Copper alloy for sliding member

Abstract

To provide a copper alloy for sliding members containing sulfides as solid lubricants, which prevents segregation of the sulfides and peeling of a sintered layer in a rolling process, without the need for forming an intermediate bronze layer in the base material.SOLUTION: A sliding member is produced by forming a sintered layer through sintering a copper alloy for sliding members on the side of a nickel plating layer of a base material, the base material having the nickel plating layer on its sliding surface, wherein the copper alloy for sliding members contains 3 mass% or more and 20 mass% or less of tin, 0.2 mass% or more and 5.0 mass% or less of sulfur, 5.0 mass% or less of iron, 1.0 mass% or less of phosphorus, and 5.0 mass% or less of carbon, with the balance being copper and inevitable impurities.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a copper alloy for use in a sliding member. [Background technology]

[0002] As a sliding member such as a bearing material, an alloy obtained by sintering copper alloy powder in which sulfides are dispersed is used. Patent Document 1 also discloses a copper alloy for sliding materials containing 1% by mass to 20% by mass of Cu5FeS4 as a solid lubricant, 9% by mass to 11% by mass of Sn, 1.5% by mass to 2.5% by mass of Fe, 0.5% by mass to 2.2% by mass of S, 0.01% by mass to 0.03% by mass of P, and the remainder being Cu and unavoidable impurities. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5902615 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the powder of Patent Document 1 is placed on a steel material and sintered to obtain the sulfide-dispersed copper alloy, it has been confirmed that sulfides, in which the sulfur content in the copper alloy combines with elements such as Fe in the base material, segregate at the interface between the base material and the copper alloy sintered layer. This segregation can cause the copper alloy sintered layer to be insufficiently bonded to the steel material, resulting in peeling of the sintered layer during the subsequent rolling process. To address this issue, a countermeasure has been taken in which an intermediate layer made of sintered bronze powder that does not contain sulfides is first provided on the steel material, and then sulfide-dispersed copper alloy powder is placed on top of that and sintered, thereby preventing the segregation of sulfides to the steel material side (intermediate layer side) and ensuring adhesion.

[0005] However, providing an intermediate layer required an additional sintering step, which posed a problem in terms of productivity.

[0006] Therefore, an object of the present invention is to obtain a sulfide-dispersed copper alloy that prevents peeling of the sintered layer without providing an intermediate layer, thereby increasing the productivity of sliding materials. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides, as a first solution, The copper alloy for a sliding member contains 3% by mass or more and 20% by mass or less of tin, 0.2% by mass or more and 5.0% by mass or less of sulfur, 5.0% by mass or less of iron, 1.0% by mass or less of phosphorus, 5.0% by mass or less of carbon, and the remainder being copper and unavoidable impurities.

[0008] Furthermore, the present invention provides A slide member in which a base material and a sintered layer made of the copper alloy for slide members according to the first solving means are laminated, A second solution can be selected in which the sintered layer is a sliding member having a structure in which nickel is dissolved in the α phase.

[0009] Furthermore, the present invention provides A slide member in which a base material and a sintered layer made of the copper alloy for slide members according to the first or second solving means are laminated, A third solution can be selected in which the sintered layer is a sliding member having a structure in which nickel is dissolved in the δ phase.

[0010] Furthermore, the present invention provides a method for producing a copper alloy for a sliding member, which is the first solution, by: A fourth solution can be selected in which the sliding member has a sintered layer formed by sintering the copper alloy for sliding members on the side of a base material having a nickel plating layer on the sliding side surface.

[0011] Furthermore, in the method for producing a slide member according to the present invention, a configuration can be selected in which a sintered layer is formed by sintering the copper alloy for a slide member, which is the first solving means, on the nickel-plated layer side of a base material having a nickel-plated layer on the sliding side surface. [Effects of the Invention]

[0012] When a sintered layer is provided on a base material provided with a nickel plating layer using the copper alloy for a sliding member having the configuration of the present invention, the generation of sulfides in the vicinity of the interface of the sintered layer can be suppressed, and the adhesion between the sintered layer and the base material can be improved.

[0013] Compared with the conventional intermediate layer made by sintering bronze powder, nickel plating does not require the labor of sintering and can be formed inexpensively. Therefore, nickel-plated steel materials are readily available at low cost, and by forming a layer of the copper alloy for slide members having the above-mentioned configuration on the plated surface by sintering, slide members can be obtained with high productivity. [Brief explanation of the drawings]

[0014] [Figure 1] SEM and EDS images of the vicinity of the interface of the cut surface of the sample with the nickel plating layer of different thicknesses in Example 4 [Figure 2] Figure 1 shows SEM and EDS images of the area 500 μm from the base material interface to the copper alloy side. DETAILED DESCRIPTION OF THE INVENTION

[0015] The copper alloy for a sliding member according to the present invention and a sliding member using the same will be described below. The sliding member is formed by sintering a copper alloy for a sliding member on the nickel-plated layer side of a base material having a nickel-plated layer on the sliding side surface.

[0016] The base material is the base of the sliding member, has the shape required for the sliding member, and has a predetermined surface on the side that slides against other materials. This surface is called the sliding side surface. The base material may be any iron-based material, and from the standpoint of strength, a steel material with a carbon content of 2 mass% or less is desirable. There are no particular restrictions on the type as long as it has the strength required for the application. Since the sulfide that should be prevented from segregating is basically FeS, it is thought that the segregation that the present invention aims to solve will not occur in the first place in a base material that does not contain iron. As an iron-based material used for this base material, for example, S45C can be suitably used.

[0017] The nickel plating layer is present before sintering in the manufacturing stage, but the nickel disperses into the sintered layer during the sintering stage. As a result, the nickel plating layer disappears in the finished sliding member, or if it remains, it is reduced in thickness from its original value. Instead, the sintered layer contains a large amount of diffused nickel near the base material. There is no particular restriction on the method for forming the nickel plating layer during the manufacturing stage, as long as it can be formed to the required thickness. For example, electrolytic plating, electroless plating, etc. can be selected as appropriate depending on the shape and size of the base material and the sliding side surface.

[0018] The thickness of the nickel plating layer before sintering is preferably 0.1 μm or more, and more preferably 0.5 μm or more. If it is less than 0.1 μm, there will not be enough nickel to diffuse, which may result in an insufficient effect of preventing sulfide segregation and suppressing peeling after the rolling process. On the other hand, a thick nickel plating layer provides a large amount of nickel that can be diffused, which is sufficient to prevent sulfide segregation, making it less likely to cause practical problems. Although manufacturing is possible with a thickness of around 100 μm, this will increase costs. For this reason, a thickness of 10 μm or less is preferable.

[0019] Next, the copper alloy for the sliding member used will be described. The copper alloy for the sliding member used in the present invention is a copper alloy containing tin and sulfur within a predetermined range, and may contain iron, phosphorus, and carbon within a predetermined range, with the balance being copper and unavoidable impurities. In particular, compared to systems using molybdenum or tungsten sulfides as the main solid lubricant, systems containing Cu2S or Cu5FeS4 as the main solid lubricant tend to exhibit significant segregation of sulfides near the interface with the base material. Therefore, the effect of suppressing segregation by implementing the present invention is preferably exhibited in systems containing Cu2S or Cu5FeS4 as the solid lubricant.

[0020] The copper alloy must contain 3.0% by mass or more of tin, preferably 6% by mass or more. Tin improves the matrix strength of the copper alloy, improves wear resistance and corrosion resistance, and maintains good sliding properties. If the tin content is less than 3.0% by mass, the melting point becomes too high, reducing sinterability (i.e., bondability to the base material), and the sintered layer may be too soft and unable to conform to the base material. On the other hand, the tin content must be 20.0% by mass or less, preferably 15% by mass or less. If the tin content exceeds 20.0% by mass, the sintered layer becomes too hard and is prone to cracking during the rolling process after sintering. Furthermore, the sintered layer may be prone to melting at high temperatures during formation. Furthermore, if the tin content exceeds 20.0% by mass, there is a risk of deviating from the binary system of copper and tin and generating phases other than the α phase and δ phase, which is undesirable.

[0021] The copper alloys described above are those containing sulfur. Sulfur must be present in an amount of 0.2% by mass or more to form sulfides such as Cu2S and Cu5FeS4, a Cu-Fe-S sulfide, which act as a solid lubricant for the sintered layer. Furthermore, if the sulfur content is too low, segregation of sulfides, which is the cause of the problem to be solved by the present invention, hardly occurs, making the present invention meaningless. The sulfur content must be 5.0% by mass or less, and preferably 3.0% by mass or less. If the sulfur content exceeds 5.0% by mass, there is a high risk that sulfide segregation during sintering will not be sufficiently prevented, even with the interposition of a nickel-plated layer. Furthermore, too much sulfur can cause the sintered layer to become brittle and prone to cracking.

[0022] The copper alloy may contain iron. Iron sulfide is a suitable raw material for supplying sulfur to the copper alloy. Iron forms Cu5FeS4, which acts as a solid lubricant, so a small amount of iron makes the copper alloy suitable for use as a sliding member. On the other hand, if there is no iron or if there is insufficient iron, the copper alloy will form Cu2S, which also acts as a solid lubricant, so iron is not necessarily required. To form Cu5FeS4, the iron content is preferably 0.1% by mass or more, and more preferably 0.3% by mass or more. On the other hand, the iron content must be 5.0% by mass or less, and preferably 2.0% by mass or less. If the iron content exceeds 5.0% by mass, the melting point will be too high, sinterability will be impaired, and it will be difficult to form a sintered layer.

[0023] Since the copper alloy contains iron and sulfur, iron sulfide can be used to prepare the raw materials.

[0024] The copper alloy may contain phosphorus. Phosphorus forms a Cu-P compound with copper, increasing the hardness of the copper alloy as a whole and contributing to its sliding properties. However, the phosphorus content must be 1.0 mass% or less. If the phosphorus content exceeds 1.0 mass%, compounds of iron and phosphorus are likely to be formed at the interface between the copper alloy and the base material, which may actually make the alloy more susceptible to peeling.

[0025] The copper alloy may contain carbon. When the carbon content is 0.1% by mass or more of graphite, it acts as a solid lubricant and can improve the sliding properties of the sintered layer. However, graphite does not dissolve in the copper alloy, and if there is too much graphite, it may cause peeling of the sintered layer or deteriorate the sinterability. Therefore, if carbon is contained, the content is preferably 5.0% by mass or less, and more preferably 3.0% by mass or less.

[0026] The copper alloy preferably contains only copper and unavoidable impurities, in addition to the elements listed above. The lower the content of the unavoidable impurities, the better. Specifically, the content of each element is preferably 0.1% by mass or less, and even more preferably below the detection limit. Examples of such elements include molybdenum, nickel, zinc, and tungsten. However, even if nickel is not present in the original copper alloy or even in very small amounts, it will be present in a detectable amount in the sintered layer due to diffusion from the nickel-plated layer after sintering. Furthermore, the presence of molybdenum or tungsten sulfides may cause defects. Molybdenum disulfide is known to be prone to oxidation and degradation. On the other hand, tungsten disulfide is less likely to deteriorate due to oxidation. However, both molybdenum and tungsten sulfides have poor affinity with the base material. These sulfides exist without solid solution in the copper alloy, which is thought to increase the likelihood of manufacturing defects such as peeling and cracking of the sintered layer during manufacturing. Furthermore, these sulfides, which also serve as solid lubricants, may peel off when used as a sliding component. For this reason, it is preferable that these sulfides are below the detection limit.

[0027] The manufacturing procedure for forming a sintered layer on the nickel-plated layer of a base material using the above copper alloy to form a sliding member is not particularly limited as long as it allows for the favorable formation of a sintered layer on the base material. A material having a nickel-plated layer on the sliding side surface is used as the base material, and a layer of alloy powder prepared so as to satisfy the conditions of the above copper alloy is formed on this nickel-plated layer, and then sintered to form the sintered layer. Sintering does not have to be performed only once, and multiple sinterings may be performed. A rolling step may also be performed after or during sintering. A general method using atomized powder can be used to prepare the powder.

[0028] The temperature for each sintering step is preferably 750°C or higher, and more preferably 800°C or higher. If the temperature is lower than 750°C, the alloy powder may not be sintered sufficiently, and a sintered layer may not be formed. On the other hand, if the temperature is higher than 900°C, there is a risk that the tin will melt rather than sinter, so a temperature of 900°C or lower is preferable.

[0029] Because nickel diffuses from the base material into the sintered layer before it is formed, the nickel plating layer on the finished slide component is reduced or completely eliminated compared to before sintering. Instead, the sintered layer contains diffused nickel. Furthermore, while sulfide segregation occurs near the base material of the sintered layer in slide components made from conventional copper alloys for slide components containing Cu5FeS4, this segregation is suppressed by the diffusion of nickel, and segregated sulfides are not observed or are only observed in very small amounts, preventing peeling of the sintered layer even during rolling after sintering.

[0030] The sliding member using the copper alloy according to the present invention has a sintered layer primarily composed of α and δ phases formed during sintering. However, nickel from the nickel plating layer diffuses into the sintered layer, presumably creating a structure in which the nickel is dissolved in the δ phase (δ phase + Ni). Furthermore, when the tin content is 10 mass% or less, the δ phase may not form. In such a system, a structure in which nickel is dissolved in the α phase is also presumably formed. When the α and δ phases coexist, a structure in which nickel is dissolved in the δ phase is likely to form. The formation of such a structure indicates that nickel diffuses from the interface between the base material and the sintered layer toward the sintered layer. This movement of nickel inhibits the movement of sulfur toward the interface, preventing the segregation of sulfides near the base material and resulting in a sliding member with reduced delamination. Furthermore, the copper alloy according to the present invention contains almost no nickel, and the nickel contained in the sliding member is essentially derived from the nickel plating layer. For this reason, the distribution amount of nickel in the sliding member according to the present invention differs significantly between the vicinity of the interface and the internal region away from the interface (at a distance of several hundred μm or more from the interface on the copper alloy side). Basically, nickel tends to remain near the interface where the nickel plating layer was originally located, so a large amount of dissolved nickel is also easily observed. On the other hand, the sintering time is often insufficient for nickel to reach the internal region, so the amount of nickel in the internal region tends to be less than near the interface.

[0031] In addition, in accordance with the behavior of nickel, in a slide member using the copper alloy according to the present invention, the sintered layer preferably has a sulfur-deficient layer having a lower sulfur content than the average for the copper alloy in a region 50 μm to 200 μm thick from the interface between the base material and the sintered layer. This sulfur-deficient layer preferably has a thickness of 20 μm or more. The fact that the sulfur-deficient layer is sufficiently formed means that the diffusion and solid solution of nickel can prevent segregation of sulfides near the interface, resulting in a slide member that is less likely to peel off even during rolling processes or other situations where loads are applied. [Example]

[0032] Hereinafter, specific examples of the present invention will be described. A piece of S45C steel was cut to a length of 75 mm, width of 75 mm, and thickness of 10 mm to prepare the base material. One of the longitudinal and lateral surfaces was used as the sliding side, and a nickel plating layer was formed to prepare the base material piece. The nickel plating layer was formed by electrolytic plating, with the thicknesses shown below.

[0033] <Verification test of plating thickness> Atomized powder was layered to a thickness of 4 mm on the nickel-plated layers on the longitudinal and lateral surfaces of the base material specimens, each with a plating thickness as shown in Table 1. The mass ratio of the atomized powder was 15 mass% tin, 1.0 mass% sulfur, 0.8 mass% iron, and 0.02 mass% phosphorus, with graphite below the detection limit, and the remainder consisting of copper and unavoidable impurities. Test specimens were produced by sintering for 2 hours in a nitrogen-hydrogen atmosphere in a conveyor furnace (Koyo Thermo Systems Co., Ltd.: AS10A-2) set at a temperature between 800°C and 850°C.

[0034] [Table 1]

[0035] The test pieces were rolled using a roller rolling machine (Amagasaki Kogyosho Co., Ltd.: 1111+2704-5-01, roller diameter 150 mm) with a rolling force of 180 kN, and no peeling of the sintered layer was observed in any of the test pieces. Furthermore, as Reference Example 1, a test piece was prepared having the same composition as Verification Example 1 except that it did not have a nickel plating layer. When the test piece was rolled, peeling of the sintered layer was observed even at 30 kN. Therefore, it was confirmed that the effect of the present invention, which prevents sulfide segregation and peeling of the sintered layer, was achieved when the plating thickness of the nickel plating layer was in the range of 0.5 μm to 100 μm.

[0036] <Manufacturing Test> The same base material pieces as those used in the above verification tests, with a nickel plating layer thickness of 10 μm, were used. Atomized powders prepared to the respective mass ratios shown in Table 2 were layered on the nickel plating layer of these base material pieces to a thickness of 4 mm. Test pieces were prepared by sintering in the same manner as in the verification tests. Examples 1 to 5 varied the tin content. Examples 6 and 7 were based on Example 4, but with increased graphite content. Examples 8 and 9 were based on Example 4, but with decreased sulfur and iron contents. Examples 10 to 12 were based on Example 4, but with increased sulfur content. Examples 13 to 15 were based on Example 4, but with increased iron content. However, since iron sulfide was used as the raw material, the sulfur content also increased. Examples 16 to 19 were based on Example 3, but with increased phosphorus content.

[0037] [Table 2]

[0038] <Quality testing of sintered layers by rolling evaluation> Using the roller rolling machine used in the verification test, the specimens were rolled under loads of 30 kN, 100 kN, and 180 kN, and evaluated for delamination. The results are shown in Table 2. Good adhesion with no delamination of the sintered layer was evaluated as ○, slight delamination was evaluated as ○-, partial delamination or cracking was observed as △, and delamination or cracking occurred throughout the sintered layer was evaluated as ×. Overall evaluation was performed as follows: no delamination even at 180 kN was evaluated as ○, partial delamination was observed at 180 kN but the specimen was held together as a whole as ○-, delamination occurred at 180 kN but not at 100 kN as △, and delamination at 30 kN was evaluated as ×.

[0039] <Sintered layer hardness evaluation> The Rockwell hardness (HRH) of the sintered layer of each example was measured using a Rockwell hardness tester (HR-300 manufactured by Mitutoyo Corporation) in accordance with the Rockwell hardness testing method specified in JIS Z 2245:2016. The values ​​are shown in Table 2. Note that in Examples 1 and 12, the sintered layer peeled severely when rolled under a load of 180 kN, making it impossible to measure. In all other cases, it was confirmed that sufficient hardness values ​​could be secured for the surface of a sliding component.

[0040] <Consideration> Examples 1-5, in which the tin content was varied, confirmed that too little or too much tin tends to insufficiently prevent peeling of the sintered layer, even when combined with the nickel-plated layer. It was confirmed that a tin content of 6 to 15 mass% is preferable. In particular, in Example 1, which was able to withstand up to 100 kN but exhibited peeling at a high rolling load of 180 kN, it is presumed that the alloy's melting point was raised due to the low tin content, making it difficult to bond to the base material. Examples 4, 6, and 7 confirmed that the nickel-plated layer's effect of preventing peeling of the sintered layer can be maintained to a certain extent even when graphite is added to improve sliding properties. Examples 4, 8, and 9 confirmed that reducing the iron and sulfur content naturally further suppresses sulfide segregation, thereby naturally preventing peeling of the sintered layer. However, it is believed that the sliding properties of Examples 8 and 9 are lower than those of Example 4 due to the reduction in the solid lubricant Cu5FeS4. Examples 4, 10, and 12 revealed that excessive sulfur content made the sintered layer more susceptible to peeling, even though the nickel plating layer prevented sulfide segregation. In Example 12, where the sulfur content was 5% by mass, rolling was possible up to a load of 100 kN, which was within the practical range. However, a load of 180 kN reached its limit. Therefore, increasing the sulfur content beyond this range is undesirable, and a sulfur content of 5% by mass or less is considered necessary. To fully utilize the sulfide segregation prevention effect of the nickel plating layer, it is preferable to limit the sulfur content to 3% by mass or less. Examples 4, 13, and 15 suggested that an increase in the iron content would increase the melting point of the alloy, thereby decreasing sinterability. However, it was confirmed that sufficient sinterability was achieved when the sulfur content was 3% by mass or less and the iron content was 5% by mass or less. Furthermore, in Reference Example 2, which used an alloy with the same content as in Example 4 but lacked a nickel plating layer, cracks occurred in the sintered layer even at 30 kN.

[0041] <Behavior check> For the copper alloy having the composition of Example 4, test pieces were prepared with nickel plating layers having thicknesses of 1 μm, 10 μm, 50 μm, and 100 μm. The sintered specimens were cut perpendicular to the interface between the layers, and the cross sections were photographed using an electron microscope (SEM, JEOL Ltd.: JCM-7000). The same cross sections were also observed using energy dispersive X-ray spectroscopy (EDS) using the same equipment as the electron microscope to measure the element distribution in the cross section. These results are shown in Figures 1 and 2. The lower side of each figure is the base material side, and the upper side is the copper alloy side. The horizontal bar in the lower left of each figure corresponds to a length of 50 μm. In Figure 1, the base material is approximately 20 μm from the bottom, and the area above that is the copper alloy layer. As is clear from the SEM images of the specimens with nickel plating thicknesses of 1 μm and 10 μm, the slightly darker areas in the copper alloy layer are the α phase, and the mottled, slightly lighter layers are the δ phase. Figure 2 shows the area 500 μm from the interface with the base material toward the copper alloy layer.

[0042] The samples of the present invention do not allow for direct observation of the behavior of nickel diffusion over time during sintering. Therefore, we utilize the fact that increasing the amount of nickel plating increases the amount of nickel dispersed during sintering. This increases the time it takes for the entire amount of nickel provided by the nickel plating layer to diffuse. In other words, the thinner the nickel plating layer, the faster nickel diffusion is completed, and the thicker the nickel plating layer, the longer it takes for nickel diffusion to be complete. While nickel diffusion is complete in samples with a 10 μm nickel plating layer, observing samples with nickel plating layers increased to 50 μm or 100 μm allows us to understand the situation at an intermediate stage before nickel diffusion is complete.

[0043] Let's examine the behavior of nickel. In Figure 1, in the samples with nickel plating thicknesses of 50 μm and 100 μm, a nickel-rich layer, which represents the state before the nickel plating layer has completely diffused, is still visible. This is evident in the nickel EDS and SEM images. In contrast, in the samples with nickel plating thicknesses of 1 μm and 10 μm, no nickel-rich layer is observed, confirming that the original nickel plating layer has been lost due to diffusion. When observed more than 200 μm away from the interface (Figure 2), the nickel-rich area is observed as a mottled pattern. This is particularly evident in the samples with nickel plating thicknesses of 50 μm and 100 μm. These nickel-rich mottled areas are common to the tin-rich areas, confirming that a structure in which nickel has dissolved in the δ phase has been formed where the nickel has diffused. However, nickel is also observed, albeit thinly, in areas other than the δ phase, confirming that nickel is also dissolved in the α phase.

[0044] Next, let's examine sulfur. In Figure 1, for the samples with nickel plating layers of 50 μm and 100 μm, only a few sulfur-rich regions are observed near the top of the figure, and no sulfur segregation is evident. On the other hand, sulfur begins to accumulate near the interface in the sample with a 10 μm nickel plating layer, and although it accumulates further in the sample with a 1 μm nickel plating layer, it is still fragmented. This suggests that sulfur concentration at the interface and its resulting segregation are suppressed while nickel diffusion is progressing, and that sulfur begins to accumulate once sintering progresses and nickel diffusion is complete. Meanwhile, in the regions approximately 50 to 150 μm away from the interface, no sulfur-rich regions are present, and a sulfur-depleted layer with less sulfur than the other regions is formed over a thickness of approximately 100 μm. This sulfur-depleted layer is clearly visible in Figure 2, which shows regions more than 200 μm away from the interface, where sulfur concentrations (presumably mainly Cu5FeS4, since this matches Fe) are observed in some places. This sulfur-deficient layer corresponds to the area where the nickel plating layer originally existed, which has diffused into the copper alloy. Therefore, it is thought that the diffusion of nickel creates this sulfur-deficient layer, preventing sulfur segregation to the extent that it would cause peeling.

[0045] (Reference examples 3~5) The following copper alloys were used: Reference Example 3, which contained 10% by mass of tin, 0.6% by mass of sulfur, and 0.6% by mass of iron, with the remainder being copper; Reference Example 4, which contained 10% by mass of tin, 1% by mass of sulfur, and 0.8% by mass of iron, with the remainder being copper; and Reference Example 5, which contained 15% by mass of tin, 1.0% by mass of sulfur, and 0.8% by mass of iron, with the remainder being copper. Using these alloys, a sintered layer was formed on the base material, which was the S45C steel used in the examples but did not have a nickel plating layer. In all examples, peeling had already occurred at the end of sintering, before rolling. Therefore, it was confirmed that the nickel in the nickel plating layer formed on the base material in the examples contributed to preventing peeling.

[0046] From the above behavior of sulfur, it was confirmed that it is desirable to shorten the sintering time when the nickel plating layer is thinned in the production of a sliding member, whereas it was confirmed that it is more desirable to prepare a nickel plating layer thick enough to sufficiently prevent sulfur segregation and to ensure a sufficient sintering time so that a structure in which nickel is solid-solved in the δ phase can be formed.

Claims

1. A copper alloy for a sliding member comprising: 3% by mass or more and 20% by mass or less of tin; 0.2% by mass or more and 5.0% by mass or less of sulfur; 5.0% by mass or less of iron; 1.0% by mass or less of phosphorus; and 5.0% by mass or less of carbon, with the balance being copper and unavoidable impurities.

2. A slide member in which a base material and a sintered layer made of the copper alloy for slide member according to claim 1 are laminated, The sintered layer has a structure in which nickel is dissolved in an α phase.

3. A slide member in which a base material and a sintered layer made of the copper alloy for slide members according to claim 1 are laminated together, or the slide member according to claim 2, The sintered layer has a structure in which nickel is dissolved in a δ phase.

4. 10. A sliding member, comprising: a base material having a nickel-plated layer on its sliding side surface; and a sintered layer formed by sintering the copper alloy for sliding members according to claim 1 on the nickel-plated layer side of the base material.

5. 2. A method for producing a sliding member, comprising sintering the copper alloy for sliding members according to claim 1 on the nickel-plated layer side of a base material having a nickel-plated layer on the sliding side surface thereof to form a sintered layer.

Images