JP2006097871A - Rolling sliding member and rolling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling sliding member and a rolling device having superior lubricating property even under environments not having sufficient moisture and gas such as high vacuum environment, and having superior abrasion resistance and durability. <P>SOLUTION: At least one of a raceway surface 1a of an inner ring 1, a raceway surface 2a of an outer ring 2 and a rolling face 3a of a rolling element 3 of a deep groove ball bearing is coated with a diamond-like carbon film D. The diamond-like carbon film D is composed of three layers, that is, a metallic layer M composed of at least one kind of metals of Cr, W, Ti, Si and Ni, a composite layer F composed of a compound of the metal composing the metallic layer M and carbon, and a carbon layer C composed of carbon, and these three layers are successively arranged in order of the carbon layer C, the composite layer F and the metallic layer M from a surface side. Further hydrogen is included in the carbon layer C, and a ratio (H/C) of the number of carbon atoms C and the number of hydrogen atoms H in the carbon layer C is 0.2-0.5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rolling sliding member and a rolling device that are excellent in lubricity.

  Diamond-like carbon (hereinafter sometimes referred to as DLC) has a surface hardness as high as that of diamond, and a surface friction coefficient of 0.2 or less, which is as small as molybdenum disulfide and fluororesin. Thus, since DLC has a peculiar surface property, it attracts attention as a new lubricating material for rolling and sliding members. Patent Documents 1 to 6 disclose bearings in which DLC is formed by chemical vapor deposition (CVD), plasma CVD, ion beam forming, ion vapor deposition, or the like.

  DLC has the property of improving lubricity by adsorbing moisture, gas, etc. in the atmosphere to the surface, and having excellent lubricity with a friction coefficient of 0.2 or less. Moreover, because of its structure, the plastic deformation hardness is 20 GPa or more, it is excellent in wear resistance. Therefore, it is suitable for lubrication of members used in the atmosphere under the boundary lubrication environment or the environment where the lubricant cannot be used.

However, in an environment where moisture and gas are not sufficiently present, such as in a high vacuum environment, the DLC lubricity cannot be sufficiently improved by the above-described adsorption action. Accordingly, there has been a demand for a DLC that has excellent lubricity even if the above-described adsorption action does not occur and can be used as a lubricant even in a high vacuum environment where moisture and gas are not sufficiently present.
WO99 / 14512 pamphlet Japanese Patent Laid-Open No. 9-147464 JP 2000-136828 A JP 2000-205277 A JP 2000-205279 A JP 2000-205280 A JP 2001-72986 A Surface and Coating Technology120-121, p548-554 (1999)

Bonds between carbon atoms in DLC include sp ² bonds similar to those of diamond and sp ³ bonds similar to those of graphite, and sp ³ bonds are related to hardness. ^Two bonds are said to be related to slidability in the atmosphere. However, in a high vacuum environment, if dangling bonds (unbonded hands) exist, the contact surface becomes active and friction and wear progress.

  The hydrogen content in the DLC film varies greatly depending on the manufacturing method and film forming conditions of the DLC film, and affects the physical properties of the DLC film such as electrical characteristics and mechanical characteristics. And since hydrogen also functions as a dangling bond terminator, it has the effect of suppressing friction and wear in the high vacuum environment described above. Patent Document 7 discloses a sliding member in which a sliding surface is coated with a DLC film having a hydrogen content of less than 30 atomic%.

Further, it has been attempted to inactivate carbon having dangling bonds and hydrogen by using a method such as plasma CVD (see Non-Patent Document 1).
However, such a DLC film has insufficient surface hardness, wear is likely to progress, and durability may be insufficient.
Therefore, the present invention solves the problems of the prior art as described above, and has excellent lubricity and excellent wear resistance even in an environment where moisture and gas are not sufficiently present such as in a high vacuum environment. It is an object of the present invention to provide a rolling sliding member and a rolling device having durability and durability.

  In order to solve the above problems, the present invention has the following configuration. That is, the rolling sliding member according to claim 1 according to the present invention is a rolling sliding member in which a rolling contact surface that is in rolling contact with another member is covered with a diamond-like carbon film, and the rolling contact surface is made of steel. The diamond-like carbon film includes a metal layer made of at least one metal of Cr, W, Ti, Si, and Ni, and a composite layer made of a compound of metal and carbon constituting the metal layer, A carbon layer composed of carbon, and these three layers are arranged in the order of a carbon layer, a composite layer, and a metal layer from the surface side, and the carbon layer contains hydrogen, The ratio H / C of the number C of carbon atoms and the number H of hydrogen atoms in the carbon layer is 0.2 or more and 0.5 or less.

A rolling sliding member according to claim 2 of the present invention is the rolling sliding member according to claim 1, wherein the ratio H / C of the number C of carbon atoms and the number H of hydrogen atoms in the carbon layer. However, it is characterized by becoming larger as it goes from the rolling contact surface side to the surface side.
Furthermore, the rolling sliding member according to claim 3 according to the present invention is the rolling sliding member according to claim 1 or 2, wherein the diamond-like carbon film is formed by sputtering using a non-equilibrium magnetron. The carbon source of the composite layer and the carbon layer is solid carbon and hydrocarbon gas.

  Furthermore, the rolling device according to claim 4 according to the present invention has an inner member having a raceway surface on the outer surface, and a raceway surface facing the raceway surface of the inner member, and is disposed outside the inner member. In the rolling device comprising: an outer member that is formed, and a plurality of rolling elements that are arranged to freely roll between the raceway surfaces, at least of the inner member, the outer member, and the rolling element One is a rolling sliding member according to any one of claims 1 to 3.

The present invention can be applied to various rolling devices. For example, a rolling bearing, a ball screw, a linear guide device, a linear motion bearing, and the like.
Further, the inner member in the present invention means an inner ring when the rolling device is a rolling bearing, a screw shaft when the ball screw is also used, a guide rail when the linear guide device is used, and a linear motion bearing. Means each axis. The outer member is the outer ring when the rolling device is a rolling bearing, the nut when it is a ball screw, the slider when it is a linear guide device, and the outer cylinder when it is also a linear bearing. Each means.

  The rolling sliding member and rolling device of the present invention have excellent lubricity and excellent wear resistance and durability even in an environment where moisture and gas are not sufficiently present such as in a high vacuum environment. .

Embodiments of a rolling sliding member and a rolling device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial longitudinal sectional view showing a configuration of a deep groove ball bearing which is an embodiment of a rolling device according to the present invention, and FIG. 2 shows a portion near the raceway surface of the inner ring in the deep groove ball bearing of FIG. It is the partial expanded sectional view expanded and shown.
The deep groove ball bearing shown in FIG. 1 is rotatable between an inner ring 1 having a raceway surface 1a on an outer peripheral surface, an outer ring 2 having a raceway surface 2a facing the raceway surface 1a on an inner peripheral surface, and both raceway surfaces 1a and 2a. Are provided with a plurality of rolling elements 3 and a retainer 4 that holds the plurality of rolling elements 3 between both raceway surfaces 1a and 2a.

  The inner ring 1, the outer ring 2, and the rolling element 3 are made of steel such as SUJ2. Further, as shown in FIG. 2, at least one of the raceway surface 1a of the inner ring 1, the raceway surface 2a of the outer ring 2, and the rolling surface 3a of the rolling element 3, which are rolling contact surfaces that make rolling contact with other members, It is covered with a diamond-like carbon film D having lubricity. As shown in FIG. 2, the diamond-like carbon film D includes a metal layer M made of at least one metal among Cr, W, Ti, Si, and Ni, and a metal and carbon constituting the metal layer M. And a carbon layer C made of carbon (diamond-like carbon). These three layers are formed from the surface side by the carbon layer C, the composite layer F, The metal layers M are arranged in this order. Further, the carbon layer C contains hydrogen, and the ratio H / C between the number C of carbon atoms and the number H of hydrogen atoms in the carbon layer C is 0.2 or more and 0.5 or less. In FIG. 2, for convenience of explanation, a diagram in which a diamond-like carbon film D is provided only on the raceway surface 1 a of the inner ring 1 is shown.

  Since the raceway surface 1a is covered with the diamond-like carbon film D and the diamond-like carbon film D includes the carbon layer C containing hydrogen, there is not enough moisture and gas as in a high vacuum environment. Excellent lubricity even in the environment. This is because the surface of the carbon layer C (diamond-like carbon film D) is inactivated by hydrogen, and friction and wear are suppressed. The thickness of the carbon layer C is preferably 1 μm or more.

  The diamond-like carbon film D includes a composite layer F and a metal layer M. If the carbon layer C, the composite layer F, and the metal layer M are continuously formed by a technique such as sputtering, the diamond-like carbon film D and the steel constituting the raceway surface 1a can be firmly adhered. In the sputtering method, if the sputtering efficiency of the carbon target is gradually increased and the sputtering efficiency of the metal is gradually decreased, the three layers are successively formed in the order of the metal layer M, the composite layer F, and the carbon layer C. It is possible to form.

  The ratio H / C between the number C of carbon atoms and the number H of hydrogen atoms in the carbon layer C needs to be 0.2 or more and 0.5 or less. Since the hardness is high and the rigidity is increased, wear of the mating member is promoted, and deformation with respect to rolling contact stress is difficult, and as a result, peeling is likely to occur. On the other hand, if it exceeds 0.5, the hardness of the carbon layer C becomes low, so that the diamond-like carbon film D is likely to be worn and the durability may be insufficient.

Further, the ratio H / C of the number C of carbon atoms and the number H of hydrogen atoms in the carbon layer C is preferably increased from the raceway surface 1a side to the surface side. Such a carbon layer C is more excellent in friction characteristics and wear resistance.
Furthermore, the diamond-like carbon film D is preferably formed by sputtering using a non-equilibrium magnetron. The carbon source of the composite layer F and the carbon layer C is preferably solid carbon and hydrocarbon gas.

  As a method for adjusting the hydrogen content in DLC, plasma CVD or plasma source ion implantation is known. However, in this method, it is difficult to form a metal layer. Since the composite layer and the metal layer cannot be formed as in the above-described sputtering method by continuously changing the amount of carbon, the adhesion to the underlying steel is insufficient. There is a problem that it is difficult to control.

In addition, the formation of DLC by the high vacuum ion plating method is problematic because it is difficult to supply hydrogen with a hydrocarbon-based gas.
According to sputtering using a non-equilibrium type magnetron, there is no such problem as described above. For example, when a carbon layer is formed by sputtering, solid carbon and a hydrocarbon-based gas can be used together as a carbon supply source. The hydrogen content in the carbon layer can be controlled. As the hydrocarbon gas, an aliphatic hydrocarbon gas (for example, an alkane hydrocarbon gas such as methane) or an aromatic hydrocarbon gas can be used.

If the sputtering power is reduced and the amount of hydrocarbon-based gas is increased, a carbon layer with a high hydrogen content can be obtained. Conversely, if the sputtering power is increased and the amount of hydrocarbon-based gas is decreased, A carbon layer with a low hydrogen content is obtained.
As described above, the amount of the assist gas can be arbitrarily adjusted at the time of forming the carbon layer, the sputtering power and the bias voltage can be controlled independently, and the metal layer and the composite layer can be formed. It is preferable to form a diamond-like carbon film by sputtering using a balanced magnetron.

In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment.
For example, when the diamond-like carbon film D covers at least one of the raceway surface 1a, the raceway surface 2a, and the rolling surface 3a of the rolling element 3, it improves the wear resistance and durability of the deep groove ball bearing. be able to. Further, among the surfaces of the cage 4, diamond-like carbon is formed on a sliding surface that slides in contact with the inner ring 1, outer ring 2, and rolling element 3 (for example, a pocket surface 4 a that slides in contact with the rolling element 3). The film D may be coated. That is, at least one of the raceway surface 1 a of the inner ring 1, the raceway surface 2 a of the outer ring 2, the rolling surface 3 a of the rolling element 3, and the sliding surface of the cage 4 is coated with the diamond-like carbon film D. Also good. Further, the deep groove ball bearing may be configured not to include the cage 4.

Furthermore, in the present embodiment, a deep groove ball bearing has been described as an example of a rolling device, but the present invention can be applied to various types of other rolling bearings. For example, radial type rolling bearings such as angular contact ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing.
Furthermore, the present invention can be applied not only to rolling bearings but also to various types of various rolling devices. For example, a ball screw, a linear guide device, a linear motion bearing, or the like.

〔Example〕
The present invention will be described with reference to specific examples.
First, the wear resistance of a rolling sliding member provided with a diamond-like carbon film was evaluated by a ball-on-disk friction and wear test. The test method will be described below.
A test ball made of bearing steel SUJ2 is placed on a horizontal test plate made of bearing steel SUJ2, and a vacuum environment is applied while applying pressure (surface pressure 0.7 GPa) in the direction of pressing the test plate to the test ball. Under the vacuum (degree of vacuum 4 × 10 ⁻⁶ Pa), the test ball was rotated in the horizontal direction at a sliding speed of 0.6 m / s (rotational movement time was 10 min). Then, the amount of wear generated on the test flat plate and the test ball was measured. The amount of wear of the test plate was evaluated based on the wear depth measured with a surface roughness meter. Further, the wear amount of the test ball was calculated from the size of the circular wear scar.

  The test flat plate has a disk shape with a diameter of 62 mm and a thickness of 7 mm. The surface of the test flat plate is covered with a diamond-like carbon film having a thickness of 3 mm, and the surface roughness is 0.004 μmRa. The test ball is a ball having a diameter of 9.52 mm. Further, in the ball-on-disk friction and wear test, a lubricant such as grease or lubricating oil was not used.

  Here, a method for forming a diamond-like carbon film on the surface of the test flat plate will be described. The test plate degreased in oil was placed in an unbalanced magnetron sputtering apparatus 504 (hereinafter referred to as UBMS apparatus) manufactured by Kobe Steel, Ltd., and bombarded on the surface for 15 minutes using a sputtering method using argon plasma. did.

  Then, using tungsten and chromium as targets, the two types of metals were sputtered onto the surface to form a metal layer. Next, while continuing the sputtering of these two kinds of metals, the sputtering of carbon using carbon as a target was started. By such sputtering, a composite layer made of metal carbide in which the two kinds of metals and carbon were bonded was formed on the metal layer.

  Furthermore, the sputtering efficiency of carbon was gradually increased while gradually decreasing the sputtering efficiency of the two kinds of metals. At this time, a negative bias voltage was applied to the test plate. Then, the sputtering of the two kinds of metals was finished, and a carbon layer made of diamond-like carbon was formed on the composite layer only for carbon sputtering.

  When forming a carbon layer by performing only carbon sputtering, sputtering was performed using solid carbon and methane gas as a carbon target and controlling the partial pressure of methane gas (amount of methane gas). In such sputtering, the amount of hydrogen contained in the carbon layer can be controlled by adjusting the sputtering power and the amount of methane gas. For example, if the sputtering power is reduced and the amount of methane gas is increased, a carbon layer having a high hydrogen content can be obtained. Conversely, if the sputtering power is increased and the amount of methane gas is decreased, the hydrogen content is increased. A carbon layer with a low content can be obtained.

  The results of the ball-on-disk friction and wear test are shown in FIGS. FIG. 3 is a graph showing the relationship between the hydrogen content in the carbon layer and the wear depth of the test flat plate, and FIG. 4 shows the relationship between the hydrogen content in the carbon layer and the wear amount of the test ball. It is a graph. The hydrogen content in the carbon layer shown in both graphs is the ratio H / C of the number C of carbon atoms and the number H of hydrogen atoms in the carbon layer.

  From the graph of FIG. 3, it can be seen that the wear depth of the test flat plate is small when the hydrogen content in the carbon layer is 0.5 or less. Moreover, it can be seen from the graph of FIG. 4 that the wear amount of the test ball is small when the hydrogen content in the carbon layer is 0.2 or more. From these results, when the hydrogen content in the carbon layer is 0.2 or more and 0.5 or less, the rolling and sliding member even in an environment where moisture and gas are not sufficiently present such as in a high vacuum environment. It can be seen that the wear resistance is excellent.

Next, a rolling test in which a rolling contact surface was coated with a diamond-like carbon film was subjected to a rotation test in a high vacuum environment to evaluate durability. The test method will be described below.
The rolling bearing was placed in a high vacuum environment (degree of vacuum 4 × 10 ⁻⁶ Pa) and rotated at a rotational speed of 3000 rpm while applying an axial load of 50N. The time until the load current by the meter relay reaches an overcurrent was defined as the life.

The rolling bearing is a deep groove ball bearing having an inner diameter of 30 mm and an outer diameter of 62 mm. is there.
The diamond-like carbon film was formed using a UBMS apparatus in substantially the same manner as described above. However, the thickness of the carbon layer was 0.8 μm, the thickness of the composite layer was 1.5 μm, and chromium was used for the metal component of the metal layer and the composite layer. Further, the ratio H / C of the number C of carbon atoms and the number H of hydrogen atoms in the carbon layer is different between the rolling contact surface side portion and the surface side portion, and the H / C of the rolling contact surface side portion is 0. It is 22 or more and less than 0.3, and H / C of the surface side portion is 0.3 or more and 0.5 or less. And the hardness of the rolling contact surface side part of a carbon layer is 20 GPa or more and 30 GPa or less, and the hardness of a surface side part is 2 GPa or more and 4 GPa or less.

  Table 1 shows the results of the rotation test of the rolling bearing. From the results of Examples 1 to 4, when the thickness of the portion where H / C is 0.3 or more and 0.5 or less is 0.7 μm or more, the wear resistance of the carbon layer is excellent, and the rolling bearing has a long life. I understand that there is. Further, from the results of Examples 5 and 6, when the thickness of the portion where H / C is 0.22 or more and less than 0.3 is 0.4 μm or more, the wear resistance of the carbon layer is excellent, and the rolling bearing is long. It turns out that it is a lifetime.

  The thickness and hardness of the carbon layer were measured by interrupting the film formation during the formation of the diamond-like carbon film by sputtering. The thickness was measured by a surface shape measuring instrument for the level difference caused by masking. The hardness was measured using an ultra-fine indentation hardness tester manufactured by Elionix Corporation. It can be measured under the condition of an indentation load of 20 mN, and the hardness can be obtained from the load-unloading curve. However, when measuring the hardness of a thin film having a thickness of 1 μm or less, it is preferable that the indentation load is set to 0.4 to 20 mN and the indentation depth is within the range of the thickness of the carbon layer.

It is a fragmentary longitudinal cross-section which shows the structure of the deep groove ball bearing which is one Embodiment of the rolling device which concerns on this invention. It is the elements on larger scale which expanded and showed the track surface vicinity part of an inner ring among the deep groove ball bearings of FIG. It is a graph which shows the relationship between content of hydrogen in a carbon layer, and the wear depth of a test flat plate. It is a graph which shows the relationship between content of hydrogen in a carbon layer, and the amount of wear of a test ball.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 1a Raceway surface 2 Outer ring 2a Raceway surface 3 Rolling element 3a Rolling surface D Diamond-like carbon film M Metal layer F Composite layer C Carbon layer

Claims (4)

In the rolling sliding member in which the rolling contact surface that is in rolling contact with the other member is covered with a diamond-like carbon film, and the rolling contact surface is made of steel,
The diamond-like carbon film includes a metal layer made of at least one metal of Cr, W, Ti, Si, and Ni, a composite layer made of a compound of metal and carbon constituting the metal layer, and carbon. The carbon layer is composed of three layers, and these three layers are arranged in the order of the carbon layer, the composite layer, and the metal layer from the surface side.
The carbon layer contains hydrogen, and the ratio H / C between the number C of carbon atoms and the number H of hydrogen atoms in the carbon layer is 0.2 or more and 0.5 or less. Sliding member.   The rolling according to claim 1, wherein the ratio H / C of the number C of carbon atoms and the number H of hydrogen atoms in the carbon layer increases from the rolling contact surface side toward the surface side. Sliding member.   The diamond-like carbon film is formed by sputtering using a nonequilibrium type magnetron, and the carbon supply source of the composite layer and the carbon layer is solid carbon and hydrocarbon gas. The rolling sliding member according to claim 1 or 2.   An inner member having a raceway surface on the outer surface, an outer member having a raceway surface opposite to the raceway surface of the inner member and disposed outside the inner member, and rolling between the raceway surfaces A rolling device comprising a plurality of freely arranged rolling elements, wherein at least one of the inner member, the outer member, and the rolling element is according to any one of claims 1 to 3. A rolling device characterized by being a rolling sliding member.

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