JP3028709B2 - 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, and the liquid fine particles are rapidly applied to the surface of a solid base material by a plasma jet. 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. 3 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. Wirings 13A, 1A are connected to the anode terminal 20A and the cathode terminal 22A of the plasma cheat 1.
The pulse power supply 11 is electrically connected via 3B. Further, a gas spraying section 15 is connected to the gas supply port 15A of the plasma torch 1 from the gas cylinder 9 via a pipe 12A. Further, a powder charging section 14 is connected to the powder supply port 14A of the plasma torch 1 from the powder container 7 containing the raw material powder 5 via a pipe 12B. The gas cylinder 8 is connected to the pipe 12B.

FIG. 4 is a sectional view showing the structure of the plasma torch 1 of FIG. The plasma torch 1 has a negative electrode 22 provided with a cathode terminal 22A around 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 a nozzle part 24. As described above, the plasma torch 1 is provided with the gas supply port 15A,
0 is sprayed on the tip 22B of the negative electrode 22. The plasma torch 1 is provided with a powder supply port 14A, and the raw material powder 5 is injected into the plasma jet 4.

In FIG. 4, 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 nozzle unit 24 to the outside together with the liquid fine particles.

Returning to FIG. 3, the pulse power supply 11 causes dielectric breakdown between the electrodes of the plasma jet 4 and generates a high-temperature plasma by flowing a large current between the electrodes. 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 supplied with the raw material powder 5 by the wind pressure.
Is supplied to the powder supply port 14A and injected into the plasma jet 4.

In FIG. 3, a solid body 2 is arranged to face a plasma torch 1 with a gap length G therebetween. The plasma jet 4 travels along the gap length G and expands in the radial direction, forming a circular coating 3 having a diameter D on the surface of the solid substrate 2. When alumina powder having a melting temperature of 2300 ° K is used as the raw material powder 5, a plasma jet 4 of tens of thousands of K is generated, and the alumina powder is sprayed on a solid body.

In the apparatus shown in FIG. 3, a pulse power supply 11 is used as a current source, and a gap length G is about 1 cm. 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 thickness of the film 3 becomes uneven at some places. Film 3
The center portion of the film 3 rises considerably thickly, and the film 3 is formed thinner toward the peripheral portion. If the gap length G is reduced to about 1 cm, the thickness of the film 3 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. Accordingly, a patent application has already been filed by the same applicant for a method of using a pulse power supply 11 as a current source and injecting the plasma jet 4 only for a very short time to suppress a rise in the temperature of the solid substrate 2 itself. A uniform and thin (thickness of several μm) film 3 is formed by plasma spraying using the pulse power supply 11, and the adhesion to the solid substrate 2 is far superior to that of a DC power supply. The coating 3 is obtained.

[0009]

However, the conventional apparatus as described above has a problem that the area of a film formed by one plasma spraying is small. That is,
As described above, by setting the gap length G to about 1 cm and applying a pulse voltage, an excellent film can be formed. However, the diameter of the film formed by one plasma spraying was almost equal to the gap length G, and was about 1 cm. Conventionally, when it is desired to form a coating having a large area, plasma spraying has been performed many times while shifting the position of the solid substrate. Therefore, a large amount of time was required for plasma spraying.

An object of the present invention is to increase the area of a film formed by one plasma spraying.

[0011]

According to the present invention, an electrode pair for generating plasma, a power supply connected in parallel to the electrode pair, and a working gas are supplied to the plasma. In a plasma spraying apparatus comprising a gas blowing unit for forming a sprayed plasma jet, a powder charging unit for charging the raw material powder into the plasma jet, and a nozzle unit for discharging the raw material powder melted by plasma heat together with the plasma jet. A pulse power source that outputs a voltage in a pulsed manner is used as the power source, and the nozzle unit has a plurality of injection holes on the plasma jet emission side.

In this configuration, it is assumed that the powder inputting section can input individual raw material powders into the plasma jets in the respective injection holes.

[0013]

According to the structure of the present invention, the nozzle portion has a plurality of injection holes on the plasma jet emission side. A plurality of coatings are respectively formed at different positions on the solid substrate by the plasma jets emitted from the injection holes.
This increases the area of the film formed by one plasma spray.

In this configuration, the powder input section is configured so that individual raw material powders can be input into the plasma jets of the respective injection holes. Thereby, the patterns of the coatings made of different materials can be formed by one plasma spraying.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
FIG. 1 is a sectional view of a main part showing a configuration of a plasma spraying apparatus according to an embodiment of the present invention. The nozzle part 24 of the plasma torch 1 branches into a plurality of injection holes 24A and 24B on the emission side of the plasma jet 4. The rest is the same as the conventional configuration of FIG. The detailed description is omitted by using the same reference numerals for the same parts.

The apparatus shown in FIG. 1 uses a plasma jet spray 4 mixed with a raw material powder 5 by one plasma jet spraying.
Are diverted to form a plurality of coatings 3 on the solid substrate 2. If the separation positions of the injection holes 24A and 24B are appropriately arranged, the plasma jet 4 spreads, so that the plurality of coatings 3 can be formed so as to be connected to each other.
This makes it possible to increase the area of the coating 3 several times as compared with the conventional apparatus. FIG. 1 shows two injection holes 2.
Although only 4A and 24B are shown, the area of the coating 3 can be greatly increased by arranging a large number of injection holes toward the solid substrate 2.

FIG. 2 is a sectional view showing a main part of a configuration of a plasma spraying apparatus according to another embodiment of the present invention. Powder supply ports 25A, 25B are provided in each of injection holes 24A, 24B, and powder supply ports 25A, 25B are provided.
Raw material powders 5A and 5B can be individually supplied to B. The rest is the same as the configuration of FIG. In the apparatus shown in FIG. 2, if the raw material powders 5A and 5B are made of different materials, the coating 3
A and 3B are formed of materials different from each other. Therefore, different coating patterns can be formed by one plasma spraying. FIG. 2 shows an apparatus for forming two types of films by one plasma spraying. However, by providing a large number of injection holes, it is possible to form films having a large area and various patterns. it can.

[0018]

According to the present invention, as described above, the nozzle portion has a plurality of injection holes on the plasma jet emission side. Thereby, the required number of times of plasma spraying was reduced, and the time required for plasma spraying was greatly reduced. Further, in such a configuration, individual raw material powders can be charged into each injection hole. This makes it possible to form the patterns of the coating films made of different materials with a small number of times of plasma spraying.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of a main part showing a configuration of a plasma spraying apparatus according to another embodiment of the present invention.

FIG. 3 is a system diagram showing a configuration of a conventional plasma spraying apparatus.

FIG. 4 is a sectional view showing the configuration of the plasma torch of FIG. 3;

[Explanation of symbols]

1: plasma torch, 4: plasma jet, 20: positive electrode, 22: negative electrode, 24: nozzle part, 24A, 24
B: injection hole, 14A, 25A, 25B: powder supply port,
5, 5A, 5B: raw material powder, 3, 3A, 3B: coating,
2: Solid body

Claims (2)

(57) [Claims] 1. A pair of electrodes for generating plasma, a power supply connected in parallel to the pair of electrodes, a gas blowing unit for blowing a working gas to the plasma to form a plasma jet, and charging raw material powder to the plasma jet. In a plasma spraying apparatus including a powder input unit and a nozzle unit for injecting raw material powder melted by plasma heat together with a plasma jet, a pulse power supply that outputs a pulsed voltage as the power supply is used, and the nozzle unit is A plasma spraying apparatus comprising a plurality of injection holes on an injection side of a plasma jet. 2. The plasma spraying apparatus according to claim 1, wherein the powder injection section is capable of inputting individual raw material powders into the plasma jets in the respective injection holes.