TW202400816A - Copper-based sliding member containing 1.5 to 10.0 mass% of Sn, and remaining being Cu and impurities - Google Patents

Abstract

A sliding member of the present invention comprises a bearing alloy made of Cu-Sn alloy. The Cu-Sn alloy contains 1.5 to 10.0 mass% of Sn and remaining is Cu and impurities. Observed from a profile perpendicular to a sliding surface, there exist a distribution of high-tin concentration areas. The Sn concentration in the high-tin concentration areas is 1.1 times more than the average Sn concentration of the Cu-Sn alloy, and the area of the high-tin concentration areas is more than 500[mu]m2. The number of the high-tin concentration areas is 5 to 93 per 1 mm2.

Description

Copper sliding components

The present invention relates broadly to copper-based sliding components, and in particular to sliding components including bearing alloys containing Cu-Sn alloys.

Cu-Sn alloys are widely used as bearing alloys due to their high strength and excellent wear resistance. In recent years, with the increase in engine power and the reduction in bearing area due to engine downsizing, the bearing load has increased, and further improvements in the wear resistance of sliding materials have been required. Conventional measures for improving wear resistance include those described in Patent Document 1 and Patent Document 2, for example.

The copper alloy disclosed in Patent Document 1 makes Ag, Sn, Sb, In, Mn, Fe, Bi, Zn, Ni and/or Cr solid-solubilize in the Cu matrix, so that the secondary phases of these elements are not substantially eliminated. form. These added elements solidly dissolved in the Cu matrix move to the lining surface in parallel with the generation of frictional heat and changes in the surface structure of the lining, forming a locally concentrated layer of added elements. The concentrated layer further interacts with the lining in the lubricating oil. The sulfur-based additives react to form sulfur-based compounds, and the oxygen in the lubricating oil reacts with the added elements to form oxygen-based compounds. The solid lubrication effect of the concentrated layer and sulfur-based compounds is excellent, and its sliding characteristics are still excellent even under high surface pressure, thereby having the effect of reducing the amount of wear.

The bearing alloy of the sliding bearing disclosed in Patent Document 2 is characterized in that the concentration of dispersed fine components (such as Sn) continuously decreases from the top range of the bearing metal of the sliding bearing toward the divided surface range. The large tin ratio range is used to ensure the high load-bearing capacity of sliding elements.

However, in Patent Document 1, since the abrasion has progressed before the concentrated layer of solid solution strengthening elements is formed, the abrasion resistance is insufficient in applications where the amount of abrasion is large. According to Patent Document 2, if only the top range that mainly bears the load is considered, the top range that mainly bears the load only has the same wear resistance as other prior art technologies. In addition, the part with a low Sn concentration cannot be used as the main load part, and is not suitable for applications where the load direction is changed or where the bearing has a flat plate shape. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 9-249924 [Patent Document 2] Japanese Patent Application Publication No. 2000-27866

[Problem to be solved by the invention]

An object of the present invention is to provide a sliding member including a bearing alloy containing Cu-Sn alloy, which has a new structure that can improve wear resistance. [Technical means to solve problems]

One aspect of the present invention is to provide a sliding member that has a sliding surface and includes a bearing alloy containing a Cu-Sn alloy containing Sn: 1.5 to 10.0 mass %, and the remainder is Cu. and impurities. When viewed from a cross section perpendicular to the sliding surface, high tin concentration areas are dispersed. The high tin concentration areas have a tin concentration that is 1.1 times or more of the average Sn concentration of the Cu-Sn alloy (hereinafter also referred to as "Sn component"). And the area is 500μm ² or more, and the number of high tin concentration areas is 5 to 93 per 1mm ² .

Sn in the Cu-Sn alloy is preferably 8.0% by mass or less. In addition, Sn in the Cu-Sn alloy is preferably 2.0% by mass or more. The Cu-Sn alloy may further contain either one or both of Ni: 0 to 5.0 mass% and P: 0 to 1.0 mass%.

According to a specific example of the present invention, when viewed from a cross section perpendicular to the sliding surface, the area ratio of the high tin concentration area is 5 to 47%.

According to a specific example of the present invention, the bearing alloy may further contain any one or both of solid lubricant particles and hard particles. The solid lubricant particles preferably include graphite particles, or are graphite. The hard particles preferably include SiC particles, or are SiC particles.

According to another aspect of the present invention, a sliding member is provided, which is provided with a backing layer and a bearing alloy layer on the backing layer, and the bearing alloy layer includes the above-mentioned bearing alloy.

According to a specific example of the present invention, the sliding member is a sliding bearing.

According to another aspect of the present invention, a bearing device including the above-mentioned sliding member is provided.

The present invention and its many advantages are described in detail below with reference to the accompanying schematic drawings. The drawings, for purposes of illustration, show several non-limiting embodiments.

The sliding member of the present invention relates to a sliding member including a Cu—Sn alloy as a bearing alloy. This sliding member is applied to sliding bearings such as journal bearings and thrust bearings used in bearing parts of internal combustion engines and automatic transmissions for passenger cars, for example. For example, the sliding member may be a journal bearing that is formed into a cylindrical shape, or a pair of members that are formed into a semi-cylindrical shape may be combined to form a cylindrical sliding bearing. In terms of the thrust bearing, it can be made into a sliding bearing shaped into a circular ring, or a pair of members shaped into a semicircular ring shape can be combined to make a circular ring shaped bearing. However, the sliding member may have other shapes, and may be used as a sliding member other than a sliding bearing. For example, it can also be used as a flat plate-shaped sliding plate in a reciprocating sliding part of an industrial machine in a grease lubrication environment. Bearing devices including such sliding members are also objects of the present invention.

Next, a structural example of the sliding member 1 according to a specific example of the present invention will be described. Referring to FIG. 1 , a bearing alloy layer 2 is provided on the backing layer 4 . However, the backing layer 4 is an arbitrary element, and only the bearing alloy layer 2 may be provided without the backing layer 4 . The surface of the bearing alloy layer 2 becomes the sliding surface 3 . As an optional option, an overlay may be provided on the bearing alloy layer 2 . In this case, the surface of the bearing alloy layer 2 will be referred to as the sliding surface 3 in this specification.

The backing layer 4 is provided to increase the strength of the sliding member 1 . Although not particularly limited, a metal plate such as steel, Fe alloy, Cu, or Cu alloy can be used for the backing layer 4. As the iron-based material, for example, hypoeutectoid steel, Waston iron-based stainless steel, and ferrous iron are preferred. It is a plate of a predetermined size of Fe alloy such as stainless steel.

As an optional option, a coating layer may be provided on the bearing alloy layer 2 . The coating layer can use: Bi, Sn, Pb, Ag and other metals used to improve the running-in properties of the surface of the sliding layer, or alloys based on these metals or synthetic resins as the main body, etc. It can be a well-known coating layer. The formation method can also use a well-known method.

As an optional option, an intermediate layer can also be provided between the backing layer 4 and the bearing alloy layer 2 . For example, by providing a porous metal layer or an intermediate layer on the surface of the backing layer, that is, on the side of the backing layer that serves as the interface with the bearing alloy layer, the joint strength of the sliding layer and the backing layer can be improved.

The bearing alloy layer includes a bearing alloy composed of Cu-Sn alloy. FIG. 2 shows a cross-sectional view of the sliding member 1 according to a specific example of the present invention. This cross-sectional view is taken from a plane perpendicular to the sliding surface. As shown in FIG. 2 , in the matrix 8 of the Cu-Sn alloy, high tin concentration regions 6 with a relatively large Sn concentration are dispersed. The high tin concentration region 6 can be defined as a region having a Sn concentration that is 1.1 times or more relative to the average Sn concentration of the Cu—Sn alloy, and an area of 500 μm ² or more. Even a region with a Sn concentration of 1.1 times or more is not included in the high tin concentration region 6 if its area is less than 500 μm ² . In the Cu-Sn alloy of the present invention, the number of high tin concentration regions 6 is 5 to 93 per 1 mm ² . The term "average Sn concentration of Cu-Sn alloy" is used to express the average Sn concentration in Cu-Sn alloy because there are high tin concentration areas 6 and so on and there is uneven Sn concentration in Cu-Sn alloy. . In the present invention, its numerical value is considered to be equal to the Sn component of the Cu-Sn alloy.

The high tin concentration area 6 with a large Sn concentration is relatively hard and has high wear resistance. When Sn is uniformly dissolved in the Cu-Sn alloy, the Cu-Sn alloy as a whole bears the load. However, even if it is a Cu-Sn alloy with the same composition, the relatively hard high tin concentration regions 6 are dispersed in the soft matrix 8, and the high tin concentration regions 6 are mainly used to support the other side, thereby making the whole surface becomes difficult to wear. As a result, even if the average Sn concentration is the same, the wear resistance can be improved compared with the case where Sn is uniformly dissolved. Furthermore, regardless of the depth, the cross section perpendicular to the sliding surface becomes the above-mentioned structure, that is, the high tin concentration region 6 still exists in the depth direction, and high wear resistance can be maintained even if wear progresses.

It is preferable that the Cu-Sn alloy of the sliding member of the present invention has Sn dissolved in Cu so that a secondary phase (intermetallic compound) is not substantially formed. The Cu-Sn secondary phase (intermetallic compound) has high hardness and brittleness (brittleness), and is easy to break and fall off. The fragments of the secondary phase after falling off will enter between the sliding surface and the opposite surface, causing damage to the sliding surface and accelerating wear. . Therefore, improvement in wear resistance may be hindered. Regarding the fact that the secondary phase does not substantially exist in the Cu-Sn alloy, as long as there is no secondary phase with an area of 3 μm² or more, it is considered to be "substantially non-existent". Whether the secondary phase with an area of 3 μm² or more exists is confirmed using an electron microscope set to a magnification of 100 times or more.

The Cu-Sn alloy system contains Sn: 1.5~10.0% by mass, and the remainder is Cu and impurities. When the Sn content is less than 1.5% by mass, the hardness cannot be increased to the extent that wear resistance can be obtained. In order to have hardness capable of obtaining wear resistance, the minimum Sn content is preferably 2.0% by mass. Furthermore, the minimum value of Sn content is more preferably 3.0% by mass. If the Sn content exceeds 10.0% by mass, the possibility of forming a Cu-Sn secondary phase is high. In order to reliably reduce the possibility of forming a secondary phase, the maximum Sn content is preferably 8.0% by mass. The maximum Sn content is more preferably 6.5% by mass.

The Cu-Sn alloy may further contain either one or both of Ni: 0 to 5.0 mass% and P: 0 to 1.0 mass%. If these elements are contained within the above range, corrosion resistance can be improved and sintering properties can be easily improved. If 0~5.0 mass% Ni is added, the strength will increase and the wear resistance can be improved. However, if more than 5.0% by mass of Ni is added, the sintering temperature will become higher, resulting in an increase in cost. By adding 0 to 1.0% by mass of P, the sinterability is improved, so the strength is increased and the wear resistance can be improved. However, if more than 1.0% by mass of P is added, sintering proceeds excessively and becomes difficult to control.

In the Cu-Sn alloy, when viewed from a cross section perpendicular to the sliding surface 3, the area ratio of the high tin concentration region 6 is preferably 5 to 47%. When the area ratio of the high tin concentration region 6 is 5% or more, the above effects can be effectively exerted. If the area ratio is 47% or less, the stability of the sintering process can be ensured without compromising the strength of the bearing alloy layer, making it easy to A bearing alloy layer with the desired wear resistance is obtained.

The area of the high tin concentration region 6 is 500 μm ² or more. Even if the area has an Sn content that is 1.1 times or more relative to the Sn content of the Cu-Sn alloy, if the area is less than 500 μm ² , it is not included in the high tin concentration area 6 . This is because if the area is so small, the effect of bearing the load is not good, and it does not help improve the wear resistance.

In the Cu-Sn alloy of the present invention, the number of high tin concentration regions 6 is 5 to 93 per 1 mm ² . When the number of high tin concentration areas 6 is less than 5 per 1 mm ² , the above effect cannot be exerted. When the number exceeds 93, the tin concentration tends to become uniform, and it may not be possible to obtain an area of 500 μm ² or more and a function of 1.1 times or more. The tin concentration mainly supports the high tin concentration area on the opposite side. In order to produce a bearing alloy layer with more than 93 high tin concentration areas, the particle size of the copper-tin alloy powder must be further reduced during production. In this case, if the particle size of the copper-tin alloy powder is too small, Sn will easily diffuse during the sintering process. Therefore, the degree of Sn diffusion cannot be stably controlled in the sintering process, and the high tin concentration region 6 cannot be stably formed.

As a preferred specific example, the area ratio of a region where the Sn concentration is 1.2 times the Sn content of the Cu-Sn alloy (hereinafter referred to as the "region of 1.2 times the threshold value", etc.) is 5 to 42%. More preferably, the area ratio of the area 1.3 times the threshold is 5~35%. Particularly preferably, the area ratio of the area 1.4 times the threshold is 5~26%. With this configuration, it is easier to obtain the above effects.

As a preferred specific example, the number of areas with 1.2 times the threshold value is 5 to 84 areas/mm ² . More preferably, the number of areas 1.3 times the threshold is 5 to 61/mm ² . Particularly preferably, the number of areas 1.4 times the threshold is 5 to 54/mm ² . With this configuration, it is easier to obtain the above effects.

As an optional option, the bearing alloy layer 2 may further contain 0.1 to 12.0% by mass of one or more solid lubricant particles selected from, for example, MoS ₂ , WS ₂ , graphite, and h-BN (hexagonal boron nitride). The solid lubricant preferably contains graphite. More preferably, the solid lubricant is graphite. 0.1~12.0 mass% solid lubricant can be dispersed in the Cu-Sn alloy base material to improve the lubricity and further improve the wear resistance. However, if the solid lubricant exceeds 12.0% by mass, the sintering property may be inhibited.

As an optional option, the bearing alloy layer 2 may further contain: for example, one or more hard particles selected from the group consisting of SiC, Al ₂ O ₃ , SiO ₂ , AlN, Mo ₂ C, WC, Fe ₂ P, and Fe ₃ P, in total 0.1 ~5.0 mass%. The hard particles preferably contain SiC. More preferably, the hard particles are SiC. 0.1~5.0% by mass of hard particles can be dispersed in the base material to further improve the wear resistance. However, if the hard particles exceed 5.0% by mass, the sinterability may be inhibited.

Next, a method for manufacturing the bearing alloy layer (Cu-Sn alloy) of the sliding member of the present invention will be described. The manufacturing method includes the following steps. 1. Prepare copper-tin alloy powder and pure copper powder containing a predetermined amount of Sn. When one or both of Ni and P are optionally contained, copper powder containing this element is used instead of the copper-tin alloy powder (this case is also referred to as "copper-tin alloy powder" below). 2. Weigh the copper-tin alloy powder and pure copper powder so that the Sn component becomes a predetermined value (Sn is 1.5 to 10.0 mass %) (if Ni and P are optionally included, it is below the predetermined limit). 3. Mix the weighed copper-tin alloy powder and pure copper powder. At this time, when either or both of solid lubricant particles and hard particles are further included as an optional option, these particles are also added. 4. Spread the mixed powder on the substrate. For example, when forming a bearing alloy layer on a backing pad, the base material is the backing pad. 5. Sinter the dispersed powder at 800℃~900℃ for 10~31 minutes. 6. Roll the sintered body until the sintered body reaches a predetermined thickness. 7. The sintered body having a predetermined thickness is further sintered at 800℃~900℃ for 10~31 minutes.

Under the above sintering conditions, Sn in the copper-tin alloy powder will diffuse into the pure copper powder. However, the sintering does not proceed to the extent that Sn diffuses uniformly throughout the alloy. Instead, the Sn concentration is formed centered on the area where the copper-tin alloy powder was originally. larger area. By adjusting the particle size of the copper-tin alloy powder, the Sn concentration, and the sintering conditions within the above ranges, the area ratio of the high tin concentration region and the number per unit area can be adjusted.

The Sn content of the copper-tin alloy powder used as the raw material is preferably 3 to 15% by mass, and the average particle size is preferably 10 to 75 μm. For example, although pure tin powder can be used instead of copper-tin alloy powder to form a portion with a high Sn concentration, a brittle secondary phase will be formed, so the wear resistance may not be improved.

Next, the measurement method for the high tin concentration area will be explained. The high tin concentration area 6 is determined by using SEM-EPMA to conduct surface analysis on the cross section of the bearing alloy layer 2 perpendicular to the sliding surface 3, and determines a tin concentration that is more than 1.1 times the average Sn concentration of the Cu-Sn alloy. Tin concentration area. Examples of measurement conditions are shown in Table 1. The map obtained by surface analysis is expressed as a concentration using a calibration curve (standard conditions), filtered with a median filter, and binarized. Furthermore, the Sn concentration area having an area of 500 μm ² or more is determined as a high tin concentration area. The threshold and analysis of high tin concentration areas must be performed in areas above ^0.5mm2 .

【Table 1】 Analysis device FE-EPMA (Japan Electronics Co., Ltd. JXA-8530F) Analytical method Face analysis using WDS Analysis area size 800μm×800μm(=400pix×400pix) Analysis point size 2μm×2μm Analyze elements Sn Microcrystals used PETH accelerating voltage 15kV Irradiation current 1× ^{10-8 A} Irradiation time 30ms/pix Scan direction One-way scanning [Example]

Each sample shown in Table 4 to Table 6 was produced by the manufacturing method described above. Copper-tin alloy powder with a Sn content of 3 to 15 mass % and pure copper powder were mixed so as to have the components shown in the table, and then spread on the substrate. However, for Samples 24 and 25, Cu-12Sn-15Ni-3P alloy powder was used instead of copper-tin alloy powder. Regarding Samples 27 to 29, Sample 31, and Sample 32, predetermined amounts of graphite powder and SiC powder were also mixed. The base plate is a steel plate with a thickness of 2.2mm. The dispersed powder was subjected to first sintering, rolling, and second sintering to obtain a bearing alloy layer with a thickness of 0.9 mm. The sintering conditions for each sample are as shown in Table 2. Furthermore, the number and area ratio of high tin concentration regions (threshold 1.1 times, that is, regions with a Sn concentration of 1.1 times or more of the average Sn concentration) in the bearing alloy layer were measured by the measurement method described above. The abrasion test of each sample was performed according to the conditions shown in Table 3, and the abrasion amount of the sample after the test was measured. The results are shown in Tables 4 to 6.

【table 3】 Testing machine Ring-on-disk friction and wear testing machine Face pressure 10MPa sliding speed 2.0m/min temperature 200℃ Lubricate butter Opposite axis S55C Test time 5 hours

According to the results shown in Table 4, it can be seen that Samples 1 to 23 (Cu-Sn alloy system according to the examples of the present invention contain Sn: 1.5 to 10.0 mass %, and the number of high tin concentration regions is 1.1 times the threshold per 1 mm ² 5 to 93), compared with Samples 41 to 47 of Comparative Examples that do not have a high Sn concentration region, if the Sn concentration is the same, the amount of wear based on the wear test is reduced.

In Samples 24 and 25 according to the examples of the present invention, the Cu-Sn alloy contains 5.0 mass% Ni and 1.0 mass% P in addition to 4.0 mass% Sn. Table 5 shows the wear amount of these samples based on the wear test. Table 5 also shows the test results of Sample 13 and Sample 20. The Sn concentration, number of high concentration regions, and area ratio of Sample 13 and Sample 20 are the same as those of Sample 24 and Sample 25 respectively but do not contain Ni and P. From the results shown in Table 5, it can be seen that if the Sn concentration and the number and area ratio of the high concentration regions are the same, the amount of wear can be reduced by adding Ni and P.

Table 6 shows Samples 26 to 29, Sample 31 and Sample 32 (the bearing alloy contains graphite and SiC in addition to the Cu-Sn alloy containing 3.0 mass % Sn) and those containing no graphite and SiC. Comparison of sample 26 and sample 30. From the results shown in Table 6, it can be seen that the amount of wear based on the wear test can be reduced by containing graphite and SiC.

Table 7 shows a comparison of the wear amount between the sample of the present invention and the comparative example in which the average Sn concentration of the Cu-Sn alloy is the same (no high concentration area is formed). According to Table 7, it can be seen that the sample with the number of high concentration areas of 40/mm ² has a better improvement in wear resistance than the sample with the number of 5/mm ² . The number of any high-concentration regions is such that when the average Sn concentration is in the range of 2.0 mass% to 8.0 mass%, the improvement in wear resistance is more excellent.

1: Sliding component 2: Bearing alloy layer 3: Sliding surface 4:Back cushion layer 6: High tin concentration area 8:Matrix

[Fig. 1] shows a structural example of a sliding member according to a specific example of the present invention. [Fig. 2] A cross-sectional view perpendicular to the sliding surface of a Cu-Sn alloy of a sliding member according to a specific example of the present invention.

1: Sliding component

2: Bearing alloy layer

6: High tin concentration area

8:Matrix

Claims (11)

A sliding member, which is a sliding member with a sliding surface and includes a bearing alloy containing a Cu-Sn alloy. The aforementioned Cu-Sn alloy contains Sn: 1.5~10.0% by mass, and the remainder is Cu and impurities. From the above High tin concentration regions are dispersed in the vertical cross section of the sliding surface. The high tin concentration region has a Sn concentration that is 1.1 times or more of the average Sn concentration of the Cu-Sn alloy and has an area of 500 μm or more. The high tin concentration region has an area of 500 μm ^or more. The number is 5~93 per ^1mm2 . Such as the sliding member of claim 1, wherein, Observed from a cross section perpendicular to the sliding surface, the area ratio of the high tin concentration area is 5 to 47%. Such as the sliding member of claim 1 or 2, wherein, The Sn content of the Cu-Sn alloy is 8.0 mass% or less. Such as the sliding member of claim 1 or 2, wherein, The Sn content of the Cu-Sn alloy is 2.0% by mass or more. Such as the sliding member of claim 1 or 2, wherein, The aforementioned Cu-Sn alloy further contains either one or both of Ni: 0 to 5.0 mass% and P: 0 to 1.0 mass%. Such as the sliding member of claim 1 or 2, wherein, The aforementioned bearing alloy further contains any one or both of solid lubricant particles and hard particles. Such as the sliding member of claim 6, wherein, The solid lubricant particles are graphite particles. Such as the sliding member of claim 6, wherein, The hard particles are SiC particles. Such as the sliding member of claim 1 or 2, wherein, The sliding member includes a backing layer and a bearing alloy layer on the backing layer, and the bearing alloy layer includes the bearing alloy. Such as the sliding member of claim 9, wherein, The aforementioned sliding member is a sliding bearing. A bearing device includes a sliding member as claimed in claim 10.

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