JP2809359B2 - Thermal spray composite film forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a sprayed composite film.

[0002]

2. Description of the Related Art A schematic view of a conventional plasma spraying method is shown in FIG. 3. A plasma spraying gun for performing spraying on a surface 21a of an object to be sprayed 21 is an anode nozzle 22 cooled by a cooling water passage 22a. And a cathode 23 fixed to the base of the nozzle 22 via an insulator 24. A sprayed powder material supply port 25 is formed at the front of the anode nozzle 22 to form a material supply port 26. A working gas supply port 27 is open at the rear, and a DC power supply 28 and a high frequency generator 29 are connected in parallel between the anode nozzle 22 and the cathode 23.

In order to perform plasma spraying, first, Ar gas is supplied as a working gas from the working gas supply port 27 into the anode nozzle 22, and a direct current power supply 28 is turned on so that no air is supplied between the anode nozzle 22 and the cathode 23. A load voltage is applied, and the high frequency generator 29 is turned on to turn on the anode nozzle 22 and the cathode 23.
When an arc discharge is generated during this time, a continuous arc is generated by the electric power from the DC power supply 28, the working gas becomes a plasma gas, and a high-temperature plasma jet 30 is ejected from the anode nozzle 22. Then, the sprayed powder material supplied from the material supply device (not shown) into the anode nozzle 22 through the sprayed powder material supply port 25 from the material supply port 26 by the Ar gas is heated and accelerated by the plasma jet 30, and the high temperature and high speed are supplied. As the spray particles 31, the particles fly toward the surface 21 a of the object to be sprayed.
collides with and adheres to a to form a thermal spray coating.

[0004] However, as shown in the sectional view of FIG. 4, the state of formation of the thermal spray coating by such a method is that the thermal spray particles 31 that have flown collide against the surface 21a of the thermal spray target and become flat, and the flat particles are deposited. The thermal spray coating 32 is formed, and the flattened thermal spray particles 31 overlap each other to form voids 3 at the boundaries between the particles.
3 is formed, and becomes a porous film as a whole. Therefore, even when such a thermal spray coating 32 is excellent in abrasion resistance and heat insulating properties, when applied as a corrosion resistant film, corrosive substances penetrate into the porous film and cause corrosion of the base material of the thermal spray target 21. . In addition, the presence of the voids 33 at the boundaries between the particles causes a small number of contact portions between the particles, resulting in a small adhesion force, and the peeling may start from the voids 33 and propagate to the surrounding healthy portions.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of such circumstances, and the object to be sprayed is shielded from corroded substances by the dense film structure as a whole, and is not corroded. It is another object of the present invention to provide a method for forming a thermal spray composite film which does not cause thermal spray peeling and has sufficient wear resistance and heat insulating properties.

[0006]

In order to achieve the object, the present invention provides a method for supplying a thermal spray powder material into a high-frequency induction plasma and spraying the material to be sprayed on a particle size distribution which is evaporated by the calorific value of the high-frequency induction plasma as the thermal spray powder material. And simultaneously spraying the sprayed powder material having a particle size distribution that is melted by the calorific value of the high frequency induction plasma into the high frequency plasma to form a sprayed composite film comprising ultrafine particles and sprayed coating particles on the surface of the object to be sprayed. It is characterized by being formed.

[0007]

According to the method for forming a sprayed composite film of the present invention, the sprayed powder material evaporated by the heat of the high frequency induction plasma is cooled near the object to be sprayed to form ultrafine particles, and the sprayed powder material melted by the heat of the high frequency induction plasma. Form thermal spray coating particles with voids between them, and at this time, ultrafine particles are deposited in the voids at the boundaries between the thermal spray coating particles, resulting in a composite film having a dense film structure as a whole. This composite film blocks the corroded material from the object to be sprayed, so that the object to be sprayed is not damaged by corrosion and does not cause thermal spray delamination. Further, this composite film has abrasion resistance and heat insulation as well as the conventional thermal spray coating.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an embodiment of the method of the present invention, and FIG. 2 is a sectional view of a thermal sprayed composite film formed by the above method. .

In FIG. 1, an object 1 to be sprayed is accommodated in an atmosphere control chamber 2, and an exhaust port 3 is provided on a side of the chamber 2 and connected to an exhaust device (not shown). At the center opening at the upper end of the atmosphere control chamber 2,
For example, an insulating cylinder 4 made of a quartz gas tube and having a closed upper end and an appropriate diameter.
A coil 5 made of, for example, a water-cooled copper tube is wound coaxially around the outer periphery of the vehicle, and connected to a high-frequency oscillator 6 having a maximum output of 80 kW and a frequency of 4 MHz, for example.

A working gas introduction hole 8 for introducing a working gas to be a high frequency induction plasma 7 is provided at a peripheral edge of a closed end of the insulating cylinder 4, and a high frequency induction plasma 7 melts at a central portion of the closed end. Sprayed powder material supply nozzle 1 to which a sprayed powder material to be formed into sprayed powder particles 9 is supplied.
0 is provided. Further, the sprayed powder material supply nozzle 10 is provided with a material supply device A containing a sprayed powder material having a particle size distribution evaporating by the amount of heat of the high frequency induction plasma 7, for example, a particle size of 10 to 40 μm.
Particle size distribution, eg 80-100μ
A material supply device B containing a sprayed powder material having a particle size of m is connected.

In such an apparatus configuration, first, the inside of the atmosphere control chamber 2 is evacuated from the exhaust port 3 by an exhaust device (not shown), and exhausted to a degree of vacuum of several Torr. This is to prevent the gas in the atmosphere from being mixed as impurities into the formed thermal spray composite film. Subsequently, a high-frequency current is supplied from the high-frequency oscillator 6 to the application coil 5 from the high-frequency oscillator 6 while introducing a working gas mixed with Ar: 40 l / min and H ₂ : 5 l / min into the insulating cylinder 4 from the working gas introduction hole 8. . Then, an alternating magnetic field is generated in the insulating cylinder 4, and the working gas flowing therein is excited to become the high frequency induction plasma 7.

Thereafter, the exhaust amount of the exhaust device is adjusted to maintain the pressure in the atmosphere control chamber 2 at atmospheric pressure or slightly reduced (about 500 Torr to atmospheric pressure), and at the same time, the output of the high frequency oscillator 6 is reduced. Adjust the setting output to 60 kW.

Therefore, the particle size of the material supply devices A and B is 10 to 10.
40 μm Al ₂ O ₃ spray powder material and particle size 80-100μ
m ₂ of Al ₂ O ₃ sprayed powder material at the same time
At a supply rate of 0 g / min, the sprayed powder material supply nozzle 10 supplies the high frequency induction plasma 7 together with a carrier gas of 5 l / min Ar.

The sprayed powder particles having a particle size of 10 to 40 μm are rapidly heated by the high-frequency induction plasma 7 due to the small particle size, and are evaporated by the heat of the high-frequency induction plasma 7 at the set output. On the other hand, particle size 80-100 μm
Since the thermal sprayed powder particles have a large particle size, the amount of heat of the high frequency induction plasma at the set output does not evaporate but only melts even if heated. Therefore, in the high-frequency induction plasma 7, there are the molten sprayed powder particles 9 and the evaporated matter at the molecular level.

Then, the melted sprayed powder particles 9 ride on the flow of the high frequency induction plasma 7 and reach the object 1 to be sprayed.
As shown in (1), the thermal spray coating particles 13 are deposited on the surface 1a of the object to be sprayed. At the same time, the evaporant is cooled down as it approaches the object 1 to be sprayed and forms ultra-fine particles 14, while depositing on the inter-particle boundaries of the thermal spray coating particles 13 attached to the surface 1 a of the object to be sprayed. As a result, as shown in FIG. 2, a thermal spray composite film 15 including the thermal spray coating particles 13 and the ultrafine particles 14 is formed.

Thus, in the spray composite film 15 formed on the surface 1a of the object to be sprayed, the ultrafine particles 14 are deposited on the boundary between the particles of the spray coating film 13 to exhibit a dense film structure as a whole. Since the thermal spray composite film 15 blocks the thermal sprayed object 1, the thermal sprayed object surface 1a is not corroded, and the dense thermal spray composite film 15 is in close contact with the thermal sprayed object surface 1a, so that thermal spray separation occurs. Never. Further, the thermal spray composite film 15 also has the same abrasion resistance and heat insulation as the conventional one.

[0017]

In summary, according to the present invention, when the thermal spray powder material is supplied into the high frequency induction plasma and sprayed on the object to be sprayed, the thermal spray powder material has a particle size distribution that evaporates due to the calorific value of the high frequency induction plasma. Simultaneously supplying a powder material and a sprayed powder material having a particle size distribution to be melted by the calorific value of the high-frequency induction plasma into the high-frequency plasma to form a sprayed composite film composed of ultrafine particles and sprayed coating particles on the surface of the object to be sprayed; As a result, the object to be sprayed is shielded from corrosive substances by the dense film structure as a whole, and is not corroded.
Further, the present invention is extremely useful industrially because a method for forming a sprayed composite film having sufficient abrasion resistance and heat insulation is obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a method for forming a sprayed composite film according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a sprayed composite film in the same method.

FIG. 3 is a schematic view showing a conventional plasma spraying method.

FIG. 4 is a cross-sectional view of the thermal spray coating in the same method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 spray target 1 a spray target surface 2 atmosphere control chamber 3 exhaust port 4 insulating cylinder 5 applied coil 6 high-frequency oscillator 7 high-frequency induction plasma 8 working gas introduction hole 9 spray powder particles 10 spray powder material supply nozzle 11 material supply device A 12 Material supply device B 13 Thermal spray coating particles 14 Ultra fine particles 15 Thermal spray composite film

Claims (1)

(57) [Claims] 1. A spraying powder material having a particle size distribution that evaporates due to the calorific value of the high-frequency induction plasma and the high-frequency induction plasma when the spraying powder material is supplied into the high-frequency induction plasma and sprayed on the object to be sprayed. A sprayed powder material having a particle size distribution that is melted by the amount of heat simultaneously supplied into the high-frequency plasma to form a sprayed composite film comprising ultrafine particles and sprayed coating particles on the surface of the object to be sprayed. Forming method.