Copper-based sliding element

Abstract

Copper-based sliding element (1) comprising brass in which Mn-Si-based compounds are distributed in a brass structure (2), wherein the Mn-Si-based compounds contain particles of needle-shaped Mn-Si-based compounds (3) with lengths of 50 µm or more in the direction of the principal axis, wherein 50% or more of the total number of needle-shaped Mn-Si-based compounds (3) consist of a plurality of segmented particles (4) and wherein the distance between the segmented particles of which the needle-shaped Mn-Si-based compounds consist is 5 µm or less.

Description

Background of the invention(1) Field of the invention

[0001] The present invention relates to a copper-based sliding member having excellent seizure resistance and suitable for a turbocharger of an internal combustion engine. (2) Description of the state of the art

[0002] Radial bearings used in turbochargers of internal combustion engines are traditionally required to have corrosion and wear resistance. According to JP 2003 42145 A, a copper alloy containing Cu, Zn, Al, and Mn-Si-based compounds as the main components is used as the material for radial bearings. In the prior art described in JP 2003 42145 A, crystallized-type Mn-Si-based compounds crystallized in a needle shape extend and disperse in a brass matrix (hereinafter referred to as "needle-shaped Mn-Si-based compounds") in an axial direction of a rotation axis. This can achieve the effect of improving the wear resistance of the radial bearing.

[0003] US 2,145,065 A relates to drawn brass bearing alloys, and in particular to drawn, pre-pressed brass bearing alloys containing an excessively high copper content, and a process for their production. The document describes, in particular, a pre-pressed tube, rod, and the like, whichwhich is cold drawn to precise dimensions and contains a brass consisting of a relatively soft matrix consisting essentially of a copper-zinc solid solution containing visible, dispersed, fragmentary, wear-resistant needles containing manganese silicide crystallized from the alloy liquidus, the brass consisting of not less than about 62% and not more than about 80% copper, an effective fraction of 0.05% up to about 5% silicon, and an effective fraction of 0.05% up to about 5% manganese, the high affinity of manganese for silicon being such that the aforesaid needles are formed in the alpha copper-zinc solid solution and the remainder consists essentially of zinc, the tube, rod or the like being softer and at the same time more wear-resistant than corresponding brass pieces without the aforesaid visible, dispersed, fragmentary needles.

[0004] DE 10 2011 004 856 A1 relates to plain bearings for use in turbochargers of internal combustion engines and, in particular, describes a plain bearing for use in turbochargers of internal combustion engines, which is formed from a copper alloy containing, in mass %, 25 to 45% Zn, 0.3 to 2.0% Si, 1.5 to 6.0% Mn, with the remainder consisting of copper and unavoidable impurities. The plain bearing has a cylindrical shape for supporting a rotating shaft. Crystallized Mn-Si compounds are distributed in a matrix of the copper alloy, wherein the compounds extend in the axial direction of the rotating shaft on a sliding surface of the plain bearing. The crystallized Mn-Si compounds have an average intergrain spacing of 20 to 80 µm. The matrix may contain precipitated Mn-Si compounds in addition to the crystallized Mn-Si compounds. Brief summary of the invention

[0005] However, even if the Mn-Si-based needle-shaped compounds extend and are distributed in the axial direction of the rotation axis as described in JP 2003 42 145 A, there is a risk that if an Mn-Si-based needle-shaped compound is present that is excessively large compared to the size (length in the major axis direction) of the Mn-Si-based needle-shaped compound particles, when the Mn-Si-based needle-shaped compound detaches from the sliding surface during sliding, the Mn-Si-based needle-shaped compound will damage the bearing surface and the shaft surface, ultimately causing seizure, although wear resistance is improved. On the other hand, if the sizes (length in the major axis direction) of all the Mn-Si-based needle-shaped compound particles are too small, sufficient wear resistance cannot be ensured.

[0006] The present invention was made in view of the above-described circumstances. An object of the present invention is to provide a copper-based sliding member that exhibits excellent seizure resistance by controlling the distribution state of the acicular Mn-Si-based compounds crystallized in the brass structure.

[0007] In order to achieve the above object, an embodiment of the present invention is characterized in that, in a copper-based sliding member made of brass in which Mn-Si-based compounds are dispersed in a brass structure, the Mn-Si-based compounds include particles of acicular Mn-Si-based compounds having lengths of 50 μm or more in the direction of the major axis, and 50% or more of the total number of the acicular Mn-Si-based compounds are composed of a plurality of small segmented particles, and the distance between the segmented particles constituting the acicular Mn-Si-based compounds is 5 μm or less.

[0008] Another embodiment of the present invention is characterized in that, in the copper-based sliding member, all of the Mn-Si-based needle-shaped compounds having lengths of 50 µm or more in the direction of the major axis in the copper-based sliding member are composed of a plurality of small segmented particles.

[0009] Another embodiment of the present invention is characterized in that, in the copper-based sliding member, when 70% or more of the total number of the small segmented particles constituting the Mn-Si-based acicular compounds having lengths of 50 µm or more in the major axis direction in the copper-based sliding member, the lengths of the small segmented particles are 45% or less with respect to the major axis direction of the Mn-Si-based acicular compounds having lengths of 50 µm or more in the major axis direction.

[0010] Another embodiment of the present invention is characterized in that in the copper-based sliding member, the copper-based sliding member contains 3 volume % to 50 volume % of the Mn-Si-based needle-shaped compounds having lengths of 50 µm or more in the direction of the major axis.

[0011] Another embodiment of the present invention is characterized in that in the copper-based sliding member, the copper-based sliding member consists of 20 mass% to 45 mass% of Zn, 0.3 mass% to 20 mass% of Si and 1.0 mass% to 6.0 mass% of Mn, and the balance of Cu and inevitable impurities.

[0012] Another embodiment of the present invention is characterized in that in the copper-based sliding member, the copper-based sliding member further contains a total of 0.1 mass% to 5 mass% of at least one element selected from the group consisting of Fe, Al, Ni, Sn, Cr, Ti, Mo, Co, Zr and Sb.

[0013] Another embodiment of the present invention is characterized in that in the copper-based sliding member, the copper-based sliding member further contains a total of 0.1 mass% to 5 mass% of at least one element selected from the group consisting of Pb and Bi.

[0014] The small, segmented particles that make up the needle-shaped Mn-Si-based compounds are also referred to simply as small particles. Brief description of the different views of the drawings Fig.1 is a schematic view showing a copper-based sliding member in which Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction crystallized in a brass structure are composed of a plurality of small particles. Fig. Figure 2 is a schematic view showing a copper-based sliding member in which Mn-Si-based interconnections with lengths of less than 50 µm in the major axis direction are incorporated in a brass structure. Fig. 3 is a view for explaining the formation of a plurality of small particles by segmenting the Mn-Si-based needle-shaped compound in the extrusion of a copper-based sliding member. Fig.4 is a schematic view showing a copper-based sliding member in which all of the Mn-Si-based needle-shaped compounds crystallized in a brass structure are composed of a plurality of small particles. Detailed description of the invention

[0015] In one embodiment of the present invention, Mn-Si-based acicular compounds are dispersed as the Mn-Si-based compounds in a brass structure. The Mn-Si-based acicular compounds are the compounds that contribute to improving wear resistance. The effect of improving wear resistance can be particularly obtained when the length in the major axis direction of the Mn-Si-based acicular compound is 50 μm or more. The Mn-Si-based acicular compounds are formed by crystallizing Mn and Si in the form of acicular particles in the brass structure during casting.

[0016] In one embodiment of the present invention, the Mn-Si-based acicular compounds consist of a plurality of small particles. The plurality of small particles is formed by segmenting the Mn-Si-based acicular compounds by subjecting the copper-based sliding member, in which the Mn-Si-based acicular compounds are distributed, to plastic working at a controlled working ratio.

[0017] In one embodiment of the present invention, as shown in Fig.1, in a copper-based sliding member 1 in which Mn-Si-based needle-shaped compounds 3 are distributed in a brass structure 2, 50% or more of the total number of Mn-Si-based needle-shaped compounds 3 with lengths of 50 μm or more in the major axis direction are composed of a plurality of small particles 4. As a result, even if the Mn-Si-based needle-shaped compounds 3 peel off during sliding, the small particles 4 constituting the Mn-Si-based needle-shaped compounds 3 can peel off. Thus, the frequency of peeling of the coarse Mn-Si-based needle-shaped compounds 3, which damage a shaft and a bearing, is reduced. As a result, seizure hardly occurs.In the copper-based sliding member 1 in which needle-shaped Mn-Si-based compounds 3 are distributed in the brass structure 2, even if not only the needle-shaped Mn-Si-based compounds 3 having lengths of 50 µm or more in the major axis direction but also the Mn-Si-based compounds 5 having lengths of less than 50 µm in the major axis direction are included, as shown in . Fig. As shown in Figure 2, the Mn-Si-based joints 5 with lengths of less than 50 µm in the direction of the major axis do not release harmful foreign substances when they are peeled off during sliding and therefore do not affect the seizure resistance.

[0018] The distance between the small particles constituting the Mn-Si-based needle-shaped joints is 5 μm or less. When the surface distance between the small particles is 5 μm or less, the small particles are not easily detached during sliding, and the shape of the Mn-Si-based needle-shaped joints can be maintained for a long time. When the copper-based sliding member in which the Mn-Si-based needle-shaped joints are distributed is subjected to plastic processing, the Mn-Si-based needle-shaped joints are mainly segmented in the direction perpendicular to the major axis direction. However, it is also allowed for the Mn-Si-based needle-shaped joints to be segmented in the direction parallel to the major axis direction.

[0019] Furthermore, it is confirmed by an experiment that when the copper-based sliding member in which the Mn-Si-based needle-shaped compounds are dispersed is used as a bearing, if the shapes of the Mn-Si-based needle-shaped compounds according to the present invention are configured at least in a region within a depth of 100 μm from the bearing surface, the same effect as described above can be obtained.

[0020] The following describes a method for controlling the distribution state of the Mn-Si-based acicular compounds crystallized in the brass structure. Regarding the size of the Mn-Si-based acicular compounds, the length in the major axis direction can be controlled to 50 μm or more through the casting conditions. After casting, when the blank is extruded into a rod-like semi-finished product with a predetermined shape, the Mn-Si-based acicular compounds can be segmented into a plurality of small particles by controlling the machining ratio.The reason for this is that the amount of plastic deformation B of the Mn-Si-based needle-shaped compounds 3 is small compared to the amount of plastic deformation of the brass structure 2 in the extrusion of the copper-based sliding member in which the Mn-Si-based needle-shaped compounds 3 are distributed in the brass structure 2 as shown in . Fig. 3. However, the Mn-Si-based interconnects with major axis lengths of less than 50 µm distributed in the copper-based sliding member may or may not be segmented.

[0021] As long as a machining process such as drawing and forging is used, which causes plastic deformation inside the cast blank, the shape of the Mn-Si-based needle-shaped compounds according to the present invention can be achieved by controlling the machining ratio. Therefore, the machining process is not limited to extrusion.

[0022] In a further embodiment of the present invention, all of the Mn-Si-based needle-shaped compounds having lengths of 50 µm or more in the direction of the major axis are composed of a plurality of small particles in the copper-based sliding member 1 in which the Mn-Si-based needle-shaped compounds 3 are distributed in the brass structure 2, as shown in Fig.4. As a result, seizure hardly occurs even if the Mn-Si-based needle-shaped compounds 3 peel off during sliding. This is because no Mn-Si-based needle-shaped compounds 3 with lengths of 50 μm or more in the major axis direction that are not composed of a plurality of small particles 4 are included, and the frequency of peeling off of the coarse Mn-Si-based needle-shaped compounds 3, which damage the shaft and the bearing, is more reduced.

[0023] In another embodiment of the present invention, in the copper-based sliding member in which Mn-Si-based needle-shaped compounds are dispersed in the brass structure, in 70% or more of the total number of small particles constituting the Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction, the length of the small particles is 45 μm or less with respect to the major axis direction of the Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction. Therefore, seizure hardly occurs even if the Mn-Si-based needle-shaped compounds peel off during sliding.The reason is that the small particles with lengths of 45 μm or less with respect to the direction of the major axis of the Mn-Si-based needle-shaped compounds can peel off, and the frequency of peeling off of the coarse Mn-Si-based needle-shaped compounds that damage the shaft and the bearing is more reduced.

[0024] In another embodiment of the present invention, in the copper-based sliding member in which the Mn-Si-based needle-shaped compounds are distributed in the brass structure, 3 vol% to 50 vol% of the Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction are contained. This achieves favorable wear resistance. If the amount of the Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction exceeds 50 vol%, this causes a state in which the Mn-Si-based needle-shaped compounds are excessively crystallized in the brass structure, and the material becomes too hard. On the other hand, if the Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction account for less than 3 vol%, the effect of improving wear resistance is insufficient.

[0025] In another embodiment of the present invention, the copper-based sliding member consists of 20 mass% to 45 mass% of Zn, 0.3 mass% to 2.0 mass% of Si, and 1.0 mass% to 6.0 mass% of Mn, with the remainder being Cu and unavoidable impurities. Zn is the element that contributes to corrosion resistance, and 20 to 45 mass% of Zn is contained. With less than 20 mass% of Zn, corrosion resistance in a high-temperature environment is insufficient. If Zn is more than 45 mass%, the material becomes too hard. The Zn content is more preferably in the range of 28 to 40 mass%.

[0026] Si is the element that reacts with Mn to form a Mn-Si-based compound, which contributes to improving sliding properties. Si content ranges from 0.3 to 2.0 mass%. At less than 0.3 mass%, the amount of Mn-Si-based compounds formed is small, and the effect of improving sliding properties is insufficient. If Si content exceeds 2.0 mass%, the material becomes too hard. The Si content is more preferably in the range of 0.6 to 1.2 mass%.

[0027] Mn is the element that reacts with Si to form the Mn-Si-based compound, which contributes to the sliding property. It contains 1.0 to 6.0 mass% of Mn. At less than 1.0 mass% of Mn, the amount of Mn-Si-based compounds formed is small, and therefore, the effect of improving the sliding property becomes insufficient. If Mn exceeds 6.0 mass%, the material becomes too hard. The Mn content is more preferably in the range of 2.0 to 4.0 mass%.

[0028] In another embodiment of the present invention, the copper-based sliding member may further contain a total of 0.1 mass % to 5 mass % of at least one element selected from the group consisting of Fe, Al, Ni, Sn, Cr, Ti, Mo, Co, Zr, and Sb. These elements are the elements that contribute to strengthening the matrix of the copper-based sliding member. With less than 0.1 mass % of the elements, the material becomes too soft. If the content of the elements exceeds 5 mass %, the material becomes too hard. Furthermore, these elements combine with Mn and Si to sometimes form compounds. The Mn-Si-based acicular compounds in the present invention may be compounds formed with the above-mentioned elements.

[0029] In another embodiment of the present invention, the copper-based sliding member may further contain a total of 0.1 mass% to 5 mass% of at least one element selected from the group consisting of Pb and Bi. These elements are the elements that contribute to improving lubricity. If these elements are present in less than 0.1 mass%, the lubricity-enhancing effect is insufficient. If the elements exceed 5 mass%, the material becomes too hard.

[0030] The following explains a manufacturing method for examples using a copper-based sliding member in which Mn-Si-based acicular compounds according to the present invention are dispersed, and for comparative examples. First, casting was performed with a predetermined chemical composition, and Mn-Si-based acicular compounds were crystallized in the copper-based sliding member. Subsequently, extrusion, drawing, or forging was applied to the cast copper alloy blank. The dispersal state of the Mn-Si-based acicular compounds was further controlled by controlling the cooling temperature during casting and the working ratio during hot working.Specifically, in the examples, the cast blanks were gradually cooled and solidified, so that the lengths in the major axis direction of numerous Mn-Si-based acicular compounds increased to 50 µm or more, and the hot-working ratios were higher than those of the conventional product. As a result, the Mn-Si-based acicular compounds with lengths of 50 µm or more in the major axis direction were segmented into a plurality of small particles.Furthermore, in the comparative examples, the cast blanks were gradually cooled to solidify them so that the lengths in the major axis direction of numerous Mn-Si-based acicular compounds increased to 50 μm or more, as in the examples, and the machining ratios in hot working were low, as in the conventional product, so that the Mn-Si-based acicular compounds with lengths of 50 μm or more in the major axis direction were not segmented into a plurality of small particles.

[0031] The distribution states of the Mn-Si-based acicular compounds described above are measured by photographing composition images of sections in the direction perpendicular to the extrusion direction, the drawing direction, or the forging direction in the copper-based sliding members at 500× magnification and using a conventional image analysis method based on the obtained composition images (analysis software: Image-ProPlus (Version 4.5); manufactured by Planetron Co.) or the like.

[0032] With respect to Examples A and B, which used copper-based sliding members in which the Mn-Si-based acicular compounds according to the present invention were dispersed, and Comparative Example A, a wear test was conducted using a bearing testing machine. Table 1 shows the conditions of the wear test. Table 2 shows the chemical compositions of Examples A and B and Comparative Example A, the parameters related to the dispersal state of the Mn-Si-based acicular compounds, and the degree of wear. Under "AVERAGE LONG DIAMETER OF ACNE-SHAPED PARTICLES" in Table 2, the average value of the maximum Feret diameter of the Mn-Si-based acicular compounds with lengths of 50 μm or more in the major axis direction is shown.Furthermore, "Volume % of Needle-Shaped Particles" indicates the measurement result of measuring the percentage area of ​​Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction with respect to the observation field of view, because the surface and interior of the copper-based sliding member have equivalent distribution states. Furthermore, "Ratio of the Number of Segmented Needle-Shaped Particles" indicates the measurement result of measuring the ratio of Mn-Si-based needle-shaped compounds segmented into a plurality of small particles with respect to the total number of Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction within the observation field of view.Furthermore, the value calculated from the difference between the thickness before and after the wear test by measuring the thickness of the specimen before and after the wear test is given under “DEGREE OF WEAR”. [Table 1] TEST PROCEDURES BEARING SHELL TEST BEARING INNER DIAMETER 20 mm ORBITAL SPEED 0.1 m / s TEST DURATION 8 HOURS LOAD 10 MPa LUBRICANT OIL ENGINE OIL LUBRICANT OIL TEMPERATURE 120°C

[0033] In each of Examples A and B and Comparative Example A, the lengths in the major axis direction of the Mn-Si-based needle-shaped compounds are 50 μm or more, and 3 to 50 volume % of the Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction are contained in the copper-based sliding member. In each of Examples A and B, 50% or more of the total number of Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction are segmented into a plurality of small particles. In contrast, in Comparative Example A, the Mn-Si-based needle-shaped compounds are not segmented like the conventional product. In the wear test, Examples A and B exhibit wear resistance equivalent to that of Comparative Example A, as shown in Table 2.

[0034] Furthermore, with respect to Examples A to F, which used a copper-based sliding member in which the Mn-Si-based acicular compounds according to the present invention were dispersed, and Comparative Examples A to E, a seizure test was conducted using a bearing testing machine. Table 3 shows the conditions of the seizure test. Examples A and B are the same as Examples A and B subjected to the wear test, and Comparative Example C is the same as Comparative Example A subjected to the wear test. Table 4 shows the chemical compositions of Examples A to F and Comparative Examples A to E, the parameters related to the dispersal state of the Mn-Si-based acicular compounds, and the seizure resistance.The "Average Long Diameter of Needle-Shaped Particles," "Volume % of Needle-Shaped Particles," and "Ratio of Number of Segmented Needle-Shaped Particles" are the same values ​​as those in the wear test. Furthermore, the "Ratio of Number of Small Particles of 45 µm or Less" is the measurement result of measuring the ratio of small particles with lengths of 45 µm or less in the major axis direction to the total number of small particles constituting the Mn-Si-based needle-shaped compounds with lengths of 50 µm or more in the major axis direction, within the measurement field of view. Furthermore, the "Seizure Resistance" is the average value of the maximum contact pressure without seizure. [Table 3] TEST PROCEDURES BEARING SHELL TEST BEARING INNER DIAMETER 20mm ORBITAL SPEED 12 m / s LOAD ACCUMULATED LOAD (3 MPa / 10 min) LUBRICANT OIL ENGINE OIL LUBRICANT OIL TEMPERATURE 120°C

[0035] In each of Examples A to F and Comparative Examples A to E, the lengths in the major axis direction of the Mn-Si-based needle-shaped compounds are 50 μm or more, and 3 to 50 volume % of the Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction are included in the copper-based sliding member, except for Comparative Example D. In each of Examples A to F, 50% or more of the total number of Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction are segmented into a plurality of small particles. In contrast, in each of Comparative Examples A to E, the Mn-Si-based needle-shaped compounds are not segmented like the conventional product. In the seizure test, Examples A to F showed excellent seizure resistance compared to Comparative Examples A to E, as shown in Table 4.

[0036] Furthermore, in each of Examples A to F, since the "ratio of the number of segmented needle-shaped particles" and "ratio of the number of small particles of 45 μm or less" are higher, more excellent seizure resistance is obtained. Specifically, Examples C to F, in which all of the Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the major axis direction are segmented into small particles, are excellent in seizure resistance compared to Examples A and B, which contain needle-shaped Mn-Si-based compounds that are not segmented into a plurality of small particles.Furthermore, Examples C to F, in each of which 70% or more of the total number of small particles constituting the Mn-Si-based acicular compounds having lengths of 50 µm or more in the major axis direction are segmented into small particles having lengths of 45 µm or less in the major axis direction, are excellent in seizure resistance compared with Examples A to B in each of which the ratio of the number of small particles having lengths of 45 µm in the major axis direction is small.Particularly, among Examples C to F, Examples D to F, in each of which all of the total number of small particles constituting the acicular Mn-Si-based compounds having lengths of 50 µm or more in the major axis direction are segmented into small particles having lengths of 45 µm or less in the major axis direction, are more excellent in seizure resistance compared with Example C containing small particles not segmented into particles having lengths of 45 µm or less in the major axis direction.

[0037] Furthermore, in Example F, 2.4 mass% Al, 0.1 mass% Fe, and 0.5 mass% Bi are added to the copper-based sliding member, and Example F is more excellent in seizure resistance than Examples A to D, to which these elements were not added. Experimentally, it is confirmed that the same effect can be obtained by adding elements such as Ni, Sn, Cr, Ti, Mo, Co, Zr, Sb, and Pb, which are different from the elements added to Example F.

[0038] Furthermore, in each of Comparative Examples A to E, since the "Ratio of the Number of Segmented Needle-Shaped Particles" and "Ratio of the Number of Small Particles of 45 μm or Less" were lower, the seizure resistance was lower, and scratches tended to be visible on the shaft and bearing surface after the seizure test. This is believed to be caused by the increased frequency of delamination of coarse needle-shaped Mn-Si-based compounds, which damage the shaft and bearing surface when Mn-Si-based compounds delaminate during sliding.

[0039] Furthermore, in Comparative Example E, as in Example F, 2.4 mass% Al, 0.1 mass% Fe, and 0.5 mass% Bi were added to the copper-based sliding member. However, the seizure resistance was not improved. Experimentally, it is confirmed that even when elements such as Ni, Sn, Cr, Ti, Mo, Co, Zr, Sb, and Pb were added, which are different from those added to Comparative Example E, the seizure resistance was not improved.

[0040] From the results described above, it is confirmed that the seizure resistance is excellent when the distribution state of the Mn-Si-based needle-shaped compounds is optimal, such as in the case where 50% or more of the total number of the Mn-Si-based needle-shaped compounds with lengths of 50 μm or more in the direction of the major axis are formed by a plurality of small particles.

Claims

[1] A copper-based sliding member (1) comprising brass in which Mn-Si-based compounds are distributed in a brass structure (2), the Mn-Si-based compounds containing particles of acicular Mn-Si-based compounds (3) having lengths of 50 µm or more in the direction of the major axis, 50% or more of the total number of the acicular Mn-Si-based compounds (3) being composed of a plurality of segmented particles (4), and the pitch between the segmented particles constituting the acicular Mn-Si-based compounds being 5 µm or less. [2] A copper-based sliding member according to claim 1, wherein all of the Mn-Si-based needle-shaped compounds (3) having lengths of 50 µm or more in the direction of the major axis in the copper-based sliding member (1) are composed of a plurality of segmented particles (4). [3] The copper-based sliding member according to claim 1 or 2, wherein, in 70% or more of the total number of the segmented particles (4) constituting the Mn-Si-based acicular compounds (3) having lengths of 50 µm or more in the major axis direction in the copper-based sliding member (1), the lengths of the segmented particles (4) are 45 µm or less with respect to the major axis direction of the Mn-Si-based acicular compounds (3) having lengths of 50 µm or more in the major axis direction. [4] A copper-based sliding member according to any one of claims 1 to 3, wherein the copper-based sliding member (1) contains 3% to 50% by volume of the Mn-Si-based needle-shaped compounds (3) having lengths of 50 µm or more in the direction of the major axis. [5] A copper-based sliding member according to any one of claims 1 to 4, wherein the copper-based sliding member (1) consists of 20 mass% to 45 mass% Zn, 0.3 mass% to 2.0 mass% Si, and 1.0 mass% to 6.0 mass% Mn, and the remainder of copper and unavoidable impurities. [6] A copper-based sliding member according to any one of claims 1 to 5, wherein the copper-based sliding member (1) further contains a total of 0.1 mass% to 5 mass% of at least one element selected from the group consisting of Fe, Al, Ni, Sn, Cr, Ti, Mo, Co, Zr and Sb. [7] A copper-based sliding member according to any one of claims 1 to 6, wherein the copper-based sliding member (1) further contains a total of 0.1 mass% to 5 mass% of at least one element selected from the group consisting of Pb and Bi.

Images