Slide member and producing method thereof

Abstract

To provide a slide member high in adhesion force between a Sn alloy layer and a backing layer, and fatigue resistance, while excluding a substance of large environmental load and a producing method thereof.SOLUTION: A slide member 10 of the present embodiment includes a Sn alloy layer 11 and an Fe-based back metal layer 12. In an optional observation cross section 20 at an interface 21 between the Sn alloy layer 11 and the back metal layer 12, a total length of contact between the Sn alloy parent phase 13 contained in the Sn alloy layer 11 and the back metal layer 12 is 30% or more relative to a total length of the interface 21. In the observation cross section 20, a sum of the areas of the intermetallic compound 14 relative to a total area of the Sn alloy layer 11 is 40% or more and 70% or less. When a plurality of fields of view having the same area are arbitrarily extracted from a cross section of the Sn alloy layer 11, the difference D=A-B between the area percentage A% of the first field of view in which the area percentage of the intermetallic compound 14 is maximum and the area percentage B% of a second field of view in which the area percentage of the intermetallic compound 14 is minimum is within 20%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present embodiment relates to a slide member and a manufacturing method thereof. [Background technology]

[0002] The sliding member has, for example, an Sn-based Sn alloy layer on the surface of an Fe-based back metal layer. In order to improve fatigue resistance, the Sn alloy that slides against the counter member is doped with elements such as Cu and Sb that form intermetallic compounds with the Sn that is the parent phase of the Sn alloy layer. On the other hand, excessive addition of Cu or Sb creates brittle Cu deposits near the interface with the back metal layer. 5 This leads to segregation of Sn and the like. Therefore, excessive addition of Cu or Sb leads to a decrease in the adhesive strength between the back 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 mass%. As a result, in Patent Document 1, the Cu, which is an intermetallic compound, 5 Sn 6 and SbSn are refined, and Cu 5 Sn 6 As a result, Patent Document 1 aims to improve the fatigue resistance of the sliding member and the adhesion between the back metal layer and the Sn alloy layer.

[0003] However, in Patent Document 1, in order to reduce segregation while refining the intermetallic compounds in the Sn alloy layer, it is necessary to add Cd and Be. Considering the impact on the environment, it is desirable to refrain from using these elements Cd and Be. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 50-1687 Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore an object of the present invention to provide a sliding member that has high adhesion between the Sn alloy layer and the back metal layer and high fatigue resistance while eliminating substances that have a large environmental impact, and a method for manufacturing the same. [Means for solving the problem]

[0006] In order to solve the above problems, the slide member of the present embodiment includes an Sn alloy layer including an Sn alloy parent phase and an Sn-based intermetallic compound dispersed in the Sn alloy parent phase, and an Fe-based back metal layer having the Sn alloy layer provided on at least one end face thereof. In any observed cross-section at the interface between the Sn alloy layer and the back metal layer, the total length of contact between the Sn alloy parent phase contained in the Sn alloy layer and the back metal layer with respect to the total length of the interface is 30% or more, the sum of the areas of the intermetallic compounds with respect to the total area of ​​the Sn alloy layer in the observed cross-section is 40% or more and 70% or less, and when multiple fields of view having 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 a first field of view in which the area ratio of the intermetallic compounds is maximum and the area ratio B% of a second field of view in which the area ratio of the intermetallic compounds is minimum among the multiple fields of view is within 20%.

[0007] The inventors have found that the contact state between the Sn alloy matrix of the Sn alloy layer and the back metal layer at the interface between the Sn alloy layer and the back metal layer, and the dispersion state of the intermetallic compounds contained in the Sn alloy layer affect the adhesive strength between the Sn alloy layer and the back metal layer. In this embodiment, by specifying the contact state between the Sn alloy matrix and the back metal layer and the dispersion state of the intermetallic compounds as described above, the adhesive strength between the Sn alloy layer and the back metal layer is ensured without impairing the fatigue resistance of the Sn alloy layer. In addition, in this embodiment, it is not necessary to add substances that have an impact on the environment, such as Cd and Be. Therefore, it is possible to increase the adhesive strength and fatigue resistance between the Sn alloy layer and the back metal layer while eliminating substances that have a large environmental load.

[0008] The manufacturing method of the slide member of this embodiment includes an irradiation step, a throwing step, and an alloy layer forming step. In the irradiation step, a laser beam is irradiated onto one end face of the back metal layer. In the throwing step, an alloy material for forming a Sn alloy layer is thrown into the focus of the laser beam irradiated in the irradiation step. In the alloy layer forming step, the alloy material thrown in the throwing step is melted on the surface of the back metal layer by the irradiated laser beam, and the alloy material formed by the melting is joined to the back metal layer, thereby depositing the Sn alloy layer on the back metal layer.

[0009] In this embodiment, the Sn alloy layer is built up on the surface of the back metal layer by so-called laser cladding. This controls the generation of intermetallic compounds that disperse in the Sn alloy matrix at the interface between the Sn alloy layer and the back metal layer. Therefore, it is possible to increase the adhesion between the Sn alloy layer and the back metal layer and the fatigue resistance while eliminating substances that have a large environmental impact. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a sliding member according to an embodiment; [Diagram 2] FIG. 2 is a schematic diagram showing the structure of a Sn alloy layer of a slide member according to one embodiment; [Diagram 3] FIG. 1 is a schematic cross-sectional view showing an observed cross section of a sliding member according to an embodiment; [Figure 4] FIG. 1 is a schematic cross-sectional view showing an observed cross section of a sliding member according to an embodiment; [Diagram 5] FIG. 1 is a schematic cross-sectional view showing an observed cross section of a sliding member according to an embodiment; [Figure 6] FIG. 2 is a schematic cross-sectional view showing a Sn alloy layer of a slide member according to one embodiment. [Figure 7] FIG. 1 is a schematic diagram for explaining the manufacture of a sliding member according to an embodiment using laser cladding; [Figure 8] FIG. 1 is a schematic diagram for explaining the manufacture of a slide member according to an embodiment using centrifugal casting; [Figure 9] FIG. 1 is a schematic diagram showing the composition of a material used in a sliding member according to an embodiment. [Figure 10]FIG. 1 is a schematic diagram showing the conditions of laser cladding used in the manufacture of a sliding member according to an embodiment. [Figure 11] FIG. 13 is a schematic diagram showing test results of an example of a sliding member according to an embodiment. [Figure 12] FIG. 1 is a schematic diagram showing test results of a comparative example of a sliding member. [Figure 13] FIG. 13 is a schematic diagram showing test results of an example of a sliding member according to an embodiment. [Figure 14] FIG. 13 is a schematic diagram showing test results of an example of a sliding member according to an embodiment. [Figure 15] FIG. 13 is a schematic diagram showing test results of an example of a sliding member according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the sliding member will be described with reference to the drawings. As shown in FIG. 1, the sliding member 10 includes a Sn alloy layer 11 and a back metal layer 12. The Sn alloy layer 11 is formed of a Sn-based alloy, and includes a Sn alloy parent phase 13 and an intermetallic compound 14 as shown in FIG. 2. The Sn alloy parent phase 13 is a parent phase formed of a Sn alloy constituting the Sn alloy layer 11. The intermetallic compound 14 is formed in the form of particles as a compound of various elements constituting the Sn alloy layer 11, and is dispersed in the Sn alloy parent phase 13. The back metal layer 12 is formed of an Fe-based alloy mainly containing Fe, such as steel or carbon steel. The Sn alloy layer 11 forms a sliding surface 15 on the side opposite to the back metal layer 12, which slides against a counter member (not shown). The sliding member 10 may have another layer, such as an overlay layer, on the end face, i.e., the surface, of the Sn alloy layer 11 opposite to the back metal layer 12. For example, the slide member 10 may have an intermediate layer and an overlay layer (not shown) on the sliding surface 15 side of the Sn alloy layer 11. The Sn alloy layer 11 has a Vickers hardness of 38 HV or more. In this way, by increasing the hardness of the Sn alloy layer 11, the slide member 10 can have improved fatigue resistance.

[0012] The Sn alloy layer 11 is formed of Sn containing 3.0 to 12 mass% Sb and 4.0 to 18 mass% Cu, with the remainder being unavoidable impurities. 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 may contain up to 5.0 mass% Bi, up to 10 mass% Ag, up to 10 mass% Zn, up to 0.5 mass% Cr, and up to 0.5 mass% Ba. As a result, 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 parent phase 13. The intermetallic compounds 14 are not limited to compounds of two elements as exemplified above, and may be compounds of three or more elements. Note that, for example, Fe--Sn compounds derived from Sn contained in the Sn alloy layer 11 and Fe contained in the back metal layer 12 are not included in the intermetallic compounds in this embodiment.

[0013] An arbitrary observation cross section 20 is set for this sliding member 10 as shown in FIG. 1 and FIG. 3. The observation cross section 20 is set in an arbitrary range of, for example, several μm×several μm to several mm×several mm in a cross section cut in the thickness direction of the sliding member 10. In this observation cross section 20, the thickness direction is the Y direction, and the direction perpendicular to the thickness is the X direction. In the observation cross section 20, the interface 21 between the Sn alloy layer 11 and the back metal layer 12 extends in the X direction. The total length of this observation cross section 20 in the X direction, that is, the distance between X1 and X2, is equal to the total length L of the interface 21 between the Sn alloy layer 11 and the back metal layer 12. On the other hand, the Sn alloy layer 11 contains an intermetallic compound 14. Therefore, between the Sn alloy layer 11 and the back metal layer 12, there are a portion where the Sn alloy parent phase 13 of the Sn alloy layer 11 and the back metal layer 12 contact and a portion where the intermetallic compound 14 and the back metal layer 12 contact. In the X direction, the length of the portion where the Sn alloy matrix 13 and the back metal layer 12 contact each other is defined as Lxn, where n is a natural number. In this case, the total length Lx of the portion where the Sn alloy matrix 13 and the back metal layer 12 contact each other is Lx=Lx1+Lx2+Lx3+···+Lxn. The length Lxn of the portion where the Sn alloy matrix 13 and the back metal layer 12 contact each other is measured by image analysis of an image taken of the observation cross section 20. For simplicity of explanation, the following explanation will be given taking n=4 as shown in FIG. 3 as an example.

[0014] In the example shown in FIG. 3, the total length Lx of the contact portion between the Sn alloy parent phase 13 and the back metal layer 12 is Lx=Lx1+Lx2+Lx3+Lx4. In this embodiment, the total length Lx of the contact portion between the Sn alloy parent phase 13 and the back metal layer 12 with respect to the total length L of the interface 21 is 30% or more. That is, the contact ratio Lx / L is Lx / L×100≧30(%). Thus, in this embodiment, in the slide member 10, the contact portion between the Sn alloy parent phase 13 and the back metal layer 12 at the interface 21 between the Sn alloy layer 11 and the back metal layer 12 is 30% or more of the total length L of the interface 21. The adhesive strength between the Sn alloy layer 11 and the back metal layer 12 is ensured at the contact portion between the Sn alloy parent phase 13 and the back metal layer 12. In the case of the slide member of this embodiment, the Sn alloy parent phase 13 and the back metal layer 12 are in contact with each other at the interface 21 over an area that is 30% or more of the total length L. This ensures a sufficient total length between the Sn alloy layer 11 and the back metal layer 12 to ensure adhesive strength.

[0015] In the slide member 10 of this embodiment, the sum of the areas of the intermetallic compounds 14 relative to the total area of ​​the Sn alloy layer 11 in any observation cross section 20 is 40% or more and 70% or less. That is, the ratio Sm / S, which is the sum of the areas Sm of the intermetallic compounds 14 contained in the observation cross section 20 relative to the total area S of the Sn alloy layer 11 in the observation cross section 20, is 40%≦Sm / S×100≦70%. The sum of the areas Sm of the intermetallic compounds 14 is measured by image analysis of an image taken of the observation cross section 20, similarly to the length Lxn. The intermetallic compounds 14 contribute more to improving the fatigue resistance of the slide member 10 as the ratio Sm / S, which is the ratio of the area in the Sn alloy layer 11, increases. On the other hand, if 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 back metal layer 12 decreases, and the adhesive strength between the Sn alloy layer 11 and the back metal layer 12 decreases. By setting the ratio Sm / S to be in the range of 40%≦Sm / S×100≦70%, the slide member 10 can achieve both improved fatigue resistance and improved adhesive strength between the Sn alloy layer 11 and the back metal layer 12.

[0016] Furthermore, in the sliding member 10 of this embodiment, a plurality of visual fields having the same area are arbitrarily extracted from the observation cross section 20 as shown in FIG. 4. In the example shown in FIG. 4, three visual fields 31, 32, and 33 are extracted from the observation cross section 20. At this time, the visual field in which the area ratio of the included intermetallic compound 14 is maximum among the plurality of visual fields 31, 32, and 33 is set as the first visual field. The ratio Sm / S of the intermetallic compound 14 in this first visual field is set as the area ratio A%. Similarly, the visual field in which the area ratio of the included intermetallic compound 14 is minimum among the plurality of visual fields 31, 32, and 33 is set as the second visual field. The ratio Sm / S of the intermetallic compound 14 in this second visual field is set 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, D=AB, is within 20%. That is, the difference D is D≦20%.

[0017] This indicates that, among the multiple visual fields 31, 32, and 33 extracted from the observation cross section 20, the area ratio of the intermetallic compounds 14 contained in the Sn alloy layer 11, that is, the ratio Sm / S, is not significantly different between the first visual field in which the ratio of the intermetallic compounds 14 is maximum and the second visual field in which the ratio is minimum. In other words, it indicates that the intermetallic compounds 14 are almost uniformly dispersed throughout the Sn alloy layer 11 and are not segregated. In this way, the intermetallic compounds 14 are dispersed in the Sn alloy layer 11 without segregation, so that the difference in hardness of the Sn alloy layer 11 as a whole is small. As a result, the fatigue resistance of the sliding member 10 can be improved. The number of visual fields extracted from the observation cross section 20 is not limited to three as illustrated, and may be two or four or more.

[0018] In addition to the above, in the sliding member 10 of the present embodiment, as shown in FIG. 4, an observation region 41 is set in the Sn alloy layer 11 in a region within 3% of the interface 21 with the back metal layer 12 toward the opposite side of the back metal layer 12 in the thickness direction. That is, the observation region 41 is set in a range of 3% of the thickness of the Sn alloy layer 11 from the interface 21 toward the sliding surface 15 side in the thickness direction of the Sn alloy layer 11. Of the above-mentioned visual fields 31, 32, and 33, the visual field 33 is set in the observation region 41 in FIG. 4. In this observation region 41, the ratio Sm / S, which is the sum Sm of the areas of the intermetallic compounds 14 to the total area S of the Sn alloy layer 11, is 5% or more and 60% or less. That is, the ratio Sm / S of the sum Sm of the areas of the intermetallic compounds 14 in the observation region 41 to the total area S of the Sn alloy layer 11 in the observation region 41 is 5%≦Sm / S×100≦60%. The sum of the areas of the intermetallic compounds 14, Sm, is measured by image analysis of an image of the observation region 41, as described above. The observation region 41 is a region of the Sn alloy layer 11 near the interface 21 close to the back metal layer 12. Considering the adhesive strength between the Sn alloy layer 11 and the back metal layer 12, segregation of the intermetallic compounds 14 is not preferable in the region of the Sn alloy layer 11 near the interface 21. By setting the ratio Sm / S of the areas of the intermetallic compounds 14 in the observation region 41 to 5%≦Sm / S×100≦60%, the ratio of the sum of the lengths Lx of the contact between the Sn alloy parent phase 13 and the back metal layer 12 to the total length L of the interface 21, that is, the contact ratio Lx / L, increases. Therefore, the adhesive strength between the Sn alloy layer 11 and the back 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 adhesive strength between the Sn alloy layer 11 and the back metal layer 12 is further improved.

[0019] The sliding member 10 of this embodiment further contains an Fe-Sn compound 51 as shown in FIG. 5. The Fe-Sn compound 51 is a compound derived from Sn contained in the Sn alloy layer 11 and Fe contained in the back metal layer 12. As described above, the Fe-Sn compound 51 does not constitute the intermetallic compound 14 of this embodiment. When the Sn alloy layer 11 is laminated on the back metal layer 12, the Fe-Sn compound 51 is generated from the vicinity of the interface 21 toward the Sn alloy layer 11. The Fe-Sn compound 51 is generated in a needle-like, columnar or rod-like shape having a long axis 52, rising from the interface 21 toward the Sn alloy layer 11. 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.

[0020] As described above, the Fe-Sn compounds 51 are formed rising from the interface 21 toward the Sn alloy layer 11. The distance Z between the apexes 53 of the ends of the Fe-Sn compounds 51 on the opposite side to the interface 21 is 0.5 μm or more between the adjacent Fe-Sn compounds 51. In this way, a sufficient distance is ensured between the Fe-Sn compounds 51 and the adjacent Fe-Sn compounds 51. The Fe-Sn compounds 51 are formed near the interface 21 and affect the adhesive strength between the Sn alloy layer 11 and the back metal layer 12. That is, the adhesive strength between the Sn alloy layer 11 and the back metal layer 12 is improved by the Fe-Sn compounds 51 being sparsely formed at the interface 21. The adhesive strength between the Sn alloy layer 11 and the back metal layer 12 is sufficiently ensured by setting the distance between the apexes 53 of the adjacent Fe-Sn compounds 51 to 0.5 μm or more. In addition, the Fe-Sn compound produced has a long axis 52 of 40 μm or less by reducing the heat applied to the back metal layer 12. Therefore, the total length of the produced Fe-Sn compound is shortened, and the adhesive strength between the Sn alloy layer 11 and the back metal layer 12 can be improved.

[0021] The intermetallic compound 14 contained in the Sn alloy layer 11 of the sliding member 10 includes rectangular particles 61 having a rectangular cross section in the observation cross section 20. The rectangular particles 61 are particles having a rectangular shape having a sufficient overall length in each axis direction in three dimensions, such as a cube or a rectangular parallelepiped. In this embodiment, the rectangular particles 61 among the intermetallic compounds 14 contained in the Sn alloy layer 11 have a center-to-center distance of 10 μm or more between adjacent rectangular particles 61. As described above, it is preferable for the intermetallic compound 14 to be uniformly dispersed in the Sn alloy layer 11 and not segregated, in order to improve fatigue resistance. If the center-to-center distance of the rectangular particles 61 is 10 μm or more, it indicates that the intermetallic compound 14 is appropriately dispersed in the Sn alloy layer 11 and not segregated. When a sufficient distance is secured between the centers of the rectangular particles 61 in this way, the Sn alloy layer 11 has a small difference in hardness as a whole. As a result, the fatigue resistance of the sliding alloy can be improved. Moreover, it is preferable that the rectangular particles 61 have an outer diameter of 30 μm or less. By setting the outer diameter of the rectangular particles 61 to 30 μm or less in this manner, the Sn alloy layer 11 can reliably ensure its hardness.

[0022] The amount of Sb added to the Sn alloy layer 11 is preferably 12 mass% or less. This can reduce the segregation of the intermetallic compound 14 in the Sn alloy layer 11 when a manufacturing method that involves rapid heating and rapid cooling is used. The amount of Cu added to the Sn alloy layer 11 is preferably 18 mass% or less. This can reduce the segregation of the intermetallic compound 14 in the Sn alloy layer 11 when a manufacturing method that involves rapid heating and rapid cooling is used. Bi added to the Sn alloy layer 11 contributes to improving the strength of the Sn alloy layer 11. On the other hand, if the amount of Bi added is excessive, it will cause a decrease in adhesion to the back metal layer 12. Therefore, by setting the amount of Bi added to the Sn alloy layer 11 to 5 mass% or less, it is possible to improve the strength and adhesion. By setting the amount of Ag and Zn added to the Sn alloy layer 11 to 10 mass% or less, it is possible to reduce the segregation of the intermetallic compound 14 and improve the adhesion to the back metal layer 12. The Cr and Ba contained in the Sn alloy layer 11 contribute to making the intermetallic compounds 14 that are generated finer, and therefore it is preferable to add them in an amount of 0.5 mass % or less.

[0023] Next, a method for manufacturing the slide member 10 will be described. The slide member 10 is manufactured by laser cladding or centrifugal casting. When laser clad is used, the laser clad device irradiates a laser beam 72 onto a substrate 71 that will become the back metal layer 12, as shown in FIG. 7. By irradiating the substrate 71 with the laser beam 72, the substrate 71 melts to form a molten pool 73. The laser clad device provides a material 74 that will become the Sn alloy layer 11 to the molten pool 73 that is generated by melting the substrate 71. The material 74 that will become the Sn alloy layer 11 is a powder containing Sn that will become the Sn alloy parent phase 13 as a main component and various elements that will generate the intermetallic compound 14 added thereto. In this way, by providing the material 74 to the molten pool 73 of the substrate 71 irradiated with the laser beam 72, the Sn alloy layer 11 is welded in an overlay form to the surface of the substrate 71. By cooling the welded Sn alloy layer 11, a slide member 10 in which the Sn alloy layer 11 is laminated on the back metal layer 12 is manufactured.

[0024] In addition, when centrifugal casting is used, the substrate 81 that will become the back metal layer 12 is formed into a cylindrical shape as shown in FIG. 8. In this case, the substrate 81 is not limited to a cylindrical shape, and may be a half-split shape divided into two in the circumferential direction, or an arc-shaped ring shape divided into three or more parts. When centrifugal casting is performed, the material that will become the Sn alloy layer 11 is heated to, for example, 600° C. or higher and melted. The molten material is poured into the inner periphery of the rotating substrate 81. At this time, the substrate 81 is cooled from the outer periphery opposite to the side to which the material is supplied. As a result, the poured material hardens while being laminated on the inner periphery of the substrate 81. As a result, a sliding member in which the Sn alloy layer 11 is laminated on the back metal layer 12 is manufactured.

[0025] When laser cladding is used, the generation of the Sn alloy parent phase 13 and the intermetallic compound 14 contained in the Sn alloy layer 11 is controlled by changing conditions such as the output of the laser light 72 and the supply speed of the material 74. When centrifugal casting is used, the generation of the Sn alloy parent phase 13 and the intermetallic compound 14 contained in the Sn alloy layer 11 is controlled by changing conditions such as the temperature of the material, the supply speed of the material, the rotation speed of the base material 81, or the cooling speed of the base material 81.

[0026] Examples of the sliding member 10 of this embodiment will be described below. (Material composition) In the examples and comparative examples of the slide member 10, materials having compositions as shown in Fig. 9 were used. Specifically, in the examples and comparative examples, materials having any of compositions 1 to 4 shown in Fig. 9 were used. All of compositions 1 to 4 form Sn-based alloys and essentially contain Sb and Cu as additive elements. Furthermore, compositions 1 to 4 contain at least one of Ag, Zn, Bi, and Cr as additive elements.

[0027] (Laser clad) The manufacture of an embodiment using laser cladding will be described. In the embodiment of the sliding member 10, the Sn alloy layer 11 was formed using a laser cladding device under the conditions shown in FIG. 10. The base material 71 that becomes the back metal layer 12 was made of plate-shaped "S235JR+C EN10277". The Sn alloy layer 11 formed by laser cladding had a build-up thickness of 3 mm. The base material 71 to which the Sn alloy layer 11 was welded was cooled at room temperature. The conditions such as the output of the laser light 72 used in the laser cladding device, and the supply speed of the material 74 that becomes the Sn alloy layer 11 are shown in FIG. 11 to FIG. 15.

[0028] (Centrifugal casting) The manufacturing of the embodiment using centrifugal casting will be described. The base material 81 which becomes the back metal layer 12 was formed into a cylindrical shape using the same material as the laser clad. The casting thickness was set to 5 mm, and the thickness of the base material 81 was set to 6 mm. The surface of the base material 81 was covered with pure Sn to prevent oxidation, and it was preheated to 300°C to 400°C in molten Sn.

[0029] The material to be the Sn alloy layer 11 was prepared by mixing Sn, Cu, Sb and other additive elements in a preset composition and melting it in the air. The molten Sn-based alloy was kept at 500°C to 600°C in the air and supplied to the preheated substrate 81. After the molten metal was supplied to the substrate 81, it was cooled with water from the back side. When performing rapid cooling, the cooling conditions were a water flow rate of 2400 L / min to 2800 L / min for 13 seconds. On the other hand, when performing normal cooling, the cooling conditions were a water flow rate of 1200 L / min to 1600 L / min for 20 seconds.

[0030] (Evaluation of Examples) As shown in Figs. 11 to 15, the fatigue resistance of the formed sliding member 10 in the examples and comparative examples was evaluated by the hardness of the Sn alloy layer 11, and the adhesive strength between the Sn alloy layer 11 and the back metal layer 12 was evaluated by a Chalmers test. In the evaluation of the fatigue resistance, a Vickers hardness of the formed Sn alloy layer 11 of 38HV or more was evaluated as a pass mark "○", and a Vickers hardness of less than 38HV was evaluated as a fail mark "×". In addition, in the evaluation of the adhesive strength, a result of the Chalmers test of 75MPa or more was evaluated as a pass mark "○", and a result of less than 75MPa was evaluated as a fail mark "×". In the manufacturing methods shown in Figs. 11 to 15, "laser" indicates the formation of the Sn alloy layer by laser cladding, "casting (rapid cooling)" indicates casting accompanied by rapid cooling, and "casting" indicates normal casting without rapid cooling.

[0031] 11 to 15, the columns of "Sm / S" are "viewpoint 1", "viewpoint 2" and "viewpoint 3" in the order from the farthest position from the back metal layer 12 in the observation cross section 20 as shown in FIG. 4. Among these, "viewpoint 3" is included in the observation region 41 closest to the back metal layer 12. Among these "viewpoint 1", "viewpoint 2" and "viewpoint 3", the viewpoint in which the ratio Sm / S of the intermetallic compound 14 is maximum corresponds to the first viewpoint, and the viewpoint in which the ratio Sm / S of the intermetallic compound 14 is minimum corresponds to the second viewpoint. The difference D is calculated from the area ratio A of the first viewpoint and the area ratio B of the second viewpoint. Furthermore, the average value of the area ratios calculated in these "viewpoint 1", "viewpoint 2" and "viewpoint 3" is the ratio Sm / S of the sum Sm of the area of ​​the intermetallic compound 14 to the total area S of the Sn alloy layer 11 in the observation cross section 20.

[0032] According to the examples shown in FIG. 11 and FIG. 13 to FIG. 15, in the examples 1 to 17 that satisfy the difference D and the contact ratio Lx / L in the Sn alloy layer 11, the results of the hardness and the Chalmers test are all pass "○". In contrast, in the comparative examples 1, 3, 4, and 6 shown in FIG. 12, all of them satisfy the difference D, but do not satisfy the contact ratio Lx / L. The contact ratio Lx / L affects the adhesive strength between the Sn alloy layer 11 and the back metal layer 12. It can be seen that the adhesive strength is reduced in the comparative examples 1 to 4 and 6 in which the contact ratio Lx / L is less than 30% compared to the examples. In addition, the comparative example 2 does not satisfy the difference D, and the Chalmers test is fail "×". This is because the intermetallic compound 14 segregates in the case of the comparative example 2 that does not satisfy the difference D. Although the comparative example 5 satisfies the difference D and Lx / L, the hardness is fail "×". This is because, in the case of Comparative Example 5 produced by casting, the intermetallic compounds 14 in the Sn alloy layer 11 are not sufficiently refined, and the strength of the Sn alloy layer 11 is reduced.

[0033] 13, it is found that the ratio Sm / S in the field of view 3 included in the observation area 41 set in the Sn alloy layer 11 is preferably 5% or more and 60% or less, which contributes to improving the adhesive strength between the Sn alloy layer 11 and the back metal layer 12. That is, compared to Example 7, Example 8 with the Sm / S ratio of "50%", Example 9 with the Sm / S ratio of "19%", and Example 10 with the Sm / S ratio of "60%" have improved results in the Chalmers test.

[0034] 14, it is found that the length of the major axis 52 and the distance between the vertices 53 of the Fe-Sn compound 51 contained in the Sn alloy layer 11 are preferably 40 μm or less and 0.5 μm or more, respectively, which contributes to improving the adhesive strength between the Sn alloy layer 11 and the back metal layer 12. That is, Examples 11 and 12, which satisfy the length of the major axis 52 and the distance between the vertices 53 of the Fe-Sn compound 51, show improved results in the Chalmers test compared to Example 13, which does not satisfy these requirements.

[0035] 15, it can be seen that the center-to-center distance of the rectangular particles 61 contained in the Sn alloy layer 11 is preferably 10 μm or more, which contributes to improving the hardness of the Sn alloy layer 11. That is, in Examples 14, 16, and 17 in which the center-to-center distance of the rectangular particles 61 is 10 μm or more, the hardness of the Sn alloy layer 11 is improved.

[0036] As described above, in the slide member 10 of this embodiment, the contact state between the Sn alloy parent phase 13 and the back metal layer 12 and the dispersion state of the intermetallic compound 14 contained in the Sn alloy layer 11 are specified, so that the adhesive strength between the Sn alloy layer 11 and the back metal layer 12 is ensured without impairing the fatigue resistance of the Sn alloy layer 11. Moreover, in this embodiment, it is not necessary to add substances that have an impact on the environment, such as Cd and Be. Therefore, it is possible to increase the adhesive strength and fatigue resistance between the Sn alloy layer 11 and the back metal layer 12 while eliminating substances that have a large environmental load.

[0037] The present invention described above is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist of the invention. For example, the slide member 10 may have an intermediate layer between the Sn alloy layer 11 and the back metal layer 12. In this case, the intermediate layer is preferably a Sn or Sn alloy plating layer, etc. By providing such an intermediate layer between the Sn alloy layer 11 and the back metal layer 12, the adhesive strength between the Sn alloy layer 11 and the back metal layer 12 can be further improved. [Explanation of symbols]

[0038] In the drawing, 10 indicates a sliding member, 11 indicates a Sn alloy layer, 12 indicates a back metal layer, 13 indicates a Sn alloy parent phase, 14 indicates an intermetallic compound, 20 indicates an observed cross section, 21 indicates an interface, 41 indicates an observed region, 51 indicates an Fe-Sn compound, 52 indicates a major axis, 53 indicates an apex, and 61 indicates a rectangular particle.

Claims

1. an Sn alloy layer including a Sn alloy matrix and an Sn-based intermetallic compound dispersed in the Sn alloy matrix; an Fe-based backing metal layer on which the Sn alloy layer is provided on at least one end face side; A sliding member comprising: In an arbitrary observation cross section of the interface between the Sn alloy layer and the back metal layer, the total length of contact between the Sn alloy matrix contained in the Sn alloy layer and the back metal layer is 30% or more relative to the total length of the interface, In the observed cross section, the sum of the areas of the intermetallic compounds with respect to the total area of the Sn alloy layer is 40% or more and 70% or less, When a plurality of visual fields having the same area are arbitrarily extracted from a cross section of the Sn alloy layer, a difference D=A−B between an area percentage A% of a first visual field in which the area percentage of the intermetallic compound is maximum and an area percentage B% of a second visual field in which the area percentage of the intermetallic compound is minimum is within 20%. Sliding member.

2. When a region within 3% of the Sn alloy layer from the interface to the opposite side of the backing metal layer in the thickness direction is set as an observation region, a sum of the areas of the intermetallic compounds relative to the total area of the Sn alloy layer in the observation region is 5% or more and 60% or less; The sliding member according to claim 1.

3. The Sn alloy layer further contains an Fe-Sn compound derived from Sn contained in the Sn alloy layer and Fe contained in the back metal layer, which does not constitute the intermetallic compound; The Fe—Sn compound is The particles rise from the interface toward the Sn alloy layer and are formed in a needle shape having a minor axis and a major axis of 40 μm or less, the distance between the vertices opposite to the interface between adjacent Fe—Sn compounds is 0.5 μm or more; The sliding member according to claim 1.

4. The intermetallic compound includes rectangular grains having a rectangular cross section, The rectangular particles have a center-to-center distance of 10 μm or more between adjacent rectangular particles. The sliding member according to claim 1.

5. The Sn alloy layer has a Vickers hardness of 38 HV or more. The sliding member according to claim 1.

6. The Sn alloy layer is Sb: 3.0 to 12 mass%; 4.0 to 18 mass% Cu, The balance is Sn including unavoidable impurities. The sliding member according to claim 1.

7. A method for manufacturing a slide member according to any one of claims 1 to 6, comprising the steps of: an irradiation step of irradiating one end surface of the back metal layer with laser light; a throwing step of throwing an alloy material for forming the Sn alloy layer into a focus of the laser light irradiated in the irradiation step; an alloy layer forming step of melting the alloy material introduced in the introducing step on the surface of the back metal layer by the irradiated laser light, bonding the alloy material formed by the melting to the back metal layer, and depositing the Sn alloy layer on the back metal layer; Including, A method for manufacturing a sliding member.

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