JPH06249397A - Lubricating member for vacuum and manufacture thereof - Google Patents

Abstract

PURPOSE:To indicate slide characteristics wherein a friction factor in a vacuum is low, stable, and excellent even when the thickness of a molybdenum disulfide baked film is below a specified value. CONSTITUTION:In a lubricating member, such as a gear, used in a way that a surface is coated with a solid lubricant in a vacuum, such as artificial vacuum environment and a space, the solid lubricant with which the surface is coated is 3mum or less in thick, the component contains an inorganic binder containing 17wt.% or more, and the rest is a baked film consisting only of molybdenum disulfide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface modification technique for a lubricating member used in an artificial vacuum environment such as an analytical instrument or in a vacuum such as outer space. The present invention relates to a vacuum lubrication member suitable for use in outer space where the allowable range of dimensional change is strictly limited.

[0002]

2. Description of the Related Art Conventional solid lubricant treatments for vacuum lubricating members include, for example, ion plating of soft metals such as gold, silver, and lead, an organic binder-bonded molybdenum disulfide firing film, and an inorganic binder. There are those in which a bonded molybdenum disulfide baked film is formed and those in which molybdenum disulfide is sputtered.

Of these, the most used one is
It is a molybdenum disulfide firing film for relatively large parts such as gears and sliding bearings, except for relatively small parts that require dimensional accuracy such as rolling bearings and are in the sputtering equipment because they are related to molybdenum disulfide. Has been used (for example, JP-A-59-168055).
No. 4,244,653).

[0004]

However, in such a conventional molybdenum disulfide fired film, the optimum film thickness is about 10 μm, and the minimum film thickness is said to exceed 3 μm, which is thinner than this. Then it was said that the performance did not come out. In fact, even in the experiment by the present inventor, it was forced to 2 μm.
An attempt was made to perform a sliding test by applying a fired film to a level thin film, but the torque was so rough that stable sliding characteristics could not be expected.

Therefore, there is a problem in that it cannot be applied to parts having strict dimensional accuracy and parts in which positional fluctuation and angular fluctuation caused by wear of the fired film during use pose a problem.

That is, for example, in a communication antenna mounted on a space satellite, the surface of the gear used for changing the angle is worn by about 10 μm corresponding to the film thickness of the solid lubricant, and the angle of the antenna is accordingly increased. However, even if the difference is 0.1 degrees, it will be a large deviation from the target several hundred kilometers ahead, and the countermeasure against it is a big problem.

Therefore, molybdenum disulfide sputtering has been mainly used for the members requiring the dimensional accuracy and the wear resistance. However, in order to perform sputtering, first, a member that is large enough to fit in the sputtering device, and a jig that matches the shape of the member (for example, in the sputtering device It was necessary to prepare a rotating device of the above), so that even if the film thickness is 3 μm or less, a lubrication for vacuum coated with a molybdenum disulfide baked film that has a small wear coefficient and is stable and has good sliding characteristics. There was a problem that the development of members was desired.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. Even when the thickness of the molybdenum disulfide fired film is 3 μm or less, the friction coefficient in vacuum is small and stable. And has good sliding characteristics, parts that are not needed for sputtering equipment, parts that have strict dimensional accuracy, and parts that cause positional fluctuations and angular fluctuations caused by abrasion of the baked film during use. It is an object of the present invention to provide a vacuum lubricating member that can be applied to the above.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a solid lubricant applied to the surface of a lubricating member such as a gear used by applying the solid lubricant to the surface in a vacuum such as an artificial vacuum environment or outer space. It is characterized in that it has a thickness of 3 μm or less, a component thereof is 17% by weight or more of an inorganic binder, and the rest is a fired film consisting essentially of molybdenum disulfide.

In the embodiment, the base material of the lubricating member is titanium or a titanium alloy, and the solid lubricant is anodized in an acid bath such as a sulfuric acid bath or a phosphoric acid bath as a pretreatment for applying the solid lubricant. Surface roughness of base material is Rmax
It can be 1 μm or less.

Further, in the method for manufacturing a vacuum lubricating member according to the present invention, titanium or titanium alloy is used as the base material, and the base material is washed in hydrofluoric acid as a base treatment before applying the solid lubricant to the surface. After that, anodizing treatment is performed in an acid bath such as a sulfuric acid bath or a phosphoric acid bath, and a molybdenum disulfide firing film with an inorganic binder binding with an inorganic binder such as sodium silicate is used as a firing film to be applied on the anodizing treatment. The film is substantially free of additives, and the thickness of the solid lubricant applied to the surface is 3 μm or less, the component of which is 17 wt% or more of an inorganic binder and the balance is substantially molybdenum disulfide. It is characterized in that the lubricating member has a fired film made of only.

[0012]

In the vacuum lubricating member according to the present invention, in order to obtain a good life and a stable friction coefficient even under the condition that the thickness of the solid lubricating baked film applied to the surface is thin, first, For the purpose of making the film thickness 3 μm or less, the surface roughness after the treatment is Rma as the base treatment of the substrate.
x is a surface treatment that can be suppressed to 1 μm or less,
Moreover, it has been found that it is preferable to apply an anodizing treatment as a base treatment having a surface treatment layer that is compatible with the solid lubricating film (MoS ₂ ).

Further, even in a film thickness of 3 μm or less, in order to sufficiently stabilize the friction coefficient, the additive component is not substantially contained, and the inorganic binder and the solid lubricating film (MoS are not included).
₂ ) only.

Molybdenum disulfide (MoS ₂ ) is a flake-like particle (fish scale shape). In particular, in order to prevent the components from being separated by gravity in the solvent stage before coating the baked film, the additive is fine. Cannot be used. Therefore, when a thin film is used, the torque becomes rough. It is considered that this is due to the large spherical particles used as the additive as compared with the ratio of the film thickness. In general, the thinner the film, the shorter the life, and at the same time, the sliding torque becomes considerably rough. In the present invention, a sliding property is obtained that is substantially free of additives and can be sufficiently used in a thin film in a vacuum such as outer space.

In the present invention, the film thickness of the solid lubricant capable of obtaining sufficient sliding characteristics is 3 μm or less, preferably 3 to 1
μm. The content of the inorganic binder is 17% by weight or more, preferably 17 to 85% by weight, and in this range, a sufficiently good friction coefficient and a long life can be obtained.

[0016]

EXAMPLES Examples of the present invention will be described below together with comparative examples.

Example 1 Using a Ti-6Al-4V alloy, which is a titanium alloy, as a base material, ultrasonic cleaning was performed for 3 minutes in a 3% hydrofluoric acid solution, and then anodization was performed under the following conditions.

Anodizing condition: Bath component: 35 g / L Sulfuric acid bath Current density: 1 A / dm ² Treatment time: 5 minutes By the above pretreatment, the surface roughness of the substrate is Rmax 1.
A surface of less than μm was obtained.

Further, after the above anodic oxidation treatment, a 30% by weight contained sodium silicate-bonded molybdenum disulfide fired film as an inorganic binder was applied to a film thickness of 2 μm to obtain a test piece of Example 1.

Comparative Example 1 In Example 1, a polyamide-bonded molybdenum disulfide fired film containing 35% by weight as an organic binder was formed to a film thickness of 3 μm.
Comparative Example 1 was carried out in the same manner as in Example 1 except that it was applied to m.
The test piece of was obtained.

Comparative Example 2 In Example 1, except that graphite and diantimony trioxide (Sb ₂ O ₃ ) were added in an amount of 35% by weight as additives,
A test piece of Comparative Example 2 was obtained in the same manner as in Example 1.

Comparative Example 3 Comparative Example 1 except that 35 wt% of diantimony trioxide (Sb ₂ O ₃ ) was added as an additive.
A test piece of Comparative Example 3 was obtained in the same manner as in.

[0023] In Example 1, except using a molybdenum disulfide baking film of 17 wt% containing silicate soda binding as an inorganic binder, in the same manner as in Example 1 to obtain a test piece of Example 2.

[0024] In Example 3 Example 1, except using a molybdenum disulfide baking film of 29 wt% containing silicate soda binding as an inorganic binder, in the same manner as in Example 1 to obtain a test piece of Example 3.

Example 4 In Example 1, a sodium silicate-bonded molybdenum disulfide firing film containing 38% by weight as an inorganic binder was formed to a film thickness of 3
A test piece of Example 4 was obtained in the same manner as in Example 1 except that the test piece was applied to a thickness of μm.

[0026] In Comparative Example 4 Example 1, except for applying the molybdenum disulfide baking film of 9 wt% containing silicate soda binding as an inorganic binder, in the same manner as in Example 1 to obtain a test piece of Comparative Example 4 .

Test Example 1 The sliding characteristics of the test pieces obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated by a pin / disk tester shown in FIG. In the pin / disk tester shown in FIG.
Reference numeral 1 is a disk made of a test piece, 2 is a heater, 3 is a rotary shaft for holding the test piece 1, 4 is a motor for rotating the rotary shaft 3, and 5 is a pin or a ball (here, a ball) sliding on the test piece 1. 6 is a pin or a ball holding member for holding the ball 5, 7 is a link for applying a load L, and 8 is a strain gauge.

The evaluation conditions by this pin / disk tester are shown below.

Pin: SUS440C 5/16 inch ball Load: 10N Speed: 0.5 m / s (298 rpm) Atmosphere: In vacuum (5 × 10 ⁻⁷ Torr or less) Temperature: Room temperature In this evaluation test, the pin / disk tester was used. Is made of martensitic stainless steel SUS
The friction coefficient and the sliding life were measured by using the balls 440C made without the lubrication treatment and using the disk 1 having the titanium alloy surface subjected to the above treatments for the test.

The friction coefficient was measured as a value obtained by dividing the friction torque measured by the strain gauge 8 by the load L. Further, the sliding life was measured by using the cumulative number of rotations until the friction coefficient reached 0.3 as the life.

The coefficient of friction of MoS ₂ is
The coefficient of friction of the metal base material is 0.1 or less, and it is about 0.5 in the case of titanium although it differs depending on the material. In general, the coefficient of friction of 0.15 to 0.3 is used as the standard for breaking the solid lubricating film, and therefore the judgment of breaking of MoS ₂ was measured as the cumulative number of rotations until the coefficient of friction exceeds 0.3. .

FIG. 2 shows the measurement result of the friction coefficient in vacuum, and FIG. 3 shows the evaluation result of the life of each sample in vacuum. From the results shown in FIGS. 2 and 3, the samples of Examples 1 to 4 have a small friction coefficient, a small fluctuation range of the friction coefficient, and a large number of sliding times until the friction coefficient reaches 0.3. Therefore, by applying the treatment of the present invention, even a thin fired film having a film thickness of 3 μm or less can be sufficiently used in an artificial vacuum environment or a vacuum such as outer space, and has excellent sliding characteristics and a long sliding property. It was confirmed that the life and

On the other hand, Comparative Example 1 using an organic binder, Comparative Example 2 using graphite or diantimony trioxide as an additive, and Comparative Example 4 containing a small amount of inorganic binder.
Since the coefficient of friction is large, the fluctuation range of the coefficient of friction is large, and the number of sliding times until the coefficient of friction reaches 0.3 is small, it is well-suited in an artificial vacuum environment or in a vacuum such as outer space. It was hard to say what could be applied.

[0034]

According to the present invention, although the thickness of the molybdenum disulfide fired film is 3 μm or less, which is extremely small,
It has a small coefficient of friction in a vacuum and is stable, and can be applied to parts with strict dimensional accuracy and parts in which positional fluctuation and angular fluctuation caused by wear of the fired film during use pose problems. Provided is a lubricating member for vacuum, which can sufficiently secure a sliding life generally required in outer space. And, by using titanium or titanium alloy as the base material of the lubricating member for vacuum according to the present invention, martensitic stainless steel (for example, SUS440C) and bearing steel, which are generally used in the present space, can be used. Unlike iron-based materials, it is possible to achieve a weight reduction of about 43%. Therefore, it can be used not only as a bearing for vacuum equipment such as an electron microscope and a physical vapor deposition (PVD) device, but also as a lubricating member for space equipment which needs to be lightened. Not only is it applicable to members that require step accuracy, but the size of the parts is not limited as in the case of sputtering, which is a remarkably excellent effect.

[Brief description of drawings]

FIG. 1 Pins used to evaluate sliding properties of test pieces /
It is explanatory drawing which shows the outline | summary of a disk tester.

FIG. 2 is a graph showing a measurement result of a friction coefficient in vacuum.

FIG. 3 is a graph showing the evaluation results of life in vacuum.

Claims (3)

[Claims] 1. In a lubricating member such as a gear used by applying a solid lubricant to the surface in a vacuum such as an artificial vacuum environment or in outer space, the thickness of the solid lubricant applied to the surface is 3
A lubrication member for vacuum, characterized in that it is a fired film having a thickness of not more than μm, the component of which is 17% by weight or more of an inorganic binder and the balance is substantially composed of molybdenum disulfide. 2. The surface of the base material of the base material of the lubricating member is titanium or a titanium alloy, which is anodized in an acid bath such as a sulfuric acid bath or a phosphoric acid bath as a pretreatment for applying a solid lubricant. The lubricating member for vacuum according to claim 1, wherein the roughness is Rmax 1 μm or less. 3. A base treatment using titanium or a titanium alloy as a base material and applying a solid lubricant to the surface,
After cleaning the base material in hydrofluoric acid, anodizing it in an acid bath such as a sulfuric acid bath or phosphoric acid bath, and applying it as a baked film with an inorganic binder such as sodium silicate. The thickness of the solid lubricant applied to the surface is 3 μm or less, and the composition contains an inorganic binder of 17% by weight or more. A method of manufacturing a lubricating member for vacuum, characterized in that the remaining portion is a lubricating member having a fired film consisting essentially of molybdenum disulfide.