JP2015091602A - Plasma spraying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma spraying device capable of forming a spray deposit with few oxides by reducing the surface oxidation of particulates being droplets.SOLUTION: A plasma spraying device includes: a primary gas nozzle 10 for forming a primary gas passage 11 along the circumference of a cathode 40 to cover the tip of the cathode 40; a secondary gas nozzle 20 arranged outside the primary gas nozzle 10 to form a secondary gas passage 21; and a tertiary gas nozzle 30 forming a tertiary gas passage 31 spraying a high-temperature tertiary gas receiving the heat of a plasma flame F to the circumference of the plasma flame F between the primary and secondary gas nozzles 10 and 20. Since the diffusion of the plasma flame is prevented by using an inert gas as the tertiary gas or a compressed air as the primary gas and besides, the surface oxidation of the particulates being droplets is reduced, it becomes possible to form a spray deposit with few oxides.

Description

  The present invention relates to a plasma spraying apparatus in which a plasma arc is transferred to an electrically conductive wire to generate a plasma flame, and the wire is sprayed while forming a droplet.

  FIG. 7 is a sectional view schematically showing a conventional plasma spraying apparatus. As shown in FIG. 7, a conventional plasma spraying apparatus 90 includes a primary gas nozzle 91 that forms a primary gas passage 91a, a secondary gas nozzle 92 that is disposed outside the primary gas nozzle 91 and forms a secondary gas passage 92a, Electrical conduction for thermal spraying in the vicinity of the cathode 93 disposed substantially on the central axis of the nozzle port 91 b of the primary gas nozzle 91 and the nozzle port 92 a of the secondary gas nozzle 92, the power supply device 94, and the nozzle port 92 a of the secondary gas nozzle 92. The wire guide hole 95 which supplies the property wire W is provided.

  The wire W is supplied obliquely forward from the wire guide hole 95 toward the central axis of the nozzle port 92a. The primary gas ejected from the primary gas passage 91a is connected to the wire W indirectly connected to the anode side of the power supply device 94 via the secondary gas nozzle 92 and the cathode 93 connected to the cathode side of the power supply device 94. Is formed into a plasma flame F by the arc generated between them, and the wire W is ejected as a droplet D. The droplet D is further refined by the secondary gas injected from the secondary gas passage 92a to the front of the secondary gas nozzle 92, further accelerated, and injected onto the workpiece T to form the sprayed coating S. .

  In such a conventional plasma spraying apparatus 90, an inert gas such as nitrogen gas or argon gas is used as a primary gas, and a compressed gas, a gas such as nitrogen gas or carbon dioxide gas is used as a secondary gas. (For example, refer to Patent Document 1). However, in actual operation, nitrogen gas, carbon dioxide gas, and the like as the secondary gas are expensive to operate, and thus compressed air that is low in cost is used. In the plasma spraying apparatus 90, the primary gas converted into plasma by the compressed air, which is the secondary gas, is encapsulated, so that the injection of the plasmaized primary gas can be made thin and the speed of the primary gas can be increased. It is possible.

JP-A-9-308970

  However, in the conventional plasma spraying apparatus 90, the molten droplets D of the wire W are made finer by the injection of the secondary gas, and a sufficient speed is given to each droplet D. The inner metal material is disturbed from the outer peripheral portion of the plasma flame F by abrupt narrowing of compressed air, which is a secondary gas, at the time of melting. Therefore, the surface of the particles that have become the droplet D is oxidized, and the thermal spray coating S contains an oxide of a metal material.

  Accordingly, an object of the present invention is to provide a plasma spraying apparatus capable of forming a sprayed coating with less oxide by reducing oxidation of the particle surface that has become droplets.

  The plasma spraying device of the present invention includes a cathode, a primary gas nozzle that forms a primary gas passage on the outer periphery of the cathode and covers the tip of the cathode, and a secondary gas passage that is disposed outside the primary gas nozzle to form a secondary gas passage. A secondary gas nozzle and a wire passage for supplying a wire for thermal spraying to the vicinity of the nozzle opening of the secondary gas nozzle, and the primary gas nozzle is ejected by an arc generated between the tip of the wire supplied from the wire passage and the cathode. Plasma is formed by converting the primary gas into plasma, forming a plasma flame that is ejected from the primary gas nozzle, and using the tip of the wire as a droplet, and this droplet is ejected onto the workpiece by the secondary gas that is ejected from the plasma flame and the secondary gas nozzle. In the thermal spraying apparatus, the outer periphery of the plasma flame receives heat from the plasma flame between the primary gas nozzle and the secondary gas nozzle. A tertiary gas nozzle for forming a tertiary gas passage for injecting a tertiary gas for high temperature gas injection is provided, and the tertiary gas is an inert gas or the primary gas is compressed air It is.

  According to the plasma spraying apparatus of the present invention, the inside of the tertiary gas flow injected from the tertiary gas passage disposed between the primary gas passage and the secondary gas passage receives the heat of the plasma flame and is a high-temperature gas. Form a jet. This high-temperature gas injection suppresses the disturbance generated from the outer periphery of the plasma flame by the rapid narrowing of the secondary gas injected to the outside and prevents the diffusion of the plasma flame. The surface oxidation is reduced.

  Here, compressed air or carbon dioxide gas can be used as the tertiary gas, but it is desirable to use an inert gas such as argon gas or nitrogen gas as the tertiary gas. When an inert gas is used as the tertiary gas, the disturbance generated from the outer periphery of the plasma flame due to the rapid constriction of the secondary gas is prevented, and the plasma flame is heated at the outer periphery of the plasma flame. Inert gas injection is formed. As a result, the droplet particles are refined and accelerated in the high-temperature inert gas injection, and are thus protected from oxidation by the secondary gas.

  In the plasma spraying apparatus of the present invention, it is possible to form a sprayed coating with less oxidation even when compressed air is used as the primary gas. When compressed air is used as the primary gas, the primary gas contains about 20% oxygen, but when the gas is turned into plasma, it is said that the action of oxidizing the molten metal is small. Even if compressed air is used as the primary gas, the thermal spray coating should be less oxidized. However, in the conventional plasma spraying equipment, when the plasma flame is disturbed by the rapid narrowing of the secondary gas, the oxidation of the droplets proceeds excessively. Decreases. On the other hand, in the plasma spraying apparatus of the present invention, the high temperature gas injection that receives the heat of the plasma flame is formed on the outer periphery of the plasma flame by the tertiary gas, so that the disturbance of the plasma flame due to the rapid narrowing of the secondary gas can be prevented. Therefore, even when compressed air is used as the primary gas, a sprayed coating with less oxidation can be formed.

(1) A tertiary gas nozzle is provided between the primary gas nozzle and the secondary gas nozzle to form a tertiary gas passage for injecting a tertiary gas for receiving a heat of the plasma flame and injecting a high temperature gas into the outer periphery of the plasma flame. Since the tertiary gas is an inert gas or the primary gas is compressed air, the diffusion of the plasma flame is prevented, and the oxidation of the surface of the particles that have become droplets is reduced. It becomes possible to form a few sprayed coatings.

(2) When an inert gas is used as the tertiary gas, a high-temperature inert gas jet that receives the heat of the plasma flame is formed on the outer periphery of the plasma flame, and the droplet particles are in the high-temperature inert gas jet. Therefore, it is possible to form a thermal spray coating that is further protected from oxidation by the secondary gas and contains less oxide.

(3) Even when compressed air is used as the primary gas, a high-temperature gas jet is formed on the outer periphery of the plasma flame by the tertiary gas, and the secondary gas is rapidly narrowed down. Since the plasma flame can be prevented from being disturbed, it is possible to form a sprayed coating with less oxidation.

It is a schematic block diagram of the plasma spraying apparatus in embodiment of this invention. It is a longitudinal cross-sectional view which shows the detail of the principal part of the plasma spraying torch of FIG. FIG. 3 is a view as seen from an arrow A in FIG. 2. It is operation | movement explanatory drawing of the plasma spraying torch of FIG. It is explanatory drawing which shows the cross-sectional shape of a wire channel | path, and the direction of the force which a wire receives. It is explanatory drawing which shows the natural potential measuring method. It is sectional drawing which showed the conventional plasma spraying apparatus typically.

  FIG. 1 is a schematic configuration diagram of a plasma spraying apparatus according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing details of a main part of the plasma torch of FIG. 1, FIG. 3 is a view taken along arrow A in FIG. FIG. 2 is an operation explanatory diagram of the plasma torch of FIG. 1.

  In FIG. 1, a plasma spraying apparatus 1 according to an embodiment of the present invention includes a plasma spraying torch 2 that sprays a wire W formed as droplets by a plasma flame onto an object to be processed, and a primary gas and a secondary to the plasma spraying torch 2. A gas supply source 3 for supplying gas, a power supply 4 for supplying operating power to the plasma spraying torch 2, a wire reel 5 around which the wire W is wound, and a winding wrinkle of the wire W drawn from the wire reel 5 are corrected. A wire straightening machine 6 and a wire supply mechanism 7 for supplying the wire W to the plasma spraying torch 2 by a wire feed tube 8 are provided.

  As shown in FIG. 2, the plasma spray torch 2 includes a primary gas nozzle 10 that forms a primary gas passage 11, a secondary gas nozzle 20 that is disposed outside the primary gas nozzle 10 and forms a secondary gas passage 21, and a primary gas nozzle. 10 and the secondary gas nozzle 20 are arranged on substantially the central axes of the tertiary gas nozzle 30 that forms the tertiary gas passage 31 and the nozzle port 12 of the primary gas nozzle 10 and the nozzle port 22 of the secondary gas nozzle 20. A cathode 40 and a wire passage 50 for supplying the wire W for thermal spraying to the vicinity of the nozzle port 22 of the secondary gas nozzle 20 are provided.

  The primary gas nozzle 10 is formed so as to cover the tip of the cathode 40, and the primary gas passage 11 is formed on the outer periphery of the cathode 40. The primary gas supplied to the primary gas passage 11 is a gas for generating a plasma flame and making the tip of the wire a droplet, and is an inert gas such as nitrogen gas or argon gas. Alternatively, compressed air can be used as the primary gas. The primary gas supplied by the primary gas passage 11 is supplied while turning around the outer periphery of the cathode 40, and is injected from the nozzle port 12 of the primary gas nozzle 10 to the front of the secondary gas nozzle 20.

  The tertiary gas nozzle 30 is formed so as to wrap the outside of the primary gas nozzle 10, and a tertiary gas passage 31 is formed on the outer periphery of the primary gas nozzle 10. The tertiary gas is a gas for forming a high-temperature gas jet by receiving the heat of the plasma flame at the outer peripheral portion of the plasma flame generated by the primary gas, and is a gas such as compressed air or carbon dioxide gas. The secondary gas nozzle 20 is formed so as to wrap around the outer side of the tertiary gas nozzle 30, and a secondary gas passage 21 is formed on the outer periphery of the tertiary gas nozzle 30. The secondary gas is sprayed so as to be rapidly narrowed from the outside with respect to the plasma flame formed by the primary gas to make the droplets finer, and give a sufficient velocity to the droplets to be covered. It is a gas for injecting on a processed material, and is a gas such as compressed air or carbon dioxide.

  The primary gas preferably has a flow rate in the range of 50 to 120 [L / min] in order to appropriately change the temperature, speed, and generated voltage of the plasma flame by changing the gas flow rate. In addition, when the flow rate of the primary gas is less than 50 [L / min], the speed of the plasma flame becomes slow, and the quality of the sprayed coating is deteriorated. On the other hand, when the flow rate of the primary gas exceeds 120 [L / min], the plasma flame speed is high and the temperature is lowered, so that the quality of the sprayed coating is lowered.

  As described above, the secondary gas is injected so as to be rapidly narrowed from the outside with respect to the injection of the plasma flame formed by the primary gas, making the droplets finer and at a sufficient speed for the droplets. Therefore, the flow rate is preferably 250 to 500 [L / min]. If the flow rate of the secondary gas is less than 250 [L / min], it is insufficient to make the droplet fine, and the effect of giving a sufficient speed to the droplet is reduced. Quality deteriorates. On the other hand, when the flow rate of the secondary gas exceeds 500 [L / min], the droplets become excessively fine and the droplets are excessively cooled, so that the quality of the sprayed coating is deteriorated.

  Since the tertiary gas receives the heat of the plasma flame at the outer periphery of the plasma flame generated by the primary gas as described above and forms a high temperature gas jet, the volume ratio is set to a range of 20 to 50% of the flow rate of the primary gas. And in order to suppress the disturbance and gas diffusion of the plasma flame due to the secondary gas injection, it is desirable that the volume ratio is in the range of 5 to 10% of the flow rate of the secondary gas. In addition, in order to more effectively exert the effect of suppressing the disturbance of the plasma flame and gas diffusion due to the secondary gas injection, the flow rate of the tertiary gas is changed in conjunction with the increase and decrease of the flow rate of the secondary gas, When the flow rate is small, it is desirable to reduce the flow rate of the tertiary gas, and when the flow rate of the secondary gas is high, it is desirable to increase the flow rate of the tertiary gas.

  If the flow rate of the tertiary gas is less than 20% of the flow rate of the primary gas or less than 5% of the flow rate of the secondary gas, the effect of suppressing the disturbance of the plasma flame and gas diffusion by the injection of the tertiary gas is reduced. The effect of improving the quality of the film is difficult to obtain. On the other hand, when the flow rate of the tertiary gas is more than 50% of the flow rate of the primary gas or more than 10% of the flow rate of the secondary gas, the injection of the tertiary gas is strong, and the inside receives the heat of the plasma flame. Therefore, it becomes insufficient to form a high-temperature gas jet, and the effect of suppressing the disturbance of the plasma flame and the gas diffusion cannot be sufficiently exhibited, so that it is difficult to obtain the effect of improving the quality of the sprayed coating.

  The wire passage 50 includes a primary wire passage 51a having a wire outlet 51b formed in the vicinity of the nozzle port 22 of the secondary gas nozzle 20, and a wire W for supplying the wire W at a predetermined inclination angle θ to the primary wire passage 51a. And a next wire passage 52a. The wire passage 50 gives the wire W a bend in a range not exceeding the elastic limit by the primary wire passage 51a and the secondary wire passage 52a.

  As shown in FIG. 3, the primary wire passage 51 a has a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame, and linearly penetrates the primary wire guide member 51 disposed outside the secondary gas nozzle 20. Is formed. Similarly, the secondary wire passage 52a also has a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame, and linearly penetrates the secondary wire guide member 52 disposed at a position away from the primary wire passage 51a. Is formed.

  The width a in the long side direction of the primary wire passage 51a is set larger than the diameter d of the wire W in a range of 10% to 95%. The width b in the short side direction of the primary wire passage 51a is set to be larger than the diameter d of the wire W in a range of 3% or more and less than 10%. In this embodiment, the diameter d of the wire W is 1.6 mm, the width a in the long side direction is about 0.2 to 1.5 mm larger than the diameter d of the wire W, and the width b in the short side direction is the wire It is set larger by 0.05 to 0.15 mm than the diameter d of W. The same applies to the secondary wire passage 52a.

  In addition, the substantially rectangular cross-sectional shape which the primary wire channel | path 51a and the secondary wire channel | path 52a have is C-shaped chamfering, R-chamfering, etc. in the range which the outer surface of the wire W does not contact | connect the corner | angular part of rectangular cross-sectional shape other than rectangular cross-sectional shape. Including shapes that have been processed. Therefore, in this embodiment, the wire W receives only a force in the vertical direction with respect to either the long side plane or the short side plane in the primary wire path 51a and the secondary wire path 52a. Become.

  Further, the inclination angle θ with respect to the primary wire passage 51a of the secondary wire passage 52a is an angle formed by the center line of the primary wire passage 51a and the center line of the secondary wire passage 52a. In the present embodiment, the inclination angle θ is set to about 1 to 5 °. The secondary wire guide member 52 is provided at a position where the primary wire passage 51a and the secondary wire passage 52a are arranged with a gap c therebetween. In the present embodiment, the gap c is set to about 3 to 10 mm.

  Thus, in the plasma spraying torch 2 in the present embodiment, the primary wire passage 51a and the secondary wire passage 52a are arranged with the gap c therebetween, so that the linear primary wire passage 51a and the secondary wire passage 52a are respectively arranged. Thus, a pseudo-curved wire passage 50 is formed, and the wire W is bent in a range not exceeding the elastic range. Note that the primary wire passage 51a and the secondary wire passage 52a may be curved.

  The anode side of the power source 4 is connected to the primary wire guide member 51 and is indirectly connected to the wire W passing through the primary wire passage 51 a of the primary wire guide member 51. On the other hand, the cathode side of the power supply 4 is connected to the cathode 40. Note that the anode side of the power supply 4 may be directly connected to the wire W.

  In the plasma spraying apparatus 1 having the above configuration, when the wire W wound around the wire reel 5 is fed to the plasma spraying torch 2 by the wire supply mechanism 7, the strong curl of the wire W is corrected by the wire straightening machine 6, It is stretched into a gentle curve. Then, the wire W is supplied to the wire passage 50 via the wire feed tube 8. In the wire path 50, the wire W receives only a force in the vertical direction with respect to either the long side plane or the short side plane in the primary wire path 51a and the secondary wire path 52a. As shown in FIG. 4, the bending in the range not exceeding the elastic limit is given in the extending direction of the plasma frame F.

  Here, since the primary wire passage 51 a and the secondary wire passage 52 a have a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame F, the warp is released in the extending direction of the plasma frame F. In particular, in the present embodiment, the width b in the short side direction is set to be larger than the diameter d of the wire W in a range of 3% or more and less than 10%. It is not escaped in the right angle direction. Therefore, even if the position of the distal end portion of the wire W is slightly displaced with respect to the extending direction of the plasma frame F, the displacement of the plasma frame F in the direction perpendicular to the extending direction of the plasma frame F is prevented. It will be located on the axis.

  FIG. 5 shows the cross-sectional shape of the wire passage and the direction of the force applied to the wire. In FIG. 5, a substantially rectangular cross section A is a rectangular cross section shape, a substantially rectangular cross section B is a shape in which a corner portion of the rectangular cross section is C-chamfered in a range where the outer surface of the wire W does not contact, and a substantially rectangular cross section C is a rectangular shape. The corner portion of the cross-sectional shape is a shape that has been subjected to R chamfering as long as the outer surface of the wire W does not contact. In these substantially rectangular cross-sectional shapes, regardless of whether the wire W is in contact with the plane in the long side direction or the plane in the short side direction, only the force in the direction perpendicular to each plane is received.

  Since the wire W cannot be completely straightened even by the wire straightening mechanism 7, the warp remains. The wire feed tube 8 is bent into various states and does not have a constant shape due to the handling of the plasma spraying torch 2 during operation. For this reason, when the wire W with the distortion remains in the wire feed tube 8 whose shape is not constant as described above, bending or twisting force acts on the wire W in accordance with the shape of the wire feed tube 8. By this bending or twisting force, the wire W is bent freely like the spring within the elastic limit, and is fed while meandering in the wire feed tube 8 at a position where the direction of the force is stable.

  At this time, in the above-described substantially rectangular cross-sectional shape, when the wire W is in contact with the plane in the short side direction, the direction perpendicular to the plane in the short side direction, that is, the extending direction of the plasma frame F (hereinafter, “X The distortion warp is released in the extending direction of the plasma flame F. When a force in a direction perpendicular to the extending direction of the plasma frame F (hereinafter referred to as “Y direction”) is applied while only in contact with the plane in the short side direction, the wire W Moves freely by the gap of the width b in the short side direction and touches the plane in the long side direction. In this case, too, the force in the vertical direction (Y direction) acts on the plane in the long side direction. The position of is stable. In particular, when a twisting force is applied, the forces in the X direction and the Y direction are distributed to the forces in the short side direction and the long side direction, and the force acts in the direction perpendicular to each surface, causing the wire W to twist. In order to act to suppress, the position of the wire W is stabilized.

  On the other hand, in the case of a round cross section or a long round cross section, when the wire W is in contact with the curved surface of the round cross section or the long round cross section, it receives only a force perpendicular to the curved surface. Can move freely along. In particular, when the twisting force is received, the wire W freely rotates along the curved surface, and thus the twist of the wire W is not suppressed. For this reason, the direction of the force received by the wire W is not determined, and the position of the wire W is indefinite.

  As described above, in the plasma spraying apparatus 1 according to the present embodiment, the tip portion of the wire W can stably supply the wire W to the central portion of the plasma frame F. And the primary gas ejected from the primary gas passage 11 is connected to the anode side of the power supply 4 indirectly via the primary wire guide member 51, and the cathode 40 connected to the cathode side of the power supply 4. The plasma generated by the arc generated during the period becomes a plasma flame F, and the wire W is ejected as a droplet D. The droplet D is further refined by the secondary gas injected from the secondary gas passage 21 to the front of the secondary gas nozzle 20, further accelerated, and injected onto the workpiece T to form the sprayed coating S. .

  At this time, in the plasma spraying apparatus 1 in the present embodiment, the inside of the tertiary gas flow injected from the tertiary gas passage 31 disposed between the primary gas passage 11 and the secondary gas passage 21 is in the plasma flame F. Upon receiving heat, a high-temperature gas jet G is formed. By suppressing the disturbance generated from the outer peripheral portion of the plasma flame F due to the rapid narrowing of the secondary gas injected to the outside by the high-temperature gas jet G, gas diffusion in the plasma flame F can be prevented, Oxidation of the surface of the particles that have become the droplet D is reduced. Thereby, it is possible to form the sprayed coating S with less oxidation on the workpiece T.

  Further, in this way, in the plasma spraying apparatus 1 according to the present embodiment, the high temperature gas injection that receives the heat of the plasma flame F is formed on the outer periphery of the plasma flame F by the tertiary gas, and the secondary gas is rapidly narrowed down. Since the disturbance of the plasma flame | frame F can be prevented, even if it is a case where compressed air is used as a primary gas, it is possible to form the sprayed coating S with little oxidation.

  In addition, when nitrogen gas, argon gas, or the like, which is an inert gas, is used as the tertiary gas, the disturbance generated from the outer peripheral portion of the plasma flame F due to the rapid constriction of the secondary gas as described above is prevented. A high-temperature inert gas jet that receives the heat of the plasma flame F is formed on the outer periphery of the plasma flame F. Thereby, the particles of the droplet D are protected from being oxidized by the secondary gas because they are refined and accelerated in a state in which the change in the components of the particles is prevented by high-temperature inert gas injection. Thereby, it becomes possible to form the thermal spray coating S with less oxidation.

  In the present embodiment, both the primary wire passage 51a and the secondary wire passage 52a have a substantially rectangular cross-sectional shape that is long in the extension direction of the plasma frame, but only one of them is in the extension direction of the plasma frame. It is also possible to have a long substantially rectangular cross-sectional shape. In this case, the warp of the wire W is released in the extending direction of the plasma frame F by the primary wire passage or the secondary wire passage having a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame, and the tip portion of the wire W is moved to the plasma frame. It can be supplied to the center of F.

  A comparative test was performed when compressed air and nitrogen gas, which is an inert gas, were used as the tertiary gas, and when no tertiary gas was used. In this example, an aluminum alloy was used as the thermal spray material, and the natural potential of the thermal spray coating was measured as an index of the degree of oxidation of the thermal spray coating to confirm the effect of the tertiary gas. Furthermore, as a method of reducing running costs, all gases of primary gas, secondary gas, and tertiary gas are created using inexpensive compressed air, and the natural potential of the sprayed coating is measured to determine the tertiary gas. The effect of was confirmed. FIG. 6 is an explanatory diagram showing a natural potential measurement method.

  As shown in FIG. 6, the natural potential is measured by creating a 5 w% NaCl environment on the sprayed coating surface of the test piece (test TP) using a salt bridge of saturated KCl, and using a saturated silver chloride electrode as a reference electrode. The natural potential was measured with a tester. In order to stabilize the measured value of the potential, the potential after 600 seconds from the start of measurement was taken as the measured value. A summary of the test results is shown in Table 1, and the results of measuring the natural potential of the film under the conditions shown in Table 1 are shown in Table 2.

  As shown in Table 1, when the tertiary gas was not used and when the compressed gas was used as the tertiary gas, the potential using the compressed air as the tertiary gas was lower by about 60 mV. In addition, when nitrogen gas, which is an inert gas, was used as the tertiary gas, the value was reduced by about 150 mV. Furthermore, when inexpensive compressed air was used for all the gases, the value was about 50 mV lower. From this, it was confirmed that by using the tertiary gas, there was little oxidation inside the sprayed coating.

  The plasma spraying apparatus of the present invention is useful as an apparatus for forming a rust-proof spray coating on the surface of a steel structure.

DESCRIPTION OF SYMBOLS 1 Plasma spraying apparatus 2 Plasma spraying torch 3 Gas supply source 4 Power supply 5 Wire reel 6 Wire straightening machine 7 Wire supply mechanism 10 Primary gas nozzle 11 Primary gas passage 12 Nozzle port 20 Secondary gas nozzle 21 Secondary gas passage 22 Nozzle port 30 Tertiary gas nozzle 31 Tertiary gas passage 40 Cathode 50 Wire passage 51 Primary wire guide member 51a Primary wire passage 52 Secondary wire guide member 52a Secondary wire passage

Claims (2)

A cathode, a primary gas nozzle that forms a primary gas passage on the outer periphery of the cathode and covers the tip of the cathode, a secondary gas nozzle that is disposed outside the primary gas nozzle to form a secondary gas passage, and the secondary gas nozzle A wire passage for supplying a wire for thermal spraying to the vicinity of the nozzle opening of the gas nozzle, and a primary gas injected from the primary gas nozzle by an arc generated between the tip of the wire supplied from the wire passage and the cathode. Plasma is formed, a plasma flame is ejected from the primary gas nozzle, the tip of the wire is used as a droplet, and the droplet is ejected onto the object to be processed by the secondary gas ejected from the plasma flame and the secondary gas nozzle. In plasma spraying equipment,
A tertiary gas nozzle is formed between the primary gas nozzle and the secondary gas nozzle to form a tertiary gas passage for injecting a tertiary gas for receiving a heat of the plasma flame and injecting a high temperature gas into an outer peripheral portion of the plasma flame. Prepared,
The plasma spraying apparatus, wherein the tertiary gas is an inert gas. A cathode, a primary gas nozzle that forms a primary gas passage on the outer periphery of the cathode and covers the tip of the cathode, a secondary gas nozzle that is disposed outside the primary gas nozzle to form a secondary gas passage, and the secondary gas nozzle A wire passage for supplying a wire for thermal spraying to the vicinity of the nozzle opening of the gas nozzle, and a primary gas injected from the primary gas nozzle by an arc generated between the tip of the wire supplied from the wire passage and the cathode. Plasma is formed, a plasma flame is ejected from the primary gas nozzle, the tip of the wire is used as a droplet, and the droplet is ejected onto the object to be processed by the secondary gas ejected from the plasma flame and the secondary gas nozzle. In plasma spraying equipment,
A tertiary gas nozzle is formed between the primary gas nozzle and the secondary gas nozzle to form a tertiary gas passage for injecting a tertiary gas for receiving a heat of the plasma flame and injecting a high temperature gas into an outer peripheral portion of the plasma flame. Prepared,
The plasma spraying apparatus, wherein the primary gas is compressed air.

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