JP2007239856A - Corrosion resistant/chemical resistant rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrosion resistant/chemical resistant rolling bearing capable of forming a fine ceramic layer using a method replacing a spraying process and maintaining superior corrosion resistance and chemical resistance. <P>SOLUTION: The corrosion resistant/chemical resistant rolling bearing is equipped with an inner ring 1, and outer ring 2, and a plurality of rolling elements 4 interposed between the raceway surfaces of the inner ring 1 and the outer ring 2, and includes a ceramic film 7 at least on surfaces (1a, 2a) of the inner ring 1 and the outer ring 2 contacting a corrosive substance. The ceramics film 7 is formed by an aerosol deposition method using alumina minute particles as an aerosol material. The film, for example, is formed by fixing an aerosol injection nozzle, and moving the outer ring 2 or the inner ring 1 in the axial direction using a positioning XY table while rotating it using an object rotating motor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant / chemical-resistant rolling bearing, and more particularly to a corrosion-resistant / chemical-resistant rolling bearing that can be used in an environment where metal is easily corroded by contact with various chemicals such as acids and alkalis used in chemical plants. About.

  In chemical plant equipment such as polymer material manufacturing plants and liquid crystal film manufacturing equipment, there are various processing equipment that uses various chemicals such as acids and alkalis. Among them, rolling bearings are used for stirring and conveying. Has a problem that it has a relatively short life because it causes deterioration of quality such as corrosion, swelling, dissolution, decomposition, etc. by contact with various chemicals such as acid and alkali. For the inner ring, outer ring, rolling elements, and cage constituting the bearing, stainless steel, ceramics, resin, and the like having corrosion resistance and chemical resistance are generally used. However, stainless steel is not always universal and applicable chemicals such as acids and alkalis are limited. Ceramics exhibit excellent corrosion resistance and chemical resistance against chemicals such as acids and alkalis, but are expensive.

In recent years, resins have been used in various environments such as corrosive environments and various chemical use environments by selecting types that have mechanical strength and slidability, and by selecting types that are resistant to chemicals such as acids and alkalis. Widely used in the field.
Conventionally, as a synthetic resin rolling bearing, at least an outer ring is a rolling bearing made of a polyimide material (see Patent Document 1), and a polyphenylene sulfide (hereinafter referred to as PPS) resin in which a bearing ring has a bending elastic modulus of 2000 to 6000 MPa. Resin rolling bearings (see Patent Document 2) formed of polyarylene sulfide-based resins such as polytetrafluoroethylene (hereinafter referred to as PTFE) resin on the surface that causes rolling friction or sliding friction of the inner ring and outer ring A rolling bearing (see Patent Document 3) having a lubricating coating is known.
In addition, a film forming member containing a crystalline high molecular weight PTFE resin is pressed against at least a surface that generates rolling friction or sliding friction among the components constituting the rolling bearing, and the PTFE is applied to the surface by sliding between the two. A rolling bearing (see Patent Document 4) that forms a solid lubricating film of resin is known.
However, the rolling bearings whose inner ring or outer ring has a rolling surface made of resin as described above are generally inferior to steel in terms of load resistance, and rolling elements harder than the resin forming the rolling surface roll. Therefore, the wear of the rolling surface is remarkable, and the durability of the rolling bearing is not sufficient.

On the other hand, as a method for imparting corrosion resistance and chemical resistance to steel inner rings and outer rings, conventionally, a method of forming a thermal spray coating having corrosion resistance and chemical resistance such as ceramics on the outer surface of a bearing race is known. Yes.
However, the method of providing a ceramic layer on the outer diameter surface and width surface of the bearing using thermal spraying technology is to prevent the tempering of the bearing steel cured by heat treatment during the thermal spraying process while cooling the workpiece while cooling the ceramic. Layers had to be deposited, which was very cumbersome and reduced productivity. Furthermore, if an attempt is made to provide ceramic layers on the outer diameter surface and width surface of the bearing by the thermal spraying method, it is necessary to thermally spray a layer of nickel aluminum or the like as a base treatment in advance, which also causes a decrease in productivity.

In addition, since the ceramic layer obtained by the thermal spraying method becomes porous, the corrosion resistance and chemical resistance decrease due to moisture intrusion due to dew condensation, etc., so the pores in the ceramic layer are sealed to remove moisture. It is necessary to prevent intrusion. For sealing treatment, a method using a sealing treatment agent containing a synthetic resin, a polymerizable organic solvent, and at least one selected from the group consisting of a fluorosurfactant and a perfluoro group-containing organosilicon compound (see Patent Document 5). Or a combination layer with a sealing layer with a corrosion-resistant / chemical-resistant resin having good permeability as the lower layer and a sealing layer with a corrosion-resistant / chemical-resistant resin with poor permeability as the upper layer. Although a method for making holes (see Patent Document 6) is known, there is a problem that an additional process called a sealing process is required and production efficiency and cost are deteriorated.
JP-A-7-279773 Japanese Patent Laid-Open No. 10-47355 JP-A-8-93774 JP-A-5-106638 Japanese Patent Laid-Open No. 2003-183806 Japanese Patent No. 3009516

  The present invention was made in order to cope with such problems, and formed a dense ceramic layer by a method instead of the thermal spraying method, exhibiting excellent corrosion resistance and chemical resistance against chemicals such as acid and alkali. An object is to provide a rolling bearing for chemical resistance.

The rolling bearing for corrosion / chemical resistance of the present invention comprises an inner ring, an outer ring, and a plurality of rolling elements interposed between the raceways of the inner and outer rings, and is provided on a surface that contacts at least a corrosive substance of the inner ring and the outer ring. An anti-corrosion / chemical-resistant rolling bearing having a ceramic film, wherein the ceramic film is a film formed by an aerosol deposition method (hereinafter referred to as an AD method).
In the present invention, the corrosion resistance / chemical resistance refers to a property that does not cause deterioration of quality such as corrosion, swelling, dissolution, decomposition, etc. even when in contact with chemicals (corrosive substances) such as various acids and alkalis.

The ceramic coating is a coating using alumina fine particles as an aerosol raw material.
The alumina fine particles have an average particle diameter of 0.01 μm to 2 μm. In the present invention, the average particle diameter is a value measured by Nikkiso Co., Ltd .: Laser type particle size analyzer Microtrac MT3000.

  The ceramic coating is formed by fixing an aerosol spray nozzle and moving the outer ring or the inner ring in an axial direction using a positioning XY table while rotating the outer ring or the inner ring using an object rotating motor. To do.

  The corrosion-resistant / chemical-resistant rolling bearing according to the present invention forms a ceramic film by AD method on at least the surfaces of the inner ring and outer ring that are in contact with a corrosive substance, so that the film surface and the raceway ring base can be communicated at room temperature. A dense ceramic film can be obtained, and high corrosion resistance and chemical resistance can be maintained.

  In a vacuum chamber, etc., a motor for rotating the object is installed on the positioning XY table, the aerosol injection nozzle is fixed, and the outer ring or inner ring of the bearing is rotated and moved in the axial direction. The coating can be uniformly formed on the contact surface of the outer ring or the contact surface of the inner ring which is a curved surface. By rotating and recoating the aerosol coating, a dense ceramic coating of several μm to several tens of μm can be formed with good adhesion. In addition, the manufacturing cost is significantly reduced due to the fact that there is no need to cool the workpiece, no base treatment such as nickel aluminum, and no sealing treatment.

  Since the inner ring surface and the outer ring surface are coated with a thin-film ceramic layer, it has higher hardness than a resin film such as PTFE resin, and is excellent in load resistance and wear resistance. Further, when compared with a single PPS resin bearing, the elastic modulus is high, so that the load resistance is excellent.

An embodiment of a rolling bearing for corrosion / chemical resistance according to the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a corrosion / chemical resistant rolling bearing. The ceramic coating is a very thin coating of several μm to several tens of μm, but in FIG. 1, it is shown thicker than the actual thickness for convenience of explanation.
As shown in FIG. 1, the rolling bearing for corrosion / chemical resistance includes a plurality of rolling elements 4 held by a cage 3 between an inner ring 1 and an outer ring 2, and grease sealed around the rolling elements 4. A seal member 8 is provided at both ends of the inner ring 1 and the outer ring 2 in the axial direction, and the outer ring 2 is fixed to the housing 5 and the shaft 6 is fixed to the inner diameter of the inner ring 1. Further, ceramics formed by the aerosol deposition method on the contact surface 1a of the inner ring 1 and the contact surface 2a of the outer ring 2 that constitute a space that contacts the various shafts, the seal member 8, and the housing 5 in contact with various corrosive substances. A coating 7 is provided. The inner ring 1 and the outer ring 2 are made of a metal material such as bearing steel.
In addition, the surface which forms the ceramic film 7 in the inner ring 1 and the outer ring 2 is a surface that contacts at least a corrosive substance of the inner ring 1 and the outer ring 2, and includes a surface that directly contacts and a surface that may contact.

In the present invention, the AD method is a method in which an aerosol in which fine particles of raw material ceramics are dispersed in a gas is sprayed from an aerosol injection nozzle toward a base material such as an inner ring or an outer ring, and the aerosol collides with the surface of the base material at high speed. This is a method of forming a coating film made of the above constituent material 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. . For this reason, the anti-corrosion / chemical-resistant rolling bearings with the coating formed on the contact surface of the inner ring and the contact surface of the outer ring that are in contact with corrosive substances are not affected even if they are exposed to corrosive substances such as acids and alkalis. Since it is protected by a ceramic layer that does not have pores that can penetrate, the corrosive substance does not enter the base material, and the corrosion resistance and chemical resistance are not lowered.
In addition, since the ceramic coating by the AD method is dense and excellent in corrosion resistance and chemical resistance, the film thickness necessary to ensure a certain level of corrosion resistance and chemical resistance can be made thinner than that of the thermal spraying method.

Examples of the ceramic fine particles used as an aerosol raw material for forming a ceramic coating by the AD method in the present invention include oxide ceramic fine particles such as alumina, zirconia, and titania having good corrosion resistance and chemical resistance. 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.
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 Heating fine particles of several tens of nanometers or less produced using 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.

  A bearing in which the inner ring surface and the outer ring surface are coated with a ceramic layer by the above-described AD method has a higher hardness than a PTFE resin film, and therefore has high load resistance and wear resistance. In addition, when compared with a single PPS bearing, the elastic modulus is high, so that the load resistance is excellent.

In the present invention, as a method of forming a ceramic coating by the AD method, a method of forming a coating by fixing a rolling bearing for corrosion resistance and chemical resistance and moving an aerosol spray nozzle, or a method of forming corrosion resistance and resistance by fixing an aerosol spray nozzle. Any method of forming a film by moving a rolling bearing for chemicals can be employed.
Among these methods, aerosol can be sprayed in a stable state, and in combination with an XY table for positioning and a motor for rotating an object, by moving the inner ring or outer ring of the bearing in the axial direction, The latter method is preferably used because the ceramic film can be easily applied by repeated coating.

  The AD method in the present invention will be described with reference to FIG. FIG. 2 is a view showing an apparatus for forming a ceramic film by the AD method. As shown in FIG. 2, the ceramic film forming apparatus 9 by the AD method has a vacuum chamber 10. In the vacuum chamber 10, an outer ring or an inner ring 12 of a rolling bearing for corrosion / chemical resistance, which is a ceramic film formation target, and an aerosol injection nozzle 17 are disposed. Aerosol is supplied from the aerosol generator 16 to the aerosol injection nozzle 17. The inside of the vacuum chamber 10 is depressurized by the vacuum pump 11. In order to prevent mixing of ceramic fine particles, a fine particle filter 18 is provided immediately before the vacuum pump 11. The outer ring or inner ring 12 is rotated in the vacuum chamber 10 by an object rotating motor 14 (A in the figure) and moved in the axial direction by a positioning XY table 13 (B in the figure).

The aerosol spray nozzle 17 sprays ceramic fine particles onto the entire surface of the outer ring or the inner ring 12 from a nozzle tip having an opening such as a rectangle. In addition, the aerosol injection nozzle 17 may be one or plural. Further, the aerosol injection nozzle 17 may be configured to be displaceable in the vacuum chamber 10.
As an aerosol carrier gas, an inert gas is used and supplied from the gas supply facility 15 to the aerosol generator 16. Usable inert gases include argon, nitrogen, helium and the like.
From the fixed aerosol injection nozzle 17, an aerosol made of ceramic fine particles is injected to the outer ring or inner ring 12 rotating at a predetermined number of revolutions by the object rotating motor 14, and is applied to the contact surface of the outer ring or the contact surface of the inner ring. A ceramic film is formed by recoating. At the same time, the outer ring or the inner ring 12 is moved in the axial direction by the positioning XY table 13, whereby a coating film is uniformly formed in the axial direction of the contact surface of the outer ring or the contact surface of the inner ring.
The film formation is preferably performed until the film thickness reaches about 4 μm. If it is less than 4 μm, sufficient corrosion resistance and chemical resistance cannot be obtained, and if it exceeds 200 μm, the production cost increases.

Example Rolling bearings for corrosion and chemical resistance shown in FIG. 1 were prepared and used as test bearings. Here, a coating made of alumina fine particles was formed on the contact surface 1a of the inner ring 1 and the contact surface 2a of the outer ring 2 by the AD method. The AD method uses a bearing drive device that uses both a positioning XY table and an object rotation motor, and moves in the axial direction while rotating at a peripheral speed of 6 mm / min. An alumina fine particle aerosol was sprayed onto the contact surface 2a through a nozzle having an opening size of 5 mm × 0.3 mm under a reduced pressure of 100 Pa or less to form a film. The film was formed until the film thickness reached 4 μm.
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.

  The obtained test bearing was immersed in a chemical solution and rotated at a rotational speed of 2000 rpm for 20 hours. Two types of chemical solutions were tested: 20% by weight each of sodium hydroxide and sulfuric acid. After the test, the chemical contact surface of the bearing was visually checked. As a result, no erosion or damage was observed in any of the chemical solutions, and excellent corrosion and chemical resistance despite the extremely thin coating (4 μm). showed that.

  The rolling bearing for corrosion resistance / chemical resistance of the present invention has a ceramic coating formed by the AD method on at least the surfaces of the inner ring and outer ring that come into contact with a corrosive substance, and therefore can maintain high corrosion resistance / chemical resistance. For this reason, in rolling bearings used for various industrial machines, it can be suitably used as rolling bearings for corrosion resistance and chemical resistance.

It is sectional drawing which shows one Example of the rolling bearing for corrosion resistance / chemical resistance of this invention. It is a figure which shows the ceramic film formation apparatus by AD method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Cage 4 Rolling body 5 Housing 6 Shaft 7 Ceramic film 8 Seal member 9 Ceramic film formation apparatus 10 Vacuum chamber 11 Vacuum pump 12 Outer ring or inner ring 13 Positioning XY table 14 Object rotation motor 15 Gas supply equipment 16 aerosol generator 17 aerosol spray nozzle 18 particulate filter

Claims (4)

An anti-corrosion / chemical-resistant rolling bearing comprising an inner ring, an outer ring, and a plurality of rolling elements interposed between the raceways of the inner and outer rings, and having a ceramic coating on a surface that contacts at least a corrosive substance of the inner ring and the outer ring. There,
The ceramic film is a film formed by an aerosol deposition method, and is a rolling bearing for corrosion resistance and chemical resistance.   2. The rolling bearing for corrosion and chemical resistance according to claim 1, wherein the ceramic coating is a coating using alumina fine particles as an aerosol raw material.   The rolling bearing for corrosion resistance and chemical resistance according to claim 2, wherein the average particle diameter of the alumina fine particles is 0.01 µm to 2 µm.   The ceramic coating is formed by fixing an aerosol injection nozzle and moving the outer ring or the inner ring in an axial direction using a positioning XY table while rotating the outer ring or the inner ring using an object rotating motor. The rolling bearing for corrosion resistance and chemical resistance according to claim 1, claim 2 or claim 3.

Images