Manufacturing method of sliding component, sliding component and piston ring

Abstract

A manufacturing method for a sliding member, the sliding member comprising a substrate and a coating disposed to cover at least a portion of the surface of the substrate, wherein the manufacturing method comprises: (A) a step of obtaining an intermetallic compound containing Cr and at least Si; and (B) a step of forming the coating using the intermetallic compound by arc ion plating, wherein in step (B), a bias voltage in the range of -2V to -25V is set under a nitrogen atmosphere. The sliding member comprises a substrate and a coating disposed to cover at least a portion of the surface of the substrate, the coating containing Cr and N and at least Si, the coating having a matrix portion and a dispersed particle portion dispersed within the matrix portion, and the coating having a hardness of 1900 HV0.1 or less.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a sliding member, a sliding member, and a piston ring. Background Technology

[0002] Piston rings and other sliding components are used in engines, such as those in automobiles. Piston rings are fitted into grooves on the outer circumferential surface of the piston. Piston rings are required to contribute to engine performance and reduce fuel consumption by possessing properties such as wear resistance and resistance to sintering. Various efforts have been made in the past to improve the wear resistance of piston rings.

[0003] For example, the invention described in Patent Document 1 is made to provide a sliding member with excellent wear resistance even under harsh conditions in engines employing direct fuel injection or exhaust gas recirculation (EGR). In this sliding member, a substrate is covered with a coating composed of a mixture of crystalline and amorphous phases, wherein the crystalline phase is composed of metal nitrides, metal carbides, or metal carbonitrides.

[0004] The invention described in Patent Document 2 is for providing a piston ring for an internal combustion engine that combines wear resistance, crack resistance, and peel resistance. In this piston ring, a hard coating is formed at least on the outer peripheral sliding surface. This hard coating is composed of a crystalline phase with Cr, N, and Si as constituent elements, having the same crystal structure as CrN, and in which Si is dissolved in a lattice at a ratio of 1% or more and 9.5% or less in terms of atomic proportions.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2002-266697

[0008] Patent Document 2: Japanese Patent Application Publication No. 2008-14228 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] Sliding components not only require excellent wear resistance themselves but also low aggression towards mating materials. Therefore, a high degree of balance between wear-free sliding components and mating materials is necessary. Furthermore, in recent years, to address the increasing power output of engines and exhaust emission restrictions, advancements have been made in areas such as higher combustion temperatures, the use of low-viscosity lubricants, and reduced oil volume. Additionally, FFV (Flexible Fuel Vehicle) vehicles, which blend gasoline and biofuels in a wide range of ratios, are also gaining popularity. Consequently, the operating environment for sliding components is becoming increasingly demanding, and they are increasingly becoming boundary lubrication environments. This leads to increased wear on the coating of sliding components and peeling of the coating due to increased sliding resistance.

[0011] Therefore, the present invention provides a method for manufacturing a sliding member, a sliding member, and a piston ring that exhibit excellent peel resistance even under harsh environments, a good balance between wear resistance and the aggressiveness of the mating materials, and can be achieved at a sufficiently high level.

[0012] means for solving problems

[0013] This invention includes, for example, the following.

[0014] [1] A manufacturing method for a sliding member having a substrate and a coating disposed such that it covers at least a portion of the surface of the substrate, wherein the manufacturing method comprises: (A) a step of obtaining an intermetallic compound containing Cr and at least Si; and (B) a step of forming the coating using the intermetallic compound by arc ion plating, wherein in step (B), a bias voltage in the range of -2V to -25V is set under a nitrogen atmosphere.

[0015] [2] A sliding member, wherein the sliding member comprises a substrate and a coating disposed such that it covers at least a portion of the surface of the substrate, the coating containing Cr and N and a metallic element including at least Si, the coating having a matrix portion and a dispersed particle portion dispersed in the matrix portion, the hardness of the coating being 1900HV0.1 or less.

[0016] [3] According to the sliding member of [2], wherein the metal element comprises at least one selected from the group consisting of Ti, Al, Mo, V, W, Nb, Mn, Zn, Cu and Zr.

[0017] [4] According to the sliding member described in [2] or [3], the content of the metal element in the matrix portion is 1 atomic% to 25 atomic%.

[0018] [5] The sliding member according to any one of [2] to [4], wherein the content of the metal element in the dispersed particle portion is greater than the content of the metal element in the matrix portion.

[0019] [6] The sliding member according to any one of [2] to [5], wherein the hardness of the coating is 800HV0.1 to 1500HV0.1.

[0020] [7] A piston ring, wherein the piston ring comprises any one of [2] to [6].

[0021] Invention Effects

[0022] According to the present invention, a method for manufacturing a sliding member, a sliding member, and a piston ring are provided, which exhibit excellent peel resistance even under harsh environments and have a good balance between wear resistance and the aggressiveness of the mating material (mutual aggression), and can be achieved at a sufficiently high level. Attached Figure Description

[0023] Figure 1 This is a schematic cross-sectional view of a sliding member according to one embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the surface of the coating in a sliding member according to one embodiment of the present invention.

[0025] Figure 3 The results are from the EPMA analysis of the piston ring surface in Example 1.

[0026] Figure 4 This is a binarized image of the piston ring surface of Example 1.

[0027] Figure 5 This is a schematic diagram illustrating the structure of a sliding fatigue testing machine. Detailed Implementation

[0028] The embodiments of the present invention will now be described in detail. It should be noted that the present invention is not limited to the following embodiments.

[0029] (Sliding component)

[0030] Figure 1 This is a schematic cross-sectional view of a sliding member according to one embodiment of the present invention. Figure 1The sliding member 10 shown includes a substrate 1 and a coating 5 disposed to cover at least a portion of the surface of the substrate 1. The coating 5 may also be disposed on the outer peripheral surface of the substrate 1 (the surface corresponding to the sliding surface 10F). The sliding member 10 is, for example, a pressure ring (piston ring) for an internal combustion engine (e.g., an automobile engine). The pressure ring is, for example, mounted in an annular groove formed on the side of the piston. The pressure ring is a ring particularly exposed to the high thermal load environment of the engine.

[0031] When the sliding component is a piston ring, the piston ring is annular, for example, with an outer diameter of 40mm to 300mm. The term "annular" here can refer to a closed circle or a roughly circular shape with an opening. Furthermore, the piston ring can be perfectly circular or elliptical when viewed from above. The cross-section of the piston ring is roughly rectangular, and the sliding surface may have a rounded, outward-bulging shape.

[0032] The substrate contains a heat-resistant alloy. Specific examples of alloys include spring steel and martensitic stainless steel. A nitrided layer may be formed on the surface of the substrate.

[0033] The coating comprises Cr-Me-N type materials (Me represents a metallic element). From the viewpoint of achieving a better balance of wear resistance, peel resistance, and material aggression resistance, the metallic element Me must contain at least Si. In addition to Si, the metallic element Me may also contain at least one element selected from the group consisting of Ti, Al, Mo, V, W, Nb, Mn, Zn, Cu, and Zr.

[0034] The thickness of the coating can be, for example, 5 μm to 70 μm or 10 μm to 50 μm. A coating thickness of 5 μm or more tends to improve the durability of the sliding component, while a coating thickness of 70 μm or less ensures high productivity of the coating.

[0035] like Figure 2 As shown, the coating 5 has a matrix portion 5A and a dispersed particle portion 5B scattered within the matrix portion 5A. The fact that the coating has a matrix portion and a dispersed particle portion can be confirmed by observing the coating using a scanning electron microscope (SEM or FE-SEM) and by obtaining the resulting reflectance electron image.

[0036] Both the matrix and the dispersed particle section contain Cr-Me-N type materials, but the content of each element differs. From the perspective of achieving a better balance in wear resistance, peel resistance, and the aggression resistance of the compound material, the content of metal elements in the dispersed particle section can be greater than that in the matrix section. It should be noted that the dispersed particle section containing metal elements such as Si is also referred to as the alloy composition dispersed particle section.

[0037] The equivalent circle diameter of the dispersed particle section is, for example, 0.1 μm to 10 μm. The equivalent circle diameter of the dispersed particle section can be determined by observing the surface of the coating using SEM or similar methods and based on the obtained reflectance electron image.

[0038] The elemental composition of the matrix and dispersed particle portions of the sliding member was determined using the method described below. First, the coating surface formed on the outer peripheral surface of the sliding member was ground using a grinding mill (e.g., IS-POLISHER manufactured by Ikegami Seiki Co., Ltd.). Specifically, the particle size was gradually increased from #600, ultimately using a diamond film with a particle size of 0.5 μm to obtain a sample. Next, an elemental concentration map was obtained from the obtained sample using an EPMA (e.g., JXA-8100 manufactured by Nippon Electron Co., Ltd.). The measurement conditions were: accelerating voltage 15 kV, irradiation current 5.0 × 10⁻⁶ kV. -8 A. With a beam diameter of 0 μm (minimum setting), scan interval (vertical: 0.30 μm, horizontal: 0.30 μm), scan time of 30 ms / point, and number of scan points (vertical: 200 points × horizontal: 200 points), a concentration map (60 μm × 60 μm) of each analyte is obtained. It should be noted that even when the beam diameter is set to the minimum setting for EPMA, the actual beam diameter will not be 0 μm, but rather a beam diameter in the nm range. Regarding the elemental amounts in the matrix and dispersed particle regions, the largest dispersed particle region (at least a dispersed particle region with an equivalent circle diameter of 2 μm or more) is selected from the concentration map. A line scan is performed through this dispersed particle region, and the concentration of each element at the scan position is determined using a distribution map. When scanning small dispersed particles, the matrix region surrounding the dispersed particles is also analyzed. Therefore, the elemental concentration in the dispersed particle region is not the true value, but rather shifted towards the elemental concentration in the matrix region, which is undesirable. In the concentration distribution map obtained by such operation, the baseline of the distribution map is taken as the average concentration of the matrix, the concentration of the part corresponding to the dispersed particles is taken as the maximum concentration of the dispersed particles, and the concentration of the matrix can be compared with the concentration of the dispersed particles.

[0039] In one embodiment of the present invention, the coating of the sliding member contains Cr and N, as well as a metallic element including at least Si, and has a matrix portion and a dispersed particle portion dispersed within the matrix portion. The hardness of the coating is 1900 HV0.1 or less, thereby achieving an excellent balance of wear resistance, peel resistance, and resistance to aggression from the cooperating material. The inventors speculate the following reasons for this.

[0040] <1> The dispersed particles in the matrix of the coating of the sliding component contain not only Cr, but also metallic elements such as Si. As a result, the dispersed particle part (alloy component dispersed particle part) is firmly bonded to the matrix part, thus increasing the overall toughness of the coating and making it difficult to become the starting point of peeling caused by sliding resistance, thereby improving peel resistance.

[0041] <2> By including not only Cr but also other metallic elements in the dispersed particles, a lubricating coating called a friction film is formed through reaction with lubricating oil during the sliding of the coating and the mating materials. The lubricating coating functions as a protective film, thereby improving wear resistance and reducing the aggression of the mating materials.

[0042] <3> When the hardness of the coating is too high, its flexibility decreases, stress tends to concentrate, and cracks easily form. The coating is prone to peeling and wear on the mating materials. Lowering the hardness of the coating to a certain extent improves peel resistance and reduces the aggression of the mating materials. Furthermore, generally speaking, low coating hardness tends to result in insufficient wear resistance; however, by including metallic elements such as Si in the dispersed particle section, the wear resistance of the dispersed particle section itself is improved.

[0043] Based on the above mechanism, compared with the dispersed Cr particles that do not contain metallic elements such as Si, even if the overall hardness of the coating is reduced, the wear resistance of the coating can be ensured, and the overall toughness of the coating is increased, making it difficult for the coating to peel off, thus improving peel resistance. However, the mechanism of the present invention is not limited to the above.

[0044] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggression resistance of the compound material, the Cr content in the matrix can be 30 atomic% or more, 35 atomic% or more, or 40 atomic% or more. From the same perspective, it can be 60 atomic% or less, 55 atomic% or less, or 50 atomic% or less. Therefore, the Cr content in the matrix can be between 30 atomic% and 60 atomic%.

[0045] From the perspective of achieving a superior balance between wear resistance, peel resistance, and the aggression resistance of the compound material, the total content of metallic elements in the matrix can be 1 atom% or more, 3 atom% or more, or 5 atom% or more. Similarly, from the same perspective, it can be 25 atom% or less, 22 atom% or less, 20 atom% or less, 15 atom% or less, 12 atom% or less, 10 atom% or less, 8 atom% or less, 7 atom% or less, 6 atom% or less, 5 atom% or less, 4 atom% or less, 3.5 atom% or less, or 3 atom% or less. From these perspectives, the total content of metallic elements in the matrix can be 1 atom% to 25 atom%, 1 atom% to 20 atom%, 1 atom% to 12 atom%, 1 atom% to 8 atom%, 1 atom% to 5 atom%, or 1 atom% to 3 atom%.

[0046] From the perspective of achieving a better balance of wear resistance, peel resistance, and aggression resistance to the compound material, the Si content in the matrix can be 1 atom% or more, 2 atom% or more, or 3 atom% or more. Similarly, from the same perspective, it can be 8 atom% or less, 7 atom% or less, 6 atom% or less, 5 atom% or less, 4 atom% or less, 3.5 atom% or less, or 3 atom% or less. From these perspectives, the Si content in the matrix can be 1 atom% to 8 atom%, 1 atom% to 5 atom%, or 1 atom% to 3.5 atom%.

[0047] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggression resistance of the compound material, the Ti content in the matrix can be 0 atomic% or more, 4 atomic% or more, or 7 atomic% or more. Similarly, from the same perspective, it can be 25 atomic% or less, 20 atomic% or less, or 17 atomic% or less. Therefore, the Ti content in the matrix can range from 0 atomic% to 25 atomic%.

[0048] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggressiveness of the compounding materials, the total Si and Ti content in the matrix can be 1 atom% or more, 6 atom% or more, or 10 atom% or more. Similarly, from the same perspective, it can be 30 atom% or less, 24 atom% or less, or 20 atom% or less. Therefore, from these perspectives, the total Si and Ti content in the matrix can range from 1 atom% to 30 atom%.

[0049] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggression resistance of the compound material, the nitrogen content in the matrix can be 35 atomic% or more, 40 atomic% or more, or 45 atomic% or more. From the same perspective, it can be 65 atomic% or less, 60 atomic% or less, or 55 atomic% or less. Therefore, the nitrogen content in the matrix can be between 35 atomic% and 65 atomic%.

[0050] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggression resistance of the compound material, the Cr content in the dispersed particle portion can be 40 atomic% or more, 45 atomic% or more, or 50 atomic% or more. From the same perspective, it can be 80 atomic% or less, 75 atomic% or less, or 70 atomic% or less. Therefore, the Cr content in the dispersed particle portion can be between 40 atomic% and 80 atomic%.

[0051] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggression resistance of the compound material, the total content of metal elements in the dispersed particle section can be 1 atomic% or more, 3 atomic% or more, or 5 atomic% or more. Similarly, from the same perspective, it can be 30 atomic% or less, 26 atomic% or less, 24 atomic% or less, 22 atomic% or less, 20 atomic% or less, 15 atomic% or less, or 10 atomic% or less. The total content of metal elements in the dispersed particle section can be 1 atomic% to 30 atomic%, 1 atomic% to 24 atomic%, 1 atomic% to 20 atomic%, 1 atomic% to 15 atomic%, or 1 atomic% to 10 atomic.

[0052] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggression resistance of the compound material, the Si content in the dispersed particle section can be 2 atomic% or more, 3 atomic% or more, 4 atomic% or more, or 5 atomic% or more. From the same perspective, it can be 15 atomic% or less, 13 atomic% or less, 10 atomic% or less, 8 atomic% or less, or 6 atomic% or less. Therefore, from these perspectives, the Si content in the dispersed particle section can be 2 atomic% to 15 atomic% or 3 atomic% to 10 atomic%.

[0053] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggression resistance of the compound material, the Ti content in the dispersed particle portion can be 0 atomic% or more, 6 atomic% or more, or 9 atomic% or more. Similarly, from the same perspective, it can be 30 atomic% or less, 22 atomic% or less, or 19 atomic% or less. Therefore, the Ti content in the dispersed particle portion can range from 0 atomic% to 30 atomic%.

[0054] From the perspective of achieving a better balance of wear resistance, peel resistance, and the aggression resistance of the compounding materials, the total Si and Ti content in the dispersed particle section can be 3 atomic% or more, 10 atomic% or more, or 14 atomic% or more. From the same perspective, it can be 40 atomic% or less, 30 atomic% or less, or 25 atomic% or less. Therefore, from these perspectives, the total Si and Ti content in the dispersed particle section can be between 3 atomic% and 40 atomic%.

[0055] From the viewpoint of achieving a better balance between wear resistance, peel resistance, and the aggression resistance of the compound material, the N content in the dispersed particle portion can be 10 atomic% or more, 15 atomic% or more, or 20 atomic% or more. From the same viewpoint, it can be 50 atomic% or less, 45 atomic% or less, or 40 atomic% or less. Therefore, the N content in the dispersed particle portion can be between 10 atomic% and 50 atomic%.

[0056] From the perspective of achieving a better balance of wear resistance, peel resistance, and the aggressiveness of the compound material, the difference between the total metal content of the dispersed particle part and the total metal content of the matrix part (dispersed particle part - matrix part) can be 0.5 atomic% or more, 1 atomic% or more, or 1.5 atomic% or more. From the same perspective, it can be 3 atomic% or less, 2.5 atomic% or less, or 2 atomic% or less.

[0057] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggressiveness of the compound material, the difference in Si content between the dispersed particle part and the matrix part (dispersed particle part - matrix part) can be more than 1 atomic% or more, more than 2 atomic% or more, or more than 2.5 atomic%; from the same perspective, it can be less than 5 atomic% or less, less than 4 atomic% or less, or less than 3 atomic%.

[0058] From the viewpoint of achieving a superior balance between wear resistance, peel resistance, and resistance to aggression from mating materials, the area proportion of dispersed particles with an equivalent circle diameter of 0.1 μm or more on the surface of the coating can be 0.5% to 5%. With an area proportion of dispersed particles with an equivalent circle diameter of 0.1 μm or more of 0.5%, a suitable gap can be created between the sliding member and the mating material, thus tending towards a superior balance between wear resistance, peel resistance, and resistance to aggression from mating materials. With an area proportion of dispersed particles with an equivalent circle diameter of 0.1 μm or more of 5% or less, the shedding of dispersed particles can be suppressed, tending towards a superior balance between wear resistance, peel resistance, and resistance to aggression from mating materials. From the viewpoint of achieving a superior balance between wear resistance, peel resistance, and resistance to aggression from mating materials, the area proportion of dispersed particles with an equivalent circle diameter of 0.1 μm or more on the surface of the coating can be greater than 1.0%, or less than 4.5% or less, or less than 4%.

[0059] The area ratio of dispersed particles with an equivalent circle diameter of 0.1 μm or more on the surface of the coating can be determined by the following method: The surface of the coating on the sliding member is ground using a grinding machine (e.g., IS-POLISHER manufactured by Ikegami Seiki Co., Ltd.). Specifically, the particle size is gradually increased from #600, eventually using a diamond film with a particle size of 0.5 μm to obtain a sample. The obtained sample is then observed using an FE-SEM (e.g., JSM-7100F manufactured by Nippon Electron Ltd.), and a reflected electron image is obtained at 2000x magnification. A 45 μm × 62.5 μm region is extracted from the obtained reflected electron image, and binarized using image analysis software (e.g., A-Image-kun manufactured by Asahi Kasei Engineering Co., Ltd.). The total area of ​​dispersed particles with an equivalent circle diameter of 0.1 μm or more is determined from the binarized image. The area ratio can be calculated by dividing the total area of ​​the dispersed particles with an equivalent circle diameter of 0.1 μm or more by the measured area (45 μm × 62.5 μm).

[0060] The hardness of the coating is below 1900 HV0.1. A hardness of 1900 HV0.1 or less provides an excellent balance between peel resistance and the aggression of the mating materials. From the viewpoint of achieving moderate elastic deformation, reducing Hertzian stress caused by slippage, and easily obtaining excellent peel resistance, the hardness of the coating can be 800 HV0.1–1800 HV0.1, 800 HV0.1–1500 HV0.1, 900 HV0.1–1500 HV0.1, or 1000 HV0.1–1300 HV0.1. The hardness of the coating can be determined using a Vickers hardness tester (e.g., device name: HM-220, manufactured by Mitutoyo) according to the method specified in ISO 6507.

[0061] (Manufacturing method of sliding components)

[0062] Next, the manufacturing method of the sliding member will be described. The manufacturing method of this embodiment includes the following steps.

[0063] (a) A process for obtaining an intermetallic compound containing Cr and at least Si.

[0064] (b) A process of forming a coating using an intermetallic compound by arc ion plating.

[0065] (a) The process involves mixing powders containing Cr and metallic elements, cold forming them, and sintering them by hot isostatic pressing (HIP) or hot pressing to obtain an intermetallic compound of a specified shape.

[0066] (a) In the process, firstly, Cr is used as the main constituent element, and a metal element containing at least Si is used as a secondary constituent element. Cr-containing metal powder and Si-containing metal powder are mixed in a predetermined amount. In addition to Cr-containing and Si-containing metal powders, metal powders containing at least one element selected from the group consisting of Ti, Al, Mo, V, W, Nb, Mn, Zn, Cu, and Zr can also be used. The metal powder can contain multiple metal elements. There are no particular limitations on the method of manufacturing the metal powder. The metal powder can be a powder consisting substantially of only a single element, or it can be a powder obtained by melting and pulverizing multiple components. Alternatively, it can be a powder obtained by alloying in a solid-state state, such as through mechanical alloying.

[0067] Next, the mixed metal powder is cold-formed into a specified shape using a stamping press or similar method, and then sintered by hot isostatic pressing (HIP) or hot pressing to obtain a target material containing intermetallic compounds of a specified shape.

[0068] The sintering temperature during hot isostatic pressing (HIP) or hot pressing can be, for example, 900℃~1300℃ or 900℃~1100℃.

[0069] The pressure during sintering via hot isostatic pressing (HIP) or hot pressing can be, for example, 100 MPa to 140 MPa.

[0070] By adjusting the type, mixing ratio, and sintering conditions of the materials used to obtain the intermetallic compound, it is possible to regulate the amount of dispersed particles and the size of the dispersed particle portion during film formation while simultaneously dispersing the dispersed particles in the coating. For example, by reducing the sintering pressure during the formation of the intermetallic compound, the formation of intermetallic compounds of metal elements such as Cr and Si in the dispersed particle portion of the coating can be suppressed.

[0071] The manufacturing method of the sliding component may include a step prior to step (b) to clean the surface of the substrate. For example, it may include a step of cleaning by degreasing or shot peening. Alternatively, the manufacturing method of the sliding component may include a step of performing bombardment cleaning within a cavity.

[0072] (b) The coating formation in the process can be carried out by arc ion plating. Specifically, the chamber is set to a nitrogen atmosphere, and the bias voltage is set to a range of -2V to -25V. By using an intermetallic compound to form the coating by arc ion plating with a bias voltage of -2V to -25V, it is possible to prevent the coating from becoming too dense and to mitigate residual stress within the coating. As a result, it is possible to manufacture sliding components that exhibit excellent peel resistance even under harsh environments, and that achieve a good balance between wear resistance and the aggressiveness of the mating materials, at a sufficiently high level. From the viewpoint of achieving a better balance of wear resistance, peel resistance, and the aggressiveness of the mating materials in the sliding component, the bias voltage can be -3V to -15V or -4V to -10V.

[0073] From the perspective of achieving a better balance between wear resistance, peel resistance, and the aggressiveness of the mating materials in the sliding components, the nitrogen pressure in the chamber can be 1 Pa to 10 Pa, 2 Pa to 8 Pa, or 4 Pa ​​to 6.5 Pa. The film-forming temperature can be, for example, 300℃ to 500℃. The arc current can be 100A to 200A.

[0074] By means of electric arc discharge, constituent elements ionized from the target material containing intermetallic compounds are vapor-deposited onto the substrate applied to the cathode, thereby forming a matrix portion containing a coating of constituent elements. At the same time, molten droplets generated at the arc point on the surface of the intermetallic compound are also released and dispersed as dispersed particles within the matrix portion.

[0075] Example

[0076] The present invention will now be described in more detail based on inventive examples and comparative examples. The present invention is not limited to the inventive examples described below.

[0077] (Examples 1 to 14 of the Invention and Comparative Examples 1 to 9 of the Comparative Examples)

[0078] <Formation of the coating>

[0079] JIS SWOSC-V (silicon-chromium steel oil tempering wire) was used as the substrate for the sliding member (piston ring) and processed into a ring shape. Next, as preparation for film formation, the substrate was degreased and cleaned, and then the ring substrate was placed in an ion plating apparatus. Then, in the chamber, the chamber atmosphere was set to nitrogen, and at the nitrogen pressure, bias voltage, and film formation temperature of 400°C shown in Table 1, the target material (containing metal compounds or intermetallic compounds) with the composition shown in Table 1 was ionized, thereby forming a coating with a thickness of approximately 20 μm on the substrate surface. At this time, the arc current of Invention Examples 1-14, Comparative Examples 1, 2, 4-8, and 9 was 150 A, the arc current of Comparative Example 3 was 100 A, and the arc current of Comparative Example 7 was 350 A. It should be noted that the metal powder containing Cr and the metal powder containing any metal element were mixed in a specified amount so that the intermetallic compound became the target composition shown in Table 1. The mixture was cold-formed using a stamping press and then sintered in the range of 900℃ to 1300℃ and 100MPa to 140MPa by hot isostatic pressing (HIP).

[0080] The elemental composition of the matrix and dispersed particle portions of the fabricated piston rings was determined using the method described below. First, the coated surface formed on the outer circumference of the piston rings was ground using a grinding mill (IS-POLISHER, manufactured by Ikegami Seiki Co., Ltd.). Specifically, the particle size was gradually increased from #600, and a sample was obtained by grinding with a diamond film with a particle size of 0.5 μm. Next, the elemental concentration profile was obtained from the obtained sample using an EPMA (device name: JXA-8100, manufactured by Nippon Electron). The measurement conditions were set as follows: accelerating voltage 15 kV, irradiation current 5.0 × 10⁻⁶. -8 A. Beam diameter 0 μm (minimum setting), scan interval (vertical: 0.30 μm, horizontal: 0.30 μm), scan time 30 ms / point, number of scan points (vertical: 200 points × horizontal: 200 points), thus obtaining a concentration map (60 μm × 60 μm) for each analyzed element. Regarding the elemental amounts in the matrix and dispersed particle portions, the largest dispersed particle portion was selected from the concentration map, and a line scan was performed through this dispersed particle portion. The concentration of each element at the scan position was determined using the distribution map. In the concentration distribution map obtained by this operation, the baseline of the distribution map was taken as the average concentration of the matrix portion, and the concentration corresponding to the dispersed particle portion was taken as the maximum concentration of the dispersed particles. The concentrations of the matrix portion and the dispersed particle portion were compared. The EPMA analysis results of the piston ring surface of Example 1 are shown below. Figure 3 It should be noted that, Figure 3 In the diagram, the darker the black area, the higher the Si concentration.

[0081] Table 1

[0082] <Coating Characteristics>

[0083] Table 1 shows the characteristics of the coating on the piston rings of the embodiments and comparative examples. It should be noted that each characteristic was measured using the following methods.

[0084] (Area ratio of dispersed particles)

[0085] The surface of the coated piston ring was ground using a grinding mill (IS-POLISHER manufactured by Ikegami Seiki Co., Ltd.). Specifically, the grit size was gradually increased from #600, and finally a diamond film with a grit size of 0.5 μm was used to grind the sample. The sample was then observed using an FE-SEM (JSM-7100F manufactured by Nippon Electron Ltd.), and a reflected electron image was obtained at 2000x magnification. A 45 μm × 62.5 μm region was extracted from the obtained reflected electron image and binarized using image analysis software (e.g., A-Image-Kun manufactured by Asahi Kasei Engineering Co., Ltd.). The binarized image of the piston ring surface of Example 1 is shown below. Figure 4 It should be noted that, Figure 4 In the image, the black areas represent the matrix, and the white areas represent the dispersed particles. The total area of ​​dispersed particles with an equivalent circle diameter of 0.1 μm or more was measured from the binarized image. The area ratio of dispersed particles with an equivalent circle diameter of 0.1 μm or more was calculated by dividing the total area by the measured area (45 μm × 62.5 μm). The evaluation criteria for the area ratio of dispersed particles are as follows.

[0086] A: The area ratio is less than 1%.

[0087] B: Area proportion greater than 1% and less than or equal to 4%.

[0088] C: Area proportion greater than 4%.

[0089] (hardness)

[0090] The hardness HV of the coating is obtained by using a Vickers hardness tester (equipment name: HM-220, manufactured by Mitutoyo) and according to the method specified in ISO 6507, with a test load of 0.98N.

[0091] <Sliding Fatigue Test>

[0092] As a wear acceleration test, using Figure 5 The testing machine with the structure shown was used for sliding fatigue testing. Figure 5The testing machine 50 shown includes: a rotating drum 51; a mechanism for bringing the test piece S (piston ring cutter) into contact with the surface of the drum 51; a mechanism for repeatedly applying load to the test piece S; and a mechanism for supplying lubricating oil to the sliding part. This allows the test piece to wear out in a relatively short time. The test conditions are as follows.

[0093] • Test load: 20N~80N, sine curve (50Hz)

[0094] • Matching material (roller): SUJ2 heat-treated material (80mm diameter)

[0095] • Movement speed: Trapezoidal operation in both forward and reverse directions

[0096] • Lubricating oil: Base oil (0.1cc, dripped once every 30 seconds)

[0097] • Drum surface temperature: 80℃

[0098] • Test duration: 2-3 minutes per cycle, 5 cycles in total.

[0099] <Evaluation>

[0100] Table 1 shows the evaluation results of the coatings on the piston rings of the Examples and Comparative Examples. It should be noted that each evaluation result was based on 20 piston rings of each Example and Comparative Example, which underwent 20 sliding fatigue tests. The coatings after the sliding fatigue tests were visually observed, and the peel resistance of the coatings was evaluated. Furthermore, the wear amount of the coating in Comparative Example 1 was used as the wear amount of a conventional CrN coating to evaluate the wear resistance and the aggression of the mating materials. The evaluation criteria are as follows.

[0101] (Peel resistance)

[0102] A: The rate of peeling was less than 40% in 20 samples.

[0103] B: Among the 20 samples, the rate of peeling was greater than 40% and less than 80%.

[0104] C: Among the 20 samples, the rate of peeling was over 80%.

[0105] (Abrasion resistance)

[0106] Wear amount when the wear amount of the previous CrN coating is set to 1.0

[0107] A: The wear amount is below 0.7.

[0108] B: Wear amount is greater than 0.7 and less than 0.9.

[0109] C: Wear amount is 0.9 or higher.

[0110] (In conjunction with the material's offensive capabilities)

[0111] Wear amount when the wear of the compound material (SUJ2 heat-treated material) caused by the previous CrN coating is set to 1.0.

[0112] A: The wear amount is below 1.0.

[0113] B: Wear amount is greater than 1.0 and less than 1.2.

[0114] C: Wear amount is 1.2 or more.

[0115] Industrial practicality

[0116] According to the present invention, a piston ring and a method for manufacturing the same are provided. The piston ring is provided with a coating comprising Cr and N, and at least one metallic element selected from Si, Ti, Al, Mo, V and W. The piston ring achieves a good balance of all properties, including wear resistance, peel resistance and resistance to aggression from the mating materials, and these properties can be achieved at a sufficiently high level.

[0117] Label Explanation

[0118] 1…substrate, 5…coating, 5A…matrix, 5B…dispersed particle part, 10…sliding member, 10F…sliding surface.

Claims

1. A manufacturing method for a sliding member, the sliding member comprising a substrate and a coating disposed to cover at least a portion of the surface of the substrate, wherein, The manufacturing method includes: (A) A process for obtaining an intermetallic compound containing Cr and at least Si; and (B) The process of forming the coating using the intermetallic compound via arc ion plating. In process (B), a bias voltage in the range of -2V to -25V is set under a nitrogen atmosphere.

2. A sliding member, wherein, The sliding member comprises: a substrate and a coating disposed in a manner that covers at least a portion of the surface of the substrate. The coating contains Cr and N, as well as a metallic element containing at least Si. The coating has a matrix portion and a dispersed particle portion dispersed within the matrix portion. The hardness of the coating is below 1900HV0.

1.

3. The sliding member according to claim 2, wherein, The metallic element comprises at least one selected from the group consisting of Ti, Al, Mo, V, W, Nb, Mn, Zn, Cu, and Zr.

4. The sliding member according to claim 2 or 3, wherein, The content of the metal element in the matrix is ​​1 atomic% to 25 atomic%.

5. The sliding member according to claim 2 or 3, wherein, The content of the metal element in the dispersed particle section is greater than the content of the metal element in the matrix section.

6. The sliding member according to claim 2 or 3, wherein, The hardness of the coating is 800HV0.1 to 1500HV0.

1.

7. A piston ring, wherein, The piston ring includes the sliding member as described in claim 2 or 3.

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