JPH0251898A - Plasma spray gun - Google Patents

Abstract

PURPOSE:To obtain film having good adhesive strength and strongly resisting thermal and mechanical shock by changing the position of a supply port of a material to be flame-coated or the angle of supply thereof to plasma flame according to physical differences between materials to be flame-coated. CONSTITUTION:The positions of supply ports of a material to be flame-coated 5 and 6 are differentiated referring to the center-line direction of a plasma spray gun 1, or the angle of a supply passage of the material to be flame-coated is differentiated referring to the center-line direction of the plasma spray gun 1, or the positions of supply ports of a material to be flame-coated 5 and 6 are differentiated referring to the center-line direction of the plasma spray gun 1 and also the angle of a supply passage of the material to be flame-coated is differentiated referring to the center-line direction of the plasm spray gun. Thus, a plurality of materials to be flame-coated are supplied by changing the positions of supply ports of a material to be flame-coated or an angle of a supply passage thereof or a combination of the positions of supply ports and the angle of a supply passage thereof to carry out flame-coating at an arbitrary mixing rate with the result that it is possible to form film having good adhesive strength and strongly resisting thermal and mechanical shocks.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a coating layer with excellent adhesive strength on a base material by simultaneously supplying thermal spraying materials of different materials and forming a coating layer with an arbitrary mixing ratio. The present invention relates to a plasma spray gun for obtaining a sprayed coating.

[Prior art] In general, plasma spraying provides abrasion resistance and
It is described as a method for coating metals, ceramics, or cermets to provide heat resistance and corrosion resistance. The plasma spray gun is normally operated in the manner shown in FIG. 8 and described below. In Figure 8, the soil is the main body of the plasma spray gun, mainly the cathode (hereinafter referred to as tungsten electrode).
2, an anode (hereinafter referred to as a water-cooled copper electrode) 3, a plasma gas supply port 4, and a thermal spray material supply port 5. '6. The tungsten electrode 2 and the water-cooled copper electrode 3 are electrically separated by an insulator 7, and the tungsten electrode 2 is connected to the negative electrode of the DC type 6tXS, and the water-cooled copper electrode 3 is connected to the positive electrode.

9 is a plasma gas (usually argon, helium, hydrogen,
10 and 12 are thermal spray materials A of different materials.
and B (airtight hopper, 11,
13 is an inert gas (Ar, etc.) cylinder for feeding each thermal spraying material to each thermal spraying material supply port 5.6.

First, plasma gas is supplied from the gas cylinder 9 through the gas supply port 4, and a plasma arc is generated between the tungsten electrode 2 and the water-cooled copper electrode 3 by the DC type tX8. Due to the heat exchange between the arc and the plasma gas 7, a plasma flame I7 is formed and is ejected from above the plasma spray gun.

The base material 4 to be thermally sprayed has its surface to be thermally sprayed subjected to blasting or the like in advance, and is installed at a predetermined position. Thereafter, from the thermal spraying powder supply port 5, the thermal spraying powder A in the hopper 10 is transferred to the inert gas cylinder 11 to form the plasma flame 1.
At the same time, from the thermal spraying material supply port 6, the thermal spraying material B in the hopper 12 is similarly supplied to the plasma flame F using the inert gas from the inert gas bomb 12, and onto the base material 14 to be thermally sprayed. A method of thermal spraying is known.

[Problem to be solved by the invention]

However, the drawback of the plasma spraying method described above is that spraying materials with different physical properties, for example, ceramic-based (・A material) and metal-based (・B material) thermal spraying materials with significantly different melting points, are used at the respective material supply ports 5. When thermal spraying is performed by charging from 6, the spray material supply ports are placed at the same position with respect to the flow of the plasma flame and symmetrically with the tungsten electrode 2 as the center, so both of the spray powders charged are in the same temperature range at the same time. Pass through the plasma flame. For this reason, when a ceramic material with a high melting point is melted (for example, by increasing the plasma arc current and increasing the plasma energy density), the metal material with a low melting point evaporates and the desired mixed coating cannot be obtained. Furthermore, if the plasma energy density is reduced to melt the metal material, the ceramic material will not melt, and as a result, the adhesive strength between the base material and the coating will be low, and it will be susceptible to mechanical stress and thermal stress. If this happens, peeling may occur.

In addition, similar problems occur when other thermal spray materials have significantly different properties such as specific gravity, particle size, thermal conductivity, etc., and therefore differ in solubility.

[Means for Solving the Problems] The present invention provides a plasma spray gun capable of producing metal, ceramic or cermet coatings with high adhesive strength (and excellent resistance to thermal and mechanical impact). It is something.

That is, the features of the present invention include a cathode, a cylindrical anode provided on the outside of the cathode, a plasma gas supply port for ejecting plasma gas between the cathode and the anode, and a plasma flame in which a plurality of types of thermal spray materials are simultaneously ejected. In a plasma spray gun equipped with multiple spray material supply ports, the spray material supply ports may be placed at different positions in the direction of the center line of the plasma spray gun, or the angle of the spray material supply channel may be adjusted to Alternatively, the spray material supply ports may be provided at different positions in the direction of the center line of the plasma spray gun, and the angle of the spray material supply flow path may be set relative to the center line of the plasma spray gun. There is a plasma welding gun with a difference.

[Function] Here, the effect brought about by changing the position or supply angle of the spray material supply port relative to the plasma flame depending on the physical properties of the spray material will be explained with reference to FIG.

FIG. 7 shows an example of the temperature distribution on the central axis of the plasma flame near the thermal spray material supply port.

As shown in the figure, this temperature distribution characteristic generally shows that the temperature decreases along the flow direction of the plasma flame, and if there is a temperature gradient, it shows a remarkable tendency near the thermal spray powder supply port.

On the other hand, when spraying material is supplied from a position downstream of the plasma flame, it takes less time to reach the base material to be sprayed.
The large heat content of the sprayed material is reduced.

Therefore, for example, if the melting points of thermal spray materials are different, a high 1.
By arranging the spray material supply port upstream of the plasma flame, different materials with different melting points can be brought into a molten state and mixed to form a good coating. Further, providing a thermal spraying material supply angle also makes the above-described effects more effective.

Furthermore, the provision of a pair of supply ports symmetrically around the tungsten electrode 2 in Example 2 (see FIGS. 3 and 4) makes it possible to increase the amount of material in the plasma flame compared to a single supply port on one side. Distribution unevenness has been improved.

As a result, the effect of improving coating thickness unevenness has been experimentally confirmed.

(Example) Examples are shown in FIGS. 1 to 6 to specifically explain the features of the present invention.

As a first example, FIG. 1 shows a sectional view of a thermal spray gun showing one embodiment of the present invention, and FIG. 2 shows a cross-sectional view of the thermal spray gun shown in FIG.
An arrow view is shown.

In Figure 1, the upper part is the main body of the plasma spray gun, which mainly consists of a tungsten electrode 2, a water-cooled copper electrode 3, and a plasma gas supply port 4.
and thermal spray material supply ports 5 and 6. The feature of this embodiment is that the thermal spray material supply ports 5 and 6 are arranged to be shifted from the plasma flame in the direction of the center line of the plasma spray gun, and that, for example, two types of materials with significantly different melting points are used as the physical properties of the thermal spray materials. In this case, the material with a high melting point is supplied from the supply port 5 close to the plasma arc generation point, and vice versa, the material with a low melting point is supplied.
It is supplied from the supply port 6 in the downstream region of the plasma flame.

Next, as a second example, FIG. 3 shows a cross-sectional view of a thermal spray gun with an increased number of spray material supply ports compared to the thermal spray gun shown in FIG.
FIG. 4 shows a BB arrow view of the thermal spray gun shown in FIG.

In FIG. 3, the upper part is the plasma spray gun main body, which is mainly composed of a tungsten electrode 2, a water-cooled copper electrode 3, a plasma gas supply port 4, and a thermal spray material supply port 5, 6, 15, and 16. The feature of this embodiment is that two pairs of thermal spray material supply ports are provided symmetrically with respect to the tungsten electrode 2, and each pair of material supply ports is arranged offset from the plasma flame in the direction of the center line of the plasma spray gun. For example, when using two materials with significantly different melting points as thermal spray materials, the first
As in the example, the high melting point spray material is supplied from the supply port 5.6 in the -E region of the plasma flame, and the low melting point material is supplied from the supply port 15.16 in the downstream region of the plasma flame. Note that two or more pairs of material supply ports may be provided, and two or more types of thermal spraying materials may be used.

As a third example, FIG. 5 shows a cross-sectional view of the thermal spray gun in which the spraying material supply angle and the spraying material supply port position of the thermal spraying gun of the first example are changed, and FIG. -C arrow view is shown.

In FIG. 5, the same reference numerals as in FIG. 1 indicate items with the same functions as in FIG. 1.

The feature of this embodiment is that, whereas in the previous two embodiments, the spraying material injection angle was perpendicular to the plasma flame, the spraying material was The supply flow path is angled, and as in the previous example, the high melting point thermal spray material is supplied to the plasma flame from the upward supply port 5, and the low melting point material is supplied from the downward supply port 6.

Although not shown, the spray material supply ports may be placed at the same position and the angles of the spray material supply channels may be different, and if necessary, the above embodiments may be combined. There is also.

(Effects of the Invention) As explained above, in the present invention, multiple types of thermal spraying materials are applied by changing the position of the thermal spraying material supply port, the feeding angle, or the combination of the feeding position and angle to the plasma flame depending on the physical properties of the thermal spraying materials. By supplying and thermal spraying at an arbitrary mixing ratio, it became possible to form a coating with high adhesive strength and excellent resistance to thermal and mechanical impact.

In addition, as a ripple effect, by using the thermal spray gun of the present invention and changing the supply amount of each of multiple types of thermal spray materials over time, it becomes possible to continuously form a laminated thermal spray coating with a desired mixing ratio, Thick thermal sprayed coatings with high adhesive strength are possible.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a thermal spray gun, not showing one embodiment (first example) of the present invention, Fig. 2 is a view taken along arrow A-^ of the thermal spray gun of Fig. 1, and Fig. 3 is an embodiment of the present invention. 4 is a cross-sectional view of the thermal spray gun showing an embodiment (second example), FIG. 4 is a view taken along arrow B-8 of the thermal spray gun in FIG. 3, and FIG. 5 is a thermal spray gun showing an embodiment (third example) of the present invention. Figure 6 is a cross-sectional view of the thermal spray gun in Figure 5 taken along the line C-C, Figure 7 is the temperature distribution on the central axis of the plasma flame near the spray material supply port corresponding to the position of the spray gun, and Figure 8 is a cross-sectional view of the spray gun. FIG. 1 is a diagram illustrating a conventional plasma spraying method. Top...Thermal spray gun, 2...Tungsten electrode, 3...Water-cooled copper electrode, 4...Plasma gas supply port, 5, 6.15.16...Thermal spray material supply port, 7...
- Insulator, 8... DC power supply, 9... Plasma gas cylinder, 10, 12... Thermal spray material hopper 11, 13... Inert gas cylinder, 14... Base material to be sprayed, 17... plasma flame.

Claims (1)

[Claims] 1) Multiple types of thermal spraying materials are simultaneously directed toward a cathode, a cylindrical anode provided outside the cathode, a plasma gas supply port for ejecting plasma gas between the cathode and the anode, and a plasma flame. In a plasma spray gun that is equipped with multiple spray material supply ports, the spray material supply ports should be placed at different positions in the direction of the center line of the plasma spray gun, or the angle of the spray material supply channel should be adjusted to suit the plasma spray gun. Alternatively, the spray material supply ports may be provided at different positions in the direction of the center line of the plasma spray gun, and the angle of the spray material supply flow path may be set at a different angle from the center line of the plasma spray gun. A plasma spray gun characterized by being installed with a difference between the two.