Plain bearing and method for producing a plain bearing

Abstract

The present invention provides a sliding bearing with excellent non-sintering properties. The sliding bearing of the present invention comprises a base layer and a coating layer. The coating layer is composed of at least two covering layers and at least one intermetallic compound-containing layer between the adjacent covering layers, the intermetallic compound-containing layer comprising a layered metal portion in an intermetallic compound matrix. The area of the layered metal portion is 60% to 95% of the area of the intermetallic compound-containing layer. The present invention also relates to a method for manufacturing the sliding bearing.

Description

Technical Field

[0001] This invention particularly relates to the coating structure of sliding bearings used in internal combustion engines or piston compressors. Especially relevant is the coating structure of sliding bearings exhibiting excellent non-sintering properties under abnormal loads. This invention also relates to a method for manufacturing this sliding bearing. Background Technology

[0002] Sliding components such as flat bearings in internal combustion engines often incorporate copper or aluminum lining alloys bonded to a steel lining metal. Copper or aluminum alloys provide strong, tough surfaces capable of withstanding the loads borne by the sliding components during operation. Such sliding components require not only good embedding and adaptability but also suitable non-sintering properties. For this purpose, a soft coating layer is typically applied to the lining layer (bearing alloy layer).

[0003] For example, Patent Document 1 (Japanese Patent Application Publication No. 2002-310158) discloses a multilayer sliding material in which a tin-copper tin-based capping layer is provided on a bearing alloy layer, with an intermediate layer in place to prevent copper diffusion. In this document, in order to prevent the reduction of copper in the surface portion of the capping layer composed of tin-based alloy from occurring even when the intermediate layer is not thick, multiple layers with different copper contents are provided, thereby achieving non-sintering maintenance.

[0004] On the other hand, in order to improve wear resistance and non-sintering properties, Patent Document 2 (Japanese Patent Application Publication No. 11-182549) discloses a sliding bearing that improves wear resistance by dispersing hard particles with an average particle size of less than 15 μm at a volume percentage of 0.3 to 25% in the main load-bearing part of the cover, making sintering less likely to occur.

[0005] In the operating environment of sliding bearings, the working conditions of the application or external disturbances may potentially lead to abnormal loads exceeding the design specifications. For example, when a vehicle equipped with a sliding bearing malfunctions, the bearing may sometimes be subjected to abnormal loads, causing the vehicle to stop abruptly. Considering such situations, the bearing requires exceptionally superior non-sintering properties. The method of embedding hard particles, as described in Patent Document 2, requires pre-mixing them into the cover material, and the mixing and manufacturing methods may impose limitations. Furthermore, appropriately mixing substances such as hard particles into the cover material to improve non-sintering properties under anticipated abnormal loads or malfunctions can lead to manufacturing limitations due to the properties of the base material and the additives. In addition, performance during normal use may also be limited.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2002-310158

[0009] Patent Document 2: Japanese Patent Application Publication No. 11-182549 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] The object of this invention is to provide a coating structure for a sliding bearing with excellent non-sintering properties. Furthermore, the object of this invention is to provide a coating structure for a sliding bearing that is easy to manufacture and cost-effective, as well as a method for manufacturing the same.

[0012] Technical solutions adopted to solve technical problems

[0013] One aspect of the present invention is to provide a sliding bearing having a base layer and a coating layer. The coating layer of the sliding bearing comprises at least two cover layers in the thickness direction and intermetallic compound layers located between adjacent cover layers. The intermetallic compound layers contain layered metal portions within an intermetallic compound matrix, the area of ​​which is 60% to 95% of the area of ​​the intermetallic compound layer.

[0014] According to a specific example, the coating consists of two cover layers and an intermetallic compound layer located between the two cover layers.

[0015] According to a specific example, the capping layer comprises a SnCu alloy, the intermetallic compound layer comprises a SnNi intermetallic compound and a SnNiCu intermetallic compound, and the metal portion comprises metallic Ni. Preferably, the SnNi intermetallic compound is Ni3Sn4, and the SnNiCu intermetallic compound is Sn5(CuNi)6.

[0016] According to a specific example, the thickness of the intermetallic compound layer is 1 to 10 μm, preferably 2 to 5 μm.

[0017] According to a specific example, the thickness of the cover layer is 1 to 30 μm, preferably 5 to 20 μm.

[0018] In one specific example, the base layer is an inner lining metal layer bonded with an inner liner, and the cover layer is disposed on the inner liner. The inner liner is preferably made of a copper-based alloy or an aluminum-based alloy.

[0019] According to a specific example, the sliding bearing further comprises a dam layer disposed between the inner liner and the outer coating. The dam layer preferably comprises at least one of nickel, cobalt, iron, copper, chromium, zinc, aluminum, and alloys thereof.

[0020] According to a specific example, the thickness of the dam layer is 0.5–10 μm, preferably 1–6 μm.

[0021] According to a specific example, the overall thickness of the coating is 5μm to 50μm.

[0022] The present invention also provides a method for manufacturing the above-described sliding bearing. This method includes a step of preparing a base layer, a step of attaching a first metal or alloy layer to the base layer, a step of attaching a second metal or alloy layer to the first layer, a step of attaching other layers of the first metal or alloy to the second layer, an optional step of attaching at least one group of second and first metal or alloy layers thereon, and a heat treatment step. In the heat treatment step, the attached layers are heated such that the metal atoms of the first metal or alloy layer reach a temperature capable of diffusion, causing the metal atoms of the first metal or alloy layer to diffuse into and react with the second metal or alloy layer, resulting in the formation of an intermetallic compound within the second metal or alloy while the second metal or alloy remains.

[0023] According to one specific example, the base layer is an inner lining metal layer to which the inner lining layer is bonded. According to one specific example, the manufacturing method further includes the step of attaching a dam layer to the bearing inner lining layer.

[0024] The invention and its numerous advantages will now be described in detail with reference to the accompanying drawings. The drawings show several non-limiting embodiments for illustrative purposes only. Attached Figure Description

[0025] Figure 1 The diagram shown is a schematic cross-sectional view of a sliding bearing, a specific example of the present invention.

[0026] Figure 2 The diagram shown is a schematic cross-sectional view of a sliding bearing, which is another specific example of the present invention.

[0027] Figure 3 This is a schematic diagram showing the extension of the metal part in a direction parallel to the sliding surface.

[0028] Figure 4 The figure shows a comparison of the time required for the sample of the present invention and the comparative material to sinter in the non-sintering test. Detailed Implementation

[0029] Figure 1The diagram shown is a schematic cross-sectional view of an example of the sliding bearing 1 of the present invention. The sliding bearing 1 comprises a base layer consisting of a liner metal 2 and an inner liner layer (bearing alloy layer) 3 bonded to the liner metal, an optional dam layer (diffusion shielding layer) 4 disposed on the inner liner layer, and a cover layer 5 on the dam layer. It has a structure consisting of a first cover layer 61, an intermetallic compound layer 7, and a second cover layer 62 stacked together. The surface of the first cover layer 61 forms a sliding surface 10. The intermetallic compound layer 7 contains metal portions 9 within an intermetallic compound matrix 8. The metal portions 9 are layered and extend substantially parallel to the sliding surface 10, and are divided by the intermetallic compound matrix 8. The area of ​​the layered metal portions 9 is 60% to 95% of the area of ​​the intermetallic compound layer 7. Preferably, the area of ​​the layered metal portions 9 is 70% to 90% of the area of ​​the intermetallic compound layer 7.

[0030] The lining metal 2 is not specifically specified in this invention and can be any suitable material such as steel, bronze, or aluminum alloy.

[0031] The inner lining 3 can be any suitable material, in practice either a copper alloy or an aluminum alloy.

[0032] If the sliding bearing 1 is used at high temperatures for an extended period, diffusion may occur between the inner liner 3 and the coating layer 5 due to thermal effects. Therefore, to prevent this diffusion, a dam layer 4 is preferably provided. The dam layer 4 comprises at least one of nickel, cobalt, iron, copper, chromium, zinc, aluminum, and their alloys, and is attached by any existing coating method. When the inner liner is a copper alloy, nickel is preferably used for the dam layer. In addition, the dam layer can be not only a metal or alloy, but also a substance containing an intermetallic compound or an intermetallic compound. In cases where an intermetallic compound is formed through heat treatment (described later), a multi-layer structure, such as a two-layer structure consisting of a metal or alloy layer and an intermetallic compound layer, can be formed.

[0033] The thickness of the dam layer 4 is typically in the range of 0.5 to 10 μm, preferably in the range of 1 μm to 6 μm. The thickness of the dam layer 4 is selected according to the purpose; for example, a thicker dam layer 4 can provide excellent bearing alloy properties, while a thinner dam layer 4 can provide excellent adaptability of the coating layer 5 during wear.

[0034] The coating layer 5 has a structure consisting of a first cover layer 61, an intermetallic compound layer 7, and a second cover layer 62 stacked together. Not limited to the examples described above, specific examples in this invention may also have three or more cover layers with intermetallic compound layers between them. Figure 2The diagram shown is a schematic cross-sectional view of another example of a sliding bearing 1 with a coating having three covering layers 61', 62', and 63' and two intermetallic compound layers 71 and 72. In this example, except for the coating layer 5, it has the configuration of a lining metal 2, an inner lining layer 3, a dam layer 4, and a coating layer 5' as described above.

[0035] Although not illustrated, a structure with four or more covering layers is clearly within the scope of this invention.

[0036] The multiple capping layers 6 in the coating layer 5 can have the same composition or different compositions. The capping layer 6 can contain at least one of tin, bismuth, lead, silver, indium, gold, antimony, aluminum, and their alloys. The capping layer 6 can be attached by any existing coating method.

[0037] The capping layer 6 may contain one or more soft particles selected from PTFE, fluorinated polymers, metal sulfides, metal fluorides, metal sulfates, graphite and other soft carbon particles, hexagonal boron nitride, layered silicates, titanium oxide, zinc oxide and lead oxide, and other particles exhibiting a hexagonal crystal structure. Furthermore, the capping layer 6 may contain one or more hard particles selected from metal oxides, borides, carbides, nitrides, sulfates and silicides, diamond, carbon nanotubes, graphene and other hard carbon particles, and other particles exhibiting a cubic crystal structure.

[0038] When multiple intermetallic compound layers 7 exist in the coating layer 5, the intermetallic compound matrix 8 can have the same composition or different compositions, and the metal part 9 can also have the same composition or different compositions. The intermetallic compound matrix 8 can be formed by heat treatment after the metal layer is attached using any existing coating method, and it requires at least two elements. One of them can be selected from tin, bismuth, lead, silver, indium, gold, antimony, and aluminum, and the other one or more elements can be selected from nickel, cobalt, zinc, silver, iron, copper, chromium, cadmium, and aluminum.

[0039] The intermetallic compound matrix 8 and / or the metal portion 9 may contain one or more soft particles selected from PTFE, fluorinated polymers, metal sulfides, metal fluorides, metal sulfates, graphite and other soft carbon particles, hexagonal boron nitride, layered silicates, titanium oxide, zinc oxide and lead oxide, and other particles exhibiting a hexagonal crystal structure. Furthermore, the intermetallic compound matrix 8 and / or the metal portion 9 may also contain one or more hard particles selected from metal oxides, borides, carbides, nitrides, sulfates and silicides, diamond, carbon nanotubes, graphene and other hard carbon particles, and other particles exhibiting a cubic crystal structure.

[0040] In the coating layer 5, the metal portion 9 of the intermetallic compound layer 7 can be selected from nickel, cobalt, zinc, silver, iron, copper, chromium, cadmium, aluminum, etc. The metal portion can be made of pure metal or an alloy.

[0041] The metal part 9 is in the form of layers or sheets, extending in a manner substantially parallel to the sliding surface 10, and is divided by intermetallic compounds. Figure 3 This is a schematic diagram showing the extension of the metal portion 9 in a direction parallel to the sliding surface 10. The layered metal portion 9 does not substantially coincide with the sliding surface 10 in the vertical direction. The area of ​​the layered metal portion 9 is 60% to 95% of the area containing the intermetallic compound layer 7, preferably 70% to 90%. In this document, the area of ​​the layered metal portion 9 refers to the area of ​​the metal portion 9 projected onto the sliding surface 10 when the metal portion 9 is projected onto the sliding surface 10. The area of ​​the intermetallic compound layer 7 is equal to the area of ​​the sliding surface (however, the area ratio is determined by cross-sectional observation as described below).

[0042] The area ratio of the layered metal portion is determined as follows: the cross-section of the sliding bearing is observed using an optical microscope or a scanning electron microscope (SEM), the length of the metal portion in the direction parallel to the sliding surface 10 is measured, and the ratio of its length to the length of the intermetallic compound layer 7 is calculated. This ratio is equal to the area ratio.

[0043] In the sliding bearing of the present invention, the coating layer 5 has a multi-layer structure. Under abnormal loads, the intermetallic compound layer 7 disperses due to the load, thus improving non-sintering properties. Even if the uppermost coating layer wears, the intermetallic compound can protect the lower layers below it from wear and sintering. At this time, it is considered that cracks may occur at the location of the intermetallic compound dividing the metal portion 9. Therefore, even if a large frictional force is applied to the intermetallic compound layer, the intermetallic compound layer will not peel off completely at the same time, but only locally. Since the position of the intermetallic compound dividing the metal portion 9 can be adjusted by the heat treatment time of the product, the dividing size of the intermetallic compound can be controlled. A suitable dividing size can be controlled according to the film thickness, material, number of layers, etc. of the coating layer 6. A suitable dividing size is preferably 0.1 μm to 30 μm, and more preferably 1 μm to 20 μm.

[0044] The segmentation size of the metal part 9 can be controlled according to the film thickness, material, number of layers, etc. required by the bearing application. In any case, by making the metal part 9 discontinuous, the intermetallic compound matrix 8 and the metal part 9 can be configured to interact, and excellent non-sintering properties can be achieved under abnormal loads.

[0045] This invention can fabricate a multilayered coated structure comprising an intermetallic compound layer 7 and a thin capping layer 6, further comprising an intermetallic compound matrix 8 and a metal portion 9 within the intermetallic compound layer 7. In this multilayered coated structure, the total thickness can be maintained the same as that of a single layer while the thickness of each layer is set relatively thin. Furthermore, the accumulation of plastic deformation under external loads can be significantly reduced, thereby improving the fatigue performance of the coating.

[0046] The thickness of the intermetallic compound layer 7 is in the range of 1 to 10 μm, preferably in the range of 2 to 5 μm. This structure can form the optimal metal portion 9, resulting in improved non-sintering properties of the bearing. Although the thickness of the metal portion 9 is not particularly limited, it is preferably 0.1 μm to 0.5 μm to achieve the above-mentioned effect. If the thickness of the metal portion 9 is too large, the intermetallic compound content will be insufficient, making it difficult to obtain the above-mentioned effect. Therefore, it is preferably less than 30% of the thickness of the intermetallic compound layer 7.

[0047] The thickness of each capping layer 6 is in the range of 1–30 μm, preferably in the range of 5–20 μm. The thickness of each capping layer 6 is selected according to the purpose. For example, a thicker capping layer 6 can obtain excellent adaptability to the sliding surface and foreign matter embedding. Conversely, a thinner capping layer 6 provides excellent fatigue resistance to the sliding surface. All capping layers 6 being relatively thick provides very excellent adaptability and foreign matter embedding. All capping layers 6 being relatively thin provides very excellent fatigue resistance. By multiplying to ensure the overall thickness of the coating layer 5, excellent adaptability and foreign matter embedding are further achieved.

[0048] The manufacturing method of the sliding bearing of the present invention will now be described. First, a base layer (preferably an inner lining metal layer with an adhesive liner) is prepared. Then, optionally, a dam layer is attached, followed by the attachment of a first metal or alloy layer. A second metal or alloy layer is attached to the first layer, and other layers of the first metal or alloy are attached to the second layer. Further, optionally, one or more groups of the second and first metal or alloy layers are attached thereto. The attachment method can be conventionally used methods such as electroplating or PVD. Afterward, the component is heat-treated. The aforementioned intermetallic compound is formed through heat treatment. The heat treatment causes metal atoms from the first metal or alloy layer to diffuse and react into the second metal or alloy layer, forming a metal compound. However, the second metal or alloy is not completely formed into an intermetallic compound; the heat treatment temperature and time are adjusted so that the second metal or alloy remains in a layered form, achieving an area ratio of 60% to 95% (as defined above).

[0049] Advantageously, the heat treatment is carried out at a temperature of 100°C to 250°C, preferably 150°C to 180°C. At higher temperatures, the crystal structure of the coating may change, affecting its tribological properties, while at lower thermal diffusion temperatures, the processing time becomes longer, increasing manufacturing costs. The duration of the thermal diffusion process is adjusted according to the composition of the coating, advantageously ranging from 2 to 60 hours, preferably 12 to 36 hours.

[0050] This invention can avoid the management of complex chemical processes by using a manufacturing method based on thermal diffusion, further reduce harmful internal stress, and achieve quality management and improved product performance.

[0051] Example

[0052] This article is merely an example to illustrate a specific preferred option.

[0053] On a 1.2 mm thick steel lining metal, CuPb22Sn (22% by mass Pb, 1.5% by mass Sn, and residual Cu), Ni, SnCu3 (3% by mass Cu, and residual Sn), Ni, and SnCu3 were sequentially deposited by electroplating to the thicknesses shown in Table 1. Subsequently, the component was subjected to two heat treatments at 165 °C for 8 hours each (totaling 16 hours), producing a [material name missing]. Figure 1 The sample of the sliding bearing with the structure shown is obtained. Through heat treatment, intermetallic compounds Sn5(CuNi)6 and Ni3Sn4 are formed by the reaction of SnCu3 with Ni. Although Ni is split, it remains in a layered form with a maximum thickness of approximately 0.5 μm. The area fraction of the Ni layer is approximately 80%. The thicknesses of each layer after heat treatment are shown in Table 2.

[0054] Table 1

[0055] Element Adhesion thickness First covering layer SnCu3 10μm Metal Department Ni 1μm intermetallic compounds - - Second Covering Layer SnCu3 10μm Dam layer Ni 3μm Inner lining CuPb22Sn 0.3mm

[0056] Table 2

[0057]

[0058] Sinterability test

[0059] To investigate the non-sintering properties, sintering tests were conducted on the samples from the embodiments of the present invention listed in Table 2 above. As a comparative material, a sample was prepared by sequentially attaching CuPb22Sn (inner lining layer): 0.3 mm, Ni (dam layer): 2 μm, and SnCu3 (coating layer): 20 μm onto a 0.7 mm thick steel lining metal using electroplating or the like. The comparative material differs from the present invention sample in that the coating layer is a single Sn-Cu alloy layer.

[0060] The sinterability test was conducted on a ring block testing machine under oil-controlled conditions. The test conditions are shown in Table 3. The test method is as follows.

[0061] Prepare with outer diameter inner diameter The test material, a flat plate, is placed beneath a rotating annular object material. Lubricating oil is supplied to the test material through an oil inlet located on the back side. A hydraulic device is installed on the lower surface of the test material, which applies pressure to the object material to measure the frictional torque and the temperature of the back side of the test material.

[0062] First, rotate the material without applying pressure, gradually increasing the rotational speed. When the rotational speed of the material reaches 2 m / s and the back surface temperature reaches 130°C, increase the load at a rate of 2 MPa every 2 minutes until the test load reaches 10 MPa. When the load of the material from the material to the test material reaches 10 MPa, stop supplying lubricating oil and begin the test. If the frictional torque exceeds 5 Nm or the back surface temperature exceeds 200°C, sintering is considered to have occurred.

[0063] Figure 4 The results of the sintering test are shown. The comparative materials sintered after approximately 40 to 75 minutes, while the sliding bearing of the present invention sintered after 103 to 140 minutes.

[0064] Table 3

[0065]

[0066] Symbol Explanation

[0067] 1: Sliding bearing

[0068] 2: Lining metal

[0069] 3: Inner Lining

[0070] 4: Dam layer

[0071] 5, 5': Covering layer

[0072] 6, 61, 62, 61', 62', 63': Overlay

[0073] 7, 71, 72: Containing intermetallic compound layers

[0074] 8: Intermetallic compound matrix

[0075] 9: Metal Department

[0076] 10: Sliding surface

Claims

1. A sliding bearing, It is a sliding bearing having a base layer and a coating layer, characterized in that, The coating layer consists of at least two capping layers and intermetallic compound layers located between adjacent capping layers. The intermetallic compound layer comprises layered metal portions within an intermetallic compound matrix, the area of ​​which is 60% to 95% of the area of ​​the intermetallic compound layer.

2. The sliding bearing as described in claim 1, wherein, The coating consists of two capping layers and an intermetallic compound layer located between the two capping layers.

3. The sliding bearing as described in claim 1 or claim 2, wherein, The capping layer comprises a SnCu alloy, the intermetallic compound matrix comprises a SnNi intermetallic compound and a SnNiCu intermetallic compound, and the metal portion comprises metallic Ni.

4. The sliding bearing as described in claim 3, wherein, The SnNi intermetallic compound is Ni3Sn4, and the SnNiCu intermetallic compound is Sn5(CuNi)6.

5. The sliding bearing as claimed in claim 1 or claim 2, wherein, The thickness of the intermetallic compound layer is 1–10 μm.

6. The sliding bearing as described in claim 5, wherein, The thickness of the intermetallic compound layer is 2–5 μm.

7. The sliding bearing as claimed in claim 1 or claim 2, wherein, The thickness of the covering layer is 1–30 μm.

8. The sliding bearing as claimed in claim 7, wherein, The thickness of the covering layer is 5–20 μm.

9. The sliding bearing as claimed in claim 1 or claim 2, wherein, The base layer is a lining metal layer with an inner lining layer bonded to it, and the cover layer is disposed on the inner lining layer.

10. The sliding bearing as claimed in claim 9, wherein, The inner lining is made of copper-based alloy or aluminum-based alloy.

11. The sliding bearing of claim 10, further comprising a dam layer disposed between the inner liner and the cover layer, the dam layer comprising at least one of nickel, cobalt, iron, copper, chromium, zinc, aluminum and alloys thereof.

12. The sliding bearing as claimed in claim 11, wherein, The thickness of the dam layer is 0.5–10 μm.

13. The sliding bearing as claimed in claim 12, wherein, The thickness of the dam layer is 1–6 μm.

14. The sliding bearing as claimed in claim 1 or claim 2, wherein, The overall thickness of the coating layer is 5μm to 50μm.

15. A method for manufacturing a sliding bearing, It is a method for manufacturing the sliding bearing according to any one of claims 1 to 14, comprising: The steps for preparing the base layer are as follows: The step of attaching the first metal or alloy layer. The step of attaching a second metal or alloy layer onto the first metal or alloy layer. The step of attaching other layers of the first metal or alloy onto the second metal or alloy layer. Optionally, the step of attaching at least one group of second and first metal or alloy layers thereon. The step of heat-treating the attached layer until reaching a temperature at which the metal atoms of the first metal or alloy layer can diffuse, causing the metal atoms to diffuse into and react with the second metal or alloy layer, thereby forming an intermetallic compound within the location of the second metal or alloy layer while the second metal or alloy remains.

16. The method for manufacturing a sliding bearing as described in claim 15, wherein, The base layer is a metal lining layer with an inner lining layer bonded to it.

17. The method of manufacturing a sliding bearing as claimed in claim 16, further comprising the step of attaching a dam layer to the inner liner.

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