JP2007253099A - Method for forming film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a film that enables an AD film which is a fine ceramic layer to be formed on the circumferential curved surface of a base material such as a bearing outer periphery. <P>SOLUTION: In the method for forming a film where the ceramic film is formed on the circumferential curved surface of a base metal by an aerosol deposition method, the base material 4 and an aerosol spray nozzle 9 are housed in a vacuum chamber 2. An aerosol having fine particles of the raw material ceramics dispersed in a gas is jetted from the aerosol spray nozzle 9 to the circumferential curved surface of the base material 4 that rotates circumferentially or moves axially to form the ceramic film. A positioning XY table 5 moves the base material 4 in the axial direction, whereas a motor 6 for rotating an object installed on the XY positioning table 5 rotates the base material 4 circumferentially. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a film forming method for forming a film on a circumferential curved surface of a substrate such as a bearing outer periphery by an aerosol deposition method (hereinafter referred to as AD method).

  For the purpose of forming a dense protective film on the surface of a substrate to express the physical and chemical properties such as the mechanical strength inherent to the substrate and to compensate for the physical and chemical properties that are inferior in corrosion resistance, etc. As an effective means, conventionally, a method of forming a sprayed coating such as ceramics on the surface of a substrate is known. However, the method of providing a ceramic layer on the substrate surface using thermal spraying technology is to form a ceramic layer while cooling the workpiece to prevent tempering due to heat during thermal spraying of the base material cured by heat treatment. It had to be done, was very complicated, and caused a decrease in productivity. Furthermore, if a ceramic layer is to be provided on the surface of the substrate by a thermal spraying method, it is necessary to spray a layer of nickel aluminum or the like in advance as a base treatment, which also causes a decrease in productivity.

  In addition, since the ceramic layer obtained by the thermal spraying method is porous, it is necessary to take measures against a decrease in physical properties such as insulation resistance due to intrusion of moisture due to condensation or the like by sealing treatment. For the sealing treatment, a method using a sealing resin containing at least one selected from the group consisting of a synthetic resin, a polymerizable organic solvent, and a fluorosurfactant and a perfluoro group-containing organosilicon compound (Patent Document 1). And a method of sealing by forming a combination layer having a sealing treatment layer made of a resin having good permeability as a lower layer and a sealing treatment layer made of an insulating resin having poor permeability as an upper layer (see Patent Document 2) ) Etc. are known. However, when these sealing methods are used, there is a problem that the cost becomes very high.

  In contrast, an aerosol in which raw material ceramic fine particles are dispersed in a gas is sprayed from an aerosol injection nozzle toward a base material, and the aerosol collides with the surface of the base material at a high speed, thereby forming a coating film made of a constituent material of ultrafine particles. An AD method for forming on a material is known. As an example of the AD method, an ultrafine particle molded body, which is a brittle material containing a fine crystal having a crystal size of 100 nm or less at 95% or more of the theoretical density by bonding an ultrafine particle brittle material of 50 nm to 5 μm on a substrate There is a low-temperature molding method of the obtained brittle material ultrafine particle compact (see Patent Document 3). With the AD method, a dense film of several μm to several tens of μm can be formed with good adhesion, and it is manufactured compared to the thermal spraying method because it does not require cooling of the workpiece, does not require base treatment such as nickel aluminum, and does not require sealing. There is an advantage that the cost is significantly reduced.

However, conventional film formation by the AD method is intended for flat plate substrates used for electronic materials and the like, and there is no film formed on a circular curved surface such as a cylindrical shape. Since the film obtained by the AD method has many excellent properties as described above, application to various industrial machine parts (not limited to flat surfaces) is desired as an insulating film or a corrosion-resistant film.
Japanese Patent Laid-Open No. 2003-183806 Japanese Patent No. 3009516 Japanese Patent No. 3265481

  The present invention has been made to cope with such problems, and provides a film forming method capable of forming an AD film, which is a dense ceramic layer, on a circumferential curved surface of a substrate such as a bearing outer periphery. Objective.

  The film forming method of the present invention is a film forming method for forming a ceramic film on a circumferential curved surface of a substrate by an aerosol deposition method, wherein the substrate and an aerosol injection nozzle are arranged in a vacuum chamber, and the circumferential direction A ceramic coating is formed by spraying and colliding aerosol, in which fine particles of raw material ceramics are dispersed in a gas, from the aerosol spray nozzle on the circumferential curved surface of the base material that rotates or moves in the axial direction. To do.

  The axial movement is performed using a positioning XY table, and the circumferential rotation is performed using an object rotating motor installed on the positioning XY table.

In the film forming method of the present invention, the base material and the aerosol injection nozzle are arranged in a vacuum chamber and rotated in the circumferential direction, or on the circumferential curved surface of the base material moving in the axial direction, Since the ceramic coating is formed by spraying and colliding with the aerosol from the aerosol spray nozzle, the aerosol coating is applied repeatedly on the circumferential curved surface of the substrate, and the dense coating does not connect the coating surface and the substrate substrate. Can be formed.
In addition, since the film is formed at room temperature, even when α-alumina is used, α-alumina is not transformed into γ-alumina, and an α-alumina film having high insulation and the like can be obtained. Furthermore, the manufacturing cost is significantly reduced compared to the thermal spraying method because the workpiece does not need to be cooled, the base treatment such as nickel aluminum is unnecessary, and the sealing treatment is unnecessary.

In the present invention, the AD method is composed of a constituent material of fine particles, in which an aerosol in which fine particles of raw material ceramics are dispersed in a gas is sprayed from an aerosol jet nozzle toward a base material, and the aerosol collides with the base material surface at high speed. This is a method of forming a film on a substrate. The ceramic fine particles are pulverized by collision to form a clean new surface and cause low-temperature bonding, so that bonding between the fine particles can be realized at room temperature.
In the aerosol, the ceramic fine particles are maintained in a dispersed state. The coating obtained by the thermal spraying method is porous, whereas the coating obtained by the AD method forms the coating from the fine particles dispersed in the aerosol as described above, so that the resulting coating becomes an extremely dense ceramic layer. .
Since the ceramic coating by the AD method is dense and excellent in insulation, corrosion resistance, etc., the film thickness required to ensure certain characteristics can be made thinner than that of the thermal spray coating.

In the present invention, any fine particles that can be used in the AD method can be used as the ceramic fine particles used as the aerosol raw material for forming the ceramic film by the AD method. In the case of forming a film excellent in insulation and corrosion resistance, for example, oxide ceramic fine particles such as alumina, zirconia, and titania can be used. In the high-purity grade of each ceramic, alumina particles are preferred because the one with a lower true specific gravity is more easily aerosolized.
The average particle diameter of the alumina fine particles that can be used in the present invention is 0.01 μm to 2 μm. If it is less than 0.01 μm, it is easy to agglomerate and it is difficult to form an aerosol. In the present invention, the average particle diameter is a value measured by Nikkiso Co., Ltd .: Laser type particle size analyzer Microtrac MT3000.

  The particle size adjustment method of alumina fine particles includes alkoxide method and colloid method, pyrolysis method of ammonium alum, ammonium aluminum carbonate pyrolysis method, improved buyer method, chemical method of ethylene chlorohydrin method, gas evaporation method Or fine particles of several tens of nanometers or less, produced by physical methods such as sputtering (vapor phase oxidation) or aluminum underwater spark discharge, to form secondary particles of several hundred nanometers in diameter. The method of aggregating is mentioned. In addition, in order to satisfactorily form a film, it is preferable to previously form a crack using a pulverizer such as a ball mill or a jet mill so that the alumina fine particles are easily pulverized at the time of collision with the substrate.

  Unlike the thermal spraying method, the AD method does not require a high-temperature treatment, and therefore does not cause deterioration in physical properties due to transformation of the raw material ceramic due to exposure to a high temperature. For example, even if α-alumina with excellent insulating properties is used, the thermal spraying method transforms to γ-alumina and lowers the insulating properties. Therefore, it is necessary to increase the film thickness. Since the film can be formed with high α-alumina, a ceramic layer with high insulation can be obtained.

  The film forming method of the present invention is a method of forming an AD film on a circumferential curved surface, in which a substrate and an aerosol injection nozzle are arranged in a vacuum chamber, and the substrate is rotated in the circumferential direction or moved in the axial direction. A ceramic coating is formed on the circumferential curved surface by spraying and colliding with an aerosol from an aerosol spray nozzle. Since the base material to be coated is rotated and moved, and the aerosol injection nozzle is fixedly arranged, the aerosol can be sprayed in a stable state.

A method of forming a film on a circumferential curved surface using the AD method will be described with reference to FIG. FIG. 1 is a view showing a film forming apparatus when an insulating ceramic film is formed on the outer peripheral surface of a bearing outer ring by the film forming method of the present invention.
As shown in FIG. 1, a ceramic film forming apparatus 1 using an AD method has a vacuum chamber 2. In the vacuum chamber 2, an outer ring 4 that is an object for forming a ceramic film and an aerosol injection nozzle 9 are disposed. Aerosol is supplied from the aerosol generator 8 to the aerosol injection nozzle 9. The inside of the vacuum chamber 2 is depressurized by the vacuum pump 3. In order to prevent mixing of ceramic fine particles, a fine particle filter 10 is provided immediately before the vacuum pump 3. The outer ring 4 is rotated in the vacuum chamber 2 by an object rotating motor 6 (A in the figure) and moved in the axial direction by a positioning XY table 5 (B in the figure). In FIG. 1, the outer ring 4 is pivotally supported by an object rotation motor 6, and the object rotation motor 6 is supported by a positioning XY table 5.
As an aerosol carrier gas, an inert gas is used and supplied from the gas supply facility 7 to the aerosol generator 8. Usable inert gases include argon, nitrogen, helium and the like.

The aerosol injection nozzle 9 injects ceramic fine particles from the nozzle tip having an opening such as a rectangle toward the outer peripheral surface of the outer ring, which is a circumferential curved surface. In addition, the aerosol injection nozzle 9 may be one or plural. The aerosol injection nozzle 9 may be configured to be displaceable in the vacuum chamber 2.
Further, the aerosol injection nozzles 9 are arranged so that they can be simultaneously injected over the entire range of the axial length of the circumferential curved surface, for example, by arranging a plurality of linear nozzles along the axial direction of the base material, Only the rotation of the motor 6 makes it possible to coat the entire surface of the circumferential surface, and the positioning XY table 5 becomes unnecessary.
The aerosol incident angle is preferably within a range of ± 80 ° with respect to a direction (normal line) based on an axis passing through the center and perpendicular to the circumferential tangent. Outside this range, etching proceeds and film formation cannot be performed. The rotation direction may be forward rotation or reverse rotation regardless of the aerosol injection angle.

Aerosol made of ceramic fine particles is injected from the fixed aerosol injection nozzle 9 to the outer ring 4 rotated at a predetermined number of revolutions by the object rotating motor 6, and the nozzle on the outer peripheral surface of the outer ring 4 that is a circumferential curved surface. A ceramic film is formed on the passing position. In the case of a base material other than the one that can be pivotally supported, such as an outer ring, for example, a method of sandwiching and rotating the base material from both sides at the center axis position of the circumferential curved surface can be adopted.
Further, by moving the outer ring 4 in the axial direction by the positioning XY table 5, the nozzle passing position on the circumferential curved surface moves, and a coating can be formed over the entire circumferential curved surface.

The aerosol injection speed is preferably 100 to 1000 m / s. Otherwise, a dense film cannot be formed.
The film formation is performed until the film thickness reaches a predetermined film thickness depending on the use of the substrate. As a procedure for forming the coating, a method of forming the coating by rotating it to the predetermined film thickness at an arbitrary location on the base material and sequentially moving it in the axial direction, or simultaneously performing the rotation and the axial movement, For example, a method of reciprocating in the axial direction until the film thickness is obtained.

Example Using the apparatus shown in FIG. 1, a coating made of alumina fine particles was formed on the outer peripheral surface of an outer ring (6202: SUJ2, dimensions 35 mm × 29 mm × 15 mm) which is a circumferential curved surface by the AD method.
The AD method uses a driving device that uses a positioning XY table 5 and an object rotation motor 6 in combination with an outer ring that rotates at a peripheral speed of 110 mm / min and moves in the axial direction at 10 mm / min. A coating was formed by spraying an aerosol of alumina fine particles through a nozzle having an opening size of 5 mm × 0.3 mm under a reduced pressure of 100 Pa or less. The axial movement by the positioning XY table 5 was formed by turning back and forth 10 times at the end of the outer peripheral surface of the outer ring.
Alumina fine particles were manufactured by Daimei Chemical Industry Co., Ltd .: Tymicron TM-DAR, and used after heat-drying under reduced pressure of 10 Pa or less with an average particle size of 0.16 μm. Helium was used as the carrier gas, and the particle velocity was controlled by the carrier gas flow rate.
In the outer ring thus obtained, a ceramic film composed of α-alumina fine particles was uniformly formed on the outer peripheral surface with a thickness of 5 μm.

  Since the coating film forming method of the present invention can form an AD coating, which is a dense ceramic layer, on the circumferential curved surface of the substrate, it can be suitably used for coating coating on various industrial machine parts having a circumferential curved surface.

It is a figure which shows the ceramic film formation apparatus by AD method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic film formation apparatus 2 Vacuum chamber 3 Vacuum pump 4 Outer ring 5 XY table for positioning 6 Motor for object rotation 7 Gas supply equipment 8 Aerosol generator 9 Aerosol injection nozzle 10 Fine particle filter

Claims (2)

A film formation method for forming a ceramic film on a circumferential curved surface of a substrate by an aerosol deposition method,
A base material and an aerosol injection nozzle are arranged in a vacuum chamber, and fine particles of the ceramic material are dispersed in the gas from the aerosol injection nozzle on the circumferential curved surface of the base material that rotates in the circumferential direction or moves in the axial direction. A ceramic film is formed by spraying and colliding a sprayed aerosol.   The axial movement is performed using a positioning XY table, and the circumferential rotation is performed using an object rotation motor installed on the positioning XY table. Item 2. A method for forming a film according to Item 1.

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