JPH04131649U - plasma spray gun - Google Patents

Abstract

(57) [Summary] [Purpose] To efficiently heat the particles of plasma sprayed powder and to uniformize the heating and acceleration of the particles. [Structure] A plasma generation chamber 2 having a plasma jet nozzle 3 at the tip is provided, an anode 1 having an insulator 4 bonded to the base, and an anode 1 which is penetrated on the axis of the insulator 4 and whose tip is inside the plasma generation chamber 2. A cathode 5 and a cathode current introduction part 6 are loosely inserted and have a working gas and thermal spray powder supply passage 7 bored on the axis, and a hole is made near the side of the insulator 4 so that the tip communicates with the plasma generation chamber 2. and an ambient gas passage 8 provided therein.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a plasma spray gun.

0002

[Conventional technology]

Plasma generated by passing an electric current between the anode and cathode is ejected as a jet. At the same time, spray powder is supplied to the same jet to form a spray coating on the surface of the workpiece. As a conventional plasma spray gun, the one shown in the vertical cross-sectional view of Figure 2 is a typical one. It has been known. In other words, in FIG. 2, there is plasma on the axis of the copper anode 21. A generation chamber 22 is provided, and a plasma jet nozzle 23 is opened at the tip thereof. An insulator 24 is fixed to the base side of the anode 21. this insulator On the axis of 24, there is a cathode current introducing section 2 with a tungsten cathode 25 attached to the tip. 6 is provided through the plasma generation chamber 22, and the cathode 25 is inserted into the plasma generation chamber 22.

0003 Also, near the side of the insulator 24, the tip is attached to the base of the plasma generation chamber 22. A working gas supply passage 27 is bored so as to communicate with the anode 21. The tip is almost near the plasma jet nozzle 23 of the plasma generation chamber 2. A thermal spray powder supply path 28 is bored so as to communicate at right angles. Furthermore, the anode 21 is A cooling water passage 29 is bored, and its cooling water inlet is formed in the anode current introduction part 30. A cooling water passage 31 communicating with the cooling water passage 29 is also provided in the cathode current introducing portion 26. has been done.

When performing plasma spraying using such a plasma spray gun, first, cooling water is flowed through the cooling water passages 29 and 31 in order to cool the anode 21 and the cathode 25, and the plasma generation chamber is supplied from the working gas supply passage 27. A working gas such as Ar gas, He 2 gas, N ₂ gas, or a mixture thereof is supplied to 22 . Next, a positive voltage is applied to the anode 21 and a negative voltage is applied to the cathode 25 from a DC power source, and then a high frequency voltage is applied between the anode 21 and the cathode 25 from a high frequency power source to generate a spark discharge between the electrodes 21 and 25. generate.

[0005] This spark discharge causes a positive voltage to be generated by the applied voltage from the DC power supply that was previously applied. Plasma is generated between the pole 21 and the cathode 25, and the plasma generation chamber 22 contains Filled with high-temperature plasma, a high-temperature and high-speed plasma jet is emitted from the plasma jet nozzle 23. It erupts as a cut. At this time, the current was gradually increased to stabilize the plasma jet. Afterwards, the thermal spray powder is supplied from the thermal spray powder supply path 28 to the plasma jet generation chamber 2. 2 near the plasma jet nozzle 23. supplied to the plasma jet Thermal spray powder particles are heated and accelerated and ejected together with a high-temperature, high-speed plasma jet. do.

[0006] However, in such plasma spray guns, the supply of thermal spray powder is difficult. Because it is near the plasma jet nozzle 23 and almost perpendicular to the ejection direction, the supply In addition to the inefficiency of heating the sprayed powder particles, the particles are heated and accelerated uniformly. There are many particles with low energy in the plasma jet due to insufficient temperature rise and acceleration. Therefore, the density, strength and adhesion of the sprayed coating are reduced.

[0007]

[Problem that the idea aims to solve]

The present invention was proposed in view of these circumstances, and it is carried out efficiently, the heating and acceleration of particles are made uniform, and plasma generation is improved. Plasma spray gas that stabilizes the raw material and allows you to obtain high quality thermal spray coatings. The purpose is to provide the following information.

[0008]

[Means to solve the problem]

To this end, the present invention has developed a plasma generation chamber with a plasma jet nozzle at the tip. An anode with an insulator bonded to the base and a shaft of the insulator. The tip is inserted into the plasma generation chamber and the axis line is inserted through the plasma generation chamber. A cathode with working gas and thermal spray powder supply passages perforated above, and a cathode near the side of the above insulator. and a surrounding gas passage bored so that its tip leads to the plasma generation chamber. It is characterized by the following.

[0009]

[Effect]

With the above configuration, the particles of thermal spray powder can be heated efficiently and the particles can be heated. Heating and acceleration are made uniform, plasma generation is stabilized, and high quality is achieved. A plasma spray gun capable of producing a sprayed coating can be obtained.

0010

【Example】

An embodiment of the plasma spray gun of the present invention is explained with reference to FIG. 1, which is a vertical cross-sectional view. A plasma generation chamber 2 is provided on the axis of the anode 1, and a plasma is placed at the tip of the chamber 2. A Mudget nozzle 3 is opened, and an insulator 4 is fixed to the base side of the anode 1. It is. A tungsten cathode 5 is attached to the tip of the insulator 4 on its axis. A cathode current introduction part 6 is provided through the cathode 5 so that the cathode 5 is loosely inserted into the plasma generation chamber 2. At the same time, working gas and thermal spray powder supply are provided on the axis of the cathode 5 and the cathode current introduction part 6. A feed passage 7 is bored.

[0011] Also, near the side of the insulator 4, the tip is connected to the plasma generation chamber 2. An ambient gas passage 8 is bored in the area. Furthermore, a cooling water passage 9 is bored in the anode 1. , the cooling water inlet part is formed in the anode current introduction part 10 and the cathode current introduction part 6. A cooling water passage 11 is also provided.

0012 When performing plasma spraying with such a plasma spray gun, the first step is to In order to cool the electrode 1 and the cathode 5, cooling water is allowed to flow through the cooling water passages 9 and 11, and From the working gas and thermal spray powder supply path 7 to the plasma generation chamber 2, for example, an Ar gas Flow the working gas at a flow rate of 25 l/min. Next, from the DC power supply, the positive electrode is connected to the anode 1, and the negative electrode is connected to the negative electrode 5. A negative applied voltage is applied, and then a high frequency voltage is applied between the anode 1 and the cathode 5 from a high frequency power source. is applied to generate a spark discharge between both electrodes 1 and 5.

[0013] Due to this spark discharge, plasma is generated between the anode 1 and the cathode 5 due to the applied voltage from the DC power source that was previously applied, and the plasma generation chamber 2 is filled with high-temperature plasma, and the plasma jet nozzle is 3, it is ejected as a high-temperature, high-velocity plasma jet. At this time, the current is gradually increased to, for example, 700 A, and then, for example, 1.5 l/min of H ₂ gas is flowed from the surrounding gas passage 8, so that the current and voltage become 700 A and 38 V, and the plasma jet becomes stable.

After the plasma jet has stabilized, thermal spray powder, such as Al ₂ O ₃ powder with a particle size distribution of 10 to 40 μm, is transferred from the working gas and thermal spray powder supply path 7 to the plasma generation chamber 2 at a rate of Ar gas of 5 l/min. is supplied as a carrier gas at a flow rate of 20 g/min. The particles of the thermal spray powder supplied to the plasma are rapidly heated and accelerated, and are ejected together with a high-temperature, high-velocity plasma jet. At this time, the sprayed powder supplied to the plasma is supplied in the same direction as the ejection direction of the plasma jet, so the particles are heated and accelerated uniformly, resulting in a high-quality sprayed coating with sufficient density, strength, and adhesion. is formed. Furthermore, since the thermal spray powder is supplied to the center of the plasma, heating efficiency is high. Furthermore, by the H ₂ gas supplied from the surrounding gas passage 8, an arc point is formed at a distance between the anode 1 and the cathode 5, and the plasma is stabilized, and the cathode 5 is cooled by the H ₂ gas, extending its life. Become. Since the H ₂ gas brings the thermal spray powder to the center of the plasma, it is possible to prevent the thermal spray powder from adhering to the inner peripheral surface of the anode 1 and obstructing the flow of the plasma jet.

[0015]

[Effect of the idea]

In short, according to the present invention, a plasma generator with a plasma jet nozzle at the tip An anode provided with a chamber and an insulator bonded to the base, and the insulator The plasma generator is installed on the axis of the plasma generating chamber, and its tip is loosely inserted into the plasma generation chamber. A cathode with working gas and thermal spray powder supply passages drilled on the axis, and a side portion of the insulator. a peripheral gas passage bored so that its tip leads to the plasma generation chamber; With this, the particles of thermal spray powder are heated efficiently and the particles are The heating and acceleration of the plasma are made uniform, and the generation of plasma is stabilized, resulting in high quality This invention is industrially superior because it provides a plasma spray gun that can obtain a sprayed coating of It is extremely useful.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the plasma spray gun of the present invention.

FIG. 2 is a longitudinal cross-sectional view of a conventional plasma spray gun.

[Explanation of symbols]

1 Anode 2 Plasma generation chamber 3 Plasma jet nozzle 4 Insulator 5 Cathode 6 Cathode current introduction section 7 Working gas and thermal spray powder supply path 8 Surrounding gas passage 9 Cooling water passage 10 Anode current introduction section 11 Cooling water passage

Claims (1)

[Scope of utility model registration request] 1. An anode comprising: a plasma generation chamber having a plasma jet nozzle at its tip; an anode having an insulator bonded to its base; a cathode having a working gas and thermal spray powder supply passage bored along its axis; and a peripheral gas passage bored near the side of the insulator so that its tip communicates with the plasma generation chamber. A plasma spray gun characterized by: