JP2003148487A - Rolling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling device capable of achieving excellent corrosion resistance to chemical liquid having strong corrosiveness used for cleaning semiconductor wafers or the like. SOLUTION: An outer ring 11 and an inner ring 12 are formed of α+β- or β-titanium alloy, and surface hardness of it is set to be within a range of Hv 250-Hv 400.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling device such as a rolling bearing, a ball screw and a linear guide used in a wafer cleaning device, a food machine, a chemical plant, a photo developing machine and the like.

[0002]

2. Description of the Related Art A rolling device such as a rolling bearing is generally constructed by arranging a large number of rolling elements between an outer member and an inner member. The rolling element rolls between the outer member and the inner member when one of them rotates or moves linearly.

The outer member and inner member of such a rolling device are usually made of a steel material such as high carbon chrome bearing steel and case hardening steel, but in recent years, they are corrosion resistant to water, seawater and the like. In order to improve the rolling resistance, rolling devices in which the outer member and the inner member are made of stainless steel have also appeared. However, there are various environments in which rolling devices are used, and even stainless steel may lack corrosion resistance. For example, in a wafer cleaning apparatus used in a semiconductor manufacturing process, a strong acid solution such as sulfuric acid or hydrochloric acid or a mixed solution of ultrapure water mixed with ammonia water and hydrogen peroxide solution is used as a cleaning solution. The cleaning liquid has a very strong corrosiveness to steel materials.
Therefore, when the rolling device as described above is used in the wafer cleaning device, corrosion of the outer member and the inner member progresses, and metal ions eluted by the corrosion may become impurities and contaminate the wafer. is there.

Therefore, it has been considered to use a resin-based material as a material for forming the outer member and the inner member of the rolling device. However, the resin-based material has low strength and is easily deformed. It is not suitable as a constituent material for the outer member and the inner member of the rolling device to which a load is applied. Further, as a rolling device in which the outer member and the inner member are made of a metal material having excellent corrosion resistance, there is a rolling device disclosed in JP-A-11-223221. However, the one disclosed in the above publication is
As a constituent material of the outer member and the inner member, since a titanium alloy in which the α phase is precipitated in the matrix of the β phase by aging treatment is used, it shows high corrosion resistance against strong acids such as sulfuric acid and hydrochloric acid, Corrosion resistance is weak against special cleaning liquids used for cleaning wafers, such as a mixture of ultrapure water mixed with ammonia water and hydrogen peroxide water, or a low-concentration hydrofluoric acid-based cleaning liquid. This may corrode the titanium alloy.

[0005]

As described above, when a titanium alloy is used as a constituent material of the outer member and the inner member, it is possible to obtain excellent corrosion resistance as compared with steel materials such as stainless steel. However, the corrosiveness of the outer member and the inner member may be deteriorated with respect to the chemical solution used for cleaning the wafer.

Therefore, the present invention has been made in view of such problems, and provides a rolling device which can obtain excellent corrosion resistance even to a chemical used for cleaning a wafer. The purpose is to

[0007]

In order to achieve the above object, the invention of claim 1 is a rolling device constituted by arranging rolling elements between an outer member and an inner member. The outer member and / or the inner member is formed of α + β type titanium alloy or β type titanium alloy, and Hv250-4
It has a surface hardness of 00.

According to a second aspect of the present invention, in the rolling device according to the first aspect, after the outer member and / or the inner member is subjected to a solution treatment on a titanium alloy that has been turned into a predetermined shape. It is characterized in that it is formed by aging treatment. According to a third aspect of the present invention, in the rolling device according to the first aspect, an oxide film containing TiOx (x = 1 to 2) is formed on a surface of the outer member and / or the inner member in contact with the rolling element. It is characterized by having.

According to a fourth aspect of the present invention, in the rolling device according to the first aspect, the rolling element is formed of ceramics. According to a fifth aspect of the present invention, in the rolling device according to the first aspect, there is provided a cage made of resin for holding the rolling element.

[0010]

[Function] Since titanium alloy is a metal with excellent corrosion resistance,
When this is used as a material for forming the outer member and the inner member of the rolling device, the outer member and the inner member are not likely to be corroded by a solution of sulfuric acid, hydrochloric acid, nitric acid, etc.
The cleaning liquid used for cleaning the semiconductor wafer (for example, a mixed liquid of ammonia and hydrogen peroxide in ultrapure water or a low-concentration hydrofluoric acid-based solution) may be corroded.

Titanium alloy is strengthened by heat treatment. As a method thereof, solution treatment is performed on the titanium alloy, and then aging treatment is performed with the matrix structure as a single phase structure of β phase to form α phase of about several μm. Titanium alloy strengthening is achieved by microprecipitation. In this case, the β-phase, which is the matrix structure, dissolves the alloy element in titanium, but the α-phase hardly dissolves the alloy element. Therefore,
When the precipitation of the α phase progresses by the aging treatment, the alloy elements are discharged by diffusion as the aging α phase is formed, and the alloy elements (for example, Mo, V, Cr) that improve the corrosion resistance are concentrated in the β phase of the matrix structure. It As a result, the aging α phase and β
A local cell is formed at the interface with the phase, and the interface between the β phase of the matrix structure and the aged α phase becomes the corrosion occurrence site.

When the age hardening of the titanium alloy proceeds and the maximum hardness is obtained, the precipitation amount of the aging α phase is 3 by volume ratio.
It increases to 0 to 60%, and with this, the area of the interface between the β phase and the α phase increases, resulting in a structure in which corrosion easily progresses. Also, depending on the aging treatment conditions, the aging α may occur at the β-phase grain boundaries.
The phases are deposited in the form of a film and are more likely to corrode. Corrosion cannot be suppressed if a large amount of α-phase is precipitated.Therefore, it is possible to suppress the precipitation of α-phase by aging treatment, or to suppress the degree of age hardening to reduce the amount of α-phase precipitation. The hardness of titanium alloy to Hv250-H
Since the β phase can be made the main constituent phase by suppressing to v400, and the formation of the local battery is suppressed by this, the ammonia water, the hydrogen peroxide solution, and the ultrapure water used for cleaning the wafer can be separated from each other. Corrosion resistance is remarkably improved even with a mixed solution or a low-concentration hydrofluoric acid-based cleaning solution.

In particular, in order to minimize the amount of corrosion, it is most preferable to have a β-phase single-phase structure, that is, a uniform structure in the as-solution-treated state. In addition, in order to increase hardness while ensuring corrosion resistance, aging treatment
The precipitation hardening of the phase may be used. In this case, as a method of increasing the hardness of the titanium alloy, the precipitation amount of the α phase is controlled to about 10 to 30% so that the hardness does not exceed Hv400, or the aging treatment temperature is lowered to form the intermediate transition layer. Examples of the method include finely precipitating the ω phase and hardening.

In the latter method of precipitating the ω phase, the alloy concentration in the ω phase is almost the same as the alloy concentration in the β phase before the aging treatment, because the alloy elements are not so much diffused and moved during the precipitation of the ω phase. Since the local battery is not formed unlike the case where the α phase is deposited, the hardness of the titanium alloy can be improved and the corrosion resistance can be maintained. Although the maximum hardness cannot be obtained by suppressing the age-hardening amount of the titanium alloy, as described later, if the hardness is controlled to about Hv 200 to 400, the tensile strength is 800 to 1200 MPa.
Some strength is obtained. Since this strength is significantly higher than that of resin bearings used in conventional semiconductor wafer cleaning equipment, it can be used without causing problems such as deformation even under high load conditions. You can

When the solution heat treatment temperature is kept below the transformation point of α / β and the titanium alloy is cooled, the hardness of the titanium alloy is below Hv250 and the pro-eutectoid α phase having a large particle size is obtained. It becomes a β-phase mixed structure. In this case, many interfaces between the α phase and the β phase are formed, and corrosion is likely to proceed from the interface between the α phase and the β phase, as in the case where the age hardening is advanced, which is not suitable. Further, when the cooling rate is slow as in the case of furnace cooling, coarse α phase is precipitated inside or at the boundary of β phase, and corrosion resistance is reduced, which is not suitable.

The titanium alloy used for the outer member and inner member of the rolling device is, for example, Ti-6Al-4V, T.
i-3Al-2.5V, Ti-6Al-2Sn-4Zr
Α + β titanium alloy such as -6Mo, or Ti-15
Mo-5Zr, Ti-15Mo-5Zr-3Al, Ti
-15V-3Sn-3Al-3Cr, Ti-10V-2
Fe-3Al, Ti-3Al-8V-6Cr-4Zr,
Β-type titanium alloy such as Ti-22V-4Al is desirable,
The alloy components are not limited to the above. In particular, the alloy components are not limited to those described above as long as the alloy composition provides a β single phase by solution treatment.

When seizure resistance and wear resistance are required, the titanium alloy is heat-treated in the atmosphere,
An oxide film made of TiOx (x = 0 to 2) is formed on the surface of the titanium alloy, and the slidability of the titanium alloy surface is improved. In this case, the oxidation treatment temperature in the atmosphere is 20
A dense oxide film can be formed by heating and holding at 0 ° C. to 500 ° C. for about 2 to 10 hours.

Further, the corrosion resistance of the titanium alloy is exhibited by the passivation film formed on the surface of the titanium alloy. By forming the above-mentioned oxide film on the surface of the titanium alloy, the corrosion resistance is further improved as compared with the untreated case. Also, Ti
Ceramic coatings such as N, TiCN, TiC, and TiAlN and DLC (diamond-like coating) are suitable for improving wear resistance and seizure resistance.

The cage used in the rolling device according to the present invention is preferably made of resin because it is required to have corrosion resistance. Regarding the resin material of the cage, fluorine-containing resin, polyetheretherketone (PEEK), copolymer of polyetheretherketone and polybenzimidazole (PEEK)
-PBI), polyphenylene sulfide (PPS),
Thermoplastic polyimide (TPI), polyether nitrile (PEN), thermoplastic aromatic polyamide-imide, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / ethylene copolymer (ETFE), tetrafluoro ethylene·
Hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene / ethylene copolymer (ECTFE),
Polyvinylidene fluoride (PVDF) and the like are suitable.

Solid lubricants added to these resins include tetrafluoroethylene resin powder (PTFE), graphite,
Hexagonal boron nitride (hBN), fluoromica, melamine cyanurate (MCA), amino acid compound having a layered crystal structure (N-lauro / L-lysine), fluorinated graphite, fluorinated pitch, molybdenum disulfide (MoS ₂ ) , At least one of tungsten disulfide (WS ₂ ) can be used. Among them, PTFE, MAC, graphite, N-lauro
When L-lysine, hBN, and fluoromica are used alone or in combination of two or more, more preferable lubrication characteristics are obtained.

As for the rolling elements, ceramic-based rolling elements are suitable when corrosion resistance is required. Specifically, ceramic-based materials such as silicon nitride-based, SiC, sialon, alumina-based, and partially stabilized zirconia-based materials are suitable.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a rolling bearing according to an embodiment of the present invention. As shown in the figure,
The rolling bearing according to the present embodiment is configured such that the outer ring 11 as an outer member, the inner ring 12 as an inner member provided inside the outer ring 11, and the inner ring 12 and the outer ring 11 are rollable. The outer ring 11 is provided with a plurality of spherical rolling elements 13 arranged and a retainer 14 that holds the spherical rolling elements 13 in the circumferential direction of the outer ring 11 and the inner ring 12 at substantially constant intervals.
The inner ring 12 is formed by turning an α + β-type or β-type titanium alloy into a predetermined shape, and then subjecting it to solution treatment and aging treatment under the following conditions. Also, the outer ring 11 and the inner ring 1
2 has a surface hardness of Hv250 to Hv400,
An oxide film made of TiOx (x = 0 to 2) is formed on the surfaces (race surfaces) of the outer race 11 and the inner race 12 that are in contact with the rolling elements 13. The rolling element 13 is made of ceramics such as silicon nitride, and the cage 14 is made of fluororesin. <Solution treatment> A titanium alloy bearing ring that has been turned is heated under the conditions of heating temperature: 730 to 950 ° C, heating time: about 1 hour, heating atmosphere: Ar gas atmosphere, and then gas cooling or furnace cooling. <Aging treatment> The solution-treated titanium alloy bearing ring is heated under the conditions of heating temperature: 350 ° C to 500 ° C, heating time: 5 to 60 hours, heating atmosphere: pressure of 1 x 10 ^-2 Pa or less in vacuum or air. After heating, cool the furnace.

In the rolling bearing according to the present invention, the surface hardness of the titanium alloy bearing rings 11 and 12 is set to Hv250 to Hv.
The reason why it is set to 400 is a result derived from the following experiment. That is, the present inventor manufactured bearing rings of rolling bearings (deep groove ball bearings 608) using the materials shown in Table 1, and after subjecting them to solution treatment and aging treatment under the above conditions, the surface hardness of each bearing ring was measured. Was measured with a micro Vickers hardness tester. Further, each produced titanium alloy bearing ring was immersed in ammonia + hydrogen peroxide solution + pure water, and a radial load: 98.0N, axial load: 19.6N was measured using the bearing rotation tester shown in FIG. After rotating each test bearing 1 × 10 ^{7 under} the conditions of rotation speed: 1000 rpm and lubrication: no lubrication, the amount of corrosion of the raceway surface was measured by weight change. In FIG. 2, reference numeral 20 is a test bearing, 21 is a bearing jig, 22 is a motor, and 2 is a bearing.
3 is a rotary shaft, 24 is an axial load control spring, and 25 is a radial load load wire. In Table 1, the raceway surface hardness and the corrosion amount ratio of each test bearing obtained by the above-mentioned Vickers hardness test and bearing rotation test are shown. Show. The corrosion amount ratio of each test bearing is shown in Comparative Example No. Evaluation was made based on the ratio when the corrosion amount ratio of 8 was 1.

[0024]

[Table 1]

In Table 1, N is an embodiment of the present invention.
o. The test bearings 1 to 7 have a raceway surface hardness of Hv40.
The range is 0 or less, and each has a long life. This is because by controlling the surface hardness of the raceway surface to Hv 400 or less, the interface between the α phase and the β phase where corrosion is likely to occur is reduced. In particular, when the β single-phase structure is used, the amount of corrosion is small. In addition, No. 1 is an example when an oxide film is formed on the surface. The test bearing of No. 2 has further improved corrosion resistance. When the ω phase was precipitated, No. Like the test bearing of No. 3, the hardness can be increased while reducing the amount of corrosion, so that it is suitable as a bearing ring material.

On the other hand, in Comparative Example No. 8-11
Is a case where a titanium alloy bearing ring was subjected to age hardening treatment at Hv 400 or more, and No. 1 which is an example of the present invention.
Compared with Nos. 1 to 7, the corrosion weight loss is large and it is unsuitable as a bearing ring material. This is because a large amount of α phase is precipitated by age hardening and corrosion progresses at the interface between the α phase and the β phase. No. which is a comparative example. 12 and 13 have a surface hardness H of the raceway surface.
Although it is v250 or less, in this case, since the corrosion weight loss increases, it is unsuitable as a bearing ring material. When the titanium alloy is cooled from the solution treatment temperature in the furnace, the α phase precipitates at a temperature below the transformation point during cooling, and when it becomes a two-phase structure of α phase and β phase and Hv 250 or less, the volume of the α phase This is not suitable because the rate is increased, the α / β phase interface is increased, and the amount of corrosion is increased.

FIG. 3 shows the relationship between the hardness and the corrosion amount shown in Table 1. As can be seen from FIG. 3, the hardness of the raceway surface is Hv
In the range of 250 to Hv400, the amount of corrosion is small and it can be suitably used. That is, the corrosiveness is remarkably improved even with a highly corrosive chemical solution used for cleaning semiconductor wafers. From the above, by subjecting the solution-treated titanium alloy to an aging treatment and setting its surface hardness to Hv 250 to 400, the corrosiveness with respect to the chemical liquid used for cleaning semiconductor wafers is improved, so that rolling A rolling bearing that can be suitably used as a bearing ring material and has excellent corrosion resistance can be obtained.

In the above-described embodiment, the case where the present invention is applied to the rolling bearing is illustrated, but the present invention is not limited to this, and the present invention is applied to, for example, a ball screw or a linear guide. it can. In this case, the outer member means a nut when the rolling device is a ball screw and the slider when the linear guide is a linear guide, and the inner member means a screw shaft when the rolling device is a ball screw, In the case of a linear guide, it means a guide rail.

[0029]

As described above, according to the present invention,
It is possible to provide a rolling device that can obtain excellent corrosion resistance even with a highly corrosive chemical solution used for cleaning semiconductor wafers and the like.

[Brief description of drawings]

FIG. 1 is a sectional view of a rolling bearing according to an embodiment of the present invention.

FIG. 2 is a view showing a rotation tester used when testing the corrosion resistance of a rolling bearing.

FIG. 3 is a diagram showing a relationship between a raceway surface hardness of a titanium alloy raceway ring and a corrosion weight loss.

[Explanation of symbols]

11 outer ring 12 inner ring 13 rolling elements 14 cage 20 Test bearing 21 Bearing jig 22 motor 23 rotation axis 24 Axial load control spring 25 radial load wire

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3J101 AA02 AA32 AA42 AA52 AA62                       BA01 BA10 BA21 BA50 BA51                       BA53 BA54 BA70 CA34 DA05                       DA14 EA32 EA33 EA34 EA37                       EA42 EA43 EA44 FA08 GA28                       GA53 GA55

Claims (5)

[Claims] 1. A rolling device configured by arranging rolling elements between an outer member and an inner member, wherein the outer member and / or the inner member is an α + β type titanium alloy or β. Type titanium alloy and Hv
A rolling device having a surface hardness of 250 to 400. 2. The outer member and / or the inner member is formed by subjecting a titanium alloy that has been turned into a predetermined shape to a solution treatment and then subjecting it to an aging treatment. The rolling device according to claim 1. 3. The outer member and / or the inner member has TiOx (x = 1 to 1) on a surface in contact with the rolling element.
2. An oxide film containing 2) is included.
The rolling device described. 4. The rolling device according to claim 1, wherein the rolling element is made of ceramics. 5. The rolling device according to claim 1, wherein the rolling device has a resin cage that holds the rolling element.