JP3144184B2 - Plasma spraying equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for spraying a molten powder onto a surface of a solid substrate to form a film.

[0002]

2. Description of the Related Art A plasma spraying apparatus heats and melts a powdery ceramic material, a metal, a plastic, or the like with plasma to form liquid fine particles. This is for causing a collision (spraying) to form a film on a solid substrate. The ring resistance, wear resistance, electrical insulation, etc. are improved by coating the solid substrate.

FIG. 7 is a system diagram showing a configuration of a conventional plasma spraying apparatus. The plasma torch 1 injects a plasma jet 4 containing liquid fine particles toward the surface of the solid substrate 2 on which a film is to be formed. A pulse power supply 18 is connected to an anode terminal 20A and a cathode terminal 22A of the plasma torch 1 via a wiring 13. In addition, a gas blowing unit 15 is connected to a gas blowing port 15A provided in the plasma torch 1 from the gas cylinder 9 via a pipe 12A. Further, the powder input unit 14 is connected to the plasma torch 1 via the pipe 12B from the powder container 7 containing the raw material powder 5.
Is connected to the powder input port 14A provided in the pipe.
The gas cylinder 8 is connected to the pipe 12B.

FIG. 8 is a sectional view showing the internal structure of the plasma torch 1 of FIG. The plasma torch 1 is provided with a negative electrode 22 having a cathode terminal 22A at the center of the axis.
The positive electrode 20 is arranged on the outer periphery of the negative electrode 22 with an insulator 21 interposed therebetween. The positive electrode 20 has an anode terminal 20 </ b> A and forms an injection hole 24. As described above, the plasma torch 1 is provided with the gas blowing port 15 </ b> A, and the working gas 10 is blown to the tip 22 </ b> B of the negative electrode 22. The plasma torch 1 is provided with a powder inlet 14A, and the raw material powder 5 is injected into the plasma jet 4.

In FIG. 8, a voltage is applied between the positive electrode 20 and the negative electrode 22 to generate a plasma arc at the tip 22 B of the negative electrode 22. A working gas 10, for example, an argon gas is blown onto the plasma arc, and a plasma jet 4 is ejected in the direction of arrow 25. At this time, the raw material powder 5 is injected into the plasma jet 4 and the raw material powder 5
Are melted by plasma heat to become liquid fine particles. The plasma jet 4 is ejected from the ejection hole 24 to the outside together with the liquid fine particles.

Returning to FIG. 7, the insulation between the electrodes of the pulse power supply 18 is caused, and a large current is applied between the electrodes to generate high-temperature plasma. The gas cylinder 9 is filled with a working gas 10. The gas cylinder 8 is filled with a carrier gas 6, for example, an argon gas. The carrier gas 6 is for sending the raw material powder 5 to the powder input port 14A by the wind pressure and for inputting it into the plasma jet 4.

In FIG. 7, a solid substrate 2 is arranged to face a plasma torch 1 with a gap length G therebetween. The plasma jet 4 spreads in the radial direction as it progresses along the gap length G, and forms a circular spray coating 17 having a diameter D in the surface of the solid substrate 2. When, for example, alumina powder having a melting temperature of 2300 ° K is used as the raw material powder 5, a plasma jet 4 at tens of thousands of degrees K is generated, and the alumina powder is sprayed onto the solid substrate 2.

In the apparatus shown in FIG. 7, a pulse power supply 18 is used as a current source, and a gap length G is several cm.
It is about. As an example of a different conventional device, there is a device in which a current source is a DC power supply and a gap length G is about 10 cm. However, if the gap length G is too large, the thin sprayed coating 17 having a thickness of several μm cannot be formed uniformly, and it may become non-uniform depending on the location. Thermal spray coating 1
The central part of 7 rises to a thickness of several hundred μm. If the gap length G is reduced to several centimeters or less, a thin sprayed coating 17 is formed uniformly. If the gap length G is reduced, the solid substrate 2 itself may be damaged by the heat of the plasma jet 4. Therefore, the current source is changed to the pulse power supply 18.
A method of suppressing the temperature rise of the solid body 2 itself by injecting the plasma jet 4 only for a very short time has already been applied for a patent by the same applicant. By plasma spraying using the pulse power supply 18, the thickness is uniform,
In addition to forming a thin (several μm thick) thermal spray coating 17, the thermal spray coating 17 having much better adhesion to the solid substrate 2 than that obtained by a DC power supply is obtained.

[0009]

However, the conventional apparatus as described above has a problem that the area of the thermal spray coating formed on the solid substrate is small. That is, since the gap length G needs to be about several cm or less, the spread of the plasma jet is inevitably small.
A thermal spray coating having a diameter of several cm or more cannot be formed by multiple thermal sprays. If you want to obtain a large area spray coating,
In the past, plasma spraying was performed many times by changing the position of the plasma torch. For this reason, the total time of film formation by plasma spraying becomes large, and an apparatus capable of forming a large area in a short time has been desired.

An object of the present invention is to provide an apparatus capable of forming a large area in a short time.

[0011]

According to the present invention, there is provided an electrode pair for generating plasma, a power source connected to the electrode pair, and a plasma jet for blowing a working gas onto the plasma. In a plasma spraying apparatus provided with a gas spraying part to be formed, a powder feeding part for feeding a raw material powder into a plasma jet, and a plasma spraying part constituted by an injection hole for injecting the raw material powder melted by plasma heat together with the plasma jet. Preferably, a pulse power supply for outputting a pulse voltage is used as the power supply, and a plurality of the plasma spraying units are arranged.

In this configuration, it is preferable that the injection holes of the respective plasma spraying portions have different diameters. Further, in such a configuration, it is preferable that the ejection holes of the respective plasma spraying portions eject the plasma jet in directions different from each other. Further, in such a configuration, it is preferable that the power supply of each plasma spraying unit outputs a pulse voltage at different times.

[0013]

According to the structure of the present invention, by arranging a plurality of plasma spraying portions, the ranges formed by the respective plasma spraying portions can be overlapped with each other by a single plasma spraying. As a result, a sprayed coating having a large area can be formed in a short time.

Further, in such a configuration, the injection holes of the respective plasma sprayed portions have different diameters. As a result, the portions of the sprayed coating that overlap each other can be made as small as possible, and a sprayed coating having a more uniform thickness can be formed. Further, in such a configuration, the ejection holes of the respective plasma spraying portions eject the plasma jet in directions different from each other. Thereby, it is easy to easily overlap the film formation range of the adjacent plasma sprayed portion, and it is easy to fill the gap between the films.

Further, in such a configuration, the power supply of each plasma spraying section outputs a pulse voltage at different times. Accordingly, the plasma jet can be ejected at different times from each other, so that the film can be simultaneously formed even if the surface on which the film is formed has irregularities or steps depending on the location.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a side view showing a configuration of a plasma spraying apparatus according to an embodiment of the present invention. The three plasma spraying parts 3 are arranged side by side, and the solid substrate 2 on which the film is formed is arranged on the injection hole 24 side. A thermal spray coating 170 is formed on the solid substrate 2 by the plasma jet 4 emitted from the injection hole 24. Each plasma spraying section 3 in FIG. 1 corresponds to the entire plasma spraying apparatus in FIG. 7, and this is represented only by a plasma torch. Therefore, each plasma spraying section 3 is provided with a pulse power supply, a gas spraying section, and a powder charging section in addition to the plasma torch, which are the same as those in FIG.

In FIG. 1, if the plasma spraying sections 3 are properly arranged, the plasma jets 4 can overlap each other on the solid substrate 2 and are uniform and wide (the film forming range by one plasma spraying section). (About three times). Further, by arranging three or more, generally a plurality of, plasma sprayed portions 3, it is possible to form a wider sprayed coating.

FIG. 2 is a side view showing a configuration of a plasma spraying apparatus according to another embodiment of the present invention. This figure is a view as seen from the injection hole side of the plasma torch, and includes four plasma spray portions 3 and a plasma spray portion 30 having an injection hole 26 having a smaller diameter than the injection hole 24 of the plasma spray portion 3. Are arranged side by side. In FIG. 2 as well, the plasma spraying sections 3 and 30 are represented only by a plasma torch as in FIG.

FIG. 3 is a side view showing the range of the thermal spray coating formed on the solid substrate by the apparatus shown in FIG. Film 1
Numerals 7 and 11 are formed by the plasma spray portions 3 and 30, respectively. In FIG. 3, the positions where the injection holes 24 and 26 are arranged are indicated by dotted lines. As can be seen from FIG. 3, the thermal spray coatings 11 and 17 overlap each other,
The gap where no film is formed is filled. Injection hole 26
Is an eye smaller than the surrounding injection hole 24. If the injection hole 26 is enlarged and the same one as the injection hole 24 is used, no gap is formed in the film formation, but the area of the film portion 16 formed by three plasma sprayed portions to overlap three layers is reduced. Increase. As a result, the entire thermal spray coating is not uniformly finished, and concavities and convexities are conspicuous. By appropriately setting the diameter of the injection hole 26, it is possible to minimize a portion that overlaps in multiple layers such as the coating 16.

FIG. 4 is a side view showing a configuration of a plasma spraying apparatus according to still another embodiment of the present invention. Injection holes 27 for plasma spraying portions 31 on both sides to inject plasma jet 41 obliquely toward the center of solid substrate 34
And the thermal spray coating 28 is formed. Others are shown in Figure 1
The configuration is the same as FIG. 5 shows the plasma sprayed part 3 of FIG.
FIG. 2 is a cross-sectional view showing an internal configuration of a plasma torch provided in 1. Injection hole 27 for ejecting plasma jet 41
Are formed diagonally in the direction of arrow 29. The rest is the same as the configuration of the conventional device in FIG.

The solid base 34 shown in FIG.
And the gap G ₁ apart from, the plasma jet 4,4
1 are arranged at positions overlapping each other. FIG.
In, when distributing the solid green body 2 to position 2A of the gap G ₁ (dotted line), it occurs portions plasma jet 4 does not overlap. In such a case, by forming the injection hole 27 obliquely, it is possible to easily obtain the thermal spray coating 28 having no gap as shown in FIG.

FIG. 6 is a side view showing a configuration of a plasma spraying apparatus according to still another embodiment of the present invention. Solid base 33 having step 33A in plasma spraying sections 3 and 32
Are arranged facing each other. The lower half of the solid body 33 is separated from the plasma sprayed portion 32 by a gap G + ΔG. The rest is the same as the configuration of FIG. In FIG.
The plasma jet 40 from the plasma spray unit 32 is generated earlier in time than the plasma jet 4 from the plasma spray unit 3. That is, the plasma spraying section 32 outputs the pulse voltage earlier. By setting the gap ΔG to be equal to the time when the plasma jet 40 advances, the entire thermal spray coating 36 can be simultaneously formed on the solid substrate 33. If the thermal spray coating 36 is partially formed at different times, the film near the step 33A is not uniformly formed.
The thermal spray coating 36 becomes uneven.

In FIG. 6, even if the solid substrate 33 has several steps or irregularities, the solid substrate 33 can be simultaneously placed on the solid substrate by adjusting the time difference of the pulse voltage output from the power supply of the plasma spraying section. A film can be formed, and a uniform sprayed film can be obtained.

[0024]

As described above, according to the present invention, a plurality of plasma sprayed portions are arranged side by side so that a sprayed film having a large area can be formed in a short time. Total time has been significantly reduced.
Further, in such a configuration, the injection holes of the respective plasma sprayed portions have different diameters, so that a sprayed coating having a uniform thickness can be obtained.

Further, in such a configuration, the ejection holes of the respective plasma spraying portions eject the plasma jet in directions different from each other. Thereby, the thermal spray coating can be easily overlapped. Furthermore, in such a configuration, the power supply of each plasma spraying unit outputs a pulse voltage at different times from each other. As a result, even if there is a step or unevenness on the side on which the film is formed, the sprayed film can be formed evenly.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a plasma spraying apparatus according to an embodiment of the present invention.

FIG. 2 is a side view showing a configuration of a plasma spraying apparatus according to another embodiment of the present invention.

FIG. 3 is a side view of a sprayed coating formed by the apparatus of FIG. 2;

FIG. 4 is a side view showing a configuration of a plasma spraying apparatus according to still another embodiment of the present invention.

FIG. 5 is a sectional view showing an internal configuration of a plasma torch of the plasma spraying unit in FIG. 4;

FIG. 6 is a side view showing a configuration of a plasma spraying apparatus according to still another embodiment of the present invention.

FIG. 7 is a system diagram showing a configuration of a conventional plasma spraying apparatus.

FIG. 8 is a sectional view showing the internal configuration of the plasma torch of FIG. 7;

[Explanation of symbols]

35: plasma torch, 2, 33, 34: solid substrate,
4, 40, 41: plasma jet, 5: raw material powder,
6: Carrier gas, 7: Powder container, 8, 9: Gas cylinder, 10: Working gas, 12A, 12B: Piping, 13: Wiring, 14: Powder input section, 14A: Powder input port, 15: Gas spray section, 15 : Gas outlet, 17, 170, 11, 2
8, 36: thermal spray coating, 20: positive electrode, 20A: anode terminal, 21: insulator, 22: negative electrode, 22A: cathode terminal,
22B: Tip, 24, 26, 27: Injection hole, 3, 3
0, 31, 32: plasma sprayed part, 33A: step, 1
6: film part

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05H 1/44 H05H 1/42 C23C 4/12

Claims (4)

(57) [Claims] An electrode pair for generating plasma, a power supply connected to the electrode pair, a gas blowing unit for blowing a working gas to the plasma to form a plasma jet, and a powder inputting unit for inputting raw material powder to the plasma jet And, in a plasma spraying apparatus provided with a plasma spraying unit constituted by an injection hole for injecting a raw material powder melted by plasma heat together with a plasma jet, a pulse power source that outputs a pulse voltage is used as the power source,
A plasma spraying apparatus, wherein a plurality of the plasma spraying units are arranged. 2. The plasma spraying apparatus according to claim 1, wherein the injection holes of each plasma spraying section have different diameters. 3. The plasma spraying apparatus according to claim 1, wherein the injection holes of each plasma spraying section cause the plasma jets to be emitted in different directions. 4. The plasma spraying apparatus according to claim 1, wherein the power supply of each plasma spraying section outputs a pulse voltage at different times.