WO2016121936A1 - Amorphous hydrocarbon film, and sliding member and sliding system provided with said film - Google Patents

Abstract

According to the present invention, a low-friction coating 5 includes: an aliphatic hydrocarbon group that exhibits a peak in a region of 2900-3000 cm^-1 in an infrared absorption spectrum; a carbonyl group that exhibits a peak in a region of 1650-1800 cm^-1 in an infrared absorption spectrum; an aromatic component (C₇H₇ ⁺) that exhibits a peak at mass 91.1 in a positive ion spectrum obtained by TOF-SIMS; and a fused ring component (C₉H₇ ⁺) that exhibits a peak at mass 115.2 in a positive ion spectrum obtained by TOF-SIMS.

Description

Amorphous hydrocarbon film, sliding member and sliding system provided with the same

The present invention relates to an amorphous hydrocarbon film having lubricity, and a sliding member and a sliding system including the same.

In order to reduce the friction of the sliding system, it has been proposed to arrange a solid lubricating film on the sliding surface of the sliding member. As such a solid lubricating film, for example, a DLC (Diamond 膜 Like Carbon) film is known, and the following Patent Document 1 includes an oxygen-containing organic compound or an aliphatic amine compound on the sliding surface including the DLC film. A low friction sliding mechanism for supplying a low friction agent composition is described.

Also, Patent Document 2 below describes a low friction lubrication assembly including a first member having a first sliding surface and a second member having a second sliding surface. The first sliding surface has a chemical affinity with the OH group. The second sliding surface has an OH terminal sliding surface. By supplying an oxygen-containing compound (liquid lubricant) between the first and second sliding surfaces, a tribofilm terminated with hydrogen is formed between the first and second sliding surfaces. .

Japanese Unexamined Patent Publication No. 2005-98495 Japanese Unexamined Patent Publication No. 2012-92351

In the low friction sliding mechanism described in Patent Document 1 and the low friction lubrication assembly described in Patent Document 2, the friction coefficient of the sliding portion is reduced.
However, in Patent Document 1 and Patent Document 2, sliding is performed in a state where the liquid lubricant is supplied onto the sliding surface (fluid lubrication). That is, Patent Document 1 and Patent Document 2 cannot provide a reduction in friction under conditions in which a lubricant such as a liquid lubricant is not separately used (dry lubrication).

It is required to reduce the friction coefficient of the sliding surface (sliding portion) without using a lubricant separately. Furthermore, in order to further increase the efficiency of the sliding system, it is desired to further reduce the friction coefficient of the sliding surface.
Accordingly, an object of the present invention is to provide an amorphous hydrocarbon film that realizes a low friction coefficient.

Another object of the present invention is to provide a sliding member capable of reducing the friction coefficient of the sliding surface without using a lubricant separately.
Still another object of the present invention is to reduce the frictional force generated between the sliding surface and the sliding surface without using a separate lubricant, thereby greatly reducing the friction loss. It is to provide a sliding system that can.

The first aspect of the present invention is obtained by an aliphatic hydrocarbon group having a peak in the region of 2900 cm ⁻¹ to 3000 cm ⁻¹ in the infrared absorption spectrum and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Aromatic component (C ₇ H ₇ ⁺ ) having a peak at mass 91.1 in the positive ion spectrum, and a condensed ring having a peak at mass 115.2 in the positive ion spectrum obtained by time-of-flight secondary ion mass spectrometry Provided is an amorphous hydrocarbon film (5) containing at least one of system components (C ₉ H ₇ ⁺ ).

A second aspect of the present invention further comprises a carbonyl group which exhibits peaks in the region of 1650 cm ^-1 ~ 1800 cm ^-1 in an infrared absorption spectrum, it is amorphous hydrocarbon film according to the first aspect .
A third aspect of the present invention is the amorphous hydrocarbon film according to the first or second aspect, including both the aromatic component and the condensed ring system component.

A fourth aspect of the present invention is the amorphous hydrocarbon film according to any one of the first to third aspects, wherein the average thickness is 2 nm to 1000 nm.
A fifth aspect of the present invention is a sliding member (2) having a sliding surface (6) including a first coating (5) and formed using at least one of a metal and a ceramic, The first coating provides a sliding member including the amorphous hydrocarbon film (5) according to any one of the first to fourth aspects.

A sixth aspect of the present invention is the sliding member according to the fifth aspect, wherein the sliding member is formed using ZrO ₂ .
According to a seventh aspect of the present invention, there is provided a sliding member (2) according to the fifth or sixth aspect, wherein the sliding member (2) is in sliding contact with the sliding surface of the sliding member and comprises an amorphous carbon-based film. A sliding member (3) having a sliding surface (7) including two coatings (9), and the Young's modulus of the second coating is 200 GPa to 250 GPa. It is.

An eighth aspect of the present invention, the second coating is the outermost surface, containing a hydroxyl group exhibiting a peak in the region of 3000 cm ^-1 ~ 4000 cm ^-1 in an infrared absorption spectrum, according to the seventh aspect of the It is a sliding system.
In this section, numbers in parentheses indicate corresponding components in the embodiments described later, but this does not mean that the present invention should be limited to those embodiments. Absent.

According to the present invention, an aliphatic hydrocarbon group having a peak in the region of 2900 cm ⁻¹ to 3000 cm ⁻¹ in the infrared absorption spectrum and a mass of 91.1 in the positive ion spectrum obtained by time-of-flight secondary ion mass spectrometry. And an aromatic hydrocarbon component having at least one of a condensed ring component having a peak at a mass of 115.2 in a positive ion spectrum obtained by time-of-flight secondary ion mass spectrometry The film exhibits a low coefficient of friction. That is, it is possible to provide an amorphous hydrocarbon film that achieves a low coefficient of friction.

In addition, by providing the first film including the amorphous hydrocarbon film on the sliding surface of the sliding member formed using at least one of metal and ceramics, without using a lubricant separately, The friction coefficient of the sliding surface can be reduced.
Furthermore, the friction coefficient of the sliding surface can be reduced. As a result, the frictional force generated between the sliding surface and the sliding surface can be reduced without using a separate lubricant. Can be greatly reduced (friction torque can be reduced). Accordingly, the sliding system can be reduced in size and weight, and the reliability of the sliding system can be improved.

FIG. 1 is an enlarged cross-sectional view showing a main part of a sliding system according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing a configuration of a film manufacturing apparatus used for manufacturing a low friction coating included in the sliding member. 3A and 3B are cross-sectional views showing a sliding operation between the sliding member and the sliding member. FIG. 4 is a schematic cross-sectional view showing the configuration of the first friction tester. 5A and 5B are diagrams for explaining plate test pieces used in the first and second friction tests. FIG. 6 is a schematic cross-sectional view showing the configuration of the second friction tester. 7A and 7B are graphs showing a load and a friction coefficient in the first friction test. 8A and 8B are graphs showing the applied load and the friction coefficient in the second friction test. FIG. 9 is a diagram for explaining the upper layer of the plate test piece to be measured in the third and fourth friction tests. 10A and 10B are diagrams for explaining test conditions of the third and fourth friction tests. FIG. 11 is a graph showing the relationship between the applied load and the measured value of the friction coefficient in the third friction test. FIG. 12 is a graph showing the relationship between the applied load and the measured value of the friction coefficient in the fourth friction test. 13A and 13B are views showing the surface state of the outer surface (sliding region) of the pin test piece after the first friction test. 14A and 14B are views showing the surface state of the outer surface (sliding region) of the pin test piece after the second friction test. FIG. 15 is an image of an optical micrograph showing the outer surface (the sliding region) of the pin test piece after the third friction test. FIG. 16 is an image of an optical micrograph showing the outer surface (the sliding region) of the pin test piece after the fourth friction test. FIG. 17 is a graph showing infrared absorption spectra of the first and second sliding products by a microscopic transmission method. FIG. 18 is a graph showing infrared absorption spectra of the third and fourth sliding products by a microscopic transmission method. FIG. 19 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the first sliding product. FIG. 20 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the second sliding product. FIG. 21 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the third sliding product. FIG. 22 is a graph showing the secondary ion relative intensity ratio of C ₂ H ₅ ⁺ based on Zr ⁺ of the second sliding product. FIG. 23 is a graph showing the secondary ion relative intensity ratio of C ₉ H ₇ ⁺ based on Zr ⁺ of the second sliding product. FIG. 24 is a graph showing the secondary ion relative intensity ratio of C ₇ H ₇ ⁺ based on Zr ⁺ of the second sliding product. FIG. 25 is a graph showing a negative ion spectrum of the first sliding product obtained by TOF-SIMS. FIG. 26 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the second sliding product. FIG. 27 is a graph showing the secondary ion relative intensity ratio of C ₇ H ₅ O ₂ ^{− based on} the total negative ion intensity of the first and second sliding products. FIG. 28 is a graph showing an infrared absorption spectrum of the PLC film after the second friction test by a microscopic total reflection absorption (microscopic ATR) method (No. 1). FIG. 29 is a graph showing an infrared absorption spectrum of the PLC film after the second friction test by a microscopic ATR method (part 2). FIG. 30 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the PLC film (its sliding region) after the first friction test. FIG. 31 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the PLC film (non-sliding region thereof) after the first friction test. FIG. 32 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the PLC film (its sliding region) after the second friction test. FIG. 33 is a graph showing the positive ion spectrum obtained by TOF-SIMS of the PLC film (non-sliding region thereof) after the second friction test. FIG. 34 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the PLC film (its sliding region) after the first friction test. FIG. 35 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the PLC film (non-sliding region thereof) after the first friction test. FIG. 36 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the PLC film (its sliding region) after the second friction test. FIG. 37 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the PLC film (non-sliding region thereof) after the second friction test.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an enlarged cross-sectional view showing a main part of a sliding system 1 according to an embodiment of the present invention. The sliding system 1 includes a sliding member 2 and a sliding member 3 that is a counterpart material for the sliding member 2. The sliding member 2 is provided to be slidable relative to the sliding member 3. The sliding member 2 and the sliding member 3 may be ones that slide (move) only the sliding member 2 while the sliding member 3 is stationary, or the sliding member 2 is stationary. In this state, only the sliding member 3 may be slid (moved), or both the sliding member 2 and the sliding member 3 are moved to move the sliding member 3 to the sliding member 3. Alternatively, the sliding member 2 may be relatively slid.

The sliding member 2 includes a first substrate 4 having a surface (the lower surface in FIG. 1) and a low friction coating (amorphous hydrocarbon-based film, which covers at least a part of the surface of the first substrate 4. 1st coating) 5. The first substrate 4 is formed using oxide ceramics (ceramics) or metal. The oxide ceramic includes, for example, ZrO ₂ (more specifically, yttrium stabilized zirconia (YSZ)). ZrO ₂ may be heat-treated or may not be heat-treated. The metal includes, for example, at least one of palladium (Pd) or SUJ2 (high carbon chromium bearing steel). These oxide ceramics and metals have a catalytic property to dissociate and adsorb hydrogen molecules in a hydrogen atmosphere environment to generate active hydrogen (H ⁺ ).

The low friction coating 5 is an amorphous hydrocarbon film. The low friction coating 5 includes an aliphatic hydrocarbon group (for example, an alkyl group), a carbonyl group (—C (═O) —), an aromatic component (C ₇ H ₇ ⁺ ), and a condensed ring system component (C ₉ H ₇ ⁺ ). The aliphatic hydrocarbon group, a peak in the region of 2900 cm ^-1 ~ 3000 cm ^-1 in an infrared absorption spectrum (microscopic transmission method). Carbonyl group, a peak in the region of 1650 cm ^-1 ~ 1800 cm ^-1 in an infrared absorption spectrum (microscopic transmission method). The aromatic component (C ₇ H ₇ ⁺ ) shows a peak at a mass of 91.1 in a positive ion spectrum obtained by TOF-SIMS (time-of-flight secondary ion mass spectrometry). The condensed ring system component (C ₉ H ₇ ⁺ ) shows a peak at a mass of 115.2 in the positive ion spectrum obtained by TOF-SIMS. The low friction coating 5 functions as a sliding surface 6 that is in sliding contact with the sliding surface 7 of the sliding member 3.

The film thickness (average thickness) of the low friction coating 5 is 2 nm to 1000 nm. More preferably, it is 2 nm to 500 nm.
The sliding member 3 includes a second substrate 8 having a surface (upper surface in FIG. 1), and a PLC (Polymer-Like Carbon) film 9 covering at least a part of the surface of the second substrate 8. Including. The 2nd base material 8 is formed using steel materials, such as tool steel, carbon steel, stainless steel, chromium molybdenum steel, high carbon chromium bearing steel, for example.

The PLC film 9 is an amorphous carbon film and includes a short-chain polyacetylene molecule as a main component. The PLC film 9 is a film formed by an ionization vapor deposition method while applying a low bias voltage or a high bias voltage in an atmosphere environment of a hydrocarbon gas (for example, toluene (C ₇ H ₈ )). The Young's modulus of the PLC film 9 is 200 GPa to 250 GPa. The outermost surface of the PLC film 9 shows a peak in the region of 3000 cm ^-1 ~ 4000 cm ^-1 in an infrared absorption spectrum (microscopic transmission method). When an amorphous carbon-based film is manufactured while applying a high bias voltage, at least one of hydrogen and oxygen may be added to the amorphous carbon-based film. The PLC film 9 functions as a sliding surface 7 that is in sliding contact with the sliding surface 6 of the sliding member 2. The sliding surface 6 and the sliding surface 7 may be a flat plane as shown in FIG. 1, or may be a spherical surface or other curved surface.

A lubricant such as a liquid lubricant is not supplied to the sliding interface between the sliding surface 6 and the sliding surface 7 (that is, between the low friction coating 5 and the PLC film 9). That is, the sliding system 1 is slid under a non-lubricated condition.
Examples of the sliding system 1 include bearings, seals, flywheels, scissors, plunger pumps, artificial joints, and the like. Examples of the bearing include a roller bearing including a ball bearing and a tapered roller bearing, a bearing with a separator, and a sliding bearing.

When a ball bearing is adopted as the sliding system 1, the sliding surface 7 on which the PLC film 9 is disposed includes the inner surface of the cage, and the sliding surface 6 is made of oxide ceramics (ZrO ₂ or the like) or metal The outer surface of a ball made of (SUJ2, palladium, etc.) may be included. When an outer ring guide type ball bearing that guides the outer diameter of the cage on the inner circumference of the outer ring or an inner ring guide type ball bearing that guides the inner diameter of the cage on the outer circumference of the inner ring is used, the PLC film 9 Includes a guided surface of the cage, and the sliding surface 6 is made of oxide ceramics (such as ZrO ₂ ) or metal (SUJ2, palladium, etc.) that guides the cage. An annular guide surface may be included.

When a tapered roller bearing is employed as the sliding system 1, the sliding surface 7 on which the PLC film 9 is disposed may include the end surface of the collar, and the sliding surface 6 may include the outer peripheral surface of the roller. Further, the sliding surface 7 on which the PLC film 9 is disposed includes the outer peripheral surface of the roller, and the sliding surface 6 has an end surface of a collar made of oxide ceramics (ZrO ₂ or the like) or metal (SUJ2, palladium or the like). May be included.
When a bearing with a separator is adopted as the sliding system 1, the sliding surface 7 on which the PLC film 9 is disposed includes a separator, and the sliding surface 6 is made of oxide ceramics (ZrO ₂ or the like) or metal (SUJ2). , Palladium, etc.) may be included.

When a sliding bearing is employed as the sliding system 1, the sliding surface 7 on which the PLC film 9 is disposed includes the inner peripheral surface of the sliding bearing, and the sliding surface 6 is an oxide ceramic (ZrO ₂ or the like). Or an outer peripheral surface of a shaft made of metal (SUJ2, palladium, etc.).
When a seal is employed as the sliding system 1, the sliding surface 7 on which the PLC film 9 is disposed includes the outer peripheral surface of the shaft, and the sliding surface 6 is made of oxide ceramics (such as ZrO ₂ ) or metal ( SUJ2, palladium, etc.) may be included.

When scissors are used as the sliding system 1, the sliding surface 7 on which the PLC film 9 is disposed includes the blade surface of one blade, and the sliding surface 6 is made of oxide ceramics (ZrO ₂ or the like) The blade surface of the other blade made of metal (SUJ2, palladium, etc.) may be included.
When a plunger pump is employed as the sliding system 1, the sliding surface 7 on which the PLC film 9 is disposed includes the outer surface of the piston (plunger), and the sliding surface 6 is formed of oxide ceramics (ZrO ₂ or the like). ) Or metal (SUJ2, palladium, etc.) fixed swash plate may be included.

When an artificial joint is employed as the sliding system 1, the sliding surface 7 on which the PLC film 9 is disposed includes a contact surface on the receiving side, and the sliding surface 6 includes oxide ceramics (ZrO ₂ or the like) A bone-side contact surface made of metal (SUJ2, palladium, etc.) may be included.
In the above sliding system 1, the sliding surface 6 is provided on one member and the sliding surface 7 is provided on the other member, but the sliding surface 6 is provided on the other member and the sliding surface 7 is provided on one side. You may provide in this member.

FIG. 2 is a diagram schematically showing the configuration of the film manufacturing apparatus 11 used for manufacturing the low friction coating 5 included in the sliding member 2. The film manufacturing apparatus 11 includes a box-shaped chamber 12 having an internal space. The sliding member 2 and the sliding member 3 are accommodated in the internal space 10 of the chamber 12. The film manufacturing apparatus 11 further includes a holding table 13 provided in the internal space 10 of the chamber 12. In FIG. 2, the holding table 13 is a holding table for holding the sliding member 3, and is fixedly disposed in the internal space 10 of the chamber 12. The sliding member 3 carried into the internal space 10 of the chamber 12 is placed on the holding table 13 and held on the holding table 13. The sliding member 2 is placed on the sliding member 3.

The film manufacturing apparatus 11 drives (moves) the sliding member 2 in order to slide the sliding surface 6 of the sliding member 2 relative to the sliding surface 7 of the sliding member 3. 14 and a load applying mechanism 15 that applies a pressing load to the sliding member 3 of the sliding member 2 with respect to the sliding member 2. The drive mechanism 14 is a mechanism including a motor, for example. The film manufacturing apparatus 11 also includes a control device 16 that controls the operation of the apparatus provided in the film manufacturing apparatus 11 and the opening and closing of valves. The drive mechanism 14 includes, for example, a linear motion device using a combination of a motor and a ball screw. The load applying mechanism 15 includes, for example, a weight.

At the bottom of the chamber 12, an exhaust duct 17 for leading the gas in the internal space 10 of the chamber 12 is provided. Although FIG. 2 shows a configuration in which the exhaust duct 17 is provided at the bottom of the chamber 12, it may be provided at a position other than the bottom in the chamber 12.
In FIG. 2, the drive mechanism 14 and the load applying mechanism 15 are described as being provided. However, the load is applied between the sliding member 2 and the sliding member 3 and the sliding member 2 and the sliding target are provided. As long as the member 3 is configured to slide, the drive mechanism 14 and the load applying mechanism 15 do not need to be provided.

Further, a processing gas introduction pipe 19 is provided through the wall (for example, the side wall 18) of the chamber 12. The processing gas introduction pipe 19 is supplied with hydrogen gas pipe 20 to which hydrogen gas (H ₂ ) is supplied from a hydrogen gas supply source and alcohol as an example of a hydrocarbon-based substance from an alcohol container 37. The alcohol pipe 22, a water pipe 23 to which water is supplied from a water container 38, and a nitrogen gas pipe 33 to which nitrogen gas (N ₂ ) is supplied from a nitrogen gas supply source are connected. A hydrogen gas valve 24 for opening and closing the hydrogen gas pipe 20 and a hydrogen gas flow rate adjusting valve 25 for changing the opening degree of the hydrogen gas pipe 20 are interposed in the hydrogen gas pipe 20. The alcohol pipe 22 is provided with an alcohol valve 28 for opening and closing the alcohol pipe 22 and an alcohol flow rate adjusting valve 29 for changing the opening degree of the alcohol pipe 22. The water pipe 23 is provided with a water valve 30 for opening and closing the water pipe 23 and a water flow rate adjusting valve 31 for changing the opening degree of the water pipe 23. A nitrogen gas valve 34 for opening and closing the nitrogen gas pipe 33 and a nitrogen gas flow rate adjusting valve 35 for changing the opening degree of the nitrogen gas pipe 33 are interposed in the nitrogen gas pipe 33. In the alcohol container 37, the alcohol includes liquid alcohol, gaseous alcohol vaporized from the liquid alcohol, and carrier gas. The temperature of the alcohol container 37 is set to 20 ° C. ± 5 ° C. A gas alcohol supplied from the alcohol container 37 and a carrier gas supplied from the outside flow through the alcohol pipe 22. In the water container 38, the water includes liquid water and gaseous water vapor evaporated from the liquid water. The temperature of the water container 38 is set to 20 ° C. ± 5 ° C. In the water pipe 23, gaseous water vapor supplied from the water container 38 and carrier gas supplied from the outside flow.

The alcohol supplied to the processing gas introduction pipe 19 is methanol (methanol. CH ₃ OH), ethanol (ethanol. C ₂ H ₅ OH), 1-propanol (propan-1-ol. CH ₃ CH ₂ CH ₂ OH). And at least one of 2-propanol (propan-2-ol. CH ₃ CH (OH) CH ₃ ).
When the hydrogen gas valve 24 is opened in a state where the opening degree of the hydrogen gas pipe 20 is set to be large, a large flow rate of hydrogen from the hydrogen gas pipe 20 is supplied to the processing gas introduction pipe 19. At this time, when the alcohol valve 28 and / or the water valve 30 are opened, a small amount of alcohol gas and hydrogen gas (H ₂ ), which is a carrier gas supplied from the outside, and / or a small amount of water vapor and the outside are supplied from the outside. Hydrogen gas (H ₂ ), which is a carrier gas, is supplied into the processing gas introduction pipe 19 and sufficiently mixed (stirred) with a large flow of hydrogen gas (H ₂ ) in the process of flowing through the processing gas introduction pipe 19. Is done. By this mixing, special hydrogen gas (a gas containing hydrogen and alcohol (hydroxyl group-containing compound) and / or water (hydroxyl group-containing compound)) is generated. Alcohol and / or water are vaporized in the produced special hydrogen gas. The generated special hydrogen gas is introduced into the internal space 10 of the chamber 12 from the introduction port 32 formed at the tip of the processing gas introduction pipe 19. Thereby, the atmosphere of the internal space 10 becomes a special hydrogen gas atmosphere. The special hydrogen gas atmosphere does not contain oxygen.

Further, when the nitrogen gas valve 34 is opened in a state where the opening degree of the nitrogen gas pipe 33 is set to be large, a large flow of nitrogen from the nitrogen gas pipe 33 is supplied to the processing gas introduction pipe 19. At this time, when the alcohol valve 28 and / or the water valve 30 are opened, a small amount of alcohol gas and nitrogen gas (N ₂ ) which is a carrier gas supplied from the outside and / or a small amount of water vapor and the outside are supplied from the outside. Nitrogen gas (N ₂ ), which is a carrier gas, is supplied into the processing gas introduction pipe 19 and sufficiently mixed (stirred) with a large flow of nitrogen gas (N ₂ ) in the process of flowing through the processing gas introduction pipe 19 Is done. By this mixing, special nitrogen gas (gas containing nitrogen and alcohol (hydroxyl group-containing compound) and / or water (hydroxyl group-containing compound)) is generated. Alcohol and / or water is vaporized in the generated special nitrogen gas. The generated special nitrogen gas is introduced into the internal space 10 of the chamber 12. Thereby, the atmosphere of the internal space 10 becomes a special nitrogen gas atmosphere. The special nitrogen gas atmosphere does not contain oxygen.

Further, by opening the alcohol valve 28 and / or the water valve 30 in a state where the hydrogen gas valve 24 and the nitrogen gas valve 34 are opened, special nitrogen / hydrogen gas (nitrogen and hydrogen, alcohol (hydroxyl-containing compound) and / or Alternatively, water (a gas containing a hydroxyl group-containing compound) is generated. The generated special nitrogen / hydrogen gas is introduced into the internal space 10 of the chamber 12. Thereby, the atmosphere of the internal space 10 becomes a special nitrogen / hydrogen gas atmosphere. The special nitrogen / hydrogen gas atmosphere does not contain oxygen.

3A and 3B are cross-sectional views showing the sliding operation between the sliding member 2 and the sliding member 3. Hereinafter, a manufacturing example in which the low friction coating 5 is formed on the sliding surface 6 of the sliding member 2 using the film manufacturing apparatus 11 will be described with reference to FIG. 3A and 3B will be referred to as appropriate.
When the low friction coating 5 is manufactured (formed) using the film manufacturing apparatus 11, the sliding member 2 and the sliding member 3 are carried into the internal space 10 of the chamber 12. The loaded sliding member 3 is placed on the holding table 13 with the sliding surface 7 facing upward, and is held by the holding table 13. The loaded sliding member 2 is placed on the sliding member 3 with the sliding surface 6 facing downward. Note that the low friction coating 5 is not formed on the sliding surface 6 of the sliding member 2 at the time of loading. That is, the sliding surface 6 is made of oxide ceramics or metal.

After the sliding member 2 and the sliding member 3 are carried into the internal space 10 of the chamber 12, the control device 16 opens the hydrogen gas valve 24 and / or the nitrogen gas valve 34, and the alcohol valve 28 and / or the water valve 30. Then, the processing gas is supplied from the inlet 32 of the processing gas introduction pipe 19 to the internal space 10 of the chamber 12 (supply process). For example, it is assumed that the processing gas contains special hydrogen gas, and in this special hydrogen gas, a trace amount of gaseous alcohol and a trace amount of water vapor are respectively added to the hydrogen gas. This special hydrogen gas, in addition to hydrogen gas, is a liquid with respect to the sum of the flow rate of the carrier gas containing gaseous alcohol in the alcohol vessel 37 and the flow rate of the carrier gas containing gaseous water in the water vessel 38. The alcohol container 37 contains gaseous alcohol and gaseous water vapor in a volume ratio [alcohol / (alcohol + water)] of the flow rate of the carrier gas containing gaseous alcohol, for example, 4 to 44%.

The processing gas supplied into the chamber 12 spreads over the entire interior space 10 of the chamber 12. Thereby, the atmosphere (Air) in the internal space 10 of the chamber 12 is replaced with an atmosphere containing the processing gas. Note that the processing gas does not contain oxygen.
After the inner space 10 of the chamber 12 is filled with the atmosphere of the processing gas (in a state where the inner space 10 is the atmosphere of the processing gas), the control device 16 continues to supply the processing gas while the drive device 16 14, while applying a pressing load from the sliding surface 6 (sliding member 2) to the sliding surface 7 (sliding member 3), as shown in FIG. 7 starts sliding (sliding process) of the sliding surface 6 with respect to 7. With the application of the pressing load, the Hertz contact stress generated between the sliding surface 6 and the sliding surface 7 during sliding is 1.0 GPa or more. More preferably, the Hertz contact stress is 1.3 GPa to 2.4 GPa.

When a predetermined period (for example, 30 minutes) elapses from the start of sliding of the sliding surface 6, the alcohol valve 28 and the water valve 30 are closed, and the supply of alcohol and water to the internal space 10 is stopped.
As the sliding surface 6 slides with respect to the sliding surface 7, the sliding surface 6 slides with respect to the sliding surface 7 as a result of the catalytic action of the sliding surface 6 (ZrO ₂ or the like). Thus, the low friction coating 5 is formed. The low friction coating 5 exhibits a significantly low coefficient of friction of the order of 10 ⁻⁴ (less than 0.001). By providing the low friction coating 5 on the sliding surface 6 of the sliding member 2, a Friction-Fade-Out state (hereinafter referred to as “FFO”) having a friction coefficient of the order of 10 ⁻⁴ can be realized. In other words, as a result of the sliding of the sliding surface 6 with respect to the sliding surface 7, the friction coefficient gradually decreases with friction, and FFO can be expressed.

The low friction coating 5 is a transparent film having the same hardness as the PLC film 9 and showing interference fringes. Blisters (bubbles) are generated on the surface and inside of the low friction coating 5.
The inventors of the present application consider the following mechanism regarding the formation of such a low friction coating 5 (expression of FFO).
That is, as the sliding surface 6 slides (friction), the outermost surface of the PLC film 9 becomes wear powder due to friction and is transferred to the sliding surface 6. That is, a transfer film transferred from the PLC film 9 is formed on the sliding surface 6. As the sliding progresses, the PLC film 9 and the transfer film come to rub.

The metal (SUJ2, palladium, etc.) or oxide ceramics (ZrO ₂ ) constituting the sliding surface 6 has a catalytic property capable of generating active hydrogen by dissociating and adsorbing hydrogen molecules. Therefore, as a result of sliding the PLC film 9 on the sliding surface 6, active hydrogen comes to exist at the sliding interface due to the catalytic action of the sliding surface 6.
Alcohol contained in the atmosphere of the internal space 10 is hydrocracked by the acid catalyst action of active hydrogen on the sliding surface 6, and volatile gas is formed in the transfer film. And it is thought that the gas molecule layer of volatile gas is formed in the friction surface (sliding interface) of a transfer film. The thickness of this gas molecule layer is on the order of several molecules, and it is considered that FFO is expressed by gas lubrication at the monomolecular level of this volatile gas layer. That is, the low friction film 5 is formed based on the transfer film including the volatile gas layer.

In this embodiment, the supply of alcohol and water is stopped when a predetermined time has elapsed from the start of sliding of the sliding surface 6. Thereby, moisture (water) can be removed from the atmosphere of the internal space 10. By removing moisture (water) that can be a catalyst poison that weakens the catalytic action of oxide ceramics (ZrO ₂ ) or metal (SUJ, palladium), stabilization of these catalytic actions can be achieved.

When a predetermined period has elapsed from the start of sliding of the sliding surface 6, the control device 16 closes the opened valves (hydrogen gas valve 24, alcohol valve 28, water valve 30, nitrogen gas valve 34, etc.) and introduces processing gas. The introduction of the processing gas from the pipe 19 is stopped. Thereafter, the control device 16 carries out the sliding member 2 and the sliding member 3 from the internal space 10 of the chamber 12.

When methanol is employed as the alcohol, the flow rate of the carrier gas containing gaseous methanol in the alcohol container 37 and the carrier gas containing gaseous water vapor in the water container 38 with respect to gaseous methanol and gaseous water contained in the processing gas. The ratio of the flow rate of the carrier gas containing gaseous methanol in the alcohol container 37 is preferably 6% to 15%. Also, the carrier gas containing gaseous methanol in the alcohol container 37 with respect to the sum of the flow rate of the carrier gas containing gaseous methanol in the alcohol container 37 and the flow rate of the carrier gas containing gaseous water vapor in the water container 38. Even if the ratio of flow rates is other values (this value may include 100%), FFO can be expressed.

When ethanol is used as the alcohol, the flow rate of the carrier gas containing gaseous ethanol in the alcohol container 37 and the carrier gas containing gaseous water vapor in the water container 38 with respect to gaseous ethanol and gaseous water contained in the processing gas. The ratio of the flow rate of the carrier gas containing gaseous ethanol in the alcohol container 37 to the total of the flow rate of 6% to 30% is preferable. Also, the carrier gas containing gaseous ethanol in the alcohol container 37 with respect to the sum of the flow rate of the carrier gas containing gaseous ethanol in the alcohol container 37 and the flow rate of the carrier gas containing gaseous water vapor in the water container 38. Even if the ratio of flow rates is other values (this value may include 100%), FFO can be expressed. However, in particular, the carrier containing gaseous ethanol in the alcohol container 37 with respect to the sum of the flow rate of the carrier gas containing gaseous ethanol in the alcohol container 37 and the flow rate of the carrier gas containing gaseous water vapor in the water container 38. When the ratio of the gas flow rates is 15% to 25%, FFO can be expressed over a long period in a stable state.

Next, the first to fourth friction tests will be described.
FIG. 4 is a schematic cross-sectional view showing the configuration of the first friction tester 41. FIG. 5A is an enlarged cross-sectional view showing the surface of the plate test piece 42 to be measured in the first and second friction tests. FIG. 5B is a diagram showing the physical properties of the two-layer film 43 formed on the surface of the plate test piece 42 and the film production technique used in the first and second friction tests.

As the first friction tester 41, a pin-on-plate type reciprocating sliding friction tester shown in FIG. 4 was used. For the pin test piece 44 to be tested, a ZrO ₂ (YSZ) sphere having a diameter of 4.8 mm, which has been heat-treated in the atmosphere at 200 ° C. for 24 hours or treated in a hydrogen reducing atmosphere at 400 ° C. for 3 hours, is used. The load applied to the pin test piece 44 can be changed by placing the weight 71 above the pin test piece 44 to be tested and changing the weight of the weight 71.

The first friction tester 41 includes, for example, a cylindrical chamber 45, and a pin test piece 44 is accommodated in the chamber 45. The chamber 45 includes a bottomed cylindrical acrylic chamber body 46 and an acrylic lid 47 that closes the upper surface of the chamber body 46. The lid 47 is formed with an elongated opening 48 that is long in the sliding direction of the pin test piece 44, and the pin test piece 44 is disposed in the opening 48. A holding table 49 for holding the plate test piece 42 is disposed at the bottom of the chamber 45. A gas introduction pipe 51 is provided through the peripheral wall 50 of the chamber body 46. A first line 52 to which hydrogen gas is supplied and a second line 53 to which hydrogen gas containing gaseous alcohol and gaseous water vapor is supplied are connected to the gas introduction pipe 51. The first line 52 includes a first valve 54 for opening and closing the first line 52, a first flow rate adjusting valve 55 for adjusting the flow rate of hydrogen gas in the first line 52, A first flow meter 56 for detecting the flow rate of hydrogen gas in one line 52 is interposed. The second line 53 includes a second valve 57 for opening and closing the second line 53, a second flow rate adjusting valve 58 for adjusting the flow rate of hydrogen gas in the second line 53, A second flow meter 59 for detecting the flow rate of hydrogen gas in the second line 53 and an alcohol / water container 60 in which alcohol and water are stored are interposed. The temperature of the alcohol / water container 60 is set to 20 ° C. ± 5 ° C. In the alcohol / water container 60, the alcohol and water include a liquid alcohol, a liquid water solution, a gaseous alcohol vaporized from the solution, and a gaseous water vapor. By opening the second valve 57, hydrogen gas flows through the second line 53 and hydrogen gas is supplied to the alcohol / water container 60. As hydrogen gas flows through the alcohol / water container 60 in which alcohol and water are stored, gaseous alcohol and gaseous water vapor are carried to the hydrogen gas and reach the gas introduction pipe 51. Then, by opening the first valve 54 together with the opening of the second valve 57, hydrogen gas containing gaseous alcohol and gaseous water vapor is supplied into the chamber 45 through the gas introduction pipe 51. In the chamber 45, the atmosphere in the chamber 45 is provided so as to be controllable.

As the plate test piece 42, as shown in FIG. 5A, a silicon substrate 61 having a double-layer film 43 formed on the surface thereof was used. The double layer film 43 is a hard carbon film having a double layer structure. The lower layer side of the bilayer film 43 is a Si-DLC film 62. An upper layer side of the two-layer film 43 is a PLC (Polymer-Like-Carbon) film 63. The Si-DLC film 62 is obtained by performing an ionization vapor deposition method (PVD method) using a mixture of toluene and trimethylsilane (Si (CH ₃ ) ₄ ) at a gas flow ratio of 2: 3 as a raw material gas. Is formed. The PLC film 63 is formed by performing ionized vapor deposition while using only toluene as a source gas. The bias voltage at the time of PLC film formation was −0.4 kV (low bias voltage).

The processing pressure (deposition pressure, Pa) at the time of film formation of the Si-DLC film 62 and the PLC film 63, the bias voltage (Bias voltage, kV) at the time of film formation, the processing temperature (Heater temperature, K) at the time of film formation, Film thickness (nm), micro indentation hardness (GPa), Young's modulus (GPa), G-band peak position of Raman spectrum (G-peak position, cm ^-1 ), Raman spectrum Peak width at half maximum (FWHM (G), cm ^-1 ), peak intensity ratio of Raman spectrum D band to G band (I (D) / I (G)), estimated hydrogen content (at. %) Are shown in FIG. 5B, respectively.

FIG. 6 is a schematic cross-sectional view showing the configuration of the second friction tester 141. Parts common to the first friction tester 41 in the second friction tester 141 are denoted by the same reference numerals as those in FIG. That is, the configuration of the chamber 45 of the second friction tester 141 and the configuration of the pin test piece 44 and the like are the same as those of the first friction tester 41 unless otherwise specified. The difference between the second friction tester 141 and the first friction tester 41 is mainly in its air supply system.

A third line 101 to which nitrogen gas is supplied, and a fourth line 102 to which hydrogen gas as a carrier gas containing gaseous alcohol and gaseous water vapor is supplied to the gas introduction pipe 51 of the supply system And a fifth line 103 supplied with hydrogen gas as a carrier gas that does not contain gaseous water vapor that contains gaseous alcohol.
The third line 101 includes a third valve 105 for opening and closing the third line 101, a third flow rate adjusting valve 106 for adjusting the flow rate of nitrogen gas in the third line 101, A third flow meter 107 for detecting the flow rate of nitrogen gas in the third line 101 is interposed.

The fourth line 102 includes a fourth valve 108 for opening and closing the fourth line 102, a fourth flow rate adjusting valve 109 for adjusting the flow rate of hydrogen gas in the fourth line 102, The presence of gaseous alcohol and gaseous water vapor in which a fourth flow meter 110 for detecting the flow rate of hydrogen gas in line 4 and liquid alcohol (ethanol) and liquid water (distilled water) are stored An alcohol / water container 111 is interposed. The temperature of the alcohol / water container 111 is set to 20 ° C. ± 5 ° C. In the alcohol / water container 111, the alcohol and water include a liquid alcohol, a liquid water solution, a gaseous alcohol vaporized from the solution, and a gaseous water vapor. In the alcohol / water container 111, liquid ethanol and liquid water are mixed at a volume ratio of 3:10. “Ethanol + water” contained in the processing gas flowing through the fourth line 102 is a volume ratio of the volume of liquid ethanol alone before mixing = 3 and the volume of liquid water alone before mixing = 10. It contains gaseous ethanol vaporized from the solution being mixed and gaseous water vapor. Such a processing gas may hereinafter be referred to as “hydrogen gas containing ethanol generated from an ethanol volume concentration 23% aqueous solution (23% @)”. The alcohol / water container 111 may be mixed with liquid ethanol and liquid water in a volume ratio of 1: 4. “Ethanol + water” contained in the processing gas flowing through the fourth line 102 is a volume ratio of the volume of liquid ethanol alone before mixing = 1 to the volume of liquid water alone before mixing = 4. It contains gaseous ethanol vaporized from the solution being mixed and gaseous water vapor. Such a processing gas may be hereinafter referred to as “hydrogen gas containing ethanol generated from an ethanol volume 20% aqueous solution (20% @)”.

The fifth line 103 includes a fifth valve 112 for opening and closing the fifth line 103, a fifth flow rate adjusting valve 113 for adjusting the flow rate of hydrogen gas in the fifth line 103, 5, a fifth flow meter 114 for detecting the flow rate of hydrogen gas in the line 103, and an alcohol container 115 containing only liquid alcohol (ethanol) and containing gaseous alcohol are interposed. . Since the alcohol container 115 does not contain water except for water that cannot be removed from ethanol, the processing gas flowing through the fifth line 103 contains gaseous ethanol, but hardly contains water. Such a processing gas may be hereinafter referred to as “hydrogen gas containing ethanol generated from a 100% ethanol volume concentration liquid (100% @)”.

By switching the opening and closing of the third valve 105, the supply and stoppage of nitrogen as the main flow can be switched. Further, by opening at least one of the fourth and fifth valves 108 and 112, the component ratio of alcohol and water contained in the atmosphere in the chamber 45 can be controlled. In addition to the opening of these valves 108 and 112, by adjusting the opening degree of the flow rate adjusting valves 109 and 113, the component ratio of alcohol and water contained in the atmosphere in the chamber 45 can be controlled more finely.

The first and second friction tests will be described.
After the plate test piece 42 is set in the first friction tester 41 with the formation surface of the double-layer film 43 as a test surface, the friction speed is 8.0 mm / s, the friction stroke is 4.0 mm, and the supply gas to the chamber 45 Under the test conditions of a flow rate of about 2.0 to 2.5 (liters / minute) and no lubrication, the magnitude of the load applied to the surface of the plate test piece 42 through the pin test piece 44 is 19.6 N to 58.8 N. In the above range, the following first friction test and second friction test (maximum 28200 high load tests) were conducted while increasing stepwise in units of 1.96 N, and the occurrence of FFO was examined.
<First friction test>
In the first friction test, the supply of hydrogen gas (hydrogen gas containing alcohol and water) from the second line 53 is stopped. That is, only hydrogen gas was used as the supply gas to the chamber 45. The temperature in the chamber 45 was set to 20 ° C. ± 5 ° C., and the humidity in the chamber 45 was controlled at 0.1 to 0.3% RH. As shown by a broken line in FIG. 4, a bottomed container 72 made of polyethylene terephthalate (PET) is disposed at the bottom of the chamber 45, and a waste containing water is accommodated in the bottomed container 72. The bottomed container 72 is fixed to the bottom of the chamber 45 via a tape 73 (for example, a double-sided tape) in which an acrylic ester is applied as an adhesive to the adhesive surface. Therefore, the atmosphere in the chamber 45 contains ethanol obtained by hydrolysis of the acrylate ester.
<Second friction test>
The temperature in the chamber 45 was set to 20 ° C. ± 5 ° C. Hydrogen gas containing alcohol and water was used as a supply gas to the chamber 45. The mixing ratio of the alcohol is such that the volume% concentration of the liquid alcohol before mixing with respect to the total volume of the volume of liquid alcohol before mixing and the volume of liquid water before mixing is 6.3 to 1.7%.

FIG. 7A is a graph showing the load applied in the first friction test, and FIG. 7B is a graph showing the measured value of the friction coefficient in the first friction test.
In the first friction test, the value of the friction coefficient is relatively high (0.01 to 0.03) under the condition of a load of 19.6N to 25.5N. When the load was 27.4N, FFO (ultra low friction state) with a friction coefficient on the order of 10 ⁻⁴ was developed. The coefficient of friction at the time of FFO expression was less than 3 × 10 ⁻⁴ . However, after that, even if the load was increased, the FFO expression state was not stabilized, and the friction coefficient was repeatedly increased and decreased. FFO was expressed relatively stably under a load of 58.8N.

Such a FFO of less than 10 ⁻⁴ is considered to be a specific phenomenon in the absence of a liquid lubricant.
FIG. 8A is a graph showing the load applied in the second friction test, and FIG. 8B is a graph showing the measured value of the friction coefficient in the second friction test.
In the second friction test, FFO was expressed under a load load of 47.1 N or more. The friction coefficient at this time is about 0.0002. In the second friction test, there was a tendency that the FFO phenomenon was stably developed as compared with the first friction test. Further, in the second friction test, the friction coefficient tended to gradually decrease as the load was increased, which was slightly different from that in the first friction test.

Next, the third and fourth friction tests will be described. FIG. 9 is a view for explaining the upper layer of the plate test piece 42 to be measured in the third and fourth friction tests. FIG. 10 is a diagram for explaining the test conditions of the third and fourth friction tests.
The plate test piece 42 to be measured in the third and fourth friction tests includes a two-layer film 43 made of a hard carbon film having a two-layer structure (see FIG. 5A) on the surface layer side. In the third and fourth friction tests, the Si-DLC film constituting the lower layer of the two-layer film 43 has the same configuration as the Si-DLC film 62 (see FIG. 5A). A PLC (Polymer-Like-Carbon) film 163 constituting the upper layer (Surface layer) is partially different from the PLC film 63 (see FIG. 5A).

The main difference between the method for forming the PLC film 163 and the method for forming the PLC film 63 is that a high bias voltage (−4.0 kV) is employed as the bias voltage (Bias voltage) in the ionization deposition method (PVD method). is there. The PLC film 163 provided by such a method is a PLC film (high bias film formation PLC) containing a relatively large amount of graphite component as compared with the PLC film 63. In this embodiment, hydrogen is also added to the film (hydrogen-added high bias film formation PLC).

After setting the plate test piece 42 to the second friction tester 141 with the formation surface of the double-layer film 43 as a test surface, the test conditions of a friction speed of 8.0 mm / s, a friction stroke of 4.0 mm, and no lubrication were obtained. The third friction test and the third friction test were performed while gradually increasing the load applied to the surface of the plate test piece 42 through the pin test piece 44 from 19.6 N to 63.7 N in increments of 1.96 N. 4 friction tests (up to 28200 high load tests) were conducted to examine the FFO expression.

FIG. 10 is a diagram for explaining the test conditions of the third and fourth friction tests.
In the third and fourth friction tests, regardless of whether the familiar environment (Run-in environment) from the start of the test until the FFO develops or the FFO environment (FFO environment) after the FFO is developed, Nitrogen gas was supplied at a large flow rate (5.0 slm) as a flow. The temperature in the chamber 45 was set to 20 ° C. ± 5 ° C.

In the familiar environment (Run-in environment) of the third friction test, hydrogen gas (23% @) containing ethanol generated from an aqueous solution having a volumetric ethanol concentration of 23% is used as a subflow in the chamber 45 at a medium flow rate (180 sccm). Hydrogen gas (100% @) containing ethanol generated from a 100% ethanol volume concentration liquid was supplied at a minute flow rate (5 sccm).

Also, in the FFO environment (FFO environment) that expresses the FFO of the third friction test, the ethanol concentration and moisture concentration in the atmosphere in the chamber 45 are controlled to be lower than the familiar environment (Run-in environment). In order to express FFO, a method of controlling the ethanol concentration and the water concentration low is effective. Specifically, as a sub-flow in the chamber 45, hydrogen gas (23% @) containing ethanol generated from an aqueous solution with 23% ethanol volume concentration is supplied at a small flow rate, and ethanol generated from a 100% ethanol volume concentration liquid is supplied. Containing hydrogen gas (100% @) was supplied at a minute flow rate. Specifically, the supply flow rate of hydrogen gas (23% @) containing ethanol generated from an aqueous solution having a volumetric ethanol concentration of 23% was set to 40 sccm at the start of supply and then reduced to 20 sccm. In addition, the supply flow rate of hydrogen gas containing ethanol (100% @) generated from a 100% ethanol volume concentration liquid was set to 5 sccm at the start of supply and then reduced to 1 sccm.

Further, in a familiar environment (Run-in environment) of the fourth friction test, hydrogen gas (20% @) containing ethanol generated from an aqueous ethanol solution having a volume concentration of 20% is flowed at a medium flow rate (180 sccm) as a subflow in the chamber 45. ).
Further, in the FFO environment (FFO environment) of the fourth friction test, hydrogen gas (20% @) containing ethanol generated from a 20% aqueous solution of ethanol volume concentration was supplied as a subflow into the chamber 45 at a small flow rate. Specifically, the supply flow rate of hydrogen gas (20% @) containing ethanol generated from an aqueous ethanol solution having a volumetric ethanol concentration of 20% was set to 40 sccm at the start of supply and then reduced to 30 sccm.

FIG. 11 is a graph showing the relationship between the load (Load) and the measured value of the friction coefficient (Friction coefficient) in the third friction test.
In the third friction test, as shown in FIG. 11, the load was increased stepwise to 63.7N, and after the load reached 63.7N, the load was kept at 63.7N. After the point of time when the supply flow rate of hydrogen gas containing ethanol (23% @) generated from an aqueous solution with 23% ethanol volume concentration was reduced from 60 sccm to 40 sccm (sliding frequency of about 4700 times), the friction coefficient suddenly decreased and FFO appeared. . Furthermore, after the time when the supply flow rate of hydrogen gas containing ethanol (23% @) generated from an aqueous solution with a 23% ethanol volume concentration is reduced to 30 sccm (sliding frequency of about 5300 times), the friction coefficient is 1 × 10 ⁻⁴ or less. Stable FFO was expressed. The value of the friction coefficient of 1 × 10 ⁻⁴ or less is the noise level (1 mN) of the friction force measurement system. Thereafter, the expression of FFO was maintained up to a predetermined time of about 9600 sliding times, and the expression time of FFO was about 49 minutes. In the third friction test, the supply flow rate of the hydrogen gas containing ethanol (23% @) generated from the 23% ethanol volume concentration aqueous solution is set to 30 sccm when the number of sliding times is 5300, and the number of sliding times is 9300 times. At each point of time, it was reduced to 20 sccm.

FIG. 12 is a graph showing the relationship between the load (Load) and the measured value of the coefficient of friction (Friction coefficient) in the fourth friction test.
In the fourth friction test, as shown in FIG. 12, the load was increased stepwise to 63.7N, and after the load reached 63.7N, the load was kept at 63.7N. After the time when the supply flow rate of hydrogen gas containing ethanol (20% @) generated from an aqueous solution with 20% ethanol volume concentration was reduced from 60 sccm to 40 sccm (sliding frequency of about 5200 times), the friction coefficient suddenly decreased and FFO appeared. . Further, the friction coefficient decreased after the time when the supply flow rate of the hydrogen gas (20% @) containing ethanol generated from the 20% ethanol volume concentration aqueous solution was reduced to 30 sccm (sliding frequency: about 5700 times). After the FFO expression was continued for about 10 minutes, the friction test was terminated. There were several momentary increases in the coefficient of friction during FFO development. The coefficient of friction during FFO development was determined by the supply of ethanol-containing hydrogen gas (20% @) generated from an aqueous ethanol solution with a volume concentration of 20%. After the time when the flow rate was lowered to 30 sccm (sliding frequency: about 5700 times), the flow rate was stable at 2 × 10 ⁻⁴ .
<Measurement of surface condition>
The surface condition of the outer surface of the pin test piece 44 after completion of the first to fourth friction tests was measured using a white light interference type shape measuring machine (zygo, New View 5022).

FIG. 13 is a view showing the surface state of the outer surface (sliding region) of the pin test piece 44 after the first friction test. FIG. 14 is a diagram showing the surface state of the outer surface (the sliding region) of the pin test piece 44 after the second friction test. 13A and 14A are optical micrograph images of the outer surface of the pin test piece 44, and FIG. 13B shows the surface of the outer surface of the pin test piece 44 when cut along line XIIIB-XIIIB in FIG. 13A. FIG. 14B shows the distribution of the height, and FIG. 14B shows the distribution of the surface height of the outer surface of the pin specimen 44 when cut along the cutting plane line XIVB-XIVB in FIG. 14A. FIG. 15 is an image of an optical micrograph showing the outer surface (sliding region) of the pin test piece 44 after the third friction test, and FIG. 16 is an illustration of the pin test piece after the fourth friction test. It is an image figure of the optical micrograph which shows an outer surface (the sliding area | region).

After the first and second friction tests, a transparent film-like product is attached (formed) to the circular sliding area (corresponding to the Hertz contact surface) of the outer surface of the pin test piece 44. Yes. The thickness of the product formed after the first friction test is several nm to about 150 nm, and the thickness of the product formed after the second friction test is about 10 nm to about 500 nm. These products can be scraped off from the surface with a spatula or the like, that is, they can be said to be softer than a hard carbon film such as DLC.

In the sliding state between the pin test piece 44 and the PLC film 63, such a film-like product is formed on the outer surface of the pin test piece 44, and the product slides on the PLC film 63. It is thought that FFO was expressed. That is, it is considered that FFO can be expressed by the presence of this product.
<Analysis of the first to fourth sliding products>
A product (hereinafter referred to as “first sliding product”) on the outer surface (sliding region) of the pin test piece 44 after the first friction test, and a pin test piece 44 after the second friction test. On the outer surface (sliding region) of the pin (hereinafter referred to as “second sliding product”) and on the outer surface (sliding region) of the pin specimen 44 after the third friction test. Infrared spectroscopic analysis was performed on the product (hereinafter referred to as “third sliding product”). The product collected on the diamond substrate with a metal probe from the outer surface (sliding region) of the pin test piece 44 was analyzed in a measuring region of about 20 μm square using the microscopic transmission method.

Time-of-flight secondary ion mass (TOF-SIMS) analysis was also performed on the first to third sliding products. Using TOF-SIMS 5 manufactured by Ion-Tof, 300 μm square rasters were accumulated 30 times at 256 × 256 pixels using Bi ⁺ (30 keV, 1.4 pA) as primary ions.
FIG. 17 is a graph showing infrared absorption spectra of the first and second sliding products by a microscopic transmission method. In FIG. 17, the infrared absorption spectrum of the first sliding product is shown in the upper part of the figure, and the infrared absorption spectrum of the second sliding product is shown in the lower part of the figure. In addition, the first sliding product has a small amount of collected product, and therefore there is a portion where the spectrum is unclear.

According to FIGS. 17 and 18, in any of the first to fourth sliding product, the peak is observed in the region in the vicinity of 2900 cm ^-1 - 3000 cm ^-1. This peak is a bond peak of “C—H” and is presumed to be derived from an aliphatic hydrocarbon group such as a methylene group (—CH ₃ ) or a methyl group (—CH ₂ —).
When focusing on the baseline from the region of 800 cm ⁻¹ to 2500 cm ⁻¹ , both the first and second sliding products tend to fall to the right with increasing wavelength. Such a baseline trend is believed to originate from the carbonaceous material. From the results of Raman analysis conducted separately, it is assumed that this carbonaceous material is derived from an amorphous carbon-based material (amorphous carbon).

In the second sliding product, a peak is observed in the region near 1720 cm ⁻¹ . This peak is a bond peak of “—C (═O) —” and is presumed to originate from a carbonyl group. Even in the first sliding product, the presence of a peak is recognized in the region near 1720 cm ⁻¹ . It is considered that the peak of the first sliding product is unclear due to the small amount of the first sliding product collected.

In both the first and second sliding products, a peak is recognized in the region near 1600 cm ⁻¹ . This peak is considered to be either a peak derived from a benzene ring or a peak derived from a lower carboxylate.
FIG. 18 is a graph showing infrared absorption spectra of the third and fourth sliding products by a microscopic transmission method. In FIG. 18, the infrared absorption spectrum of the third sliding product is shown in the upper part of the figure, and the infrared absorption spectrum of the fourth sliding product is shown in the lower part of the figure.

In the third and fourth sliding products, as in the first and second sliding products, the peak is observed in the region in the vicinity of 2900cm ^-1 ~ 3000cm ^-1. This peak is a bond peak of “C—H” and is presumed to be derived from an aliphatic hydrocarbon group such as a methylene group (—CH ₃ ) or a methyl group (—CH ₂ —).
Further, when focusing on the baseline from the region of 800 cm ⁻¹ to 2500 cm ⁻¹ , both the third and fourth sliding products tend to fall to the right with increasing wavelength. Such a baseline tendency is considered to be derived from a carbonaceous material (specifically, an amorphous carbon-based material (amorphous carbon)).

In FIG. 18, a peak is recognized in the region near 1720 cm ⁻¹ in both the third and fourth sliding products. This peak is presumed to be a bond peak of “—C (═O) —” which is considered to be derived from a carbonyl group. Note that the peak in the region near 1720 cm ⁻¹ in FIG. 18 is not as clear as in the case of the second sliding product shown in FIG.
In both the third and fourth sliding products, a peak is recognized in the region near 1600 cm ⁻¹ . This peak is considered to be either a peak derived from a benzene ring or a peak derived from water. Note that the peak in the vicinity of 1600 cm ⁻¹ in FIG. 18 is not as clear as in the case of the second sliding product shown in FIG.

That is, even when any of the PLC film 63 and the PLC film 163 manufactured under different conditions is used as the upper layer of the plate test piece 42, the main component of the friction atmosphere is a reducing hydrogen atmosphere (first Slidable formation having at least one of an aliphatic hydrocarbon group and a carbonyl group even in an inert nitrogen atmosphere (third friction test or fourth friction test). An object was formed on the pin test piece 44, and it was confirmed that FFO was expressed in this sliding product.

FIG. 19 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the first sliding product. FIG. 20 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the second sliding product. FIG. 21 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the third sliding product. FIG. 22 is a graph showing the secondary ion relative intensity ratio of C ₂ H ₅ ⁺ based on Zr ⁺ of the second sliding product. FIG. 23 is a graph showing the secondary ion relative intensity ratio of C ₉ H ₇ ⁺ based on Zr ⁺ of the second sliding product. FIG. 24 is a graph showing the secondary ion relative intensity ratio of C ₇ H ₇ ⁺ based on Zr ⁺ of the second sliding product.

In the positive ion spectra of the first and second sliding products, as shown in FIGS. 19 and 20, C ₂ H ₃ ⁺ , C ₂ H ₅ ⁺ (Mass: 29.06), C ₃ H ₇ ⁺ , C ₄ H ₇ ⁺ , C ₇ H ₇ ⁺ (Mass: 91.13), C ₉ H ₇ ⁺ (Mass: 115.15) and many other ions are detected. Among these, C ₇ H ₇ ⁺ is considered to be derived from an aromatic component, and C ₉ H ₇ ⁺ is considered to be derived from a condensed ring system component.

Further, in the positive ion spectrum of the third sliding product, as shown in FIG. 21, C ₂ H ₃ ⁺ , C ₂ H ₅ ⁺ (Mass: 29.06), C ₃ H ₇ ⁺ , C ₄ H Many ions such as ₇ ⁺ , C ₇ H ₇ ⁺ (Mass: 91.13), C ₉ H ₇ ⁺ (Mass: 115.15) are detected. Among these, C ₇ H ₇ ⁺ is considered to be derived from an aromatic component, and C ₉ H ₇ ⁺ is considered to be derived from a condensed ring system component.

That is, even when any of the PLC film 63 and the PLC film 163 manufactured under different conditions is used as the upper layer of the plate test piece 42, the main component of the friction atmosphere is a reducing hydrogen atmosphere (first And the second friction test) and an inert nitrogen atmosphere (the third friction test and the fourth friction test) peak in mass 91.1 in the positive ion spectrum obtained by TOF-SIMS. And a sliding product containing a condensed ring system component having a peak at a mass of 115.2 in the positive ion spectrum obtained by TOF-SIMS is formed, and FFO is expressed in this sliding product. I was able to confirm that.

Further, in order to quantitatively analyze C ₂ H ₅ ⁺ , C ₉ H ₇ ⁺ and C ₇ H ₇ ⁺ , each ion and the material of the pin test piece 44 are used for the first and second sliding products. The relative intensity ratio with Zr ⁺ ions derived from (ZnO ₂ ) was examined. 22 to 24, the first and second sliding products, which are products of the sliding region on the outer surface of the pin test piece 44, are the products of the non-sliding region on the outer surface of the pin test piece 44. It shows in comparison with.

From FIG. 22 to FIG. 24, all of C ₂ H ₅ ⁺ , C ₉ H ₇ ⁺ and C ₇ H ₇ ⁺ are generated in the sliding region more than the non-sliding region on the outer surface of the pin specimen 44. I know that.
FIG. 25 is a graph showing a negative ion spectrum of the first sliding product obtained by TOF-SIMS. FIG. 26 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the second sliding product. FIG. 27 is a graph showing the secondary ion relative intensity ratio of C ₇ H ₅ O ₂ ^{− based on} the total negative ion intensity of the first and second sliding products.

In the negative ion spectra of the first and second sliding products, as shown in FIG. 25 and FIG. 26, there are many C ₇ H ₅ O ₂ ⁻ (Mass: 121.12) of benzoate ions having a benzene ring. Has been detected. Further, it can be seen from FIG. 27 that more benzoate ions are generated in the sliding region than in the non-sliding region on the outer surface of the pin test piece 44.
Further, as described above with reference to FIG. 17, a peak was recognized in the region near 1600 cm ⁻¹ in both the first and second sliding products. By referring to the results of FIGS. 25 to 27 together, it can be seen that this peak is not a peak derived from a lower carboxylate but a peak derived from a benzene ring.

As will be described later, C ₇ H ₅ O ₂ ⁻ is also detected from the surface of the PLC film 63, and the PLC film 63 is considered to be a component due to transfer / degeneration.
<Analysis of the surface of the PLC film 63>
The surface of the PLC film 63 before and after the second friction test was analyzed by a micro total reflection absorption (micro ATR) method using a germanium prism.

Further, TOF-SIMS analysis was also performed on the surface of the PLC film 63 after the first and second friction tests. Using TOF-SIMS 5 manufactured by Ion-Tof, 300 μm square rasters were accumulated 30 times at 256 × 256 pixels using Bi ⁺ (30 keV, 1.4 pA) as primary ions.
The infrared absorption spectrum of the second sliding product is compared with the infrared absorption spectrum of the surface of the PLC film 63 before and after the second friction test. 28 and 29 are graphs showing infrared absorption spectra of the PLC film 63 before and after the second friction test by the microscopic ATR method. 28 and 29, the infrared absorption spectrum of the PLC film 63 after the second friction test is shown in the lower part of the figure, and the infrared of the PLC film 63 before the second friction test is shown in the middle part of the figure. An absorption spectrum is shown, and an infrared absorption spectrum of the surface of Si-DLC is shown in the upper part of the figure for reference.

According to FIG. 29, in an infrared absorption spectrum of the surface of the PLC film 63 after the second friction test, in the region of 1650 cm ^-1 ~ 1800 cm ^-1, around 1720 cm ^-1 of the second sliding product The peak derived from the carbonyl group (see FIG. 17, considered to be a peak derived from the carbonyl group) and the peak near 1600 cm ⁻¹ (see FIG. 17, considered to be the peak derived from the benzene ring) were observed. There wasn't. Further, also the spectrum of the surface of the PLC film 63 before the friction test shown in FIG. 29, the peak of the peak and 1600cm around ^-1 near 1720 cm ^-1 was observed. Peak peak and 1600cm around ^-1 from a second carbonyl group appearing in the region of 1650 cm ^-1 ~ 1800 cm ^-1 seen in the sliding product shown in FIG. 17, the front and rear of the second friction test Since it is not detected from any of the PLC films 63, the second sliding product is not a simple transfer of the PLC film 63, and is newly generated by a tribochemical reaction based on the transferred substances and the atmospheric gas. It is inferred that this is a compound produced in

Further, the surface of the PLC film 63 after the second friction test, focusing on the region in the vicinity of 3800 cm ^-1 ~ 3000 cm ^-1, the presence of a peak derived from the free O-H group (hydroxyl group), and O-H groups The presence of a peak derived from is recognized. The presence of free O—H groups on the outermost surface of the friction that cause molecules to move is thought to cause a decrease in shearing force when sliding against the surface of the other side of the friction, which is considered to be a cause of FFO expression. It is done. Free OH groups are not detected from the surface of Si-DLC shown as a reference in FIGS. 28 and 29, and it can be said that they are not present in common in the hard carbon film.

FIG. 30 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the PLC film 63 (sliding region thereof) after the first friction test. FIG. 31 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the PLC film 63 (non-sliding region thereof) after the first friction test. FIG. 32 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the PLC film 63 (sliding region thereof) after the second friction test. FIG. 33 is a graph showing a positive ion spectrum obtained by TOF-SIMS of the PLC film 63 (non-sliding region thereof) after the second friction test.

FIG. 34 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the PLC film 63 (sliding region thereof) after the first friction test. FIG. 35 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the PLC film 63 (non-sliding region thereof) after the first friction test. FIG. 36 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the PLC film 63 (sliding region thereof) after the second friction test. FIG. 37 is a graph showing a negative ion spectrum obtained by TOF-SIMS of the PLC film 63 (non-sliding region thereof) after the second friction test.

From the spectra shown in FIGS. 30 to 37, the aromatic component (C ₆ H ₅ ⁺ , C ₇ H ₇ ⁺ ), the condensed ring system component (C ₉ H ₇ ⁺ , C ₁₀ H ₈ ⁺ ) are formed on the surface of the PLC film 63. , C ₁₂ H ₈ ⁺ , C ₁₃ H ₉ ⁺ ), carbon-based components (C ₉ H ⁻ , C ₁₀ H ⁻ ), sulfur oxide-based components (SO ₂ ⁻ , SO ₃ ⁻ , HSO ₄ ⁻ ), silica ions ( The presence of Si ₂ O ₅ H ⁻ , Si ₃ O ₇ H ⁻ ) and benzoate ions (C ₇ H ₅ O ₂ ⁻ ) is observed. It is considered that the aromatic component, the condensed ring system component, and the carbon component are derived from the PLC film 63.

It was recognized that the aromatic component, the condensation component, the benzoate ion, and the sulfur oxide component tend to be more in the sliding region than in the non-sliding region on the surface of the PLC film 63. On the other hand, no clear difference was observed between the sliding area on the surface of the PLC film 63 and the non-sliding area.
According to this embodiment the above, the low friction coating 5 is an aliphatic hydrocarbon group which exhibits peaks in the region of 2900 cm ^-1 ~ 3000 cm ^-1 in an infrared absorption spectrum, 1650 cm ^-1 ~ 1800 cm in the infrared absorption spectrum ^-1 , a carbonyl group having a peak in the region, an aromatic component (C ₇ H ₇ ⁺ ) having a peak at a mass of 91.1 in a positive ion spectrum obtained by TOF-SIMS, and a positive ion obtained by TOF-SIMS And a condensed ring system component (C ₉ H ₇ ⁺ ) having a peak at a mass of 115.2 in the ion spectrum. The low friction coating 5 having such physical properties exhibits a remarkably low coefficient of friction of the order of 10 ⁻⁴ (less than 0.001). That is, it is possible to provide the low friction coating 5 that realizes a remarkably low coefficient of friction.

Further, the friction coefficient of the sliding surface 6 can be reduced without using a lubricant separately.
Further, the friction coefficient of the sliding surface 6 can be remarkably reduced. As a result, the frictional force generated between the sliding surface 6 and the sliding surface 7 can be reduced without using any lubricant. Thereby, the friction loss accompanying sliding of the sliding system 1 can be significantly reduced (friction torque can be greatly reduced). Therefore, the sliding system 1 can be reduced in size and weight, and the reliability of the sliding system 1 can be improved.

As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.
For example, in the above-described embodiment, the low friction coating 5 has been described as including a carbonyl group. However, the low friction coating may be configured so as not to include a carbonyl group.
In the above-described embodiment, the low friction coating 5 has been described as a configuration including both the aromatic component (C ₇ H ₇ ⁺ ) and the condensed ring system component (C ₉ H ₇ ⁺ ). 5 may be a structure containing at least one of an aromatic component (C ₇ H ₇ ⁺ ) and a condensed ring system component (C ₉ H ₇ ⁺ ).

Other various design changes can be made within the scope of the matters described in the claims.

This application is a Japanese patent application filed on January 29, 2015 (Japanese Patent Application No. 2015-015850), a Japanese patent application filed on January 29, 2015 (Japanese Patent Application No. 2015-015551), and an application filed on January 19, 2016. This is based on a Japanese patent application (Japanese Patent Application No. 2016-008236) and a Japanese patent application filed on January 19, 2016 (Japanese Patent Application No. 2016-008237), the contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 1 ... Sliding system, 2 ... Sliding member, 3 ... Sliding member, 5 ... Low friction coating (amorphous hydrocarbon type film, 1st coating), 6 ... Sliding surface, 7 ... Sliding surface

Claims (8)

1. An aliphatic hydrocarbon group having a peak in the region of 2900 cm ⁻¹ to 3000 cm ⁻¹ in the infrared absorption spectrum;
   Aromatic components that show a peak at mass 91.1 in the positive ion spectrum obtained by time-of-flight secondary ion mass spectrometry, and a peak at mass 115.2 in the positive ion spectrum obtained by time-of-flight secondary ion mass spectrometry An amorphous hydrocarbon film comprising at least one of the condensed ring system components having
2. In the infrared absorption spectrum further comprising a carbonyl group which exhibits peaks in the region of 1650cm ^-1 ~ 1800cm ^-1, amorphous hydrocarbon film according to claim 1.
3. The amorphous hydrocarbon film according to claim 1 or 2, comprising both the aromatic component and the condensed ring component.
4. The amorphous hydrocarbon film according to any one of claims 1 to 3, wherein the average thickness is 2 nm to 1000 nm.
5. A sliding member having a sliding surface including a first coating, formed using at least one of metal and ceramics,
   The sliding member, wherein the first coating includes the amorphous hydrocarbon film according to any one of claims 1 to 4.
6. The sliding member according to claim 5, wherein the sliding member is formed using ZrO ₂ .
7. The sliding member according to claim 5 or 6,
   A sliding member having a sliding surface that is in sliding contact with the sliding surface of the sliding member and includes a second coating made of an amorphous carbon-based film,
   The sliding system, wherein the second coating has a Young's modulus of 200 GPa to 250 GPa.
8. The second coat is the outermost surface, containing a hydroxyl group exhibiting a peak in the region of 3000 cm ^-1 ~ 4000 cm ^-1 in an infrared absorption spectrum, the sliding system of claim 7.

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