JP4999520B2 - Nozzle for cold spray and cold spray device - Google Patents

Description

  The present invention relates to a cold spray nozzle and a cold spray apparatus using the nozzle, in which the adhesion of the raw material powder to the cold spray nozzle during operation and the blockage of the cold spray nozzle due to this are greatly reduced.

  Conventionally, for example, various metal members such as molds and rolls of steel manufacturing processes, automobile wheels, gas turbine components, etc., in order to improve wear resistance and corrosion resistance and to extend the life of metal members, nickel, copper, A technique for forming a film of aluminum, chromium, or an alloy thereof is known.

  As one method for forming this film, metal plating is used. However, metal plating has problems that it cannot be applied to a large area and cracks are likely to occur.

  Another method includes a method of forming a film by thermal spraying. This thermal spraying includes low pressure plasma spraying (LPPS), flame spraying, high-speed flame spraying (HVOF), atmospheric plasma spraying, and the like. However, when a coating is formed by these thermal spraying, it is difficult to form a dense coating because it is oxidized during thermal spraying, and the conductivity and thermal conductivity are low, the adhesion rate is low, and it is uneconomical. There's a problem.

  As a technique for forming a new film as an alternative to these, “cold spray”, which forms a film of a raw material powder in a solid state, has attracted attention. In this cold spray, a working gas having a temperature lower than the melting point of the raw material powder is made into a supersonic flow, and the raw material powder carried by the carrier gas is put into the working gas and ejected from the tip of the nozzle. A film is formed by colliding with a material. That is, a raw material powder such as a metal, an alloy, an intermetallic compound, or ceramic is collided with the surface of the substrate at a supersonic speed in a solid state to form a film.

  Further, the cold spray technique will be described in detail. A gas supply means from a compressed gas cylinder in which nitrogen gas, helium gas, air and the like are stored is branched into a working gas line and a carrier gas line. The high-pressure working gas is heated to a temperature not higher than the melting point of the raw material powder by a heater and then supplied into the chamber of the cold spray gun. On the other hand, the high-pressure carrier gas is introduced into the raw material powder supply means to carry the raw material powder into the chamber. The raw material powder conveyed by the carrier gas becomes a supersonic flow by the working gas through the conical compression part of the nozzle, and is ejected from the nozzle outlet located at the tip of the conical expansion part, and is in a solid state on the substrate surface. Collide with to form a film.

  This cold spray coating is dense, high density, high conductivity, high thermal conductivity, less oxidation and thermal alteration, and better adhesion than the previously proposed thermal spray coating. It is known.

  A major problem with this cold spray is the adhesion of the raw material powder to the nozzle and the clogging of the nozzle due to this. The nozzle is usually manufactured using stainless steel, tool steel, cemented carbide, etc., but when forming a film by cold spraying using nickel, copper, stainless steel or alloys thereof as a raw material, the nozzle The raw material powder adheres to each part, particularly the expanded part, and further the nozzle is closed. This is because, during operation, friction occurs between the raw material powder and the inner surface of the nozzle, the temperature of the inner surface of the nozzle rises, and the raw material powder adheres to the inner surface of the nozzle. This causes a system failure and requires frequent nozzle replacement work. Such adhesion of the raw material powder to the nozzle and nozzle clogging due to this occurred in several minutes after the operation, which has been a major obstacle in the practical application of the cold spray technique.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-298863) discloses a nozzle for cold spray technology in which at least an expanded portion (enlarged portion) of a nozzle is made of polybenzimidazole, and the nozzle is attached to the nozzle by metal powder. It is said that nozzle clogging can be reduced.

Patent Document 2 (Japanese Patent Application Laid-Open No. 2005-95886) includes a conical tapered portion that continues to the nozzle inlet, a short conical widened portion that extends through the throat portion of the tapered portion, and a widened portion. There has been disclosed a cold spray nozzle comprising a continuous cylindrical parallel part and provided with a desorption mechanism and / or a powder inlet in the parallel part (Claim 1). In Patent Document 2, by specifying the nozzle design described above, an inexpensive standard pipe material can be used, and the parallel part can be easily replaced, so that powder is deposited in a large area construction of 0.5 m ² or more. However, it is said that only the cylindrical portion can be easily exchanged, and when nozzle clogging occurs in the throat portion, the divergent portion, etc., maintenance of the nozzle is facilitated.

  As in Patent Document 1, when polybenzimidazole is used as the nozzle material, the adhesion of the raw material powder to the nozzle and the clogging of the nozzle can be reduced to a certain limit. However, since polybenzimidazole is a resin, it is easily worn by the collision of spray particles, so that not only the nozzle life is short, but furthermore, the heat resistance is low, so it cannot be used at a high temperature of 500 ° C. or higher.

  Patent Document 2 is intended to facilitate the replacement of the nozzle member, and is not intended to reduce the adhesion of the raw material powder to the nozzle and the blocking caused by this.

  As described above, the practical problem in the cold spray technique, that is, the adhesion of the raw material powder to the nozzle and the clogging of the nozzle due to this, has not been solved yet.

JP 2004-298863 A Japanese Patent Laid-Open No. 2005-95886

  Accordingly, an object of the present invention is to greatly reduce the adhesion of raw material powder to the cold spray nozzle during operation and the blockage of the cold spray nozzle caused by this adhesion, and a cold spray nozzle capable of achieving a long service life. An object of the present invention is to provide a cold spray device using the cold spray nozzle.

  Therefore, as a result of intensive studies, the inventors have arrived at the following invention as a means for achieving the above-mentioned problems.

That is, the nozzle for cold spray according to the present invention includes a tapered conical compression part and a conical and widening conical expansion part communicating with the compression part, and the raw material powder is formed using a working gas having a melting point or lower. allowed to flow from the nozzle inlet of the compression unit, a nozzle for cold spray for jetting a supersonic flow from the nozzle outlet of the inflation tip, the inflatable portion is formed of ceramics material at least the inner circumferential wall is made of a silicon nitride ceramic It is characterized by being.

The nozzle for cold spray according to the present invention, a ceramic material made of silicon nitride ceramics, it is preferable to mold the entire inflatable portion and the compression unit.

  In the cold spray nozzle according to the present invention, it is preferable that the expansion portion and the compression portion of the cold spray nozzle are integrally formed.

  The cold spray device according to the present invention comprises a raw material powder supply means for supplying raw material powder, a gas supply means for supplying working gas and carrier gas, and the raw material powder with the working gas having a melting point or lower. A cold spray device including a cold spray gun provided with a nozzle that is jetted as a supersonic flow using any of the above-described cold spray nozzles.

  The cold spray nozzle according to the present invention and the cold spray device using the cold spray nozzle are capable of preventing the raw powder from adhering to the inner wall of the cold spray nozzle during operation and blocking the cold spray nozzle due to this. Since it can be greatly reduced and the life of the cold spray nozzle can be extended, frequent replacement of the cold spray nozzle becomes unnecessary. And since the inner peripheral wall surface of the nozzle for cold spray which concerns on this invention is based on a ceramic material, it can be pickled. Therefore, even if the raw material powder adheres to the inner peripheral wall surface of the cold spray nozzle, there is an advantage that the attached raw material can be easily removed by dipping in an acid solution.

  Hereinafter, the best mode for carrying out the present invention will be described in detail. Here, FIG. 1 is a schematic sectional view showing an embodiment of a cold spray nozzle according to the present invention.

  In FIG. 1, a cold spray nozzle 1 includes a tapered conical compression portion 1b having a nozzle inlet 1a at an end thereof and a conical expansion portion having a nozzle opening 1d at an end thereof and a tapered conical expansion portion. 1c. The cold spray nozzle according to the present invention only needs to have at least the compression portion 1b and the expansion portion 1c described above, and other shapes are arbitrary. For example, a narrow throat portion may be provided between the compression portion 1b and the expansion portion 1c, or a cylindrical parallel portion may be provided on the nozzle outlet side of the expansion portion 1c. In addition, in FIG. 1, an arrow line shows the flow of raw material powder.

The present invention, at least of at least the expansion unit 1c, the inner wall portion, a ceramic material made of silicon nitride ceramics (hereinafter, simply referred to as silicon nitride ceramics) are formed form by the. Here, are speaking of at least the inner circumferential wall, the metal on the outer periphery of the expansion portion, by using a material such as a heat-resistant resin, only the inner circumferential wall, the one that a state of being lined with silicon nitride ceramics The meaning is included. If the outer peripheral portion is made of metal, heat-resistant resin or the like in this way, the ceramic layer on the inner wall portion is accidentally bumped, and damage such as chipping is unlikely to occur, and the handleability is excellent.

The inner peripheral wall surface of the inflated portion 1c, easily adheres most raw material powder, so prone clogging of the nozzle for cold spray is most attributable to this, this part of silicon nitride ceramics, by molding, the raw material powder It is possible to greatly reduce the adhesion of the nozzle and the clogging of the cold spray nozzle due to this.

Further, in the present invention, as described above, the inner peripheral wall surface of at least the expansion unit 1c has to be thus formed into silicon nitride ceramics, other parts such as the compressor unit 1b is conventionally used You may shape | mold with the stainless steel etc. which are the nozzle material for cold spray. However, preferably, the whole was, including other parts, it is desirable that at least the inner peripheral wall surface is thus formed into silicon nitride ceramics. The entire inner peripheral wall surface of the silicon nitride ceramics are present, even in not only the expansion unit 1c only the compressed portion 1b and the like, can be greatly reduced clogging of the nozzle for cold spray to adhere and due to the raw material powder it can.

Accordingly, the whole of the expansion portion is preferably formed of a silicon nitride ceramics. This is because it is a single material and easy to process. Further, the entire of the cold spray nozzle 1 is more silicon nitride ceramics, it is manufactured as an integral molded body is desirable from the viewpoint of economy.

How the expansion unit 1c, etc., are manufactured in a single material of silicon nitride ceramics is not particularly limited, die press molding, isostatic molding, injection molding, slip casting, molding such as extrusion molding, reaction It is preferable to directly form the shape of the expanded portion by selectively using any one of sintering methods such as sintering, normal pressure sintering, pressure sintering, and re-sintering. This is because, in the case of a ceramic material, physical processing after sintering is difficult.

Here, silicon nitride ceramics refers to ceramics mainly composed of silicon nitride (Si ₃ N ₄ ), and here includes sialon which is a solid solution of silicon nitride. This silicon nitride ceramics is a highly reliable structural engineering ceramic having an excellent balance of mechanical properties such as heat resistance and toughness, and is a crystal that is firmly stabilized by covalent bonding. Therefore, as described above, it has excellent heat resistance, high hardness, and good wear resistance. The crystal structure is such that the α type in the low temperature phase is trigonal and the β type in the high temperature phase is hexagonal. Ordinary silicon nitride undergoes a phase transition at 1400-1600 ° C. Silicon nitride powder is chemically stable and does not sinter even when heated simply to high temperatures. In practice, a minute amount of magnesium oxide, aluminum oxide, yttrium oxide, or the like, which is a sintering aid, is added to create a grain boundary phase to obtain a dense sintered body. Silicon nitride ceramics decompose at 1800 ° C. or higher, but have a low thermal expansion coefficient of about 3 to 3.5 × 10 −6 K−1 and a relatively high thermal conductivity, so that they have excellent heat dissipation characteristics and also have anti-sputtering characteristics. Excellent and suitable for cold spray nozzles.

  FIG. 2 is a schematic view of a cold spray apparatus according to the present invention. In FIG. 2, the gas supply means is formed of a compressed gas cylinder 2, a working gas line 3 and a carrier gas line 4. The working gas line 3 and the carrier gas line 4 are provided with pressure regulators 5a and 5b, flow rate regulating valves 6a and 6b, flow meters 7a and 7b, and pressure gauges 8a and 8b, respectively, and working gas from the compressed gas cylinder 2 and The pressure and flow rate of the carrier gas are adjusted.

  The working gas line 3 is provided with a heater 10 heated by an electric power source 9, and the working gas is heated to a temperature below the melting point of the raw material powder and then introduced into the chamber 12 in the cold spray gun 11. . A pressure gauge 13 and a thermometer 14 are installed in the chamber 12 to control pressure and temperature.

  On the other hand, the raw material powder supply means includes a raw material powder supply device 15, a meter 16 attached thereto, and a raw material powder supply line 17.

  The carrier gas from the compressed gas cylinder 2 passes through the carrier gas line 4, is introduced into the raw material powder supply device 15, and a predetermined amount of raw material powder measured by the measuring device 16 passes through the raw material powder supply line 17 into the chamber 12. Transport.

  Examples of the raw material powder used here include metals, alloys, and intermetallic compounds, and specific examples thereof include nickel, iron, silver, chromium, and powders of these alloys.

  The raw material powder transported into the chamber 12 by the transport gas is ejected from the tip of the cold spray nozzle 1 as a supersonic flow using the working gas, and is collided with the base material 18 in a solid state or a solid-liquid coexistence state. Form a film.

As described above, the cold spray nozzle 1 used here includes a tapered and conical compression portion 1b and a conical and expanding conical expansion portion 1c communicating with the compression portion 1b, and at least the expansion portion 1c. the inner peripheral wall surface of, are thus formed on the silicon nitride ceramics.

  For this reason, as described above, adhesion of the raw material powder to the cold spray nozzle during cold spray operation and blockage of the cold spray nozzle due to this can be greatly reduced.

  Hereinafter, the present invention will be specifically described based on examples and the like.

[Example 1]
The nozzle cold spray shown in FIG. 1, as an integral molded article was produced using the silicon nitride ceramics. Using this cold spray nozzle, a cold spray operation was performed with the cold spray apparatus shown in FIG. The cold spray operating conditions and the equipment used are as shown in Table 1 below.

[Reference Example 1]
The nozzle shown in FIG. 1 was integrally formed using zirconia ceramic. Cold spraying was performed by the cold spray apparatus shown in FIG. 2 using this nozzle. The operating conditions and the equipment used are the same as in Example 1.

[Reference Example 2]
The nozzle shown in FIG. 1 was integrally formed using silicon carbide ceramic. Cold spraying was performed by the cold spray apparatus shown in FIG. 2 using this nozzle. The operating conditions and the equipment used are the same as in Example 1.

[Comparative Example 1]
The nozzle shown in FIG. 1 was integrally formed using conventionally used stainless steel. Cold spraying was performed by the cold spray apparatus shown in FIG. 2 using this nozzle. The operating conditions and the equipment used are the same as in Example 1.

Table 2 shows the results of cold spraying of Example 1, Reference Examples 1 and 2 and Comparative Example 1, respectively.

Example, Comparison Reference Example and Comparative Example: As seen from Table 2, Example 1 also Reference Examples 1 and 2 and Comparative Example 1 there is no difference in terms of nozzle wear. Since the working gas temperature is as high as 500 ° C. to 600 ° C., the raw material powder approaches a solid-liquid mixed state (semi-solid), and the impact of the raw material particles colliding with the inner wall portion of the cold spray nozzle is reduced. Therefore, it is considered that the difference in the constituent materials of the cold spray nozzle does not appear clearly.

However, when the situation of nozzle blockage is seen, compared with Comparative Example 1 , Example 1 and Reference Examples 1-2 are clearly superior . The higher the working gas temperature is and the closer the raw material powder is to the solid-liquid mixed state, the more noticeable the adhering raw material particles adhere to the inner wall portion of the cold spray nozzle. In the case of the cold spray nozzle formed using the stainless steel of Comparative Example 1 , the adhesion phenomenon appears remarkably, and the plug is blocked in 3 to 4 minutes, so that the cold spray operation becomes impossible. On the other hand, in the case of a nozzle for cold spray formed by any one of silicon nitride ceramics, zirconia ceramics, and silicon carbide ceramics shown as Example 1 and Reference Examples 1 and 2 , raw material particles for the inner wall surface In the cold spray operation for 30 minutes, no nozzle clogging occurs.

However, in the case of the cold spray nozzle formed by zirconia ceramics and silicon carbide ceramics shown as Reference Examples 1 and 2, compared with the cold spray nozzle formed by silicon nitride ceramics shown as Example 1, the thermal spray efficiency It was inferior to.

  With the cold spray nozzle and the cold spray device using the nozzle according to the present invention, the adhesion of the raw material powder to the nozzle during cold spray operation and the resulting nozzle blockage can be greatly reduced, and the life of the nozzle is extended. Can be achieved. For this reason, frequent replacement of the nozzles becomes unnecessary. Therefore, the present invention is extremely useful for practical application of cold spray technology.

  Moreover, since the inner peripheral wall surface of the nozzle for cold spray according to the present invention is based on a ceramic material, it can be pickled. Therefore, even if the raw material powder adheres to the inner peripheral wall surface of the cold spray nozzle, the adhering raw material on the inner peripheral wall can be easily removed by immersing it in an acid solution, etc. The nature will also increase.

It is a schematic sectional drawing which shows one Embodiment of the nozzle for cold spray which concerns on this invention. It is the schematic of the cold spray apparatus which concerns on this invention.

DESCRIPTION OF SYMBOLS 1 Cold spray nozzle 1a Nozzle inlet 1b Compression part 1c Expansion part 1d Nozzle outlet 2 Compressed gas cylinder 3 Working gas line 4 Carrier gas line 5a, 5b Pressure regulator 6a, 6b Flow control valve 7a, 7b Flowmeter 8a, 8b Pressure gauge 9 Power source 10 Heater 11 Cold spray gun 12 Chamber 13 Pressure gauge 14 Thermometer 15 Raw material powder supply device 16 Meter 17 Raw material powder supply line 18 Substrate arrow line Flow of raw material powder

Claims (4)

A tapered conical compression section and a conical and expanded expansion section communicating with the compression section, and the raw material powder is introduced from the nozzle inlet of the compression section using a working gas having a melting point or less, and the expansion section A cold spray nozzle that ejects as a supersonic flow from the nozzle outlet at the tip,
The expansion unit has a nozzle for cold spray, characterized in that at least the inner peripheral wall surface is formed of a ceramic material made of silicon nitride ceramics. A ceramic material made of silicon nitride ceramics, a nozzle for cold spray according to claim 1 obtained by forming the whole of the expansion section and the compression section. The cold spray nozzle according to claim 2, wherein an expansion portion and a compression portion of the cold spray nozzle are integrally formed. Cold spray provided with raw material powder supply means for supplying raw material powder, gas supply means for supplying working gas and carrier gas, and a nozzle for ejecting the raw material powder as supersonic flow using the working gas below the melting point A cold spray device including a gun,
A cold spray apparatus according to any one of claims 1 to 3, wherein the nozzle is a cold spray nozzle.

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