JPH0765992A - Plasma fusion spray device - Google Patents

Abstract

PURPOSE:To simplify the configuration of a device and allow fusion spray even though the fusion spray material is not in powder form by applying an attachment to a nozzle part which sprays the material melted by the heat of plasma. CONSTITUTION:A fusion spray material 30 of a sleeve form is secured to a mounting metal piece 31, and this is fitted on a nozzle part 24 of a plasma torch 1. The metal piece 31 is secured to a positive electrode 20 using bolts 32. A plasma jet 4 formed in this nozzle part 24 melts the fusion spray material 30 of sleeve form and produces liquid state particulates. When the material 30 is made in a sleeve form, the area touching the plasma jet 4 increases, and a great quantity of liquid particulates are produced. Fusion spray can be repeated however many times if the material 30 is equipped with a large wall thickness.

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 material on the surface of a solid substrate to form a film.

[0002]

2. Description of the Related Art A plasma spraying apparatus heats and melts a thermal spraying material such as ceramics, metal, or plastic with plasma to form liquid fine particles, and the liquid fine particles are collided with a plasma jet at high speed on the surface of a solid base material ( Thermal spraying) to form a film on the solid substrate. By coating with a solid material, ring resistance, wear resistance, electrical insulation, etc. are improved.

FIG. 5 is a system diagram showing the structure of a conventional plasma spraying apparatus. A plasma torch 1 ejects a plasma jet 4 containing liquid fine particles toward the surface of a solid substrate 2 on which a film is to be formed. Wirings 13A and 1 are connected to the anode terminal 20A and the cathode terminal 22A of the plasma torch 1.
The power supply 18 is electrically connected via 3B. The power source 18 includes a DC power source 18A and a high frequency power source 18B. In addition, the gas spraying unit 15 is connected to the gas cylinder 9 through the pipe 12A.
It is connected to the gas supply port 15A of the plasma torch 1 through a pipe. Further, the powder feeding unit 14 is configured to change the raw material powder 5
Is connected to the powder supply port 14A of the plasma torch 1 through a pipe 12B. A gas cylinder 8 is connected to the pipe 12B.

FIG. 6 is a sectional view showing the structure of the plasma torch 1 of FIG. 5, showing the internal structure thereof. The plasma torch 1 is provided with a cathode 22 having a cathode terminal 22A at the center of its axis. The positive electrode 20 is arranged on the outer periphery of the negative electrode 22 via an insulator 21. The positive electrode 20 is the anode terminal 2
0A is provided, and the nozzle portion 24 is formed.
As described above, the plasma torch 1 has a gas supply port 15A.
Is provided, and the working gas 10 is sprayed onto the tip portion 22B of the negative electrode 22. Further, the plasma torch 1 is provided with a powder supply port 14A, and the raw material powder 5 is introduced into the plasma jet 4.

In FIG. 6, a voltage is applied between the positive electrode 20 and the negative electrode 22 to generate arc plasma at the tip portion 22B of the negative electrode 22. A working gas 10, for example, an argon gas is blown onto this arc plasma, and a plasma jet 4 is ejected in the direction of arrow 25. At that time, the raw material powder 5 is introduced into the plasma jet 4, and the raw material powder 5
Is melted by plasma heat and becomes liquid particles. The plasma jet 4 is ejected from the nozzle 24 together with the liquid particles.

Returning to FIG. 5, the high frequency power source 18B is for an arc trigger for causing the direct current from the direct current power source 18A to flow between the electrodes of the plasma torch 1. High frequency power supply 18
By B, a high voltage is superposed between the electrodes to cause a dielectric breakdown between the electrodes. Since a dielectric breakdown between the electrodes makes them conductive, a large current of tens of volts or thousands of amperes flows between the electrodes even if the voltage of the DC power supply 18A is low, and high-temperature plasma is generated. The gas cylinder 9 is filled with a working gas 10. The gas cylinder 8 is filled with a carrier gas 6, for example, argon gas. The carrier gas 6 is for sending the raw material powder 5 to the powder supply port 14 </ b> A by its wind pressure and for introducing it into the plasma jet 4.

In FIG. 5, a solid body 2 is arranged opposite to a plasma torch 1 with a gap length G interposed therebetween. The plasma jet 4 spreads in the radial direction as it progresses along the gap length G, and forms a circular film 17 having a diameter D in the range 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 tens of thousands of degrees K plasma jet 4 is generated by a DC power source of several thousand amps to spray the alumina powder. For example, if the gap length G is set to several tens of cm, a circular ceramic film 17 having a diameter D of about 10 cm can be formed on the surface of the solid substrate 2. After forming the film 17, the peripheral shape of the film 17 is finished into a desired shape by edging.

[0008]

However, the conventional apparatus as described above has a problem in that the thermal spray material must be made into powder. The thermal spray material was supplied to the nozzle section through the powder charging section. Therefore, it is necessary to process the thermal spray material into a powder form, and the pretreatment requires a long processing time. Further, the powder charging section requires piping, which complicates the structure of the apparatus.

An object of the present invention is to enable thermal spraying without necessarily making the thermal spray material into a powder form and to simplify the structure of the apparatus.

[0010]

In order to achieve the above object, 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 blown onto the plasma are provided. A gas spraying part for forming a plasma jet and a nozzle part for injecting the spraying material melted by the heat of plasma together with the plasma jet, the spraying material is fixed to the nozzle part.

In such a structure, the thermal spray material is formed into a sleeve shape and fitted to the nozzle portion, or the powder thermal spray material is housed between the coaxially arranged double cylinders. The double cylinder is fitted to the nozzle portion, or the spray material is formed in a net shape and fixed to the outlet of the nozzle portion, or the spray material is formed in a wire shape, It shall be fixed to the outlet of the nozzle.

[0012]

By fixing the thermal spray material to the nozzle portion, the thermal spray material can be sprayed even if it is not always in powder form. When the thermal spray material is not powder, for example, it is made into a sleeve shape and fitted into the nozzle portion, or is made into a mesh shape or a wire shape and fixed to the outlet of the nozzle portion. The thermal spray material, even if it is not a powder, is immediately melted into liquid particles by the heat of the sprayed plasma jet.

When the thermal spray material is powder, for example, coaxial 2
The powder is stored between the heavy cylinders, and the double cylinder is fitted to the nozzle portion. If the inner cylinder is formed of a thin film, the inner cylinder is immediately broken by the heat of the plasma jet. This causes the powder to come into contact with the plasma jet and the thermal spray material to become liquid particulate. In addition, since the thermal spray material is directly fixed to the nozzle portion, the powder feeding portion, which is required in the conventional apparatus, becomes unnecessary, and the configuration of the apparatus is simplified.

[0014]

EXAMPLES The present invention will be described below based on examples.
FIG. 1 is a cross-sectional view of essential parts showing the structure of a plasma spraying apparatus according to an embodiment of the present invention. Sleeve-shaped thermal spray material 30
Is fixed to the mounting member 31 and fitted into the nozzle portion 24 of the plasma torch 1. The fitting 31 is fixed to the positive electrode 20 via a bolt 32. Others are the same as the conventional configuration of FIG. The same parts are designated by the same reference numerals, and detailed description thereof is omitted.

In FIG. 1, the plasma jet 4 formed in the nozzle portion 24 melts the sleeve-shaped spray material 30 to generate liquid fine particles. In addition, thermal spray material 3
The shape of 0 does not necessarily have to be a cylindrical shape like a sleeve as long as there is a hollow portion from which the plasma jet 4 blows.
The thermal spray material 30 may have any shape as long as it is fixed to the inner peripheral surface of the nozzle portion 24. Since the thermal spray material 30 is formed in a sleeve shape, the area in contact with the plasma jet 4 is increased and a large amount of liquid fine particles are generated. Also,
By increasing the wall thickness of the thermal spray material 30, the thermal spray can be performed many times.

FIG. 2 is a sectional view showing the structure of a plasma spraying apparatus according to another embodiment of the present invention. Cylinder 34,
35 coaxially forms a double cylinder, and the powder-form thermal spray material 33 is filled between them. The cylinder 34 is formed of a thin film, and both ends thereof are sealed so that the powdery thermal spray material 33 inside does not come out. The cylinder 35 is fixed to the positive electrode 20 via a bolt 32. Other configurations are the same as those in FIG.

In FIG. 2, the plasma jet 4 formed in the nozzle portion 24 instantly melts the thin film cylinder 34 and contacts the powder-form thermal spray material 33. As a result, liquid fine particles are generated and ejected from the nozzle portion 24.
The cylinder 34 does not necessarily have to be cylindrical. This is the same as that described in FIG. 1, and the cylinder 34 may be immediately melted by the plasma jet 4.

FIG. 3 is a sectional view showing the structure of a plasma spraying apparatus according to a further different embodiment of the present invention. A reticulated thermal spray material 36 is fixed to the positive electrode 20 via a bolt 32 at the outlet of the nozzle portion 24. Others are the same as the configuration of FIG. In FIG. 3, the plasma jet 4 formed in the nozzle portion 24 melts the reticulated thermal spray material 36 to generate liquid fine particles. It should be noted that the thermal spray material 36 does not necessarily have to have a mesh shape, and a plate shape having a large number of holes scattered therein can sufficiently function.

FIG. 4 is a sectional view showing the structure of a plasma spraying apparatus according to another embodiment of the present invention. A plurality of wire-shaped sprayed materials 37 are applied to the positive electrode 2 via screws 38.
It is fixed at 0. In FIG. 4, the plasma jet 4 formed in the nozzle portion 24 is a wire-shaped spray material 3
7 is melted to form liquid fine particles. It should be noted that the thermal spray material 36 does not necessarily have to have a wire shape, but may have any shape as long as it has a gap from which the plasma jet 4 blows.

[0020]

As described above, according to the present invention, by fixing the thermal spray material to the nozzle portion, the thermal spray material can be sprayed without necessarily being in powder form. Since it is not necessary to powder all the material to be sprayed, the processing time is greatly reduced. Further, since the powder feeding unit provided with the pipe like the conventional device is unnecessary, the structure of the device is simplified and the equipment cost is saved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing the configuration of a plasma spraying apparatus according to an embodiment of the present invention.

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

FIG. 3 is a cross-sectional view of an essential part showing the configuration of a plasma spraying apparatus according to still another embodiment of the present invention.

FIG. 4 is a cross-sectional view of an essential part showing the configuration of a plasma spraying apparatus according to still another embodiment of the present invention.

FIG. 5 is a system diagram showing the configuration of a conventional plasma spraying apparatus.

6 is a sectional view showing the configuration of the plasma torch of FIG.

[Explanation of symbols]

1: plasma torch, 4: plasma jet, 20: positive electrode, 22: negative electrode, 24: nozzle part, 30, 33, 3
6, 37: Thermal spray material, 31: Mounting bracket, 32: Bolt,
34, 35: cylinder, 38: screw

Claims (5)

[Claims] 1. A pair of electrodes for generating plasma, a power source connected in parallel to the pair of electrodes, a gas spraying unit for spraying a working gas onto the plasma to form a plasma jet, and a thermal spray material melted by the heat of the plasma. A plasma spraying apparatus comprising: a nozzle part for injecting the material together with a plasma jet, wherein a spraying material is fixed to the nozzle part. 2. A plasma spraying apparatus according to claim 1, wherein the spraying material is formed into a sleeve shape and fitted in the nozzle portion. 3. The powder spraying material according to claim 1, wherein the powdery thermal spray material is housed between coaxially arranged double cylinders.
A plasma spraying device, characterized in that a heavy cylinder is fitted in a nozzle portion. 4. The plasma spraying apparatus according to claim 1, wherein the spraying material is formed in a net shape and is fixed to the outlet of the nozzle portion. 5. The plasma spraying apparatus according to claim 1, wherein the spraying material is formed into a wire shape and is fixed to the outlet of the nozzle portion.