JP5228149B2 - Nozzle for film formation, film formation method, and film formation member - Google Patents

Description

  The present invention relates to a nozzle shape used in a particle deposition film forming method in which a solid powder, molten or semi-molten material powder particles are collided with a substrate surface together with a gas flow accelerated by a nozzle and deposited to form a film. Further, the present invention relates to a method for producing a film and a member on which a film is formed.

The particle deposition film forming method using powder as a film forming material is compared with a gas phase synthesis method such as a CVD (Chemical Vapor Deposition) method or a PVD (Physical Vapor Deposition) method using gas or vapor as a film forming material. Since a film having a high film speed and a thicker film than the vapor phase synthesis method can be formed at a low cost, it is widely used for surface modification of structural members.

As a particle deposition film forming method, a thermal spraying method in which a material such as a powder, a wire, or a rod is melted or semi-molten using a heat source such as plasma or a combustion flame and sprayed onto a substrate surface is widely used. Also, in recent years, in order to suppress phase transformation such as oxidation and thermal degradation caused by melting of the material, the powder material can be deposited in a solid phase by colliding with the surface of the substrate together with a high-speed gas flow. (Patent Document 2) and the aerosol deposition method (Patent Document 1) have been developed.

However, increasing the particle velocity is indispensable for flattening and depositing solid-state powder material at the time of collision with the substrate, so it is necessary to increase the gas pressure to increase the gas velocity for conveying particles. It becomes. However, since an arc-shaped shock wave front (Bow Shock) is formed in the vicinity of the substrate surface where the high-speed gas flow collides with this, the particles having a small particle size are repelled before reaching the substrate. There were problems such as a decrease in deposition efficiency. In high-speed thermal spraying called HVOF (High Velocity Oxygen Fuel Spraying) or HVAF (High Velocity Aero Fuel Spraying), a flammable gas is explosively burned and ejected from the nozzle. There was a problem.

Here, the arc-shaped shock wave front is a high-pressure region formed near the substrate surface when a high-speed gas flow collides with the substrate, and the gas flow colliding with the substrate surface is the surface. This occurs as a result of repelled countercurrent and a flow along the surface of the base material and complex interference with each other. When such a high-pressure region is formed, the relatively small particles have a weak inertial force, so that they cannot pass through the high-pressure region and are repelled or have a large trajectory, resulting in a decrease in deposition yield. .
JP 2003-073855 A JP 2005-095886 A

Conventionally, as a countermeasure for reducing the influence of the arc-shaped shock wave front, for example, in a film forming method in which powder particles collide with a substrate in a solid state, such as a cold spray method or an aerosol deposition method, helium is used as a gas species. It has been considered effective to use. Since helium is an extremely light gas, it is advantageous in that an arc-shaped shock wave front is hardly formed, but on the other hand, it is expensive and not an industrially effective means. On the other hand, in the high-speed spraying method called HVOF or HVAF, a flammable gas is explosively burned to spray the powder on the substrate surface in a molten or semi-molten state. Therefore, effective countermeasures for the arc-shaped shock wave front could not be made. In general, in the particle deposition film forming method, it is difficult to deposit powder particles on a substrate with a high yield, which has been an obstacle to cost reduction.

An object of the present invention is to reduce the influence of an arc-shaped shock wave front regardless of the type of gas used, a novel nozzle applicable to various particle deposition film forming methods, a film manufacturing method using the same, and film formation By providing a member, a solution to the above problem is provided.

A first invention made to solve the above-mentioned problems relates to a film forming nozzle for forming a film by mixing powder particles in a flow of a high-speed gas and injecting the mixture onto a substrate, in the vicinity of the nozzle tip. An opening for discharging a part of the gas flow is provided, and by releasing a part of the gas flow from the opening, the base of the gas flow is not reduced. As a result, it is possible to reduce the flow rate of the gas impinging on the surface of the material and to reduce the pressure of the arc-shaped shock wave front formed on the surface of the base material. The present inventors have found that the powder particles are sufficiently accelerated by the gas flow in the vicinity of the nozzle tip, and thus advance straight as it is due to the inertial force, and only a part of the gas flow is discharged from the opening. It has been completed. Although the present invention has made it possible to significantly reduce the influence of the arc-shaped shock wavefront, there is no such prior art regarding the nozzle shape, which is a novel structure found by the present inventors. In addition, as a whole structure of the film forming nozzle, nozzles having various structures including a structure capable of obtaining a supersonic speed generally called a Laval nozzle can be used. These existing nozzle structures basically have a tapered conical or pyramidal portion that is a fluid introduction part, and the tip part is narrowed to form a throat part. When the fluid passes through the throat part, the fluid suddenly changes. However, the structure beyond the throat has various shapes such as straight, divergent, and straight following the divergent part. In order to accelerate the powder particles uniformly while adjusting the flow of the gas flow from the throat, a length of about several tens to 300 mm is used. Accordingly, since the powder particles are sufficiently accelerated in the vicinity of the nozzle tip, an opening for discharging only a part of the gas flow can be provided. In the first invention, the vicinity of the nozzle end surface is within 100 mm, more preferably within 50 mm from the end surface of the tip, and may be appropriately determined according to the shape and dimensions of the tip from the throat.

The second invention is characterized in that the opening for discharging a part of the gas flow is in the shape of one or a plurality of holes or slits. Here, the number, size, and shape of the holes or slits are not particularly limited, and various structures such as combinations of holes and slits can be used. The slit may be a substantially rectangular opening or may be an opening formed by cutting from the nozzle tip.

Further, the third invention is characterized in that the total area of the openings is 20% or more of the nozzle outlet cross-sectional area. When the total area of the openings is less than 20% of the nozzle outlet cross-sectional area, the amount of gas released is small, and the effect of reducing the influence of the arc-shaped shock wave front is insufficient, so the ratio is set to 20% or more. Although the effect of reducing the influence of the arc-shaped shock wave front was recognized even when the total area of the opening was increased to about 10 times (1000%) of the cross-sectional area of the nozzle outlet, the angle for forming the opening ( Since the effect varies depending on the angle with respect to the nozzle center axis), the size of the end face radius, and the like, adjustment may be made as appropriate so that the amount of released gas is not excessive.

In the fourth aspect of the invention, the film-forming nozzle according to any one of the first to third aspects is used to eject powder particles of the film-forming material from the nozzle together with the gas flow to deposit the film-forming material on the surface of the substrate. A film manufacturing method characterized by forming a film.

In the fifth invention, the method for producing a film according to the fourth invention is a film forming method in which powder particles such as a cold spray method, an aerosol deposition method and a warm spray method are deposited by colliding with a substrate in a solid state. It is a manufacturing method of the membrane | film | coat characterized by being a method. In order to deposit powder particles by colliding with a substrate in a solid state, a gas flow velocity of approximately 200 m / s or more, and more desirably a sound velocity or more is required. Therefore, the influence of the arc-shaped shock wave front is remarkable. The effect of the present invention is great.

In the sixth invention, the film manufacturing method according to the fourth invention is a film forming method in which powder particles are deposited by colliding with a substrate in a molten or semi-molten state, such as HVOF method, HVAF method, plasma spraying method, etc. It is the manufacturing method of the membrane | film | coat characterized by these. Even in the thermal spraying method in which powder particles are deposited by colliding with a substrate in a molten or semi-molten state, it is necessary to increase the gas flow rate as much as possible in order to reduce the porosity and form a dense film. Therefore, the effect of the present invention can be obtained.

The seventh invention is a method for producing a film, wherein the average particle diameter of the powder particles in the fourth to sixth inventions is 1 to 50 μm. The present invention is effective because it is directly affected by the arc-shaped shock wave front as the particle size becomes smaller, but it is difficult to handle as a powder due to problems such as aggregation and oxidation when the average particle size is less than 1 μm, When it exceeds 50 μm, it is possible to reach the substrate by breaking through the arc-shaped shock wave front by the inertial force of the particles, so the average particle size is set in the range of 1 to 50 μm.

The eighth invention is a method for producing a film, characterized in that the film forming material in the fifth or seventh invention is selected from copper, aluminum, silver, gold, and nickel.

The ninth invention is a member in which a film is formed by using the fourth to eighth inventions.

The gas species used in the present invention is not particularly limited, and for example, compressed air, nitrogen, oxygen, argon, helium, or the like can be used. In the present invention, the powder is fed into the nozzle using a powder feeder and a carrier gas. At this time, the powder feed rate is preferably uniform. In the present invention, various film forming materials and base materials can be selected, and the film can be used for film formation of various metals, ceramics, cermets such as cemented carbide, glass, and organic compounds.

The film-forming nozzle of the present invention can obtain a remarkable particle deposition efficiency improvement effect by a novel structure in which an opening for discharging a part of the gas flow is provided in the nozzle. Further, by reducing the influence of the arc-shaped shock wave front, not only the particle deposition efficiency is improved, but also finer powder particles can be deposited. In connection with these, the base-material adhesion | attachment strength improvement effect of the membrane | film | coat member produced is also acquired.
Since the film manufacturing method of the present invention is made possible by using the film-forming nozzle having this novel structure, it is not necessary to change the current manufacturing process and can be easily carried out.

Examples of the present invention will be described below. However, the present invention is not limited to the examples.

Example 1: Adhesion of pure copper particles (average particle diameter 5.8 μm) to an SS400 substrate using a film forming nozzle having an opening for gas release shown in FIG. 2 using the cold spray device shown in FIG. Efficiency and film adhesion strength (Test method is JIS
H 8661). As the film forming conditions, the gas type was compressed air, the gas pressure at the nozzle inlet was 3.0 MPa, the gas temperature at the nozzle inlet was 300 ° C., the nozzle outlet inner diameter was 7 mm, and the powder supply amount was 16.7 g / min.

As a result of measuring the particle deposition efficiency in the cold spray using the film forming nozzle of FIG. 2, the mass of the copper particles attached to the substrate with respect to the total supply mass of the copper powder was 60%. Moreover, as a result of measuring the adhesive strength of the film, it was 20 MPa. Furthermore, as a result of measuring the particle deposition efficiency in the cold spray using the film-forming nozzle of FIG. 3, the mass of the copper particles attached to the substrate with respect to the total supply mass of the copper powder was 56%. Moreover, it was 19 MPa as a result of measuring the adhesive strength of a film | membrane.

Comparative Example 1: The particle deposition efficiency and the adhesion strength of the coating were measured under the same conditions as in the above example except that the nozzle for forming a gas in the film forming nozzle shown in FIG. 2 was not used.

As a result of measuring the particle deposition efficiency in a cold spray using a nozzle not provided with an opening for releasing gas, the mass of the copper particles attached to the substrate with respect to the total supply mass of the copper powder was 5%. Moreover, as a result of measuring the adhesion strength of the film, it was 16 MPa.

It is a figure which shows the outline | summary of the cold spray apparatus which is an example of the film-forming apparatus using the nozzle in this invention. It is sectional drawing which shows an example of the film-forming nozzle which concerns on this invention which provided the hole for gas discharge | release in the parallel part. It is sectional drawing which shows an example of the film-forming nozzle which concerns on this invention which provided the slit for gas discharge | release in the parallel part.

Explanation of symbols

101: High pressure gas generation unit 102: Gas heater 103: Gas temperature sensor 104: Gas pressure sensor 105: Nozzle 106: Film formation distance 107: Film 108: Base material 109: Base material holding part 110: Powder feeder 111: Carrier gas 112: Gas discharge opening (round hole shape)
113: Gas discharge opening (slit shape)

Claims (9)

  A film-forming nozzle provided with a nozzle outlet for spraying to form a film by mixing powder particles in a high-speed gas flow and spraying onto the substrate, and the gas flow near the nozzle outlet at the nozzle tip A nozzle for film formation, characterized in that an opening for discharging a part thereof is provided.   The film-forming nozzle according to claim 1, wherein the opening for discharging a part of the gas flow has a hole or slit shape at one or a plurality of positions. Film forming nozzle according to any one of claims 1 to 2 total area of the opening, characterized in that at least 20% of the nozzle exit cross-sectional area. Using the film-forming nozzle according to any one of claims 1 to 3, the powder particles of the film-forming material are ejected from the nozzle together with the gas flow, and the film-forming material is deposited on the substrate surface to form a film. A method for producing a film characterized by the following. The method for producing the film is a film forming method comprising a combination of one or more of a cold spray method, an aerosol deposition method, and a warm spray method, and depositing powder particles by colliding with a substrate in a solid state. The method for producing a film according to claim 4, wherein The method for producing the coating film is a film forming method comprising a combination of one or more of an HVOF method, an HVAF method, and a plasma spraying method, in which powder particles are deposited by colliding with a substrate in a molten or semi-molten state. The method for producing a film according to claim 4. The average particle diameter of the said powder particle is 1-50 micrometers, The manufacturing method of the membrane | film | coat in any one of Claims 4-6 characterized by the above-mentioned. The film forming method according to claim 5 or 7, wherein the film forming material is selected from copper, aluminum, silver, gold, and nickel. The member which formed the film | membrane using the manufacturing method in any one of Claims 4-8.