sliding member

Abstract

The sliding member (10) of this invention has a backing metal portion (12) and a sliding alloy portion (11), wherein the sliding alloy portion (11) is disposed on one side of the backing metal portion (12) and has a sliding surface (13) on the opposite side of the backing metal portion (12). The sliding alloy portion (11) comprises: a matrix (14) which is composed of a Cu-based alloy containing 5% to 15% by mass of Sn and the remainder containing unavoidable impurities; 0.5% to 3% by mass of graphite particles (15); and 0.1% to 20% by mass of additive particles (16), wherein the additive particles (16) are formed of one or an alloy selected from Co, Mo, Cr, W, and thereof, and have a hardness of HV200 to HV500. When the area of ​​the graphite particle (15) in the first surface, which is perpendicular to the thickness direction of the sliding surface (13), is set as S1, and the area in the second surface, which is perpendicular to the first surface and parallel to the sliding surface (13), is set as S2, the ratio of S1:S2 is 1:1.5~2.5.

Description

Technical Field

[0001] This embodiment relates to a sliding member. Background Technology

[0002] Considering the environmental impact, the use of Pb is required to be avoided in sliding components. Therefore, Bi and Ni are added as additives to Cu-based sliding components (see Patent Documents 1 and 2). Cu-based sliding components with added Bi, as in Patent Document 1, tend to become brittle. While Cu-based sliding components with added Bi achieve sufficient performance at conventional circumferential speeds of around 0.5 m / s to 2.0 m / s, they suffer from insufficient mechanical properties, such as strength, at higher circumferential speeds. Furthermore, Cu-based sliding components with added Ni, as in Patent Document 2, tend to have reduced running-in performance. Therefore, Cu-based sliding components with added Ni have insufficient anti-seizure property at high circumferential speeds. Moreover, Cu-based sliding components with added hard particles, such as metal carbides, tend to easily damage the mating materials. Therefore, while hard particles are expected to be effective at low circumferential speeds, at high circumferential speeds, they can lead to increased friction, starting with damage to the mating materials. As a result, Cu-based sliding components with added hard particles exhibit insufficient anti-sticking properties under high circumferential speed conditions.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-54097;

[0006] Patent Document 2: Japanese Patent Application Publication No. 2003-269456. Summary of the Invention

[0007] The problem the invention aims to solve

[0008] Therefore, the object of the present invention is to provide a Cu-based sliding member that ensures mechanical properties and running-in performance even under high circumferential speed conditions, and has high anti-sticking and wear resistance.

[0009] Solution for solving the problem

[0010] To address the aforementioned problems, the sliding member of this embodiment includes a backing metal portion and a sliding alloy portion. The sliding alloy portion is disposed on one side of the backing metal portion and has a sliding surface on the opposite side of the backing metal portion. The sliding alloy portion comprises: a matrix composed of a Cu-based alloy containing 5% to 15% by mass of Sn and the remainder containing unavoidable impurities; 0.5% to 3% by mass of graphite particles; and 0.1% to 10% by mass of additive particles, wherein the additive particles are formed from one or an alloy selected from Co, Mo, Cr, and W, and have a hardness of HV200 to HV500. When the area of ​​the graphite particles in the first surface (a cross-section perpendicular to the sliding surface) is defined as S1, and the area of ​​the second surface (a cross-section perpendicular to the first surface and parallel to the sliding surface) is defined as S2, the ratio of S1 to S2 is 1:1.5 to 2.5.

[0011] In this embodiment, the sliding member has a Sn content in the Cu-based alloy. Therefore, the sliding member of this embodiment maintains the mechanical strength of the matrix while preventing the formation of intermetallic compounds at the grain boundaries of the crystals contained in the matrix. As a result, the sliding member of this embodiment ensures appropriate toughness of the matrix and guarantees mechanical properties and running-in performance. Furthermore, in the sliding member of this embodiment, the area S2 is larger than the area S1 of the graphite particles. That is, the sliding member of this embodiment contains graphite particles in a flattened state along the sliding surface within the matrix of the sliding alloy portion. This reduces the coefficient of friction and improves anti-sticking properties through the lubricating effect of the graphite particles along the sliding surface. Moreover, in the sliding member of this embodiment, the hardness of the additive particles contained in the sliding alloy portion is HV200 to HV500. Therefore, in this embodiment, the additive particles contained in the sliding alloy portion have low aggression towards the mating material that is the object of sliding. As a result, the sliding member of this embodiment is less likely to damage the mating material, reducing the increase in friction and solidification adhesion to the mating material that originates from such damage. Therefore, even under high circumferential speed conditions, mechanical properties and break-in performance can be ensured, and wear resistance can be improved while increasing anti-sticking properties. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing a cross-section of a sliding member according to one embodiment.

[0013] Figure 2 This is equivalent to Figure 1 A schematic diagram of the enlarged first surface of Part II.

[0014] Figure 3 For equivalent to Figure 2 A schematic diagram of the second surface at line III-III.

[0015] Figure 4 A schematic diagram illustrating the conditions for a wear resistance test of a sliding member according to one embodiment.

[0016] Figure 5 This is a schematic diagram illustrating the test piece used in a wear resistance test of a sliding member according to one embodiment.

[0017] Figure 6 A schematic diagram of a test piece used in a test to demonstrate the mechanical strength of a sliding member according to one embodiment.

[0018] Figure 7 A schematic diagram illustrating the conditions for an anti-sticking test of a sliding member according to one embodiment.

[0019] Figure 8 A schematic diagram illustrating the results of an embodiment and comparative example of a sliding member of one implementation.

[0020] Figure 9 A schematic diagram illustrating the results of an embodiment and comparative example of a sliding member of one implementation.

[0021] Figure 10 A schematic diagram illustrating the results of an embodiment and comparative example of a sliding member of one implementation. Detailed Implementation

[0022] The sliding member of this embodiment will now be described based on the accompanying drawings. Furthermore, in this specification, "X~Y," which refers to a numerical range, means a range including the values ​​of X and Y as its two ends.

[0023] like Figure 1 As shown, the sliding member 10 of this embodiment has a sliding alloy portion 11 and a backing metal portion 12. The sliding alloy portion 11 is provided on one side of the backing metal portion 12. The sliding alloy portion 11 has a sliding surface 13 on the surface opposite to the backing metal portion 12. The sliding member 10 slides with a mating material (not shown) at this sliding surface 13. The sliding member 10 of this embodiment is used, for example, as a piston slide of a high-pressure pump, a valve plate, etc., and is used in a flat plate shape. Furthermore, the plate thickness of the sliding member 10 is about a few mm to tens of mm, and the thickness of the sliding alloy portion 11 is less than a few mm.

[0024] Sliding alloy part 11 Figure 2The diagram shows a matrix 14, graphite particles 15, and additive particles 16. The matrix 14 is formed of a Cu-based alloy containing 5% to 15% by mass Sn relative to the entire sliding alloy portion 11, with the remainder containing unavoidable impurities. The Sn content in the sliding alloy portion 11 is preferably 12% by mass or less. When the Sn content in the sliding alloy portion 11 is less than 5% by mass, the effect of adding Sn to the matrix 14 becomes insufficient, and the strength of the matrix 14 decreases. As a result, the sliding alloy portion 11 has insufficient load-bearing capacity during sliding. On the other hand, when the Sn content in the sliding alloy portion 11 is more than 15% by mass, intermetallic compounds are easily formed at the grain boundaries of the crystals contained in the matrix 14. The intermetallic compounds formed at the grain boundaries make the matrix 14 brittle and reduce its toughness. Therefore, the Sn content in the sliding alloy portion 11 is preferably set to 15% by mass or less, and more preferably 12% by mass or less.

[0025] Graphite particles 15 and additive particles 16 are dispersed in the matrix 14 of the sliding alloy portion 11. The sliding alloy portion 11 contains 0.5% to 3% by mass of graphite particles 15. More preferably, the sliding alloy portion 11 contains 1% to 2% by mass of graphite particles 15. The graphite particles 15 are granular. Here, the granular graphite particles 15 in this embodiment also include flat, scaly shapes. That is, the granular graphite particles 15 include not only three-dimensional shapes having length in three axes, but also shapes with a length in one axis that is sufficiently small compared to the lengths in the other two axes, i.e., scaly shapes.

[0026] The sliding alloy portion contains 0.1% to 20% by mass of additive particles 16. More preferably, the sliding alloy portion contains 0.1% to 10% by mass of additive particles 16. The additive particles 16 are in the form of fine granules. The additive particles 16 are formed from an alloy selected from Co, Mo, Cr, and W, or with Co as the primary component. That is, the additive particles 16 are formed from elemental metals of Co, Mo, Cr, and W, or compounds with Co, Mo, Cr, and W as the first element. The hardness of the additive particles 16 is HV200 to HV500. During the processing of the sliding alloy portion 11, the additive particles 16 formed from these metals and alloys do not form intermetallic compounds with the Cu-Sn alloy. Therefore, the reduction in hardness of the sliding alloy portion 11 can be suppressed. Furthermore, by setting the hardness of the additive particles 16 to HV200 to HV500, the aggression towards the mating material is reduced. As a result, the sliding member 10 is less likely to damage the mating material, reducing the increase in friction and solidification adhesion to the mating material that would otherwise result in such damage. In particular, the metal or compound selected as the material for the additive particles 16 differs from the composition of Cu-Sn, the main component of the sliding alloy portion 11, and the composition of the sliding mating material. Therefore, the additive particles 16 also reduce transfer and solidification adhesion to the mating material.

[0027] Graphite particles 15 are dispersed in the matrix 14 within the sliding alloy portion 11. Here, in the sliding alloy portion 11, a cross-section perpendicular to the sliding surface 13 is designated as a first surface, and a cross-section perpendicular to this first surface is designated as a second surface. That is, as... Figure 2 As shown, the cross-section of the sliding alloy portion 11 cut perpendicularly to the sliding surface 13 in the thickness direction is designated as the first surface, such as... Figure 3 As shown, the cross-section perpendicular to the first surface and parallel to the sliding surface 13 is designated as the second surface. The graphite particles 15 are flaky particles and therefore have a flat shape. In this embodiment, the area S1 of the cross-section in the first surface and the area S2 of the cross-section in the second surface of the graphite particles 15 have a relationship of S1∶S2=1∶1.5~2.5.

[0028] In other words, in this embodiment, the graphite particles 15 contained in the sliding alloy portion 11 are as follows: Figure 2 The section shown is thin and small in the thickness direction, in contrast to, as Figure 3 The cross-section shown is large along the direction of the sliding surface 13. In other words, the sliding alloy portion 11 of this embodiment contains thin, flake-like graphite particles 15 in a layered manner, approximately parallel to the sliding surface 13. Therefore, the graphite particles 15 contained in the sliding alloy portion 11, as shown in the diagram... Figure 2 The first surface shown is a smaller cross-section, in contrast to the smaller cross-section shown in the image. Figure 3The second surface shown has a larger cross-section. The ratio of area S1 to area S2 is calculated using the sum of the cross-sectional areas of graphite particles 15 in any first surface of the same sliding member 10 and the sum of the cross-sectional areas of graphite particles 15 in any second surface. Furthermore, as long as the first surface is a cross-section perpendicular to the second surface, it can be used as, for example... Figure 3 It can be set at any position, like the AA section or BB section. That is, Figure 3 The second side shown is just one example. As long as the graphite particles 15 contained in the sliding alloy part 11 are in a state of being approximately parallel to the sliding surface 13, the length direction of the graphite particles 15 observed from the sliding surface 13 side can be any direction.

[0029] When S1:S2 is less than 1:1.5, there is insufficient graphite particles 15 in the sliding surface 13 to help reduce friction with the mating material. That is, when S1:S2 is less than 1:1.5, the area of ​​graphite particles 15 exposed on the sliding surface 13 becomes smaller. Therefore, the contribution of graphite particles 15 as a solid lubricant decreases, and anti-sticking properties decrease. Furthermore, when S1:S2 exceeds 1:2.5, the thickness of graphite particles 15 becomes too small, the bonding force with the matrix 14 decreases, and even if exposed on the sliding surface 13, wear occurs quickly. That is, when the thickness of graphite particles 15 becomes too small, the area of ​​graphite particles 15 in the second surface parallel to the sliding surface 13 becomes relatively large. Therefore, the bonding force between the matrix 14 containing the graphite particles 15 in the thickness direction is relatively reduced, and the graphite particles 15 become easier to detach from the matrix 14. As a result, the contribution of graphite particles 15 as a solid lubricant decreases, and wear resistance decreases. Therefore, the ratio of area S1 to area S2 is set as S1∶S2=1∶1.5~2.5.

[0030] In this manner, the sliding alloy portion 11 contains graphite particles 15. The graphite particles 15 are exposed on the sliding surface 13 within the sliding alloy portion 11. The area R occupied by the graphite particles 15 on the sliding surface 13 is 2% to 20%. This area ratio R is calculated as R = B / A × 100 when an arbitrary observation area is defined in the sliding surface 13, the area of ​​this observation area is designated as the area A, and the area of ​​the graphite particles 15 contained in this observation area is designated as the graphite area B. A larger area ratio R indicates a larger area of ​​graphite particles 15 exposed on the sliding surface 13. When the area ratio R becomes too large, and the area occupied by the graphite particles 15 on the sliding surface 13 increases, the proportion of the substrate 14 of the sliding alloy portion 11 in the sliding surface 13 decreases. Therefore, the sliding alloy portion 11 leads to a decrease in wear resistance and mechanical strength.

[0031] On the other hand, when the area ratio R becomes too small and the area occupied by the graphite particles 15 in the sliding surface 13 becomes smaller, the proportion of graphite particles 15 in the sliding surface 13 decreases. Therefore, the contribution of the graphite particles 15 as a solid lubricant decreases, and the anti-sticking property decreases. The area ratio R of the graphite particles 15 varies depending on the content of graphite particles 15 contained in the sliding alloy portion 11. That is, the area ratio R is related to the content of graphite particles 15. When the content of graphite particles 15 in this embodiment is the lower limit, i.e., 0.5% by mass, the area ratio R is approximately 2%. On the other hand, when the content of graphite particles 15 in this embodiment is the upper limit, i.e., 3% by mass, the area ratio R is approximately 20%. Therefore, the area ratio R is preferably set to 2% to 20%, and more preferably set to 5% to 11%.

[0032] Next, the manufacturing method of the sliding member 10 of this embodiment will be described.

[0033] In a mixer, powders of Cu-Sn alloy (which forms the matrix 14), graphite particles 15, and additive particles 16 are mixed. The Cu-Sn alloy powder is preferably irregularly shaped rather than spherical. On the other hand, the additive particles 16 are approximately spherical. The graphite particles 15 are flake-shaped particles with an average particle size of 50 μm to 150 μm. The particle size of the graphite particles 15 is determined, for example, by sieving. In this embodiment, the graphite particles 15, Cu-Sn alloy powder, and additive particles 16 are pre-mixed in a mixer to ensure uniform mixing without deviation. The mixed powder is then dispersed on a steel plate (not shown) that forms the backing metal portion 12. To ensure adhesion between the steel plate and the Cu-Sn alloy that forms the sliding alloy portion 11, Cu plating is preferably performed, for example. The powder dispersed on the steel plate and the steel plate are then sintered together in a furnace under a reducing atmosphere. Thus, the steel plate that forms the backing metal portion 12 and the layer that forms the sliding alloy portion 11 are formed as a single primary product. At this time, since the powder used as raw material is pre-mixed as described above, the graphite particles 15 and additive particles 16 are dispersed without deviation in the Cu-Sn alloy matrix 14. The primary product generated by a single sintering is rolled. Through this rolling, the orientation of the graphite particles 15 contained in the layer forming the sliding alloy portion 11 within the matrix 14 is controlled, and the S1:S2 ratio is controlled as described in this embodiment. A second sintering is performed on the primary product after rolling. Through this second sintering, the sliding alloy portion 11 is given a running-in property.

[0034] Next, an embodiment of this implementation will be described.

[0035] (Calculation of S1 and S2)

[0036] The areas S1 in the first surface and S2 in the second surface are calculated based on images obtained by taking pictures of the ground cross-section using a digital microscope. Specifically, the matrix 14 and graphite particles 15 are extracted from the pictures. Then, image analysis is used to calculate the sum of the areas S1 of the graphite particles 15 in the first surface and the sum of the areas S2 of the graphite particles 15 in the second surface.

[0037] (Evaluation of wear resistance)

[0038] Abrasion resistance was tested using a load-varying friction and abrasion testing machine (HEIDON). Figure 4 The conditions shown are used for evaluation. The mating material is SUS304. The abrasion resistance test is passed, as shown... Figure 5 As shown, test piece 20 develops a slip mark 21 due to contact with a mating material (not shown). The wear amount is measured based on the cross-sectional area in a section perpendicular to the slip mark 21. The wear amount is measured, for example, by... Figure 5 The cross-sectional areas of the sliding marks 21 in the A1-A1, A2-A2, and A3-A3 sections shown are used, and the average value of these cross-sectional areas is calculated. The locations for measuring this wear amount are set as three arbitrary points relative to one sliding mark 21.

[0039] (Evaluation of mechanical strength)

[0040] Mechanical strength is evaluated using tensile strength. For example... Figure 6 As shown, the tensile strength of the embodiments and comparative examples was determined using test piece 30. Test piece 30 is a component in which a portion of the backing metal portion 32 is removed from the integral sliding alloy portion 31 and the backing metal portion 32, leaving a portion of the sliding alloy portion 31 remaining. The tensile strength is determined based on the maximum tensile load at which the sliding alloy portion 31 breaks when a tensile load is applied to both ends of the test piece 30.

[0041] (Evaluation of anti-bite adhesion)

[0042] Anti-sticking test was performed using a ring-on-disk friction tester. Figure 7 The evaluation is conducted under the conditions shown. Specifically, the anti-bite adhesion is assessed by... Figure 7 Under the conditions shown, a load was applied, and the maximum surface pressure without bite adhesion was measured. The evaluation was based on this maximum surface pressure. This bite adhesion resistance evaluation was conducted under conditions where the circumferential speed was set to 8.0 m / s, a relatively high value compared to previous methods.

[0043] (Evaluation Results)

[0044] The evaluation results of the embodiments and comparative examples are shown in Figures 8-10 .

[0045] Each embodiment and comparative example was evaluated based on "Comparative Example 1," a conventional product containing Pb in the sliding alloy portion 11. Specifically, the "mechanical strength," "anti-sticking," and "wear resistance" in "Comparative Example 1" were set to "1," and the evaluation was based on the degree to which each embodiment and comparative example improved or decreased compared to this "reference example." For example, when the "mechanical strength" in "Comparative Example 1" was "150 MPa," then the "mechanical strength" of the embodiment or comparative example that became "1.1" was expressed as "165 MPa." The evaluation of "anti-sticking" and "wear resistance" was also the same. Furthermore, the "150 MPa" of "mechanical strength" in "Reference Example 1" above is an example.

[0046] Figure 8 Examples 1 to 3 illustrate the effect of Sn content in the matrix 14 of the sliding alloy portion 11. In Examples 1 to 3, the S1 to S2 ratio of graphite particles was S1:S2 = 1:1.78. Furthermore, in Examples 1 to 3, 3.15% by mass of W was included as additive particles 16. Consequently, the hardness of the additive particles 16 included in the sliding alloy portion 11 from Examples 1 to 3 was HV400 to HV500. In these Examples 1 to 3, compared to Comparative Example 1, wear resistance, mechanical strength, and anti-sticking properties were maintained or improved. In particular, Example 3, with a Sn content of 11% by mass, showed a significant improvement in wear resistance, mechanical strength, and anti-sticking properties.

[0047] Examples 3 to 6, and Comparative Examples 2 to 5, evaluated the effect of the content of graphite particles 15 in the matrix 14 of the sliding alloy portion 11. In Example 4, Mo was added to replace W in Example 3 as the additive particle 16. Example 5 represents the lower limit of the graphite particle 15 content, and Example 6 represents the upper limit of the graphite particle 15 content. The graphite particle 15 content in Comparative Example 2 was below the lower limit, while the graphite particle 15 content in Comparative Example 3 was above the upper limit. Furthermore, Comparative Example 4 was an example where no graphite particles 15 were present but additive particles 16 were added, and Comparative Example 5 was an example where graphite particles 15 were present but additive particles 16 were not. From these examples, it can be seen that by adjusting the content of graphite particles 15 in the matrix 14 of the sliding alloy portion 11 and the ratio of S1 to S2, and appropriately adding additive particles 16, the wear resistance, mechanical strength, and anti-sticking properties of the sliding member 10 are improved.

[0048] Figure 9Examples 7-9 and Comparative Examples 6-7 illustrate the effects of the material of the additive particles 16 contained in the matrix 14 of the sliding alloy section 11. In Examples 7-9 and Comparative Examples 6-7, the Sn content in the matrix 14 was set to 11.00% by mass, and the graphite particle content was set to 0.50% by mass. Example 7 contained Mo as the additive particle 16, Example 8 contained a Co compound, namely CoS, as the additive particle 16, and Example 9 contained a Cr compound, namely CrN, as the additive particle 16. The hardness of these additive particles 16 was all HV200 to HV500. On the other hand, Comparative Example 6 contained a Mo compound, namely Mo2C, as the additive particle 16, but its hardness was HV1000 to HV1200. Furthermore, Comparative Example 7 contained ZnO as the additive particle 16, and its hardness was less than HV200. It can be seen from this that by appropriately selecting the material of the additive particles 16 contained in the matrix 14 in the sliding alloy part 11 and appropriately setting its hardness, the wear resistance, mechanical strength and anti-sticking properties of the sliding member 10 are improved.

[0049] Figure 10 Examples 10 and 11 illustrate the effect of the content of additive particles 16 in the matrix 14 of the sliding alloy portion 11. In Example 10, the Sn content in the matrix 14 was set to 11.00% by mass, and the graphite particle content was set to 1.50% by mass. Furthermore, Example 10 contained 0.10% by mass of W as additive particles 16, and Example 11 contained 10.00% by mass of W. From this, it can be seen that as long as the content of additive particles 16 in the sliding alloy portion 11 is in the range of 0.1% by mass to 20% by mass, it will not have an adverse effect on the improvement of wear resistance, mechanical strength, and anti-sticking properties. In particular, considering the ease of manufacturing, the content of additive particles 16 in the sliding alloy portion 11 is preferably 10% by mass or less.

[0050] As described above, the sliding member 10 of this embodiment is configured to contain Sn in the Cu-based alloy that forms the sliding alloy portion 11. Therefore, the sliding alloy portion 11 maintains the mechanical strength of the substrate 14 while preventing the formation of intermetallic compounds at the grain boundaries of the crystals contained in the substrate 14. As a result, the sliding member 10 ensures appropriate toughness of the substrate 14, and also ensures mechanical properties and running-in comfort.

[0051] Furthermore, in the sliding member 10 of this embodiment, the area S2 is larger than the area S1 of the graphite particles 15. That is, the sliding member 10 contains graphite particles 15 in a flattened state along the sliding surface 13 within the substrate 14 of the sliding alloy portion 11. As a result, the coefficient of friction is reduced and anti-sticking properties are improved through the lubricating effect of the graphite particles along the sliding surface 13. Furthermore, the hardness of the additive particles 16 included in the sliding alloy portion 11 of the sliding member 10 is HV200 to HV500. Therefore, the additive particles 16 included in the sliding alloy portion 11 have low aggression towards the mating material that is the object of sliding. As a result, the sliding member 10 of this embodiment is less likely to damage the mating material, reducing the increase in friction and solidification adhesion to the mating material that originates from such damage. Therefore, even under high circumferential speed conditions, mechanical properties and running-in performance can be ensured, and wear resistance can be improved while simultaneously increasing anti-sticking properties.

[0052] The present invention described above is not limited to the above-described embodiments, and can be applied to various embodiments without departing from its spirit.

Claims

1. A sliding member having a backing metal portion and a sliding alloy portion, the sliding alloy portion being disposed on one side of the backing metal portion and having a sliding surface on the opposite side of the backing metal portion. The sliding alloy portion includes: The matrix is ​​composed of a Cu-based alloy containing 5% to 15% Sn by mass, with the remainder containing unavoidable impurities. 0.5% to 3% by mass of graphite particles; and 0.1% to 10% by mass of additive particles, said additive particles being formed from one selected from Co, Mo, Cr, W or alloys thereof, and having a hardness of HV200 to HV500. When the area of ​​the graphite particle in the first surface (the cross-section perpendicular to the sliding surface) is defined as S1, and the area in the second surface (the cross-section perpendicular to the first surface and parallel to the sliding surface) is defined as S2, the graphite particle's surface area is... S1∶S2=1∶1.5~2.

5.

2. The sliding member according to claim 1, wherein, The Sn contained in the sliding alloy portion is less than 12% by mass.

3. The sliding member according to claim 1, wherein, The sliding alloy portion contains 1% to 2% by mass of the graphite particles.

4. The sliding member according to claim 1, wherein, The area ratio of the graphite particles in the sliding surface is 2% to 20%.

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