KR102424988B1 - Method for controlling plasma spray device - Google Patents

Abstract

Provided are a plasma spraying apparatus capable of precisely manufacturing a coating layer by accelerating molten particles forming a coating layer, and a method for controlling the same. Plasma spraying device is a first positive electrode spaced apart from the i) negative electrode, ii) the negative electrode to form a first space, and a passage is formed therein, iii) the first positive electrode accelerates through the first positive electrode, and the gas is applied to form a jet. a second positive electrode and a second spaced apart space are formed along the a third positive electrode that forms a space and is positioned opposite the first positive electrode along the traveling direction with the second positive electrode interposed therebetween; v) a first positive electrode electrically connected to the first positive electrode and applying a first voltage to the first positive electrode 1 power source, vi) a second power source that is provided independently of the first power source, is electrically connected to the second positive electrode to apply a second voltage, and vii) is provided independently of the first power source and the second power source, and a third power source electrically connected to the third positive electrode to apply a third voltage.

Description

Control method of plasma spraying device {METHOD FOR CONTROLLING PLASMA SPRAY DEVICE}

The present invention relates to a plasma spraying apparatus and a method for controlling the same. More particularly, it relates to a plasma spraying apparatus capable of densely manufacturing a coating layer by reducing the size of molten fine particles forming the coating layer, and a method for controlling the same.

In order to protect high-temperature components or corrosion-resistant components, for example, superalloy-based materials applied to gas turbine engines or gas chamber inner walls from high-temperature gases, a thermal barrier coating made of a high-melting-point material is required. A thermal spraying method such as atmospheric plasma spray (APS) is used for thermal barrier coating. In atmospheric plasma spraying, mixed powder is used. When mixed powder is used, mixed powder of various composition ratios must be prepared in advance and the powder must be continuously replaced during the thermal spraying process. In addition, since powder is used as a raw material, powders having different sizes and densities may be supplied to form a coating that is not uniformly mixed.

On the other hand, in order to replace the atmospheric plasma spraying method, the suspension plasma spraying method (suspension plasma spray, SPS) is also used. Since the coating raw material is supplied as a liquid suspension, the mixing between different component materials is more uniform than the mixed powder, and fine volume control is possible due to the nature of the liquid. Accordingly, the composition of the coating is uniform in the horizontal direction, and continuity of composition change can be achieved even in the thickness direction, so that a coating layer having a gradient function can be manufactured.

Korean Patent No. 1,398,884

An object of the present invention is to provide a plasma spraying apparatus capable of forming a dense coating layer while having a high deposition rate. In addition, an object of the present invention is to provide a method of controlling a plasma spraying apparatus using the aforementioned plasma spraying apparatus.

Plasma spraying apparatus according to an embodiment of the present invention is accelerated through i) a negative electrode, ii) a first positive electrode spaced apart from the negative electrode to form a first spaced space, a first positive electrode having a passage therein, and iii) a first positive electrode A second positive electrode that forms a space between the first positive electrode and the second spaced apart space along the flow direction of the gas applied to be plasma jetted, is positioned opposite the negative electrode with the first positive electrode therebetween, and surrounds the passage therein, iv) a third positive electrode spaced apart from the second positive electrode to form a third separation space, and a third positive electrode positioned opposite to the first positive electrode along the traveling direction with the second positive electrode interposed therebetween; v) electrically connected to the first positive electrode; a first power source for applying a first voltage to the positive electrodes, vi) a second power source provided independently of the first power source, and electrically connected to the second positive electrode to apply a second voltage, and vii) the first power source and the first power source and a third power source provided separately from the second power source and electrically connected to the third positive electrode to apply a third voltage.

Plasma spraying apparatus according to an embodiment of the present invention, the first separation space, the second separation space, the third separation space, the first positive electrode, the second positive electrode, the third positive electrode and the gas is sprayed to the outside of the plasma spraying apparatus It may further include a suspension injection tube adapted to supply a suspension to the passage at one or more positions selected from the group consisting of the outer portion of the third positive electrode. The gas may be applied to atomize and melt the droplets contained in the suspension.

The inner diameter of the third positive electrode surrounding the passage may be greater than the inner diameter of the second positive electrode surrounding the passage, and the inner diameter of the second positive electrode may be greater than the inner diameter of the first positive electrode surrounding the passage. The first ratio of the inner diameter of the second positive electrode to the inner diameter of the first positive electrode greater than the second ratio of the inner diameter of the third positive electrode to the inner diameter of the second positive electrode may be 1.3 to 2 of the second ratio.

A method of controlling a plasma spraying apparatus according to an embodiment of the present invention comprises: i) a negative electrode, ii) a first positive electrode spaced apart from the negative electrode to form a first spaced space, a first positive electrode having a passage therein, iii) a first positive electrode A second positive electrode is formed on the opposite side of the negative electrode with the first positive electrode interposed therebetween and a second positive electrode surrounding the passage therein to form a first positive electrode and a second spaced apart space along the traveling direction of the gas applied to form a plasma jet while being accelerated through the second positive electrode , iv) a third positive electrode spaced apart from the second positive electrode to form a third separation space, and positioned opposite the first positive electrode along the traveling direction with the second positive electrode interposed therebetween, v) a first positive electrode electrically connected to the first positive electrode 1 power source, vi) a second power source provided independently of the first power source and electrically connected to the second positive electrode, vii) a second power source provided independently of the first power source and the second power source, and electrically connected to the third positive electrode 3 providing a plasma spraying device including a power source, the first power source applying a first voltage to the first positive electrode, the second power source applying a second voltage greater than the first voltage to the second positive electrode, and applying, by the third power source, a third voltage greater than the second voltage to the third positive electrode.

The control method of the plasma spraying apparatus according to an embodiment of the present invention is a first separation space, a second separation space, a third separation space, the first positive electrode, the second positive electrode, the third positive electrode and the gas to the outside of the plasma spraying apparatus The method may further include supplying one or more suspensions to the passage at one or more positions selected from the group consisting of the outer side of the third positive electrode to be sprayed, and atomizing the droplets included in the suspension by gas. In the step of supplying the suspension, the one or more suspensions may include a first suspension and a second suspension. The first suspension is supplied to the passage through the first positive electrode, the second suspension is supplied to the passage through the third separation space, and the first material included in the first suspension and the second material included in the second suspension are The compound is formed by plasma spraying, and the difference between the melting point of the first material and the melting point of the second material may be 500° C. or more.

In the step of supplying the suspension, the one or more suspensions may include a first suspension and a second suspension. The first suspension is supplied to the passage through the first positive electrode, the second suspension is supplied to the passage through the outer part, and the first material included in the first suspension and the second material included in the second suspension are formed of a compound and can be plasma sprayed.

In the step of applying the third voltage to the third positive electrode, the third voltage is 1.5 to 2 times the second voltage, and in the step of applying the second voltage to the second positive electrode, the second voltage is 3 times the first voltage to 4 times.

A coating material may be prepared by accelerating the molten particles forming the coating layer using a plasma spraying device. As a result, it is possible to obtain a product that can be used for a long time even in a corrosion-resistant atmosphere by manufacturing a coating material with excellent process efficiency and a dense structure.

1 is a schematic exploded view of a plasma spraying apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic perspective view of the plasma spraying apparatus of FIG. 1 .
3 is a voltage variation graph of a typical DC arc plasma.
4 and 5 are graphs of voltage variation of DC arc plasma during operation of the plasma spraying apparatus of FIG. 1 .
6 is a schematic operation conceptual diagram of the plasma spraying apparatus of FIG. 1 .
7 is a graph schematically illustrating a method for manufacturing α-alumina using the plasma spraying apparatus of FIG. 1 .
8 is an operation conceptual diagram of a plasma spraying apparatus according to a second embodiment of the present invention.
9 is an operation conceptual diagram of a plasma spraying apparatus according to a third embodiment of the present invention.

The terminology used herein is for the purpose of referring to specific embodiments only, and is not intended to limit the invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising," as used herein, specifies a particular characteristic, region, integer, step, operation, element and/or component, and other specific characteristic, region, integer, step, operation, element, component, and/or group. It does not exclude the existence or addition of

Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Commonly used terms defined in the dictionary are additionally interpreted as having a meaning consistent with the related art literature and the presently disclosed content, and unless defined, are not interpreted in an ideal or very formal meaning.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

1 schematically shows a disassembled structure of a plasma spraying apparatus 100 according to a first embodiment of the present invention. The structure of the plasma spraying apparatus 100 of FIG. 1 is only for illustrating the present invention, and the present invention is not limited thereto. Accordingly, the structure of the plasma spraying apparatus may be modified into other forms.

As shown in FIG. 1 , the plasma spraying apparatus 100 includes a negative electrode 10 , positive electrodes 12 , 14 , 15 , insulators 11 , 13 , 16 , 18 , 19 and a pair of support rods. (17). In addition, the plasma spraying apparatus 100 may further include necessary components. The positive electrodes 12 , 14 , and 15 include a first positive electrode 12 , a second positive electrode 14 , and a third positive electrode 15 . The first positive electrode 12 , the second positive electrode 14 , and the third positive electrode 15 form a tubular shape, and a gas and a plasma jet flow therein.

The negative electrode 10 and the first positive electrode 12 are spaced apart from each other. A gas for a plasma jet such as argon or helium is injected into the gas pipe 31 (shown in Fig. 2). These gases form an arc plasma jet. The first positive electrode 12 , the second positive electrode 14 , and the third positive electrode 15 sequentially form spaced apart spaces along the flow direction of the plasma jetted gas.

The negative electrode 10, the first positive electrode 12, the second positive electrode 14, and the third positive electrode 15 are spaced apart from each other to form a space or an insulator is inserted therebetween to prevent a short circuit caused by mutual contact. do. That is, the negative electrode 10, the first positive electrode 12, the second positive electrode 14, and the third positive electrode 15 are spaced apart from each other using the insulators 11, 13, 16, 18, and 19 to prevent a short circuit from occurring. can be prevented The insulators 11 , 13 , 16 , 18 , 19 include a first insulator 11 , a second insulator 13 , a third insulator 16 , a fourth insulator 18 and a fifth insulator 19 . do. For insulation, the insulators 11 , 13 , 16 , 18 , and 19 may be made of an electrically insulating material such as ceramic. The first positive electrode 12 may be accommodated and fixed inside the third insulator 16 . The front surface 161 of the third insulator 16 receives and fixes the first positive electrode 12 in contact with the second positive electrode 14 . Accordingly, the first positive electrode 12 and the second positive electrode 14 may be spaced apart from each other. In addition, as shown by a dotted line, the protrusion 163 of the third insulator 16 is inserted and fixed into the through hole 131 of the second insulator 13 . In addition, the negative electrode 10 is inserted and fixed in the through hole 131 from the rear thereof. As a result, the negative electrode 10 and the first positive electrode 12 can be spaced apart and fixed.

The pair of support rods 17 are inserted into the screw hole 111 of the first insulator 11 and the screw hole 181 of the fourth insulator 18 as shown by the dotted arrow, and the plasma spraying apparatus 100 ) is fixed. Although not shown in FIG. 1 for convenience, another pair of support rods are inserted into the screw holes 191 of the fifth insulator 19 to fix the plasma spraying apparatus 100 .

The first positive electrode 12 is initially ignited using an igniter such as an arc start for welding. When the first positive electrode 12 is stabilized, a voltage is applied to the second positive electrode 14 to reach an appropriate current value in the constant current mode. In the second positive electrode 14 , an arc load is formed in addition to the arc generated by the first positive electrode 12 , and is regulated in the constant current mode. The second positive electrode 14 allows the plasma of the first positive electrode 12 to act as a conducting wire so that a current is applied thereto.

FIG. 2 schematically shows a perspective view of the plasma spraying apparatus 100 of FIG. 1 . The structure of the plasma spraying apparatus 100 of FIG. 2 is only for illustrating the present invention, and the present invention is not limited thereto. Accordingly, the structure of the plasma spraying apparatus 100 may be modified into other forms.

As shown in FIG. 2 , a plasma jet gas is injected through the gas pipe 31 to drive the plasma spraying apparatus 100 . Since the negative electrode 10 (shown in FIG. 1, hereinafter the same) and the first positive electrode 12 (shown in FIG. 1, hereinafter the same) are inserted into the second insulator 13 and the third insulator 16, from the outside not visible The second positive electrode 14 is positioned opposite to the negative electrode 10 with the first positive electrode 12 interposed therebetween. And the third positive electrode 15 is positioned opposite to the first positive electrode 12 with the second positive electrode 14 interposed therebetween.

In contrast to the plasma spraying apparatus 100 according to the first embodiment of the present invention, there is a plasma spraying apparatus for generating multiple arc variations of a single electrode by disposing multiple negative or positive electrodes in the width direction thereof. However, this plasma spraying device is expensive because power is operated independently for each electrode. In addition, since the degree of damage to the negative electrode used as the common electrode is large, the negative electrode must also be separated for each power to make three guns as one. This is more than 5 times compared to single electrode spraying, for example, about 600 million won, so it is difficult to use.

On the other hand, there is a method of refining the powder input as a raw material and melting the powder with a fixed current in which constant current type power is provided even in a low voltage arc transition state. However, if the powder is too fine, the free movement of the fine powder makes it difficult to transport. Therefore, it is preferable to use plasma spraying using a suspension in which powder is mixed with liquid as in an embodiment of the present invention. Hereinafter, the basic operating principle of the plasma spraying apparatus 100 according to an embodiment of the present invention will be described in more detail with reference to FIGS. 3 and 4 .

3 is a voltage variation graph of a typical DC arc plasma.

As shown in FIG. 3 , in the single-electrode state, three voltage variations occur in DC arc plasma. When this is represented as a state in which the positive electrode and the arc are in contact, it is defined as a restrike, a takeover, and a steady state. This arc shape is observed in Ohm's Law (V=IR), where I is supplied from a constant current type power, and the arc load changes periodically depending on the flow of gas, the degree of plasmaization, and the health of the electrode, resulting in voltage variation. do.

The shape of the voltage transition that can be used for thermal spraying occurs in a mixed range of restrike and takeover. This voltage variation affects quality degradation such as delamination of the plasma spray coating. In order to avoid such voltage variations, a method of applying a high voltage of 200V or more used in a plasma cutting apparatus for cutting iron plates, etc. and a method of applying a low voltage of 80V or less are known. In addition, a method of pulverizing the material to be melted is also possible, but suspension is required due to difficulties in transport.

4 and 5 are graphs showing voltage variation graphs of DC arc plasma during operation of the plasma spraying apparatus according to the first embodiment of the present invention.

As shown in FIG. 4, in the plasma spraying apparatus according to the first embodiment of the present invention, a low voltage electrode and a multi-stage high voltage electrode are serialized using the first positive electrode, the second positive electrode, and the third positive electrode to widen the voltage variation. As a result, there is a greater chance that the particles are completely melted by stably forming a melting zone. Even if both the low-voltage electrode and the high-voltage electrode fail to eliminate voltage variations in the constant current mode, a plasma jet in which the unmelting phenomenon is removed can be obtained. In the plasma spraying apparatus according to the first embodiment of the present invention, a ceramic having a high melting point is melted using an electric power of 30 kW or more, but a dense coating layer is obtained by extending the residence time of the low enthalpy method rather than the high enthalpy method.

In the plasma spraying apparatus according to the first embodiment of the present invention, a low first voltage is applied to the first positive electrode. In addition, relatively high second and third voltages are applied to the second positive electrode and the third positive electrode, respectively. That is, the higher the positive electrode is from the negative electrode, the higher the voltage becomes.

As a result, as shown in FIG. 4 , since a high voltage transition is continuously formed over time, the possibility that the particles included in the suspension are melted and formed into fine particles increases. Therefore, the fine particles may not be melted due to the low applied voltage at a specific time, but as indicated by the solid arrow due to the high voltage transition over time, the particles melt and become fine particles.

More specifically, as shown in FIG. 5 , when the voltage variation of FIG. 4 is divided into a first positive electrode, a second positive electrode, and a third positive electrode, the particles are formed at the first positive electrode, the second positive electrode, and the third positive electrode for a long time. will pass through Therefore, the probability of atomizing and melting particles contained in the suspension is increased three times or more compared to the case where only the first positive electrode is used. That is, in the prior art, as shown in FIG. 3 , in a general plasma spraying apparatus, sparsely high voltage variations are formed over time. Therefore, when the particles contained in the suspension pass through the positive electrode, the possibility of melting is low if a high voltage transition is not applied.

In the plasma spraying apparatus according to the first embodiment of the present invention, since a number of continuous high voltage variations, that is, arc variations, overlap and occur, the coating layer may be formed of fine particles. That is, despite the high voltage variation, the particles receive a large amount of energy from the first positive electrode, the second positive electrode, and the third positive electrode almost simultaneously, and a high-quality coating layer can be manufactured. In contrast to this, in the prior art, large particles are mixed so that the coating layer is not densely formed and may fall therefrom.

6 schematically shows an operation concept of the plasma spraying apparatus 100 of FIG. 1 . The operation concept of the plasma spraying apparatus 100 of FIG. 6 is only for illustrating the present invention, and the present invention is not limited thereto. Therefore, the operating concept may be modified differently.

As shown in FIG. 6 , the first power source 20 is electrically connected to the negative electrode 10 and the first positive electrode 12 , and the second power source 22 is the negative electrode 10 and the second positive electrode 14 . is electrically connected to, and the third power source 24 is electrically connected to the negative electrode 10 and the third positive electrode 16 . That is, the first positive electrode 12 , the second positive electrode 14 , and the third positive electrode 16 are each independently and separately electrically connected to the first power source 20 , the second power source 22 , and the third positive electrode 16 . is connected to Accordingly, voltages may be independently applied to the first positive electrode 12 , the second positive electrode 14 , and the third positive electrode 16 . That is, since the first positive electrode 12 , the second positive electrode 14 , and the third positive electrode 16 are not relay electrodes, a phenomenon in which the arc is cut by the high-pressure gas does not occur. Therefore, suspension may be injected by arranging suspension injection tubes in the spaced spaces 32 , 34 , and 36 located inside the plasma spraying apparatus 100 .

Here, the first power supply 20 forms the primary low voltage DC power, the second power supply 22 forms the secondary high voltage DC power, and the third power supply 24 forms the tertiary high voltage DC power. Accordingly, a voltage higher than that of the first positive electrode 12 is applied to the second positive electrode 14 to form a high voltage section. When the plasma spraying apparatus 100 is started, a first voltage may be applied to the first positive electrode 12 and then a second voltage may be applied to the second positive electrode 14 . The first positive electrode 12 is ignited by an arc start, and the current rises. Conversely, when the plasma spraying apparatus 100 is stopped, the first voltage may be cut off after the second voltage is cut off.

Next, when the helium gas is injected between the negative electrode 10 and the first positive electrode 12, the voltage applied to the negative electrode 10 and the first positive electrode 12 rises, and the helium gas becomes a plasma jet and flows in the direction of the arrow. is formed This flow has a flow velocity from subsonic to Mach. The suspension injected through the suspension injection tube 50 is atomized while forming fine droplets. The fine droplets containing the solvent are injected into the high-temperature plasma jet while passing through the second positive electrode 14 . Then, the solvent is vaporized and the solute solid remains agglomerated and melted.

The remaining fine particles are melted and collided with each other while flying to form molten particles with increased particle size. Therefore, the chance of free movement of the molten particles is reduced and they fly only by the flow velocity of the plasma jet, so that the molten particles can accurately land on the target without loss and form a good quality coating layer. The particle size of the molten particles colliding with the target may be 1 μm to 10 μm.

In addition, the third power source 24 generates a third high voltage DC power somewhat larger than that of the second power source 22 . That is, a higher voltage than the second positive electrode 14 is applied to the third positive electrode 15 to accelerate the flight of the molten particles. That is, since the water injected through the suspension injection pipe 50 passes through the first positive electrode 12 and the second positive electrode 14 and is amplified to a higher temperature in a vaporized state, the movement of the molten particles can be accelerated. That is, since a higher temperature is heated by the third positive electrode 15 in a passage of a certain volume, a large pressure is applied to the molten particles in proportion to this and accelerated. Therefore, the molten particles fly at high speed in the direction of the arrow to improve the adhesion of the coating particles to the substrate. In addition, it is possible to minimize the loss rate of the molten particles by imparting a flight direction to the molten particles.

To this end, in the step of applying the third voltage to the third positive electrode, the third voltage may be adjusted to 1.5 to 2 times the second voltage. If the third voltage is too greater than the second voltage, the molten particles may be burned by the high voltage. Conversely, if the third voltage is similar to or lower than the second voltage, acceleration of the molten particles cannot be expected. Meanwhile, in the step of applying the second voltage to the second positive electrode, the second voltage may be 3 to 4 times the first voltage. Within this range, the atomized particles can be melted.

An insulator may be positioned in the spaced spaces 32 , 34 , 36 , and 38 illustrated in FIG. 6 , or may be left empty. A suspension injection pipe 50 is positioned in the separation space to inject the suspension into the plasma jet flow. A suspension containing alcohol having an ignition calorific value may be supplied through the suspension injection pipe 50 .

The suspension injection tube 50 may be positioned to be spaced apart from each other in a circumferential direction of the plasma spraying apparatus 100 . Although only one suspension injection pipe 50 is illustrated in FIG. 6 , it may be disposed in various forms, and the number thereof is not limited. The installation angle of the suspension injection pipe 50 may also be changed.

Meanwhile, the inner diameter d14 of the second positive electrode 14 is greater than the inner diameter d12 of the first positive electrode 12 . That is, in the second positive electrode 14 , a relatively large space is required to melt fine powder and form molten particles that collide with each other while forming a plasma jet. Therefore, it is preferable to make the inner diameter d14 of the second positive electrode 14 larger than the inner diameter d12 of the first positive electrode 12 .

The inner diameter d12 of the first positive electrode 12 may be 4 mm to 6 mm. In addition, the inner diameter d14 of the second positive electrode 14 may be greater than 6 mm and less than 8 mm. Meanwhile, the inner diameter d15 of the third positive electrode 15 may be 8 mm to 10 mm. More specifically, the inner diameter d12 of the first positive electrode 12 may be 4 mm, the inner diameter d14 of the second positive electrode 14 may be 7 mm, and the inner diameter d15 of the third positive electrode 15 may be 8 mm. .

Within the above range, the ratio of the inner diameter d14 of the second positive electrode 14 to the inner diameter d12 of the first positive electrode 12 is the third positive electrode 15 to the inner diameter d14 of the second positive electrode 14 . ) is greater than the ratio of the inner diameter (d15). More specifically, the ratio of the inner diameter d14 of the second positive electrode 14 to the inner diameter d12 of the first positive electrode 12 is the third positive electrode 15 to the inner diameter d14 of the second positive electrode 14 . It may be 1.3 to 2 of the ratio of the inner diameter (d15) of When this relative ratio is too small, for example, since the inner diameter d15 of the third positive electrode 15 is small, it may be difficult to secure a space through which a large amount of molten particles can escape. In addition, when this relative ratio is too large, the inner diameter d14 of the second positive electrode 14 increases, so that it may be difficult for the particles atomized in the suspension to move linearly in the direction of the arrow.

7 is a graph schematically illustrating a method for manufacturing α-alumina using the plasma spraying apparatus of FIG. 1 . The method for producing α-alumina of FIG. 7 is only for illustrating the present invention, and the present invention is not limited thereto. Therefore, the method for producing α-alumina can be modified differently.

In FIG. 7 , the x-axis represents time (t), and the y-axis represents Gibbs free energy. Therefore, α-alumina is produced according to the phase transformation of an alumina precursor dispersion such as Al(OH) ₃ (aluminum hydroxide) while going from left to right, that is, passing through the first positive electrode, the second positive electrode, and the third positive electrode of the plasma spraying device in turn. can do. When a phase transformation occurs, the change in Gibbs free energy is zero. First, the alumina precursor dispersion injected through the suspension injection pipe passes through the first positive electrode to form a γ phase, passes through the second positive electrode to form a β phase, passes through the third positive electrode to form an α phase, and the Gibbs free energy is gradually increases That is, depending on the calcination temperature, alumina forms a γ phase at around 500° C., and forms an α phase at 1200° C. or higher, so that α-alumina can be produced. α-alumina has a higher density than γ-alumina. That is, the density of γ-alumina is 3.65 g/cm ³ while that of α-alumina is 3.97 g/cm ³ . Since this can lower the thermal conductivity of γ-alumina, it is suitable for directly manufacturing a heat-resistant coating material using the plasma spraying apparatus according to an embodiment of the present invention. This will be described in more detail with reference to FIG. 8 .

8 schematically shows a plasma spraying apparatus 200 according to a second embodiment of the present invention. Since the structure of the plasma spraying apparatus 200 of FIG. 8 is similar to that of the plasma spraying apparatus 100 of FIG. 6 , the same parts are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

As shown in FIG. 8 , suspension injection tubes 501 and 503 are installed in the first positive electrode 12 and the third spaced apart space 36 , respectively. The installation positions of the suspension injection tubes 501 and 503 are merely for illustrating the present invention, and the present invention is not limited thereto.

The suspension injection pipe 501 passes through the first positive electrode 12 and is inserted into a passage through which gas proceeds in the direction of the arrow. For example, since a suspension containing no carbon component and containing water functions as a simple transport agent, it is injected into the first positive electrode 12 . As a result, since the gas starts to be transported from a position close to the plasma jet and has sufficient melting energy, that is, the product of enthalpy and stagnation time for melting particles in the plasma, the coating layer can be well deposited on the target. In addition, a suspension using alcohol, which vaporizes well, as a solvent, may be injected through the suspension injection pipe 503 .

Meanwhile, in some cases, the suspension injection tubes 501 and 503 may be used together. The first material injected through the suspension injection tube 501 and the second material forming the compound are injected through the suspension injection tube 503 . In this case, the difference between the melting point of the first material and the melting point of the second material may be 500° C. or more. By making the injection positions of the first material and the second material different, it is possible to manufacture a high-quality coating material in which the phase is controlled. Of course, only one of the suspension injection tubes 501 and 503 may be selected to inject the suspension.

9 schematically shows a plasma spraying apparatus 300 according to a third embodiment of the present invention. Since the structure of the plasma spraying apparatus 300 of FIG. 9 is similar to that of the plasma spraying apparatus 100 of FIG. 8 , the same parts are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 9 , the suspension injection tubes 501 and 503 are installed in the first positive electrode 12 and the third spaced apart space 36 , respectively. The installation positions of the suspension injection tubes 501 and 503 are merely for illustrating the present invention, and the present invention is not limited thereto.

As shown in FIG. 9 , suspension injection tubes 501 and 505 are installed on the first positive electrode 12 and the outer side 38 , respectively. In this case, suspension plasma spraying by the suspension injection tube 501 and atmospheric plasma spraying by the suspension injection tube 505 may be mixed and used. Therefore, it is possible to freely control the phase of the resulting coating material. Of course, unlike this, only one of the suspension injection tubes 501 and 505 may be used.

Although the present invention has been described as described above, it will be readily understood by those skilled in the art to which the present invention pertains that various modifications and variations are possible without departing from the spirit and scope of the appended claims.

10. Negative Electrode
12, 14, 15. Positive electrode
11, 13, 16, 18, 19. Insulator
14. Second positive electrode
17. Support bar
20, 22, 24. Power part
32, 34, 36, 38. Separation space
50, 501, 503, 505. Suspension injection tube
100, 200, 300. Plasma thermal spraying device
111, 181, 191. Openings
131. Through hole
161. Front
163. Overhang
181, 191. Screwdriver
P. plasma jet

Claims (10)

delete delete delete delete delete i) a first insulator 11 having a plurality of first screw holes 111 formed therein;
ii) the negative electrode 10 accommodated in the first insulator 11 and fixed;
iii) a through hole 131 into which the negative electrode 10 is inserted and fixed, and a second insulator 13 in contact with the first insulator 11;
iv) a third insulator 16 including a protrusion 163 inserted into the through hole 131 and in contact with the second insulator 13;
v) a first positive electrode 12 spaced apart from the negative electrode 10 to form a first separation space 32, a passage is formed therein, and is accommodated and fixed in the third insulator 16;
vi) forming the first positive electrode 12 and the second separation space 34 along the traveling direction of the gas applied to form a plasma jet while being accelerated through the first positive electrode 12, and the first positive electrode 12 A second positive electrode 14 positioned opposite the negative electrode 10 with the
vii) forming a third spaced-apart space 36 that is spaced apart from the second positive electrode 14 and left as an empty space, and the first positive electrode 12 along the traveling direction with the second positive electrode 14 interposed therebetween The third positive electrode 15 located on the opposite side of the
viii) a fourth insulator 18 positioned between the second positive electrode 14 and the third positive electrode 15 and having a plurality of second screw holes 181 formed therein;
ix) a fifth insulator 19 positioned opposite the fourth insulator 18 with the third positive electrode 15 interposed therebetween, and having a plurality of third screw holes 191 formed therebetween;
x) is inserted into the plurality of first screw holes 111 and the plurality of second screw holes 181 , and the negative electrode 10 , the second insulator 13 , and the third insulator 16 . , a pair of first support rods 17 spaced apart from the first positive electrode 12 and the second positive electrode 14 and positioned on the outer periphery thereof;
xi) inserted into the plurality of first screw holes 111 and the plurality of third screw holes 191 , the negative electrode 10 , the second insulator 13 , and the third insulator 16 . , the first positive electrode 12, and the second positive electrode 14 and spaced apart from another pair of first support rods 17 located on the outer periphery;
xii) a first power source 20 electrically connected to the first positive electrode 12;
xiii) a second power source 22 provided separately from the first power source 20 and electrically connected to the second positive electrode 14;
xiv) a third power source 24 provided independently of the first power source 20 and the second power source 22 and electrically connected to the third positive electrode 15
Providing a plasma spraying device 100 in the atmosphere comprising a;
applying, by the first power source 20, a first voltage to the first positive electrode 12;
applying, by the second power source (22), a second voltage greater than the first voltage to the second positive electrode (14);
applying, by the third power source (24), a third voltage greater than the second voltage to the third positive electrode (15);
supplying at least one suspension comprising at least one coating material to the passage at a location in the second spaced-apart space (34), and
A step of vaporizing the solvent included in the droplet while the droplet included in the suspension is atomized by the gas
including,
In the step of providing the plasma spraying device 100 , the first separation space 32 , the second separation space 34 , and the third separation space 36 are outside the plasma spraying device 100 . The control method of the plasma spraying device 100 is in communication with the passage is connected to the outside. delete delete delete In claim 6,
In the step of applying the third voltage to the third positive electrode, the third voltage is 1.5 to 2 times the second voltage,
In the step of applying the second voltage to the second positive electrode, the second voltage is three to four times the first voltage, the control method of the plasma spraying apparatus 100.

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