Method for manufacturing a sliding member and sliding member

Abstract

This disclosure aims to manufacture a sliding member that can exhibit wear resistance even when the operating temperature drops to a low temperature range of approximately 300°C to 600°C. The purpose is to achieve this. [Solution] The present disclosure is a method for manufacturing a sliding member for operation in a high-temperature dry environment of 300°C or higher in the presence of oxygen, comprising: projecting a projectile onto a substrate surface by shot peening to form a protective lubricating layer on the substrate surface containing metal components derived from the projectile and substrate components; the material of the projectile is selected from metal elements or metal compounds that can become metal oxides with a melting point of 300 to 1200°C by oxidation.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a sliding member and a sliding member.

Background Art

[0002] In high-temperature operating machines such as gas turbines, aero engines, and turbochargers, vibrations occur due to rotation and fluid flow during operation. Wear due to vibration occurs at locations where parts are in contact with each other (sliding members).

[0003] Under such circumstances, in order to improve wear resistance in a high-temperature environment, sliding members are subjected to optimization of material composition, hardening treatment, thermal spraying coating formation, etc.

[0004] In Patent Document 1, the composition of a heat-resistant Co-based alloy is optimized for the purpose of improving work hardening characteristics. Further, in Patent Document 1, a pre-hardened layer is formed on a Co-based alloy with a novel element composition by shot peening treatment to prevent wear damage of high-temperature members for gas turbines.

[0005] Patent Document 2 discloses a technique for forming a thermal spraying coating to improve the wear resistance of parts such as fan compressor blades of a gas turbine engine. For the formation of the thermal spraying coating, a thermal spraying material in which a low-melting-point metal such as Cu or Ag is applied to the surface of molybdenum disulfide (MoS2) particles having excellent wear resistance is used. In the thermal spraying coating, MoS2 is uniformly present.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] To suppress vibrations and prevent cooling air leakage, seal pins are inserted at the base of the turbine blades. A small amount of reciprocating slip occurs repeatedly between the seal pin and the turbine blade. This causes fretting wear on the seal pin.

[0008] In actual gas turbines, excessive wear of the seal pin can occur as the temperature around the seal pin decreases.

[0009] While the wear resistance of sliding members has been demonstrated in conventional technologies such as those described in Patent Documents 1 and 2 at high temperatures of around 700°C, wear resistance in temperatures below 700°C has not been verified. Therefore, wear resistance across a wide temperature range may be insufficient, and corresponding wear reduction measures are necessary.

[0010] This disclosure has been made in view of these circumstances and aims to provide a method for manufacturing a sliding member and a sliding member that can reduce wear in a temperature range of 700°C or less. [Means for solving the problem]

[0011] To solve the above problems, the manufacturing method of the sliding member and the sliding member of this disclosure employ the following means.

[0012] This disclosure provides a method for manufacturing a sliding member to operate in a high-temperature dry environment of 300°C or higher in the presence of oxygen, wherein a projectile is projected onto a substrate surface by shot peening to form a protective lubricating layer on the substrate surface containing metal components derived from the projectile and substrate components, and the material of the projectile is selected from metal elements or metal compounds that can become metal oxides with a melting point of 300 to 1200°C upon oxidation.

[0013] This disclosure provides a sliding member for operation in a high-temperature dry environment of 300°C or higher in the presence of oxygen, comprising a base material and a protective lubricating layer covering the surface of the base material, wherein the protective lubricating layer contains elements derived from metal elements or metal compounds that can become metal oxides with a melting point of 300 to 1200°C by oxidation, and components derived from the base material.

[0014] This disclosure provides a sliding member for operation in a high-temperature dry environment of 300°C or higher in the presence of oxygen, comprising a base material and a protective lubricating oxide layer covering the surface of the base material, wherein the protective lubricating oxide layer contains a metal oxide with a melting point of 300 to 1200°C and components derived from the base material. [Effects of the Invention]

[0015] It is possible to manufacture sliding components that can exhibit wear resistance even when the operating temperature drops to a temperature range of 700°C or lower. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic cross-sectional view of the sliding member. [Figure 2] This is a schematic diagram of a gas turbine blade. [Figure 3] This is a schematic cross-sectional diagram illustrating the sliding motion between the seal pin and the seal pin groove. [Figure 4] This is a cross-sectional photograph of a test specimen in which Sn was used to form a protective lubricating layer. [Figure 5] This is a cross-sectional photograph of a test specimen in which MoS2 was used to form a protective lubricating layer. [Figure 6] This chart shows the results of the hardness measurement for each test specimen. [Figure 7] This graph shows the results of a fretting abrasion test (at 300°C) on a test specimen using a Ni-based heat-resistant alloy as the base material. [Figure 8] This graph shows the results of a fretting abrasion test (at 300°C) on a test specimen using a Co-based heat-resistant alloy as the base material. [Figure 9] These are cross-sectional images of each test specimen taken with a scanning electron microscope. [Figure 10] It is a chart showing the elemental analysis results of the surface layer of the test piece after sliding.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, a manufacturing method of a sliding member and an embodiment of the sliding member according to the present disclosure will be described with reference to the drawings.

[0018] [Sliding member] Fig. 1 shows a schematic cross-sectional view of the sliding member. The sliding member 1 includes a base material 2 and a protective lubricating layer 3 that covers the surface of the base material (sliding surface).

[0019] The material of the base material 2 may be a nickel-based alloy, a cobalt-based alloy, stainless steel, or the like.

[0020] The average hardness of the surface layer of the base material is preferably 1.1 times or more higher than the average hardness of the inside of the base material. The "surface layer" refers to a region with a maximum depth of 500 μm from the outermost surface. The "average hardness" refers to the average value of 5 to 10 hardness points in the surface layer of the base material measured by pressing an indenter into the cross-section of the base material.

[0021] The protective lubricating layer 3 contains components (metal elements) derived from the material of the base material 2 and components derived from the projectile used when forming the protective lubricating layer 3. The projectile contains a metal element or a metal compound. Elements derived from the metal element or the metal compound can become metal oxides with a melting point of 300 to 1200 °C by oxidation. The melting point of the metal oxide is higher than the upper limit of the operating temperature of the sliding member 1.

[0022] The metal element or the metal compound may be any of Sn, Bi, Mo, Mn, and MoS2. The metal oxide formed by oxidizing the metal element or the metal compound may be, for example, MnO2 (melting point 535 °C), MoO3 (melting point 795 °C), Bi2O3 (melting point 820 °C), Mn2O3 (melting point 1080 °C), SnO2 (melting point 1127 °C). Note that MnO2 (melting point 535 °C) changes to Mn2O3 (melting point 1080 °C) around 590 °C.

[0023] The sliding member 1 is suitable for use in high-temperature dry environments of 300°C or higher. A high-temperature dry environment is one in which oxygen is present. A "dry environment" is an environment in which the sliding member operates without the intervention of a fluid such as lubricant.

[0024] When the sliding member 1 operates in a high-temperature, dry environment, the metal elements or metal compounds contained in the protective lubrication layer 3 are oxidized by the surrounding oxygen. As a result, the protective lubrication layer 3 becomes a protective lubrication oxide layer.

[0025] The sliding member 1 may be configured for use in the sliding parts of gas turbines, aircraft engines, and turbochargers. The upper limit of the operating temperature of the sliding parts of gas turbines, aircraft engines, and turbochargers is 300°C or higher.

[0026] As a specific example, we will describe the case in which the sliding member 1 according to this embodiment is applied to a seal pin that is placed in contact between adjacent gas turbine blades.

[0027] Figure 2 shows a schematic diagram of a gas turbine blade. The gas turbine rotor blade 10 comprises a blade section 11, a platform 12, and a blade root section 13. The blade root section 13 is embedded in the rotor (not shown) of the gas turbine rotor blade 10. The platform 12 is integrally formed with the blade root section 13.

[0028] The blade section 11 is provided to extend along the radial direction of the rotor and has a base end 14 fixed to the platform 12 and a tip end 15 located on the opposite side from the base end 14 in the blade height direction (radial direction of the rotor).

[0029] The wing section 11 has a leading edge 16 and a trailing edge 17 from the base 14 to the tip 15. The wing surface of the wing section 11 includes a pressure surface (ventral surface, not shown) and a negative pressure surface (back surface) 18 that extend along the wing height direction (radial direction) between the base 14 and the tip 15.

[0030] Platform 12 has a groove 19 that is recessed from the side facing the trailing edge 17 toward the leading edge 16 and extends in the circumferential direction of the rotor. Platform 12 has a seal pin groove 20 in which a seal pin (not shown) is positioned to seal the gap between the platform 12 of other adjacent rotor blades in the circumferential direction. In Figure 2, the seal pin groove 20 is formed on the end face 22 on the negative pressure side (back side) of platform 12.

[0031] Figure 3 is a schematic cross-sectional view illustrating the sliding motion between the seal pin 21 and the seal pin groove 20. The seal pin 21 is a cylindrical member. The seal pin 21 is in contact with the seal pin groove 20, and minute reciprocating sliding motion occurs repeatedly between the seal pin 21 and the seal pin groove 20.

[0032] The seal pin 21, positioned between adjacent rotor blades and in contact with them, functions as a sealing structure that suppresses the flow of gas between the space on the blade root side 13 and the space on the blade side 11. This prevents the leakage of combustion gases. In addition, the seal pin 21 functions as a damper pin that dampens the vibration of the rotor blade through the frictional force between the seal pin 21 and the seal pin groove 20.

[0033] No fluid, such as lubricating oil, is present between the seal pin 21 and the seal pin groove 20. The area around the seal pin 21 is a high-temperature gas atmosphere containing oxygen.

[0034] In a high-temperature dry environment of 300°C or higher where oxygen is present, when the seal pin 21 is activated, the metal elements or elements derived from metal compounds contained in the protective lubrication layer 3 are oxidized by the surrounding oxygen. As a result of this oxide derived from the protective lubrication layer 3 mixing with oxide derived from the substrate, a protective lubrication oxide layer 4 is formed on the sliding surface.

[0035] [Manufacturing method for sliding members] In the manufacturing method of the sliding member according to this embodiment, a projectile is projected onto the substrate surface (the sliding surface of the sliding member) by shot peening to form a protective lubricating layer on the substrate surface. The substrate surface may be pre-treated before forming the protective lubricating layer.

[0036] (Formation of a protective lubricating layer) The material for the abrasive is selected from metal elements or metal compounds that can be oxidized to form metal oxides with melting points of 300 to 1200°C (they can be sources of metal oxides). The material for the abrasive may be selected from the group consisting of Sn, Bi, Mo, Mn, and MoS2.

[0037] The material of the abrasive material should be selected such that the melting point of the metal oxide formed by the oxidation of the material does not fall below the upper limit of the operating temperature of the sliding member. For example, if the upper limit of the operating temperature (ambient temperature) of the sliding member is 300°C, the material of the abrasive material can be selected from Sn, Bi, Mo, Mn, and MoS2. For example, if the upper limit of the operating temperature (ambient temperature) of the sliding member is 600°C, the material of the abrasive material can be selected from Sn, Bi, Mo, and MoS2. If the upper limit of the operating temperature (ambient temperature) of the sliding member is 900°C, it is preferable to use Mn or Sn as the material of the abrasive material.

[0038] The spray pressure of the abrasive material is between 0.6 MPa and 2.0 MPa. The sprayed abrasive material adheres to the substrate surface and forms a protective coating (protective lubricating layer) that covers the substrate surface.

[0039] (Pre-processing) The pretreatment is performed by shot peening. The hard particles have a hardness equal to or greater than that of the substrate. The hard particles may be high-speed tool steel or the like. The average particle size of the hard particles may be between 0.05 mm and 0.35 mm.

[0040] The hard particles are sprayed at a spray pressure of 0.1 MPa to 0.5 MPa and impacted onto the substrate surface. The spraying can be carried out using an existing shot peening apparatus. By spraying the hard particles, the hardness of the substrate surface can be improved. In the pretreatment, it is preferable to increase the average hardness of the substrate surface by 1.1 times or more than the average hardness of the substrate material itself.

[0041] [Examples] (Preparation of test specimens) According to the above embodiment, the substrate surface was pre-treated, and then a protective lubricating layer was formed on the pre-treated substrate surface by shot peening to obtain a test specimen.

[0042] Ni-based heat-resistant alloy (Inconel-X750) and Co-based heat-resistant alloy were used as the base materials.

[0043] The pretreatment conditions were the same for all test specimens.

[0044] Sn or MoS2 was used as the projection material for forming the protective lubrication layer.

[0045] The Ni-based and Co-based heat-resistant alloys used as substrates differ in color from the MoS2 and Sn used as abrasive materials. The formation of a protective lubricating layer on the substrate surface was visually confirmed.

[0046] (Composition of the protective lubricating layer) Cross-sectional samples of test specimens were prepared using Inconel-X750 (Ni-based heat-resistant alloy) as the substrate. Elemental analysis was performed on each cross-sectional sample using a scanning electron microscope.

[0047] Figure 4 shows the elemental analysis results of a test specimen using Sn. (a) is a secondary electron image, (b) is an analysis image of Ni, (c) is an analysis image of Sn, and (d) is an analysis image of O. In the test specimen using Sn as the projection material, the presence of Ni, Sn, and O was confirmed on the substrate surface. According to Figure 4(c), the concentration of Sn did not change in a gradient from the outermost surface to the interior of the substrate (depth direction), but rather a variation in density was observed in the in-plane direction of the substrate surface. From this, it is thought that Sn did not diffuse into the substrate, but rather was stirred and mixed with Ni during the shot peening process.

[0048] Figure 5 shows the elemental analysis results of a test specimen using MoS2. (a) is a secondary electron image, (b) is an analysis image of Ni, (c) is an analysis image of Mo, (d) is an analysis image of S, and (e) is an analysis image of O. In the test specimen using MoS2 as the projection material, the presence of Ni, Mo, S, and O was confirmed on the substrate surface. According to Figure 5, Mo and S are attached to the surface layer of the substrate (Ni).

[0049] The components (Sn, Mo, or S) contained in the projection material were all distributed near the surface of the substrate.

[0050] (Hardness) Cross-sectional samples were prepared for each test specimen. For each cross-sectional sample, hardness was measured at multiple locations at different depths from the surface. The measurements were performed according to the method compliant with JIS Z2244:2009. The results are shown in Figure 6. "Hardening depth" is the distance from the surface in the depth direction until a hardness equivalent to that of the untreated substrate is obtained. "Average hardness" is the average of the hardness measured at multiple locations from the surface to the hardening depth.

[0051] As shown in Figure 6, regardless of the substrate material or the projection material of the protective lubrication layer, the surface hardness and average hardness of the treated surface (protective lubrication layer) of the test specimen (substrate) improved compared to the untreated surface. Pretreatment by shot peening increased the average hardness of the substrate surface by 1.1 to 1.6 times compared to the untreated substrate surface. The hardening depth for each test specimen was 0.04 mm to 0.05 mm.

[0052] (Fretting wear test) A fretting abrasion test was conducted on each test specimen. For comparison, the same fretting abrasion test was also performed on an untreated substrate. The test conditions were as follows:

[0053] Countering material: Ni-based heat-resistant alloy Temperature: 300~600℃ Surface pressure: 80~700MPa Frequency: 50~500Hz Amplitude: 0.03~0.5mm

[0054] Figure 7 shows the results of a fretting abrasion test (at 300°C) on a test specimen using a Ni-based heat-resistant alloy as the base material. Figure 8 shows the results of a fretting abrasion test (at 300°C) on a test specimen using a Co-based heat-resistant alloy as the base material. In Figures 7 and 8, the vertical axis represents the percentage change in abrasion amount compared to the untreated specimen.

[0055] According to Figure 7 above, the lower the melting point of the metal oxide interposed on the sliding surface, the lower the amount of wear.

[0056] Compared to untreated substrates without pretreatment or protective lubrication layer formation, the amount of wear was significantly reduced in the pretreated and protective lubrication layer-formed specimens. In specimens using a Ni-based heat-resistant alloy substrate and MoS2 as the abrasive material, wear was reduced by 80% compared to the untreated substrate (see Figure 7). In specimens using a Co-based heat-resistant alloy substrate and MoS2 as the abrasive material, wear was reduced by 88% compared to the untreated substrate (see Figure 8).

[0057] These results suggest that the sliding member according to the above embodiment can achieve a wear reduction effect regardless of the material of the base material (material to be treated). The sliding member according to the above embodiment can be applied to gas turbine combined cycle power plants (GTCC), aircraft engines, turbochargers, etc., which use different materials.

[0058] (Protective lubricating oxide layer) Cross-sectional samples were prepared from the test specimens after the fretting abrasion test. Each cross-sectional sample was subjected to a scanning electron microscope to observe the cross-section and perform elemental analysis.

[0059] Figure 9 shows cross-sectional images taken with a scanning electron microscope. Figure 9(a) is a cross-sectional image of an untreated substrate (Ni-based heat-resistant alloy or Co-based heat-resistant alloy) after sliding. Figure 9(b) is a cross-sectional image of a test specimen after sliding in which a protective lubrication layer was formed by pre-treating the Ni-based heat-resistant alloy or Co-based heat-resistant alloy and then projecting MoS2.

[0060] Regardless of the substrate material, pretreatment, and the presence or absence of a protective lubricating layer, the presence of a separate layer (surface layer) distinct from the substrate was confirmed on the sliding surface after the fretting wear test.

[0061] In Figures 7 and 8, numerous cracks were observed on the sliding surface of the untreated substrate (Ni-based heat-resistant alloy or Co-based heat-resistant alloy) (a), which showed high wear, regardless of the type of substrate. From this, it can be said that the surface layer of (a) is brittle.

[0062] On the other hand, in the sliding surfaces of the test specimens that showed low wear in Figures 7 and 8, where MoS2 was projected after pretreatment, a dense surface layer free of cracks was observed regardless of the type of substrate.

[0063] Figure 10 shows the elemental analysis results of the surface layer of the test specimens after sliding. In Figure 10, (a) is the composition of the surface layer of the sliding surface of the substrate (Ni-based heat-resistant alloy: Inconel-X750), (b) is the composition of the surface layer of the test specimen that was pre-treated and then projected with Sn, and (c) is the composition of the surface layer of the test specimen that was pre-treated and then projected with MoS2.

[0064] In all of the sliding surfaces shown in Figures 10(a) to (c), the surface layer contained a large amount of Ni, a metal element derived from the substrate, and oxygen. From this, it can be said that the surface layer is a Ni-dominant oxide layer. The oxide layer (protective lubricating oxide layer) of the test specimens in (b) and (c) contained metal elements (Sn, Mo, or S) derived from the abrasive material. On the other hand, Sn, Mo, or S were not detected in the oxide layer of the sliding surface of the untreated substrate in (a).

[0065] From the results shown in Figures 9-10 above, it was confirmed that a brittle Ni oxide layer was formed on the sliding surface of the untreated substrate due to friction, while on the sliding surface (after sliding) of the pretreated substrate and the substrate onto which Sn or MoS2 was projected, a dense Ni oxide layer containing oxides derived from the protective lubricating layer was formed due to friction.

[0066] Metal elements derived from the abrasive material can oxidize to metal oxides with melting points of 300-1200°C. It is believed that the formation of such low-melting-point metal oxides on the sliding surface acts as a binder, bonding the metal oxides derived from the base material (substrate), thereby promoting the formation of a dense protective lubricating oxide layer even at low temperatures of around 300°C.

[0067] Figures 7 and 8 above show that the amount of wear on the pre-treated and protective lubrication layer-formed test specimens was significantly reduced compared to the untreated substrate. This suggests that the protective lubrication oxide layer, which contains oxides derived from the protective lubrication layer, exhibits a wear reduction effect at temperatures below 700°C.

[0068] <Note> The manufacturing method and the sliding member described in the embodiments above can be understood, for example, as follows.

[0069] A method for manufacturing a sliding member according to a first aspect of this disclosure is a method for manufacturing a sliding member to be operated in a high-temperature dry environment of 300°C or higher in the presence of oxygen, wherein a projectile is projected onto a substrate surface by shot peening to form a protective lubricating layer on the substrate surface containing metal components derived from the projectile and substrate components, and the material of the projectile is selected from metal elements or metal compounds that can become metal oxides with a melting point of 300 to 1200°C by oxidation.

[0070] When sliding components are operated in a high-temperature, dry environment above 300°C where oxygen is present, the metal components contained in the sliding components are oxidized.

[0071] By using a metal element or metal compound that can become a metal oxide with a melting point of 300-1200°C through oxidation as the material for the projection agent, a low-melting-point metal oxide with a melting point of 300-1200°C is generated on the surface of the sliding member after operation. As a result, the protective lubrication layer becomes a dense protective lubrication oxide layer containing oxides originating from the protective lubrication layer.

[0072] Low-melting-point metal oxides act as binders, binding the metal oxides oxidized from the base material. By including metal components that can serve as sources of low-melting-point metal oxides in the protective lubricant layer, the formation of a dense protective lubricant oxide layer can be promoted even at low temperatures of 300°C. Such a protective lubricant oxide layer can exhibit wear resistance in the operating temperature range of 700°C or below.

[0073] In the method for manufacturing a sliding member according to a second aspect of the present disclosure, in the first aspect, the material of the projection material is selected from the group consisting of Sn, Bi, Mo, Mn, and MoS2.

[0074] The oxides of Sn, Bi, Mo, Mn, and MoS2 are SnO2 (melting point 1127°C), Bi2O3 (melting point 820°C), MoO3 (melting point 795°C), MnO2 (melting point 535°C), and Mn2O3 (melting point 1080°C), respectively.

[0075] In a method for manufacturing a sliding member according to a third aspect of the present disclosure, in the first or second aspect, the material of the projection material is selected such that the melting point of the metal oxide does not fall below the upper limit of the operating temperature of the sliding member.

[0076] Preferably, the melting point of the metal oxides (metal oxides) derived from the abrasive material contained in the protective lubricating oxide layer does not fall below the upper limit of the operating temperature of the sliding member. Preferably, the melting point of the metal oxides is close to the upper limit of the operating temperature of the sliding member.

[0077] In a method for manufacturing a sliding member according to a fourth aspect of the present disclosure, in any of the first to third aspects, hard particles harder than the substrate are used, and before forming the protective lubricating layer, the hard particles are projected onto the substrate surface by shot peening to increase the hardness of the substrate surface.

[0078] By increasing the hardness of the substrate surface before forming a protective lubricating layer, wear can be reduced.

[0079] A sliding member according to a fifth aspect of the present disclosure is a sliding member for operation in a high-temperature dry environment of 300°C or higher in the presence of oxygen, comprising a base material and a protective lubricating layer covering the surface of the base material, wherein the protective lubricating layer contains elements derived from metal elements or metal compounds that can become metal oxides with a melting point of 300 to 1200°C by oxidation, and elements derived from the base material.

[0080] In the sliding member according to the sixth aspect of this disclosure, the metal element or metal compound is one of Sn, Bi, Mo, Mn, and MoS2, as described in the fifth aspect.

[0081] In the sliding member according to the seventh aspect of this disclosure, in the fifth or sixth aspect, the average hardness of the substrate surface is 1.1 or higher than the average hardness of the substrate material.

[0082] A sliding member according to an eighth aspect of the present disclosure is a sliding member for operation in a high-temperature dry environment of 300°C or higher in the presence of oxygen, comprising a base material and a protective lubricating oxide layer covering the surface of the base material, wherein the protective lubricating oxide layer contains metal oxides having a melting point of 300 to 1200°C and oxides of elements derived from the base material.

[0083] In the sliding member according to the ninth aspect of this disclosure, in the eighth aspect, the metal oxide is one of SnO2, Bi2O3, MoO3, MnO2, and Mn2O3. [Explanation of Symbols]

[0084] 1. Sliding member 2 Base material 3 Protective lubricant layer 4. Protective lubricating oxide layer 10 Gas turbine blades 11 Wings 12 platforms 13 Wing root 14 Proximal end 15 Tip 16 Leading edge 17 Trailing edge 18 Negative pressure side (back) 19 Groove 20 Seal pin grooves 21 Seal pins 22 End face on the negative pressure side (back side)

Claims

1. A method for manufacturing a sliding member to operate in a high-temperature dry environment of 300°C or higher where oxygen is present, By shot peening, a projectile is projected onto the substrate surface to form a protective lubricating layer on the substrate surface containing the components of the projectile and the substrate components. A method for manufacturing a sliding member, wherein the material of the projection material is selected from a metal element or metal compound that can become a metal oxide with a melting point of 300 to 1200°C upon oxidation.

2. The material of the projection material is Sn, Bi, Mo, Mn, and MoS ２ A method for manufacturing a sliding member according to claim 1, selected from the group consisting of the following.

3. The method for manufacturing a sliding member according to claim 1, wherein the material of the projection material is selected such that the melting point of the metal oxide does not fall below the upper limit of the operating temperature of the sliding member.

4. Using hard particles that are harder than the aforementioned substrate, The method for manufacturing a sliding member according to claim 1, wherein, before forming the protective lubricating layer, the hard particles are projected onto the substrate surface by shot peening to increase the hardness of the substrate surface.

5. A sliding member for operation in a high-temperature dry environment of 300°C or higher where oxygen is present, The device comprises a base material and a protective lubricating layer covering the surface of the base material, The protective lubricating layer is a sliding member comprising elements derived from metal elements or metal compounds that can become metal oxides with a melting point of 300 to 1200°C upon oxidation, and elements derived from the base material.

6. Metallic elements or metal compounds include Sn, Bi, Mo, Mn, and MoS ２ The sliding member according to claim 5, which is any of the above.

7. The sliding member according to claim 5, wherein the average hardness of the substrate surface is 1.1 or higher than the average hardness of the material of the substrate.

8. A sliding member for operation in a high-temperature dry environment of 300°C or higher where oxygen is present, The device comprises a base material and a protective lubricating oxide layer covering the surface of the base material, The protective lubricating oxide layer comprises a metal oxide with a melting point of 300 to 1200°C and an oxide of an element derived from the substrate, in the sliding member.

9. The metal oxide is SnO ２ , Bi ２ O ３ , MoO ３ , MnO ２ and Mn ２ O ３ The sliding member according to claim 8, which is any one of them.

Images