Sliding components and their manufacturing methods

Abstract

The sliding member (10) of this embodiment has a Sn alloy layer (11) and an Fe-based inner lining metal layer (12). In any observation section (20) at the interface (21) between the Sn alloy layer (11) and the inner lining metal layer (12), the total length of the Sn alloy parent phase (13) contained in the Sn alloy layer (11) in contact with the inner lining metal layer (12) is 30% or more relative to the total length of the interface (21). In the observation section (20), the total area of ​​the intermetallic compound (14) is 40% or more and 70% or less relative to the total area of ​​the Sn alloy layer (11). When multiple fields of view of the same area are arbitrarily extracted from the cross section of the Sn alloy layer (11), the difference D = A - B between the area percentage A% of the first field of view with the largest area percentage of the intermetallic compound (14) and the area percentage B% of the second field of view with the smallest area percentage of the intermetallic compound (14) is within 20%.

Description

Technical Field

[0001] This embodiment relates to a sliding component and a method for manufacturing the same. Background Technology

[0002] The sliding member, for example, has a Sn-based Sn alloy layer on the surface of an Fe-based lining metal layer. To improve fatigue resistance, elements such as Cu and Sb, which form intermetallic compounds with Sn, the parent phase of the Sn alloy layer, are added to the Sn alloy that slides with the target member. On the other hand, excessive addition of Cu and Sb can lead to segregation of Cu5Sn and other brittle elements near the interface with the lining metal layer. Therefore, excessive addition of Cu and Sb can reduce the bonding strength between the lining metal layer and the Sn alloy layer. Therefore, in the case of Patent Document 1, the amount of Cu added is set to less than 1 to 3% by mass. As a result, in Patent Document 1, the Cu5Sn6 and SbSn, which are intermetallic compounds, are miniaturized, and the segregation of Cu5Sn6 is reduced. As a result, in Patent Document 1, both the fatigue resistance of the sliding member and the bonding strength between the lining metal layer and the Sn alloy layer are improved.

[0003] However, in order to achieve miniaturization of the intermetallic compounds in the Sn alloy layer while reducing segregation, Patent Document 1 requires the addition of Cd and Be. The use of these Cd and Be is subject to control when considering their environmental impact.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 50-1687. Summary of the Invention

[0007] The problem the invention aims to solve

[0008] Therefore, the object of the present invention is to provide a sliding member with high fatigue resistance and bonding strength between the Sn alloy layer and the inner lining metal layer while excluding substances with high environmental impact, and a method for manufacturing the same.

[0009] Solution for solving the problem

[0010] To solve the above problems, the sliding member of this embodiment has a Sn alloy layer and an Fe-based lining metal layer. The Sn alloy layer contains a Sn alloy matrix phase and a Sn-based intermetallic compound dispersed in the Sn alloy matrix phase. The Fe-based lining metal layer has the Sn alloy layer disposed on at least one end face.

[0011] In any observation section at the interface between the Sn alloy layer and the inner lining metal layer, the total length of the Sn alloy parent phase contained in the Sn alloy layer in contact with the inner lining metal layer is more than 30% of the total length of the interface. In the observation section, the total area of ​​the intermetallic compounds is more than 40% and less than 70% of the total area of ​​the Sn alloy layer. When multiple fields of view of the same area are arbitrarily extracted from the cross section of the Sn alloy layer, the difference D = AB between the area percentage A% of the first field of view with the largest area percentage of the intermetallic compounds and the area percentage B% of the second field of view with the smallest area percentage of the intermetallic compounds is less than 20%.

[0012] The inventors discovered that the contact state between the Sn alloy matrix phase of the Sn alloy layer and the lining metal layer at the interface between the Sn alloy layer and the lining metal layer, as well as the dispersion state of the intermetallic compounds contained in the Sn alloy layer, affects the bonding strength between the Sn alloy layer and the lining metal layer. In this embodiment, by specifically defining the contact state between the Sn alloy matrix phase and the lining metal layer and the dispersion state of the intermetallic compounds as described above, the bonding strength between the Sn alloy layer and the lining metal layer can be ensured without compromising the fatigue resistance of the Sn alloy layer. Furthermore, in this embodiment, it is not necessary to add environmentally harmful substances such as Cd and Be. Therefore, it is possible to improve both fatigue resistance and the bonding strength between the Sn alloy layer and the lining metal layer while eliminating substances with high environmental impact.

[0013] Furthermore, the manufacturing method of the sliding member in this embodiment includes an irradiation step, an insertion step, and an alloy layer formation step. In the irradiation step, a laser is irradiated onto one end face of the inner lining metal layer. In the insertion step, an alloy material for forming the Sn alloy layer is inserted at the focal point of the laser irradiated in the irradiation step. In the alloy layer formation step, the irradiated laser melts the alloy material inserted in the insertion step onto the surface of the inner lining metal layer, and the alloy material formed by the melting is bonded to the inner lining metal layer, thereby depositing the Sn alloy layer onto the inner lining metal layer.

[0014] In this embodiment, a Sn alloy layer is deposited onto the surface of the liner metal layer via laser cladding. This controls the formation of intermetallic compounds dispersed in the Sn alloy matrix phase at the interface between the Sn alloy layer and the liner metal layer. Therefore, fatigue resistance and adhesion between the Sn alloy layer and the liner metal layer can be improved while eliminating environmentally damaging substances. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view illustrating a sliding member according to one embodiment.

[0016] Figure 2This is a schematic diagram showing the structure of the Sn alloy layer of a sliding member according to one embodiment.

[0017] Figure 3 This is a schematic cross-sectional view showing an observation section of a sliding member according to one embodiment.

[0018] Figure 4 This is a schematic cross-sectional view showing an observation section of a sliding member according to one embodiment.

[0019] Figure 5 This is a schematic cross-sectional view showing an observation section of a sliding member according to one embodiment.

[0020] Figure 6 This is a schematic cross-sectional view showing the Sn alloy layer of a sliding member according to one embodiment.

[0021] Figure 7 This is a schematic diagram illustrating the manufacture of a sliding member using one embodiment of laser cladding.

[0022] Figure 8 This is a schematic diagram illustrating the manufacture of a sliding member using one embodiment of centrifugal casting.

[0023] Figure 9 This is a schematic diagram illustrating the composition of the materials used in a sliding member according to one embodiment.

[0024] Figure 10 This is a schematic diagram illustrating the conditions for laser cladding used in the manufacture of a sliding member according to one embodiment.

[0025] Figure 11 This is a schematic diagram illustrating the test results of an embodiment of a sliding member.

[0026] Figure 12 This is a schematic diagram showing the test results of a comparative example of a sliding member.

[0027] Figure 13 This is a schematic diagram illustrating the test results of an embodiment of a sliding member.

[0028] Figure 14 This is a schematic diagram illustrating the test results of an embodiment of a sliding member.

[0029] Figure 15 This is a schematic diagram illustrating the test results of an embodiment of a sliding member. Detailed Implementation

[0030] Hereinafter, one embodiment of the sliding member will be described based on the accompanying drawings.

[0031] like Figure 1 As shown, the sliding member 10 has a Sn alloy layer 11 and a lining metal layer 12. The Sn alloy layer 11 is formed of a Sn-based alloy, such as... Figure 2 As shown, the Sn alloy matrix 13 and intermetallic compound 14 are included. The Sn alloy matrix 13 is formed from the Sn alloy constituting the Sn alloy layer 11. The intermetallic compound 14 is formed as a compound of various elements constituting the Sn alloy layer 11 in particulate form and dispersed in the Sn alloy matrix 13. The inner lining metal layer 12 is formed from an Fe-based alloy, such as steel or carbon steel, with Fe as the main component. A sliding surface 15 (not shown) is formed on the opposite side of the inner lining metal layer 12 of the Sn alloy layer 11, which slides with the object member 10. In addition, the sliding member 10 may also have other layers, such as a cover layer, on the end face (surface) of the Sn alloy layer 11 opposite to the inner lining metal layer 12. For example, the sliding member 10 may also have an intermediate layer and a cover layer (not shown) on the sliding surface 15 side of the Sn alloy layer 11. The Vickers hardness of the Sn alloy layer 11 is 38 HV or higher. In this way, by increasing the hardness of the Sn alloy layer 11, the fatigue resistance of the sliding member 10 can be improved.

[0032] The Sn alloy layer 11 comprises 3.0 to 12% by mass of Sb, 4.0 to 18% by mass of Cu, and the remainder being Sn containing unavoidable impurities. Furthermore, the Sn alloy layer 11 may also contain one or more metals selected from Bi, Ag, Zn, Cr, and Ba. The Sn alloy layer 11 can contain a maximum of 5.0% by mass of Bi, a maximum of 10% by mass of Ag, a maximum of 10% by mass of Zn, a maximum of 0.5% by mass of Cr, and a maximum of 0.5% by mass of Ba. Thus, the Sn alloy layer 11 contains various compounds such as Sn-Sb, Sn-Ag, and Sn-Cu as intermetallic compounds 14 in the Sn alloy matrix phase 13. The intermetallic compound 14 is not limited to compounds of two elements as in the example, but may be compounds of three or more elements. Additionally, Fe-Sn compounds, such as those from Sn contained in the Sn alloy layer 11 and Fe contained in the lining metal layer 12, are not included in the intermetallic compounds of this embodiment.

[0033] The sliding member 10 is as follows Figure 1 and Figure 3An arbitrary observation section 20 is provided. The observation section 20 is set in a section cut along the thickness direction of the sliding member 10, for example, within an arbitrary range from approximately several μm × several μm to approximately several mm × several mm. In this observation section 20, the thickness direction is designated as the Y direction, and the direction perpendicular to the thickness is designated as the X direction. In the observation section 20, the interface 21 between the Sn alloy layer 11 and the inner lining metal layer 12 extends along the X direction. The total length of the observation section 20 in the X direction, i.e., the distance between X1 and X2, coincides with the total length L of the interface 21 between the Sn alloy layer 11 and the inner lining metal layer 12. On the other hand, the Sn alloy layer 11 contains an intermetallic compound 14. Therefore, there are portions where the Sn alloy matrix phase 13 of the Sn alloy layer 11 contacts the inner lining metal layer 12, and portions where the intermetallic compound 14 contacts the inner lining metal layer 12. The length of the portion of the Sn alloy parent phase 13 in contact with the inner lining metal layer 12 in the X direction is denoted as Lxn, where n is a natural number. The total length Lx of the portion of the Sn alloy parent phase 13 in contact with the inner lining metal layer 12 is Lx = Lx1 + Lx2 + Lx3 + ... + Lxn. The length Lxn of the portion of the Sn alloy parent phase 13 in contact with the inner lining metal layer 12 is determined by image analysis of an image taken at the observation section 20. Hereinafter, for ease of explanation, ... Figure 3 The example shown is n=4.

[0034] exist Figure 3 In the example shown, the total length Lx of the portion where the Sn alloy parent phase 13 contacts the inner lining metal layer 12 is Lx = Lx1 + Lx2 + Lx3 + Lx4. In this embodiment, the total length Lx of the contact between the Sn alloy parent phase 13 and the inner lining metal layer 12 is 30% or more relative to the total length L of the interface 21. That is, the contact ratio Lx / L is Lx / L×100≥30 (%). Thus, in this embodiment, at the interface 21 between the Sn alloy layer 11 and the inner lining metal layer 12, the portion of the sliding member 10 where the Sn alloy parent phase 13 contacts the inner lining metal layer 12 is 30% or more of the total length L of the interface 21. The bonding force between the Sn alloy layer 11 and the inner lining metal layer 12 is ensured at the portion where the Sn alloy parent phase 13 contacts the inner lining metal layer 12. In the case of the sliding member of this embodiment, the Sn alloy parent phase 13 and the inner lining metal layer 12 are in contact at the interface 21 over a region of more than 30% of the total length L. This ensures a sufficient total length between the Sn alloy layer 11 and the inner lining metal layer 12 to guarantee the bonding force.

[0035] Furthermore, in the sliding member 10 of this embodiment, in any observation section 20, the total area of ​​the intermetallic compound 14 is 40% or more and 70% or less relative to the total area of ​​the Sn alloy layer 11. That is, the ratio of the total area Sm of the intermetallic compound 14 included in the observation section 20 to the total area S of the Sn alloy layer 11 in the observation section 20, i.e., Sm / S, is 40% ≤ Sm / S × 100 ≤ 70%. The total area Sm of the intermetallic compound 14 is determined by image analysis of the image of the observation section 20, similar to the length Lxn. The greater the proportion of the area of ​​the intermetallic compound 14 in the Sn alloy layer 11, i.e., the greater the value of Sm / S, the more it contributes to improving the fatigue resistance of the sliding member 10. On the other hand, when the ratio Sm / S of the intermetallic compound 14 in the Sn alloy layer 11 becomes too large, the total length Lx of the contact between the Sn alloy parent phase 13 and the inner lining metal layer 12 decreases, and the bonding force between the Sn alloy layer 11 and the inner lining metal layer 12 decreases. By keeping the ratio Sm / S in the range of 40% ≤ Sm / S × 100 ≤ 70%, the sliding member 10 can achieve both improved fatigue resistance and improved bonding force between the Sn alloy layer 11 and the inner lining metal layer 12.

[0036] Furthermore, in the sliding member 10 of this embodiment, the cross-section 20 is observed as follows: Figure 4 This illustrates the arbitrary extraction of multiple fields of view with the same area. Figure 4 In the example shown, the observation section 20 extracts three fields of view: 31, 32, and 33. The field of view with the largest area ratio of intermetallic compound 14 among the multiple fields of view 31, 32, and 33 is designated as the first field of view. Furthermore, the ratio Sm / S of intermetallic compound 14 in this first field of view is designated as the area ratio A%. Similarly, the field of view with the smallest area ratio of intermetallic compound 14 among the multiple fields of view 31, 32, and 33 is designated as the second field of view. Furthermore, the ratio Sm / S of intermetallic compound 14 in this second field of view is designated as the area ratio B%. In the sliding member 10 of this embodiment, the difference D between the area ratio A and the area ratio B, i.e., D = AB, is within 20%. That is, the difference D is D ≤ 20%.

[0037] This means that among the multiple fields of view 31, 32, and 33 extracted from the observation section 20, the area ratio of the intermetallic compound 14 contained in the Sn alloy layer 11, i.e., the ratio Sm / S, is not significantly different between the first field of view with the largest proportion of intermetallic compound 14 and the second field of view with the smallest proportion. That is, it indicates that the intermetallic compound 14 is substantially uniformly dispersed throughout the Sn alloy layer 11 without segregation. In this way, the intermetallic compound 14 is dispersed in the Sn alloy layer 11 without segregation, thereby reducing the overall hardness difference of the Sn alloy layer 11. As a result, the fatigue resistance of the sliding member 10 can be improved. Furthermore, the number of fields of view extracted from the observation section 20 is not limited to the three in the example, but can also be two or more.

[0038] In addition to the above, in the sliding member 10 of this embodiment, such as Figure 4 As shown, an observation area 41 is defined within 3% of the thickness of the Sn alloy layer 11, extending from the interface 21 with the inner lining metal layer 12 towards the opposite side of the inner lining metal layer 12. That is, the observation area 41 is defined in the thickness direction of the Sn alloy layer 11 within a range of 3% of the thickness of the Sn alloy layer 11 from the interface 21 towards the sliding surface 15. The field of view 33, one of the aforementioned fields of view 31, 32, and 33, is defined within... Figure 4 In observation region 41, the ratio of the total area Sm of the intermetallic compounds 14 to the total area S of the Sn alloy layer 11, i.e., Sm / S, is 5% or more and 60% or less. That is, the ratio Sm / S of the total area Sm of the intermetallic compounds 14 in observation region 41 to the total area S of the Sn alloy layer 11 in observation region 41 is 5% ≤ Sm / S × 100 ≤ 60%. The total area Sm of the intermetallic compounds 14 is determined by image analysis of an image of observation region 41, as described above. Observation region 41 is the area of ​​the Sn alloy layer 11 near the interface 21 of the inner lining metal layer 12. When considering the bonding force between the Sn alloy layer 11 and the inner lining metal layer 12, segregation of intermetallic compounds 14 is not preferred in the area of ​​the Sn alloy layer 11 near the interface 21. By setting the area ratio Sm / S of the intermetallic compound 14 in the observation region 41 to 5% ≤ Sm / S × 100 ≤ 60%, the ratio of the total contact length Lx between the Sn alloy parent phase 13 and the inner lining metal layer 12 to the total length L of the interface 21, i.e., the contact ratio Lx / L, is increased. Therefore, the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12 can be ensured. In this case, when the ratio Sm / S of the intermetallic compound 14 in the observation region 41 is 5% ≤ Sm / S × 100 ≤ 50%, the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12 is further improved.

[0039] The sliding member 10 in this embodiment is as follows: Figure 5 The diagram also includes an Fe-Sn compound 51. The Fe-Sn compound 51 is a compound derived from Sn contained in the Sn alloy layer 11 and Fe contained in the inner lining metal layer 12. As described above, this Fe-Sn compound 51 does not constitute the intermetallic compound 14 of this embodiment. When the Sn alloy layer 11 is laminated onto the inner lining metal layer 12, the Fe-Sn compound 51 is generated near the interface 21 on the Sn alloy layer 11 side. The Fe-Sn compound 51 is formed upright from the interface 21 towards the Sn alloy layer 11 side, taking the form of a needle-like, columnar, or rod-like shape with a long axis 52. Therefore, the long axis 52 of the Fe-Sn compound 51 extends in a direction substantially perpendicular to the interface 21. The long axis 52 of the Fe-Sn compound 51 is 40 μm or less.

[0040] As described above, the Fe-Sn compound 51 is formed upright from the interface 21 toward the Sn alloy layer 11. Furthermore, the distance Z between the vertices 53 of the Fe-Sn compound 51 on the opposite side of the interface 21 from another adjacent Fe-Sn compound 51 is 0.5 μm or more. This ensures a sufficient distance between the Fe-Sn compound 51 and its adjacent counterpart. The formation of the Fe-Sn compound 51 near the interface 21 affects the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12. That is, the Fe-Sn compound 51 is sparsely formed at the interface 21, thereby increasing the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12. By setting the distance between the vertices 53 of adjacent Fe-Sn compounds 51 to 0.5 μm or more, the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12 can be sufficiently ensured. Furthermore, by reducing the heat applied to the lining metal layer 12, the long axis 52 of the generated Fe-Sn compound becomes less than 40 μm. Therefore, the overall length of the generated Fe-Sn compound is shortened, which can improve the bonding strength between the Sn alloy layer 11 and the lining metal layer 12.

[0041] The Sn alloy layer 11 of the sliding member 10 contains intermetallic compounds 14 comprising square particles 61 with a square cross-section in the observation section 20. Square particles 61 refer to particles with a cuboid shape, such as cubes or cuboids, having sufficient length in each of the three dimensions. In this embodiment, the distance between the centers of the square particles 61 and adjacent square particles 61 in the intermetallic compound 14 contained in the Sn alloy layer 11 is 10 μm or more. The intermetallic compound 14 is uniformly dispersed in the Sn alloy layer 11 as described above, without segregation, which is preferable for improving fatigue resistance. If the distance between the centers of the square particles 61 is 10 μm or more, it indicates that the intermetallic compound 14 is adequately dispersed in the Sn alloy layer 11 without segregation. When sufficient distance is ensured between the centers of the square particles 61, the overall hardness difference of the Sn alloy layer 11 becomes smaller. As a result, the fatigue resistance of the sliding alloy can be improved. Furthermore, the outer diameter of the square particles 61 is preferably set to 30 μm or less. By setting the outer diameter of the square particles 61 to less than 30 μm, the Sn alloy layer 11 can reliably ensure hardness.

[0042] The amount of Sb added in the Sn alloy layer 11 is preferably set to 12% by mass or less. This reduces the segregation of intermetallic compounds 14 in the Sn alloy layer 11 when using a manufacturing method involving rapid heating and rapid cooling. Furthermore, the amount of Cu added in the Sn alloy layer 11 is preferably set to 18% by mass or less. This reduces the segregation of intermetallic compounds 14 in the Sn alloy layer 11 when using a manufacturing method involving rapid heating and rapid cooling. The Bi added in the Sn alloy layer 11 helps to improve the strength of the Sn alloy layer 11. On the other hand, if the amount of Bi added is too large, it will lead to a decrease in adhesion with the inner lining metal layer 12. Therefore, the amount of Bi added in the Sn alloy layer 11 is set to 5% by mass or less, thereby achieving both increased strength and improved adhesion. The amount of Ag and Zn added in the Sn alloy layer 11 is set to 10% by mass or less, thereby reducing the segregation of intermetallic compounds 14 while improving adhesion with the inner lining metal layer 12. Since the Cr and Ba contained in the Sn alloy layer 11 contribute to the miniaturization of the generated intermetallic compound 14, it is preferable to add less than 0.5% by mass.

[0043] Next, the manufacturing method of the sliding member 10 will be described.

[0044] The sliding component 10 is manufactured by laser cladding or centrifugal casting.

[0045] When using laser cladding, the laser cladding device is as follows: Figure 7A laser 72 is applied to a substrate 71, which forms the inner lining metal layer 12. By irradiating the substrate 71 with the laser 72, the substrate 71 melts, forming a molten pool 73. The laser cladding apparatus provides a material 74, which forms the Sn alloy layer 11, to the molten pool 73 formed by the melting of the substrate 71. The material 74 forming the Sn alloy layer 11 is a powder centered on Sn, which forms the Sn alloy matrix phase 13, and incorporating various elements that generate intermetallic compounds 14. In this way, by providing material 74 to the molten pool 73 of the substrate 71 irradiated with the laser 72, the Sn alloy layer 11 is welded to the surface of the substrate 71 in a weld overlay manner. By cooling the welded Sn alloy layer 11, a sliding member 10 with the Sn alloy layer 11 stacked on the inner lining metal layer 12 is manufactured.

[0046] Furthermore, in the case of using centrifugal casting, such as Figure 8 As shown, the substrate 81, which forms the lining metal layer 12, is formed in a cylindrical shape. In this case, the substrate 81 is not limited to a cylindrical shape; it can also be a semi-segmented shape divided in two along the circumferential direction, or a shape divided into three or more arc rings. During centrifugal casting, the material that forms the Sn alloy layer 11 is heated to, for example, 600°C or higher and melted. The molten material flows into the inner circumferential side of the rotating substrate 81. At this time, the substrate 81 is cooled from the outer circumferential side opposite to the side supplying the material. As a result, the flowing material solidifies in a state of being stacked on the inner circumferential side of the substrate 81. The result is a sliding member with the Sn alloy layer 11 stacked on the lining metal layer 12.

[0047] When using laser cladding, the formation of the Sn alloy matrix phase 13 and intermetallic compound 14 contained in the Sn alloy layer 11 is controlled by changing conditions such as the output of the laser 72 and the supply speed of the material 74. Furthermore, when using centrifugal casting, the formation of the Sn alloy matrix phase 13 and intermetallic compound 14 contained in the Sn alloy layer 11 is controlled by changing conditions such as the material temperature, the material supply speed, the rotation speed of the substrate 81, or the cooling rate of the substrate 81.

[0048] Hereinafter, an embodiment of the sliding member 10 of this embodiment will be described.

[0049] (Material Composition)

[0050] The embodiments and comparative examples of the sliding member 10 use, as follows: Figure 9 The materials shown are of the composition. Specifically, the embodiments and comparative examples used... Figure 9 The materials shown are any one of compositions 1 to 4. Compositions 1 to 4 all form Sn-based alloys and must contain Sb and Cu as additive elements. In addition, compositions 1 to 4 also contain one or more of Ag, Zn, Bi, and Cr as additive elements.

[0051] (Laser cladding)

[0052] The manufacturing process of an embodiment using laser cladding will be described. The embodiment of sliding member 10 uses... Figure 10 The laser cladding apparatus under the conditions shown is used to form the Sn alloy layer 11. The substrate 71, which becomes the lining metal layer 12, uses a plate-shaped "S235JR+C EN10277". The weld thickness of the Sn alloy layer 11 formed by laser cladding is set to 3 mm. The substrate 71 with the welded Sn alloy layer 11 is cooled to room temperature. The output of the laser 72 used in the laser cladding apparatus, and the supply speed of the material 74 that becomes the Sn alloy layer 11 are all specified. Figures 11-15 As shown.

[0053] (Centrifugal casting)

[0054] The manufacturing process using an embodiment employing centrifugal casting will be described. The substrate 81, which forms the lining metal layer 12, is formed into a cylindrical shape using the same material as laser cladding. The casting thickness is set to 5 mm, and the wall thickness of the substrate 81 is set to 6 mm. To prevent oxidation, the surface of the substrate 81 is covered with pure Sn and preheated to 300°C to 400°C in molten Sn.

[0055] The material used to form the Sn alloy layer 11 is prepared by mixing Sn, Cu, Sb, and other additives in a pre-defined composition and melting it in the atmosphere. The molten Sn-based alloy is maintained at 500°C to 600°C in the atmosphere and supplied to a preheated substrate 81. After the molten liquid is supplied, the substrate 81 is cooled from the back side with water. In the case of rapid cooling, the cooling condition is to set the water flow rate to 2400 liters / minute to 2800 liters / minute for 13 seconds. On the other hand, in the case of normal cooling, the cooling condition is to set the water flow rate to 1200 liters / minute to 1600 liters / minute for 20 seconds.

[0056] (Evaluation of the Implementation Examples)

[0057] Examples and comparisons of the formed sliding member 10 Figures 11-15 As shown, fatigue resistance was evaluated by the hardness of the Sn alloy layer 11, and the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12 was evaluated by the Chalmers test. In the fatigue resistance evaluation, a Vickers hardness of 38 HV or higher for the formed Sn alloy layer 11 was considered acceptable ("○"), and less than 38 HV was considered unacceptable ("×"). Furthermore, in the bonding strength evaluation, a Chalmers test result of 75 MPa or higher was considered acceptable ("○"), and less than 75 MPa was considered unacceptable ("×"). Figures 11-15In the manufacturing methods shown, "laser" means forming a Sn alloy layer by laser cladding, "casting (rapid cooling)" means casting accompanied by rapid cooling, and "casting" means ordinary casting without rapid cooling.

[0058] also, Figures 11-15 In the "Sm / S" column, as shown in the example Figure 4 In the observation section 20 shown, the fields of view are designated as "field of view 1", "field of view 2", and "field of view 3" from the position furthest from the inner lining metal layer 12. Field of view 3 is contained within the observation area 41 closest to the inner lining metal layer 12. Furthermore, among these fields of view 1, 2, and 3, the field of view with the largest ratio Sm / S of the intermetallic compound 14 corresponds to the first field of view, and the field of view with the smallest ratio Sm / S of the intermetallic compound 14 corresponds to the second field of view. The difference D is calculated based on the area ratio A of the first field of view and the area ratio B of the second field of view. The average of the area ratios calculated using these fields of view 1, 2, and 3 is then used as the ratio Sm / S of the total area Sm of the intermetallic compound 14 in the observation section 20 relative to the total area S of the Sn alloy layer 11.

[0059] According to these Figure 11 , Figures 13-15 In the embodiments shown, in Examples 1 to 17 where the difference D of the Sn alloy layer 11 and the contact ratio Lx / L are satisfied, the hardness and Chalmers test results are all acceptable ("○"). In contrast, Figure 12 Comparative Examples 1, 3, 4, and 6 all meet the difference D, but do not meet the contact ratio Lx / L. The contact ratio Lx / L affects the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12. It can be seen that the bonding strength of Comparative Examples 1 to 4 and Comparative Example 6, with a contact ratio Lx / L of less than 30%, is lower than that of the respective embodiments. In addition, Comparative Example 2 does not meet the difference D, and the Chalmers test result is unqualified "×". This is because in the case of Comparative Example 2, which does not meet the difference D, the intermetallic compound 14 segregates. Although Comparative Example 5 meets the difference D and Lx / L, its hardness is unqualified "×". This is because in the case of Comparative Example 5, which is manufactured by casting, the micronization of the intermetallic compound 14 in the Sn alloy layer 11 is insufficient, and the strength of the Sn alloy layer 11 is reduced.

[0060] according to Figure 13As shown in Examples 7 to 10, the Sm / S ratio in the field of view 3 encompassed by the observation area 41 on the Sn alloy layer 11 is preferably 5% or more and 60% or less, which helps to improve the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12. That is, compared with Example 7, the Chalmers test results are improved in Example 8 (50% Sm / S ratio), Example 9 (19% Sm / S ratio), and Example 10 (60% Sm / S ratio).

[0061] according to Figure 14 As shown in Examples 11 to 13, the length of the major axis 52 of the Fe-Sn compound 51 contained in the Sn alloy layer 11 and the distance between its vertices 53 are preferably 40 μm or less and 0.5 μm or more, respectively, which helps to improve the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12. That is, the Chalmers test results of Examples 11 and 12, which satisfy the requirements of the length of the major axis 52 of the Fe-Sn compound 51 and the distance between its vertices 53, are improved compared to Example 13, which does not satisfy these requirements.

[0062] according to Figure 15 As shown in Examples 14 to 17, the center-to-center distance of the square particles 61 contained in the Sn alloy layer 11 is preferably 10 μm or more, which helps to improve the hardness of the Sn alloy layer 11. That is, the hardness of the Sn alloy layer 11 in Examples 14, 16, and 17, where the center-to-center distance of the square particles 61 is 10 μm or more, is improved.

[0063] As explained above, the sliding member 10 of this embodiment, by specifically defining the contact state between the Sn alloy matrix phase 13 and the inner lining metal layer 12, and the dispersion state of the intermetallic compound 14 contained in the Sn alloy layer 11, ensures the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12 without compromising the fatigue resistance of the Sn alloy layer 11. Furthermore, in this embodiment, it is not necessary to add environmentally harmful substances such as Cd and Be. Therefore, fatigue resistance and the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12 can be improved while eliminating substances with high environmental impact.

[0064] The present invention described above is not limited to the above embodiments, and can be applied to various embodiments without departing from its spirit.

[0065] For example, the sliding member 10 may also have an intermediate layer between the Sn alloy layer 11 and the inner lining metal layer 12. In this case, the intermediate layer is preferably Sn or a Sn alloy plating, etc. By providing such an intermediate layer between the Sn alloy layer 11 and the inner lining metal layer 12, the bonding strength between the Sn alloy layer 11 and the inner lining metal layer 12 can be further improved.

Claims

1. A sliding member having a Sn alloy layer and an Fe-based inner lining metal layer, The Sn alloy layer comprises a Sn alloy matrix phase and Sn-based intermetallic compounds dispersed in the Sn alloy matrix phase. The Fe-based lining metal layer has the Sn alloy layer disposed on at least one end face side. The Sn alloy layer comprises 3.0–12% by mass of Sb, 4.0–18% by mass of Cu, and the remainder being Sn containing unavoidable impurities. The Vickers hardness of the Sn alloy layer is above 38HV. In any observation section at the interface between the Sn alloy layer and the inner lining metal layer, the total length of the Sn alloy matrix phase contained in the Sn alloy layer in contact with the inner lining metal layer is more than 30% of the total length of the interface. In the observed cross section, the total area of ​​the intermetallic compounds is more than 40% and less than 70% of the total area of ​​the Sn alloy layer. When multiple fields of view of the same area are arbitrarily extracted from the cross section of the Sn alloy layer, the difference D=AB between the area ratio A% of the first field of view with the largest area ratio of the intermetallic compound and the area ratio B% of the second field of view with the smallest area ratio of the intermetallic compound is within 20%.

2. The sliding member according to claim 1, wherein, When the observation area is set to within 3% of the Sn alloy layer along the thickness direction from the interface to the opposite side of the inner lining metal layer, The total area of ​​the intermetallic compounds in the observation area is more than 5% and less than 60% of the total area of ​​the Sn alloy layer in the observation area.

3. The sliding member according to claim 1, wherein, The sliding member further comprises an Fe-Sn compound, which is a compound composed of Sn from the Sn alloy layer and Fe from the lining metal layer. The Fe-Sn compound does not constitute the intermetallic compound. The Fe-Sn compound stands upright from the interface toward the Sn alloy layer and is formed as a needle-like structure with a short axis and a long axis less than 40 μm. The distance between the Fe-Sn compound and another adjacent Fe-Sn compound at the vertex on the opposite side of the interface is greater than 0.5 μm.

4. The sliding member according to claim 1, wherein, The intermetallic compound comprises square particles with a square cross-section. The center-to-center distance between the square particle and other adjacent square particles is more than 10 μm.

5. A method for manufacturing a sliding member, wherein the sliding member is any one of claims 1 to 4, the manufacturing method comprising the following steps: In the irradiation process, a laser is irradiated onto one end face of the inner lining metal layer; In the input process, the focus of the laser irradiated in the irradiation process is used to input the alloy material that forms the Sn alloy layer; and In the alloy layer formation process, the alloy material introduced in the input process is melted on the surface of the inner lining metal layer by the irradiated laser, the alloy material formed by the melting is bonded to the inner lining metal layer, and the Sn alloy layer is deposited on the inner lining metal layer.

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