Slide structure and manufacturing method thereof

Abstract

To provide a slide structure which is suitable for industrial production without requiring a running-in process and can be adopted under a wide use environment, and a manufacturing method thereof.SOLUTION: The manufacturing method of the slide structure includes: a transfer adhesion process S1 in which a first slide element 10 on which a first hard layer 12 is formed and a silica nano particle carrier 30 having a carrier face 32 which carries the silica nano particle on a surface of the carrier base 31 in advance are prepared, a surface of the first hard layer 12 of the first slide element 10 and the carrier face 32 of the silica nano particle carrier 30 are arranged to face to each other, and the silica nano particle is transferred and adhered to the surface of the first hard layer 12 of the first slide element 10 by a friction at a predefined speed and load via a water-based lubricant to form a silica film 13; and a slide process S3 in which a second slide element 20 is prepared, the silica film 13 of the first slide element 10 and a second hard layer 22 as a slide surface of the second slide element 20 are arranged to face to each other after the transfer adhesion process S1 and then relatively slide to each other via the water-based lubricant or an oil-based lubricant.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sliding structure and a manufacturing method thereof. [Background technology]

[0002] Conventionally, techniques related to water-lubricated sliding structures have been proposed. For example, a sliding structure has been proposed that includes first and second sliding elements each having a sliding surface, and the sliding surfaces contact each other via a water layer, thereby allowing the first and second sliding elements to slide relative to each other, where each of the first and second sliding elements includes a base material and a hard layer on the surface of the base material as the sliding surface, and at least one of the hard layers of the first and second sliding elements includes a nanosilica layer carrying silica nanoparticles (see, for example, Patent Document 1, etc.).

[0003] According to this sliding structure, the surface of the nanosilica layer is covered with a water layer, and when an appropriate sliding speed and load are applied, water lubrication properties are exhibited, and the first and second sliding elements slide against each other with relatively low friction. Therefore, a sliding structure that exhibits excellent water lubrication sliding properties with a simple configuration can be provided. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 027055 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, when silica nanoparticles are supported on the sliding surface and sliding is performed, a break-in process is required between the first and second sliding elements to achieve low friction, which poses a problem for realizing industrial production.Furthermore, there is also the problem that the lubricating liquid is limited to water-based liquids, which limits the usage environment.

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a sliding structure and a manufacturing method thereof that does not require a break-in process, is suitable for industrial production, and is applicable to a wide range of usage environments. [Means for solving the problem]

[0007] The method for manufacturing a sliding structure according to the present invention is a method for manufacturing a sliding structure in which a first sliding element and a second sliding element come into contact with each other via a lubricating liquid and thereby slide relative to each other, and includes the following steps: a transfer step of preparing a first sliding element having a first hard layer formed on at least the surface of a first base material, and a silica nanoparticle carrier having a carrier surface formed by previously supporting silica nanoparticles on the surface of a carrier base material, arranging the first hard layer surface of the first sliding element and the carrier surface of the silica nanoparticle carrier so as to face each other, and rubbing them against each other at a predetermined speed and load via a water-based lubricating liquid, thereby transferring the silica nanoparticles to the first hard layer surface of the first sliding element to form a silica film; and a sliding step of preparing a second sliding element, and after the transfer step, arranging the silica film of the first sliding element and the sliding surface of the second sliding element so as to face each other, and sliding them relative to each other via a water-based lubricating liquid or an oil-based lubricating liquid.

[0008] In addition, the transfer step uses a silicon-containing body as the support base material.

[0009] The silicon-containing body is made of a glassy material.

[0010] In the transfer step, the load applied between the first sliding element and the silica nanoparticle carrier is gradually increased from an initial load until it reaches a predetermined load value.

[0011] The first hard layer is made of diamond-like carbon.

[0012] Furthermore, the sliding surface of the second sliding element is made of a second hard layer, and when the water-based lubricant is used in the sliding step, the second hard layer is made of diamond-like carbon or silicon nitride.

[0013] Furthermore, the sliding surface of the second sliding element is made of a second hard layer, and when the oil-based lubricant is used in the sliding step, the second hard layer is made of diamond-like carbon.

[0014] The sliding structure according to the present invention is a sliding structure in which a first sliding element and a second sliding element come into contact with each other via a lubricating liquid and slide relative to each other, and the first sliding element has a first hard layer formed on at least the surface of a first base material and a silica film formed by transferring and adhering silica nanoparticles to the surface of the first hard layer, and the silica film of the first sliding element and the sliding surface of the second sliding element are arranged opposite each other, and are configured to slide relative to each other via a water-based lubricating liquid or an oil-based lubricating liquid.

[0015] The sliding structure and manufacturing method thereof according to the present invention have the effect of providing a manufacturing method for a sliding structure that does not require a break-in process, is suitable for industrial production, and is applicable to a wide range of usage environments. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a flowchart showing a flow of a manufacturing method of a sliding structure according to an embodiment of the present invention. [Figure 2] FIG. 10 is a cross-sectional view schematically showing a first sliding element prepared in a transfer step. [Figure 3] FIG. 2 is a cross-sectional view schematically showing a silica nanoparticle-supported body having silica nanoparticles supported on its surface, which is prepared in a transfer step. [Figure 4] FIG. 10 is an explanatory view schematically showing how silica nanoparticles are transferred from a silicon-containing body to a first sliding element in a transfer step. [Figure 5] FIG. 10 is a cross-sectional view schematically showing a first sliding element on which a silica film has been formed by carrying out a transfer step. [Figure 6] FIG. 10 is a cross-sectional view schematically showing a second sliding element prepared in a sliding step. [Figure 7] FIG. 2 is an explanatory diagram schematically illustrating a sliding structure formed in a sliding step. [Figure 8]FIG. 2 is a perspective view schematically showing a ring test piece used as a first sliding element in Example 1. [Figure 9] 1 is a perspective view schematically showing a silica nanoparticle support using quartz glass as a support base material in Example 1. FIG. [Figure 10] FIG. 1 is an explanatory diagram schematically illustrating a state in which a transfer step is carried out using an experimental device in Example 1. [Figure 11] 1 is a graph showing the process of silica nanoparticles being transferred to a ring test piece (first sliding element) in the transfer step of Example 1. [Figure 12] 1 is an FE-SEM image of the diamond-like carbon surface of the first hard layer in the first sliding element according to Example 1. [Figure 13] 1 is an FE-SEM image of the surface of a silica film formed by transferring silica nanoparticles to a first hard layer in a first sliding element according to Example 1. [Figure 14] FIG. 2 is a perspective view schematically showing a disk test piece used as a second sliding element in Example 1. [Figure 15] FIG. 2 is an explanatory diagram schematically showing how a sliding step is carried out using an experimental device in Example 1. [Figure 16] 1 is a graph showing the results of a friction and wear test in a sliding step of Example 1. [Figure 17] 1 is a graph showing the results of a friction and wear test of Comparative Example 1. [Figure 18] FIG. 10 is an explanatory diagram schematically showing how a sliding step is carried out using an experimental device in Example 2. [Figure 19] 10 is a graph showing the process of silica nanoparticles being transferred to a ring test piece (first sliding element) in the transfer step of Example 2. [Figure 20] 10 is a graph showing the results of a friction and wear test in a sliding step of Example 2. [Figure 21] 10 is a graph showing the results of a friction and wear test of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the sliding structure and its manufacturing method according to the present invention will be described with reference to FIGS. 1 to 7 of the drawings. FIG. 1 is a flowchart showing the flow of the manufacturing method of the sliding structure according to the embodiment. FIG. 2 is a cross-sectional view schematically showing a first sliding element 10 prepared in the transfer step S1. FIG. 3 is a cross-sectional view schematically showing a silica nanoparticle support 30 prepared in the transfer step S1, in which silica nanoparticles are supported on the surface of a support base material 31. FIG. 4 is an explanatory diagram schematically showing a state in which silica nanoparticles are transferred from the silica nanoparticle support 30 to the first sliding element 10 in the transfer step S1. FIG. 5 is a cross-sectional view schematically showing the first sliding element 10 on which a silica film 13 is formed by carrying out the transfer step S1. FIG. 6 is a cross-sectional view schematically showing a second sliding element 20 prepared in the sliding step S3. FIG. 7 is an explanatory diagram schematically showing the sliding structure 1 formed in the sliding step S3.

[0018] First, in S1 (S represents a step, and the same applies to the other steps), a transfer step is performed. In the transfer step S1, the first sliding element 10 is prepared.

[0019] The first sliding element 10 has a first base material 11 and a first hard layer 12 formed on the surface of the first base material 11 .

[0020] The first base material 11 is made of steel. For example, the first base material 11 can be made of SUS440C, which is machined into a predetermined shape and quenched to a quench hardness of HRC58. Furthermore, the surface of the first base material 11 can be finished to a surface roughness of Ra0.1 or less (for example, Ra0.01) by performing a lapping process.

[0021] The first hard layer 12 is a layer formed on the surface of the first base material 11. More specifically, the first hard layer 12 is formed by applying a diamond-like carbon (hereinafter also referred to as DLC or aC:H) coating.

[0022] Furthermore, in the transfer step S1, a silica nanoparticle support 30 is prepared. As shown in FIG. 3, the silica nanoparticle support 30 has a support surface 32 in which silica nanoparticles are previously supported on the surface of a support base material 31 by atmospheric plasma or the like. A silicon-containing material can be used as the support base material 31. The silicon-containing material used as the support base material 31 is made of, for example, a glassy material. Preferably, quartz glass, enamel, or the like can be used as the glassy material.

[0023] The surface of the first hard layer 12 of the first sliding element 10 and the support surface 32 of the silica nanoparticle supporter 30 are then placed face-to-face and immersed in a water-based lubricant containing purified water as the main component, with the water-based lubricant interposed between the two surfaces. In this state, the first sliding element 10 and the silica nanoparticle supporter 30 are moved relative to each other at a predetermined speed while a load is applied between them, causing friction via the water-based lubricant. The load applied between the first sliding element 10 and the silica nanoparticle supporter 30 is gradually increased from an initial load until it reaches a predetermined load value. By performing the transfer step S1, the silica nanoparticles supported on the support surface 32 of the silica nanoparticle supporter 30 are transferred to the surface of the first hard layer 12 of the first sliding element 10, forming a silica film 13.

[0024] Next, in S2, a cleaning step is performed. In the cleaning step S2, the first sliding element 10 having the silica film 13 formed on the surface of the first hard layer 12 is ultrasonically cleaned. Acetone, for example, can be used as the cleaning liquid. Note that the cleaning step S2 is intended to remove silica nanoparticles (floating particles) that were not transferred to the surface of the first hard layer 12 in the transfer step S1, and is not an essential step in the present invention.

[0025] Finally, in S3, a sliding step is performed. In the sliding step S3, a second sliding element 20 is prepared. The second sliding element 20 is the same as the first sliding element 10 before the silica film 13 is formed in the transfer step S1.

[0026] That is, the second sliding element 20 has a second base material 21 and a second hard layer 22 formed on the surface of the second base material 21 .

[0027] The second base material 21 is made of steel. For example, the second base material 21 can be made of SUS440C, which is machined into a predetermined shape and quenched to a quench hardness of HRC58. Furthermore, by performing lapping on the second base material 21, the surface roughness can be finished to Ra0.1 or less (for example, Ra0.01).

[0028] The second hard layer 22 is a layer formed on the surface of the second base material 21. More specifically, the second hard layer 22 is formed by applying a DLC (aC:H) coating.

[0029] In the sliding step S3, the silica film 13 formed on the first hard layer 12 of the first sliding element and the surface of the second hard layer 22 of the second sliding element 20 are placed face to face and then slid relative to each other via the lubricating liquid. The lubricating liquid may be a water-based lubricating liquid or an oil-based lubricating liquid. The water-based lubricating liquid has the advantage of being environmentally friendly. On the other hand, the oil-based lubricating liquid has the advantage of being able to expect a synergistic effect of low friction due to the properties of oil, and is effective even in environments where water-based lubricating liquids cannot be used. For example, a lubricating liquid containing purified water as its main component can be used as the water-based lubricating liquid. For example, a lubricating liquid containing polyalphaolefin (e.g., PAO4) as its main component can be used as the oil-based lubricating liquid.

[0030] As described above, the manufacturing of the sliding structure 1 according to this embodiment is completed through the steps from the transfer step S1 to the sliding step S3.

[0031] <Summary of the embodiment> As is clear from the above detailed description, the manufacturing method of the sliding structure according to the present embodiment is a method for manufacturing a sliding structure 1 in which a first sliding element 10 and a second sliding element 20 come into contact with each other via a lubricating liquid and thereby slide relatively, and includes the steps of preparing a first sliding element 10 having a first hard layer 12 formed on at least the surface of a first base material 11 and a silica nanoparticle carrier 30 having a carrier surface 32 in which silica nanoparticles are previously supported on the surface of a carrier base material 31, and The method includes a transfer step S1 in which the first sliding element 10 and the supporting surface 32 of the nanoparticle support 30 are arranged opposite each other and rubbed against each other at a predetermined speed and load via a water-based lubricant, thereby transferring silica nanoparticles to the surface of the first hard layer 12 of the first sliding element 10 to form a silica film 13; and a sliding step S3 in which the second sliding element 20 is prepared, and after the transfer step S1, the silica film 13 of the first sliding element 10 and the second hard layer 22 as a sliding surface of the second sliding element 20 are arranged opposite each other and allowed to slide relative to each other via a water-based lubricant or an oil-based lubricant.

[0032] In addition, in the transfer step S1, a silicon-containing body is used as the support base material 31.

[0033] The silicon-containing body used as the support base material 31 is preferably made of a glassy material.

[0034] Furthermore, in the transfer step S1, the load applied between the first sliding element 10 and the silica nanoparticle carrier 30 is gradually increased from the initial load until it reaches a predetermined load value.

[0035] The first hard layer 12 is preferably made of diamond-like carbon.

[0036] The sliding surface of the second sliding element 20 is made of a second hard layer 22, and when a water-based lubricant is used in the sliding step S3, the second hard layer 22 is preferably made of diamond-like carbon or silicon nitride.

[0037] Furthermore, the sliding surface of the second sliding element 20 is made of a second hard layer 22, and when an oil-based lubricant is used in the sliding step S3, the second hard layer 22 is preferably made of diamond-like carbon.

[0038] The sliding structure 1 according to this embodiment is a sliding structure in which a first sliding element 10 and a second sliding element 20 come into contact with each other via a lubricating liquid and thereby slide relative to each other. The first sliding element 10 has a first hard layer 12 formed on at least the surface of a first base material 11 and a silica film 13 formed by transferring silica nanoparticles to the surface of the first hard layer 12. The silica film 13 of the first sliding element 10 and the sliding surface of the second sliding element 20 are arranged opposite each other and are configured to slide relative to each other via a water-based lubricating liquid or an oil-based lubricating liquid.

[0039] The sliding structure and manufacturing method thereof according to this embodiment have the advantage of being able to provide a sliding structure 1 and a manufacturing method thereof that does not require a break-in process, is suitable for industrial production, and is applicable to a wide range of usage environments. [Example]

[0040] Hereinafter, examples of the sliding structure and manufacturing method thereof according to this embodiment will be described with reference to Figs. 8 to 21. Fig. 8 is a perspective view schematically showing a ring test piece used as the first sliding element 10 in Example 1. Fig. 9 is a perspective view schematically showing a silica nanoparticle carrier 30 in Example 1, in which silica glass is used as the carrier base material 31. Fig. 10 is an explanatory view schematically showing the manner in which the transfer step S1 is carried out using an experimental apparatus 100 in Example 1. Fig. 11 is a graph showing the process in which silica nanoparticles are transferred to the ring test piece (first sliding element 10) in the transfer step S1 in Example 1.

[0041] FIG. 12 is an FE-SEM image of the diamond-like carbon surface of the first hard layer 12 in the first sliding element 10 according to Example 1. FIG. 13 is an FE-SEM image of the surface of the silica film 13 formed by transferring silica nanoparticles to the first hard layer 12 in the first sliding element 10 according to Example 1. FIG. 14 is a perspective view schematically showing a disk test piece used as the second sliding element 20 in Example 1. FIG. 15 is an explanatory diagram schematically showing how the sliding step S3 is performed using the experimental apparatus 100 in Example 1. FIG. 16 is a graph showing the results of a friction and wear test in the sliding step S3 in Example 1. FIG. 17 is a graph showing the results of a friction and wear test in Comparative Example 1. FIG. 18 is an explanatory diagram schematically showing how the sliding step S3 is performed using the experimental apparatus 100 in Example 2. FIG. 19 is a graph showing a process in which silica nanoparticles are transferred to the ring test piece (first sliding element 10) in the transfer step S1 in Example 2. 20 is a graph showing the results of the friction and wear test in the sliding step S3 of Example 2. FIG.

[0042] Example 1 First, in the transfer step S1, a ring test piece was prepared as the first sliding element 10, in which a DLC (aC:H) coating was applied to a first base material 11 as a first hard layer 12. The ring test piece had a cylindrical shape of φ16 × φ11.4 × 7 [mm].

[0043] Furthermore, silica nanoparticle support 30 was prepared by previously supporting silica nanoparticles on the surface of quartz glass as support base material 31 using atmospheric plasma or the like. The quartz glass was in the form of a square plate measuring 20 × 20 × 4 mm.

[0044] Furthermore, an EFM-3-H friction and wear testing device for tribology evaluation manufactured by A&D was prepared as the experimental device 100. The experimental device 100 is configured to include a bottomed cylinder 101, a rotation mechanism 102 that rotates the bottomed cylinder 101 around a vertical axis, a support mechanism 103 that supports a ring test piece as the first sliding element 10 from above, and a load cell (not shown). The support mechanism 103 is configured to include an upper member 104, a lower member 105, and a ball bearing 106 provided between the upper member 104 and the lower member 105.

[0045] 10, the silica nanoparticle carrier 30 (quartz glass) was placed on the inner bottom surface of the bottomed cylinder 101 of the experimental apparatus 100 with the carrier surface 32 facing upward. Furthermore, the first sliding element 10 was placed on the carrier surface 32 of the silica nanoparticle carrier 30 with the first hard layer 12 facing downward.

[0046] In this state, the upper part of the first sliding element 10 was supported by the support mechanism 103, and purified water was poured into the inner periphery of the bottomed cylinder 101. The first sliding element 10 and the silica nanoparticle carrier 30, which were arranged facing each other with the surface of the first hard layer 12 and the carrier surface 32 overlapping each other, were entirely immersed in purified water as a water-based lubricating liquid.

[0047] Then, a load was applied to the first sliding element 10 and the silica nanoparticle carrier 30 from above the experimental apparatus 100 via a load cell and a support mechanism 103, while the bottomed cylinder 101 was rotated by a rotation mechanism 102 at the bottom of the experimental apparatus 100. At this time, the first sliding element 10 (ring test piece) was stationary with a recess provided in the circumferential direction engaging with a lower member 105 of the support mechanism 103. Meanwhile, as the rotation mechanism 102 rotates, the silica nanoparticle carrier 30 (disk test piece) rotates integrally with the bottomed cylinder 101. In other words, slippage occurs between the first sliding element 10 (ring test piece) and the silica nanoparticle carrier 30 (disk test piece).

[0048] Friction with a limit load of 5000 N is applied by the lower rotation mechanism 102, and the maximum shaft rotation speed is 3350 rpm. The friction force is detected as friction torque via the upper arm 108 by a load cell with a rated load of 100 N. Because the support mechanism 103 has a structure with a ball bearing 106 between the upper member 104 and the lower member 105, the first sliding element 10 (ring test piece) and the silica nanoparticle carrier 30 (disk test piece) come into surface contact immediately after the start of the test. The sliding surface is always kept immersed, but the purified water is not replaced from the start to the end of the test.

[0049] FIG. 11 is a graph showing the experimental results of the transfer step S1, with the horizontal axis representing time, the right vertical axis representing load, and the left vertical axis representing friction coefficient. In the transfer step S1, as shown in the graph in FIG. 11, the load applied to the first sliding element 10 (ring test piece) and the silica nanoparticle carrier 30 (disk test piece) was gradually increased from the initial load until a predetermined load value was reached. This predetermined value was the load at which the transfer of the silica nanoparticles to the first hard layer 12 was completed, and was a value determined experimentally in advance. The specific test conditions were a sliding speed of 0.3 m / s, a vertical load of 50 N for 60 seconds, followed by a load increase from 100 N to 500 N in 100 N increments for 30 seconds, and then the test was terminated 300 seconds after reaching 500 N.

[0050] The photograph in Fig. 12 shows that before the transfer step S1, no silica nanoparticles are present on the diamond-like carbon surface that constitutes the first hard layer 12 of the first sliding element 10. On the other hand, the photograph in Fig. 13 shows that after the transfer step S1, a large number of silica nanoparticles have been transferred to the diamond-like carbon surface that constitutes the first hard layer 12 of the first sliding element 10.

[0051] Next, in the cleaning step S2, the first sliding element 10 having the silica film 13 formed on the first hard layer 12 was taken out of the experimental apparatus 100 and subjected to ultrasonic cleaning with acetone for 5 minutes. This removes silica nanoparticles (floating particles) that were not transferred to the first hard layer 12.

[0052] Next, in the sliding step S3, a disk test piece having a second hard layer 22 formed by applying a DLC (aC:H) coating to a second base material 21 was prepared as the second sliding element 20. The disk test piece was a square plate measuring 20 × 20 × 4 mm.

[0053] Next, using the experimental apparatus 100 again, the second sliding element 20 was placed on the inner bottom surface of the bottomed cylinder 101 with the second hard layer 22 facing upward. Furthermore, the first sliding element 10 was placed on the second hard layer 22 of the second sliding element 20 with the silica film 13 facing downward.

[0054] In this state, the upper surface of the first sliding element 10 was supported by the support mechanism 103, and the silica film 13, which was the sliding surface on the first sliding element 10 side, and the second hard layer 22, which was the sliding surface on the second sliding element 20 side, were overlapped and arranged facing each other, and a predetermined amount (60 μL) of oil-based lubricating liquid containing PAO4 (polyalphaolefin) as a main component was added between the two sliding surfaces.

[0055] Then, a load was applied to the first sliding element 10 and the second sliding element 20 from above the experimental apparatus 100 via a load cell and a support mechanism 103, while the bottomed cylindrical body 101 was rotated by a rotation mechanism 102 at the bottom of the experimental apparatus 100. At this time, the first sliding element 10 (ring test piece) was stationary with a recess provided in the circumferential direction engaged with a lower member 105 of the support mechanism 103. Meanwhile, as the rotation mechanism 102 rotates, the second sliding element 20 (disk test piece) rotates integrally with the bottomed cylindrical body 101. In other words, sliding occurs between the first sliding element 10 (ring test piece) and the second sliding element 20 (disk test piece). The sliding speed of the first sliding element 10 (ring test piece) is the speed at the mid-radius position between the inner and outer peripheries of the ring test piece, and is determined by the rotation speed of the rotation mechanism 102.

[0056] Figure 16 is a graph showing the experimental results of the sliding step S3, with the horizontal axis representing time, the right vertical axis representing the friction coefficient, and the left vertical axis representing the sliding speed. While a load of 500 N was continuously applied, the sliding speed (unit: m / s) was varied from 0.3 to 0.1, 0.05, 0.01, 0.05, 0.1, and 0.3 every 300 seconds. Despite the change in sliding speed, the friction coefficient exhibited ultra-low or low friction values ​​of 0.0095 to 0.055. In other words, excellent low-friction performance was confirmed under the following conditions: first hard layer 12: diamond-like carbon (with aC:H silica film), second hard layer 22: diamond-like carbon (without aC:H silica film), and lubricant: oil-based lubricant (PAO4).

[0057] (Comparative Example 1) In Comparative Example 1, the transfer step S1 was not performed, that is, a ring test piece was prepared as the first sliding element 10 having a first hard layer 12 made of diamond-like carbon (no aC:H silica film) to which silica nanoparticles had not been transferred, and a disk test piece was prepared as the second sliding element 20 having a second hard layer 22 made of silicon nitride (no silica film). As in the Examples, the upper part of the first sliding element 10 was supported by the support mechanism 103, and the silica film 13, which was the sliding surface on the first sliding element 10 side, and the second hard layer 22, which was the sliding surface on the second sliding element 20 side, were overlapped and arranged facing each other, and a small amount (60 μL) of an oil-based lubricant mainly composed of PAO4 (polyalphaolefin) was added between the two sliding surfaces.

[0058] Then, a load was applied to the first sliding element 10 and the second sliding element 20 from above the experimental device 100 via the load cell and the support mechanism 103, while the bottomed cylinder 101 was rotated by the rotation mechanism 102 at the bottom of the experimental device 100.

[0059] In Comparative Example 1, as can be seen from the graph in FIG. 17, when the sliding speed was changed between approximately 500 seconds and approximately 2000 seconds while a load of 500 N was continuously applied, the friction coefficient exceeded 0.1 after approximately 1300 seconds had passed, indicating that low friction could not be maintained.

[0060] Example 2 In Example 2, a friction and wear test was performed using a water-based lubricant (purified water) in the sliding step S3. Example 2 differs from Example 1 in that the lubricant used in the sliding step S3 was changed from an oil-based lubricant to a water-based lubricant, and that the second hard layer 22 was changed from diamond-like carbon (without aC:H silica film) to silicon nitride. In Example 1, a small amount of oil-based lubricant was added between the sliding surfaces of the first sliding element 10 and the second sliding element 20. In Example 2, as shown in FIG. 18, water-based lubricant (purified water) was poured into the inner periphery of the bottomed cylinder 101 to a height equal to or higher than the top position of the first sliding element 10. The first sliding element 10 and the second sliding element 20, which were arranged facing each other with the silica film 13 on the sliding surface of the first sliding element 10 and the second hard layer 22 on the sliding surface of the second sliding element 20 overlapping, were entirely immersed in the water-based lubricant.

[0061] FIG. 19 is a graph showing the experimental results of the transfer step S1, with the horizontal axis representing time, the right vertical axis representing load, and the left vertical axis representing friction coefficient. In the transfer step S1, as shown in the graph in FIG. 19, the load applied to the first sliding element 10 (ring test piece) and the silica nanoparticle carrier 30 (disk test piece) was gradually increased from the initial load until a predetermined load value was reached. This predetermined value was the load at which the transfer of the silica nanoparticles to the first hard layer 12 was completed, and was a value experimentally determined in advance. The specific test conditions were a sliding speed of 0.3 m / s, a vertical load of 50 N for 60 seconds, followed by a load increase from 100 N to 500 N in 100 N increments for 30 seconds, and then the test was terminated 300 seconds after reaching 500 N. After the transfer step S1 and before the experiment in the sliding step S3, the first hard layer 12 (aC:H) of the first sliding element 10 (ring test piece) was subjected to ultrasonic cleaning with acetone for 5 minutes in the cleaning step S2.

[0062] In Example 2, in the sliding step S3, a ring test piece having a first hard layer 12 made of diamond-like carbon (with an aC:H silica film) to which silica had been transferred was used as the first sliding element 10, and a disk test piece having a second hard layer 22 made of silicon nitride (without a silica film) was used as the second sliding element 20. Figure 20 is a graph showing the experimental results of the sliding step S3, with the horizontal axis representing time, the right vertical axis representing the friction coefficient, and the left vertical axis representing the sliding velocity. When the sliding velocity (unit: m / s) was changed to 0.3, 0.1, 0.05, 0.01, 0.05, 0.1, and 0.3 every 300 seconds, the friction coefficient at the end of the test at a sliding velocity of 0.3 m / s was 0.0095, an extremely low friction. In other words, excellent low-friction performance was confirmed when the lubricant was a water-based lubricant (purified water).

[0063] (Comparative Example 2) In Comparative Example 2, the transfer step S1 was not performed, that is, a ring test piece was prepared as the first sliding element 10 having a first hard layer 12 made of diamond-like carbon (no aC:H silica film) to which silica nanoparticles had not been transferred, and a disk test piece was prepared as the second sliding element 20 having a second hard layer 22 made of silicon nitride (no silica film). In addition, similar to Example 2, a water-based lubricant (purified water) was poured into the inner periphery of the bottomed cylinder 101 to a height equal to or higher than the top position of the first sliding element 10, and the first sliding element 10 and the second sliding element 20, which were arranged facing each other with the silica film 13, which is the sliding surface on the first sliding element 10 side, and the second hard layer 22, which is the sliding surface on the second sliding element 20 side, overlapping each other, were immersed entirely in the water-based lubricant.

[0064] Then, a load was applied to the first sliding element 10 and the second sliding element 20 from above the experimental device 100 via the load cell and the support mechanism 103, while the bottomed cylinder 101 was rotated by the rotation mechanism 102 at the bottom of the experimental device 100.

[0065] In Comparative Example 2, when the sliding speed (unit [m / s]) was changed to 0.3, 0.1, 0.05, 0.01, 0.05, 0.1, and 0.3 every 300 seconds, the friction coefficient at a sliding speed of 0.3 [m / s] at the end of the test was 0.017. The friction coefficient in Comparative Example 2 was a larger value than in Example 2, demonstrating the effectiveness of Example 2.

[0066] <Modification> The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit and scope of the present invention. For example, in the above examples, a ring test piece and a disk test piece are used as the first sliding element 10 and the second sliding element 20, respectively. However, the present invention is not limited to this. For example, the first sliding element 10 and the second sliding element 20 may be configured to use a large-diameter cylindrical member and a small-diameter cylindrical member, with lubricated sliding between the inner circumferential surface of the large-diameter cylindrical member and the outer circumferential surface of the small-diameter cylindrical member. Alternatively, the first sliding element 10 and the second sliding element 20 may be configured to use a pair of flat or block-shaped members, both having flat sliding surfaces, with lubricated sliding between the flat sliding surfaces. Furthermore, although an example in which the second sliding element 20 includes a second hard layer 22 on the surface of the second base material 21 has been shown, the present invention is not limited to this. For example, the second base material 21 may be made of steel such as SUS440C or SUJ2, or hard resin such as acrylic resin, polycarbonate resin, or ABS resin, and the surface of the second base material 21 itself may be used as the sliding surface of the second sliding element 20 without providing the second hard layer 22. [Industrial Applicability]

[0067] The present invention can be used in any sliding structure or device including a sliding structure that includes first and second sliding elements each having a sliding surface, where the sliding surfaces are in contact with each other via a lubricating liquid layer, allowing the first and second sliding elements to slide relative to each other. For example, the present invention can be used in various fields, such as sliding structures in seals for fluid equipment such as piston rings and cylinders, sliding bearings, and mechanical seals for rotating shafts, as well as in vehicles, machine tools, and other devices that use such sliding structures. [Explanation of symbols]

[0068] 1 Sliding structure 10 First sliding element 11 First base material 12 1st hard layer 13 Silica membrane 20 second sliding element 21 2nd base material 22 Second hard layer 30 Silica nanoparticle support 31 Support base material (quartz glass) 32 Support surface S1 Transfer process S2 cleaning process S3 Sliding process

Claims

1. A method for manufacturing a sliding structure in which a first sliding element and a second sliding element slide relatively by contacting each other via a lubricating liquid, comprising: a transfer step of preparing the first sliding element having a first hard layer formed on at least the surface of a first base material and a silica nanoparticle carrier having a carrier surface on which silica nanoparticles have been previously supported on the surface of a carrier base material, arranging the first hard layer surface of the first sliding element and the carrier surface of the silica nanoparticle carrier so as to face each other, and causing friction between them at a predetermined speed and load via a water-based lubricant, thereby transferring the silica nanoparticles to the first hard layer surface of the first sliding element and forming a silica film; a sliding step of preparing the second sliding element, and after the transferring step, disposing the silica film of the first sliding element and the sliding surface of the second sliding element so as to face each other, and sliding the silica film and the sliding surface of the second sliding element relative to each other via a water-based lubricating liquid or an oil-based lubricating liquid; A method for manufacturing a sliding structure comprising:

2. The method for manufacturing a slide structure according to claim 1 , wherein the transfer step uses a silicon-containing body as the carrier base material.

3. The method for manufacturing a sliding structure according to claim 2 , wherein the silicon-containing body used as the carrier base material is made of a glassy material.

4. The method for manufacturing a sliding structure according to claim 1 , wherein the transfer step gradually increases a load applied between the first sliding element and the silica nanoparticle carrier from an initial load until the load reaches a predetermined value.

5. The method for manufacturing a sliding structure according to claim 1 , wherein the first hard layer is made of diamond-like carbon.

6. the sliding surface of the second sliding element is made of a second hard layer, 6. The method for manufacturing a sliding structure according to claim 5, wherein when the water-based lubricant is used in the sliding step, the second hard layer is made of diamond-like carbon or silicon nitride.

7. the sliding surface of the second sliding element is made of a second hard layer, 6. The method for manufacturing a sliding structure according to claim 5, wherein when the oil-based lubricant is used in the sliding step, the second hard layer is made of diamond-like carbon.

8. A sliding structure in which a first sliding element and a second sliding element slide relatively by contacting each other via a lubricating liquid, the first sliding element has a first hard layer formed on at least a surface of a first base material and a silica film formed by transferring and adhering silica nanoparticles to the surface of the first hard layer, A sliding structure in which the silica film of the first sliding element and the sliding surface of the second sliding element are arranged opposite to each other and configured to slide relatively via a water-based lubricating liquid or an oil-based lubricating liquid.

Images