JP2021055126A - Nitrogen-containing carbon film, production method thereof, compressor and slide member - Google Patents

Abstract

To provide an amorphous carbon film in which a nitrogen content exceeding 11 atom% is achieved; and to provide a production method of such an amorphous carbon film; and to thereby reduce friction sufficiently.SOLUTION: In an amorphous CNx film 2 applied to a substrate 1, and containing nitrogen, a nitrogen content is 12-20 atom%, and a Young's modulus is 160-250 GPa. In production of the CNx film 2, while irradiating the substrate 1 with a nitrogen ion beam by using a gridless ion beam generator 40, carbon is vapor-deposited onto the substrate 1 by a filtered cathodic vacuum arc method.SELECTED DRAWING: Figure 3

Description

The present invention relates to a nitrogen-containing carbon film, a method for producing the film, a compressor, and a sliding member.

It is known that an amorphous carbon film containing nitrogen is formed on the surface of a base material in order to reduce the loss in the sliding portion (Patent Document 1).
In Patent Document 1, as a method for manufacturing a member that slides in an environment where a lubricating oil is present, the surface of the base material is subjected to a filtered arc deposition method while irradiating a nitrogen ion beam toward the surface of the base material. It is described that an amorphous carbon film having a nitrogen content of 2 to 11 atomic% (at%) is formed by depositing carbon.
According to the description of Patent Document 1, when a sliding member on which an amorphous carbon film is formed is used, nitrogen on the surface of the film is desorbed on the sliding surface, and the sliding surface has a structural change such as graphite. Layers are formed. The coefficient of friction is reduced by this structural change layer.

Patent No. 6298019

According to the description of Patent Document 1, if the nitrogen content is increased to exceed 11 atomic%, it is difficult to form a film. Further, even if a film can be formed, the hardness of the amorphous carbon film is lowered, so that the familiar effect exhibited by the difference in hardness between the structural change layer and the hard layer cannot be sufficiently exhibited.

It is an object of the present disclosure to sufficiently reduce friction by providing an amorphous carbon film having a nitrogen content of more than 11 atomic% and providing a method for producing such an amorphous carbon film.
In addition, by providing a sliding member having an amorphous carbon film having a nitrogen content of more than 11 atomic% and being subjected to a refrigerant atmosphere, and a compressor for a refrigerant containing such a sliding member. The purpose is to sufficiently reduce friction in sliding members used in a refrigerant atmosphere.

The nitrogen-containing carbon film of the present disclosure is an amorphous nitrogen-containing carbon film that is applied to a base material and contains nitrogen, and the nitrogen content of the carbon film is 12 to 20 atomic%, and the carbon film has a nitrogen content of 12 to 20 atomic%. The Young rate is 160-250 GPa.

The method for producing a nitrogen-containing carbon film of the present disclosure is a method for producing an amorphous carbon film containing nitrogen by being applied to a base material, and the nitrogen ion beam is used as a base material using a gridless ion beam generator. Carbon is deposited on the substrate by the filtered Casodic vacuum arc method while irradiating the substrate.

The compressor of the present disclosure is a compressor that compresses a refrigerant containing hydrogen, and includes a sliding member having a nitrogen-containing amorphous carbon film applied to a base material, and the sliding member is a refrigerant. Arranged in an existing atmosphere, the nitrogen content in the carbon film is 12-20 atomic%.

The sliding member of the present disclosure is a sliding member constituting a compressor that compresses a refrigerant containing hydrogen, and is arranged in an atmosphere in which the refrigerant is present, and an amorphous carbon film containing nitrogen is used as a base material. The nitrogen content in the carbon film is 12 to 20 atomic%.

The sliding member of the present disclosure is a sliding member used in an atmosphere in which a refrigerant is present, and an amorphous carbon film containing nitrogen is applied to a base material, and the nitrogen content in the carbon film is determined. It is 12 to 20 atomic%.

The method for manufacturing a sliding member of the present disclosure is a method for manufacturing a sliding member which contains a base material having an amorphous carbon film containing nitrogen and is used in an atmosphere in which a refrigerant is present. A gridless ion beam generator is used to irradiate the substrate with a nitrogen ion beam while depositing carbon on the substrate by a filtered Casodic vacuum arc method.

According to the present disclosure, it is possible to realize a nitrogen-containing amorphous carbon film (hereinafter referred to as CNx film) in which the nitrogen content is increased to 14 to 20 atomic%, as compared with the case where the nitrogen content is smaller. Even if the hardness of the carbon film is reduced, the friction can be sufficiently reduced based on the test results described later.
In addition, increasing the nitrogen content to 14-20 atomic% reduces the Young's modulus of the CNx film to 160-250 GPa, resulting in the Young's modulus of metallic materials typically used for substrates ( A Young's modulus equivalent to (around 200 GPa) will be given to the CNx film. Therefore, it is possible to prevent the CNx film from cracking and peeling from the substrate.
Furthermore, if the CNx membrane of the present disclosure is used in a hydrogen-containing refrigerant atmosphere, the combination of carbon and hydrogen produces a soft polymer-like carbon on the surface of the CNx membrane, and thus under boundary lubrication. Can also reduce friction.

It is sectional drawing of the base material of the sliding member which concerns on embodiment. A CNx film is applied to the base material. It is a graph which shows the relationship between the nitrogen flow rate at the time of film formation, and the nitrogen content of the film about the CNx film shown in FIG. It is a graph which shows the nitrogen content and the friction coefficient under the refrigerant atmosphere about the CNx film shown in FIG. It is a graph which shows the hardness and Young's modulus with respect to the nitrogen flow rate at the time of film formation about the CNx film shown in FIG. It is a schematic diagram which shows the manufacturing apparatus for manufacturing the CNx film shown in FIG. It is a schematic diagram which shows the gridless ion beam generator provided in the manufacturing apparatus shown in FIG. It is a top view which shows the anode provided in the gridless ion beam generator shown in FIG. It is a top view which shows the cathode provided in the gridless ion beam generator shown in FIG. It is a conceptual diagram which shows the plasma generation by the gridless ion beam generator shown in FIG. It is a conceptual diagram which shows the plasma irradiation by the gridless ion beam generator shown in FIG. It is a schematic diagram which shows the ion beam generator including a grid for comparison with the gridless ion beam generator shown in FIG. It is a schematic diagram which shows the relationship between the voltage and the current density of each of the gridless / grid-bearing ion beam generators. It is a figure which shows the manufacturing procedure of the CNx film. It is a figure which shows the surface analysis result by the reflection spectroscopy. It is a figure which shows the surface analysis result by the reflection spectroscopy. It is a figure which shows the surface state of various carbon films from the extinction coefficient and the refractive index. It is a figure which shows the friction characteristic of the CNx film under the dry condition of a refrigerant gas atmosphere. It is a figure which shows the friction characteristic of the CNx film under the refrigerant gas atmosphere boundary lubrication condition. It is a vertical cross-sectional view which shows an example of the compressor which compresses a refrigerant. It is a partially enlarged view of a compressor and shows a thrust plate. It is a perspective view of the thrust plate interposed between a scroll compression mechanism and a thrust bearing. It is a perspective view of the Oldham link. It is a vertical cross-sectional view which shows another example of the compressor which compresses a refrigerant. It is a figure which shows the cylinder, the piston rotor, and the blade which constitute the rotary compression mechanism shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
(Characteristics of CNx film applied to the base material)
FIG. 1 schematically shows a cross section of a base material 1 of a sliding member 10 according to the present embodiment. An amorphous carbon film 2 containing nitrogen is applied to the surface 1A (sliding surface) of the base material 1. Hereinafter, the nitrogen-containing amorphous carbon film 2 applied to the base material 1 will be referred to as a CNx film 2.

The base material 1 is typically formed of a metal material, but can be formed of an appropriate material such as resin or ceramic.
The "CNx film" is a ta-C (tetrahedral amorphous-Carbon) film rich in sp3 structure and corresponds to a nitrogen-containing film (ta-CNx). The thickness T of the CNx film 2 is, for example, 0.1 to 1 μm.

As shown in the upper part of FIG. 1, the CNx film 2 is formed on the base material 1. After that, when the sliding member 10 is used, nitrogen is separated from the surface of the CNx film 2 due to the shearing of the CNx film 2 due to the sliding between the sliding member 10 and the mating member, and carbon is replaced with carbon instead of the separated nitrogen. As shown in the lower part of FIG. 1, a structural change layer 2A containing a structure such as graphite is formed on the surface layer of the base material 1. The hardness of the structural change layer 2A is lower than the hardness of the hard layer 2B in which nitrogen is maintained in the CNx film 2.

Since the bond between nitrogen and carbon in the nitrogen-containing CNx film 2 is inferior to the bond between carbon and carbon in a typical DLC (Diamond-Like Carbon) film, it can be used as a refrigerant in a refrigerant atmosphere. The contained hydrogen and the carbon of the CNx film 2 are likely to be bonded. A chemical reaction between hydrogen in the refrigerant and carbon in the CNx film 2 causes a polymer-like carbon (tribo film) that is soft to the hard layer 2B to be formed on the surface layer of the CNx film 2. It has been confirmed by surface analysis by reflection spectroscopy that polymer-like carbon is formed on the surface layer of the CNx film 2 when used in a refrigerant atmosphere.

In the refrigerant atmosphere, the structural change layer 2A may contain graphite or a similar structure due to the release of nitrogen and polymer-like carbon due to the bond between hydrogen and carbon. When a soft layer (structural change layer 2A) is formed on the surface layer of the CNx film 2, the shearing force during sliding is reduced, so that a friction reducing effect is exhibited.

The nitrogen content in CNx Membrane 2 reaches up to 12-20 atomic%, as shown in FIG. In FIG. 3, the data of 14.5 atomic% and 17.4 atomic% are plotted.
Here, the nitrogen content of the nitrogen-containing amorphous carbon film in the present specification refers to the nitrogen content when the total of carbon and nitrogen is 100 atomic%.
As will be described later, a gridless type ion beam generator 40 is used to irradiate the base material 1 with a nitrogen ion beam, and the base material 1 is subjected to a filtered Cathodic Vacuum Arc (FCVA) method. By depositing carbon to form the CNx film 2, the nitrogen content of the CNx film 2 can be increased to 12 to 20 atomic%.
The nitrogen content of the CNx membrane 2 can be adjusted by setting the flow rate of the nitrogen gas introduced into the gridless ion beam generator 40. As the flow rate of nitrogen gas increases, the partial pressure of nitrogen increases, so that the nitrogen content can be increased.

As shown in FIG. 3 from the results of the ring-on-disk friction and wear test, the CNx film 2 causes friction between the sliding member 10 and the mating member, especially when used in an atmosphere in which a refrigerant is present. It can be sufficiently reduced.
The data shown in FIGS. 12, 13, 15, and 16 were also obtained by the ring-on-disk friction and wear test.
As used herein, the term "refrigerant" refers to a gas-phase or liquid-phase refrigerant containing hydrogen such as an HFC (Hydro Fluoro Carbon) -based refrigerant, an HFO (Hydro Fluoro Olefin) -based refrigerant, ammonia, and a hydrocarbon-based refrigerant. Shall be. The refrigerant may be dissolved in the lubricating oil, or the lubricating oil may be mixed in the refrigerant gas.

FIG. 3 shows the friction coefficient of the CNx film 2 in a rectangular (■) plot in an atmosphere in which lubricating oil is mixed in the refrigerant gas, and shows the friction coefficient of the CNx film 2 in a refrigerant gas atmosphere in a dry condition in which the lubricating oil is not mixed. It is shown in a diamond-shaped (◆) plot. The two plots shown in diamonds in FIG. 3 correspond to Examples 2 and 3 (FIG. 15) described later, respectively. The rectangular plot shown in FIG. 3 corresponds to Example 4 (FIG. 16) described later, and relates to an atmosphere in which a polyol ester (POE) -based lubricating oil is mixed with the refrigerant gas. Regarding the data shown in FIG. 3, the material of the base material 1 is SUJ2 (JIS G 4805: 2008 high carbon chrome bearing steel).
The CNx film 2 exhibits a low coefficient of friction of 0.04 or less regardless of whether the refrigerant gas atmosphere is dry or the refrigerant gas atmosphere is mixed with lubricating oil.

As the nitrogen content increases, the hardness and Young's modulus of the CNx film 2 decrease. The horizontal axis of the graph shown in FIG. 4 represents the flow rate of nitrogen gas introduced into the gridless ion beam generator 40 described later. SCCM (Standard Cubic Centimeter per Minute) is a volumetric flow rate under constant temperature and pressure (standard conditions).
In FIG. 4, the hardness of the CNx film 2 is shown by a solid line, and the Young's modulus of the CNx film 2 is shown by a broken line. For the range of 5 to 40 SCCM, the hardness of CNx film 2 is 18 to 25 GPa, and the Young's modulus of CNx film 2 is 160 to 250 GPa. 5 SCCM corresponds to a nitrogen content of 14.5 atomic% and 40 SCCM corresponds to a nitrogen content of 17.4 atomic%.

The CNx membrane 2 with the nitrogen content increased to 12 to 20 atomic% can be realized by using the gridless ion beam generator 40. Therefore, if the nitrogen content is lower than that, the grid can be used. It can be considered that an ion beam generator containing the above is used. The CNx film formed using an ion beam generator containing a grid has a low nitrogen content and a high hardness. From such a viewpoint, in the above-mentioned Patent Document 1 (Patent No. 6298019), an ion beam irradiation device including a grid is used. Patent Document 1 discloses that the nitrogen content of the nitrogen-containing amorphous carbon film is 2 to 11%, and the hardness thereof is 25 to 80 GPa.

(Manufacturing of CNx film)
In order to manufacture the CNx film 2 applied to the base material 1, the manufacturing apparatus 3 shown in FIG. 5 is used. The manufacturing apparatus 3 is a combination of the FCVA film forming apparatus 30 and the gridless type ion beam generator 40, and by supplying carbon and nitrogen to the substrate 1, the CNx film 2 is attached to the substrate 1. To form a film.

The FCVA film forming apparatus 30 includes a vacuum arc discharge generating unit 31, a filter unit 32, a droplet collecting unit 33, and a vacuum chamber 34 in which the base material 1 is arranged.
The vacuum arc discharge generation unit 31 generates a vacuum arc discharge at a carbon target 312 (cathode) such as a graphite target as a carbon supply source by detonation by the trigger 311 and generates carbon plasma by the arc discharge.
The filter unit 32 includes a plurality of solenoid coils 321 and functions as an electromagnetic filter. The filter unit 32 deflects the ionized carbon toward the vacuum chamber 34 in which the base material 1 is arranged with respect to the droplet traveling from the carbon target 312 toward the droplet collecting unit 33. In the example shown in FIG. 5, the duct 322 of the filter unit 32 is orthogonal to the path of the droplet and forms a T-shape, but the present invention is not limited to this, and for example, a Y-shape may be formed.
The filter unit 32 extracts fine carbon particles for droplets of about 0.1 to several μm and deposits them on the base material 1 in the vacuum chamber 34.

The gridless ion beam generator 40 ionizes the nitrogen gas and irradiates the nitrogen ion beam toward the base material 1. The flow rate of nitrogen gas introduced into the gridless ion beam generator 40 from a nitrogen source (not shown) is appropriately set according to a predetermined nitrogen content of the CNx film 2 formed on the substrate 1.
As shown in FIG. 6, the gridless ion beam generator 40 does not include a grid electrode. The gridless ion beam generator 40 includes an anode 41, a cathode 42 (42A, 42B), and a permanent magnet 43. As the anode 41 is shown in FIG. 7A and the cathode 42 is shown in FIG. 7B, the anode 41 and the cathode 42 are arranged close to each other in the direction orthogonal to the paper surface (the irradiation direction of the ion beam). According to the examples shown in FIGS. 6, 7A and 7B, a permanent magnet 43 is arranged around the anode 41 formed in an annular shape, and in a plan view, the cathode 42A is arranged around the anode 41, and the anode 41 is arranged. The cathode 42B is arranged inside.
When a voltage is applied between the anode 41 and the cathode 42, plasma is generated in the nitrogen gas introduced into the chamber 44 to ionize the nitrogen gas as shown in FIG. 8A, and the nitrogen ion is ionized as shown in FIG. 8B. Is irradiated as a nitrogen ion beam from the outlet 45 between the cathodes 42A and 42B to the base material 1 in the vacuum chamber 34 (FIG. 5). The action of plasma generation shown in FIG. 8A and the action of plasma irradiation shown in FIG. 8B occur simultaneously at the place where the anode 41 and the cathode 42 are arranged.

In the present embodiment, the direction in which the carbon particles are supplied to the vacuum chamber 34 toward the base material 1 and the direction in which the nitrogen ion beam is irradiated toward the base material 1 intersect (orthogonal in the example shown in FIG. 5). doing. As the holder 341 rotates in the vacuum chamber 34, the plurality of base materials 1 installed in the holder 341 move around the rotation axis of the holder 341, so that carbon particles are formed with respect to each of the plurality of base materials 1. And the nitrogen ion beam are supplied alternately.
However, when the position of the member of the gridless ion beam generator 40 and the position of the member of the FCVA film forming apparatus 30 do not interfere with each other, the direction in which the carbon particles are supplied toward the base material 1 and the base material 1 It does not necessarily have to intersect the direction in which the nitrogen ion beam is irradiated. The nitrogen ion beam may be irradiated toward the base material 1 from the same direction in which the carbon particles are supplied toward the base material 1. In this case, the carbon particles and the nitrogen ion beam are simultaneously supplied to the same base material 1.
In the present embodiment, the film formation process can be performed on a plurality of base materials 1 installed on the rotatable holder 341 at one time. However, the film forming process may be performed on a single base material 1.

In order to compare with the gridless ion beam generator 40, FIG. 9 shows a grid type ion beam generator 70. The grid-type and microwave-type ion beam generator 70 includes a microwave source 71, a discharge tube 72, an igniter 73 (igniter), a permanent magnet 75, a grid 74 provided at the outlet of the discharge tube 72, and the like. I have. The nitrogen gas introduced into the discharge tube 72 is ionized by the energy of the microwave emitted from the microwave source 71 and introduced into the discharge tube 72, and accelerated by the grid 74 including a plurality of porous electrodes to which a voltage is applied. Then, it is irradiated to the base material 1 in the vacuum chamber 34 (FIG. 5) as a nitrogen ion beam.
The grid 74 includes, for example, three electrodes stacked at predetermined intervals. The functions of plasma generation and plasma irradiation by the grid 74 are separated between these electrodes.
On the other hand, in the gridless ion beam generator 40, since the anode 41 and the cathode 42 are arranged close to each other, plasma generation and plasma irradiation are performed at the same time.

In FIG. 10, the current density with respect to the voltage of the ion beam emitted by the gridless ion beam generator 40 is shown by a solid line, and the current density with respect to the voltage of the ion beam irradiated by the ion beam generator 70 provided with the grid 74 is shown by a broken line. Shown. From FIG. 10, the gridless ion beam generator 40 has a wider energy width of the ion beam than the grid type ion beam generator 70. Assuming that the current densities are the same, the gridless ion beam generator 40 can flow a larger amount of current (higher current value) than the grid type ion beam generator 70, and therefore has a high output. The set values in the grid type ion beam generator 70 are 3 k V, 0.33 A, 100 W as an example, while the set values in the gridless ion beam generator 40 are 2 k V, 1 A, 1200 W as an example. Is.
As a result, by using the gridless ion beam generator 40, a nitrogen content of 12 to 20 atomic% can be realized. When the grid type ion beam generator 70 is used, the nitrogen content that can be realized in the nitrogen-containing amorphous carbon film remains at about 11 atomic%.

By irradiating the base material 1 with a nitrogen ion beam using the gridless ion beam generator 40 and supplying carbon particles to the base material 1 by the FCVA method using the FCVA film forming device 30, for example, the base material 1 is supplied with carbon particles. A CNx film 2 having a thickness of about 0.5 μm can be formed.

(Example of film formation)
Next, an example of a procedure for forming the CNx film 2 on the base material 1 using the above-mentioned manufacturing apparatus 3 will be described.
In order to improve the quality of the CNx film 2, the carbon target 312 is cleaned (step S3) and the base material 1 is cleaned (steps S1 and S4) as shown in FIG. 11 before the film forming step S5 is performed. Is preferable.

As a preliminary preparation, the base material 1 is immersed in each of benzene and acetone, and ultrasonic cleaning is performed for, for example, 15 minutes (step S1).
The base material 1 that has been ultrasonically cleaned is placed in the holder 341 in the vacuum chamber 34, and the inside of the vacuum chamber 34 is ^{evacuated until, for example, 4 × 10 -4} Pa or less (step S2).

In order to remove impurities and oxides on the surface of the carbon target 312, the surface of the carbon target 312 is cleaned for, for example, 2 minutes by generating an arc discharge in the carbon target 312 by the FCVA film forming apparatus 30 (step S3). At this time, only a part of the solenoid coils 321 (for example, 321A to 321D in FIG. 5) are used, and the remaining solenoid coils 321 are not used. Therefore, the carbon particles are not deflected toward the base material 1 in the vacuum chamber 34, and go straight from the carbon target 312 to the droplet collecting portion 33.

The base material 1 is cleaned by the gridless ion beam generator 40 (step S4). At this time, instead of the nitrogen gas introduced at the time of film formation, argon gas is introduced into the gridless ion beam generator 40 from an argon gas source (not shown). While rotating the holder 341 at, for example, 4 rpm, the surface of the base material 1 is irradiated with an argon ion beam generated from argon gas by the gridless ion beam generator 40 toward the base material 1 for, for example, 20 minutes. Impurities and oxides are removed and cleaned. At this time, argon does not remain on the base material 1.

The cleaning of the base material 1 and the carbon target 312 is completed by the above steps S1 to S4. If the base material 1 and the carbon target 312 are properly cleaned, the procedure is not necessarily limited to the above procedure.

Next, the CNx film 2 is formed on the base material 1 while rotating the holder 341 in the vacuum chamber 34 at, for example, 4 rpm (step S5).
At this time, while rotating the holder 341 at, for example, 4 rpm, the nitrogen ion beam generated from the nitrogen gas introduced into the gridless ion beam generator 40 and the FCVA film forming apparatus 30 deflect the holder 341 with respect to the path of the droplet. By supplying both of the fine carbon particles to the base material 1 for, for example, 20 minutes, a CNx film 2 having a thickness of about 0.5 μm is applied to the base material 1.
In order to suppress the temperature rise of the base material 1, the irradiation of the nitrogen ion beam and the supply of carbon particles may be performed intermittently with a rest time of about 10 seconds as the time for dissipating heat from the base material 1.

After the film formation is completed, the base material 1 is cooled in the vacuum chamber 34. Then, the base material 1 is taken out from the manufacturing apparatus 3 (step S6).

The table below shows an example of the film formation conditions for the CNx film 2.

By the film formation step of the CNx film 2 described above, a dense CNx film 2 containing nitrogen is uniformly formed on the surface of the base material 1. Through such a film forming step, the sliding member 10 provided with the base material 1 coated with the CNx film 2 is manufactured. The CNx film 2 formed on the substrate 1 has a nitrogen content of 12 to 20 atomic% as described above, and has the hardness and Young's modulus described above.

(Changes in surface condition of CNx film due to use in refrigerant atmosphere)
The CNx film 2 formed on the base material 1 of the sliding member 10 slides on the surface of the mating member of the sliding member 10, so that the state of the surface changes.
Here, when the sliding member 10 is used in a refrigerant atmosphere, the surface layer of the CNx film 2 changes to a graphite-like structure with the release of nitrogen from the CNx film 2, or instead of that. At the same time, the hydrogen contained in the refrigerant and the carbon of the CNx film 2 are bonded to form a polymer-like carbon on the surface layer of the CNx film 2. This is confirmed by the results of surface analysis by reflection spectroscopy, as shown in FIGS. 12 and 13.

Here, in the reflection spectroscopy method, the absolute reflectance spectrum when a test piece coated with a thin film is irradiated with light of a predetermined wavelength is measured, and the measured value of the absolute reflectance spectrum and the multiplexing of the incident light are multiplexed. This is a method of measuring the thickness and optical constant of a thin film by fitting it with the absolute reflectance spectrum calculated from an optical model that takes reflection into consideration.
The absolute reflectance R in this method is expressed by the following equation (1). Absolute reflectance R depends on the wavelength of light.

I _i : Incident light intensity per unit time
I _r: reflected light intensity per unit time

Calculate the absolute reflectance from the optical model. The absolute reflectance R when light is incident on a single-layer thin film in air at an incident angle θ _{0 is shown below.}

d ₁ : Thin film thickness λ: Light wavelength n: Refractive index k: Extinction coefficient θ ₀ : Light incident angle θ ₁ : Transmission angle to thin film θ ₂ : Transmission angle to substrate 0,1, The materials shown in 2 are air, thin film, and base material, respectively.

It is known that the surface states of various carbon films such as ta-C and a-C are represented by the extinction coefficient k and the refractive index n as shown in FIG. The smaller the refractive index n, the softer it becomes. "Graphite film" corresponds to a layered graphite-like surface state, and "Polymer Like Carbon" corresponds to a polymer-like surface state softened by the bond of hydrogen and carbon. These Graphite film and Polymer Like Carbon are softer than other carbon films such as ta-C. In addition, "a-C: H" in FIG. 14 means a carbon film containing or bonded to hydrogen.

In FIG. 12, the data of various carbon films shown in FIG. 14 are plotted according to the legend from the analysis by reflection spectroscopy using light having a wavelength of 550 nm, and also from the analysis by reflection spectroscopy, the partner in the refrigerant atmosphere. The data of the CNx film 2 that has not been subjected to friction with the member is plotted by white circles (○), and the data of the CNx film 2 after being subjected to friction in a refrigerant atmosphere under dry conditions is black. It is plotted by a circle (●). In FIG. 12, the horizontal axis is the refractive index n, and the vertical axis is the extinction coefficient k.

The corresponding white circle plots A1, A2, A3 and A4 before friction are surrounded by a circle A, and the corresponding black circle plots B2 and B3 after friction are surrounded by a circle B. Plots B2 and B3 correspond to Examples 2 and 3 (FIG. 15) described later, respectively.
From FIG. 12, when the sliding member 10 slides with the mating member in a refrigerant atmosphere, the surface state of the CNx film 2 changes from the range surrounded by the circle A to the range surrounded by the circle B. You can see that. Since the range of the circle B corresponds to the Polymer Like Carbon shown in FIG. 14, it is considered that the surface layer of the CNx film 2 is changed to a polymer-like carbon (tribofilm) by friction in a refrigerant atmosphere.

Further, in FIG. 13, the data of the CNx film 2 after being subjected to friction under the refrigerant atmosphere under the boundary lubrication condition from the analysis by reflection spectroscopy using light having a wavelength of 550 nm is shown by black circles (●). I'm plotting. Plots C1 to C3 correspond to Examples 7, 4 and 6 (FIG. 16) described later, respectively. Since plots C1 to C3 correspond to the Graphite film and Polymer Like Carbon shown in FIG. 14, the surface layer of the CNx film 2 has a graphite-like structure or a polymer-like carbon due to friction in a refrigerant atmosphere. It is probable that it changed to.

(Friction characteristics of CNx film in a refrigerant atmosphere)
Below, as a new finding, we disclose that the CNx film exhibits low friction in a refrigerant atmosphere.
The friction characteristics of the CNx film in a refrigerant gas atmosphere will be mainly described with reference to FIGS. 15 and 16 showing the measurement results by the ring-on-disk friction and wear test.
Example 1 shown in FIG. 15 shows the friction coefficient of the CNx film 2 under a nitrogen gas atmosphere (under a non-refrigerant atmosphere) under dry conditions where no lubricating oil is used.
Examples 2 and 3 show the coefficient of friction of the CNx film 2 under the R32 refrigerant gas atmosphere under dry conditions where no lubricating oil is used.
In each of Examples 1 to 3, the CNx film is formed by supplying carbon particles by the FCVA method while irradiating the base material 1 of SUSJ2 with a nitrogen ion beam using the gridless ion beam generator 40 as described above. It is the one with 2. Comparative Example 1 shows the coefficient of friction of the base material 1 of SUSJ2 to which the CNx film 2 is not applied under the atmosphere of R32 refrigerant gas.
The nitrogen gas flow rate during film formation of the CNx film 2 is 15 SCCM in Example 1 and 40 SCCM in Examples 2 and 3. 40 SCCM corresponds to a nitrogen content of 17.4 atomic%.
In both Examples 1 to 3 and Comparative Example 1, the pressure of the atmospheric gas was 0.3 MPa.
Since the friction coefficient of Comparative Example 1 is 0.34, while the friction coefficient of Examples 1 to 3 is about 0.02, according to Examples 1 to 3, the friction coefficient of Comparative Example 1 which is not coated is compared with that of Comparative Example 1. Friction can be sufficiently reduced even under boundary lubrication.

Next, both Examples 4 to 7 and Comparative Example 2 shown in FIG. 16 show the friction coefficient in a refrigerant gas atmosphere and under boundary lubrication conditions (a state in which the refrigerant is dissolved in the lubricating oil).
In each of Examples 4 to 7, the base material 1 of SUJ2 is irradiated with a nitrogen ion beam using the gridless ion beam generator 40 as described above, and carbon particles are supplied by the FCVA method to supply a CNx film. It is the one with 2. “N increase” in Example 5 means that the same base material 1 was irradiated with a nitrogen ion beam and carbon particles were supplied twice in succession under the same conditions as in Example 4. .. In Example 4 and the like without the description of "N increase", it was carried out only once. In Example 6 only, a graphite layer is further applied on the CNx film 2. This graphite layer is formed on the CNx film 2 by the FCVA film forming apparatus 30 in a state where the introduction of nitrogen gas into the gridless ion beam generator 40 is stopped following the film formation of the CNx film 2 on the base material 1. Is given to. The film thickness of this graphite layer is about 100 nm, and the film thickness of the CNx film 2 is about 300 nm. The graphite layer is soft, and when the CNx film 2 is coated with the graphite layer, a soft structural change layer 2A is formed on the CNx film 2 after sliding (lower side of FIG. 1). A composite layer is formed on the base material 1. Therefore, Example 6 shows a sufficiently low coefficient of friction. The film thickness of the graphite layer of Example 6 is set to be the same as the thickness of the polymer-like carbon layer that appears on the surface layer of the CNx film 2 due to sliding in the refrigerant gas atmosphere.
Comparative Example 2 shows the friction coefficient of the base material 1 of SUSJ2 to which the CNx film 2 is not applied.
Only Example 7 shows the coefficient of friction under the atmosphere of R1234yf refrigerant, which is an HFO refrigerant, and the other Examples 4 to 6 and Comparative Example 2 show the coefficient of friction under the atmosphere of R32 refrigerant gas. A PAG (polyalkylene glycol) -based lubricating oil is used in Example 7, and a POE-based lubricating oil is used in the other Examples 4 to 6 and Comparative Example 2 according to the refrigerant used.
The nitrogen gas flow rate during film formation of the CNx film 2 is 40 SCCM in both Examples 4 to 7 and Comparative Example 2.
In both Examples 4 to 6 and Comparative Example 2, the pressure of the atmospheric gas is 1 MPa, and the pressure of the atmospheric gas in Example 7 is 0.2 MPa.
While the friction coefficient of Comparative Example 2 is 0.10, the friction coefficient of Examples 4 to 7 is about 0.03 to 0.07. According to Examples 4 to 7, friction can be sufficiently reduced as compared with Comparative Example 2 in which the coating is not applied.

From the above, by using the gridless ion beam generator 40, it is possible to realize the CNx film 2 in which the nitrogen content is increased to 14 to 20 atomic%, and the CNx film 2 is applied to the base material 1. According to this, the friction can be sufficiently reduced from the results shown in FIGS. 3, 15, 16 and the like. By reducing friction, high efficiency and energy saving are realized by reducing the loss of sliding parts.
In addition, as shown in FIG. 4, since the Young's modulus of the CNx film 2 is 160 to 250 GPa, the Young's modulus equivalent to the Young's modulus of the metal material typically used for the base material (around 200 GPa) is obtained. It will be given to the CNx membrane. Therefore, it is possible to prevent the CNx film 2 from cracking and the CNx film 2 from peeling off from the base material 1, and improve the reliability of the sliding member 10 and the device including the sliding member 10.

List the Young's modulus of major mechanical materials.
Industrial Pure Iron 205 GPa
Rolled steel (SS400) 206 GPa
Medium carbon steel (S45C) 205 GPa
High-strength steel (HT80) 203 GPa
Stainless steel (SUS631) 204 GPa
Copper 125 GPa

(Application example)
The CNx film 2 described above is preferably applied to a sliding member constituting a compressor that compresses a refrigerant. The compressor and the sliding members provided in the compressor are illustrated below.
17 and 18 show a compressor 5 provided with a scroll compression mechanism 50. The compressor 5 compresses an HFC-based or HFO-based refrigerant, or a refrigerant containing hydrogen such as ammonia, by the scroll compression mechanism 50.
The compressor 5 transmits rotational driving force to the scroll compression mechanism 50, the thrust bearing 51 that receives the thrust load from the scroll compression mechanism 50, the thrust plate 58 as a thrust member, and the scroll compression mechanism 50, and the bearings 521 and 521. It includes a shaft 53 rotatably supported by 522, a motor 54 that outputs torque to the shaft 53, and a housing 55.
The refrigerant gas introduced into the housing 55 through the introduction pipe 56 is sucked into the scroll compression mechanism 50, compressed, and discharged to the outside from the discharge pipe 57.
Members arranged inside the housing 55, such as the scroll compression mechanism 50, the thrust bearing 51, and the thrust plate 58, are arranged in a refrigerant atmosphere.

The scroll compression mechanism 50 includes a fixed scroll 501 fixed to the housing 55, a swivel scroll 502 that revolves around the fixed scroll 501, and an Oldham link 504. The swivel scroll 502 is connected to an eccentric portion 531 provided on one end side 53A of the shaft 53. As the swivel scroll 502 turns, the side surface of the lap 501B rising from the end plate 501A of the fixed scroll 501 and the side surface of the lap 502B rising from the end plate 502A of the swivel scroll 502 slide.
The thrust bearing 51 receives a thrust load from the scroll compression mechanism 50 at one end side 53A of the shaft 53, and the thrust plate 58 receives a thrust load from the other end 53B of the shaft 53. FIG. 19 FIG. 19 The end plate 502A of the swivel scroll 502 slides on the thrust bearing 51.

The Oldham link 504 (FIGS. 17 and 20) engages the thrust bearing 51 and the swivel scroll 502 to regulate the rotation of the swivel scroll 502. The first keys 504A and 504A provided on the Oldham link 504 slide on the inner wall of a key groove (not shown) provided on the upper surface of the thrust bearing 51. The second keys 504B and 504B provided on the Oldham link 504 slide on the inner wall of a key groove (not shown) provided on the end plate 502A of the swivel scroll 502.

The CNx film 2 is applied to at least one of the above sliding members, that is, the thrust bearing 51, the thrust plate 58, the lap 501B of the fixed scroll 501, the lap 502B of the swivel scroll 502, and the Oldham link 504. As described above, friction can be sufficiently reduced even under dry conditions and boundary lubrication conditions.
It is sufficient that the CNx film 2 is applied to at least the region sliding with the mating member in each of the thrust bearing 51, the thrust plate 58, the lap 501B of the fixed scroll 501, the lap 502B of the swivel scroll 502, and the Oldham link 504. .. For example, in FIG. 18 of the thrust plate 58, the CNx film 2 may be applied only to one surface 58A that slides on the other end 53B of the shaft 53.

The CNx film 2 can also be applied to sliding members other than the thrust bearing 51, the thrust plate 58, the laps 501B and 502B, and the Oldham link 504 described above.
For example, it is arranged between the sliding surface of the bearings 521 and 522 that receives the radial load of the shaft 53, the outer peripheral portion of the eccentric portion 531 of the shaft 53 that supports the swivel scroll 502, and the inner peripheral portion of the boss 502C of the swivel scroll 502. It is also preferable to apply the CNx film 2 to the sliding surface of the drive bearing 505.

FIG. 21 shows a compressor 6 provided with a rotary compression mechanism 60. The compressor 6 compresses the refrigerant containing hydrogen by the rotary compression mechanism 60.
The compressor 6 transmits rotational driving force to the rotary compression mechanism 60, thrust bearings 63 and 64 that receive the thrust load from the rotary compression mechanism 60, and the rotary compression mechanism 60, and is rotatably supported by the thrust bearings 63 and 64. The shaft 65, a motor 66 that outputs torque to the shaft 65, and a housing 67 are provided.
Members arranged inside the housing 67, such as the rotary compression mechanism 60 and the thrust bearings 63 and 64, are arranged in a refrigerant atmosphere.

The rotary compression mechanism 60 includes a first compression mechanism 61 and a second compression mechanism 62. As shown in FIG. 22, the first compression mechanism 61 includes a cylinder 601, a piston rotor 602 that is rotated inside the cylinder 601 and a blade 603 that partitions a space inside the cylinder 601. The blade 603 is provided in the cylinder 601 so as to be able to advance and retreat in the radial direction of the cylinder 601 and is pressurized from the outside to the inside in the radial direction. The tip of the blade 603 slides on the outer peripheral portion of the rotating piston rotor 602.

The second compression mechanism 62 also includes a cylinder 601, a piston rotor 602, and a blade 603. The inside of the cylinder 601 of the first compression mechanism 61 is partitioned by a thrust bearing 63 and a partition wall 68. The inside of the cylinder 601 of the second compression mechanism 62 is partitioned by a thrust bearing 64 and a partition wall 68.

The refrigerant gas introduced from the accumulator 69 into the cylinders 601 of the first compression mechanism 61 and the second compression mechanism 62 is compressed in each cylinder 601 with the rotation of the piston rotor 602 coupled to the shaft 65, and the first The gas is discharged from the discharge ports 604 of the compression mechanism 61 and the second compression mechanism 62 into the housing 67, passes through the motor 66, and is discharged to the outside from the discharge pipe 605.

As described above, the CNx film 2 is applied to at least one of the blade 603 as a sliding member, the thrust bearings 63 and 64, the partition wall 68, the piston rotor 602, and the cylinder 601 to obtain dry conditions and boundary lubrication conditions. Even if it is, the friction can be sufficiently reduced.
It suffices that the CNx film 2 is applied to at least a region of the sliding member that slides with the mating member. For example, in the blade 603 (FIG. 22), the CNx film 2 may be applied only to the tip portion 603A that slides on the piston rotor 602. In the piston rotor 602, the CNx film 2 may be applied only to the outer peripheral portion that slides on the inner wall of the cylinder 601.

In addition, it is also preferable to apply the CNx film 2 to the sliding surface or the like of the thrust bearings 63 and 64 that receives the radial load of the shaft 65.

In addition to the above, the configurations listed in the above embodiments can be selected or appropriately changed to other configurations as long as the gist of the present invention is not deviated.
For example, instead of irradiating the argon ion beam, the substrate 1 is irradiated with an ion beam generated from an inert gas other than argon gas, such as a nitrogen ion beam generated from nitrogen gas. The surface of the gas may be cleaned.

Further, one or more intermediate layers for improving the adhesion of the CNx film 2 to the base material 1 may be provided between the base material 1 and the CNx film 2. The intermediate layer can be formed by using, for example, titanium, chromium, silicon, chromium nitride, titanium nitride, or the like.

Further, the CNx film 2 may include a plurality of layers having different hardness. Similarly, the CNx film 2 may contain a plurality of layers having different nitrogen contents.

1 Base material 1A Surface 2 Nitrogen-containing amorphous carbon film (CNx film)
2A Structural change layer 2B Hard layer 3 Manufacturing equipment 5, 6 Compressor 10 Sliding member 30 FCVA deposition equipment 31 Vacuum arc discharge generator 32 Filter unit 33 Droplet collection unit 34 Vacuum chamber 40 Gridless ion beam generator 41 Anode 42, 42A, 42B Cathode 43 Permanent magnet 44 Chamber 45 Outlet 50 Scroll compression mechanism 51 Thrust bearing 53 Shaft 53A One end 53B One end 54 Motor 55 Housing 56 Introduction pipe 57 Discharge pipe 58 Thrust plate (thrust member)
58A One side 60 Rotary compression mechanism 61 First compression mechanism 62 Second compression mechanism 63, 64 Thrust bearing 65 Shaft 66 Motor 67 Housing 68 Partition 69 Accumulator 70 Grid type ion beam generator 71 Microwave source 72 Discharge tube 73 Ignite 74 Grid 311 Trigger 312 Carbon target 321 Solenoid coil 322 Duct 341 Holder 501 Fixed scroll (1st scroll)
501A end plate 501B lap 502 swivel scroll (second scroll)
502A End plate 502B Wrap 502C Boss 504 Oldham link 504A, 504B Key 521,522 Bearing 505 Drive bearing 531 Eccentric part 601 Cylinder 602 Piston rotor 603 Blade 603A Tip part 604 Discharge port 605 Discharge pipe T Thickness

Claims (14)

An amorphous nitrogen-containing carbon film that is applied to the substrate and contains nitrogen.
The nitrogen content in the carbon film is 12 to 20 atomic%.
The Young's modulus of the carbon film is 160-250 GPa.
Nitrogen-containing carbon film. The hardness of the carbon film is 18 to 25 GPa,
The nitrogen-containing carbon film according to claim 1. A method of producing an amorphous carbon film containing nitrogen, which is applied to a base material.
While irradiating the base material with a nitrogen ion beam using a gridless ion beam generator, carbon is vapor-deposited on the base material by a filtered Casodic vacuum arc method.
A method for producing a nitrogen-containing carbon film. By setting the flow rate of nitrogen gas introduced into the gridless ion beam generator,
To give the carbon film a nitrogen content of 12 to 20 atomic%,
The method for producing a nitrogen-containing carbon film according to claim 3. Before forming the carbon film on the substrate,
The substrate is irradiated with an ion beam generated from the inert gas.
The method for producing a nitrogen-containing carbon film according to claim 3 or 4. A compressor that compresses a refrigerant containing hydrogen.
It has a sliding member with a nitrogen-containing amorphous carbon film applied to the base material.
The sliding member is arranged in an atmosphere in which the refrigerant is present.
The nitrogen content in the carbon film is 12 to 20 atomic%.
Compressor. A scroll compression mechanism including a first scroll and a second scroll that revolves with respect to the first scroll.
A shaft connected to the second scroll and rotatably supported,
A thrust bearing that receives a thrust load from the scroll compression mechanism on one end side of the shaft, and a thrust bearing.
A thrust member that receives a thrust load from the other end of the shaft is provided.
The sliding member
With the thrust bearing
With the thrust member
An Oldham link that engages with the thrust bearing and the second scroll to regulate the rotation of the second scroll.
With the lap of the first scroll
Corresponds to at least one of the laps of the second scroll.
The compressor according to claim 6. A cylinder, a piston rotor that rotates inside the cylinder, a rotary compression mechanism that includes blades that partition the space inside the cylinder, and
A thrust bearing that receives a thrust load from the rotary compression mechanism is provided.
The sliding member
Corresponding to at least one of the thrust bearing and the blade.
The compressor according to claim 6. A sliding member that constitutes a compressor that compresses a refrigerant containing hydrogen.
Arranged in an atmosphere where the refrigerant is present
An amorphous carbon film containing nitrogen is applied to the base material,
The nitrogen content in the carbon film is 12 to 20 atomic%.
Sliding member. The sliding member
A thrust bearing that receives a thrust load from the scroll compression mechanism provided in the compressor.
The sliding member according to claim 9. The sliding member
An Oldham link used in the scroll compression mechanism provided in the compressor.
The sliding member according to claim 9. The sliding member
A blade that constitutes a rotary compression mechanism provided in the compressor.
The sliding member according to claim 9. A sliding member used in an atmosphere where a refrigerant is present.
An amorphous carbon film containing nitrogen is applied to the base material,
The nitrogen content in the carbon film is 12 to 20 atomic%.
Sliding member. A method for manufacturing a sliding member that includes a base material having an amorphous carbon film containing nitrogen and is used in an atmosphere in which a refrigerant is present.
A gridless ion beam generator is used to irradiate the substrate with a nitrogen ion beam while depositing carbon on the substrate by a filtered Casodic vacuum arc method.
Manufacturing method of sliding member.

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