the frame applies to the mist, and the temperature of the mist can be easily adjusted. As described above, the melting point or sintering temperature differs for each spray material, so the quality of the sprayed coating can be improved by spraying the sprayed spray material at suitable conditions for each spray material.

The present invention can prevent adhesion of the thermal spray material in the mist supply section that sprays the thermal spray material, and can prevent clogging of the mist supply section.

1 is a schematic diagram of a thermal spraying device according to an embodiment of the present invention. FIG. 2 is a view taken along the X arrow in FIG. FIG. 2 is a view of the thermal spray nozzle according to the embodiment as viewed from the radial outside. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 6 is a diagram showing the relationship between the distance from the mist supply nozzle and the temperature of the mist. FIG. 11 is a diagram showing the periphery of a mist supply nozzle according to a modified example of the embodiment. In Example 1, an optical microscope image of a mist sprayed onto a transparent substrate with an opening area of the inner tube being 6 ^mm2 . In Example 1, an optical microscope image of a mist sprayed onto a transparent substrate with an opening area of the inner tube being 12 ^mm2 . In Example 1, an optical microscope image of a mist sprayed onto a transparent substrate with an opening area of the inner tube being 18 ^mm2 . 4 is a secondary electron image of a cross section including the thickness direction of the aluminum oxide film of Example 1. EBSD mapping of FIG. 8A. 13 is a secondary electron image of a cross section including a thickness direction of the yttrium oxide coating of Example 2. 4 is a secondary electron image of a cross section including a thickness direction of an yttrium oxide coating of a comparative example. 9B is a secondary electron image of a cross section including the thickness direction of the yttrium oxide coating of Example 2, taken at a position different from that of FIG. 9A. EBSD mapping of FIG. 9C.

The following describes an embodiment of the present invention with reference to the attached drawings.

Figure 1 is a schematic diagram of a thermal spraying device 1 according to this embodiment. Figure 2 is a view taken along the X-arrow in Figure 1. The thermal spraying device 1 uses a fine particle-containing slurry, in which fine particles are dispersed in a dispersion medium such as an organic solvent, as a thermal spraying material, and sprays the fine particles onto a workpiece W. In the following description, the direction in which the fine particles are sprayed from the thermal spraying device 1 onto the workpiece W may be referred to as the forward and backward direction of the thermal spraying device 1. The fine particle-containing slurry of this embodiment is an example of a dispersion liquid containing fine particles according to the present invention.

The fine particles contained in the fine particle-containing slurry are, for example, ceramic fine particles. Examples of ceramics include oxide ceramics, nitride ceramics, carbide ceramics, and boride ceramics. Among them, oxide ceramics are preferred because of their excellent chemical stability in an oxidizing atmosphere.

[Overall configuration]
1 and 2, the thermal spraying device 1 includes a mist supply unit 10 that turns fine particle-containing slurry into mist and sprays it, and a plurality of (six in this embodiment) thermal spraying units 20A to 20F that spray gas flames (hereinafter, sometimes referred to as flames) in which oxygen and fuel are combusted. In the following description, when there is no need to particularly distinguish between the thermal spraying units 20A to 20F, one of them may be simply referred to as the thermal spraying unit 20.

In the following description, the side of the thermal spraying device 1 where the material W to be sprayed is placed (the right side in Figure 1) may be referred to as the front side, and the opposite side (the left side in Figure 1) may be referred to as the rear side.

[Mist supply unit]
As shown in FIG. 1 , the mist supply unit 10 includes a main casing 11 and a mist supply nozzle 12 attached to the front end of the main casing 11 .

The main casing 11 is a generally cylindrical member extending in the front-rear direction. A spray medium inlet 11a is provided at the rear end of the main casing 11. A spray medium supplying means 2 is connected to the spray medium inlet 11a. The spray medium supplying means 2 supplies a spray medium (e.g., compressed air, pressurized oxygen) to the spray medium inlet 11a.

In addition, a slurry introduction section 11b is provided in front of the spray medium introduction section 11a of the main casing 11. A slurry supply means 3 is connected to the slurry introduction section 11b.

The slurry supplying means 3 supplies the slurry containing fine particles to the slurry introduction section 11b. The slurry containing fine particles is obtained by dispersing fine particles in a dispersion medium. Since the fine particles are dispersed in the dispersion medium in the slurry containing fine particles supplied from the slurry supplying means 3, the fine particles are supplied to the mist supplying unit 10 without agglomerating. The dispersion medium in this embodiment is an organic solvent. The viscosity of the dispersion medium is preferably 10,000 mPa·s or less, since if the viscosity is too high, the fluidity will be lost.

The main casing 11 is provided with a communication passage 11c that extends forward from the spray medium introduction section 11a. The communication passage 11c also communicates with the mist supply nozzle 12.

The main casing 11 has a double-tube structure having an inner tube through which the spray medium introduced from the spray medium introduction section 11a flows, and an outer tube arranged at a distance from the outer periphery of the inner tube. The inner tube defines a part of the communication passage 11c. In addition, the fine particle-containing slurry introduced from the slurry introduction section 11b is supplied between the inner tube and the outer tube. The fine particle-containing slurry supplied between the inner tube and the outer tube is supplied to the communication passage 11c through an opening provided in the inner tube at the front end of the main casing 11. The fine particle-containing slurry supplied to the communication passage 11c is fluidized and atomized by receiving a shear force from the spray medium introduced from the spray medium introduction section 11a in the communication passage 11c. As described above, the communication passage 11c is connected to the mist supply nozzle 12. Therefore, the atomized fine particle-containing slurry is supplied to the mist supply nozzle 12.

The mist supply nozzle 12 is a cylindrical member extending in the front-rear direction. That is, the central axis C1 of the mist supply nozzle 12 in this embodiment extends in the front-rear direction. The mist supply nozzle 12 is also arranged coaxially with the main casing 11. The mist supply nozzle 12 in this embodiment is an example of a mist supply unit according to the present invention.

In the following description, the circumferential direction centered on the central axis C1 of the mist supply nozzle 12 may be referred to simply as the circumferential direction, and the radial direction centered on the central axis C1 of the mist supply nozzle 12 may be referred to simply as the radial direction.

As clearly shown in FIG. 1, the atomized fine particle-containing slurry is sprayed in a mist supply direction D1 from the spray port 12a of the mist supply nozzle 12. Here, the "mist supply direction D1" refers to the direction in which the atomized fine particle-containing slurry is sprayed as a mist on a cross section including the central axis C1 of the mist supply nozzle 12.

The average droplet diameter of the mist sprayed from the mist supply nozzle 12 is preferably 100 μm or less. If the average droplet diameter of the mist exceeds 100 μm, even if the mist is heated by the flame sprayed from the thermal spray unit 20, it is difficult to uniformly heat each fine particle without instantly exposing each fine particle (specifically, without the dispersion medium contained in the mist being decomposed and evaporated (or simply evaporated)). Therefore, the average droplet diameter of the mist is 100 μm or less, preferably 50 μm or less, and more preferably 10 μm or less. The lower limit of the average droplet diameter of the mist is not particularly limited, but can be, for example, equal to or greater than the average particle diameter of the fine particles. The average droplet diameter of the mist can be determined by spraying the mist on a transparent substrate, selecting multiple droplets (e.g., 8 or more) from the optical microscope image, and calculating the median diameter. In addition, the maximum droplet diameter of the mist is preferably 500 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less.

[Thermal spray unit]
1 and 2, each of the thermal spray units 20A to 20F includes a thermal spray nozzle 21 and a base member 22 that supports the thermal spray nozzle 21. That is, the thermal spray device 1 of this embodiment includes six thermal spray nozzles 21. The thermal spray nozzle 21 of this embodiment is an example of a flame injection section according to the present invention.

As shown in FIG. 2, the thermal spray units 20A-20F are arranged at equal intervals in the circumferential direction centered on the central axis C1 of the mist supply nozzle 12. The thermal spray units 20 are fixed to the annular ring member 30 by connecting the base member 22 to the ring member 30. The annular ring member 30 is fixed to the mist supply unit 10, although not shown.

The thermal spray nozzles 21 are arranged at intervals from the mist supply unit 10 so as to surround the mist supply nozzle 12. More specifically, the thermal spray nozzles 21 are arranged at intervals from the mist supply nozzle 12 of the mist supply unit 10 in the radial direction from the central axis C1 of the mist supply nozzle 12. In other words, the thermal spray nozzles 21 and the mist supply nozzle 12 are provided separately. In addition, the six thermal spray nozzles 21 are arranged at equal intervals in the circumferential direction centered on the central axis C1 of the mist supply nozzle 12.

Referring to FIG. 1, the thermal spray nozzle 21 is provided with a combustion gas inlet 21a. The combustion gas inlet 21a is connected to a combustion gas supply means 4. As a result, a mixed gas of a combustible gas and a combustion supporting gas is supplied from the combustion gas supply means 4 to the thermal spray nozzle 21.

An ignition mechanism (not shown) is provided near the nozzle 21b of the thermal spray nozzle 21. This ignition mechanism ignites a mixed gas of flammable gas and combustion-supporting gas, causing a flame to be sprayed from the thermal spray nozzle 21. The thermal spray nozzle 21 sprays a flame to heat the mist sprayed from the mist supply nozzle 12 from the surrounding area. Specifically, the thermal spray nozzle 21 sprays a flame to heat the mist sprayed from the mist supply nozzle 12 from the radial outside around the central axis C1 of the mist supply nozzle 12.

Examples of combustible gases include hydrocarbons such as acetylene, ethylene, propane, and propylene, as well as hydrogen. Examples of combustion supporting gases include oxygen. The temperature of the fine particles contained in the mist can be controlled by the type of combustible gas and combustion supporting gas, the supply amount of each of the combustible gas and combustion supporting gas, and the positional relationship between the mist supply unit 10 and the thermal spray nozzle 21. In this embodiment, acetylene is used as the combustible gas, and oxygen is used as the combustion supporting gas.

The thermal spray nozzle 21 of this embodiment is also provided with a hydrogen inlet 21c. A hydrogen supply means 5 is connected to the hydrogen inlet 21c. This allows hydrogen gas to be supplied to the thermal spray nozzle 21.

The pressure of acetylene, which is used as the combustible gas in this embodiment, is restricted by law. In contrast, there is no such pressure restriction for hydrogen. Therefore, by supplying high-pressure hydrogen to the thermal spray nozzle 21 in addition to the combustion gas, the speed of the combustion gas is increased.

As shown clearly in FIG. 1, the thermal spray nozzle 21 is positioned so that the central axis C2 of the thermal spray nozzle 21 is inclined radially inward toward the mist supply direction D1 (from the rear side to the front side in FIG. 1).

The thermal spray nozzle 21 sprays the frame from the nozzle 21b in a frame spray direction D2. Here, "frame spray direction D2" refers to the direction in which the frame is sprayed in a cross section including the central axis C2 of the nozzle 21b of the thermal spray nozzle 21. The frame spray direction D2 of each of the thermal spray units 20A to 20F extends along the central axis C2 of each of the thermal spray nozzles 21. In other words, the frame spray direction D2 of each of the thermal spray units 20A to 20F is inclined radially inward toward the mist supply direction D1 (from the rear to the front in FIG. 1).

In addition, in this embodiment, the central axis C2 of each spray nozzle 21 of the spray units 20A to 20F and the central axis C1 of the mist supply nozzle 12 have an intersection point P. In this embodiment, the spray units 20A to 20F share one intersection point P. In other words, the central axis C2 of each spray nozzle 21 of the spray units 20A to 20F intersects with the central axis C1 of the mist supply nozzle 12 at the single intersection point P.

The angle θ of the central axis C2 of the thermal spray nozzle 21 relative to the central axis C1 of the mist supply nozzle 12 can be adjusted within a range of 0° or more and less than 90°. In other words, the mist supply nozzle 12 and the thermal spray nozzle 21 may be arranged so that the central axis C1 of the mist supply nozzle 12 and the central axis C2 of the thermal spray nozzle 21 are parallel to each other.

It is preferable that the distance L1 between the intersection point P and the center of the spray nozzle 12a of the mist supply nozzle 12 is 5 mm or more. This prevents the spray nozzle 12a of the mist supply nozzle 12 from being heated by the frame.

As described above, the thermal spray nozzle 21 is disposed at a radial distance from the mist supply nozzle 12 of the mist supply unit 10. It is preferable that the radial distance L2 between the center of the thermal spray nozzle 21 and the center of the mist supply nozzle 12 is 1 mm or more.

It is preferable that the center position of the injection port 21b of the thermal spray nozzle 21 and the center position of the spray port 12a of the mist supply nozzle 12 are arranged so as to satisfy the following formula (1).
-10≦x1≦100...(1)

Here, x1 [mm] is the position of the center of the nozzle 21b of the thermal spray nozzle 21 on the x-axis when the mist supply direction D1 from the spray nozzle 12a of the mist supply nozzle 12 is defined as the x-axis, the position of the center of the spray nozzle 12a of the mist supply nozzle 12 on the x-axis is defined as x=0, and the direction from the position of the center of the spray nozzle 12a of the mist supply nozzle 12 toward the material W to be sprayed is defined as the positive direction on the x-axis.

By making x1 ≧-10 mm, heating of the spray nozzle 12a of the mist supply nozzle 12 by the frame can be suppressed. In addition, it is preferable that x1 ≧-10 mm in at least one of the multiple thermal spray nozzles 21, and it is more preferable that x1 ≧-10 mm in all of the multiple thermal spray nozzles 21.

On the other hand, by setting x1≦100 mm, it is easier to heat the mist efficiently, which is preferable. It is preferable that x1≦100 mm in at least one of the multiple thermal spray nozzles 21, and it is more preferable that x1≦100 mm in all of the multiple thermal spray nozzles 21.

Figure 3 is a view of the thermal spray nozzle 21 of this embodiment as seen from the radial outside. Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3. Note that the combustion gas introduction section 21a and the hydrogen introduction section 21c are omitted from Figure 3. Figure 4 also shows the thermal spray nozzle 21, as well as the base member 22 and the ring member 30.

Referring to Figures 3 and 4, a pair of support plates 23 are attached to the thermal spray nozzle 21. The pair of support plates 23 also hold a slide block 24 and an angle adjustment ring 25.

The pair of support plates 23 are plate-shaped members extending in the front-rear direction. The pair of support plates 23 are fixed to the thermal spray nozzle 21.

The slide block 24 is sandwiched between a pair of support plates 23 and is supported rotatably relative to the pair of support plates 23 by pins 24a. The slide block 24 also has a screw hole 24b that penetrates radially.

The angle adjustment ring 25 is sandwiched between a pair of support plates 23 and is supported rotatably relative to the pair of support plates 23 by pins 25a. The angle adjustment ring 25 also has a screw hole 25b that penetrates in the radial direction.

As shown in FIG. 4, the base member 22 is provided with a guide groove 22a for guiding the slide block 24 in the radial direction. In other words, the guide groove 22a extends in the radial direction. The inner shape of the guide groove 22a is slightly larger than the outer shape of the slide block 24, which allows the slide block 24 to slide radially within the guide groove 22a.

A first shaft 26 rotatably supported by the base member 22 is disposed within the guide groove 22a. The first shaft 26 is attached to the base member 22 so as to extend radially. The first shaft 26 is provided with a threaded portion 26a. The threaded portion 26a of the first shaft 26 is screwed into the threaded hole 24b of the slide block 24. As a result, when the first shaft 26 rotates, the slide block 24 moves radially inward or outward along the guide groove 22a.

The second shaft 27 is rotatably supported on the base member 22 behind the first shaft 26. The second shaft 27 is attached to the base member 22 so as to extend in the radial direction. The second shaft 27 is provided with a screw portion 27a. The screw portion 27a of the second shaft 27 is screwed into the screw hole 25b of the angle adjustment ring 25. As a result, when the second shaft 27 rotates, the angle adjustment ring 25 moves radially inward or outward along the second shaft 27.

The attitude of the thermal spray nozzle 21 is adjusted by adjusting the radial position of the slide block 24 and the radial position of the angle adjustment ring 25. Specifically, the angle θ (shown in FIG. 1) of the central axis C2 of the thermal spray nozzle 21 relative to the central axis C1 of the mist supply nozzle 12 is adjusted by adjusting the radial position of the slide block 24 and the radial position of the angle adjustment ring 25. For example, the angle θ increases by moving the angle adjustment ring 25 radially outward while keeping the radial position of the slide block 24 fixed.

The radial position of the thermal spray nozzle 21 is adjusted by adjusting the radial position of the slide block 24 and the radial position of the angle adjustment ring 25. For example, when the slide block 24 and the angle adjustment ring 25 are moved radially outward or inward by the same amount, the thermal spray nozzle 21 moves radially outward or inward while maintaining its posture.

The thermal spray unit 20 of this embodiment functions as an angle adjustment mechanism that adjusts the angle θ of the central axis C2 of the thermal spray nozzle 21 relative to the central axis C1 of the mist supply nozzle 12, and functions as a position adjustment mechanism that adjusts the radial position of the thermal spray nozzle 21. In this embodiment, the angle adjustment mechanism and the position adjustment mechanism include at least a pair of support plates 23, a slide block 24, an angle adjustment ring 25, a base member 22, a first shaft 26, and a second shaft 27.

Figure 5 is a diagram showing the relationship between the distance in the mist supply direction D1 from the mist supply nozzle 12 of this embodiment and the temperature of the mist. In Figure 5, the horizontal axis is the distance in the mist supply direction D1 from the spray port 12a of the mist supply nozzle 12 [arbitrary scale], and the vertical axis is the temperature of the mist [arbitrary scale]. In Figure 5, the present embodiment in which multiple thermal spray nozzles 21 are spaced apart radially from the mist supply nozzle 12 is shown by solid lines, and a modified example in which the mist supply nozzle is arranged coaxially with one thermal spray nozzle is shown by dashed lines.

Referring to FIG. 5, in this embodiment (solid line), the temperature of the mist rises gradually and then rises sharply as the distance from the outlet 21b of the mist supply nozzle 12 increases. After that, the temperature of the mist remains in a constant temperature range, and then gradually drops.

On the other hand, in the modified example (dashed line), the temperature of the mist increases approximately linearly as the distance from the outlet 21b of the mist supply nozzle 12 increases, and after reaching a maximum temperature, it begins to decrease.

Comparing this embodiment (solid line) with the modified example (dashed line), in this embodiment, the temperature rise of the mist near the outlet 21b of the mist supply nozzle 12 (region R1 in the figure) is suppressed more than in the modified example. Also, in this embodiment, after the temperature of the mist rises to a predetermined temperature, there is a region (region R2 in the figure) where the predetermined temperature range is maintained, whereas in the modified example, after the temperature of the mist reaches its maximum value, it begins to decrease without maintaining that temperature.

The thermal spraying device 1 of this embodiment provides the following effects:

Since multiple thermal spray nozzles 21 are arranged at radial intervals from the mist supply nozzle 12, overheating of the mist supply nozzle 12 is suppressed compared to when the mist supply nozzles 12 are arranged coaxially inside one thermal spray nozzle 21. As a result, adhesion of fine particles in the mist supply nozzle 12 due to heat is suppressed, and clogging of the mist supply nozzle 12 can be prevented. This also makes it possible to carry out thermal spraying for a long period of time, improving the efficiency of thermal spraying.

In addition, since the multiple thermal spray nozzles 21 are arranged to surround the mist supply nozzle 12, the mist sprayed from the mist supply nozzle 12 is sprayed toward the material to be sprayed W while being enveloped in the frame ejected from the multiple thermal spray nozzles 21. As a result, the amount of mist sprayed from the mist supply nozzle 12 that adheres to the material to be sprayed W is prevented from decreasing, and a decrease in the efficiency of thermal spraying is prevented.

The central axis C1 of the mist supply nozzle 12 and the central axis C2 of the thermal spray nozzle 21 intersect. This allows the frame to intersect with the mist, allowing the mist to be heated efficiently.

In addition, in this embodiment, a predetermined temperature range (a temperature range in which the mist temperature is 0.4 times or more the melting point of the thermal spray material and is below the melting point) is maintained (region R2 in Figure 5), which promotes sintering of the thermal spray material such as a slurry containing fine particles, making it easier for the thermal spray materials to bond together. As a result, the quality of the thermal spray coating can be improved. Here, as described above, the predetermined temperature range is preferably a temperature of the mist that is 0.4 times or more the melting point of the thermal spray material and is below the melting point, but is not limited to this. In other words, depending on the type of thermal spray material used or the characteristics of the thermal spray coating to be obtained, the temperature of the mist may be maintained at a temperature less than 0.4 times the melting point, or may be maintained at a temperature above the melting point.

The thermal spraying device 1 has an angle adjustment mechanism that adjusts the angle of the central axis C2 of the thermal spraying nozzle 21 relative to the central axis C1 of the mist supply nozzle 12. The position where the frame and the mist intersect can be easily changed. As a result, the range in which a specified temperature range is maintained in the mist supply direction D1 can be adjusted. Since the melting point or sintering temperature generally differs for each thermal spraying material, the quality of the thermal sprayed coating can be improved by adjusting the range in which a specified temperature range is maintained in the thermal spraying direction to suitable conditions for each thermal spraying material.

Since the thermal spraying device 1 has a position adjustment mechanism that adjusts the radial position of the thermal spraying nozzle 21, the distance between the mist and the nozzle 21b that sprays the frame of the thermal spraying nozzle 21 can be easily changed. This makes it possible to adjust the amount of heat applied to the mist by the frame, and the temperature of the mist can be easily adjusted. As described above, the melting point or sintering temperature differs for each thermal spraying material, so the quality of the thermal sprayed coating can be improved by adjusting the temperature of the sprayed thermal spraying material to suitable conditions for each thermal spraying material before thermal spraying.

(Modification)
FIG. 6 is a diagram showing the periphery of the mist supply nozzle 12 in a modified example of the thermal spraying device 1 of the present embodiment.

Referring to FIG. 6, the central axis C2 of the thermal spray nozzle 21 of the thermal spray unit 20A and the central axis C1 of the mist supply nozzle 12 have an intersection point P1. In addition, the central axis C1 of the thermal spray nozzle 21 of the thermal spray unit 20A and the central axis C2 of the mist supply nozzle 12 form an angle θ1.

The central axis C2 of the spray nozzle 21 of the spray unit 20D and the central axis C1 of the mist supply nozzle 12 have an intersection P2. The central axis C1 of the spray nozzle 21 of the spray unit 20D and the central axis C2 of the mist supply nozzle 12 form an angle θ2 different from the above angle θ1. As a result, the intersection P1 and the intersection P2 are formed at positions offset in the mist supply direction D1 (front-back direction). Although not shown, the spray units 20A, 20C, and 20E share one intersection P1, and the spray units 20B, 20D, and 20F share one intersection P2.

It is preferable that at least one of the distances L11, L12 between the intersection points P1, P2 and the center of the spray nozzle 12a of the mist supply nozzle 12 is 5 mm or more. This makes it possible to prevent the spray nozzle 12a of the mist supply nozzle 12 from being heated by the frame.

With the configuration of this modified example, the frame intersects with the mist at different positions in the mist supply direction D1, so the range in which a specified temperature range is maintained in the mist supply direction D1 can be extended.

In the above modified example, the position of the intersection P between the central axis C2 of the spray nozzle 21 of the spray unit 20 and the central axis C1 of the mist supply nozzle 12 in the mist supply direction D1 was adjusted by adjusting the angle θ of the central axis C2 of the spray nozzle 21 relative to the central axis C1 of the mist supply nozzle 12, but this is not limited to this. In other words, the position of the intersection P between the central axis C2 of the spray nozzle 21 of the spray unit 20 and the central axis C1 of the mist supply nozzle 12 in the mist supply direction D1 may be adjusted by adjusting the radial position of the spray nozzle 21.

In the above modified example, each spray nozzle 21 may be arranged so that the intersections between the central axis C1 of each spray nozzle 21 of the spray units 20A to 20F and the central axis C1 of the mist supply nozzle 12 are formed at different positions in the mist supply direction D1 (front-to-back direction). In this case, each spray nozzle 21 may be arranged so that the locus connecting the intersections P between the central axis C1 of each spray nozzle 21 of the spray units 20A to 20F and the central axis C1 of the mist supply nozzle 12 forms a spiral.

The following provides a more detailed explanation of the embodiments of the present invention, using examples. The embodiments of the present invention are not limited to the following examples, and may be modified as appropriate within the scope of the purpose described above and below, and all such modifications are within the technical scope of the embodiments of the present invention.

Example 1
In Example 1, aluminum oxide fine particles having an α phase were used as the ceramic fine particles.

First, aluminum oxide fine particles having an α phase and an average particle size of 500 nm (manufactured by Nippon Light Metals Co., Ltd., product name: SMN-22) were added to a liquid organic compound (acrylate monomer and/or acrylate oligomer) (manufactured by JSR Corporation, product name: KC1278) so that the volume was approximately 40%. Using a rotation-revolution mixer (manufactured by Shashin Kagaku Co., Ltd., product name: SK-350T), the dispersion containing the aluminum oxide fine particles and the liquid organic compound was stirred while degassing. The viscosity of the liquid organic compound was 100 mPa·s or less at room temperature, and the operating conditions of the rotation-revolution mixer were a rotation speed of 400 rpm, a revolution speed of 1200 rpm, and a mixing time of 15 minutes.

Next, the obtained dispersion was turned into a mist by the mist supply unit 10. In this case, the pressure of the compressed air for spraying the mist was fixed at 0.8 MPa, and the opening area of the opening provided in the inner tube of the main casing 11 of the mist supply unit 10 was changed to 6 mm ² , 12 mm ² , and 18 mm ^2. The obtained mist was sprayed onto a transparent substrate without heating by a flame sprayed from the thermal spray nozzle 21, and observed under an optical microscope.

7A to 7C show optical microscope images of the mist sprayed on the transparent substrate under each condition. In FIG. 7A, the opening area was set to 6 ^mm2 , and the average droplet diameter of the mist was 0.98 μm, and the maximum droplet diameter was 2.82 μm. In FIG. 7B, the opening area was set to 12 ^mm2 , and the average droplet diameter of the mist was 2.01 μm, and the maximum droplet diameter was 3.76 μm. In FIG. 7C, the opening area was set to 18 ^mm2 , and the average droplet diameter of the mist was 1.08 μm, and the maximum droplet diameter was 6.33 μm.

The mist obtained by setting the pressure of the compressed air to 0.8 MPa and the opening area to 12 ^mm2 was sprayed from the spray port 12a of the mist supply nozzle 12 toward the material W to be sprayed, and the material W was heated by injecting a flame using six thermal spray nozzles 21. All six thermal spray nozzles 21 were gas flame guns, and were arranged around the mist supply nozzle 12 at a distance from the mist supply nozzle 12, and were arranged at equal intervals in a concentric circle with the mist supply nozzle 12 as the central axis. The central axis C2 of the six thermal spray nozzles 21 intersected with the central axis C1 of the mist supply nozzle 12 at one intersection. The six thermal spray nozzles 21 were arranged so that the parameters (x1, L1, and θ) related to the position of the thermal spray nozzle 21 were all equal, and were (x1: +9.2 mm, L1: 43.9 mm, and θ: 18.0°), respectively.

Acetylene was used as the combustible gas and oxygen as the combustion supporting gas, the acetylene gas pressure was 0.13 MPa, the acetylene gas flow rate was 55 L/min, the oxygen gas pressure was 5 MPa, and the oxygen gas flow rate was 200 L/min.

The temperature of the aluminum oxide microparticles heated by the frame was confirmed by exposing materials with known melting points (aluminum oxide (melting point 2055°C) and iron (melting point 1538°C) to the frame to see if they melted. As a result, the aluminum oxide surface did not melt, but the iron surface did. Therefore, it can be said that the temperature of the aluminum oxide microparticles heated by the frame was greater than 1538°C and less than 2055°C.

SUS304 was used as the material W to be sprayed, and aluminum oxide fine particles heated by the above-mentioned frame were deposited on the material W. The temperature of the material W to be sprayed was left as it was (room temperature), and the distance between the material W to be sprayed and the center of the spray nozzle 12a of the mist supply nozzle 12 was 105 mm. The film formation speed for the material W to be sprayed (25 cm square) was 80 μm/sec or more.

A Schottky field emission scanning electron microscope (Hitachi High-Tech Corporation, product name: SU7000) was used to obtain a secondary electron image of the cross section of the obtained coating, including the thickness direction, and its EBSD mapping image, at an acceleration voltage of 10 kV.

Figure 8A is a secondary electron image of a cross section including the thickness direction of the aluminum oxide coating of Example 1. Figure 8B is its EBSD mapping. Note that for Figure 8B, an original drawing in which the differences in crystal phases can be identified by color has been submitted as a document submitted at the same time as this application in order to enable a more detailed understanding of the differences in crystal phases. Please refer to this original drawing as well if necessary.

In Figure 8B, yellow indicates alpha-phase aluminum, red indicates gamma-phase aluminum, and black indicates areas where the signal level was below a certain level (voids, etc.). No amorphous areas were identified in Figure 8B. The ratio of alpha-phase aluminum oxide to gamma-phase aluminum oxide was approximately 1:1, and alpha-phase aluminum oxide was maintained in most of the coating.

Example 2
In Example 2, yttrium oxide fine particles were used as the ceramic fine particles.

First, yttrium oxide microparticles with an average particle size of 2 μm (manufactured by Shin-Etsu Chemical Co., Ltd., product name: Y-03-922) were added to a liquid organic compound (acrylate monomer and/or acrylate oligomer) (manufactured by JSR Corporation, product name: KC1278) so that the volume was approximately 40%. Using a rotation-revolution mixer (manufactured by Shashin Kagaku Co., Ltd., product name: SK-350T), the dispersion containing the aluminum oxide microparticles and the liquid organic compound was stirred while degassing. The operating conditions of the rotation-revolution mixer were a rotation speed of 400 rpm, a revolution speed of 1200 rpm, and a mixing time of 15 minutes.

Next, the obtained dispersion liquid was made into a mist by the mist supply unit 10. Regarding the average droplet diameter of the mist, the pressure of the compressed air for spraying the mist was fixed at 0.8 MPa, and the opening area of the opening provided in the inner tube of the main casing 11 of the mist supply unit 10 was set to 12 ^mm2 . The obtained mist was sprayed onto a transparent substrate. From the results of Example 1 (FIG. 7B), it is considered that the average droplet diameter of the mist was at most 100 μm or less, and the maximum droplet diameter was at most 500 μm or less.

The mist obtained by setting the pressure of compressed air to 0.8 MPa and the opening area to 12 ^mm2 was sprayed from the spray port 12a of the mist supply nozzle 12, and heated by injecting flame using six thermal spray nozzles 21. All six thermal spray nozzles 21 were gas flame guns, and were arranged around the mist supply nozzle 12 at a distance from the mist supply nozzle 12, and were arranged at equal intervals in a concentric circle with the mist supply nozzle 12 as the central axis. The central axis C2 of the six thermal spray nozzles 21 intersected with the central axis C1 of the mist supply nozzle 12 at one intersection. The six thermal spray nozzles 21 were arranged so that the parameters (x1, L1, and θ) related to the position of the thermal spray nozzle 21 were all equal, and were (x1: +9.3 mm, L1: 46.4 m, and θ: 17.3°), respectively.

Acetylene was used as the combustible gas and oxygen as the combustion supporting gas, the acetylene gas pressure was 0.13 MPa, the acetylene gas flow rate was 55 L/min, the oxygen gas pressure was 5 MPa, and the oxygen gas flow rate was 200 L/min.

The temperature of the yttrium oxide microparticles heated by the frame was confirmed by exposing materials with known melting points (aluminum oxide (melting point 2055°C) and iron (melting point 1538°C) to the frame to see if they melted. As a result, the aluminum oxide surface did not melt, but the iron surface did. Therefore, it can be said that the temperature of the yttrium oxide microparticles heated by the frame was 1538°C or higher (i.e., 0.63 times or higher than the melting point of yttrium oxide (2430°C)) and less than 2055°C.

SUS304 was used as the material W to be sprayed, and yttria oxide fine particles heated by the gas flame were deposited on the material W. The temperature of the material W to be sprayed was left as it was (room temperature), and the distance between the material W to be sprayed and the center of the spray nozzle 12a of the mist supply nozzle 12 was 109 mm. The film formation speed for the material W to be sprayed (25 cm square) was 50 μm/sec or more.

A secondary electron image of the cross section of the resulting film, including the film thickness direction, was obtained using a Schottky field emission scanning electron microscope (Hitachi High-Tech Corporation, product name: SU7000) with an acceleration voltage of 5 kV.

Figure 9A is a secondary electron image of a cross section, including the thickness direction, of the yttrium oxide coating of Example 2. Figure 9B is a secondary electron image of a cross section, including the thickness direction, of an yttrium oxide coating obtained by a general gas flame spraying method as a comparative example.

The images in Figures 9A and 9B were binarized using software called ImageJ to determine the porosity. The porosity of the yttrium oxide coating in Figure 9A was 1%, which was a very low value compared to the porosity of the yttrium oxide coating in Figure 9B, which was 18%.

The hardness of the cross section including the thickness direction of the coating of Example 2 was measured using a micro Vickers hardness tester (manufactured by Future Tech, product name: ARS9000) under a load of 200 gf, and was found to be 650 HV, which was superior to the hardness of the coating of the comparative example in Figure 9B, which was 450 HV.

In addition, a Schottky field emission scanning electron microscope (manufactured by JEOL, product name: JSM-IT500HR) was used to obtain a secondary electron image and an EBSD mapping image of the cross section including the film thickness direction of Example 2 at an acceleration voltage of 20 kV.

Figure 9C is a secondary electron image of a cross section including the thickness direction of the yttrium oxide coating of Example 2, at a different position from that of Figure 9A, and Figure 9D is an EBSD mapping image of the same. Note that, in order to understand the differences in the crystal phases in more detail with respect to Figure 9D, an original drawing in which the differences in the crystal phases can be identified by color has been submitted as an object submission document at the same time as this application. Please refer to this original drawing as necessary.

In Figure 9D, red indicates areas where a signal was obtained by the EBSD detector (i.e., crystalline), and black indicates areas where the signal was below a certain level (voids, etc.). No amorphous areas were identified in Figure 9D.

From the above, it was confirmed that Example 2 not only suppresses the change to an amorphous state, but also produces a coating that is very dense and has excellent hardness.

The present invention is not limited to the configuration described in the above embodiment, and various modifications are possible.

For example, in the above embodiment, the thermal spray unit 20 has a function as an angle adjustment mechanism that adjusts the angle θ of the central axis C2 of the thermal spray nozzle 21 relative to the central axis C1 of the mist supply nozzle 12, and a function as a position adjustment mechanism that adjusts the radial position of the thermal spray nozzle 21, but is not limited to this. In other words, the position and attitude of the thermal spray nozzle 21 relative to the mist supply nozzle 12 may be fixed. Alternatively, the thermal spray unit 20 may have only one of the functions as the angle adjustment mechanism and the function as the position adjustment mechanism.

In the above embodiment, six thermal spray nozzles 21 were provided, but this is not limited to this, and the number of thermal spray nozzles 21 may be two or more.

In the above embodiment, the multiple thermal spray nozzles 21 were arranged at equal intervals along the circumferential direction centered on the central axis C1 of the mist supply nozzle 12, but this is not limited thereto, and the multiple thermal spray nozzles 21 do not have to be arranged at equal intervals along the circumferential direction centered on the central axis C1 of the mist supply nozzle 12. In order to uniformly heat the mist sprayed from the mist supply nozzle 12, it is desirable that the multiple thermal spray nozzles 21 are arranged at equal intervals along the circumferential direction centered on the central axis C1 of the mist supply nozzle 12.

In the above embodiment, the central axis C2 of the thermal spray nozzle 21 and the central axis C1 of the mist supply nozzle 12 have an intersection point P, but this is not limited to this, and it is sufficient that the frame sprayed from the thermal spray nozzle 21 and the mist sprayed from the mist supply nozzle 12 intersect.

In the above embodiment, the dispersion medium is an organic solvent, but is not limited thereto and may be water, an organic compound such as a liquid monomer, a liquid oligomer, or a liquid polymer, or a mixture of these.

REFERENCE SIGNS LIST 1 Thermal spraying device 2 Spray medium supply means 3 Slurry supply means 4 Combustion gas supply means 5 Hydrogen supply means 10 Mist supply unit 11 Main body casing 11a Spray medium introduction section 11b Slurry introduction section 11c Communication passage 12 Mist supply nozzle (mist supply section)
12a: spray nozzle 13: gas manifold 20, 20A to 20F: thermal spray unit 21: thermal spray nozzle (flame injection section)
Description of the Reference Numerals 21a Combustion gas inlet 21b Injection port 21c Hydrogen inlet 22 Base member 22a Guide groove 23 Support plate 24 Slide block 24a Pin 24b Screw hole 25 Angle adjustment ring 25a Pin 25b Screw hole 26 First shaft 26a Screw portion 27 Second shaft 27a Screw portion 30 Ring member W Material to be sprayed C1 Central axis of mist supply nozzle C2 Central axis of spray nozzle D1 Mist supply direction D2 Flame spray direction

Claims (6)

a tubular mist supply nozzle that turns a dispersion liquid containing fine particles into a mist and sprays it in a mist supply direction;
a plurality of thermal spray nozzles provided separately from the mist supply nozzle , arranged at intervals in a radial direction from the mist supply nozzle , and spraying a flame;
The thermal spray nozzle sprays the flame and heats the mist from the surroundings ;
A thermal spray device in which, when an axis extending from the spray nozzle of the mist supply nozzle in the mist supply direction is defined as the x-axis, the position of the center of the spray nozzle on the x-axis is defined as x [mm] = 0, and the direction in which the mist is sprayed from the spray nozzle is defined as a positive direction on the x-axis, and the position of the center of the injection port of at least one of the multiple thermal spray nozzles is defined as x1 [mm], the relationship -10≦x1≦100 is satisfied . The thermal spraying device according to claim 1 , wherein the thermal spraying nozzle sprays the flame in a flame spraying direction inclined radially inward toward the mist supply direction, thereby heating the mist. The thermal spraying device according to claim 2 , wherein the thermal spraying nozzle is disposed so that a central axis of the thermal spraying nozzle and a central axis of the mist supply nozzle intersect at a point. 4. The thermal spraying device according to claim 3, wherein the multiple thermal spray nozzles are arranged such that an intersection between the central axis of one of the thermal spray nozzles and the central axis of the mist supply nozzle is offset from an intersection between the central axis of another of the thermal spray nozzles and the central axis of the mist supply nozzle in the mist supply direction. 5. The thermal spraying apparatus according to claim 3, further comprising an angle adjustment mechanism for adjusting an angle of the central axis of the thermal spraying nozzle relative to the central axis of the mist supply nozzle . The thermal spraying device according to claim 1 , further comprising a position adjustment mechanism for adjusting a position of the thermal spraying nozzle in the radial direction.

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