JPH07301241A - Anticorrosive bearing - Google Patents

Abstract

PURPOSE:To improve the anticorrosive property of a bearing exposed to a corrosive gas atmosphere, an organic gas atmosphere, water vapor and rainwater when used for a semiconductor manufacturing etching device, a food manufacturing machine, a paper mill or outdoor parking facilities. CONSTITUTION:An nickel electroplated or electroless-plated coat layer 5 is provided on at least one surface of an inner wheel 1, an outer wheel 2, a roller 3 and a holder 4 and a non-porous or black chrome plated coat layer 6 is provided thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching apparatus for semiconductor manufacturing, a food manufacturing machine, a paper manufacturing machine, an outdoor parking facility, a bearing exposed to a corrosive gas atmosphere, an organic gas atmosphere, water vapor, rainwater, etc. Among rolling bearings used in a corrosive environment, the present invention particularly relates to a corrosion resistant bearing that is required to have heat and corrosion resistance (corrosion resistance after heating) and scratch resistance.

[0002]

2. Description of the Related Art For example, in an equipment for handling corrosive gas, such as an etching apparatus in semiconductor manufacturing, in order to prevent corrosion, races, rolling elements, cages, etc. are made of SUS4.
It was made of martensitic stainless steel represented by 40C.

In order to impart corrosion resistance to the races and rolling elements, electroless nickel plating, hard chrome plating, etc., or zinc plating, zinc-iron, zinc-nickel alloy plating, and In some cases, chromic acid dipping treatment (chromate treatment) was performed as a post-treatment for improving the corrosion resistance of these plating layers.

[0004]

Under the corrosive environment as described above, SUS440 which can be used as a race ring material.
Corrosion resistance of stainless steel such as C was insufficient, and the functional deterioration of the bearing due to rust was remarkable. In addition, bearings used in vacuum equipment such as etching equipment generally include gold, silver, lead,
A solid lubricating coating made of molybdenum disulfide, PTFE, etc. is formed, but various coatings for imparting lubricity are thin and lack continuity (whether the surface is completely covered). Therefore, the coating film alone could not be expected to function as a corrosion resistant film.

On the other hand, martensitic stainless steels such as SUS440C are slightly inferior in corrosion resistance to austenitic stainless steels such as SUS304 and are exposed to organic gas, steam, etc. in food manufacturing machines, papermaking machines and the like. In some cases, deterioration of bearing function due to rusting may be observed. In addition, it is more expensive than SUJ2 (bearing steel) material. And, in order to obtain sufficient corrosion resistance by electroless nickel plating, a plating thickness of 20 μm or more is required,
In that case, post-processing is required to improve the dimensional accuracy of the bearing. In addition, when the plating film thickness is suppressed to 2 to 3 μm to prevent deterioration of dimensional accuracy, pinholes in the coating film and other parts that do not completely cover the base material occur, and when moisture or the like adheres, the base material metal ( Galvanic corrosion (a phenomenon in which a local battery is formed by the adhesion of water and a current flows and corrodes) between the iron-based) and the coating metal (nickel), and on the contrary, promotes the corrosion of the base material. . In addition, when heat treatment is applied to increase the wear resistance and hardness of the coating, cracking of the plating layer occurs due to the hardening of the coating, reducing corrosion resistance and treating the bearing steel (SUJ2). In this case, since the tempering temperature (180 ° C.) of the bearing steel is exceeded, the hardness (deformation) of the base material (bearing steel) is lowered, and the result is deformed.

In order to obtain sufficient corrosion resistance with hard chrome plating, a plating thickness of 20 μm or more is required in the same manner, but in that case, the internal stress of the plating film is high, so that cracks occur in the film. , Corrosion resistance may decrease.

As described above, in order to prevent deterioration of the dimensional accuracy of the bearing, it is desirable to keep the plating film thickness small.
In order to reduce the film thickness of zinc plating, zinc-iron, and zinc-nickel alloy plating and to achieve sufficient corrosion resistance, it is necessary to perform a chromic acid dipping treatment to form a chromate film. Usually, the chromate treatment significantly improves the corrosion resistance of these zinc-based plating films, but the heat resistance of the chromate coating remains a problem. That is, it is believed that the chromate film is composed of ZnCrO ₄ and Cr (OH) ₃ · nH ₂ O, but when heat of 60 ° C. or higher is applied to the film, water in the film is lost and Cracks occur and the effect of improving the corrosion resistance of the chromate film is reduced.
It is customary for bearings to have a temperature rise of 60 ° C. or more during operation, and this poor heat resistance is a problem. Moreover, since the hardness of these zinc-based plating films is as low as around Hv100, they are easily scratched, and due to bearing rolling,
Since the coating on the rolling traces was worn, there were cases where the corrosion resistance was reduced at these locations. The object of the present invention is to solve the above problems of the prior art, exposed to etching equipment for semiconductor manufacturing, food manufacturing machinery, paper manufacturing machinery, outdoor parking equipment, etc., corrosive gas atmosphere, organic gas atmosphere, water vapor, rainwater, etc. To further improve the corrosion resistance of the bearing.

[0008]

To achieve the above object, the present invention provides at least one of an inner and outer ring, a rolling element, and a cage.
An electroless nickel plating layer or an electroless nickel plating layer is provided on one surface, and a non-porous chrome plating layer or a black chrome plating layer is provided thereon.

The total film thickness of the above electroless nickel plating or electroless nickel plating layer and non-porous chromium plating layer or black chromium plating layer is 0.3 to 3.0.
μm.

The nickel plating film layer may be an electroless nickel-phosphorus or electroless nickel-boron plating film layer.

[0011]

[Function] At least one surface of the inner and outer races, rolling elements, and cages has an electroless nickel plating or electroless nickel plating coating layer on which a non-porous chromium plating coating layer or a black chromium plating coating layer is formed. The bearings provided have excellent corrosion resistance as bearings used in applications such as food manufacturing machines, paper manufacturing machines, outdoor parking equipment, and the like exposed to organic gas atmospheres, steam, rainwater, and the like.

Bearing steels and the like having the above-mentioned electric nickel plating or electroless nickel plating coating layer and having a non-porous chromium plating coating layer or black chrome plating coating layer thereon are more corrosion resistant than SUS440C and the like. It has excellent corrosion resistance and high corrosion resistance even with a relatively thin film thickness of 3.0 μm or less, and is suitable as a surface-treated coating for bearings.
This is for the following reasons. Since the coating has a two-layer structure, surface defects such as pinholes penetrating the base material are unlikely to occur. That is, when the coating has a relatively thin film thickness of 3.0 μm or less and the coating has a single-layer structure, the surface defects of the coating initially formed are not repaired during the plating treatment even if the plating thickness is increased. It remains as a pinhole on the surface later. On the other hand, when the coating has a two-layer structure composed of two different kinds of metals, since the crystal lattice distances of the two metals are different, the second layer metal newly generates nuclei and starts the coating growth. Therefore, it is considered that the pinhole formed in the first layer is repaired by the metal in the second layer. In addition, since the second layer coating is non-porous, it has excellent shielding properties against corrosive environments. Further, since the coating hardness is higher than that of the zinc-based plating film, it has excellent scratch resistance and wear resistance during rolling of the bearing. further,
No decrease in corrosion resistance due to heating like zinc-based plating is observed.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a first embodiment of the present invention applied to a deep groove ball bearing. (1) is an inner ring, (2) is an outer ring,
(3) is a rolling element, (4) is a cage, (5) is an electric nickel plating or electroless nickel plating coating layer, and (6) is a black chrome plating coating layer.

The inner ring (1), the outer ring (2) and the rolling element (3) are made of bearing steel (SUJ2), and the cage (4) is used.
Is a cold-rolled steel plate.

In the embodiment shown in FIG. 1, the surface of the inner ring (1), the outer ring (2) and the rolling element (3) is coated with an electric nickel plating or electroless nickel plating coating layer (5) and a black chrome plating coating layer (6). In the example shown in FIG.

The electroless nickel-plated coating layer (5) is higher in hardness than the electroless nickel-plated coating layer in terms of hardness, and is suitable for a relatively high load application. The nickel plating film layer may be an electroless nickel-phosphorus or electroless nickel-boron plating film layer. Further, the formation of the black chrome plating coating layer (6) is performed by electrolytic treatment in a black chrome plating bath. The components of this black chrome plating bath consist of chromic acid, a catalyst and auxiliary additives, and many baths have been proposed. The catalyst, acetic acid and its salts, formic acid, propionic acid, organic compounds such as sulfamic acid, and fluoric acid,
Fluoride-based materials such as silicic acid and fluoride are used. And as auxiliary additives, boric acid, iron oxalate,
Nitrate, sucrose, barium salt, etc. are used. The black chrome plating used in the examples of the present invention is Chemron CR (trade name) manufactured by Murata Co., Ltd., and the black chrome plating film formed by this contains about 70% of metallic chrome and is a hydration water of chrome. Oxides, metallic chromium, and chromium oxide were present, and surface cracks were not seen compared to general hard chromium plating, and high corrosion resistance was confirmed. The above black chrome plating layer (6)
Is non-porous and has excellent corrosion resistance, but may be composed of other non-porous chromium plating layer.

The total film thickness of the electroless nickel plating or electroless nickel plating film layer (5) and the black chrome plating film layer (6) can be adjusted depending on the corrosion conditions, but normally, the bearing machining is performed. At times, it is desirable to set the film thickness to 0.3 to 3.0 μm so that the conventional bearing clearance can be obtained without considering the thickness of these coating layers.

As a concrete example of FIG. 1, a deep groove ball bearing, #
Inner ring, outer ring, rolling element (made by SUJ2) and cage (made by cold rolled steel plate) of 608 are electroless nickel plated to a thickness of 2 μm, and then black chrome plated (film thickness 1 μm)
I went. After drying at 60 ° C., these inner ring, outer ring, rolling elements and cage were assembled. A predetermined type of grease was filled in the bearing thus manufactured, and then hermetically sealed seals were attached to both end faces of the bearing. Hereinafter, this is referred to as Example 1. In order to confirm the effect of this Example 1, the following comparative example was manufactured.

<Comparative Example 1> An inner ring having the same shape as that of Example 1,
Outer ring, rolling element (made of SUS440C), cage (SUS3)
A grease (SEB08) manufactured by No. 04) was similarly filled with grease and attached with a seal.

<Comparative Example 2> The same inner ring and outer ring as in Example 1,
After plating the rolling element (made by SUJ2) and the cage (made by cold rolled steel plate) with zinc-iron alloy plating to a thickness of 3 μm,
Immersion in a chromic acid solution produced a yellow chromate coating. After drying at 60 ° C for 10 minutes, grease the same,
The seal was attached.

<Comparative Example 3> The same inner ring and outer ring as in Example 1 were used.
Hard chrome plating was plated to a thickness of 3 μm on the bearings of the rolling elements (made by SUJ2) and the cage (made by cold rolled steel plate).
After drying at 60 ° C. for 10 minutes, grease was enclosed and a seal was attached in the same manner.

<Comparative Example 4> The same inner ring, outer ring, and
Non-porous chromium plating was plated to a thickness of 3 μm on the bearings of the rolling elements (made by SUJ2) and the cage (made by cold rolled steel plate). After drying at 60 ° C for 10 minutes, grease the same,
The seal was attached.

<Comparative Example 5> The same inner ring and outer ring as in Example 1 were used.
The bearings of the rolling elements (made of SUJ2) and the cage (made of cold rolled steel plate) were plated with electroless nickel plating to a thickness of 3 μm. After drying at 60 ° C for 10 minutes, grease the same,
The seal was attached.

The coating hardness of these bearings was measured and the corrosion resistance was evaluated. In the evaluation of the corrosion resistance, a salt spray test (sodium chloride concentration 5%) was performed on the one dried at 60 ° C. for 10 minutes and the one further heated at 150 ° C. for 1 hour.
%, Spray amount 1-2 ml / h, test temperature 35 ° C.). The results are shown in Table 1. (Corrosion resistance evaluation is the time until the occurrence of red rust)

Further, as a result of evaluating the bearing of Example 1 in an actual machine, no deterioration of the bearing function due to wear of the plating layer on the raceway surface, rusting inside the bearing or rust outside the bearing was observed.

[0026]

[0027]

EFFECTS OF THE INVENTION According to the corrosion-resistant bearing of the present invention, which comprises the electroless nickel plating layer or the electroless nickel plating layer and the non-porous chromium plating layer thereon, the base material of the bearing component is inexpensive. Various materials can be used, it has a relatively thin film and high corrosion resistance, and there is no deterioration in corrosion resistance due to heating,
It is not easily scratched, and even if the bearing is rolled under a relatively high surface pressure, the corrosion resistance at the rolling trace is not significantly reduced, and the corrosion resistance as a bearing used in a corrosive environment is outstanding. Can be improved.

The present invention can be similarly applied to a bearing box, a shield, a slinger, a ball screw, a linear bearing, a ball bush, and the like, and in that case, the same action and effect are exhibited.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of the present invention applied to a deep groove ball bearing.

[Explanation of symbols]

1 inner ring 2 outer ring 3 rolling element 4 cage 5 electro nickel plating or electroless nickel plating coating layer 6 black chrome plating coating layer

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[Procedure amendment]

[Submission date] May 2, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

[0026]

[Table 1]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // C25D 3/08

Claims (3)

[Claims] 1. At least one of an inner and outer ring, a rolling element, and a cage.
A corrosion-resistant bearing, comprising an electroless nickel plating layer or an electroless nickel plating layer on one surface, and a non-porous chrome plating layer or a black chrome plating layer thereon. 2. The total film thickness of the electroless nickel plating or electroless nickel plating film layer according to claim 1 and the non-porous chromium plating film layer or the black chromium plating film layer is 0.3 to 3.0 μm. A corrosion-resistant bearing characterized in that 3. A corrosion-resistant bearing, wherein the nickel plating film layer according to claim 2 is an electroless nickel-phosphorus or electroless nickel-boron plating film layer.