JP2013057093A - Sliding member, method for manufacturing the same, and sliding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member capable of securing a lower friction coefficient than that of conventional ones in the atmosphere and a method for producing the sliding member.SOLUTION: The method for producing the sliding member is used for forming an amorphous carbon film containing nitrogen on a surface of a substrate. In the method, by irradiating nitrogen ion beams to the surface of the substrate and irradiating electronic beams to a carbon target in such a way that a plurality of projection parts is formed on the surface of the amorphous carbon film, the amorphous film is formed while a part of the carbon target is deposited on the surface of the substrate.

Description

  The present invention relates to a sliding member having an amorphous carbon film formed on a sliding surface and a manufacturing method thereof, and more particularly to a sliding member excellent in initial adaptability and a manufacturing method thereof.

  Traditionally, tribology has played an important role in Japanese key industries such as the automobile industry. For example, in the automobile industry, various efforts are currently being made to reduce the carbon dioxide emitted from automobiles in order to preserve the global environment. As an example, energy efficient power sources such as hybrid systems are being used. The development of is well known. However, in order to achieve further low fuel consumption, not only the development of the power source but also the reduction of energy transmission loss due to friction in the engine and in the drive system becomes an important issue.

  In view of the above-mentioned problems, a new coating covering the sliding surface of a sliding member made of structural steel or high alloy steel in order to reduce the friction coefficient of the sliding member in power system equipment and improve the wear resistance. Amorphous carbon material (DLC) is attracting attention as a tribological material.

  As an example of a sliding member using such an amorphous carbon material, a silicon nitride film containing silicon is used to replace a part of carbon with silicon to form a film made of a nitrogen carbon silicon material. A moving member is disclosed (for example, refer to Patent Document 1). As another example, a sliding member is disclosed in which a carbon nitride film and a carbon coating film formed on the carbon nitride film are coated on a base material (see, for example, Patent Document 2).

JP 2002-167206 A JP 2009-013192 A

  However, when such a sliding member is used, it is superior in that it has wear resistance as compared with conventional amorphous carbon materials. When sliding in a non-lubricated state (without supplying lubricating oil), the friction coefficient was high and the initial wear was sufficiently large.

  The present invention has been made in view of such problems, and the object of the present invention is not only in a lubrication environment but also in the atmosphere (non-lubricated state) at the initial stage of sliding. An object of the present invention is to provide a sliding member capable of ensuring a lower friction coefficient than before and a method for manufacturing the same.

  In view of the above problems, the present inventors obtained the following new findings as a result of intensive studies. Specifically, when an amorphous carbon film is to be formed on the surface of a substrate using the electron beam evaporation method, the carbon target is irradiated with an electron beam, and a part of the carbon target is melted and evaporated. Then, carbon atoms jump out from the carbon target and deposit on the surface of the substrate.

  Atoms that have jumped out of the carbon target by sputtering such as ion beam sputtering so far have higher energy than atoms that have been evaporated by electron beam. collide.

  However, the atoms jumping out of the carbon target by the electron beam are not faster than the sputtering, but a large amount of carbon atoms are released from the carbon target. As a result, a softer amorphous carbon film can be formed at a higher film formation rate than an amorphous carbon film formed by ion beam sputtering.

  In the present invention, when the electron beam evaporation method is used, the cluster carbon having a large particle size that jumps out from the carbon target while being melted without being evaporated is formed on the surface of the amorphous carbon film. It adheres to the surface of this and becomes a plurality of protrusions (droplets). The hardness of the protrusions is lower (softer) than the hardness of the film surface where the protrusions of the same amorphous carbon film are not formed, and the plurality of protrusions are not slid in the atmosphere. The new knowledge that it contributes greatly to the improvement of the friction characteristic of the moving member was acquired.

  The present invention is based on this new knowledge, and the manufacturing method of a sliding member according to the present invention is a manufacturing of a sliding member in which an amorphous carbon film containing nitrogen is formed on the surface of a substrate. In this method, the surface of the substrate is irradiated with a nitrogen ion beam, and the carbon target is irradiated with an electron beam so that a plurality of protrusions are formed on the surface of the amorphous carbon film. Thus, the amorphous film is formed while depositing a part of the carbon target on the surface of the substrate.

  According to the present invention, an amorphous carbon film is formed while irradiating a nitrogen ion beam toward the substrate surface and depositing a part of the carbon target evaporated by the electron beam on the surface of the substrate. An amorphous carbon film (CNx) containing nitrogen can be formed on the surface (sliding surface) of the base material of the sliding member.

  By irradiating the carbon target with an electron beam, a large amount of carbon atoms is evaporated and emitted from the carbon target as compared with the conventional sputtering method. Thereby, the film-forming speed | rate of an amorphous carbon film can be raised compared with film-forming methods, such as sputtering so far.

  In addition, cluster carbon having a large particle size that jumps out from the carbon target in a molten state without being partially evaporated is deposited on the surface of the substrate and the surface of the film in the film formation stage. A protrusion is formed on the surface.

  Conventionally, when an amorphous carbon film is formed by an arc ion plating method, a laser deposition method, a sputtering method, or the like, the protrusions at the time of film formation have substantially the same hardness as the film surface other than the protrusions. It becomes. Therefore, in general, since the surface of the amorphous carbon film is a sliding surface, it is preferable that the surface is smooth (that is, no protrusions (droplets) are formed).

  However, in the present invention, since the amorphous carbon film is formed by the electron beam evaporation method, the protrusion generated at the time of film formation has a lower hardness than the surface of the amorphous carbon film other than the protrusion. (Ie become soft). Thereby, this soft protrusion part can improve the friction characteristic of the sliding member at the time of sliding.

  Furthermore, the height of the protrusion may be set according to the application location of the sliding member. For example, according to an example of an experiment confirmed by the inventors, the number of sliding is large (the frequency of sliding is high). ), The height of the protrusion is desirably lower, while the height of the protrusion is desirably high at a position where the number of sliding times is small (the frequency of sliding is low).

  In the latter case, as a more preferable embodiment, an amorphous carbon film is formed so that the height of the protrusion is 0.6 μm to 1.0 μm. According to this aspect, when the sliding member is slid in the atmosphere (non-lubricated state), the friction coefficient of the sliding member can be made 0.1 or less from the initial stage of sliding. This is because the protrusions (droplets) are softer than the surface of the coating, so that low shear properties can be expressed with respect to the mating member.

  That is, when the height of the protrusion is lower than 0.6 μm, the protrusion is worn away immediately, and the coefficient of friction cannot be sufficiently reduced in the initial stage of sliding. On the other hand, in the case where a protrusion having a protrusion height exceeding 1.0 μm is to be formed, the film thickness of the amorphous carbon film must be increased. There is a possibility that the coefficient of friction increases in the initial stage of sliding.

  As the present invention, a sliding member having the above-described characteristics is also disclosed. The sliding member according to the present invention is a sliding member for forming an amorphous carbon film containing silicon and nitrogen on the surface of a base material, and a plurality of surfaces are formed on the surface of the amorphous carbon film. A protrusion is formed, and the protrusion is softer than the surface other than the protrusion.

  According to the present invention, since the protrusion of the amorphous carbon film is softer than the surface other than the protrusion, the soft characteristics of the protrusion can improve the sliding characteristics of the sliding member. it can.

  As a more preferable aspect, the height of the protrusion is 0.6 μm to 1.0 μm. According to this aspect, the friction coefficient of the sliding member can be reduced to 0.1 or less at the initial stage of sliding in the atmosphere (non-lubricated state). As described above, when the height of the protruding portion is lower than 0.6 μm, the protruding portion is quickly worn out, and the friction coefficient cannot be sufficiently reduced in the early stage of sliding. On the other hand, when the height of the protrusion exceeds 1.0 μm, the initial wear of the sliding member on which the amorphous carbon film is formed increases, and the friction coefficient at the initial sliding may increase.

  The “nitrogen-containing amorphous carbon film” in the present invention is a so-called CNx film, and may further contain oxygen atoms and hydrogen atoms. And as a more preferable aspect, the hardness of a projection part is 12 GPa or less, and the hardness of the surface of the said amorphous carbon film other than a projection part exists in the range of 14-30 GPa.

  According to this aspect, at the time of sliding, the protrusion flows while flowing on the surface of the sliding member, and the friction coefficient of the sliding member can be lowered. That is, when the hardness of the surface of the amorphous carbon coating other than the protrusions is 12 GPa or less, the coating has insufficient wear resistance, and a coating exceeding 30 GPa cannot be formed. Moreover, when the hardness of a projection part exceeds 12 GPa, it cannot be said that it is soft with respect to the other surface of an amorphous carbon film, and it becomes difficult to express the sliding characteristic mentioned above.

  The sliding member according to the present invention may be used in either a lubricated state or a non-lubricated state, but more preferably, the sliding member manufactured by the above-described sliding member and the above-described manufacturing method is the first. A sliding member that slides on the first sliding member as a second sliding member, and the first and second sliding members slide without lubrication. By employing a moving structure, these sliding members can be slid with low friction.

  According to the present invention, a lower friction coefficient can be ensured at the initial stage of sliding not only in a lubrication environment but also in the atmosphere (non-lubricated state) compared to the past.

The schematic schematic diagram of the manufacturing apparatus for manufacturing the sliding member which concerns on embodiment of this invention. It is the figure which showed the result of having observed the surface of the sliding member (amorphous carbon film) which concerns on Example 1 with atomic force microscope (AFM), (a) is the surface of an amorphous carbon film. It is an AFM image, and (b) is a diagram showing an example of a protrusion formed on an amorphous carbon film. The photograph figure which showed the result of having observed the surface of the sliding member (amorphous carbon film) concerning Example 1 with the electron microscope (SEM). The figure which showed the maximum value of the protrusion part of Examples 1-4, the minimum value, and the average value. The figure which showed the maximum value of the width | variety of the projection part of Examples 1-4, the minimum value, and the average value. The figure which showed the maximum value of the area ratio which the projection part of Examples 1-4 occupies, the minimum value, and the average value. FIG. 7 is a result of a hardness test at an arbitrary point in Examples 1 to 4, and (a) is a diagram showing a load displacement curve in six protrusions satisfying the height of the protrusions of 120 to 800 nm. (B) is the figure which showed the load displacement curve in four places of the film surfaces other than a projection part. The maximum value, minimum value, and average value of the hardness of the protrusion obtained from the curve of FIG. 7A, and the maximum value, minimum value, and average of the hardness of the protrusion other than the protrusion determined from the curve of FIG. The figure which showed the value. The figure for demonstrating a ball-on-disk friction tester. The result of the friction test of the sliding member which concerns on Example 1 is shown, (a) is the figure which showed the relationship between the cycle number of a sliding member, and a friction coefficient, (b) is 5000 cycles. The photograph figure which showed the result of having observed the surface of the amorphous carbon film in SEM with an electron microscope (SEM). The result of the friction test of the sliding member which concerns on Example 2 is shown, (a) is the figure which showed the relationship between the cycle number of a sliding member, and a friction coefficient, (b) is 5000 cycles. The photograph figure which showed the result of having observed the surface of the amorphous carbon film in SEM with an electron microscope (SEM). The result of the friction test of the sliding member which concerns on Example 3 is shown, (a) is the figure which showed the relationship between the cycle number of a sliding member, and a friction coefficient, (b) is 5000 cycles. The photograph figure which showed the result of having observed the surface of the amorphous carbon film in SEM with an electron microscope (SEM). The result of the friction test of the sliding member which concerns on Example 4 is shown, (a) is the figure which showed the relationship between the cycle number of a sliding member, and a friction coefficient, (b) is 5000 cycles. The photograph figure which showed the result of having observed the surface of the amorphous carbon film in SEM with an electron microscope (SEM). The figure which showed the friction coefficient of the sliding initial stage with respect to the height of the projection part which concerns on the sliding member of Examples 1-4, and the friction coefficient in 10000 cycles.

  Embodiments of a sliding member and a manufacturing method thereof according to the present invention will be described below. FIG. 1 is a schematic configuration diagram of an apparatus for manufacturing the sliding member of the present embodiment (forming a film on a base material).

  The manufacturing method of the sliding member of this embodiment is a method of manufacturing a sliding member in which an amorphous carbon film containing nitrogen is formed on the surface (sliding surface) of a base material. Specifically, by irradiating the surface of the substrate with a nitrogen ion beam and irradiating the carbon target with an electron beam so that a plurality of protrusions are formed on the surface of the amorphous carbon film, In this method, the amorphous film is formed while a part of the carbon target is deposited on the surface of the substrate.

  First, a base material for the sliding member is prepared. The material of the base material is not particularly limited as long as the material has a surface hardness and a material that can ensure adhesion with the amorphous carbon coating during sliding. And base materials such as steel, cast iron, aluminum, polymer resin, and silicon.

  In addition, an intermediate layer made of silicon (Si) may be provided on the surface of the base material in order to increase the adhesion between the base material and the amorphous carbon film before forming the amorphous carbon film. Further, chromium (Cr), titanium (Ti), or tungsten (W) may be used instead of silicon.

  By using a film forming apparatus (IBAD (ion beam assisted vapor deposition) apparatus) as shown in FIG. 1 and combining an ion beam mixing method and an electron beam vapor deposition method, an amorphous carbon nitride film is formed on the surface of the substrate. A film is formed (film formation process). First, as shown in FIG. 1, a base material and a carbon target are disposed in a film forming apparatus.

Next, the pressure in the vacuum chamber is reduced using a turbomolecular pump. Specifically, a turbo molecular pump is a turbo molecular pump that exhausts air in a vacuum chamber to bring the chamber into a state close to vacuum (2.0 to 4.0 × 10 ⁻³ Pa). In general, rotary pumps and diffusion pumps are used to obtain this degree of vacuum. However, in order to eliminate the influence of adsorbed oil, a turbo molecular pump that does not use oil is used in order to perform the friction experiment described later. Then, the air in the vacuum chamber is exhausted.

  Next, the substrate is indirectly cooled with cooling water, and the substrate is irradiated with a nitrogen ion beam with a predetermined acceleration energy from a nitrogen ion beam generation source. This cleans the surface of the substrate. Then, the surface of the base material is irradiated with a nitrogen ion beam, and an electron beam having a predetermined output from the electron beam generation source is applied to the carbon target so that a plurality of projections described later are formed on the surface of the base material. Irradiation is performed to melt and evaporate a part of the carbon target, and an amorphous film is formed on the surface of the substrate while evaporating the evaporated carbon on the surface of the substrate.

  Here, the thermocouple shown in FIG. 1 is a measuring instrument for predicting the surface temperature of the base material at the time of film-forming with a thermocouple, and this is used to measure the temperature of the back surface of the base material. The film thickness meter (thickness gauge) is a crystal oscillator type film thickness meter for measuring the film thickness of the deposited amorphous carbon film, and increases with the film formation time using this. The film thickness of the amorphous carbon film to be measured is measured. The principle of this measuring instrument is that the crystal oscillator is oscillated, the weight of the deposited film material is obtained from the change in the natural frequency of the film during film formation, and the volume weight is divided by the film density to obtain the film volume. The film thickness is calculated.

  In this way, the obtained amorphous carbon film is irradiated with a nitrogen ion beam toward the substrate surface, and a part of the carbon target is deposited on the surface of the substrate while the amorphous carbon film is formed. Since the film is formed, an amorphous carbon film (CNx film) containing nitrogen can be formed on the surface (sliding surface) of the substrate.

In the present embodiment, since the substrate is irradiated with a nitrogen ion beam, an amorphous carbon film (CNx film) in which sp ² bonds between carbon and nitrogen are increased can be obtained. The sliding member having this coating (CNx coating) has a lower coefficient of friction than that containing no nitrogen (DLC coating). In addition, the atomic ratio of the content of nitrogen atoms / the content of carbon atoms in the CNx film is not particularly limited, but the above-described low friction can be used as long as the atomic ratio is in the range of 0.1 to 0.25. Characteristic can be expressed.

  By irradiating the carbon target with an electron beam, a larger amount of carbon atoms is evaporated and emitted from the carbon target than in the conventional sputtering method. Speed can be increased.

  In addition, cluster carbon having a large particle size that jumps out from a carbon target in a molten state without being partially evaporated is deposited on the surface of the substrate and the surface of the coating film in the film formation stage. As a result, a plurality of protrusions are formed on the surface of the amorphous carbon film.

  Here, the height of protrusions (droplets) formed on the surface of the amorphous carbon film, the width of the protrusions, and the occupation ratio (area ratio) occupied by the plurality of protrusions with respect to the film surface are It can be adjusted by adjusting the voltage and current supplied to the electron beam and the film formation time. In the present embodiment, the height of the protrusion is a dominant factor of the friction coefficient in the initial sliding stage of the sliding member, so that the height of the protrusion is 0.6 μm to 1.0 μm. Then, an amorphous carbon film is formed.

  As this condition, for example, the output of the electron beam is controlled to 10 kV, 0.7 to 0.9 A, the film formation time is about 20 to 60 minutes, and an amorphous carbon film in such a range is formed. A film can be formed. If the height of the protrusion is manufactured in the above-described range, a protrusion having the width of the protrusion and the area ratio of the protrusion to achieve the effect is formed.

  When an amorphous carbon film is formed by an arc ion plating method, a laser deposition method, a sputtering method or the like as in the prior art, the protrusions at the time of film formation are approximately the hardness of the film surface other than the protrusions. Equivalent and hard. Therefore, in general, in order to increase the coefficient of friction, the surface of the amorphous carbon film is a sliding surface, so that the surface is smooth (that is, no protrusions (droplets) are formed). ) Was preferred.

  However, in this embodiment, since the amorphous carbon film is formed by the electron beam evaporation method, the protrusion generated at the time of film formation is lower in hardness than the surface of the amorphous carbon film other than the protrusion. (That is, soft), it is possible to improve the friction characteristics of the sliding member during sliding.

  In particular, when the amorphous carbon film is formed so that the height of the protrusion is 0.6 μm to 1.0 μm, when the sliding member is slid in the atmosphere (non-lubricated state), From the initial stage of sliding, the friction coefficient of the sliding member can be made 0.1 or less. This is because the protrusions (droplets) are softer than the other coating surfaces, and thus exhibit low shearing properties with respect to the mating member.

  In addition, when the height of the protrusion is 0.3 μm or less, the protrusion is worn out in the initial stage of sliding, but the low protrusion (droplet) is the sliding surface of the amorphous carbon film. A film with good lubricity (low friction coefficient) is formed over time and spreads over time. Thus, in this embodiment, what is necessary is just to select the height of the projection part formed in the surface of an amorphous carbon film according to the use environment of a sliding member.

Hereinafter, the present invention will be described by way of examples.
Example 1
<Production of sliding members>
A film forming apparatus shown in FIG. 1 was used for forming an amorphous carbon film (CNx film) containing nitrogen. First, silicon wear having a (100) orientation on the surface was prepared as a base material. The base material and the carbon target were placed in a vacuum chamber, and the air in the vacuum chamber was evacuated with a turbo molecular pump so that the inside of the chamber became 2.0 to 4.0 × 10 ⁻³ Pa. And the cooling water of 20 degreeC was circulated through the installation base with which the base material was installed, and the temperature of the base material was kept constant.

  Next, the flow rate of nitrogen gas to assist nitrogen ions to the nitrogen ion generation source is set to 10 sccm, the acceleration voltage of assist nitrogen ions becomes acceleration voltage: 1.0 kV (34 mA), and the microwave output of nitrogen assist ions is 0.4 kW ( The nitrogen ion beam generation source was adjusted so that the reflected output was 0 kW. The adjusted normal nitrogen ion beam was irradiated toward the surface of the substrate, and the surface of the substrate was cleaned for 5 minutes.

  Next, under the same conditions as the cleaning conditions, the surface of the substrate is irradiated with a nitrogen ion beam, and the output of the electron beam for electron beam evaporation is applied to the carbon target at a voltage of 10 kV and a current of 0.7 to 0.9 A. An electron beam adjusted to the above range was irradiated to melt and evaporate a part of the carbon target, and a part of the evaporated carbon target was deposited on the surface of the substrate irradiated with the nitrogen ion beam. The film formation time was 4 minutes and 40 seconds, and the film formation rate was 1.0 to 2.0 nm / s and the film thickness was 160 nm by a film thickness meter.

  Thus, a sliding member was obtained in which an amorphous carbon film (CNx film) containing nitrogen was formed on the surface (sliding surface) of the base material.

(Examples 2 to 4)
As in Example 1, a sliding member having an amorphous carbon film formed on a base material was manufactured. The difference from Example 1 is that the film formation time is set to 12 minutes 20 seconds, 32 minutes 00 seconds, 46:00 hours, so that the film thickness of the amorphous carbon film is 370 nm, 1090 nm and 1600 nm. This is the point.

(Comparative Examples 1 and 2)
As in Example 1, a sliding member having an amorphous carbon film formed on a base material was manufactured. Comparative Example 1 is different from Example 1 in that an amorphous carbon film containing nitrogen is formed by sputtering (ion beam sputtering) using an ion beam mixing method. The difference from Example 1 is that an amorphous carbon film (DLC) is formed so that droplets are formed by sputtering.

<Surface observation>
The surface on which the amorphous carbon film of the sliding member of Examples 1 to 4 was formed was observed with an atomic force microscope (AFM) and an electron microscope (SEM), and a protrusion on the surface was formed. confirmed.

  FIG. 2 is a diagram showing the result of observing the surface of the sliding member (amorphous carbon coating) according to Example 1 with an atomic force microscope (AFM). FIG. It is the image of AFM of the surface of a film, (b) is a figure showing an example of the projection part formed in the amorphous carbon film.

  The atomic force microscope is capable of observing the unevenness of the sample surface with a resolution at the nanometer level by using the force acting between the sample and the probe. The apparatus includes a measuring head (NPX100 manufactured by Seiko Instruments Inc.) and a controller (Nanopocs1000 manufactured by Seiko Instruments Inc.). Measurement can be performed at a measurement range of 0.5 nm to 1000 μm and a scanning speed of 12 to 1792 seconds / frame.

  FIG. 3 is a result of observing the surface of the sliding member (amorphous carbon coating) according to Example 1 with an electron microscope (SEM).

  Using the results of the AFM images as shown in FIGS. 2A and 2B, the widths of the 20 protrusions formed on the surface of the amorphous carbon film of the sliding members of Examples 1 to 4 The height was measured, and the height and width of the protrusion were measured. In FIG. 4, the maximum value of the protrusion part of Examples 1-4, the minimum value, and the average value ((circle)) were shown. In FIG. 5, the maximum value of the protrusion part of Examples 1-4, the minimum value, and the average value ((circle)) were shown.

  Furthermore, when evaluating the area ratio of the plurality of protrusions on the surface of the amorphous carbon film using the result of the SEM image as shown in FIG. The area ratio of the part was measured. Three SEM images were measured for each of Examples 1 to 4, and FIG. 6 shows the maximum and minimum values of the area ratio occupied by the protrusions of Examples 1 to 4 and the average value (◯).

[Result 1]
The film thickness of the amorphous carbon film according to Examples 1 to 4, the height of the protrusion (average value), the width of the protrusion (average value), the width of the protrusion (average value), the area ratio of the protrusion ( The average value was as shown in Table 1 below.

<Hardness test>
The load displacement curve when the surface of the amorphous carbon coating in Examples 1 to 4 was subjected to indentation hardness measurement with an AFM nanoindenter manufactured by Hystron was obtained, and the projected area of the indentation trace due to plastic deformation was determined from this load displacement curve. The hardness was calculated by dividing the maximum indentation load by the projected area of the indentation mark.

  FIG. 7 is a result of a hardness test at an arbitrary point in Examples 1 to 4, and (a) shows a load displacement curve in six protrusions satisfying the height h of the protrusions of 120 to 800 μm. (B) shows load displacement curves at four locations on the surface of the coating film other than the protrusions. 8 shows the maximum value, minimum value, and average value of the hardness of the protrusions determined from the curve of FIG. 7A, and the maximum value and minimum of the hardness of the protrusions other than the protrusions determined from the curve of FIG. Values and average values are shown.

[Result 2]
As shown in FIG. 8, the hardness (average value 7.5 GPa) of the protrusions of the amorphous carbon coating is lower than the hardness (average value 14.8 GPa) of the other amorphous carbon coatings. The part was softer than other surfaces. Specifically, the hardness of the protruding portion was 12 GPa or less even at the maximum value, and the hardness of the coating surface other than the protruding portion was 14 GPa even at the minimum value.

[Discussion]
The result 2 was that when the electron beam was irradiated, cluster carbon having a large particle size popping out from the carbon target in a melted state without being partially evaporated was deposited on the surface of the substrate and the film surface in the film formation stage. As a result, it is considered that soft protrusions were formed on the surface of the amorphous carbon film.

<Friction test>
The friction test of Examples 1-4 and Comparative Examples 1 and 2 was performed in the following procedure. First, silicon nitride spheres having a diameter of 8 mm and shown in Table 2 below were prepared.

  A ball-on-disk friction tester shown in FIG. 9 was used. As a preliminary preparation for the wear test, the ball specimen B was ultrasonically cleaned with acetone and ethanol for 10 minutes each. Thereafter, in the chamber 30, the ball test piece B is fixed to the ball holder 35 removed from the main body of the testing machine, and it is confirmed that there is no scratch on the surface using an optical microscope (not shown), and these are then desiccator. (Not shown) was put in, and the ball test piece B was dried. On the other hand, foreign matters such as dust on the surface (sliding surface) of the amorphous carbon coating formed on the surface of the disk test piece D were removed by hand blow (not shown).

  Next, the disc test piece D was held on the disc holder 44, and the ball holder 35 to which the ball test piece B was fixed was attached to the main body of the testing machine so as to be integrated with the stage 31. Using a strain gauge 33 (manufactured by Kyowa Denki Co., Ltd., KF-1-120-C1-16) bonded to the parallel leaf spring 32, the ball test piece B is against the surface of the amorphous carbon coating of the disk test piece D. The stage 31 was adjusted so that a load having a load value of 0.1 N (Hertz average contact pressure (135 MPa)) was applied, and these were brought into contact with each other. The contact position between the ball test piece B and the disk test piece D was determined by the triaxial stage 31, and the vertical load was adjusted by moving the z axis up and down.

  Then, under a dry condition (under dry friction conditions), the atmosphere is introduced into the chamber, the motor 41 is driven to rotate the pulley 42, and the disk test piece of the disk holder 44 in the nitrogen gas atmosphere via the belt 43. D was rotated for 1 minute with respect to the ball test piece B under a constant speed rotation condition in which the radius of rotation was 2 mm and the relative speed (sliding speed) was 42 m / s (number of rotations: 200 rpm).

  The frictional force at this time was measured with the strain gauge 34, and data was taken in and recorded in the computer via the sensor interface (PCD-300A, manufactured by Kyowa Denki Co., Ltd.). And the friction coefficient was converted.

  The results are shown in FIGS. 10 (a) to 13 (a) and FIG. FIG. 10A to FIG. 13A are diagrams showing the relationship between the number of cycles of the sliding member according to Examples 1 to 4 and the friction coefficient, and FIG. It is the figure which showed the friction coefficient of the sliding initial stage with respect to the height of the projection part which concerns on a sliding member, and the friction coefficient in 10,000 cycles. In addition, in FIG.10 (b)-FIG.13 (b), the photograph figure which showed the result of having observed the surface of the amorphous carbon film of Examples 1-4 at the time of 5000 cycles with an electron microscope (SEM), respectively. It is.

[Result 3]
As shown in FIG. 10A, in the case of the sliding member of Example 1, the friction coefficient at the initial stage of sliding is as high as about 0.27, and the friction coefficient is reduced to about 0.13 at 10,000 cycles. It was.

  As shown in FIG. 11 (a), in the case of the sliding member of Example 2, at the initial stage of sliding up to 1000 cycles, the coefficient of friction was less than 0.1, and thereafter around 1500 cycles. From this, the coefficient of friction increased.

  As shown in FIG. 12 (a) and FIG. 13 (a), in the case of the sliding members of Examples 3 and 4, the friction coefficient at the initial stage of sliding is less than 0.1, and thereafter at 10,000 cycles, The coefficient of friction increased.

  Although not shown in the drawing, in the case of the sliding member of Comparative Example 1, the friction coefficient is approximately constant at about 0.15, and in the case of the sliding member of Comparative Example 2, the friction coefficient is about 0.3. It was almost constant.

  As shown in FIGS. 10 (b) to 13 (b), the surfaces of these sliding members were confirmed during the test (at the time of 5000 cycles). As the number of cycles increased, the protrusions on the mating member were cut. I found out.

[Discussion]
As shown in the result 3, as in Examples 3 and 4, when the amorphous carbon film is formed so that the height of the protrusion is 0.6 μm to 1.0 μm, the atmosphere (non-lubricated state) ), When the sliding member is slid, the friction coefficient of the sliding member can be made 0.1 or less from the initial stage of sliding. This is thought to be because the surface of the amorphous carbon coating exhibited low shearing properties with respect to the counterpart member because the protrusions (droplets) were softer than the coating surface.

  Further, as in Example 1, when the height of the protrusion is 0.3 μm or less, the protrusion is worn out at the initial stage of sliding, but the low protrusion (droplet) is amorphous. The film spreads on the sliding surface (surface) of the carbon film, and a film having good lubricity (low friction coefficient) is formed with time.

  Further, in Comparative Examples 1 and 2, the friction coefficient did not fall below 0.1 regardless of the number of cycles. As in the sliding member according to Example 2, the height of the protrusions was 0.4 μm (0. Even in the case of 3 μm to less than 0.6 μm, the friction coefficient may be less than 0.1 at the very initial sliding, so when using the sliding member under such sliding conditions It can be said that the height of this protrusion is suitable. As described above, if the height of the protrusion is selected according to the usage environment of the sliding member, desired friction characteristics can be obtained.

  As mentioned above, although it explained in full detail using embodiment of this invention, a concrete structure is not limited to this embodiment and an Example, There exists a design change in the range which does not deviate from the summary of this invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 31 ... Stage, 32 ... Parallel leaf | plate spring, 33 ... Strain gauge, 35 ... Ball holder, 41 ... Motor, 42 ... Pulley, 43 ... Belt, 44 ... Disc holder, B ... Ball test piece, D ... Disc test piece

Claims (6)

A method for producing a sliding member in which an amorphous carbon film containing nitrogen is formed on the surface of a substrate,
By irradiating the surface of the base material with a nitrogen ion beam and irradiating the carbon target with an electron beam so that a plurality of protrusions are formed on the surface of the amorphous carbon coating, the carbon A method for producing a sliding member, characterized in that the amorphous film is formed while a part of a target is deposited on the surface of the substrate.   The method for manufacturing a sliding member according to claim 1, wherein the amorphous carbon film is formed so that the height of the protrusion is 0.6 μm to 1.0 μm. A sliding member for forming a nitrogen-containing amorphous carbon film on the surface of a substrate,
A plurality of protrusions are formed on the surface of the amorphous carbon film, and the protrusions are softer than the surface of the amorphous carbon film other than the protrusions. Moving member.   The sliding member according to claim 3, wherein a height of the protruding portion is 0.6 μm to 1.0 μm.   The hardness of the said protrusion part is 12 GPa or less, and the hardness of the surface of the said amorphous carbon film other than a protrusion part exists in the range of 14-30 GPa, The Claim 3 or 4 characterized by the above-mentioned. Sliding member.   The sliding member manufactured by the manufacturing method according to claim 1 or the sliding member according to any one of claims 3 to 5 is provided as a first sliding member, and the sliding member is slid on the first sliding member. A sliding structure comprising a moving sliding member as a second sliding member, wherein the first and second sliding members slide in a non-lubricated state.

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