TW201233449A - Plasma spraying device - Google Patents

Abstract

The subject of this invention is to provide a plasma spray device capable of reducing the surface oxidation of particles becoming molten droplets to form the spray coating film with less oxide. The solution of this invention comprises: a primary gas passage (11), forming a primary gas nozzle (10) at the outer periphery of a cathode (40) and covering the front end part of the cathode (40); a secondary gas nozzle (20) disposed outside the primary gas nozzle (10) and forming a secondary gas passage (21); and a tertiary gas nozzle (30) forming a tertiary gas passage (31) between the primary gas nozzle (10) and the secondary gas nozzle (20). The tertiary gas passage (31) receives the thermal jet of plasma flame (F) at the outer periphery part of the plasma flame (F) to become a tertiary gas of high temperature gas jet.

Description

201233449 VI. Description of the Invention: [Technical Field] The present invention relates to an electric paddle coating device that moves a plasma arc to a conductive wire to generate a plasma flame while ejecting the wire while spraying . [Prior Art] Fig. 7 is a cross-sectional view of a conventional plasma spraying device. As shown in Fig. 7, the conventional plasma spraying device 90 includes a primary gas nozzle 91 that forms the primary gas passage 91a, and a secondary gas nozzle 92 that is disposed on the side of the primary gas nozzle 91 to form the secondary gas passage 92a. The nozzle 93 of the primary gas nozzle 91 and the cathode 93 on the substantially central axis of the nozzle 92a of the secondary gas nozzle 92; the power supply device 94; and the vicinity of the nozzle opening 92a of the secondary gas nozzle 92 supply the electroconductive wire for spraying Wire guide hole 95 of W. The wire W is supplied obliquely forward from the wire guiding hole 95 toward the central axis of the nozzle opening 92a. Further, the primary gas sprayed from the primary gas passage 9 1 a is caused to be indirectly connected between the wire W on 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. The arc is plasmated to become a plasma flame, and the wire W is sprayed by the droplet D. The droplet D is further refined by the secondary gas injected from the secondary gas passage 92a toward the front of the secondary gas nozzle 92, and is accelerated to be sprayed onto the workpiece τ to form the spray film S. When the conventional plasma spraying device 90 shown above is used as the above-mentioned conventional plasma spraying device 90, the primary gas is an inert gas such as nitrogen gas or argon gas, twice. As the gas, a gas such as compressed air, a nitrogen gas, or a carbonic acid gas is used (for example, refer to Patent Document 1). However, in actual use, in terms of secondary gas, low-cost compressed air is utilized because of the high operating cost of nitrogen gas and carbonic acid gas. In the plasma spraying apparatus 90, the primary gas to be pulverized is surrounded by the compressed air of the secondary gas, whereby the primary gas of the plasma can be sprayed, and the speed of the primary gas can be increased. [Patent Document 1] Japanese Laid-Open Patent Publication No. Hei 9-30897-A No. JP-A No. Hei 9-30897-A. SUMMARY OF THE INVENTION However, in the conventional plasma spraying apparatus 90, the droplet D of the molten metal wire W is thinned by the spraying of the secondary gas. Further, in order to impart a sufficient speed to each of the droplets D, the metal material in the spray coating S is disturbed in the outer periphery of the plasma flame F because the compressed air of the secondary gas at the time of melting rapidly enters. Therefore, the surface of the particles of the droplet D is oxidized, and the sprayed coating S contains an oxide of a metal material. Accordingly, it is an object of the present invention to provide a plasma spraying apparatus which forms a sprayed film having less oxide by reducing oxidation of the surface of the particles which become droplets. A plasma spraying apparatus according to 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 an end portion of the cathode; and is disposed outside the primary gas nozzle to form a secondary gas passage

S -6- 201233449 secondary gas nozzle; and a wire passage for supplying a wire for spraying near the nozzle opening of the secondary gas nozzle, using a tip end of the wire supplied from the wire passage and the cathode The generated arc, the primary gas injected by the primary gas nozzle is plasmad, and a plasma flame sprayed by the primary gas nozzle is formed to make the front end of the wire become a droplet, and then sprayed by the plasma flame and the secondary gas nozzle. The secondary gas is sprayed onto the plasma spraying device on the workpiece, and between the primary gas nozzle and the secondary gas nozzle, the peripheral portion of the plasma flame is provided with: It is a tertiary gas nozzle that takes the heat of the plasma flame and becomes the tertiary gas passage of the tertiary gas for the purpose of high-temperature gas injection. According to the plasma spraying apparatus of the present invention, the heat of the plasma flame is received from the inside of the three gas streams ejected from the three gas passages disposed between the primary gas passage and the secondary gas passage to form a high-temperature gas injection. By the high-temperature gas injection, when the secondary gas injected on the outside is rapidly mixed, the disturbance occurring from the outer periphery of the plasma flame is suppressed, and since the diffusion of the plasma flame is prevented, the particle surface to be the droplet can be reduced. Oxidation. Here, as the tertiary gas, compressed air, carbonic acid gas or the like can be used. However, it is preferable to use an inert gas such as argon gas or nitrogen gas for the tertiary gas. When the inert gas is used for the tertiary gas, the rapid intrusion of the secondary gas is prevented, and the disturbance occurs from the outer periphery of the plasma flame, and, in the outer periphery of the plasma flame, the heat of the plasma flame is formed to become the inertia of the high temperature. Gas injection. Thereby, the particles of the droplet can be prevented from being oxidized by the secondary gas because they are refined and accelerated in the inert gas injection at a high temperature. Further, in the plasma spraying apparatus of the present invention, even when the primary gas uses 201233449 compressed air, it is possible to form a compressed air for the sprayed skin which is less oxidized, and the primary gas contains about 20% of the body to be pulverized and melted. The oxidation of metal as a primary gas should reduce the spray. However, in the conventional plasma spraying device, when the plasma flame is disturbed by the second time, the oxidation of the droplet will use compressed air when the gas is used. In the plasma spraying apparatus of the present invention, the plasma spraying device of the present invention is formed by using the heat of the plasma flame in the peripheral portion of the three flames, because the secondary gas can be prevented from rapidly entering and moving, even if the primary gas uses compressed air. The film can also be sprayed. (1) By having a tertiary gas nozzle for injecting a three-passage for the purpose of jetting a gas which is heated to a high temperature in the outer periphery of the plasma flame, it is possible to prevent the plasma flame from being The surface of the droplets is oxidized to form an oxide film. (2) When the inert gas is used for the tertiary gas, the heat generated by the plasma flame is formed in the portion to become a high temperature. The particles which are droplets are prevented from being oxidized by the secondary gas in the high-temperature inert gas injection, so that it can be formed. Coating the film. (3) - Three membranes when compressed air is used for secondary gas. The primary gas makes oxygen, however, the gas is of course reduced, so the oxidation of the coating film. The rapid mixing of the gas is excessively carried out, so that it is lowered. The other gas is irritated by the gas jet plasma flame at the high temperature of the plasma fire to form the third gas nozzle which is less oxidized, and is diffused by the three gases of the plasma flame gas, thereby reducing the spray plasma flame of the product. Excessive gas injection, due to miniaturization, acceleration, oxides, and less, the gas will also be in the electricity -

S 201233449 The outer peripheral part of the slurry flame forms a gas which is subjected to the heat of the plasma flame and becomes a high temperature, thereby preventing the disturbance of the plasma flame caused by the rapid mixing of the secondary gas, so that a spray film having less oxidation can be formed. [Embodiment] Fig. 1 is a schematic structural view of a plasma spraying apparatus according to an embodiment of the present invention, and Fig. 2 is a detailed longitudinal sectional view of a main part of a plasma flame moment of Fig. 1, and Fig. 3 is a Fig. 2 is a diagram showing the arrow direction of Fig. 4, and Fig. 4 is an explanatory diagram of the operation of the plasma flame moment of Fig. 1. In the first embodiment, a plasma spraying apparatus 1 according to an embodiment of the present invention has a plasma spraying torch 2 for spraying a wire W which becomes a droplet due to a plasma flame onto a workpiece; Spraying the fire moment 2 to supply the gas supply source 3 of the primary gas and the secondary gas; the power supply 4 for supplying the operating power to the plasma spraying torch 2; the wire reel 5 for winding the wire W; for correcting the wire reel A wire straightening machine 6 for the crimping habit of the drawn wire W; and a wire supplying mechanism 7 for supplying the wire W to the plasma spraying torch 2 by the wire stepping tube 8. As shown in Fig. 2, the plasma spraying torch 2 includes a primary gas nozzle 10 forming a primary gas passage 11, and a secondary gas nozzle 20 disposed outside the primary gas nozzle 10 to form a secondary gas passage 21; The tertiary gas nozzle 30 disposed between the primary gas nozzle 10 and the secondary gas nozzle 20 to form the tertiary gas passage 31 is disposed at substantially the center of the nozzle opening 12 of the primary gas nozzle 1 and the nozzle opening 22 of the secondary gas nozzle 20. The cathode 40 on the shaft; and the nozzle opening 22 of the secondary gas nozzle 20 are attached to the wire passage 50 of the coating wire W. The primary gas nozzle 10 is formed to cover the front end of the cathode 40, and a primary gas passage is formed on the outer circumference of the cathode 40. The primary gas supplied to the primary gas passage 11 is an inert gas such as nitrogen gas or argon gas for the purpose of generating an electric flame and causing the front end of the wire to be a droplet. Alternatively, compressed gas may be used as the primary gas. The primary gas supplied from the primary gas passage 11 is supplied so as to bypass the outer circumference of the cathode, and is ejected from the nozzle opening of the primary gas nozzle 10 toward the front of the secondary gas nozzle 20. The tertiary gas nozzle 30 is formed to surround the primary gas nozzle 1 ,, and the gas passage 31 is formed three times outside the primary gas nozzle 10. The tertiary gas is a gas for the purpose of gas injection in which the heat of the plasma flame is generated in the outer peripheral portion of the plasma flame and is a high-temperature gas injection, and is a gas such as compressed air or carbonic acid gas. The two gas nozzles 20 are formed to surround the outer side of the tertiary gas nozzle 30, and a secondary gas flow path 21 is formed on the outer periphery of the tertiary gas nozzle 30. The secondary gas is sprayed in such a manner that the jet flame formed by the primary gas is rapidly mixed in from the outside, so that the droplet becomes fine and the droplet has a sufficient speed to be ejected onto the workpiece. The gas is a gas such as compressed air or carbonic acid gas. The primary gas is preferably in the range of 50 to 120 (minutes) because the temperature, velocity, and voltage of the plasma are moderately changed by the change in the gas flow rate. Moreover, when the flow rate of the primary gas is 50 (L/min or less, the speed of the plasma flame is slow, which will result in the quality of the sprayed film, and the shape of the slurry on the side of the slurry 12 is the second generation of the body. drop

S -10- 201233449 ' Low. On the other hand, when the flow rate of the primary gas exceeds 120 (L/min), the speed of the plasma flame is too fast, and the temperature is lowered to cause a decrease in the quality of the sprayed coating. The secondary gas, as described above, is once from the outside. The jet of the plasma flame formed by the gas is sprayed in such a manner as to be rapidly mixed, so that the droplet is refined and the speed of the droplet is sufficient, so that the flow rate is preferably 250 to 500 (L/min). Further, when the flow rate of the secondary gas is 250 (L/min) or less, the droplet refinement is insufficient, or the effect of imparting the speed of the droplet filling is reduced, resulting in deterioration of the quality of the spray coating. On the other hand, when the flow rate of the secondary gas exceeds 500 (L/min), the droplets are too fine and the droplets are excessively cooled, resulting in deterioration of the quality of the spray coating. The tertiary gas, as described above, is formed into a high-temperature gas jet in order to form a high-temperature gas jet in the outer peripheral portion of the plasma flame generated by the primary gas, so that the volume ratio should be 20 to 50% of the flow rate of the primary gas. In addition, in order to suppress the disturbance of the plasma flame and the gas diffusion caused by the secondary gas injection, the volume ratio is preferably in the range of 5 to 10% of the flow rate of the secondary gas. Further, in order to effectively exert the effect of suppressing the disturbance of the plasma flame and the gas diffusion caused by the secondary gas injection, the flow rate of the tertiary gas is changed in conjunction with the increase or decrease of the flow rate of the secondary gas, so that the flow rate of the secondary gas When there are few, the flow rate of the tertiary gas is also small, and when the flow rate of the secondary gas is large, the flow rate of the tertiary gas is also large. Moreover, the flow rate of the tertiary gas is less than 20% of the flow rate of the primary gas, or the flow rate of the secondary gas is less than 5%, because the injection of the tertiary gas - the effect of suppressing the disturbance of the plasma flame and the gas diffusion is less, and it is not easy Get the effect of -11 - 201233449 liter spray film quality. On the other hand, when the flow rate of the tertiary gas exceeds 50% of the flow rate of the primary gas or exceeds 1% of the flow rate of the secondary gas, the plasma gas is formed on the inner side due to the injection of the stronger tertiary gas. When the heat is high and the gas is injected at a high temperature, the effect of suppressing the disturbance of the plasma flame and the gas diffusion cannot be sufficiently exerted, and it is difficult to obtain an effect of improving the quality of the sprayed film. The wire passage 50 is composed of a primary wire passage 5 1 a having a wire outlet 5 1 b formed in the vicinity of the nozzle opening 2 2 of the secondary gas nozzle 20; and specific to the primary wire passage 5 1 a The inclination angle Θ is supplied by the secondary wire passage 5 2 a of the wire W. The wire passage 50 is a primary wire passage 5 1 a and a secondary wire passage 5 2 a, and the wire W is bent to a range not exceeding the elastic limit. As shown in Fig. 3, the primary wire passage 51a has a slightly rectangular cross-sectional shape in which the plasma flame extends in a long direction, so that the primary wire guiding member 5 disposed outside the secondary gas nozzle 20 is provided. 1 is formed in a straight line. Similarly, the secondary wire passage 52a also has a slightly rectangular cross-sectional shape in which the plasma flame extends in a long direction, so as to guide the secondary wire disposed at a position away from the primary wire passage 51a. The member 52 is formed to penetrate in a straight line. The width a of the primary wire passage 51a in the longitudinal direction is set to a range of 10% or more and 95% or less of the diameter d of the wire W. Further, the width b of the primary wire passage 5 1 a in the short-side direction is set to be smaller than the diameter d of the wire W by 3% or more and less than 1 〇 %. Further, the diameter d of the wire W of the present embodiment is 1.6 mm'

S -12- 201233449 'The width a of the longitudinal direction is set to be larger than the diameter d of the wire W by 0.2 to 1. The width of the short side direction is set to be larger than the diameter d of the wire W by 0 to 5 mm. 〇5~0 · 1 5 mm size. The same is true for the secondary wire passage 52a. Further, the primary wire passage 5 1 a and the secondary wire passage 5 2 a have a substantially rectangular cross-sectional shape, and the rectangular cross-sectional shape is not included in the corner portion of the rectangular cross-sectional shape and does not contact the outer surface of the wire W. The range of processing such as C-face chamfering and R-face chamfering is performed in the range. However, in the wire W of the present embodiment, any plane in the plane of the longitudinal direction or the plane of the short side direction in the primary wire passage 5 1 a and the secondary wire passage 52a receives only the force in the vertical direction. Further, the inclination angle Θ of the secondary wire passage 52a with respect to the primary wire passage 5 1 a is the angle between the center line of the primary wire passage 5 1 a and the center line of the secondary wire passage 52a. In the present embodiment, the tilt angle Θ is set to about 1 to 5 degrees. Further, the secondary wire guiding member 52 is disposed at a position spaced apart from the primary wire passage 51a and the secondary wire passage 52a by a gap c therebetween. In the present embodiment, the gap c is set to about 3 to 10 mm. When the plasma spray flame 2 of the present embodiment as described above is disposed, the primary wire passage 5 1 a and the secondary wire passage 52 a are disposed with a gap c interposed therebetween, and the primary wire passages are linearly arranged. The 5 1 a and secondary wire passages 52 a are formed into a wire passage 50 which is shaped like a large curve, and the wire W is given a bending which does not exceed the range of the elastic range. Further, the primary wire passage 5 1 a and the secondary wire passage 52a ' may be the anode side of the power supply 4 of the curve -13 - 201233449, respectively, and are connected to the primary wire guiding member 5 1 and indirectly connected. The wire W passing through the primary wire passage 5 1 a of the primary wire guiding member 51 is passed. On the other hand, the cathode side of the power source 4 is connected to the cathode 40. Further, the anode side of the power source 4 may be directly connected to the wire W. In the plasma spraying apparatus 1 of the above configuration, when the wire W wound around the wire reel 5 is fed by the wire supplying mechanism 7 to the plasma spraying torch 2, the wire straightening machine 6 performs strong crimping of the wire W. The correction of habits causes it to stretch into a gentle curve. Further, the wire W is supplied to the wire passage 50 via the metal wire stepping tube 8. In the wire passage 50 and the wire W, only the plane in the longitudinal direction of the primary wire passage 5 1 a and the secondary wire passage 52a or the plane in the short side direction receives the force in the vertical direction. As shown in Fig. 4, the bending in the range in which the direction of elongation of the plasma flame F does not exceed the elastic limit is given. Here, the primary wire passage 51a and the secondary wire passage 52a have a substantially rectangular cross-sectional shape in which the direction in which the plasma flame F extends is long, and the curling behavior is stretched toward the extending direction of the plasma flame 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 by 3% or more and less than 10%, so that it does not face the plasma flame F. Stretch in the direction of the right angle of the stretch. Therefore, the front end portion of the wire W, relative to the direction in which the plasma flame F is stretched, can be prevented from being displaced in a direction perpendicular to the direction of elongation of the electric prize flame F even when a certain positional shift occurs, and is located in the plasma. Flame Ft

S -14 - 201233449 on the axis. Figure 5 is the cross-sectional shape of the wire passage and the direction of the force the wire is subjected to. In Fig. 5, the substantially rectangular cross section A has a rectangular cross-sectional shape, a substantially rectangular cross-section B, and a C-side chamfered shape in a corner portion of the rectangular cross-sectional shape that does not contact the outer surface of the wire W, and has a substantially rectangular cross-section C. The shape of the corner portion of the rectangular cross-sectional shape is subjected to R-face chamfering in a range where the outer surface of the wire W is not in contact with the surface. In the case of the substantially rectangular cross-sectional shape, the wire W receives only the force in the vertical direction with respect to each plane regardless of whether it is in contact with the plane of the long side direction or the plane of the short side direction. The wire W cannot be completely corrected in a straight line by the wire correcting mechanism 7, and has a curling habit. Further, the wire stepping tube 8 does not have a constant shape due to the treatment of the plasma spray flame 2 during the operation, resulting in a change in the shape of the bend in various states. Therefore, if the wire W having a curling property which does not necessarily have a shape is conveyed in the wire stepping tube 8, the bending and torsion force in accordance with the shape of the wire stepping tube 8 acts on the wire W. By the bending and torsion forces, the wire W is freely bent in the same manner as the spring within the elastic limit, and is in a stable position in the direction of the force, and is snaked in the wire stepping tube 8 to be conveyed. At this time, in the substantially rectangular cross-sectional shape described above, when the wire W contacts the plane in the short-side direction, it receives the vertical direction with respect to the plane of the short-side direction, that is, the direction in which the plasma flame F is stretched ( Hereinafter, the force called "'X direction"), the curling habit stretches toward the stretching direction of the plasma flame F. Further, when only the plane in the short-side direction is received and the force in the direction perpendicular to the direction of extension of the plasma flame F of -15-201233449 (hereinafter referred to as rY direction) is received, the wire W is on the short side. The gap portion of the width b of the direction is freely moved, and although it is in contact with the plane in the longitudinal direction, at this time, the position of the wire W is caused by the force in the vertical direction (Y direction) with respect to the plane of the longitudinal direction. In stability. In particular, when the force of the torsion is applied, the forces in the X direction and the Y direction are dispersed into the forces in the short side direction and the long side direction, and the force acts on the respective surfaces in the vertical direction, thereby suppressing the twist of the wire W, so the metal The position of the wire W is stable. On the other hand, in the case of a circular cross section and an elliptical cross section, when the wire W contacts the curved surface of the circular cross section and the elliptical cross section, only the force in the vertical direction with respect to the curved surface is received, and the wire w can freely move along the curved surface. . In particular, when the force of the twist is applied, the wire W is freely rotated along the curved surface without suppressing the twist of the wire W. Therefore, the direction of the force of the wire W is not necessarily the same, so the position of the wire w is unstable. Therefore, in the plasma spraying device 1 of the present embodiment, the front end portion of the wire W can be used for the plasma flame. The center of the F is supplied with the wire W in a stable manner. Further, the primary gas generated by the primary gas passage 11 is indirectly connected to the anode W side of the power source 4 via the primary wire guiding member 51, and the cathode 40 connected to the cathode side of the power source 4. The arc generated between them is plasmated to become a plasma flame F' and the wire W is sprayed by the droplet D. The droplet D is made finer by the secondary gas injected from the secondary gas passage 21 toward the front of the secondary gas nozzle 20, and is more rapidly ejected onto the workpiece T to form the spray coating S.

S -16-201233449 At this time, the plasma spraying apparatus 1 of the present embodiment is formed inside the three-phase gas flow injected from the tertiary gas passage 31 disposed between the primary gas passage 11 and the secondary gas passage 21. The gas jet G is heated to a high temperature by the heat of the plasma flame F. By the high-temperature gas injection G, it is possible to suppress the disturbance of the secondary gas injected on the outer side and the disturbance occurring in the outer portion of the plasma flame F, thereby preventing the gas diffusion of the plasma flame F and reducing the dissolution. Oxidation of the surface of the particles of D. Thereby, the spray coating film S having less oxidation on the workpiece T can be formed. Further, in the plasma spraying apparatus 1 of the present embodiment, since the heat of the plasma flame F is formed in the peripheral portion of the plasma flame F by the tertiary gas to be a high-temperature gas injection, the rapidity of the secondary gas is prevented. The disturbance of the plasma flame F caused by the mixing is formed, and even if the primary gas uses compressed air, the sprayed film S having less oxidation can be formed. Further, when the nitrogen gas of the inert gas and the argon gas are used for the tertiary gas, as described above, not only the disturbance occurring in the peripheral portion of the plasma flame F caused by the rapid mixing of the secondary gas but also the plasma can be prevented. The outer peripheral portion of the flame F forms an inert gas jet which is subjected to the heat of the plasma flame F to become a high temperature. As a result, the particles of the droplet D are prevented from being oxidized by the secondary gas in a state where the particles of the droplets are prevented from being changed by the high-temperature inert gas. Thereby, the spray coating 72 having less oxidation can be formed. Further, in the present embodiment, both of the primary wire passage 51a and the secondary wire passage 52a have a substantially rectangular cross-sectional shape in which the direction in which the plasma flame extends is long. However, only one of them may have -17 - 201233449 There is a roughly rectangular cross-sectional shape in which the plasma flame extends in a long direction. At this time, the primary wire passage or the secondary wire passage having a substantially rectangular cross-sectional shape in which the plasma flame extends in a long direction is used to stretch the curling habit of the wire W toward the stretching direction of the plasma flame F. The front end portion of the wire W is supplied to the center portion of the plasma flame F. [Examples] A comparative test was carried out when a nitrogen gas of compressed air and an inert gas was used for three times of gas, and when three gases were not used. In the present embodiment, an aluminum-based alloy was used as the coating material, and the natural potential of the sprayed coating was measured as an index of the degree of oxidation of the sprayed coating to confirm the effect of the tertiary gas. Further, in the method of reducing the operating cost, all of the primary gas, the secondary gas, and the tertiary gas are sprayed with inexpensive compressed air, and the natural potential of the sprayed coating is measured to confirm the effect of the third gas. Fig. 6 is an explanatory diagram of a method for measuring a natural potential. The measurement of the natural potential shown in Fig. 6 is carried out by using a salt bridge of saturated KC1 to create a 5w% NaCl environment on the surface of the sprayed film of the test piece (test TP), and using a saturated silver chloride electrode for the comparison electrode. Natural potential. Further, in order to stabilize the measured number of potentials, the potential after 600 seconds from the start was measured as the measurement enthalpy. The test results are summarized as shown in Table 1. The results of the measurement of the natural potential of the film of each condition of Table 1 are shown in Table 2.

S -18 - 201233449 [Table i] The potential of the film of the three gas conditions is three times when the gas is used for nitrogen gas -1150 (-1196 ～1106) mV. When the compressed gas is used for three times, the gas is -1063 (-1080 ～-1032) mV, When the compressed air is used for the secondary and tertiary gases -1052 (-1069 ~ -1020) mV. The traditional three-gas is not used -997 (-1019 ~-980) mV. Typical spraying conditions. Primary gas flow: nitrogen gas = 70 (1/min) Secondary gas flow: compressed air = 400 (1/min) Three gas flow: compressed air and nitrogen gas = 30 (1/min) Film thickness: 1 〇〇 (±20) μιη Voltage generation: 130(±5)(V) Current generation: 60(±1)(A) Material of spray wire: 5% magnesium, 95% aluminum alloy (mass ratio) -19- 201233449 [Table 2] Table 2 The natural potential measurement result of the film of the condition is the primary gas flow rate ΐ k, the volume of the secondary gas flow of the body type 1 M. The average potential of the potential film of the three-dimensional gas tensor film of the body type Remarks 1-1 Nitrogen 70 Air 400 Nitrogen 30 - 1194 -1150 The shielding effect of nitrogen secondary gas 120 500 25 -1142 70 400 20 -1196 70 400 35 -1106 Upper limit 100 250 22 -1114 1-2 Nitrogen 100 Air 500 Nitrogen 20 -1005 Out of range less than 5% 70 400 40 -921 /jcjcrsi More than 50% outside the range 50 250 35 -894 Outside the range exceeds the upper limit 値 2-1 Nitrogen 70 Air 400 Air 30 -1080 -1063 Mixing effect of three gases of air 120 500 40 -1074 70 400 20 -1065 Lower limit 70 400 35 -1032 Upper limit 100 250 22 -1062 2-2 Nitrogen 100 Air 500 Air 20 -924 Out of range less than 5% 70 400 40 -876 Out of range 50% 50 250 35 -894 Out of range exceeds upper limit 値3 Air 70 Air 400 Air 30 -1069 -1052 3 When all the gases are air, the mixing effect of the three gases is 120 500 40 -1063 70 400 20 -1052 Lower limit 70 400 35 -1055 Upper limit 100 250 22 -1020 4 Nitrogen 70 Air 400 Ant. Pick 0 -984 -997 Secondary gas 120 500 0 -997 100 400 0 -1019 70 500 0 -1005 100 250 0 -980 -20- 201233449 . As shown in Table 1, when three gases are not used and compressed air is used as the tertiary gas, compression is used. air For the three gases, presenting a low potential of about 60mV. Further, when a nitrogen gas of an inert gas was used as the tertiary gas, a low enthalpy of about 150 mV was exhibited. Also, when all of the gas uses a cheap compressed air, it exhibits a low enthalpy of about 5 OmV. As a result, it has been confirmed that the plasma spraying apparatus of the present invention can be reduced by the use of the tertiary gas. 6 The plasma spraying apparatus of the present invention is useful for forming a coating film for preventing rust on the surface of a steel structure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the structure of a plasma spraying apparatus according to an embodiment of the present invention. Fig. 2 is a detailed longitudinal sectional view showing the main part of the plasma spray flame of Fig. 1. Fig. 3 is a diagram showing the direction of the arrow A of Fig. 2, and Fig. 4 is an explanatory diagram of the operation of the plasma spraying torch of Fig. 1. Fig. 5 is a cross-sectional view of the cross-sectional shape of the wire passage and the direction of the force to which the wire is taken. Fig. 6 is an explanatory diagram of a method for measuring a natural potential. Figure 7 is a cross-sectional view of a conventional plasma spraying device. [Main component symbol description] 1 : Plasma spraying device 2 : Plasma spraying fire moment - 21 - 201233449 3 : Gas supply source 4 : Power supply 5 : Wire reel 6 : Wire straightening machine 7 = Wire supply mechanism 1 〇 : - Secondary gas nozzle 11 : Primary gas passage 1 2 : Nozzle opening 20 : Secondary gas nozzle 21 : Secondary gas passage 22 : Nozzle opening 30 : Third gas nozzle 31 : Third gas passage 40 : Cathode 5 0 : Wire passage 5 1 : - secondary wire guide. lead member 5 1 a - secondary wire passage 52 : secondary wire guiding member 5 2 a : secondary wire passage

S -22-

Claims (1)

201233449 VII. Patent application scope: 1. A plasma spraying device, comprising: a cathode; forming a gas passage outside the cathode and covering a primary gas nozzle at a front end of the cathode; and being disposed outside the primary gas nozzle And forming a secondary gas nozzle of the secondary gas passage; and a wire passage for supplying the coating wire to the vicinity of the nozzle opening of the secondary gas nozzle; and the front end of the wire supplied by the wire passage And an arc generated between the cathode and the cathode, wherein the primary gas injected by the primary gas nozzle is plasma-formed to form a plasma flame injected by the primary gas nozzle to make the front end of the wire become a droplet. a plasma spraying device for spraying the droplet onto the object to be treated by the plasma flame and the secondary gas injected from the secondary gas nozzle, wherein: the primary gas nozzle and the secondary gas nozzle Between the outer portion of the plasma flame is formed with a heat that can withstand the plasma flame and sprays a high-temperature gas spray Three gas nozzles for three gas passages of three gases. 2. The plasma spraying device according to claim 1, wherein the volume of the tertiary gas is 20 to 50% of the flow rate of the primary gas and 5 to 10% of the flow rate of the secondary gas. . 3. The plasma spraying apparatus according to claim 1, wherein the third gas is compressed air or carbonic acid gas. - 4. The plasma spraying device of claim 2, wherein the third gas in -23-201233449 is compressed air or carbonic acid gas. 5. The plasma spraying apparatus of claim 1, wherein the third gas is an inert gas. 6. The plasma spraying apparatus according to claim 2, wherein the third gas is an inert gas. 7. The plasma spraying apparatus according to any one of the preceding claims, wherein the primary gas is compressed air. S -24-