TW201544193A - Film formation apparatus - Google Patents

Abstract

The present invention provides a film formation apparatus employing cold spray method, which is capable of uniformizing powder amount adhered on inner walls of passages to which the power pass through. The film formation device comprises a gas powder mixing part 10 for mixing a gas and a powder and supplying them to a nozzle 5, a gas chamber 11 connected to the gas powder mixing part 10 via at least one gas passing opening 13a and introducing the gas into the gas powder mixing part 10, a powder supplying tube 12 for supplying the powder to the gas powder mixing part 10, which penetrates the gas chamber 11 and is disposed such ethat an injection opening 12a protrudes in the gas powder mixing part 10 and toward a front direction of the nozzle 5, and a commutating part 14 provided around the powder supplying tube 12 within the gas chamber 11, for commutating the gas introduced to the gas chamber 11 and allows it to pass the gas passing opening 13a.

Description

Film forming device

The present invention relates to a film forming apparatus using a cold spray method.

In recent years, a cold spray method is known as a method of forming a metal film (see, for example, Patent Document 1). The cold spray method is a method of forming a film on the surface of a substrate by spraying a powder of the material from a nozzle together with an inert gas in a state below the melting point or the softening point, and directly impinging on the substrate in a solid phase state. In the cold spray method, since the processing is performed at a lower temperature than the sputtering method, a metal film having no phase change state and oxidation is also suppressed. Moreover, the influence of thermal stress can also be alleviated. Further, when the material of the substrate and the film is a metal, when the powder of the metal material collides with the substrate (or the film formed first), plastic deformation occurs between the powder and the substrate to obtain an anchoring effect. Further, since the oxide film of each other is broken and metal bonds are formed between the new faces, a laminate having high adhesion strength can be obtained.

In the film forming apparatus using the cold spray method as described above, generally, a gas powder mixing portion is provided upstream of the nozzle, and powders and high pressure gases respectively supplied from other systems are introduced into the gas powder mixture. And mix them. Then, the powder is sent from the gas powder mixing portion to the nozzle by the gas pressure of the high pressure gas, and is ejected from the tip end of the nozzle.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2008-302311

However, in the above-described general film forming apparatus, there is a problem in that the powder adheres to the inner wall of the passage when the powder passes through the gas powder mixing portion. Therefore, powder is deposited in a specific portion of the inner wall, and film formation must be interrupted, the gas powder mixing portion and the nozzle are taken out from the film forming apparatus body, and the powder passage is frequently cleaned.

The present invention has been made in view of the above circumstances, and an object of the invention is to provide a film forming apparatus which can uniformize the amount of powder adhering to the inner wall of a passage through which a powder passes through a film forming apparatus using a cold spray method.

In order to solve the above problems and achieve the object, the film forming apparatus of the present invention sprays a powder of a material together with a gas from a nozzle, and directly deposits the powder in a solid phase state and deposits it on the surface of the substrate, thereby forming a film. The film forming apparatus includes: a gas powder mixing unit that mixes the gas with the powder and supplies the gas to the nozzle; and the gas chamber communicates with the gas powder mixing unit through at least one gas passage port to pass the gas Introduced to the gas powder mixing section; the powder supply pipe The powder is supplied to the gas powder mixing portion, and penetrates into the gas chamber, and the injection port of the powder protrudes from the gas powder mixing portion and is disposed toward the tip end of the nozzle; and the rectifying portion is disposed in the gas chamber Around the powder supply pipe, the gas introduced into the gas chamber is rectified and passed through the at least one gas passage port.

In the above film forming apparatus, the rectifying portion has a tubular member having an opening at both ends, and is disposed such that an opening surface of one of the members abuts against the at least one gas passage opening, and the other opening surface faces the opposite side The inner wall of the aforementioned gas chamber.

In the film forming apparatus, an area of the opening surface of the other side that is introduced into the gas chamber into the region where the gas flows in is an area A, and the inner wall is opposed to the opening surface of the other side. The distance to the opening surface of the other side is set to a height, and when the area of the side surface of the columnar shape in which the area is the bottom surface is the area B, the area B is equal to or larger than the area A.

In the above film forming apparatus, the area B is 8 times or less of the area A.

In the film forming apparatus described above, the rectifying portion further includes a plurality of rectifying members provided on an inner wall surface of the tubular member.

In the film forming apparatus described above, the opening surface of the rectifying portion is formed into a shape similar to a cross section orthogonal to the longitudinal direction of the gas powder mixing portion.

In the above film forming apparatus, the opening surface of the rectifying portion is formed to have a cross section orthogonal to the longitudinal direction of the gas powder mixing portion. The same shape.

In the film forming apparatus described above, the opening surface of the rectifying portion is formed into a circular shape, an elliptical shape, a rectangular shape, or a polygonal shape.

According to the present invention, a gas powder mixing portion that allows the gas introduced into the gas chamber to be rectified and passed through the gas passage opening is provided around the powder supply pipe in the gas chamber. The inner wall powder is homogenized. As a result, the frequency of cleaning the powder passage can be reduced, and film formation can be performed efficiently.

1‧‧‧ film forming device

2‧‧‧ gas heater

3‧‧‧Powder supply device

4‧‧‧ spray gun

5‧‧‧ nozzle

6, 7‧‧‧ valve

10‧‧‧Gas Powder Mixing Department

11‧‧‧ gas chamber

12‧‧‧Powder supply tube

12a‧‧‧shots

13, 30‧‧‧Powder Supply Pipe Support Department

13a, 30a‧‧‧ gas passage

13b‧‧‧ openings

14, 40‧‧ ‧ Rectifier

14a‧‧‧Open face

15‧‧‧Temperature Sensor

16‧‧‧ Pressure Sensor

17‧‧‧ gas supply road

20‧‧‧ Columnar area

31‧‧‧ peripheral ring

32‧‧‧Support rod

41‧‧‧ Tube

42‧‧‧Rectifying fins

100‧‧‧Substrate

101‧‧‧ film

111, 121, 122‧‧‧ areas

Fig. 1 is a schematic view showing the configuration of a film forming apparatus according to an embodiment of the present invention.

Fig. 2 is an enlarged cross-sectional view showing the inside of the coating gun shown in Fig. 1.

Fig. 3 is an enlarged plan view showing the support portion of the powder supply pipe shown in Fig. 2.

Fig. 4 is an X-ray view of the rectifying portion shown in Fig. 2.

Fig. 5 is an enlarged perspective view showing the vicinity of the opening surface of the flow regulating portion shown in Fig. 2;

Fig. 6 is a plan view showing a modification of the powder supply tube support portion shown in Fig. 2.

Fig. 7 is a perspective view showing a modified example of the rectifying portion shown in Fig. 2.

Figure 8 is a view showing that the rectifying portion shown in Fig. 7 is attached to a spray gun. A sectional view of the state.

Fig. 9 is a photograph showing a gas powder mixing portion after the experiment of Example 2.

Fig. 10 is a photograph showing a gas powder mixing portion after the experiment of Comparative Example 2.

Hereinafter, the present embodiment will be described in detail with reference to the drawings. Further, the present invention is not limited to the following embodiments. Moreover, the drawings referred to in the following description merely schematically illustrate the shape, size, and positional relationship of the extent to which the present invention can be understood. That is, the present invention is not limited to the shapes, sizes, and positional relationships illustrated in the respective drawings.

(embodiment)

Fig. 1 is a schematic view showing the configuration of a film forming apparatus according to an embodiment of the present invention. As shown in Fig. 1, the film forming apparatus 1 of the present embodiment is a film forming apparatus using a cold spray method, and includes a gas heater 2 for heating a high-pressure gas (compressed gas), and a powder containing a film forming material, and is supplied to the spray coating. The powder supply device 3 of the gun 4, the spray gun 4 that mixes the heated high-pressure gas and powder and is introduced into the nozzle 5, the nozzle 5 that sprays the powder together with the high-pressure gas, and the gas heater 2 and the powder supply device 3 are separately adjusted. Valves 6 and 7 for the supply of high pressure gas.

The high pressure gas system uses helium, nitrogen, air, and the like. The high-pressure gas system supplied to the gas heater 2 is introduced to the coating gun 4 after being heated to a temperature lower than the melting point of the material powder. The heating temperature of the high pressure gas is preferably from 300 to 900 °C.

On the other hand, the high-pressure gas system supplied to the powder supply device 3 is supplied to the coating gun 4 so that the powder in the powder supply device 3 becomes a predetermined discharge amount.

The heated high-pressure gas system passes through the nozzle 5 to become a supersonic flow (about 340 m/s or more) and is ejected. The gas pressure of the high pressure gas at this time is preferably about 1 to 5 MPa. This is because the pressure of the high pressure gas is adjusted to such an extent that the adhesion strength of the film 101 to the substrate 100 is improved. More preferably, it is a pressure of about 2 to 4 MPa.

In the film forming apparatus 1 as described above, the substrate 100 is placed on the coating gun 4, and the powder of the film forming material is introduced into the powder supply device 3, and the high pressure gas is supplied to the gas heater 2 and the powder supply device 3. Thereby, the powder supplied to the coating gun 4 is charged into the supersonic flow of the high-pressure gas and accelerated, and is ejected from the nozzle 5. This powder directly collides and accumulates the substrate 100 at a high speed in a solid phase state, thereby forming a film 101.

Fig. 2 is an enlarged cross-sectional view showing the inside of the coating gun 4 shown in Fig. 1. As shown in Fig. 2, the spray gun 4 is provided with a gas powder mixing unit 10 that mixes a high-pressure gas and a powder and supplies it to the nozzle 5, and a gas chamber 11 filled with a high-pressure gas introduced into the gas powder mixing unit 10, and a powder. The powder supply tube 12 supplied to the gas powder mixing unit 10, the powder supply tube support portion 13 provided at the boundary between the gas powder mixing unit 10 and the gas chamber 11, and the tubular rectification around the powder supply tube 12 provided in the gas chamber 11. The portion 14 and the temperature sensor 15 and the pressure sensor 16 are disposed in the gas chamber 11. At least one gas passage opening 13a that connects the gas powder mixing unit 10 and the gas chamber 11 is provided in the powder supply tube support portion 13.

The cross section perpendicular to the longitudinal direction of the nozzle 5 of the gas powder mixing unit 10 (hereinafter referred to as a cross section) is formed into a tubular shape having a rotationally symmetrical shape such as a circular shape, an elliptical shape, a rectangular shape, or a polygonal shape, and is in the present embodiment. It is a circular shape. Further, the end region of the gas powder mixing portion 10 is gradually tapered toward the nozzle 5. In the gas powder mixing section 10, gas and powder are simultaneously supplied from the powder supply pipe 12, and gas is introduced from the gas chamber 11 through the gas passage port 13a, and the two are mixed. The powder mixed with the gas is accelerated to be sent to the nozzle 5 by passing through a region where the tip end of the nozzle 5 is thin.

In the gas chamber 11, the heated high-pressure gas is introduced from the gas heater 2 through the gas supply path 17. The pressure in the gas chamber 11 is usually maintained at about 1 to 5 MPa. The high-pressure gas is introduced into the gas-powder mixing section 10 by the pressure difference in the gas chamber 11 and the gas-powder mixing section 10.

The powder supply pipe 12 passes through the gas chamber 11, and the injection port 12a of the powder protrudes into the gas powder mixing portion 10, and the injection port 12a is disposed toward the nozzle 5 side.

Fig. 3 is an enlarged plan view showing the powder supply tube support portion 13. As shown in Fig. 3, an opening 13b into which the powder supply tube 12 can be fitted is provided in the center of the powder supply tube support portion 13, and at least one outer peripheral side of the opening 13b is provided (eight in the present embodiment). The gas passes through the port 13a. The powder supply tube support portion 13 is embedded in the boundary between the gas powder mixing portion 10 and the gas chamber 11. Then, by fitting the powder supply pipe 12 to the opening 13b of the powder supply pipe support portion 13, the powder supply pipe 12 is along The gas powder mixing portion 10 and the rotation center axis of the nozzle 5 are supported.

The flow regulating portion 14 is a tubular member having an opening at both ends, and is disposed around the powder supply pipe 12 such that one open surface touches the gas passage opening 13a, and the other open surface (open surface 14a) faces each other. The inner wall of the gas chamber 11. The high-pressure gas system introduced into the gas chamber 11 from the gas heater 2 flows into the rectifying unit 14 from the opening surface 14a and is rectified, and is introduced into the gas powder mixing unit 10 through the gas passage opening 13a.

Fig. 4 is an X-ray view of the rectifying portion 14 shown in Fig. 2. The opening surface 14a of the flow regulating portion 14 is formed into a circular symmetrical shape such as a circular shape, an elliptical shape, a rectangular shape, or a polygonal shape, in accordance with the cross-sectional shape of the gas-powder mixing portion 10. That is, the opening surface 14a of the rectifying portion 14 is formed into a shape similar to or the same as the cross-sectional shape of the gas-powder mixing portion 10. As shown in FIG. 1 and FIG. 4, in the first embodiment, the opening surface 14a is formed in a circular shape having the same diameter as the gas powder mixing portion 10.

Such a rectifying portion 14 may be formed integrally with the powder supply tube support portion 13. Further, in the present embodiment, the rectifying portion 14 has a columnar shape in which the diameter is uniform in the longitudinal direction, but may be a conical shape.

Next, the rectification unit 14 will be described in detail. As described above, the high-pressure gas system introduced into the gas chamber 11 flows into the rectifying unit 14 from the opening surface 14a, and is rectified while passing through the rectifying unit 14. By introducing the rectified high-pressure gas into the gas powder mixing unit 10, the powder supplied from the powder supply tube 12 to the gas powder mixing unit 10 travels along the longitudinal direction of the gas powder mixing unit 10 and is supplied to the nozzle 5. At this point, the powder in progress It becomes difficult to adhere to the inner wall of the gas-powder mixing section 10, and even if the powder adheres, it adheres uniformly to the inner wall, so that the powder does not locally deposit.

On the other hand, if the rectifying portion 14 is not provided, or the size of the rectifying portion 14 is not appropriate, that is, when the high-pressure gas introduced into the gas-powder mixing portion 10 is not sufficiently rectified, the traveling direction of the powder supplied from the powder supply pipe 12 will be There is some offset. Therefore, the powder may be unevenly adhered to the inner wall of the gas powder mixing portion 10, causing local accumulation.

Here, the inventors of the present invention repeatedly perform the experiment of ejecting the powder from the film forming apparatus 1, and actively study that the high-pressure gas introduced into the gas powder mixing section 10 can be sufficiently rectified so as to be attached to the gas powder mixing section 10. The dimensional condition of the rectifying portion 14 to the extent that the powder of the wall is uniformized.

As shown in Fig. 2, when the width of the gas chamber 11 along the longitudinal direction of the rectifying portion 14 is L ₁ and the length of the rectifying portion 14 in the longitudinal direction is L ₂ , the opening surface 14a is opened to the opening. The distance from the surface 14a to the inner wall of the gas chamber 11 is L ₃ (L ₃ = L _{1 -} L ₂ ). Moreover, the inner diameter of the rectifying portion 14 is set to , setting the outer diameter of the powder supply tube 12 to .

Fig. 5 is an enlarged perspective view showing the vicinity of the opening surface 14a of the flow regulating portion 14. When the rectifying unit 14 is provided in the gas chamber 11, the high-pressure gas system has a distance L ₃ from the opening surface 14a to the inner wall of the gas chamber 11 in the high-pressure gas system. The columnar region 20 of height flows in. In the columnar region 20, high-pressure gas flows from the side surface of the columnar region 20, and high-pressure gas flows out from the opening surface 14a. Here, when the area of the opening surface 14a is A and the area of the side surface of the columnar region 20 is B, the areas A and B can be expressed by the following formulas (1) and (2).

When the inventors of the present invention conducted an experiment to change the relationship between the areas A and B, it is considered that when the following formula (3) is satisfied, the high-pressure gas introduced into the gas powder mixing unit 10 can be sufficiently rectified.

1≦(B/A)≦8...(3)

As described above, according to the present embodiment, by adjusting the length of the rectifying unit 14 so as to satisfy the formula (3), it is possible to prevent the powder supplied from the powder supply tube 12 from being biased toward the inner wall and adhering to the gas powder mixing unit 10. And partially piled up. Moreover, the powder itself adhering to the inner wall of the gas powder mixing portion 10 can be reduced. As a result, the frequency of cleaning the gas powder mixing portion 10 can be reduced, and film formation can be efficiently performed over a long period of time.

(Modification 1)

Next, a first modification of the embodiment will be described. In the above-described embodiment, the gas passage opening 13a is provided by the powder supply pipe support portion 13 (see FIG. 3). However, the number and shape of the gas passage openings 13a are not limited thereto. For example, the powder supply tube support portion 30 shown in Fig. 6 can be applied instead of the powder supply tube support portion 13.

As shown in Fig. 6, the powder supply tube support portion 30 is provided with a peripheral ring 31 that can be fitted to the boundary between the gas powder mixing portion 10 and the gas chamber 11, and abuts against the outer peripheral side of the powder supply tube 12 and powder A plurality of (four in FIG. 6) support bars 32 are supported by the end supply pipe 12. At this time, the area of the gas passage opening 30a can be increased as compared with the gas passage opening 13a shown in Fig. 3. In addition, the number of the support bars 32 is not particularly limited as long as it can support the powder supply tube 12, and it is only necessary to have at least one. At this time, the gas can be integrated through the port 30a.

(Modification 2)

Next, a second modification of the embodiment will be described. In the first drawing, the rectifying unit 14 is shown as an independent member. However, as described above, the rectifying unit 14 and the powder supply tube supporting unit 13 may be integrally formed.

Further, the flow regulating portion 14 and the gas powder mixing portion 10 may be integrally formed. In this case, the powder supply tube support portion 13 may be fitted inside the integrally formed gas powder mixing portion 10 and the rectifying portion 14, and the gas powder mixing portion 10, the rectifying portion 14, and the powder supply tube supporting portion 13 may be 3 They are formed in one piece.

Alternatively, the flow regulating portion 14 may be integrally formed with the gas chamber 11. At this time, the powder supply tube support portion 13 may be fitted into the gas chamber 11 and the rectifying portion 14 which are integrally formed, or the gas chamber 11, the rectifying portion 14, and the powder supply tube support portion 13 may be integrally molded.

Further, the flow regulating portion 14 and the powder supply pipe 12 may be integrally formed. In this case, the powder supply tube support portion 13 may be integrally formed, or may be formed separately from the powder supply tube support portion 13, and the support portion that supports the powder supply tube 12 through the rectifying portion 14 may be integrally formed. .

(Modification 3)

Next, a modification 3 of the embodiment will be described. Figure 7 It is a perspective view which shows the modification of a rectification part. The rectifying unit 40 shown in Fig. 7 includes a tubular portion 41 having a tubular shape at both ends, and a plurality of rectifying fins (four in FIG. 7) provided on the inner wall of the tubular portion 41. 42. Each of the fin fins 42 is a plate-shaped rectifying member, and is disposed such that the longitudinal direction thereof is parallel to the height direction of the tubular portion 41 and one end in the longitudinal direction is aligned with the end surface of one side of the tubular portion 41. In the seventh drawing, although the length of each of the fin fins 42 in the longitudinal direction is shorter than the height of the tubular portion 41, the length of each of the fin fins 42 may be extended to the maximum height of the tubular portion 41. The extent of it.

Fig. 8 is a cross-sectional view showing a state in which the rectifying portion 40 shown in Fig. 7 is attached to the coating gun 4 shown in Fig. 2 in place of the rectifying portion 14. By using the rectifying portion 40 in which the rectifying fins 42 are provided inside, the rectifying effect of the high-pressure gas flowing from the gas chamber 11 through the rectifying portion 40 into the gas-powder mixing portion 10 can be further enhanced.

Moreover, in this case, the tubular portion 41 can be integrally molded with the gas powder mixing portion 10, the gas chamber 11, the powder supply tube 12, or the powder supply tube support portion 13 in the same manner as in the second modification.

[Examples]

(Example 1)

The width L ₁ of the gas chamber 11 is 34 mm, and the length L ₂ of the rectifying portion 14 is 31.6 mm (that is, the distance L ₃ = 2.4 mm), and the inner diameter of the rectifying portion 14 14.8 mm, the outer diameter of the powder supply tube 12 It is 8mm. At this time, the ratio B/A of the area B to the area A is about 1.0, which satisfies the formula (3).

The temperature in the gas chamber 11 is set to 800 ° C, and the pressure is applied. The film was maintained at 4 MPa and 4 kg of copper powder was used for film formation. Thereafter, when the gas powder mixing portion 10 is removed and the inner wall is visually observed, the powder adheres almost uniformly.

(Example 2)

The length L2 of the flow regulating portion 14 is set to 27 mm (that is, the distance L3 = 7 mm), and the dimensions of the other portions are the same as in the first embodiment. The ratio B/A of the area B to the area A is about 3.0, which satisfies the formula (3).

After the film formation was carried out under the same conditions as in Example 1, the gas powder mixing portion 10 was removed to visually observe the inner wall. Fig. 9 is a photograph showing the gas powder mixing portion 10 after the experiment of Example 2. The black area 111 shown in Fig. 9 is a region where the powder adheres. As shown in Fig. 9, on the inner wall of the gas powder mixing portion 10, the powder adheres almost uniformly.

(Example 3)

The length L _{2 of the} flow regulating portion 14 is set to 15.2 mm (that is, the distance L ₃ = 18.8 mm), and the dimensions of the other portions are the same as in the first embodiment. The ratio B/A of the area B to the area A is about 8.0, which satisfies the formula (3).

After the film formation was carried out under the same conditions as in Example 1, the gas powder mixing portion 10 was removed, and when the inner wall was visually observed, the powder adhered almost uniformly.

(Comparative Example 1)

Similarly to the conventional film forming apparatus, the rectifying unit 14 is not installed in the gas chamber 11 (that is, the length L _{2 of the} rectifying unit is 0 mm, and the distance L _{3 is} 34 mm), and film formation is performed under the same conditions as in the first embodiment. . At this time, the ratio B/A of the area B of the area A is about 14.4, and the formula (3) is not satisfied. After the film formation, the gas powder mixing portion 10 was taken out, and when the inner wall was visually observed, the powder adhered to the side of the inner wall.

(Comparative Example 2)

The length L _{2 of the} flow regulating portion 14 is set to 13 mm (that is, the distance L ₃ = 21 mm), and the dimensions of the other portions are the same as in the first embodiment. The ratio B/A of the area B to the area A is about 8.9, and the formula (3) is not satisfied.

After the film formation was carried out under the same conditions as in Example 1, the gas powder mixing portion 10 was removed to visually observe the inner wall. Fig. 10 is a photograph showing the gas powder mixing portion 10 after the experiment of Comparative Example 2. The black area 121 shown in Fig. 10 is a region where the powder adheres. As shown in Fig. 10, on the inner wall of the gas powder mixing portion 10, the powder adheres to a part of the side (the left side of Fig. 10). On the other hand, the region 122 on the side opposite to the region 121 is less likely to adhere to the powder.

4‧‧‧ spray gun

5‧‧‧ nozzle

10‧‧‧Gas Powder Mixing Department

11‧‧‧ gas chamber

12‧‧‧Powder supply tube

12a‧‧‧shots

13‧‧‧Powder Supply Pipe Support Department

13a‧‧‧ gas passage

14‧‧‧Rectifier

14a‧‧‧Open face

15‧‧‧Temperature Sensor

16‧‧‧ Pressure Sensor

17‧‧‧ gas supply road

Claims (8)

A film forming apparatus is a film forming apparatus which sprays a powder of a material together with a gas from a nozzle to directly deposit the powder in a solid phase state and deposits on a surface of the substrate, thereby forming a film, which is provided with a gas powder. a mixing unit that mixes the gas with the powder and supplies the same to the nozzle; the gas chamber communicates with the gas powder mixing unit through at least one gas passage port, and introduces the gas into the gas powder mixing unit; In the tube, the powder is supplied to the gas powder mixing unit, and the gas chamber is inserted through the gas chamber so that the injection port of the powder protrudes from the gas powder mixing portion and is disposed toward the tip end of the nozzle; and the rectifying portion is provided in the foregoing The gas introduced into the gas chamber is rectified around the powder supply pipe in the gas chamber and passed through the at least one gas passage port. The film forming apparatus according to claim 1, wherein the rectifying portion has a tubular member having an opening at both ends, and is disposed such that an opening surface of one of the members touches the at least one gas passage opening The opposite side of the opening is opposed to the inner wall of the gas chamber. The film forming apparatus according to claim 2, wherein an area of the opening surface of the other side into which the gas is introduced into the gas chamber is an area A, and the other side is The opening surface faces the inner wall to the opening surface of the other side The distance is set to the height, and when the area of the side surface of the columnar shape in which the area is the bottom surface is the area B, the area B is equal to or larger than the area A. The film forming apparatus according to claim 3, wherein the area B is 8 times or less of the area A. The film forming apparatus according to claim 2, wherein the rectifying portion further includes a plurality of rectifying members provided on an inner wall surface of the tubular member. The film forming apparatus according to claim 1, wherein the opening surface of the rectifying portion is formed in a shape similar to a cross section orthogonal to the longitudinal direction of the gas powder mixing portion. The film forming apparatus according to claim 6, wherein the opening surface of the rectifying portion is formed to have the same shape as a cross section orthogonal to the longitudinal direction of the gas powder mixing portion. The film forming apparatus according to claim 1, wherein the opening surface of the rectifying portion is formed into a circular shape, an elliptical shape, a rectangular shape, or a polygonal shape.