JP2021089009A - Slide member - Google Patents

Abstract

To provide a slide member improved in abrasion resistance of a resin overlay layer without increasing a coefficient of friction even when large bearing pressure and load are applied.SOLUTION: A resin overlay layer 13 has a resin binder 20, and solid lubricant particles 21 of anisotropic shape, dispersed in the resin binder 20. A slide surface 14 of the resin overlay layer 13 is defined as 0°, a virtual axis 34 vertical to the slide surface 14 is defined as 90°, the total number of the particles 21 included in an arbitrary observation region of the resin binder 20 is defined as N, and a parameter of a distribution is defined as a. A range of 0° to 90° from the slide surface 14 to the axis 34 is divided into angular ranges of A-10°<x≤A (A=10, 20, 30,...,90) by 10°, and an angle θ of a major axis 31 of the particle 21 is classified to be included in any of the angular ranges. When the numbers n of the particles 21 included in the angular ranges are respectively counted, a distribution ratio n/N(%) of the particles 21 included in the resin binder satisfies a specific formula.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sliding member.

Conventionally, a sliding member having a resin overlay layer on the sliding surface side of the bearing alloy layer is known (Patent Document 1). A solid lubricant is added to the resin overlay layer, which contributes to reduction of friction and improvement of compatibility. Patent Document 1 aims to improve the characteristics by specifying the intensity ratio of the diffraction surface of the solid lubricant by X-ray diffraction. That is, in the case of Patent Document 1, the sliding performance is improved by setting the cleavage direction of the solid lubricant contained in the resin overlay layer.

However, in recent years, with the further increase in output and rotation of the internal combustion engine, the sliding member is exposed to a larger surface pressure and a larger load. When the surface pressure and the load are increased in this way, solid contact with the mating member is likely to occur due to the oil film running out of the lubricating oil. When solid contact occurs, there is a problem that the resin overlay layer is worn out at an early stage, resulting in seizure.

Japanese Unexamined Patent Publication No. 2008-9725

Therefore, it is an object of the present invention to provide a sliding member in which the abrasion resistance of the resin overlay layer is improved without increasing the friction coefficient even when a large surface pressure and load are applied.

In order to solve the above problems, the sliding member of the present embodiment includes a resin overlay layer on the sliding surface side of the bearing alloy layer.
The resin overlay layer has a resin binder and particles of a solid lubricant having an anisotropic shape of 20% by volume or more dispersed in the resin binder.
The virtual straight line parallel to the sliding surface is 0 °, the virtual axis perpendicular to the sliding surface is 90 °, the total number of the particles contained in an arbitrary observation region of the resin binder is N, and the distribution is Define the parameter as a and
The range of 0 ° to 90 ° from the sliding surface to the axis is set to the angle range of A-10 ° <x≤A (A = 10, 20, 30, ..., 90) in 10 ° increments. When the angle of the major axis of the particles is classified into which of the angle ranges, and the number n of the particles included in the angle range is counted, respectively.
The distribution ratio n / N (%) of the particles contained in the resin binder is a sliding member represented by the following formula (1).

As described above, the particles of the solid lubricant contained in the resin overlay layer have a distribution satisfying the formula (1) for each angle range. The particles of the solid lubricant contained in the resin overlay layer are classified into particles having a large vertical component in the thickness direction of the resin overlay layer and particles having a large horizontal component in the direction along the sliding surface depending on the posture. Lubrication. The particles having a large vertical component support the resin overlay layer in the thickness direction, which contributes to the improvement of wear resistance. On the other hand, particles having a large horizontal component have a large area when exposed to the sliding surface, which contributes to a reduction in the coefficient of friction. When the solid lubricant particles have a distribution satisfying the formula (1) as in the present embodiment, the solid lubricant particles contained in the resin overlay layer have an appropriate ratio of the vertical component and the horizontal component. As a result, the strength of the resin overlay layer is improved by the particles having a large vertical component, and the friction coefficient is reduced by the particles having a large horizontal component. Therefore, even when a larger surface pressure and load are applied, the abrasion resistance of the resin overlay layer can be improved without increasing the friction coefficient.
In this equation (1), the distribution parameter a is preferably 10 ≦ a ≦ 160 and more preferably 25 ≦ a ≦ 80.
In the equation (1), n / N [%] on the left side means a value converted as a percentage. Further, the range of 0 ° to 90 ° from the virtual straight line parallel to the sliding surface to the axis is A-10 ° <x≤A ° (A = 10, 20, 30, ... , 90). That is, the range from the straight line to the axis is 0 ° ≤ x ≤ 10 °, 10 ° <x ≤ 20 °, 20 ° <x ≤ 30 °, 30 ° <x ≤ 40 °, 40 ° <x ≤ 50 °, It is divided into 50 ° <x ≦ 60 °, 60 ° <x ≦ 70 °, 70 ° <x ≦ 80 °, and 80 ° <x ≦ 90, respectively. In this case, only when A = 10, the lower limit θ = 0 ° is included in the angle range of 0 ° to 10 °.

Schematic diagram showing particles of solid lubricant contained in the resin overlay layer of the sliding member according to one embodiment. Schematic cross-sectional view showing a sliding member according to one embodiment Schematic diagram showing an observation area set in the resin overlay layer in the sliding member according to one embodiment. Schematic diagram for explaining a method of manufacturing a sliding member according to an embodiment. Schematic diagram showing test conditions in Examples and Comparative Examples of Sliding Members According to One Embodiment Schematic diagram showing the test results of Examples and Comparative Examples of Sliding Members According to One Embodiment Schematic diagram showing the test result of the example of the sliding member according to one Embodiment

Hereinafter, an embodiment of the sliding member will be described with reference to the drawings.
As shown in FIG. 2, the sliding member 10 includes a back metal layer 11, a bearing alloy layer 12, and a resin overlay layer 13. The sliding member 10 may include an intermediate layer (not shown) between the back metal layer 11 and the bearing alloy layer 12. Further, the sliding member 10 is not limited to the example shown in FIG. 2, and includes a plurality of bearing alloy layers 12, intermediate layers, and other layers having other functions between the back metal layer 11 and the resin overlay layer 13. May be good. The sliding member 10 forms a sliding surface 14 that slides with the mating member at the end on the resin overlay layer 13 side. In the case of the present embodiment shown in FIG. 2, in the sliding member 10, the bearing alloy layer 12 and the resin overlay layer 13 are sequentially laminated on the sliding surface 14 side of the back metal layer 11. The back metal layer 11 is formed of a metal or alloy such as iron or steel. The bearing alloy layer 12 is formed of, for example, Al or Cu, or an alloy thereof.

As shown in FIG. 3, the resin overlay layer 13 includes a resin binder 20 and particles 21 of a solid lubricant. The resin binder 20 is a main component constituting the resin overlay layer 13, and includes, for example, polyamideimide, polyimide, polybenzoimidazole, polyamide, epoxy resin, phenol resin, polyacetal, polyetheretherketone, polyethylene, polyphenylene sulfide, and polyetherimide. , One or more selected from fluororesin and elastomer resin are used. Further, the resin binder 20 may be a polymer alloy. In this embodiment, polyamide-imide is used as the resin binder 20. Further, the solid lubricant is selected from those having a cleavable or layered structure, such as molybdenum disulfide, tungsten disulfide, h-BN, graphite fluoride, graphite, mica, talc, and melamine cyanurate. More than one is used. Further, the solid lubricant particles 21 preferably have high load bearing capacity. In the case of this embodiment, molybdenum disulfide having high load resistance is used as the solid lubricant.

Additives such as a filler may be added to the resin overlay layer 13. In this case, the additives are calcium fluoride, calcium carbonate, calcium phosphate, iron oxide, aluminum oxide, chromium oxide, cerium oxide, zirconium oxide, titanium oxide, silicon oxide, oxides such as magnesium oxide, molybdenum carbide, silicon carbide and the like. One or more selected from carbides, aluminum nitride, silicon nitride, cubic boron nitride, diamond and the like are used.

In the sliding member 10 of the present embodiment, the resin overlay layer 13 contains 20% by volume or more of the solid lubricant particles 21. In this case, the resin overlay layer 13 preferably has an upper limit of the content of the solid lubricant of about 60% by volume. This is because if the content of the solid lubricant exceeds 60% by volume, the physical strength of the resin overlay layer 13 may decrease due to the lack of the resin binder 20. However, the upper limit of the content of the solid lubricant can be adjusted by the combination of the resin binder 20 constituting the resin overlay layer 13 and the solid lubricant.

In the case of the present embodiment, the solid lubricant particles 21 have an anisotropic shape having a major axis 31 and a minor axis 32 as shown in FIG. The particles 21 of the solid lubricant are dispersed in the resin binder 20. The solid lubricant particles 21 contained in the resin overlay layer 13 form a virtual shaft 34 extending in the thickness direction perpendicular to the sliding surface 14 at 0 ° along a virtual straight line 33 parallel to the sliding surface 14. Is defined as 90 °, the major axis 31 is tilted as an angle θ in the range of 0 ° to 90 °. Specifically, as shown in FIG. 3, the resin overlay layer 13 is cut in an arbitrary cross section in the thickness direction, and an arbitrary observation region S is set in this cross section. The total number of particles 21 included in the observation region S is defined as the total number N. In the present embodiment, the particles 21 that straddle the boundary line that divides the observation area S are not measured. Further, as shown in FIG. 1, the major axis 31 of each particle 21 is extracted from the particles 21 included in the observation region S. In this case, in the observation area S, for example, an image observed by a scanning electron microscope (SEM) is analyzed by analysis software. In this embodiment, "Image-pro plus ver.4.5" is used as the analysis software. Specifically, the solid lubricant particles 21 included in the obtained image are approximated to an ellipse, and the angle θ of the major axis 31 of the particles 21 is detected from the approximated ellipse. The approximation to an ellipse is performed, for example, by calculating an ellipse having the same area, the same primary moment, and the same secondary moment as the target particle 21. In the present embodiment, among the particles 21 included in the observation region S, those having a major axis 31 of 0.3 μm or more are targeted for observation. As a matter of course, when two angles θ of the long axis are measured between the straight line 33 and the axis 34, the smaller one is adopted.

As shown in FIG. 1, when the straight line 33 parallel to the sliding surface 14 is 0 ° and the virtual axis 34 perpendicular to the straight line 33 is 90 °, the distance from the straight line 33 to the axis 34 is 0 ° to 90 °. The range is divided into an angular range of A-10 ° <x≤A (A = 10, 20, 30, ..., 90) in 10 ° increments. That is, the range from the straight line 33 to the axis 34 is 0 ° ≦ x ≦ 10 °, 10 ° <x ≦ 20 °, 20 ° <x ≦ 30 °, 30 ° <x ≦ 40 °, 40 ° <x ≦ 50. It is divided into °, 50 ° <x ≦ 60 °, 60 ° <x ≦ 70 °, 70 ° <x ≦ 80 °, and 80 ° <x ≦ 90, respectively. In this case, only when A = 10, the lower limit θ = 0 ° is included in the angle range of 0 ° to 10 °. The angle θ of the major axis 31 of the particles 21 included in the observation region S is classified as which of the 10 ° angle ranges belongs to. Then, the number of particles 21 whose major axis 31 is in the angle range is counted for each of the divided 10 ° angle ranges, and the number is set to n. In the case of this embodiment, the distribution ratio n / N (%) of the particles 21 included in the observation region S is the distribution represented by the following formula (1). In equation (1), e is the natural logarithm and a is the parameter of the distribution. In the case of the present embodiment, the distribution parameter a is preferably 10 ≦ a ≦ 160, and more preferably 25 ≦ a ≦ 80. In the equation (1), n / N [%] on the left side means a value converted as a percentage.

Next, a method of manufacturing the sliding member 10 according to the present embodiment will be described.
As shown in FIG. 4, the bimetal 40 having the bearing alloy layer 12 formed on one surface side of the back metal layer 11 is formed into a cylindrical shape. In this case, the bimetal 40 may form the bearing alloy layer 12 on the inner peripheral side after forming the back metal layer 11 into a cylindrical shape. Further, the bimetal 40 is not limited to a cylindrical shape, and may be a semi-cylindrical shape or a shape obtained by dividing the cylinder into a plurality of parts in the circumferential direction. In the bimetal 40, the spray portion 41 and the heat source 42 are arranged at positions facing the bearing alloy layer 12 on the inner peripheral side. The spray unit 41 has a nozzle 43. The nozzle 43 injects a resin binder 20 containing particles 21 of a solid lubricant for forming the resin overlay layer 13. Further, the heat source 42 heats the inner peripheral side of the bimetal 40 in order to dry the injected resin binder 20.

In the case of the present embodiment, the bimetal 40 formed in a cylindrical shape is rotated in the circumferential direction as shown by the arrow in FIG. As a result, the nozzle 43 of the spray unit 41 injects the resin binder 20 containing the solid lubricant particles 21 toward the inner peripheral side of the rotating bimetal 40. The resin binder 20 adhering to the inner peripheral side of the bimetal 40 is heated by the heat source 42 and dried.

When the resin binder 20 containing the solid lubricant particles 21 is simply sprayed from the nozzle 43 of the spray unit 41 onto the inner peripheral side of the bimetal 40, the solid lubricant particles 21 contained in the resin binder 20 have an irregular posture. .. That is, the solid lubricant particles 21 are included in the resin binder 20 in an irregular posture in which the distribution of the angle θ is random without controlling the posture. On the other hand, in the present embodiment, when the resin overlay layer 13 is formed, the bimetal 40 is rotated at a high speed while the resin binder 20 is sprayed and dried. As a result, the surface of the resin binder 20 is solidified on the surface, that is, the side close to the nozzle 43, prior to the inside of the sprayed layer. Therefore, the surface of the resin binder 20 adhering to the bimetal 40 is solidified and the inside becomes semi-dry. As a result, the solid lubricant particles 21 contained in the resin binder 20 are captured by the resin binder 20 whose side near the surface of the long axis 31 is solidified prior to other portions, and the change in posture is restricted. On the other hand, the posture of the solid lubricant particles 21 can be changed inside the semi-dry resin binder 20 until the inside of the resin binder 20 is solidified. Therefore, the angle θ of the solid lubricant particles 21 with respect to the sliding surface 14 changes inside the semi-dry resin binder 20 due to the centrifugal force applied by the rotation of the bimetal 40. Then, when the resin binder 20 is completely dried to the inside, the posture of the solid lubricant particles 21 is fixed.

As described above, in the present embodiment, for example, the rotation speed of the bimetal 40, the temperature of the heat source 42, the distance from the heat source 42 to the resin binder 20 and the like are adjusted to obtain the solid lubricant contained in the resin binder 20. The angle θ of the particle 21 is controlled. The rotation speed of the bimetal 40 may be constant from the initial stage to the final stage of forming the resin overlay layer 13, and may be accelerated or decelerated during the formation.

As described above, when the resin binder 20 containing the solid lubricant particles 21 is injected onto the bimetal 40 and the solidified resin binder 20 is formed to a desired thickness, the sliding member 10 having the resin overlay layer 13 is formed. Will be done.

Hereinafter, an embodiment of the sliding member 10 according to the present embodiment will be described in comparison with a comparative example.
For the samples of Examples and Comparative Examples of the sliding member 10 manufactured by the above procedure, the wear resistance was evaluated from the amount of wear using the conditions shown in FIG. 5, and the friction coefficient was measured. Under the test conditions shown in FIG. 5, the rotation speed is not constant at 500 rpm, and is a "start-stop" test in which 0 rpm and 500 rpm are repeated every 5 seconds.

As shown in FIG. 6, it is clear that Example 1 satisfying the distribution of the formula (1) has improved wear resistance as compared with Comparative Example not satisfying the distribution of the formula (1). As described above, when the distribution of the formula (1) is satisfied, the solid lubricant particles 21 contained in the resin overlay layer 13 not only contribute to the reduction of the friction coefficient as its original action, but also the resin. It is considered that this is because it contributes to the improvement of the strength of the overlay layer 13. That is, the solid lubricant particles 21 contained in the resin overlay layer 13 act as columns that support the resin overlay layer 13 in the thickness direction due to the increase in the vertical component. On the other hand, the solid lubricant particles 21 contained in the resin overlay layer 13 have a large horizontal component, so that the area exposed on the sliding surface 14 is expanded, which contributes to the reduction of the friction coefficient. When the distribution of the formula (1) is satisfied as in Example 1, the vertical component and the horizontal component of the solid lubricant particles 21 contained in the resin overlay layer 13 are appropriate. Therefore, the particles 21 of the solid lubricant contribute not only to the reduction of the friction coefficient, which is the original action, but also to the improvement of the strength of the resin overlay layer 13. As a result, even when the surface pressure is as large as 10 MPa as in the condition shown in FIG. 5, the wear resistance of the resin overlay layer 13 is enhanced while maintaining the coefficient of friction.

FIG. 7 verifies the distribution parameter a of the equation (1). The amount of wear of the resin overlay layer 13 tends to decrease as the parameter a increases. On the other hand, the friction coefficient of the resin overlay layer 13 tends to increase as the parameter a increases. From this, it can be seen that when the parameter a is in a predetermined range, the resin overlay layer 13 has improved wear resistance without increasing the friction coefficient. With reference to Examples 2 to 11 shown in FIG. 7, when the parameter a is 10 ≦ a ≦ 160, the resin overlay layer 13 does not cause an increase in the coefficient of friction, and the wear resistance is remarkably improved. In particular, it can be seen that in Examples 5 and 6 in which the parameter a is 25 ≦ a ≦ 80, the wear resistance is remarkably improved without causing an increase in the friction coefficient.

The present invention described above is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

In the drawings, 10 is a sliding member, 12 is a bearing alloy layer, 13 is a resin overlay layer, 14 is a sliding surface, 20 is a resin binder, and 21 is a particle 1.

Claims (3)

A sliding member provided with a resin overlay layer on the sliding surface side of the bearing alloy layer.
The resin overlay layer is
With a resin binder,
It has 20% by volume or more anisotropically shaped solid lubricant particles dispersed in the resin binder.
The virtual straight line parallel to the sliding surface is 0 °, the virtual axis perpendicular to the sliding surface is 90 °, the total number of the particles contained in an arbitrary observation region of the resin binder is N, and the distribution is Define the parameter as a and
The range of 0 ° to 90 ° from the sliding surface to the axis is set to the angle range of A-10 ° <x≤A (A = 10, 20, 30, ..., 90) in 10 ° increments. When the angle of the major axis of the particles is classified into which of the angle ranges, and the number n of the particles included in the angle range is counted, respectively.
The distribution ratio n / N (%) of the particles contained in the resin binder is a sliding member represented by the following formula (1).

The sliding member according to claim 1, wherein the parameter a of the distribution is 10 ≦ a ≦ 160. The sliding member according to claim 2, wherein the parameter a of the distribution is 25 ≦ a ≦ 80.

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