Sliding element

Abstract

Sliding element (1), comprising: a back sheet (10) made of steel as the outermost layer of the sliding element (1), a sintered lining (11) consisting of Cu, Bi and Sn, and an electroplated cover layer (12) as a sliding surface, which is formed from an alloy deposition film of Bi and Sb, wherein the cover layer (12) consists of Bi, Sb and unavoidable impurities, and wherein the Sb concentration on the surface of the cover layer (12) is 0.92 wt% or more and 2.1 wt% or less, wherein the cover layer (12) has a concentration gradient, wherein the Sb concentration increases as the depth or distance from the surface of the cover layer (12) increases.

Description

TECHNICAL AREA

[0001] The present invention relates to a sliding element with a cover layer made of an alloy deposition film of Bi and Sb. STATE OF THE ART

[0002] A sliding element is known with a top layer comprising a coating of bismuth (Bi) and an intermediate layer of silver (Ag) (see patent specification 1). Patent specification 1 describes an improvement in the adhesion of the top layer by adjusting the size of the silver crystal grains in the intermediate layer. Furthermore, adjusting the size of the bismuth crystal grains in the coating improves the adhesion and fatigue resistance of the top layer film. LIST OF COUNTER-POINTS PATENT PUBLICATIONS

[0003] Patent specification 1: JP 2006-266445 A SUMMARY OF INVENTIONAL PROBLEMS

[0004] However, even if layer adhesion is improved by adjusting the crystal grain size as described in patent specification 1, the problem remains that layer detachment is unavoidable because the top layer has a two-layer structure. Furthermore, if the top layer has a two-layer structure, sudden changes in the coating properties during wear are also unavoidable.

[0005] The present invention was made in view of the above problems, and it is an object of the present invention to provide a sliding element with a cover layer that can achieve good fatigue resistance while avoiding separation of the layers. SOLUTIONS TO THE PROBLEMS

[0006] To achieve the aforementioned objective, the sliding element of the present invention is a sliding element with a cover layer consisting of an alloy deposition film of Bi and Sb. The cover layer contains Bi, Sb, and unavoidable impurities. The Sb concentration on the surface of the cover layer is 0.92 wt% or more and 13 wt% or less.

[0007] Since the topcoat in the aforementioned configuration contains not only soft bi but also hard saber, the hard saber can improve fatigue resistance. The saber may or may not exhibit a concentration gradient within the topcoat. In any case, good fatigue resistance can be confirmed when the saber concentration on the surface of the topcoat is 0.92 wt% or higher. It can also be confirmed that no cracking occurs on the surface of the topcoat, even when the saber concentration on the surface of the topcoat is increased to 13 wt%. List of characters Fig. Figure 1 is a perspective view of a sliding element according to an embodiment of the present invention. Fig. Figure 2 is a diagram of the Sb concentration in a cover layer; Fig. 3 is a photo of the cross-section of the top layer; Fig. Figure 4 is an explanatory diagram of a fatigue test. Fig. Figure 5 is a curve diagram and shows the relationship between the Sb concentration and the proportion of the fatigue area. DESCRIPTION OF THE EXECUTION FORMS

[0008] The embodiments according to the invention are described in the following order. (1) First embodiment: (1-1) Structure of the sliding element: (1-2) Manufacturing process for the sliding element: (2) Sb concentration: (3) Other embodiments: First embodiment: Structure of the sliding element:

[0009] Fig. Figure 1 is a perspective view of a sliding element according to an embodiment of the present invention. The sliding element 1 has a rear panel 10 , a lining 11 and a top layer 12 on. The sliding element 1 is a semi-tubular metal component obtained by dividing a hollow cylinder diametrically into two equal parts, and has a cross-section in the shape of a semicircular arc. By connecting the two sliding elements 1 A sliding bearing is formed into a cylindrical shape. A trained. The plain bearing A carries a cylindrical countershaft 2 (Crankshaft of an engine) in a hollow section formed therein. The outer diameter of the countershaft 2 is slightly smaller than the inner diameter of the plain bearing Aformed. A lubricating oil (engine oil) is introduced into a space between the outer circumferential surface of the counter shaft. 2 and the inner circumferential surface of the sliding bearing A is formed. Now the outer circumferential surface of the counter shaft slides. 2 on the inner circumferential surface of the sliding bearing A .

[0010] The sliding element 1 has a structure, with the back panel being... 10 , the lining 11 and the top layer 12 They are laminated in such a way that they are spaced away from the center of curvature. Therefore, the back sheet forms 10 the outermost layer of the sliding element 1 , and the top layer 12 forms the innermost layer of the sliding element 1 The rear panel 10 , the lining 11 and the top layer 12 They each have a constant thickness in the circumferential direction. The thickness of the back panel sheet. 10The lining thickness is 1.8 mm. 11 is 0.2 mm, and the thickness of the top layer 12 is 20 µm. This is twice the radius of the surface on the side of the center of curvature of the top layer. 12 (Inner diameter of the sliding element) 1 ) is 55 mm. The width of the plain bearing A is 19 mm. In the following, the term "inside" means the side of the center of curvature of the sliding body. 1 , and the term "outside" means the side opposite the center of curvature of the sliding body. 1 The inner surface of the top layer 12 forms the sliding surface for the counter shaft 2 .

[0011] The rear panel 10 consists of steel, which contains 0.15% by mass. C , 0.06 wt% Mn, and the remaining amount contains Fe. It is sufficient that the back panel sheet 10 consists of a material that transfers the load from the countershaft 2 about the lining 11and the top layer 12 can carry, and the back panel 10 It doesn't necessarily have to be made of steel.

[0012] The lining 11 is one on the inside of the rear panel 10 laminated layer and forms the base layer of the present invention. The lining 11 Contains 10 wt% Sn, 8 wt% Bi, and the remainder consists of Cu and unavoidable impurities. The unavoidable impurities of the lining 11 These include Mg, Ti, B, Pb, Cr, and similar impurities introduced during refining or scrapping. The content of unavoidable impurities in the lining 11 The total mass percentage is 0.5% or less.

[0013] The top layer 12 is a feature on the inner surface of the lining 11 laminated layer. The top layer 12is an alloy deposition film of Bi and Sb. Furthermore, the top layer contains 12 Bi, Sb and unavoidable impurities. The content of unavoidable impurities in the surface layer. 12 The total mass percentage is 0.5% or less. [Table 1] Distance [µm] from interface First area Second area Average overall concentration First area / Second area 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Sb concentration of sample A Concentration [mass %] 13,12 9,30 4,19 2,39 2,53 2,14 2,56 1,99 2,31 2,18 1,94 2,67 1,98 2,18 2,12 2,14 1,76 2,05 2,36 1,73 3,05 - Inclination [mass % / µm] 3,82 5,11 1,80 0,14 0,39 0,42 0,57 0,32 0,13 0,24 0,73 0,69 0,20 0,06 0,02 0,38 0,29 0,31 0,63 - - - average inclination [mass % / µm] 2,72 0,36 - 7,6 Standard deviation [mass %] 4,89 0,27 - 18,1 Sb concentration of sample B Concentration [mass %] 4,37 2,78 1,57 1,66 0,90 1,42 0,96 0,83 0,94 1,07 1,11 1,11 1,05 1,26 0,53 0,63 0,95 0,55 0,76 1,08 1,31 - Inclination [mass % / µm] 1,59 1,21 0,09 0,76 0,52 0,46 0,13 0,11 0,13 0,04 0,00 0,06 0,21 0,73 0,10 0,32 0,40 0,21 0,32 - - - average inclination [mass % / µm] 0,91 0,25 - 3,7 Standard deviation [mass %] 1,31 0,25 - 3,2 Sb concentration of sample C Concentration [mass %] 1,83 0,92 1,34 1,62 0,38 1,22 1,71 1,78 2,28 2,44 2,26 2,72 1,42 1,69 2,90 1,88 2,39 3,26 - - 1,89 - Inclination [mass % / µm] 0,91 0,42 0,28 1,24 0,84 0,49 0,07 0,50 0,16 0,18 0,46 1,30 0,27 1,21 1,02 0,51 0,87 - - - - - average inclination [mass % / µm] 0,71 0,61 - - - 1,2 Standard deviation [mass %] 0,39 0,98 - - - 0,4

[0014] Table 1 shows the Sb concentration (mass concentration) in the top layer. 12 to. Fig. Figure 2 is a diagram and shows the Sb concentration (mass concentration) in the top layer. 12 The horizontal axis in Fig. 2 gives the distance from the interface between the top layer 12 and the lining 11 The vertical axis indicates the Sb concentration. Table 1 and Fig.Figure 2 shows the Sb concentration in sample A (triangles), which approaches approximately 2 mass-%, the Sb concentration in sample B (circles), which approaches approximately 1 mass-%, and the concentration in sample C (Quadrates) where no concentration gradient is specified. As in Fig. As shown in Figure 2, the Sb concentration increases at the interface between the top layer in samples A and B. 12 and the lining 11 to its maximum. In samples A and B, the Sb concentration increases with increasing distance from the interface between the top layer and the lining. 11 continuously (with decreasing depth or with decreasing distance from the surface of the top layer) 12 The average Sb concentration in the entire top layer 12 It was 3.05% by mass.

[0015] In samples A and B, the slope (absolute value) of the Sb concentration decreases, while the distance from the interface between the top layer 12and the lining 11 increases, and the Sb concentration approaches a nearly constant level in a range where the distance from the interface between the top layer 12 and the lining 11 4 µm or more. In samples A and B, the slope and standard deviation of the Sb concentration are measured in a first region where the depth from the surface of the cover layer is... 12 a first depth is (area where the distance from the interface X between the top layer 12 and the lining 11 4 µm or less), greater than the slope and standard deviation of the Sb concentration in a second area where the depth from the surface of the cover layer is shallower than the first depth (area where the distance from the interface X between the cover layer 12 and the lining 11 larger than 4 µm).

[0016] The slope of the Sb concentration in the first region of sample A is 7.6 times the slope of the Sb concentration in the second region. The standard deviation of the Sb concentration in the first region of sample A is 18.1 times the standard deviation of the Sb concentration in the second region. Conversely, the slope of the Sb concentration in the first region of sample B is 3.7 times the slope of the Sb concentration in the second region. The standard deviation of the Sb concentration in the first region of sample B is 3.2 times the standard deviation of the Sb concentration in the second region.

[0017] The top layer 12 The present embodiment is formed using the same manufacturing process as in sample A, and the Sb concentration on the surface of the cover layer 12With a film thickness of 20 µm, the Sb concentration was 1.8 wt%. Therefore, it can be concluded that in the present embodiment, a similar Sb concentration gradient exists as in sample A. Fig. 2 is present. The Sb concentration in the top layer 12 is achieved by lowering or reducing the Sb concentration in the electrolyte of the surface layer 12 Adjustable, as described below.

[0018] Fig. Figure 3 is a photo of the cross-section of the top layer 12 ; In the photo of the cross-section in Fig. 3. Imaging is performed at a location with a higher Sb concentration, which is represented in a darker color. As in Fig. As shown in Figure 3, the Sb concentration decreases continuously as the depth increases from the surface of the cover layer. 12 decreases. That is, when the depth decreases from the surface of the top layer. 12As the depth increases, the Sb concentration rises continuously. Furthermore, since the remainder of the Sb can be assumed to be Bi, the Bi concentration decreases continuously with increasing depth from the surface of the caprock. 12 increases. That is, when the depth from the surface of the top layer increases. 12 As the amount decreases, the bi concentration rises continuously. It should be noted that Fig. 3. A diagram of the cross-section of the top layer 12 with a thickness of approximately 10 µm.

[0019] The Sb concentration in the top layer 12 was measured by energy-dispersive X-ray spectroscopy using an electron beam microanalyser (JMS-6610A, manufactured by JEOL Ltd.). In particular, a multitude of rectangular regions E were formed, where the distance from the interface X between the cover layer 12 and the lining 11The distance to the upper end (end on the surface side) differs by 1 µm, and the average Sb mass concentration in the rectangular areas E was measured as the Sb mass concentration at the respective distance. A total area EA, consisting of all rectangular areas E, was formed, and the average Sb mass concentration in the total area EA was measured as the average Sb concentration in the entire cover layer.

[0020] A fatigue test specimen (connecting rod) R ) with a top layer 12 similar to the sliding element described above 1 It was prepared to measure its proportion of the fatigue area. A fatigue area proportion of 30% was found, which was good. The fatigue area proportion was measured using the following procedure. Fig. Figure 4 is an explanatory diagram of a fatigue test. First, as in Fig.4 shown, a connecting rod R prepared with cylindrical through holes formed longitudinally at both ends, and a test shaft H (hatched) was stored at one end in the through-hole.

[0021] A top layer 12 (black) similar to the one on the sliding element 1 was formed on the inner circumferential surface of the through hole to accommodate the connecting rod R trained test shaft H to store. The test shaft H was applied to both outer sides of the connecting rod R in the axial direction of the test shaft H stored, and the test shaft H It was rotated so that the sliding speed reached 6.6 m / s. The sliding speed is the relative speed between the surface of the top layer. 12 and the test wave H The end section of the connecting rod R on the side opposite the test shaftH was with a moving body F connected, which extends in the longitudinal direction of the connecting rod R moved back and forth, and the alternating load of the moving body F was set to 80 MPa. Also, between the connecting rod... R and the test wave H Engine oil supplied at approximately 140°C.

[0022] By continuing the aforementioned state 50 The fatigue test of the top layer lasted for hours. 12 The fatigue test was carried out. After the fatigue test, the inner surface (sliding surface) of the top layer was examined. 12 The image was photographed from a position on a straight line perpendicular to the surface, so that the straight line served as the principal optical axis. The captured image was used as the evaluation image. Then, the defective section in the surface of the top layer reflected in the evaluation image was identified. 12The area was viewed and marked using binoculars (magnifying glass). The percentage value obtained by subdividing the area of ​​the defective section, i.e., the area of ​​the defective section, is divided by the area of ​​the entire surface of the top layer reflected in the evaluation image. 12 was measured as a proportion of the fatigue area.

[0023] Since in the embodiment described above the top layer 12Since it contains not only soft bi but also hard sulfur (Sb), the hard sb can improve fatigue resistance. Furthermore, as the sb concentration increases with depth from the surface, good concordance can be achieved in the initial stages of wear, and high wear resistance can be achieved in advanced stages. Because the sb concentration also increases with depth from the surface, separation of the intermediate layers can be prevented. Here, copper exhibits the property of diffusing more readily into sb than into bi. However, the average sb concentration is determined by the entire surface layer. 12 set to less than 3.1% by mass, thereby reducing the amount of Cu that is removed from the lining. 11 into the top layer 12 diffusing into it can be reduced and prevented from reducing fatigue resistance.

[0024] The slope of the Sb concentration in a first area (area where the distance to the interface X between the top layer and the lining) 11 4 µm or less), where the depth is measured from the surface of the top layer 12 a first depth is greater than the slope of the Sb concentration in a second area (area where the distance to the interface X between the top layer and the lining is 11 (greater than 4 µm), where the depth from the surface of the top layer is less than the first depth. This allows the hardness of the top layer to be determined. 12 increase rapidly with progressive wear and tear. Manufacturing process for the sliding element:

[0025] First, a flat plate of low-carbon steel with the same thickness as the back panel was used. 10 prepared.

[0026] Then a material in powder form was used to line the body. 11formed, sprinkled onto the flat plate made of low-carbon steel. In particular, copper powder, bi-powder, and tin powder were sprinkled onto the flat plate made of low-carbon steel, so that in the lining described above... 11 The mass ratio of the respective components was obtained. It is sufficient that the mass ratio of the respective components was maintained during the lining process. 11 This is achieved, and the alloy, in powder form such as Cu-Bi or Cu-Sn, can be sprinkled onto the flat plate made of low-carbon steel. The particle size of the powders was adjusted to 150 µm or less using a test sieve (JIS Z 8801).

[0027] The flat plate made of low-carbon steel and the powders sprayed onto it were then sintered. The sintering temperature was controlled to 700–1000°C, and the sintering was carried out in an inert atmosphere. After sintering, the sintered flat plate was cooled. The lining11 It does not necessarily have to be formed by sintering and can be formed by casting or similar processes.

[0028] After cooling, a copper alloy has formed on the flat plate made of low-carbon steel. The copper alloy layer contains soft bi-particles that precipitate during cooling.

[0029] Next, the low-carbon steel with the copper alloy layer formed on it was pressed into the shape of a hollow cylinder, divided into two equal parts along its midpoint. The pressing process was then carried out so that the outer diameter of the low-carbon steel matched the outer diameter of the sliding element. 1 was adapted.

[0030] Then the surface of the rear panel was 10The formed copper alloy layer was trimmed. The cutting was then controlled so that the thickness of the layer on the back panel was reduced. 10 the formed copper alloy layer is the same as that of the lining 11 was. Thus, the lining can 11 The surface of the lining is formed after the cutting process by the copper alloy layer. The cutting process was carried out by a lathe onto which a cutting tool material, for example, sintered diamond, was placed. 11 After the cutting process, the interface between the lining 11 and the top layer 12 dar.

[0031] Then, Bi was applied to the surface of the lining in a thickness of 10 µm by electroplating. 11 laminated, which makes the top layer 12 was trained. The electroplating was carried out as follows. First, the surface of the lining was 11Washed with water. Furthermore, unnecessary oxides were removed by pickling the surface of the lining. 11 from the surface of the lining 11 removed. Then the surface of the lining was cleaned. 11 washed again with water.

[0032] After completion of the aforementioned pretreatment, electroplating was carried out by applying a current to the lining immersed in an electrolyte bath. 11 The electrolyte bath consisted of methanesulfonic acid (150 g / L), dimethanesulfonic acid (20 g / L), and an organic surfactant (25 g / L). 0.18 g / L of pure Sb was dissolved in the electrolyte by electrolysis. The electrolyte bath temperature was set to 30°C. Furthermore, the lining was... 11 The applied current was a direct current, and the current density was set to 2.0 A / dm². 2 set.

[0033] The electrolyte concentration of methanesulfonic acid can be adjusted from 50 to 250 g / L, and the concentration of dimethanesulfonic acid from 5 to 40 g / L. The concentration of Sb is 0.1 to 3 g / L. The concentration of the organic surfactant is adjustable between 0.5 and 50 g / L. The electrolyte temperature can be set from 20°C to 50°C, and the current density applied to the lining can be adjusted. 11 The applied current can range from 0.5 to 7.5 A / dm² 2 The Sb concentration in the top layer will be adjusted. 12 can be increased by increasing the Sb ion concentration in the electrolyte.

[0034] For example, by adjusting the Sb concentration in the electrolyte to 0.2 g / L, an Sb concentration (triangles) was obtained which in Fig. 2 was approximately 2 mass-%. By adjusting the Sb concentration in the electrolyte to 0.1 g / L, an Sb concentration (circles) was obtained which in Fig.2 was approximately 1 mass-%. Furthermore, it was shown that the Sb concentration gradient can be achieved by using methanesulfonic acid in the electrolyte. If the cover layer 12 A coating layer was formed in an electrolyte using EDTA (ethylenediaminetetraacetic acid) instead of methanesulfonic acid. 12 formed without a concentration gradient, as in sample C of the Fig. 2.

[0035] After electroplating as described above, the surface was washed with water and dried. Thus, the sliding element was... 1 completed. Furthermore, the plain bearing was A formed by the two sliding elements 1 assembled into a cylindrical shape and attached to the engine. Sb concentration:

[0036] Table 2 shows the results of measuring the fatigue area fractions of a large number of samples. 1 until 8on, whereby the film thickness of the top layer 12 and the Sb concentration on the surface was changed. It should be noted that the first embodiment of the sample 7 corresponds. Fig. Figure 5 is a diagram of the proportions of the fatigue area of ​​the samples. 1 until 8 The vertical axis in Fig. Figure 5 indicates the proportion of the fatigue area, and the horizontal axis indicates the Sb concentration on the surface. [Table 2] Sample No. Top layer thickness [µm] Sb concentration [mass %] on surface Percentage of fatigue area [%] 1 11 0 9,9 2 11 1,7 0,2 3 11 2,6 0,8 4 14 0 31,5 5 14 1,8 2,4 6 20 0 41,1 7 (first embodiment) 20 1,8 29,6 8 20 2,4 21,8

[0037] If the top layer 12 With a greater film thickness, the proportion of fatigue area initially increases. This is assumed to be because the surface area on the inside of the top layer is affected. 12 The effective tension increases when the film thickness of the top layer increases. 12 increases, regardless of the Sb concentration. However, it was confirmed that the proportion of fatigue area at any film thickness increases when Sb is incorporated into the surface layer.12 can be reduced. Therefore, the sliding element 1 They can also be formed with favorable fatigue resistance even if the film thickness of the top layer is 12 as in the embodiment described above, the thickness is 20 µm. Furthermore, if the proportions of the fatigue areas are compared at the same film thickness, the proportion of the fatigue area can be reduced more significantly because the Sb concentration on the surface is higher.

[0038] When performing the fatigue test with specimen B of the Fig. 2 and Table 1 showed the proportion of the fatigue area. 31 0.6%, which was good. The wear progression in this wear test was 11 µm. The wear progression is the thickness of the surface layer reduced during the wear test. 12When examining the Sb concentration in the worn section (bold in Table 1) of Sample B in Table 1, the minimum value was 0.53 wt% and the maximum value was 1.26 wt%. The average concentration on the surface at the time of wear was 0.92 wt%. Furthermore, the wear of Sample B, with its strong Sb concentration gradient, did not progress to the first area. The average Sb concentration on the surface at the time of wear was measured using the same procedure as for the average Sb concentration in the entire cover layer. That is, the wear area, formed by the rectangular areas E present in the worn area, was defined to measure the average Sb mass concentration in the wear area.The average Sb concentration in the worn area is the average Sb concentration on the surface at the time of wear, because the worn area gradually becomes the surface as wear progresses.

[0039] The aforementioned facts confirmed that despite improved wear resistance with an increase in Sb concentration on the surface of the top layer, 12 Sufficient wear resistance was demonstrated even at 0.92 wt%. Furthermore, the presence of an Sb concentration gradient in the top layer is confirmed. 12 not significant. It was confirmed that even without an Sb concentration gradient, sufficient wear resistance is achieved by adjusting the Sb concentration on the surface to 0.92 wt% or more.

[0040] Furthermore, the presence of an Sb concentration gradient in the cover layer 12not significantly. Therefore, it can be said that even in the top layer 12 Sufficient wear resistance is shown without a concentration gradient, with the Sb concentration increasing with increasing depth from the surface, as in sample C in Fig. 2 and Table 1. The top layer 12 is designed without a concentration gradient like sample C, which ensures the Sb concentration on the surface while reducing the Sb concentration across the entire thickness. Other versions:

[0041] In the above embodiment, the sliding elements 1 described which the plain bearing A for bearing the crankshaft of an engine, however, the sliding elements according to the invention can be used 1 also a plain bearing Abe designed for a different purpose. For example, a radial bearing such as a gearbox bushing or a piston bushing / piston eye can be modified by the sliding element according to the invention. 1 be designed. Furthermore, the sliding element according to the invention can be used in thrust bearings, various discs or swash plates for compressors for automotive air conditioning systems. Furthermore, the matrix of the lining 11 not limited to the Cu alloy, and it is sufficient to select the matrix material according to the hardness of the counter shaft. 2 to choose. The back panel is also... 10 not essential and does not need to be used. Reference symbol list 1 sliding element 2 Counter wave 10 Rear panel 11 Lining 12 Top layer A warehouse E rectangular area F moving body H test shaft R connecting rod X interface QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2006266445 A

[0003]

Claims

[1] Sliding element comprising: a top layer formed from an alloy deposition film of Bi and Sb, the top layer contains Bi, Sb and unavoidable impurities, and where the Sb concentration on the surface of the top layer is 0.92 wt% or more and 13 wt% or less. [2] Sliding element according to claim 1, wherein the cover layer has a concentration gradient, wherein the Sb concentration increases as the depth or distance from the surface increases. [3] Sliding element according to claim 1, wherein the cover layer has no concentration gradient, wherein the Sb concentration increases as the depth of the distance from the surface increases.