JP6736018B2 - Low friction coating manufacturing method - Google Patents

Description

The present invention relates to a method for producing a low-friction coating for producing a low-friction coating, and a sliding method for sliding a sliding surface on an amorphous carbon film.

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 Like Carbon) film is known. In Patent Document 1 below, a sliding surface including the DLC film contains an oxygen-containing organic compound or an aliphatic amine compound. A low friction sliding mechanism for supplying a low friction agent composition is described.

Further, 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 OH groups. The second sliding surface has an OH end sliding surface. By supplying an oxygen-containing compound (liquid lubricant) between the first and second sliding surfaces, a hydrogen-terminated tribofilm is formed between the first and second sliding surfaces. ..

JP, 2005-98495, A JP2012-92351A

The low-friction sliding mechanism described in Patent Document 1 and the low-friction lubrication assembly described in Patent Document 2 each attempt to reduce the friction coefficient of the sliding portion.
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 Documents 1 and 2 cannot provide low friction under the condition that 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 part) without using a lubricant. Further, it is also desired that a state where the friction coefficient is low is stably generated on the sliding surface.
An object of the present invention is to provide a low friction coating preparation how to produce low friction coating to stably exhibit a low coefficient of friction.

The invention according to claim 1 for achieving the above object is a method for producing a low friction coating (5), which dissociates and adsorbs hydrogen molecules in a hydrogen atmosphere environment to generate active hydrogen (H ⁺ ). A sliding surface (6) formed by using a metal or ceramic having a catalytic property and a sliding surface (7) including an amorphous carbon-based film (9) containing hydrocarbon molecules as a main component are arranged. the space (10) that is, in a state where the replacement process of replacing the gas atmosphere containing a hydroxyl group-containing compound and hydrogen, the space has been with the gas atmosphere containing a hydrogen hydroxyl group-containing compound, wherein A sliding step of sliding the sliding surface relative to the sliding surface with a Hertzian contact stress of 1.0 GPa or more, and the low friction coating is formed on the sliding surface by the sliding step. A method for manufacturing a low friction coating is provided.

The numbers in parentheses represent corresponding components in the embodiments described later, but this does not mean that the present invention should be limited to those embodiments. The same applies in this section below.
The invention according to claim 2 is the method for producing a low-friction coating according to claim 1, wherein the gas atmosphere further contains a hydrocarbon-based substance.

The invention according to claim 3 is the method for producing a low-friction coating according to claim 2, wherein the hydroxyl group-containing compound and the hydrocarbon-based substance contain alcohol.
The invention according to claim 4 is the method for producing a low-friction coating according to claim ₃ , wherein the alcohol contains methanol (CH ₃ OH).
The invention according to claim 5 is that the hydroxyl group-containing compound further contains water, and is generated from an aqueous solution in which the volume% concentration of the liquid methanol and the liquid methanol relative to the liquid water is 6% to 15%. The method for producing a low-friction coating according to claim 4, further comprising: gaseous methanol and gaseous water vapor. The "volume% concentration of the liquid methanol relative to the liquid methanol and the liquid water" means the volume of the liquid methanol simple substance before mixing and the volume of the liquid water simple substance before mixing. The volume of liquid methanol alone before mixing is shown with respect to the summed value. Similarly, “volume% concentration of the liquid ethanol relative to the liquid ethanol and the liquid water” means the volume of the liquid ethanol simple substance before mixing, and the volume of the liquid water simple substance before mixing, The volume of liquid ethanol alone before mixing is shown with respect to the sum of the values. Similarly, "volume% concentration of the liquid alcohol with respect to the liquid alcohol and the liquid water", the volume of the liquid alcohol simple substance before mixing, and the volume of the liquid water simple substance before mixing, Shows the volume of the liquid alcohol alone before mixing with respect to the sum of the values. Similarly, "the volume% concentration of the liquid 1-propanol and the liquid 1-propanol with respect to the liquid water" means the volume of the liquid 1-propanol alone before mixing and the volume of the liquid 1-propanol before mixing. The volume of the simple substance of water and the volume of the simple substance of 1-propanol of the liquid before mixing are shown with respect to the total value of. Similarly, "the volume% concentration of the liquid 2-propanol to the liquid 2-propanol and the liquid to the water" means the volume of the liquid 2-propanol simple substance before mixing and the volume of the liquid before mixing. 2 shows the volume of a simple substance of water and the volume of a simple substance of liquid 2-propanol before mixing with respect to a total value of the volume of the simple substance of water.

The invention according to claim 6 is the method for producing a low-friction coating according to claim 3, wherein the alcohol contains ethanol (C ₂ H ₅ OH).
In the invention according to claim 7, the hydroxyl group-containing compound further contains water, and the liquid ethanol and the aqueous ethanol having a volume% concentration of ethanol of the liquid with respect to water of 6% to 30% are generated. The method for producing a low-friction coating according to claim 6, further comprising: gaseous ethanol and gaseous water vapor.

The invention according to claim 8 includes gaseous ethanol and gaseous steam generated from an aqueous solution in which the volume% concentration of ethanol in the liquid ethanol and the liquid water is 15% to 25%. The method for producing a low friction coating according to item 7.
The invention according to claim 9 is the method for producing a low-friction coating according to claim 3, wherein the alcohol contains 1-propanol (CH ₃ CH ₂ CH ₂ OH).

The invention according to claim 10 is the method for producing a low-friction coating according to claim ₃ , wherein the alcohol contains 2-propanol (CH ₃ CH(OH)CH ₃ ).
Claim 11 is the low alcohol according to any one of claims 3, 4, 6, 9 and 10, wherein the hydroxyl group-containing compound is a gaseous alcohol generated from a solution containing the alcohol in a proportion of 100%. It is a method for manufacturing a friction coating.

A twelfth aspect of the present invention is the method for producing a low friction coating according to any one of the first to tenth aspects, wherein the hydroxyl group-containing compound contains water.
The invention according to claim 13 is the method for producing a low-friction coating according to any one of claims 1 to 12, wherein the Hertzian contact stress is 1.3 GPa to 2.4 GPa.
The invention according to claim 14 is the method for producing a low-friction coating according to any one of claims 1 to 13, wherein the amorphous carbon-based film contains a short-chain polyacetylene-based molecule as a main component.

The invention according to claim 15 is characterized in that the amorphous carbon-based film includes a coating film formed by an ionization deposition method while applying a bias voltage in an atmosphere environment of a hydrocarbon-based gas. The low friction coating manufacturing method according to any one of 1.
According to a sixteenth aspect of the present invention, the amorphous carbon-based film includes a film formed by an ionization deposition method while applying a high bias voltage in an atmosphere environment of a hydrocarbon-based gas, The low friction coating manufacturing method according to claim 15, wherein at least one of hydrogen and oxygen is added to the carbon-based film.

The invention according to claim 17 is the method for producing a low friction coating according to any one of claims 1 to 16, wherein the sliding member is formed using ZrO ₂ .
The invention according to claim 18 includes a supply step of supplying the hydroxyl group-containing compound to the space, and a supply stop step of stopping the supply of the hydroxyl group-containing compound to the space after the sliding step is started. The method for producing a low-friction coating according to any one of claims 1 to 17.

In the invention according to claim 19, in parallel with the sliding step, a supply state of supplying the hydroxyl group-containing compound to the space and a supply stop state of stopping the supply of the hydroxyl group-containing compound to the space alternate. The method for producing a low-friction coating according to any one of claims 1 to 18, further comprising the step of repeating the above step .

The invention according to claim 20 , wherein the hydroxyl group-containing compound further contains water, the methanol flows in a gas state by a first carrier gas, and the water flows in a gas state by a second carrier gas, Of the flow rate of the first carrier gas containing the gaseous methanol and the flow rate of the second carrier gas containing the gaseous water, of the flow rate of the first carrier gas containing the gaseous methanol. The low friction coating manufacturing method according to claim 4, wherein the ratio is 6% to 15%.

The invention according to claim 21 , wherein the hydroxyl group-containing compound further contains water, the ethanol flows in a gas state by a first carrier gas, and the water flows in a gas state by a second carrier gas, Of the flow rate of the first carrier gas containing the gaseous ethanol and the flow rate of the second carrier gas containing the gaseous water, of the flow rate of the first carrier gas containing the gaseous ethanol. The low friction coating manufacturing method according to claim 6, wherein the ratio is 6% to 30%.

The invention according to claim 22 includes the gaseous ethanol with respect to the sum of the flow rate of the first carrier gas containing the gaseous ethanol and the flow rate of the second carrier gas containing the gaseous water. 22. The low friction coating manufacturing method according to claim 21 , wherein the flow rate ratio of the first carrier gas is 15% to 25%.
The invention according to claim 23 is the method for producing a low-friction coating according to claim 2, wherein the hydrocarbon-based substance contains ethylene.

According to the present invention, in an atmosphere environment containing a hydroxyl group-containing compound and at least one of hydrogen and nitrogen, a sliding surface formed of a metal or ceramics can be applied to a sliding surface with a hertz of 1.0 GPa or more. Slide with contact stress. As a result, a low-friction coating that stably exhibits a low friction coefficient can be formed on the sliding surface. In other words, it is possible to stably realize sliding with a low friction coefficient.

It is sectional drawing which expands and shows the principal part of the sliding system obtained by the low friction film manufacturing method which concerns on one Embodiment of this invention. It is a figure which shows typically the structure of the film manufacturing apparatus with which the low friction film manufacturing method which concerns on one Embodiment of this invention is implemented. It is sectional drawing which shows the sliding action of a sliding member and a to-be-slipped member. It is a typical sectional view showing the composition of the 1st friction testing machine. It is a figure for demonstrating the plate test piece of the measurement object of the 1st-13th friction test. It is a graph which shows the relationship between the applied load and the measured value of a friction coefficient in a 1st friction test. It is a graph which shows the relationship between the applied load and the measured value of a friction coefficient in a 2nd friction test. It is a graph which shows the relationship between the applied load and the measured value of a friction coefficient in a 3rd friction test. It is a graph which shows the relationship between the applied load and the measured value of a friction coefficient in a 4th friction test. It is a graph which shows the relationship between the load and the measured value of a friction coefficient in a 5th friction test. It is a graph which shows the relationship between the applied load and the measured value of a friction coefficient in a 6th friction test. It is a graph which shows the relationship between the applied load and the measured value of a friction coefficient in a 7th friction test. It is a graph which shows the relationship between the applied load and the measured value of a friction coefficient in an 8th friction test. It is a graph which shows the relationship between the load and the measured value of a friction coefficient in a 9th friction test. It is a graph which shows the relationship between the load and the measured value of a friction coefficient in the 10th friction test. It is a graph which shows the relationship between the load applied and the measured value of a friction coefficient in the 11th friction test. It is a graph which shows the relationship between the load applied and the measured value of a friction coefficient in the 12th friction test. It is a graph which shows the relationship between the load applied and the measured value of a friction coefficient in the 13th friction test. It is an image figure of the optical microscope photograph of the outer surface of a pin test piece and the PLC film surface of a plate test piece after completion|finish of a 10th friction test. It is an image figure of the optical microscope photograph of the outer surface of a pin test piece and the PLC film surface of a plate test piece after completion of the 11th friction test. It is an image figure of the optical microscope photograph of the outer surface of a pin test piece and the PLC film surface of a plate test piece after completion of the 12th friction test. It is an image figure of the optical microscope photograph of the outer surface of a pin test piece and the PLC film surface of a plate test piece after completion|finish of the 13th friction test. It is a typical sectional view showing composition of the 2nd friction testing machine. It is a figure for demonstrating the upper layer of the plate test piece of the measurement object of a 14th-20th friction test. It is a figure for demonstrating the test conditions of a 14th friction test. It is a graph which shows the relationship between the load and the measured value of a friction coefficient in the 14th friction test. It is a figure for demonstrating the test conditions of the 15th and 16th friction test. It is a graph which shows the relationship between the load applied and the measured value of a friction coefficient in the 15th friction test. It is a graph which shows the relationship between the load and the measured value of a friction coefficient in the 16th friction test. It is a figure for demonstrating the test conditions of a 17th friction test. It is a graph which shows the relationship between the applied load and the measured value of a friction coefficient in a 17th friction test. It is a figure for demonstrating the test conditions of the 18th, 19th, and 20th friction tests. It is a graph which shows the relationship between the load and the measured value of a friction coefficient in the 18th friction test. It is a graph in the 19th friction test which shows the relationship between the load and the measured value of a friction coefficient. It is a graph which shows the relationship between the load applied and the measured value of a friction coefficient in the 20th 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 obtained by a low friction coating manufacturing method 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 so as to be slidable relative to the sliding member 3. The sliding member 2 and the slid member 3 may slide (move) only the sliding member 2 in a state where the slid member 3 is stationary, or the sliding member 2 is stationary. The sliding member 3 alone may be slid (moved) in the moving state, or the sliding member 3 can be moved by moving both the sliding member 2 and the sliding member 3. Alternatively, the sliding member 2 may be slid relative to each other.

The sliding member 2 includes a first base material 4 having a surface (lower surface in FIG. 1) and a low friction coating 5 that covers at least a part of the surface of the first base material 4. The first base material 4 is formed using oxide ceramics (ceramics) or metal. The oxide ceramics include, 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 chrome bearing steel material). These oxide ceramics and metals have a catalytic property of dissociating and adsorbing hydrogen molecules in a hydrogen atmosphere environment to generate active hydrogen (H ⁺ ).

The low friction film 5 is an amorphous hydrocarbon film. Low friction coating 5 is an aliphatic hydrocarbon group (e.g. alkyl group), a carbonyl group (-C (= O) -) and, the aromatic component _{(C 7 H} ^{7 +),} fused ring system component (C ₉ H ₇ ⁺ ). This aliphatic hydrocarbon group shows a peak in the region of 2900 cm ^{-1 to} 3000 cm ^{-1 in} the infrared absorption spectrum (microscopic transmission method). Carbonyl group, a peak in the region of ^{1650cm -1 ~1800cm} -1 in an infrared absorption spectrum (microscopic transmission method). The aromatic component (C ₇ H ₇ ⁺ ) shows a peak at mass 91.1 in the 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 mass 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 base material 8 having a surface (the upper surface in FIG. 1) and a PLC (Polymer-Like Carbon) film (amorphous) that covers at least a part of the surface of the second base material 8. Carbon-based film) 9. The second base material 8 is formed using a steel material such as tool steel, carbon steel, stainless steel, chrome molybdenum steel, or high carbon chrome bearing steel.

The PLC film 9 is an amorphous carbon-based film and contains short-chain polyacetylene-based molecules as a main component. PLC film 9, hydrocarbon gas (e.g. toluene _{(toluene, C 7 H 8)} ) under an atmosphere environment, while applying a low bias voltage or a high bias voltage, a coating formed by ionization vapor deposition method. 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 ^{3000cm -1 ~4000cm} -1 in an infrared absorption spectrum (microscopic transmission method). When an amorphous carbon-based film is produced 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 flat flat surfaces as shown in FIG. 1, or spherical surfaces or other curved surfaces.

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 performs the sliding operation under the non-lubricated condition.
Examples of the sliding system 1 include bearings, seals, flywheels, scissors, plunger pumps and artificial joints. Examples of the bearing include a ball bearing, a roller bearing including a tapered roller bearing, a bearing with a separator, and a slide bearing.

When a ball bearing is adopted as the sliding system 1, the sliding surface 7 on which the PLC film 9 is arranged includes the inner surface of the cage, and the sliding surface 6 is made of oxide ceramics (ZrO ₂ etc.) or metal. The outer surface of a ball made of (SUJ2, palladium, etc.) may be included. Further, 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, the PLC film 9 is used. The sliding surface 7 on which the slider is arranged includes the guided surface of the cage, and the sliding surface 6 is made of oxide ceramics (ZrO ₂ or the like) or metal (SUJ2, palladium or the like) that guides the cage. It may include a wheel guide surface.

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

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

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

When an artificial joint is adopted as the sliding system 1, the sliding surface 7 on which the PLC film 9 is arranged includes the contact surface on the receiving side, and the sliding surface 6 is made of oxide ceramics (ZrO ₂ or the like) or It may include a bone-side contact surface made of metal (SUJ2, palladium, etc.).
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. However, the sliding surface 6 is provided on the other member and the sliding surface 7 is provided on one member. It may be provided in the member.

FIG. 2 is a diagram schematically showing the configuration of the film manufacturing apparatus 11 in which the low friction coating manufacturing method according to the embodiment of the present invention is carried out. The film manufacturing apparatus 11 includes a box-shaped chamber 12 having an internal space. The sliding member 2 and the slid member 3 are housed in the internal space (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 arranged in the internal space 10 of the chamber 12. The slidable member 3 carried into the internal space 10 of the chamber 12 is placed on the holding table 13 and held by the holding table 13. The sliding member 2 is placed on the sliding member 3.

The film manufacturing apparatus 11 drives the sliding member 2 so as 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 for applying a pressing load of the sliding member 2 to the sliding member 3 to the sliding member 2. The drive mechanism 14 is, for example, a mechanism including a motor. Further, the film manufacturing apparatus 11 includes a control device 16 that controls the operation of the apparatus provided in the film manufacturing apparatus 11 and the opening/closing of valves. The drive mechanism 14 is, for example, a linear motion device that is a combination of a motor and a ball screw. The load applying mechanism 15 is, for example, a weight.

At the bottom of the chamber 12, an exhaust duct 17 for leading out gas in the internal space 10 of the chamber 12 is provided. Although the exhaust duct 17 is provided at the bottom of the chamber 12 in FIG. 2, it may be provided at a position other than the bottom of the chamber 12.
In FIG. 2, the driving mechanism 14 and the load applying mechanism 15 are provided, but in the state where the load is applied between the sliding member 2 and the slid member 3, the sliding member 2 and the slid member If it is configured to slide with the member 3, it is not necessary to provide the drive mechanism 14 and the load applying mechanism 15.

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

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, the alcohol valve 28 and/or the water valve 30 are opened so that a small flow rate of the alcohol gas and hydrogen gas (H ₂ ) which is a carrier gas supplied from the outside and/or a small flow rate of the steam are supplied from the outside. Hydrogen gas (H ₂ ) which is a carrier gas to be generated is supplied into the processing gas introduction pipe 19 and sufficiently mixed (stirred) with a large flow rate of hydrogen gas (H ₂ ) in the process of flowing through the processing gas introduction pipe 19. To be done. By this mixing, a special hydrogen gas (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 produced special hydrogen gas is introduced into the internal space 10 of the chamber 12 through the introduction port 32 formed at the tip of the processing gas introduction pipe 19. As a result, 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 large, a large flow rate of nitrogen from the nitrogen gas pipe 33 is supplied to the processing gas introduction pipe 19. At this time, by opening the alcohol valve 28 and/or the water valve 30, a small flow rate of the alcohol gas and nitrogen gas (N ₂ ) which is a carrier gas supplied from the outside and/or a small flow rate of the steam is supplied from the outside. Nitrogen gas (N ₂ ) which is a carrier gas to be supplied is supplied into the processing gas introduction pipe 19 and sufficiently mixed (stirred) with a large flow rate of nitrogen gas (N ₂ ) in the process of flowing through the processing gas introduction pipe 19. To be done. By this mixing, special nitrogen gas (gas containing nitrogen and alcohol (compound containing hydroxyl group) and/or water (compound containing hydroxyl group) is generated. Alcohol and/or water are vaporized in the produced special nitrogen gas. The generated special nitrogen gas is introduced into the internal space 10 of the chamber 12. As a result, 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 with the hydrogen gas valve 24 and the nitrogen gas valve 34 opened, special nitrogen/hydrogen gas (nitrogen and hydrogen, and alcohol (hydroxyl group-containing compound) and/or Alternatively, a gas containing water (a compound containing a hydroxyl group) is generated. The produced special nitrogen/hydrogen gas is introduced into the internal space 10 of the chamber 12. As a result, 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 slid 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. Please refer to FIG. 3A and FIG. 3B as appropriate.
When the low friction coating 5 is manufactured (formed) using the film manufacturing apparatus 11, the sliding member 2 and the slid member 3 are carried into the internal space 10 of the chamber 12. The slid member 3 that has been carried in is placed on the holding table 13 with the sliding surface 7 facing upward, and is held by the holding table 13. Further, the sliding member 2 that has been carried in 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 being loaded. That is, the sliding surface 6 is made of oxide ceramics or metal.

After the sliding member 2 and the slid member 3 are loaded 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 step). For example, it is assumed that the processing gas contains a special hydrogen gas, and in this special hydrogen gas, a trace amount of gaseous alcohol and a trace amount of gaseous steam are added to the hydrogen gas. This special hydrogen gas is an alcohol container with respect to the sum of the flow rate of the carrier gas containing gaseous alcohol in the alcohol container 37 and the flow rate of the carrier gas containing gaseous water in the water container 38, in addition to hydrogen gas. In 37, the gas flow rate of the carrier gas containing the gaseous alcohol [alcohol/(alcohol+water)] is, for example, 4 to 44% of the gaseous alcohol and the gaseous water vapor.

The processing gas supplied into the chamber 12 spreads throughout the internal space 10 of the chamber 12. As a result, the atmosphere (Air) in the internal space 10 of the chamber 12 is replaced with the atmosphere containing the processing gas (replacement step). The process gas does not contain oxygen.
After the internal space 10 of the chamber 12 is filled with the atmosphere of the processing gas (in the state where the internal space 10 is in the atmosphere of the processing gas), the control device 16 controls the drive mechanism while continuing the supply of the processing gas. 3A, the sliding surface 7 (sliding member 3) is applied with a pressing load from the sliding surface 6 (sliding member 2) while the sliding surface 7 (sliding member 3) is pressed as shown in FIG. 3A. The sliding of the sliding surface 6 with respect to 7 (sliding step) is started. The Hertzian contact stress generated between the sliding surface 6 and the sliding surface 7 during sliding due to the application of the pressing load is 1.0 GPa or more. More preferably, the Hertzian contact stress is 1.3 GPa to 2.4 GPa.

When a predetermined period (for example, 30 minutes) has elapsed from the start of sliding of the sliding surface 6, the control device 16 closes the alcohol valve 28 and the water valve 30 to stop the supply of alcohol and water to the internal space 10. Yes (supply stop step).
As the sliding surface 6 slides on the sliding surface 7, the sliding surface 6 slides on the sliding surface 7 due to the catalytic action of the sliding surface 6 (ZrO ₂ etc.). A low-friction coating 5 is formed on. The low friction coating 5 exhibits a remarkably 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 exhibited. In other words, as a result of sliding of the sliding surface 6 with respect to the sliding surface 7, the friction coefficient gradually decreases with friction, and FFO can be exhibited.

The low friction coating 5 corresponds to FPF-2 described later. The low-friction coating 5 is a transparent film that has the same hardness as the PLC film 9 and exhibits interference fringes. Blister (air bubbles) is generated on the surface and inside of the low-friction coating 5.
The inventors of the present application consider the mechanism of formation of such a low friction coating 5 (expression of FFO) as follows.

That is, as the sliding surface 6 slides (friction), the outermost surface of the PLC film 9 becomes frictional wear powder and is transferred to the sliding surface 6. That is, the 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 rub. The metal (SUJ2, palladium, etc.) or oxide ceramics (ZrO ₂ ) forming the sliding surface 6 has a catalytic property capable of dissociating and adsorbing hydrogen molecules to generate active hydrogen. Therefore, as a result of sliding the PLC film 9 on the sliding surface 6, active hydrogen is present at the sliding interface due to the catalytic action of the sliding surface 6.

The alcohol contained in the atmosphere of the internal space 10 is hydrolyzed by the acid catalyst action of the active hydrogen on the sliding surface 6, and a volatile gas is formed in the transfer film. It is considered that a gas molecule layer of volatile gas is formed on the friction surface (sliding interface) of the transfer film. The thickness of this gas molecule layer is on the level of several molecules, and it is considered that FFO is expressed by the gas lubrication of this volatile gas layer at the level of a single molecule. That is, the low friction coating 5 is formed on the basis of the transfer film including the volatile gas layer.

Further, 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, water (water) can be removed from the atmosphere of the internal space 10. Stabilization of these oxides (ZrO ₂ ) or metals (SUJ, palladium) can be achieved by removing water (water) that can be a catalyst poison that weakens the catalytic action.

A more specific FFO expression mechanism is as follows.
When the active hydrogen on the sliding surface 6 comes into contact with the C ₂ Hx to C ₄ Hx fragment having the C=C bond of the PLC film 9, the π bond of the C=C bond portion is catalytically reduced and is directed to the sliding interface. Two C—H bonds (cis addition reaction) occur. Since the C=C bond having a strong flatness becomes a C-C bond (σ bond), the degree of freedom of deformation of the fragment increases, and as a result, a volatile gas layer is formed at the friction interface.

Further, the repulsive force between the hydrogen atoms of the C—H bond (repulsive force due to Van der Waals force) is also considered to be a factor in the expression of FFO. The formation of C—C bond fragments that volatilize readily by rubbing is also believed to contribute to the expression of FFO.
When a predetermined period has elapsed from the start of sliding of the sliding surface 6, the control device 16 closes the open valves (hydrogen gas valve 24, alcohol valve 28, water valve 30, nitrogen gas valve 34, etc.) to introduce the processing gas. The introduction of the processing gas from the pipe 19 is stopped. After that, the control device 16 causes the sliding member 2 and the slid member 3 to be carried out of the internal space 10 of the chamber 12.

When methanol is used as alcohol, regarding the gaseous methanol and gaseous water contained in the processing gas, the flow rate of the carrier gas containing gaseous methanol in the alcohol container 37 and the carrier gas containing gaseous steam in the water container 38. It is preferable that the ratio of the flow rate of the carrier gas containing the gaseous methanol in the alcohol container 37 to the total of the flow rate of 6 to 15%. Further, 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 steam in the water container 38 is calculated by adding the carrier gas containing gaseous methanol to the alcohol container 37. FFO can be expressed even if the ratio of the flow rates is any other value (this value may include 100%).

When ethanol is used as the alcohol, regarding the gaseous ethanol and the gaseous water contained in the processing gas, the flow rate of the carrier gas containing the gaseous ethanol in the alcohol container 37 and the carrier gas containing the gaseous steam in the water container 38. It is preferable that the ratio of the flow rate of the carrier gas containing ethanol in the alcohol container 37 to the total of the flow rate of 6 to 30%. Further, the total flow rate of the carrier gas containing the gaseous ethanol in the alcohol container 37 and the flow rate of the carrier gas containing the gaseous water vapor in the water container 38 is calculated by adding the carrier gas containing the gaseous ethanol in the alcohol container 37. FFO can be expressed even if the ratio of the flow rates is any other value (this value may include 100%). 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 steam in the water container 38. When the gas flow ratio is 15% to 25%, FFO can be expressed in a stable state for a long period of time.

Next, the 1st-13th friction test performed using the 1st friction tester 41 is demonstrated.
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 to thirteenth 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 manufacturing method.

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

The first friction tester 41 includes, for example, a cylindrical chamber 45, and the pin test piece 44 is housed 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 arranged in the opening 48. A holding base 49 for holding the plate test piece 42 is arranged at the bottom of the chamber 45. A gas introduction pipe 51 is provided so as to penetrate 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. In the first line 52, 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 the first line 52 is interposed. In the second line 53, 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 are an aqueous solution of liquid alcohol and water, and gaseous alcohol and gaseous steam vaporized from the aqueous solution. 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. By flowing hydrogen gas 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 second valve 57 and opening the first valve 54, hydrogen gas containing gaseous alcohol and gaseous water vapor is supplied into the chamber 45 through the gas introduction pipe 51. The chamber 45 is provided so that the atmosphere in the chamber 45 can be controlled.

As the plate test piece 42, as shown in FIG. 5A, a silicon substrate 61 having a two-layer film 43 formed on its surface was used. The two-layer film 43 is a hard carbon-based film having a two-layer structure. The lower layer side of the two-layer film 43 is the 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 formed by performing an ionization vapor deposition method (PVD method) using a mixture of toluene and trimethylsilane (Si(CH ₃ ) ₄ ) at a gas flow rate ratio of 2:3 as a source gas. Has been formed. The PLC film 63 is formed by performing an ionization vapor deposition method using only toluene as a source gas. The bias voltage during the PLC film formation was set to -0.4 kV (low bias voltage).

Processing pressure (Deposition pressure, Pa) during film formation of the Si-DLC film 62 and PLC film 63, bias voltage (Bias voltage, kV) during film formation, processing temperature (Heater temperature, K) during film formation, Film thickness (nm), Indentation hardness (GPa), Young's modulus (GPa), Raman spectrum G band peak position (G-peak position, cm ^-1 ), Raman spectrum FWHM(G), cm ^{−1 of} G band, peak intensity ratio (I(D)/I(G)) of D band and G band of Raman spectrum, estimated hydrogen content (at. %) are shown in FIG. 5B, respectively.

After the plate test piece 42 was set on the first friction tester 41 with the surface on which the two-layer film 43 was formed as the test surface, the friction speed was 8.0 mm/s, the friction stroke was 4.0 mm, and the flow rate of gas supplied to the chamber 45 was set. Under the test condition of approximately 2.0 to 6.2 (liter/min) and no lubrication, the magnitude of the load applied to the surface of the plate test piece 42 via the pin test piece 44 is 19.6N to 58.8N. In the range, the following first to thirteenth friction tests (high-load tests up to 28200 times) were performed while gradually increasing by 1.96 N units, and the expression state of FFO was investigated.

First, the first to fourth friction tests will be described. The temperature in the chamber 45 was set to 20°C ± 5°C. In the first to fourth friction tests, methanol was used as the alcohol, and the concentration of methanol contained in the processing gas (in this case, a special hydrogen gas containing alcohol and water; the same applies hereinafter) was changed.
In the first to fourth friction tests, the gas flow rate of the first line 52 was 8 (liter/minute), and the gas flow rate of the second line 53 was 200 sccm. Hydrogen gas was flown through the first line 52. Hydrogen gas was passed through the second line 53 as a carrier gas.

In addition, in the first to fourth friction tests, a float type flow meter was used as the second flow meter 59 for detecting the gas flow rate of the second line 53. The lower limit of detection of the second flow meter 59 was 200 sccm. Therefore, the gas flow rate of the second line 53 that is feedback-controlled based on the second flow meter 59 cannot be controlled to a constant flow rate. Therefore, in the first to fourth friction tests, it is presumed that the gas flow rate of the second line 53 gradually decreases after the start of the test.
<First friction test>
An alcohol/water container 60 was charged with 20 cc of water and 1 cc of methanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas includes liquid methanol and gaseous methanol generated from an aqueous solution whose volume% concentration of liquid methanol to liquid water is 4.8%. Gaseous water vapor is included.
<Second friction test>
An alcohol/water container 60 was charged with 10 cc of water and 1 cc of methanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas includes liquid methanol and gaseous methanol generated from an aqueous solution in which the volume% concentration of liquid methanol to liquid water is 9.1%. Gaseous water vapor is included.
<Third friction test>
An alcohol/water container 60 was charged with 10 cc of water and 2 cc of methanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas includes liquid methanol and gaseous methanol generated from an aqueous solution in which the volume% concentration of liquid methanol to liquid water is 16.7%. Gaseous water vapor is included.
<Fourth friction test>
Alcohol/water container 60 was charged with 10 cc of water and 10 cc of methanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas includes liquid methanol and gaseous methanol and gaseous gas generated from an aqueous solution in which the volume% concentration of liquid methanol to liquid water is 50%. Water vapor is included.

6 to 9 are graphs showing the relationship between the applied load (Load) and the measurement value of the friction coefficient (Friction coefficient) in the first to fourth friction tests. In the first friction test, as shown in FIG. 6, the friction coefficient was 0.01 or more and FFO (super low friction state) did not appear under any of the applied load conditions.
In the second friction test, as shown in FIG. 7, when the load reached about 50 N, the friction coefficient sharply decreased and FFO developed. The coefficient of friction when FFO developed was 5×10 ^{−4 to} 7×10 ⁻⁴ . After that, even if the load was increased, FFO continued to develop. After the load reached 58.8 N, the load was kept constant at a high load, but FFO continued to be stably expressed. After the development of FFO continued for 70 minutes, the second friction test was finished.

In the third friction test, as shown in FIG. 8, the friction coefficient was 0.01 or more and FFO did not appear under any of the applied load conditions.
In the fourth friction test, as shown in FIG. 9, the friction coefficient was 0.01 or more and FFO did not occur under any of the applied load conditions.
From the 1st to 4th friction tests, when methanol is used as alcohol, the volume% concentration of liquid methanol to liquid methanol and liquid water contained in the special hydrogen gas containing alcohol and water is 6 to 15%. FFO is easy to develop when it contains gaseous methanol and gaseous steam generated from an aqueous solution, and especially when the volume% concentration of liquid methanol and liquid methanol to liquid water is about 9%. I understand.

Next, the fifth to ninth friction tests will be described. The temperature in the chamber 45 was set to 20°C ± 5°C. In the fifth to ninth friction tests, ethanol was used as alcohol and the concentration of ethanol contained in the special hydrogen gas was changed.
In the fifth to ninth friction tests, the gas flow rate of the first line 52 was set to 8 (liter/minute), and the gas flow rate of the second line 53 was set to 200 sccm.

In addition, in the fifth to ninth friction tests, a float type flow meter was used as the second flow meter 59 for detecting the gas flow rate of the second line 53. The lower limit of detection of the second flow meter 59 was 200 sccm. Therefore, the gas flow rate of the second line 53 that is feedback-controlled based on the second flow meter 59 cannot be controlled to a constant flow rate. Therefore, in the fifth to ninth friction tests, it is presumed that the gas flow rate of the second line 53 gradually decreases after the start of the test.
<Fifth friction test>
Alcohol/water container 60 was charged with 10 cc of water and 1 cc of ethanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas includes liquid ethanol and gaseous ethanol generated from an aqueous solution in which the volume% concentration of liquid ethanol to liquid water is 9.1%. Gaseous water vapor is included.
<Sixth friction test>
An alcohol/water container 60 was charged with 10 cc of water and 2 cc of ethanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas includes liquid ethanol and gaseous ethanol generated from an aqueous solution in which the volume% concentration of liquid ethanol to liquid water is 16.7%. Gaseous water vapor is included.
<Seventh friction test>
Alcohol/water container 60 was charged with 10 cc of water and 3 cc of ethanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas includes liquid ethanol and gaseous ethanol generated from an aqueous solution in which the volume% concentration of liquid ethanol to liquid water is 23.1%. Gaseous water vapor is included.
<Eighth friction test>
Alcohol/water container 60 was charged with 10 cc of water and 5 cc of ethanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas includes liquid ethanol and gaseous ethanol generated from an aqueous solution in which the volume% concentration of liquid ethanol to liquid water is 33.3%. Gaseous water vapor is included.
<Ninth friction test>
Alcohol/water container 60 was charged with 10 cc of water and 10 cc of ethanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas includes liquid ethanol and gaseous ethanol generated from an aqueous solution in which the volume% concentration of liquid ethanol to liquid water is 50%. Water vapor is included.

10 to 14 are graphs showing the relationship between the applied load (Load) and the measured value of the friction coefficient (Friction coefficient) in the fifth to ninth friction tests.
In the fifth friction test, as shown in FIG. 10, when the load reached about 27 N, the friction coefficient sharply decreased and FFO developed. The coefficient of friction when FFO occurs is about 5×10 ⁻⁴ . After that, the friction coefficient gradually decreased as the load increased, but as soon as the friction coefficient entered the order of 10 ^-5 , the coefficient of friction drastically increased and decreased between the order of 10 ^-4 and 10 ^-5. Was repeated. When the load reached about 42 N, the friction coefficient increased to about 8×10 ⁻² , so the fifth friction test was terminated.

In the sixth friction test, as shown in FIG. 11, when the load reached about 50 N, the friction coefficient sharply decreased and FFO developed. After that, the expression of FFO was maintained even if the load was increased. After the load reaches 58.8 N, if kept constant at the high load, the coefficient of friction drops to the order of 10 ⁻⁵ . After that, an unstable state was observed in which the friction coefficient gradually increased, so the load was gradually decreased, but the instability of the friction coefficient was not eliminated. After that, since the friction coefficient increased to 0.02, the sixth friction test was finished.

In the seventh friction test, as shown in FIG. 12, when the load reached about 40 N, the friction coefficient sharply decreased and FFO developed. After that, the friction coefficient repeatedly increased and decreased between 10 ⁻³ order and 10 ⁻⁵ order, but when the load reached about 50 N, the rapid increase and decrease disappeared and the friction coefficient became 10 ^−5. It became stable on the order. After the load reached 58.8 N, the friction coefficient was stable on the order of 10 ⁻⁵ even if the load was kept constant at a high load. That is, in the seventh friction test, the value of the friction coefficient when FFO occurred was extremely small.

When 25 minutes passed after the load reached 58.8 N, the friction coefficient increased to the order of 10 ⁻⁴ . Therefore, the amount of hydrogen gas containing ethanol and water was increased. Then, the friction coefficient again decreased to the order of 10 ⁻⁵ .
It is considered that the increase in the friction coefficient is such that the low-friction coating (equivalent to the low-friction coating 5 in FIG. 1) formed on the sliding surface 6 (see FIG. 1 and the like) peels off with sliding. It can be inferred that the low friction coating 5 was not regenerated on the sliding surface 6 because ethanol and water were depleted on the sliding surface 6 (sliding interface). It is speculated that increasing the supply of ethanol and water promoted the regeneration of the low-friction coating 5 on the sliding surface 6, and therefore the coefficient of friction dropped again to the order of 10 ⁻⁵ .

The friction coefficient sharply increased 90 minutes after the load reached 58.8 N, so the seventh friction test was terminated.
In the eighth friction test, as shown in FIG. 13, the friction coefficient was 0.01 or more and FFO did not appear under any of the applied load conditions.
In the ninth friction test, as shown in FIG. 14, when the load reached about 45 N, the friction coefficient sharply decreased and FFO developed. At the time of FFO expression, the friction coefficient was as low as about 1×10 ⁻⁴ , but as the load increased, the friction coefficient increased to the order of 10 ⁻³ . After the load reaches 58.8 N, if the load is kept constant at the high load, the friction coefficient decreases and FFO reappears. After that, since the friction coefficient sharply increased, the ninth friction test was finished.

Further, from the fifth to ninth friction tests, when ethanol is used as the alcohol, an aqueous solution containing about 6 to about 30% by volume of liquid ethanol and liquid ethanol contained in the special hydrogen gas. FFO is liable to develop when it contains gaseous ethanol and gaseous water vapor generated from water. Particularly, it is generated from an aqueous solution having a volume% concentration of liquid ethanol to liquid ethanol and liquid water of about 15 to about 25%. It was found that FFO is likely to develop when it contains gaseous ethanol and gaseous steam. It was also found that it has load resistance within this concentration range.

Further, from the seventh friction test, it is found that the supply of “ethanol+water” to the sliding surface 6 and the sliding surface 7 is necessary for the expression of FFO. From this, it is understood that it is necessary to constantly supply alcohol and water to the sliding surface 6 and the sliding surface 7 in order to maintain the developed FFO.
Next, the tenth to thirteenth friction tests will be described. The temperature in the chamber 45 was set to 20°C ± 5°C. In the tenth to thirteenth friction tests, the types of alcohol contained in the special hydrogen gas were methanol, ethanol, 1-propanol and 2-propanol, respectively.

Further, in the tenth to thirteenth friction tests, a mass flow meter (Fujikin TM39 Co., Ltd.) was used as the second flow meter 59 for detecting the gas flow rate of the second line 53.
In the tenth to thirteenth friction tests, the gas flow rate of the first line 52 was set to 6 (liter/min) and the gas of the second line 53 was used during the period from the start of the test until the number of frictions was 500 (familiar process) The flow rate was set to 200 sccm, and the gas flow rate of the second line 53 was set to 100 sccm while the gas flow rate of the first line 52 was 6 (liter/min) during the period from the rub count 500 times to the end of the test. At this time, between the friction number up to 500 times and after that, the liquid alcohol of the aqueous solution and the liquid against the liquid water, which are the bases of the gaseous alcohol and the gaseous steam generated from the aqueous solution, which are contained in the special hydrogen gas. The volume% concentration of the alcohol is unchanged.
<Tenth friction test>
An alcohol/water container 60 was charged with 10 cc of water and 3 cc of methanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas is gas methanol and gas generated from an aqueous solution in which the volume% concentration of liquid methanol is 23.1% with respect to liquid methanol and liquid water. And water vapor.
<Eleventh friction test>
Alcohol/water container 60 was charged with 10 cc of water and 3 cc of ethanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas is a gaseous ethanol and a gaseous ethanol generated from an aqueous solution in which the volume% concentration of liquid ethanol is 23.1% with respect to liquid ethanol and liquid water. And water vapor.
<Twelfth friction test>
Alcohol/water container 60 was charged with 10 cc of water and 3 cc of 1-propanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas is a gas generated from an aqueous solution in which the volume% concentration of liquid 1-propanol and liquid 1-propanol with respect to liquid water is 23.1%. 1-propanol and gaseous water vapor are included.
<Thirteenth friction test>
Alcohol/water container 60 was charged with 10 cc of water and 3 cc of 2-propanol. That is, in the special hydrogen gas supplied to the chamber 45, the special hydrogen gas is a gas generated from an aqueous solution in which the volume% concentration of liquid 2-propanol to liquid 2-propanol and liquid water is 23.1%. 2-propanol and gaseous water vapor are included.

15 to 18 are graphs showing the relationship between the applied load (Load) and the measured value of the friction coefficient (Friction coefficient) in the tenth to thirteenth friction tests.
In the tenth friction test, as shown in FIG. 15, FFO once developed under the condition of a load of 19.6 N, but this FFO immediately disappeared. Then, when the load was increased, when the load reached 33.3 N, the friction coefficient suddenly decreased and FFO was developed. After that, the expression of FFO was maintained even if the load was increased. At the time when the load reached 56.8 N, a sharp increase in the friction coefficient was observed, so the 10th friction test was terminated.

In the eleventh friction test, as shown in FIG. 16, when the load reached 35.3 N, the friction coefficient sharply decreased and FFO developed. After that, the expression of FFO was maintained even if the load was increased. At the time when the load reached 63.7 N, a sharp increase in the friction coefficient was observed, so the 11th friction test was terminated. The expression time of FFO was 15 minutes.
In the twelfth friction test, as shown in FIG. 17, when the load reached 35.3 N, the friction coefficient sharply decreased and FFO developed. After that, the expression of FFO was maintained even if the load was increased. At the time when the load reached 63.7 N, a sharp increase in the friction coefficient was observed, so the 12th friction test was terminated. The expression time of FFO was 15 minutes.

In the thirteenth friction test, as shown in FIG. 18, FFO once developed under the condition of a load of 19.6 N, but this FFO immediately disappeared. After that, when the load was increased, FFO was developed when the load reached 23.5N. This FFO disappeared when the load reached 23.5 N, but with the increase of the load thereafter, FFO reappeared at the time when the load reached 31.4 N. After that, the expression of FFO was maintained even if the load was increased. At the time when the load reached 63.7 N, a sharp increase in the friction coefficient was observed, so the 13th Friction Test was terminated. In the load range of 31.4 N to 63.7 N, the FFO expression time was 20 minutes.

From the tenth to thirteenth friction tests, it is understood that FFO is exhibited regardless of which of alcohol, methanol, ethanol, 1-propanol and 2-propanol is used.
Further, it is understood that FFO is stably expressed in alcohol as the molecular weight (that is, the number of carbon atoms) of hydrocarbon increases (methanol<ethanol<1-propanol=2-propanol).

Further, FFO was more stably expressed in its isomer, 2-propanol, than in 1-propanol. It is considered that the stability of FFO expression is also influenced by the presence of OH groups in the molecular structure.
In the above-mentioned first to thirteenth friction tests, expression of FFO was observed in the second, fifth to seventh and ninth to thirteenth friction tests. The expression status of this FFO will be described with reference to FIG. 3B.

As the sliding surface 6 slides on the sliding surface 7, a relatively thick friction polymer film (hereinafter referred to as “FPF”) slides due to the catalytic action of the sliding surface 6 made of ZrO ₂ or the like. It is formed on the moving surface 6. The FPF at the initial stage of sliding (same as the initial stage of familiarization) is defined as "FPF-1". The friction coefficient of FPF-1 is on the order of 10 ^-1 . FPF-1 is a black film, which is softer than the PLC film 9. FPF-1 is formed under a hydrogen gas atmosphere containing alcohol and water.

As the pressing load increases, the maximum Hertzian contact stress on the sliding surface 7 also increases. When the pressing load exceeds a predetermined value, the FPF deteriorates. This FPF is defined as "FPF-2". FPF-2 (corresponding to the "low friction coating 5") is a transparent film that exhibits interference fringes, and has the same hardness as the PLC film 9. Blister (air bubble) is formed on the surface of FPF-2 and inside FPF-2. From the first to thirteenth embodiments, it is estimated that the load at which FPF-1 is transformed into FPF-2 is about 12N. The maximum Hertzian contact stress when the load is 12 N is 1.3 GPa. It is considered that the transformation from FPF-1 to FPF-2 can be started when the maximum Hertzian contact stress is about 1.0 GPa. When the maximum Hertz contact stress is less than 1 GPa, stable FFO cannot be expressed. The maximum Hertzian contact stress when the load is 60 N is 2.4 GPa.

19 to 22 are image diagrams of optical microscope photographs of the PLC film 9 surface on the outer surface of the pin test piece 44 and the surface of the plate test piece 42 after completion of the tenth to thirteenth friction tests. FIG. 19A, FIG. 20A, FIG. 21A and FIG. 22A show image micrographs of the PLC film 9 surface, and FIGS. 19B, 20B, 21B and 22B show optical micrographs of the plate test piece 42 surface. The image figure is shown.

From FIGS. 19 to 22, it was found that different kinds of alcohols formed different kinds of films on the outer surface of the pin test piece 44.
Further, when 1-propanol was used as the alcohol, as shown in FIG. 21A, generation of blisters (air bubbles) was observed on the outer surface of the pin test piece 44. From this, it can be inferred that a volatile substance (volatile gas) is present near the sliding interface on the outer surface of the pin test piece 44.

Next, 14th to 20th friction tests performed using the second friction tester 141 will be described. The temperature in the chamber 45 was set to 20°C ± 5°C.
FIG. 23 is a schematic cross-sectional view showing the configuration of the second friction tester 141. Portions of the second friction tester 141 that are common to the first friction tester 41 are designated by the same reference numerals as in FIG. 4, and description thereof will be omitted. 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.

The gas introduction pipe 51 of the air supply system is provided with a first line 52 to which hydrogen gas is supplied, a third line 101 to which nitrogen gas is supplied, and a carrier gas containing gaseous alcohol and gaseous water vapor. No. 4 is supplied with hydrogen gas, a fifth line 103 is supplied with hydrogen gas as a carrier gas containing gaseous alcohol but not gaseous steam, and gaseous steam (distilled water A second line 104 to which hydrogen gas is supplied as a carrier gas containing (based on) but no gaseous alcohol.

In the third line 101, 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 line 101 of No. 3 is interposed.
In the fourth line 102, 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, and a fourth valve 108 A fourth flow meter 110 for detecting the flow rate of hydrogen gas in the line 102 of No. 4, and the presence of gaseous alcohol and gaseous water vapor in which liquid alcohol (ethanol) and liquid water (distilled water) are stored. Alcohol/water container 111 is installed. 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 are an aqueous solution of liquid alcohol and liquid water, and gaseous alcohol and gaseous steam vaporized from the aqueous solution. In the alcohol/water container 111, liquid ethanol and liquid water are mixed at a volume ratio of 3:10. The volume ratio of “ethanol+water” contained in the processing gas flowing through the fourth line 102 is such that the volume of liquid ethanol alone before mixing=3 and the volume of liquid water alone before mixing=10. It contains gaseous ethanol and gaseous steam vaporized from the mixed aqueous solution. Such a processing gas may be hereinafter referred to as "hydrogen gas containing ethanol (23%@) generated from an aqueous solution having a volume concentration of 23% ethanol".

In the fifth line 103, 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, A fifth flow meter 114 for detecting the flow rate of hydrogen gas in the line 103 of No. 5 and an alcohol container 115 in which only liquid alcohol (ethanol) is stored and in which gaseous alcohol exists are interposed. .. Since the alcohol container 115 does not contain water except water which cannot be removed from ethanol, the process gas flowing through the fifth line 103 contains gaseous ethanol but almost no water. Hereinafter, such a processing gas may be referred to as “hydrogen gas containing ethanol (100%@) generated from a 100% ethanol volume concentration liquid”.

In the sixth line 104, a sixth valve 116 for opening and closing the sixth line 104, a sixth flow rate adjusting valve 117 for adjusting the flow rate of hydrogen gas in the sixth line 104, A sixth flow meter 118 for detecting the flow rate of hydrogen gas in the line 104 of No. 6 and a water container 119 in which only liquid water (distilled water) is stored and in which gaseous steam exists are interposed. There is. Since the water container 119 does not contain alcohol, the processing gas flowing through the sixth line 104 contains gaseous water vapor but does not contain ethanol. Such a processing gas may be hereinafter referred to as "hydrogen gas containing water".

By selectively switching the first valve 54 and the third valve 105, the main component of the atmosphere in the chamber 45 can be switched between hydrogen and nitrogen. Further, by opening one or more of the fourth to sixth valves 108, 112, 116, the component ratio of alcohol and water contained in the atmosphere in the chamber 45 can be controlled. In addition to opening these valves 108, 112 and 116, by adjusting the opening of the flow rate adjusting valves 109, 113 and 117, the component ratio of alcohol and water contained in the atmosphere in the chamber 45 can be controlled more finely. ..

FIG. 24: is a figure for demonstrating the upper layer of the plate test piece of the measurement object of the 14th-20th friction tests.
The plate test piece 42 to be measured includes the two-layer film 43 made of a hard carbon-based film having a two-layer structure on the surface side as described with reference to FIG. 5A. In the fifteenth to twentieth friction tests, the Si-DLC film forming the lower layer of the two-layer film 43 has the same structure as the Si-DLC film 62 (see FIG. 5A), The PLC (Polymer-Like-Carbon) film 163 forming the upper layer (Surface layer) is partly different from the PLC film 63 (see FIG. 5A) in the manufacturing method.

The main difference between the method of forming the PLC film 163 and the method of forming the PLC film 63 is that a high bias voltage (-4.0 kV) is adopted as the bias voltage (Bias voltage) in the ionization deposition method (PVD method). is there.
In the fourteenth to twentieth friction tests, three types of films were prepared as the PLC film: the first PLC film 163A, the second PLC film 163B, and the third PLC film 163C. The first PLC film 163A has no additive (simply “PLC”), the second PLC film 163B has hydrogen added (H-PLC), and the third PLC film 163C has oxygen. Is added (O-PLC). The method of forming these films is as shown in FIG.

The plate test piece 42 was set on the second friction tester 141 with the surface on which the two-layered film 43 was formed as the test surface, and then the friction speed was 8.0 mm/s, the friction stroke was 4.0 mm, and there was no lubrication under the test conditions. Below, while increasing the magnitude of the load applied to the surface of the plate test piece 42 through the pin test piece 44 from 19.6N to 63.7N in steps of 1.96N, the 14th to 20th frictions are performed. A test (a high load test up to 28200 times) was conducted to examine the FFO expression status.

In the 14th to 17th friction tests of the 14th to 20th friction tests, a familiar environment (Run-in environment) from the start of the test to the expression of FFO and an FFO environment (FFO environment) after the expression of FFO. In between, the kind and/or the flow rate of the processing gas supplied into the chamber 45 are changed.
<Fourteenth friction test>
FIG. 25 is a diagram for explaining the test conditions of the fourteenth friction test.

As shown in FIG. 25, in a familiar environment (Run-in environment) in the fourteenth friction test, nitrogen gas was supplied at a large flow rate (5 slm) as a main flow into the chamber 45, and a 23% ethanol volume concentration aqueous solution was used. Hydrogen gas (23%@) containing generated ethanol is supplied at a medium flow rate (180 sccm) as a subflow. Further, in the FFO environment (FFO environment), nitrogen gas is supplied as a main flow into the chamber 45 at a large flow rate (5 slm), and hydrogen gas containing ethanol (23%@) generated from a 23% ethanol volume concentration aqueous solution is supplied. A small amount of hydrogen gas (100%@) containing ethanol generated from a 100% ethanol volume concentration liquid was supplied as a subflow in a small amount as a subflow. Specifically, the supply flow rate of hydrogen gas (23%@) containing ethanol generated from an aqueous solution containing a large amount of water and containing 23% of ethanol in volume was set to 80 sccm at the start of supply, and then gradually decreased to 17 sccm. Further, the supply flow rate of hydrogen gas (100%@) containing ethanol generated from a 100% ethanol volume concentration liquid was set to 0.1 sccm at the start of supply and then gradually increased to 0.3 sccm. That is, the FFO environment expressing FFO (FFO environment) controls the alcohol concentration and the water concentration in the atmosphere in the chamber 45 to be lower than the familiar environment (Run-in environment). Thus, in order to easily express FFO, it is effective to control the alcohol concentration and the water concentration to be low. In the fourteenth friction test, the second PLC film 163B (H-PLC) was used as the plate test piece 42 (see FIG. 5A). However, a plate test piece equivalent to the plate test piece used in the first to thirteenth friction tests may be used.

FIG. 26 is a graph showing the relationship between the applied load (Load) and the measurement value of the friction coefficient (Friction coefficient) in the fourteenth friction test.
In the fourteenth friction test, as shown in FIG. 26, the load was increased stepwise from 9.8N in steps of 9.8N, and was kept at 63.7N after the load reached 63.7N. When the alcohol concentration and the water concentration were controlled to be low when the load reached 63.7 N for a while, the friction coefficient was sharply decreased and FFO was developed. After that, the expression of FFO was maintained even when the load was kept at 63.7N. The friction coefficient during FFO expression was 1×10 ⁻⁴ or less. The expression time of FFO was 4 hours or more. In the first half of the FFO environment (about 2 hours in the first half), a momentary increase in the friction coefficient was repeatedly seen, but if the water content was controlled to a lower level, the second half of the FFO environment (the latter half of the FFO environment). After 2 hours, the expression of FFO was stably maintained.

From the fourteenth friction test, when nitrogen is used as the main flow, that is, when the main component of the atmosphere in the chamber 45 is nitrogen, FFO appears, and the friction coefficient is very low, and FFO is low. It was found that the expression state of was also good.
<Fifteenth and sixteenth friction tests>
27A and 27B are diagrams for explaining the test conditions of the fifteenth and sixteenth friction tests.

As shown in FIGS. 27A and 27B, in a familiar environment (Run-in environment) in the fifteenth and sixteenth friction tests, hydrogen gas is supplied at a large flow rate (4.3 slm) into the chamber 45 as a main flow. , A hydrogen gas containing water is supplied at a small flow rate as a subflow. Further, in the FFO environment (FFO environment), hydrogen gas was supplied into the chamber 45 as a main flow at a large flow rate (4.3 slm).

The 15th friction test and the 16th friction test differ in the following points. That is, in the familiar environment (Run-in environment), in the fifteenth friction test, the hydrogen gas supply flow rate containing water was set to 40 (sccm) at the start of the test and then gradually decreased to 0 (sccm). On the other hand, in the 16th friction test, the hydrogen gas supply flow rate containing water was kept at 40 (sccm). Further, in the FFO environment (FFO environment), in the fifteenth friction test, only hydrogen gas was supplied as the main flow, whereas in the sixteenth friction test, the hydrogen gas supply flow rate containing water was 40 (sccm). To 10 (sccm) and gradually supplied.

In the fifteenth and sixteenth friction tests, the first PLC film 163A (PLC) was used as the upper layer (Surface layer) of the plate test piece 42. Further, as the material for the pin test piece 44, heat-treated zirconia was used instead of heat-treated zirconia. In the pin test piece 44 formed by using the heat-treated zirconia, the crystal structure undergoes a phase transition from tetragonal to monoclinic due to heat, and the crystal lattice becomes longer, so that dissociation of hydrogen molecules and water molecules is more likely. The pin action piece 44 which is effectively expressed and is made of zirconia can further enhance the catalytic action.

28 and 29 are graphs showing the relationship between the applied load (Load) and the measurement value of the friction coefficient (Friction coefficient) in the fifteenth friction test and the sixteenth friction test, respectively.
In the fifteenth friction test, as shown in FIG. 28, the load was set to 19.6 N from the start of the test and the load magnitude was kept at 19.6 N. When the supply of hydrogen gas containing water was stopped, at the time when 45 minutes had elapsed from the start of the test, the friction coefficient sharply decreased and FFO developed. The friction coefficient repeatedly increased and decreased for a while after the start of FFO expression, but thereafter, the FFO expression state became stable. The friction coefficient during FFO development was 6×10 ⁻⁴ . The expression time of FFO was about 1 hour.

In the sixteenth friction test, as shown in FIG. 29, the load was set to 19.6 N at the start of the test, the load was increased to 29.4 N at the time when 29 minutes had elapsed from the start of the test, and at the time when another 32 minutes had elapsed. The load was increased to 39.2N and then kept at 39.2N. Even when the supply flow rate of hydrogen gas containing water was 10 (sccm), FFO became stable after the load was increased to 39.2N. The expression time of FFO was about 1 hour. The friction coefficient during FFO development was 5×10 ⁻⁴ . The expression time of FFO was about 1 hour.

From the fifteenth and sixteenth friction tests, it can be seen that FFO develops even when the atmosphere in the chamber 45 does not contain ethanol. Even if the atmosphere in the familiar environment (Run-in environment) does not include ethanol (alcohol), if the atmosphere in the FFO environment (FFO environment) contains a small amount of water, the film (first PLC film) It can be seen that the load resistance of 163A) is increased.
<17th friction test>
30A and 30B are diagrams for explaining the test conditions of the seventeenth friction test.

As shown in FIGS. 30A and 30B, in a familiar environment (Run-in environment) in the seventeenth friction test, hydrogen gas was supplied at a large flow rate (4.3 slm) into the chamber 45 as a main flow, and the ethanol volume was increased. Hydrogen gas containing ethanol (100%@) generated from a 100% concentration liquid is supplied at a minute flow rate (2 sccm) as a subflow. Further, in the FFO environment (FFO environment), nitrogen gas is supplied as a main flow into the chamber 45 at a large flow rate (4.3 slm), and hydrogen gas containing ethanol (100%@100%@ generated from a 100% ethanol volume concentration liquid) is supplied. ) Is supplied at a minute flow rate (1 sccm) as a sub-flow. In the seventeenth friction test, the first PLC film 163A (PLC) was used as the upper layer (Surface layer) of the plate test piece 42.

FIG. 31 is a graph showing the relationship between the applied load (Load) and the measurement value of the friction coefficient (Friction coefficient) in the seventeenth friction test.
In the seventeenth friction test, as shown in FIG. 31, the load was maintained at 19.6 N from the start of the test for 40 minutes, but thereafter, the load was gradually increased from 19.6 N in steps of 9.8 N. After the load reached 63.7N, it was kept at 63.7N. Before and after the load reached about 50 N, the friction coefficient decreased sharply and FFO was developed. After that, a large up-and-down movement with a large coefficient of friction was observed, but after the load reached 63.7 N, the expression of FFO was stably maintained. The friction coefficient during expression of FFO was approximately 1×10 ⁻⁴ or less. The expression time of FFO was about 1 hour.

From the seventeenth friction test, it is found that FFO is well expressed even when the atmosphere in the chamber 45 does not contain water (H ₂ O), that is, when ethanol is used as the hydroxyl group-containing compound. .. Although ethanol was used as the alcohol in the seventeenth friction test, it is presumed that similar results can be obtained by using other alcohols such as methanol, 1-propanol, and 2-propanol.

Next, the eighteenth to twentieth friction tests will be described. In the 18th to 20th friction tests, the upper layer (Surface layer) of the plate test piece 42 was changed.
<Eighteenth friction test>
As the upper layer (Surface layer) of the plate test piece 42, the third PLC film 163C (O-PLC) is adopted. Regardless of whether it is a familiar environment (Run-in environment) or FFO environment (FFO environment), hydrogen gas is supplied at a large flow rate (4.3 slm) as a main flow into the chamber 45 and generated from a 100% ethanol volume concentration liquid. Hydrogen gas containing ethanol (100%@) and hydrogen gas containing water were supplied at a small flow rate (40 sccm and 10 sccm, respectively).
<19th friction test>
As the upper layer (Surface layer) of the plate test piece 42, the first PLC film 163A (PLC) is adopted. Regardless of whether it is a familiar environment (Run-in environment) or FFO environment (FFO environment), hydrogen gas is supplied at a large flow rate (4.3 slm) as a main flow into the chamber 45, and is generated from an aqueous solution of 23% ethanol volume concentration. Hydrogen gas containing ethanol (23%@) is supplied at a medium flow rate (180 sccm), and hydrogen gas containing ethanol (100%@) generated from a 100% ethanol volume concentration liquid is supplied at a minute flow rate (2 sccm). did.
<Twentieth friction test>
As the upper layer (Surface layer) of the plate test piece 42, the second PLC film 163B (H-PLC) is adopted. Regardless of whether it is a familiar environment (Run-in environment) or FFO environment (FFO environment), hydrogen gas is supplied at a large flow rate (4.3 slm) as a main flow into the chamber 45, and is generated from an aqueous solution of 23% ethanol volume concentration. Hydrogen gas (23%@) containing ethanol was supplied at a medium flow rate (180 sccm).

33 to 35 are graphs showing the relationship between the applied load (Load) and the measurement value of the friction coefficient (Friction coefficient) in the eighteenth to twentieth friction tests.
In the eighteenth friction test, as shown in FIG. 33, the load was increased stepwise from 19.6N in steps of 9.8N, and was kept at 63.7N after the load reached 63.7N. When the alcohol concentration and the water concentration were controlled to be low, FFO was exhibited when the load was increased from 19.6N to 29.4N, and FFO was maintained even when the load was increased to 63.7N. The initial friction coefficient of FFO at a load of 63.7 N was about 5×10 ⁻⁴ , but the friction coefficient decreased with the passage of time, and decreased to about 1×10 ⁻⁴ or less . After that, the coefficient of friction gradually increased. The expression time of FFO was 2 hours or more.

In the nineteenth friction test, as shown in FIG. 34, the load was increased stepwise from 19.6N in steps of 9.8N and kept at 63.7N after the load reached 63.7N. When the alcohol concentration and the water concentration were controlled to be low, the friction coefficient suddenly decreased and FFO was developed at the time point 23 minutes after the start of the test. After that, the load was increased stepwise in increments of 9.8N, and after the load reached 63.7N, it was kept at 63.7N. When the load was increased to 39.2N, FFO was stably expressed and even when the load was 63.7N. The coefficient of friction during the development of FFO exhibited a low value of about 1×10 ⁻⁴ or less. The expression time of FFO was 2 hours or more.

In the twentieth friction test, as shown in FIG. 35, the load was increased stepwise from 19.6N in steps of 9.8N, and was kept at 63.7N after the load reached 63.7N. When the alcohol concentration and the water concentration were controlled to be low, the friction coefficient suddenly decreased and FFO was expressed at the time point 30 minutes after the start of the test. The initial friction coefficient of FFO was about 1×10 ⁻⁴ , but the friction coefficient gradually increased with the passage of time due to the temperature drift of the friction force measurement sensor. When there was no temperature drift of the friction sensor, it was estimated that the friction coefficient of FFO was in the range of 1×10 ⁻⁴ to 4×10 ⁻⁴ . The expression time of FFO was 4 hours or more.

From the 18th to the 20th friction tests, the first PLC film 163A (PLC), the second PLC film 163B (H-PLC), and the third PLC film 163C are used as the upper layer (Surface layer) of the plate test piece 42. It can be seen that FFO is well expressed regardless of which (O-PLC) is used.
As described above, according to this embodiment, hydrogen gas containing a trace amount of alcohol and/or water is added to the sliding surface 7 including the PLC film 9 which is a film formed by applying a bias voltage by the ionization deposition method. 1. In a nitrogen gas atmosphere environment (more specifically, an environment containing no oxygen), the sliding surface 6 formed using a metal (SUJ2, palladium, etc.) or oxide ceramics (ZrO ₂ ) is set to 1. Sliding with a Hertzian contact stress of 0 GPa or more. The metal (SUJ2, palladium, etc.) or oxide ceramics (ZrO ₂ ) forming the sliding surface 6 has a catalytic property capable of dissociating and adsorbing hydrogen molecules to generate active hydrogen. As a result of sliding the PLC film 9 on the sliding surface 6, active hydrogen is present at the sliding interface due to the catalytic action of the sliding surface 6. The alcohol contained in the atmosphere of the internal space 10 is hydrolyzed by the acid catalytic action of the active hydrogen on the sliding surface 6. Thereby, FFO can be expressed. Further, since water is present, the catalytic action of the sliding surface 6 can be stabilized by this water.

As a result, the low friction coating 5 having a remarkably low friction coefficient of the order of 10 ⁻⁴ (less than 0.001) can be formed on the sliding surface 6. The low friction coating 5 stably exhibits a remarkably low friction coefficient.
Further, it is possible to reduce the friction coefficient of the sliding surface 6 without separately using a lubricant.
Further, as a result of being able to significantly reduce the friction coefficient of the sliding surface 6, it is possible to reduce the frictional force generated between the sliding surface 6 and the sliding surface 7 without using a separate lubricant. As a result, the friction loss due to the sliding of the sliding system 1 can be significantly reduced (the friction torque can be significantly reduced). Therefore, the sliding system 1 can be reduced in size and weight, and the reliability of the sliding system 1 can be improved.

The present invention can also be implemented in other forms.
For example, although the PLC film 9 contains short-chain polyacetylene-based molecules as a main component, it may also contain other hydrocarbon molecules as a main component.
Although the PLC film 9 is described as being formed by the ionization deposition method while applying a low bias voltage or a high bias in an atmosphere environment of a hydrocarbon-based gas, the PLC film 9 is formed by another method. It may be a coating film.

Further, in parallel with the sliding of the sliding surface 6 with respect to the sliding surface 7, the alcohol/water supply state of supplying alcohol and water to the internal space 10 and the supply of alcohol and water to the internal space 10 are stopped. The supply stopped state may be alternately repeated.
By stopping the supply of alcohol and water into the chamber 12, it is possible to remove the water (water) that may be a catalyst poison as described above from the atmosphere in the chamber 12. On the other hand, when the supply of alcohol and water is stopped, ethanol and water may be depleted on the sliding surface 6 (sliding interface).

By alternately repeating the alcohol/water supply state and the supply stop state, it is possible to continue supplying ethanol and water to the sliding surface 6 (sliding interface) while suppressing water from becoming a catalyst poison. ..
Further, the processing gas supplied from the inlet 32 of the processing gas introduction pipe 19 to the internal space 10 of the chamber 12 contains at least one of nitrogen gas and hydrogen gas as a main flow. Further, this processing gas contains a trace amount of at least one of alcohol and water.

That is, the main gas (at least one of nitrogen gas and hydrogen gas) may contain both alcohol and water, may contain alcohol but does not contain water, or contains water. It may not contain alcohol. Further, although alcohol has been exemplified as an example of the hydrocarbon-based substance, other hydrocarbon-based substances (for example, methane, ethane, propane, butane, acetylene, ethylene, carboxylic acid (acetic acid, formic acid, etc.)) may be used in place of the alcohol. May be adopted.

The atmosphere in the internal space 10 of the chamber 12 may be mainly composed of hydrogen gas or nitrogen gas.
In addition, various design changes can be made within the scope of the matters described in the claims.

1... Sliding system, 5... Low friction coating, 6... Sliding surface, 7... Sliding surface, 9... PLC film (amorphous carbon-based film), 10... Internal space (space)

Claims (23)

A method for producing a low friction coating, comprising:
A sliding surface formed by using a metal or ceramic having a catalytic property that dissociates and adsorbs hydrogen molecules in a hydrogen atmosphere environment and generates active hydrogen (H ⁺ ), and an amorphous material containing hydrocarbon molecules as a main component. the space that is the arrangement and the sliding surface comprising a carbon-based film, and a replacement step of replacing the gas atmosphere containing a hydroxyl group-containing compound and hydrogen,
Sliding said space, in a state of being and the gas atmosphere containing a hydrogen hydroxyl group-containing compound, wherein the sliding surface relative to the sliding surface, for relatively sliding the above Hertzian contact stress 1.0GPa Including the dynamic process,
A method for producing a low friction coating, wherein the low friction coating is formed on the sliding surface by the sliding step. The method for producing a low friction coating according to claim 1, wherein the gas atmosphere further contains a hydrocarbon-based substance. The method for producing a low friction coating according to claim 2, wherein the hydroxyl group-containing compound and the hydrocarbon-based substance contain alcohol. The low friction coating manufacturing method according to claim 3, wherein the alcohol includes methanol. The hydroxyl group-containing compound further contains water,
5. The low friction according to claim 4, wherein the liquid methanol and the liquid methanol include gaseous methanol and gaseous steam generated from an aqueous solution in which the volume% concentration of the liquid methanol is 6% to 15%. Coating manufacturing method. The method for manufacturing a low friction coating according to claim 3, wherein the alcohol includes ethanol. The hydroxyl group-containing compound further contains water,
7. The low friction according to claim 6, wherein the liquid ethanol and the liquid ethanol contain gaseous ethanol and gaseous steam generated from an aqueous solution having a volume% concentration of 6% to 30% with respect to the liquid water. Coating manufacturing method. The method for producing a low-friction coating according to claim 7, wherein the liquid ethanol and the liquid ethanol include gaseous ethanol and water vapor generated from an aqueous solution having a volume% concentration of 15% to 25% with respect to the water. The method for manufacturing a low friction coating according to claim 3, wherein the alcohol contains 1-propanol. The method for producing a low friction coating according to claim 3, wherein the alcohol contains 2-propanol. The method for producing a low friction coating according to claim 3, wherein the hydroxyl group-containing compound is a gaseous alcohol generated from a liquid containing 100% of the alcohol. The low friction film manufacturing method according to claim 1, wherein the hydroxyl group-containing compound contains water. The method for producing a low friction coating according to claim 1, wherein the Hertz contact stress is 1.3 GPa to 2.4 GPa. The method for producing a low friction coating according to claim 1, wherein the amorphous carbon-based film contains a short-chain polyacetylene-based molecule as a main component. 15. The amorphous carbon-based film according to claim 1, wherein the amorphous carbon-based film includes a coating film formed by an ionization deposition method while applying a bias voltage in an atmosphere environment of a hydrocarbon-based gas. Friction coating manufacturing method. The amorphous carbon-based film includes a film formed by an ionization deposition method while applying a high bias voltage in an atmosphere environment of a hydrocarbon-based gas,
The method for producing a low friction coating according to claim 15, wherein at least one of hydrogen and oxygen is added to the amorphous carbon-based film. The low friction coating manufacturing method according to claim 1, wherein the sliding member is formed using ZrO ₂ . A supply step of supplying the hydroxyl group-containing compound to the space,
The method for producing a low-friction coating according to any one of claims 1 to 17, further comprising: a supply stopping step of stopping the supply of the hydroxyl group-containing compound to the space after the start of the sliding step. In parallel with the sliding step, further comprising a step of alternately repeating a supply state of supplying the hydroxyl group-containing compound to the space and a supply stop state of stopping the supply of the hydroxyl group-containing compound to the space. 19. The low friction coating manufacturing method according to any one of 1 to 18. The hydroxyl group-containing compound further contains water,
The methanol is flowed in a gaseous state by the first carrier gas,
The water is flowed in a gaseous state by the second carrier gas,
Of the flow rate of the first carrier gas containing the gaseous methanol and the flow rate of the second carrier gas containing the gaseous water, of the flow rate of the first carrier gas containing the gaseous methanol. The low friction coating manufacturing method according to claim 4, wherein the ratio is 6% to 15%. The hydroxyl group-containing compound further contains water,
The ethanol is flowed in a gaseous state by the first carrier gas,
The water is flowed in a gaseous state by the second carrier gas,
Of the flow rate of the first carrier gas containing the gaseous ethanol and the flow rate of the second carrier gas containing the gaseous water, of the flow rate of the first carrier gas containing the gaseous ethanol. The method for producing a low friction coating according to claim 6, wherein the ratio is 6% to 30%. Of the flow rate of the first carrier gas containing the gaseous ethanol and the flow rate of the second carrier gas containing the gaseous water, of the flow rate of the first carrier gas containing the gaseous ethanol. The low friction coating manufacturing method according to claim 21, wherein the ratio is 15% to 25%. The method for producing a low friction coating according to claim 2, wherein the hydrocarbon-based material contains ethylene.