JP3008222B2 - Sliding member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a sliding member, in particular, a sliding member having a surface layer provided on a lining layer via a metal barrier layer.

[0002]

2. Description of the Related Art Conventionally, as this kind of sliding member, for example, C
2. Description of the Related Art There is known a plain bearing composed of a lining layer made of a u alloy, a barrier layer made of Ni formed on the lining layer, and a surface layer made of a Pb-Sn alloy formed on the barrier layer. I have. The barrier layer is used to avoid such a problem that Sn in the surface layer diffuses and penetrates into the lining layer to embrittle the lining layer.

[0003]

The barrier layer is generally formed by an electroplating method. However, since the constituent metal Ni has an indeterminate crystal shape, the barrier layer is composed of granular crystals. The bonding surface between the barrier layer and the surface layer becomes flat even when viewed microscopically.

On the other hand, the surface layer is formed by electroplating similarly to the barrier layer. However, as described above, the bonding surface of the barrier layer is flat and its surface area is small, so that the surface layer is not covered by the barrier layer. There is a problem that the peel strength is low.

[0005] In view of the above, it is an object of the present invention to provide a sliding member in which the structure of the barrier layer is specified to improve the peel strength of the surface layer with respect to the barrier layer.

[0006]

According to the present invention, there is provided a sliding member having a surface layer provided on a lining layer via a metal barrier layer, wherein the barrier layer is formed by deposition on the lining layer. In addition, in order to form a joint surface with the surface layer, a plurality of protrusions made of a metal crystal are provided.

[0007]

1 and 2, a sliding bearing 1 as a sliding member is applied to a journal portion of a crankshaft, a large end portion of a connecting rod and the like in an engine.
The first and second halves ₁ 1, consisting of 1 _2. Both halves 1 ₁ ,
Reference numeral ₁₂ denotes the back metal 2, a lining layer 3 formed on the inner peripheral surface of the back metal 2, a barrier layer 4 formed on the surface of the lining layer 3 by electroplating, and a barrier layer 4.
Is formed by electroplating on the surface of
And a surface layer 5 having a sliding surface 5a. Back money 2
A Cu plating layer is provided between the lining layers 3 as needed.

The back metal 2 is made of a rolled steel plate, and its thickness is determined by the set thickness of the slide bearing 1. The lining layer 3 is made of Cu, Cu-based alloy, Al, Al-based alloy, etc., and has a thickness of 50 to 500 μm, usually 300 μm.
m. The barrier layer 4 is composed of a simple substance such as Ni, Fe, Co or the like or an alloy thereof, and has a thickness of 0.1 to
5 μm, usually about 1 to 2 μm. The surface layer 5 is made of Pb
It is composed of an alloy and has a thickness of 5 to 50 μm, usually 2 μm.
It is about 0 μm.

The alloying elements in the barrier layer 4 include:
At least one selected from P, B, Co, Zn, Fe, and W can be given.
It is set to 0% by weight or less.

The Pb alloy constituting the surface layer 5 is 80 to 9
It contains 0% by weight of Pb and 3 to 20% by weight of Sn, and optionally contains Cu, In, Ag, Tl, Nb, Sb, and N.
At least one selected from i, Cd, Te, Bi, Mn, Ca, and Ba is contained in an amount of 10% by weight or less.

[0011] Cu, Ni and Mn have a function of improving the hardness of the surface layer 5, but if the content exceeds 10% by weight, the hardness becomes too high and the initial conformability decreases.
When Cu or the like is added, the hardness Hmv of the surface layer 5 is 1
It is desirable to adjust the content so as to be 5 to 25.

In, Ag, Tl, Nb, Sb, Cd, T
e, Bi, Ca, and Ba have a function of softening the surface layer 5 and improving initial conformability, but if the content exceeds 10% by weight, the strength of the surface layer 5 is reduced. When adding In or the like, it is desirable to adjust the content so that the hardness Hmv of the surface layer 5 is 8 to 15.

The plating solution for electroplating for depositing and forming the barrier layer 4 is 50 to 20 per liter.
0 g Ni ²⁺ and 30 g per liter as needed
A sulfuric acid-based plating solution containing the following ammonium chloride, boric acid, organic additives and the like is used. The pH of the plating solution is set at 3 to 6, the temperature of the plating solution is set at 10 to 60 ° C., and the cathode current density is set at 12 A / dm ² .

FIG. 3A is an electron micrograph (× 5,000) showing the crystal structure of Ni at the surface of the barrier layer 4 and thus at the joint surface 4a with the surface layer 5, and FIG.
It is a schematic diagram of the figure (a). The barrier layer 4 is deposited and formed on the Cu alloy lining layer 3, and the average cathode current density in the electroplating process when forming the barrier layer 4 is 4
A / dm ² was set.

As clearly shown in FIGS. 2 to 4, the barrier layer 4
Has quadrangular pyramid-shaped protrusions 6 made of a plurality of fine metal crystals, that is, Ni crystals, with the apex a directed toward the bonding surface 4a to form the bonding surface 4a. Each quadrangular pyramid-shaped projection 6 forms the tip of each columnar crystal 7 extending from the lining layer 3. The thickness of the barrier layer 4 is 1 to 3 μm, and the area ratio of the quadrangular pyramid-shaped projections 6 on the bonding surface 4a is 100%.

When the joining surface 4a is formed by the fine quadrangular pyramid-shaped projections 6 as described above, the surface area of the joining surface 4a is greatly increased, and the valleys between the adjacent quadrangular pyramid-shaped projections 6 are used. Since a large anchor effect is obtained, the peel strength of the surface layer 5 can be improved.

FIG. 5 shows the X of the Ni crystal in the barrier layer 4.
FIG. 4 is a line diffraction diagram, and shows (200) plane and (4) in Miller index.
Only the diffraction peak of the (00) plane is observed.

Here, an orientation index Oe is shown as an index representing the orientation of the crystal plane, (However, hkl is Miller index, Ihkl is (hkl)
Defined as the integrated intensity of the plane, ΣIhkl is the sum of Ihkl), in the (hkl) plane, its orientation index Oe is 1
The closer to 00%, the more crystal planes oriented in the direction perpendicular to the (hkl) plane.

The (200) plane and the (40) plane of the Ni crystal
Table 1 shows the integrated intensity Ihkl and the orientation index Oe on the 0) plane.

[0020]

[Table 1] From Table 1, it can be seen that the orientation index O in the (h00) plane of the Ni crystal is
e is 100%, so that the Ni crystal has crystal planes oriented in the respective axial directions at the crystal axes a, b, and c, that is, the (h00) plane. Thereby, the joining surface 4
a is a Ni crystal with the (h00) plane facing the bonding surface 4a,
Therefore, it can be seen that the projections 6 are formed from an aggregate of the quadrangular pyramid-shaped projections 6.

As described above, when the crystal plane is oriented in a direction perpendicular to the (h00) plane, the atomic structure in the orientation direction becomes high because the crystal structure of Ni is a face-centered cubic structure, and thus the barrier layer is formed. 4 is increased in hardness and its strength is improved.

FIG. 6 is an electron micrograph (× 10,000) showing the crystal structure of Ni at the joint surface of the conventional barrier layer. The barrier layer is formed on the Cu alloy lining layer by electroplating.

FIG. 7 is an X-ray diffraction diagram of the Ni crystal in the conventional barrier layer. From this figure, no orientation to a specific crystal plane is recognized. Table 2 shows the integrated intensity Ihkl and the orientation index Oe in various (hkl) planes.

[0024]

[Table 2] As is clear from FIGS. 6 and 7 and Table 2, the N
The crystal shape of i is an irregular shape in which crystal planes are randomly oriented, and therefore, the barrier layer is formed from an aggregate of granular crystals.

The plating solution for electroplating for depositing and forming the surface layer 5 includes 40 to 180 g of Pb ²⁺ per liter, 1.5 to 35 g of Sn ²⁺ per liter, and 1 liter as needed. A fluorinated plating solution containing 15 g or less of Cu ²⁺ per unit is used. The temperature of the plating solution is set at 10 to 35 ° C., and the cathode current density is set at ³ to 15 A / dm ² .

FIG. 8 is an electron micrograph (× 10,000) showing the crystal structure of the Pb alloy on the sliding surface 5a.
Is an electron micrograph (5,000 times) showing the crystal structure of the Pb alloy when the surface layer 5 is cut longitudinally. The surface layer 5 is made of a Pb alloy containing 8% by weight of Sn and 2% by weight of Cu. The surface layer 5 was deposited and formed on the barrier layer 4 having the (h00) plane orientation, and the cathode current density in the electroplating process for forming the surface layer 5 was set to 6 A / dm ² .

As clearly shown in FIG. 8 to FIG.
Has a plurality of quadrangular pyramid-shaped protrusions 8 made of a plurality of metal crystals, that is, Pb alloy crystals, with the apex b facing the sliding surface 5a to form the sliding surface 5a. Each quadrangular pyramid-shaped projection 8 forms the tip of each columnar crystal 9 extending from the barrier layer 4.

When the sliding surface 5a is formed by the plurality of quadrangular pyramid-shaped projections 8 as described above, the vertex b side of the quadrangular pyramid-shaped projections 8 is preferentially worn to improve the initial conformability of the surface layer 5. And the sliding surface 5a is formed by the quadrangular pyramid-shaped projections 8.
, The surface layer 5 can have a sufficient oil retaining property. Thereby, the surface layer 5 exhibits excellent seizure resistance.

In the quadrangular pyramid-shaped projection 8, when the preferential wear on the vertex b side is completed in the initial stage of sliding and a flat surface (corresponding to the upper bottom surface of the truncated pyramid) is formed, the flat surface Since the oil film is always present between the sliding member 5 and the mating member, the subsequent sliding surface 5a is extremely slowly worn.

FIG. 11 is an X-ray diffraction diagram of the Pb alloy crystal in the surface layer 5, where only the diffraction peaks of the (200) plane and the (400) plane are recognized by the Miller index.

Table 3 shows the integrated intensity Ihkl and the orientation index Oe of the Pb alloy crystal on the (200) and (400) planes.

[0032]

[Table 3] From Table 3, the orientation index Oe in the (h00) plane of the Pb alloy crystal is 100%.
Crystal planes oriented in each axis direction at crystal axes a, b, c,
That is, it has the (h00) plane. Thus, it can be seen that the sliding surface 5a is formed of a Pb alloy crystal with the (h00) plane facing the sliding surface, that is, an aggregate of quadrangular pyramidal projections 8.

(H0) of the Pb alloy crystal in the surface layer 5
0) The plane orientation and the adhesion of the surface layer 5 to the barrier layer 4 are promoted by the Ni crystals in the barrier layer 4 having the same orientation.

As described above, when the crystal plane is oriented in the direction perpendicular to the (h00) plane, the crystal structure of the Pb alloy is a face-centered cubic structure. The hardness of the layer 4 is increased and its seizure resistance and abrasion resistance are improved.

In the barrier layer 4, when the Ni crystal has the (h00) plane orientation as described above, the inclination angle of the quadrangular pyramid-shaped projections 6 falls within a predetermined range.

That is, as shown in FIG. 12A, an imaginary surface S along the joint surface 4a is defined on the bottom surface side of the quadrangular pyramid-shaped projection 6, and the vertex a of the quadrangular pyramid-shaped projection 6 is Assuming that the inclination angle formed by the straight line u passing through the central portion t with respect to the reference line v passing through the bottom central portion t and perpendicular to the virtual surface S is θ, the inclination angle θ of the quadrangular pyramidal projection 6 is 0 ° ≦ θ ≦ 30 °.

According to the present invention, not only the quadrangular pyramid-shaped projection 6 having the inclination angle θ as described above, but also the inclination angle θ is θ ≒ 54 ° as shown in FIG. )
Quadrangular pyramid-shaped projections 6 ₁ with its surface on the joint surface 4a side is also included.

[0038] Table 4 shows the relationship between the peel strength of the quadrangular pyramid-shaped projections 6, 6 ₁ area ratio and the surface layer 5 in the bonding surface 4a.

The peeling strength was determined by measuring the peeling width. The peeling width was measured by making a cut w on the surface layer 5 in a grid pattern as shown in FIG.
After heating at 0 ° C. for 6 hours, cooling in water, repeating this for 5 cycles as one cycle, and performing ultrasonic cavitation, the portion 5b surrounded by the cut w of the surface layer 5 becomes a barrier layer. 4, the distance from the cut w to the contact portion y was measured, and the maximum distance was defined as the peel width z.

In Table 4, the inventions (1) to (4) correspond to N
The invention corresponds to the case where the i crystal has the (h00) plane orientation, and the present inventions (5) to (7) correspond to the case where the Ni crystal has the (111) plane orientation.

[0041]

[Table 4] As is clear from Table 4, the surface layers in the present inventions (1) to (7) have superior peel strength as compared with those of the comparative examples (1) and (2). In order to obtain such peel strength, the area ratio of the quadrangular pyramid-shaped projections 6 on the bonding surface 4a is set to 1
It is better to set it to 5% or more (in this case, the rest is granular crystals of Ni alloy).

FIG. 14 shows another embodiment, in which the barrier layer 4 is formed.
Has a plurality of truncated quadrangular pyramid-shaped protrusions 10 made of fine metal crystals, that is, Ni crystals, with the upper bottom surface c facing the bonding surface 4a to form the bonding surface 4a. The present invention, the barrier layer 4 is quadrangular pyramid-shaped projections 6, 6 ₁ and truncated pyramid-shaped projections 1
The case having 0 is also included.

When at least a part of the bonding surface 4a is formed from the upper bottom surface c of the truncated quadrangular pyramid crystal 10, there is an advantage that the (h00) plane orientation of the surface layer 5 can be promoted.

In the surface layer 5, it is formed by a plurality of truncated quadrangular pyramids 11 made of a plurality of metal crystals, that is, Pb alloy crystals with the upper bottom surface d facing the sliding surface 5a to form the sliding surface 5a (FIG. 16). Reference). Surface layer 5
May have both a quadrangular pyramid-shaped projection 8 and a truncated quadrangular pyramid-shaped projection 11.

With this configuration, at least a part of the sliding surface 5a is formed by the upper bottom surface d of the truncated quadrangular pyramid-shaped projection 11, so that the mating member x and the upper bottom surface d are formed from the beginning of the sliding operation.
To form an oil film in between to improve the initial conformability and stabilize.
Can have sufficient oil retention.

The quadrangular pyramid-shaped projections 8 and / or truncated quadrangular pyramid-shaped projections 11 may form a part of the sliding surface 5a.
In this case, the area ratio of the projections 8 and 11 on the sliding surface 5a is set to 50% or more (in this case, the remainder is a granular crystal of a Pb alloy).

In order to obtain excellent sliding characteristics as described above, the inclination of the quadrangular pyramid-shaped projection 8 and the truncated quadrangular pyramid-shaped projection 11 becomes a problem.

Therefore, as shown in FIGS. 10 and 15, on the bottom surface of the quadrangular pyramid-shaped projection 8, the projection 8 is projected to define an imaginary surface E along the sliding surface 5a. Protrusion 8
The straight line h passing through the vertex b and the bottom center g is
Is defined as θ with respect to a reference line k which passes through and is perpendicular to the virtual plane E, the inclination angle θ of the quadrangular pyramidal projection 8 is 0 ° ≦
θ ≦ 30 ° is set. When the inclination angle θ becomes θ> 30 °, the oil retaining property of the surface layer 5 and the preferential wear property on the vertex b side decrease.

The inclination angle θ in the case of the truncated quadrangular pyramid projection 11 is
As shown in FIG. 16, the angle is defined as an angle between a straight line r passing through the upper bottom center n and the lower bottom center p and a reference line k passing through the lower bottom center p and perpendicular to the virtual plane E. Also in this case, the inclination angle θ is set to 0 ° ≦ θ ≦ 30 °.

In the above embodiment, the barrier layer and the surface layer are deposited and formed by electroplating. Other forming methods include a forming method via a gas phase such as PVD, ion plating, CVD, and sputtering. Can be.

The present invention is not limited to a plain bearing, but is applicable to other sliding members.

[0052]

According to the present invention, by specifying the structure of the barrier layer as described above, it is possible to provide a sliding member having improved peel strength of the surface layer from the barrier layer.

[Brief description of the drawings]

FIG. 1 is an exploded plan view of a sliding bearing.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3A is a micrograph showing a crystal structure of Ni at a bonding surface, and FIG. 3B is a schematic diagram of FIG.

FIG. 4 is a schematic perspective view of a main part showing a first example of a barrier layer.

FIG. 5 is an X-ray diffraction diagram of a Ni crystal in a first example of a barrier layer.

FIG. 6 is a micrograph showing a crystal structure of Ni at a joint surface of a conventional example.

FIG. 7 is an X-ray diffraction diagram of a Ni crystal in a conventional barrier layer.

FIG. 8 is a micrograph showing a crystal structure of a Pb alloy on a sliding surface.

FIG. 9 is a photomicrograph showing a crystal structure of a Pb alloy when a surface layer is cut longitudinally.

FIG. 10 is a schematic perspective view of a main part of a surface layer.

FIG. 11 is an X-ray diffraction diagram of a Pb alloy crystal on a surface layer.

FIG. 12 is an explanatory diagram showing types of quadrangular pyramid-shaped projections in a barrier layer.

FIG. 13 is an explanatory diagram of a peeling test.

FIG. 14 is a schematic perspective view of a main part showing a second example of the barrier layer.

FIG. 15 is an explanatory diagram showing a method for measuring the inclination angle of a quadrangular pyramid-like projection on a surface layer.

FIG. 16 is an explanatory view showing a method of measuring the inclination angle of a truncated quadrangular pyramid projection on a surface layer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Slide bearing (sliding member) 4 Barrier layer 4a Joining surface 5 Surface layer 5a Sliding surface 6,6 ₁ Quadrangular pyramid projection 10 Quadrangular truncated pyramid projection x Counterpart member

────────────────────────────────────────────────── (5) References JP-A-5-25682 (JP, A) JP-A-62-124321 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16C 33/12 F16C 33/10 C25D 7/00

Claims (2)

(57) [Claims] 1. A sliding member having a surface layer (5) provided on a lining layer (3) via a metal barrier layer (4), wherein the barrier layer (4) is provided on the lining layer (3). Having a plurality of protrusions (6, 6 ₁ , 10) made of metal crystals to form a bonding surface (4a) with the surface layer (5). Moving member. 2. A sliding member having a metal surface layer (5) provided on a lining layer (3) with a metal barrier layer (4) interposed therebetween, wherein the barrier layer (4) is provided on the lining layer (3). ), A plurality of metal crystal projections with the (h00) plane oriented toward the bonding surface with a Miller index to form a bonding surface (4a) with the surface layer (5). (6, 6 ₁ , 10) and the surface layer (5)
Is formed by precipitation on the lining layer (3), and the (h00) plane is shifted to the sliding surface side by the Miller index so as to form the sliding surface (5a) with the mating member (x). A sliding member having a plurality of metal crystals directed to the sliding member.