JP3057457B2 - 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 of a sliding member, particularly a sliding member having a substrate containing Pb and a surface layer formed on the substrate and having a sliding surface with a mating member. About.

[0002]

2. Description of the Related Art Conventionally, as this kind of sliding member, there has been known a sliding bearing in which the surface layer is formed by an electroplating method.

[0003]

However, Pb has poor wettability with other metals, and in the prior art, a coarse Pb phase exists in a dispersed state at the interface with the surface layer of the substrate. In addition, there is a problem that adhesion of the surface layer to the substrate is poor.

[0004] In view of the above, it is an object of the present invention to provide the sliding member in which the adhesion of the surface layer to the substrate is improved and the peel strength of the surface layer is improved.

[0005]

According to the present invention, there is provided a sliding member comprising a substrate containing Pb and a surface layer formed on the substrate and having a sliding surface with a mating member. The density of the Pb phase dispersed at the interface with the surface layer is 2,500
It is characterized in that the number is set to not less than pcs / mm ^{2 and not} more than 6,000 pieces / mm ² .

[0006]

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 ,
By abutting the _two end faces of each other, an annular substrate 2 located on the outside is formed, and a surface layer 3 having a sliding surface 3a with the mating member x is formed on the inner peripheral surface of the substrate 2. Is done. The substrate 2 has a backing metal 2 _1, is formed on the back metal 2 ₁ inner circumferential surface, the lining layer 2 ₂ for supporting the surface layer 3.
Copper plating layer between the backing metal 2 ₁ and the lining layer 2 _2,
Also between lining layers 2 ₂ and the surface layer 3 provided as necessary nickel plating barrier layer, respectively.

[0007] backing metal 2 ₁ is composed of rolled steel plate, the thickness thereof is determined by setting the thickness of the sliding bearing 1. Lining layer 2 ₂ is composed of an alloy containing Pb, its thickness is 50 to 500 [mu] m, usually about 300 [mu] m.
Thus the lining layer 2 _2, the reason for constituting an alloy containing Pb, when the mating member x and the lining layer 2 ₂ worn surface layer 3 by long-term use has solid contact,
This is to avoid the occurrence of a rapid seizure phenomenon due to the solid lubrication effect of Pb. The surface layer 3 is made of a Pb alloy and has a thickness of 5 to 50 μm, usually 20 μm.
m.

[0008] As an alloy constituting the lining layer 2 _2, for example, Cu-Pb-Sn-based alloy is used. It is hitting the formation of the lining layer 2 _2, particle size 45μm or more, 1
The following alloy powder 50 wt% and the alloy powder 50% by weight and more become mixed powder of particle size less than 45 [mu] m 50 [mu] m, the backing metal 2 ₁
700 to 830 on a steel strip (rolled steel sheet)
Primary sintering at 20 ° C for 20 to 40 minutes, reduction ratio 30
Primary rolling under the condition of ~ 50%, 700 ~ 830 ° C,
Perform secondary sintering under the conditions of 20 to 40 minutes, reduction ratio 8 to 1
Means such as performing secondary rolling under the condition of 8% is employed.

The Pb alloy constituting the surface layer 3 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.

[0010] Although Cu, Ni and Mn have a function of improving the hardness of the surface layer 3, if the content exceeds 10% by weight, the hardness becomes too high and the initial conformability is lowered.
When Cu or the like is added, the hardness Hmv of the surface layer 3 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 3 and improving initial conformability, but if the content exceeds 10% by weight, the strength of the surface layer 3 is reduced. When adding In or the like, it is desirable to adjust the content thereof so that the hardness Hmv of the surface layer 3 becomes 8 to 15.

The surface layer 3 is formed by an electroplating method, and a plating solution is 40 to 1 per liter.
80 g of Pb ²⁺ , 1.5 to 35 g of Sn per liter
^2+, borofluoride based plating solution comprising the following Cu ²⁺ 15 g per liter, are used as occasion demands. The temperature of the plating solution is 10 to 35 ° C., and the cathode current density is 3 to 15 A / d.
Each is set to m ^2.

FIG. 3 is an electron micrograph (× 10,000) showing the crystal structure of the Pb alloy on the sliding surface 3a. FIG. 4 is an electron microscope showing the crystal structure of the Pb alloy when the surface layer 3 is longitudinally cut. These are micrographs (enlarged images taken at 5,000 times).

As apparent from FIGS. 3 to 5, the surface layer 3
Has a plurality of pyramid-shaped projections with the apex a directed toward the sliding surface 3a, in the illustrated example, quadrangular pyramid-shaped crystals 5 in order to form the sliding surface 3a. forming the tip end portion of each columnar crystal 4 extending from the lining layer 2 _2.

The composition of the surface layer 3 is 8% by weight Sn, 2% by weight Cu, and the balance Pb. The composition of the lining layer 2 _2, 19 wt% Pb, 7 wt% Sn, the balance Cu.
Backing metal 2 ₁ is constituted of a rolled steel plate (JIS SPCC material).

FIG. 6 is an X-ray diffraction diagram of the Pb alloy crystal in the surface layer 3, in which only the diffraction peaks of the (200) plane and the (400) plane are recognized by the Miller index.

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 Pb alloy crystal
Table 1 shows the integrated intensity Ihkl and the orientation index Oe on the 0) plane.

[0019]

[Table 1]

From Table 1, the orientation index Oe of the (h00) plane of the Pb alloy crystal is 100%.
The alloy crystal has crystal planes oriented in each axial direction at crystal axes a, b, and c, that is, (h00) plane.

As described above, when the crystal plane is oriented in a direction orthogonal to the (h00) plane, the crystal structure of the Pb alloy is a face-centered cubic structure. 3 increases in its seizure resistance.

As clearly shown in FIG. 2, the lining layer 2 ₂
Has a number of Pb phase 6 dispersed therein, some ones among the Pb phase 6, the boundary surface 7 between the surface layer 3, also some things respectively dispersed state boundary surface 8 of the backing metal 2 ₁ Exists.
The density of the Pb phase 6 dispersed on both boundary surfaces 7 and 8 is respectively
It is set to 2,500 pieces / mm ² or more and 6,000 pieces / mm ² or less (in this case, if the density of Pb phase 6 per 1 mm ² is low,
Lower means that the Pb phase 6 is coarser). Such miniaturization of the Pb phase 6 can be achieved by employing means such as miniaturizing the alloy powder to be used or lowering the sintering temperature by specifying the composition of the alloy powder.

As described above, when the Pb phase 6 is miniaturized,
Adhesion of the surface layer 3 and the backing metal 2 ₁ for lining layer 2 ₂ is improved, it is possible to improve the peel strength of the surface layer 3 and the backing metal 2 _1. However, the density of the Pb phase 6 is
When less than 2,500 / mm ^2, since the peel stress to the Pb phase 6 with the coarsening of the Pb phase 6 is concentrated, the peel strength of the surface layer 3 and the backing metal 2 ₁ decreases. On the other hand, when the number exceeds 6,000 / mm ² , the occurrence of nests in the surface layer 3 is remarkably observed.

FIG. 7 (a) is a photomicrograph showing the metallographic lining layer 2 ₂ of the present invention (400 ×), the density of the Pb phase 6 black dispersed in the boundary surface 7 4,000
Pieces / mm ² . 7 (b) is a photomicrograph showing the metallographic lining layer 2 ₂ in the prior art (400-fold), the density of the Pb phase 6 black dispersed in the boundary surface 7 1,50
0 pieces / mm ² .

7 (a) and 7 (b), it can be seen that the Pb phase 6 is finer in the present invention.

[0026] Figure 8 shows the density of the Pb phase 6 in the lining layer 2 ₂ of the surface layer 3 side boundary surface 7, the relationship between the peeling width of the surface layer 3. The measurement of the peel width is performed by making a cut b in a grid pattern on the surface layer 3, heating at 180 ° C. for 6 hours, cooling in water, and repeating this as one cycle for 5 cycles.
After each operation such as performing ultrasonic cavitation,
The portion c surrounded by the cut b in the surface layer 3 is the lining layer 2
When peeling from _2, the distance from the cut b to the contact portion d was measured, and the maximum distance was taken as the peel width e.

FIG. 8 shows that the density of the Pb phase 6 at the boundary surface 7 is suitably not less than 2,500 / mm ^{2 and not} more than 6,000 / mm ² , preferably not less than 3,000 / mm ² and 6,000 / mm ^2.
2 or less. The density of Pb phase 6 is 900 / mm ² or more,
The range of less than 2,500 pieces / mm ² is the conventional level. Tendency of Figure 8 is also true for the back metal 2 ₁ side boundary surface 8.

[0028] When forming the surface layer 3 by electroplating, the lining layer 2 _2, etching treatment using an acid, although pretreatment of electrolytic etching or the like is performed, during the pretreatment, the lining layer some or all of the Pb phase 6 2 ₂ of the surface layer 3 side boundary surface 7 may leach into the processing solution.

When such a phenomenon occurs and the density of the Pb phase 6 is at the conventional level, a deep recess 9 having a large opening is formed at the boundary surface 7 as shown in FIG. Each columnar crystal 4 grown from the bottom surface of the recess 9 has a large inclination. As a result, the surface layer 3 is a mixture of a columnar crystal group that has grown substantially straight and a columnar crystal group that has an inclination.

The reason for forming the sliding surface 3a from the quadrangular pyramidal crystals 5 as described above is that the surface area of the sliding surface 3a is enlarged so that the surface layer 3 has sufficient oil retaining properties, that is, oil retaining properties. Another object is to preferentially wear the vertex a side of the quadrangular pyramidal crystal 5 to improve the initial conformability of the surface layer 3.

Therefore, the presence of the columnar crystals having a large inclination as described above is an obstacle to improving the sliding characteristics of the surface layer 3.

In the present invention, as described above, the Pb phase 6
As shown in FIG. 10, the concave portion 10 becomes shallow with an extremely small opening. As a result, each columnar crystal 4 grown from the bottom surface of the concave portion 10 does not tilt or tilts. However, the inclination is extremely small, and the number of inclined columnar crystals 4 is also small.

Thus, it is possible to form the surface layer 3 having excellent sliding characteristics utilizing the characteristics of the quadrangular pyramidal crystal 5.

[0034] Table 2, in the present invention and comparative examples sliding bearing, the physical properties of their surface layer 3, the seizure generating surface pressure density and the surface layer 3 of the recess 9, 10 in the lining layer 2 _second boundary surface 7 It is a comparison. The density of the recess is P
It corresponds to the density of the b-phase.

The seizure test was performed by rubbing each sliding bearing against the rotating shaft and gradually increasing the load applied to the sliding bearing. The values in Table 2 are obtained by determining the surface pressure when each surface layer causes seizure.

The test conditions are as follows. Material of rotating shaft JIS S48C material subjected to nitriding treatment, rotation speed of rotating shaft 6000 rpm, lubrication temperature 120 ° C, lubrication pressure 3 kg / cm ² , load 1 kg / sec.

[0037]

[Table 2]

As is clear from Table 2, the present invention has better seizure resistance than the comparative example. This is because, in the present invention, each columnar crystal 4 does not tilt, or the tilt is extremely small even if the concave portion 10 of the boundary surface 7 has a very small opening and is shallow. Is also very small.

FIGS. 11 and 12 (10,000 times electron micrograph) show that the surface layer 3 has a plurality of truncated pyramid-shaped protrusions with the upper bottom surface f facing the sliding surface 3a in order to form the sliding surface 3a. In the illustrated example, only the truncated pyramidal crystal 11 of the Pb alloy is shown, and the same sliding characteristics as described above can be obtained by such a crystal 11 or a hybrid structure of the crystal 11 and the pyramidal crystal 5. . In this case, since at least a part of the sliding surface 3a is formed from the upper bottom surface f of the truncated quadrangular pyramid crystal 11, an oil film is formed between the mating member and the upper bottom surface f from the initial stage of the sliding to start the initial operation. The conformability can be improved and stabilized.

The quadrangular pyramidal crystal 5 and / or the truncated quadrangular pyramid crystal 11 may be present in a dispersed state so as to form a part of the sliding surface 3a. In this case, the area ratio of the pyramidal crystals 5 and the like on the sliding surface 3a is set to 50% or more.

The following can be said about the inclination of the pyramidal crystal 5 and the truncated pyramid crystal 11 on the sliding surface 3a.

That is, as shown in FIGS. 5 and 13, the sliding surface 3 is formed by projecting the crystal 5
A imaginary plane G along a is defined, and a straight line k passing through the apex a of the quadrangular pyramid-shaped crystal 5 and the bottom center part h forms a reference line m passing through the bottom center part h and perpendicular to the imaginary plane G. When the tilt angle is defined as θ, the tilt angle θ of the quadrangular pyramidal crystal 5 is 0 ° ≦ θ ≦
It is set to 30 °. This is because, when the inclination angle θ becomes θ> 30 °, the oil retaining property of the surface layer 3 and the preferential wear property on the vertex a side decrease.

The inclination angle θ in the case of the truncated pyramid crystal 11 is
As shown in FIGS. 11 and 14, 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 m passing through the lower bottom center p and perpendicular to the virtual plane G. Also in this case, the inclination angle θ is set to 0 ° ≦ θ ≦ 30 °.

In the above embodiment, the surface layer was formed by the electroplating method.
A formation method via a gas phase such as VD, ion plating, CVD, and sputtering can be given. In forming the pyramidal projections on the sliding surface, it is possible to apply etching methods such as chemical etching, electric etching, vapor phase etching (bombarding), and mechanical processing such as transfer and cutting. is there.

[0045] Further, the hitting to the formation of the lining layer 2 _2, for example of 10 to 40 wt% Pb and 0.5 to 10
Cu-Pb- for casting containing Sn by weight as an essential chemical component
Sn system using an alloy, from backing metal 2 ₁ become strip (rolled steel) one side is heated to 200 to 500 ° C. to the other side towards 2m /
min and then on the strip, 1050 to 1
It is also possible to adopt a method in which a molten metal of a Cu-Pb-Sn-based alloy at 150 ° C is continuously flowed down so that its thickness becomes about 0.8 mm, and then the molten metal is rapidly cooled by cooling water. is there.

The present invention is not limited to the plain bearing, but is applicable to other sliding members. Also the substrate 2 also includes those without lining layer 2 _2.

[0047]

According to the present invention, a sliding member having an improved peel strength between the surface layer and the backing metal is provided by specifying the density of the Pb phase at the interface between the substrate and the lining layer as described above. be able to. Further, when the surface layer is formed by the electroplating method, it is possible to provide a sliding member capable of avoiding inconveniences such as a decrease in the sliding characteristics of the surface layer caused by the dissolution of the Pb phase.

[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. 3 is a micrograph showing a crystal structure of a Pb alloy on a sliding surface.

FIG. 4 is a photomicrograph showing a crystal structure of a Pb alloy when a first example of a surface layer is longitudinally cut.

FIG. 5 is a schematic perspective view of a main part showing a first example of a surface layer.

FIG. 6 is an X-ray diffraction diagram of a Pb alloy crystal in the first example of the surface layer.

FIG. 7 (a) is a micrograph showing a metal structure of a lining layer in the present invention, and FIG. 7 (b) is a micrograph showing a metal structure of a lining layer in a conventional example.

FIG. 8 is a graph showing the relationship between the density of a Pb phase at a boundary surface and the separation width of a surface layer.

FIG. 9 is a schematic vertical sectional view of a main part of a comparative example surface layer.

FIG. 10 is a schematic longitudinal sectional view of a main part of a surface layer to which the present invention is applied.

FIG. 11 is a schematic perspective view of a main part showing a second example of the surface layer.

FIG. 12 is a micrograph showing a crystal structure of a Pb alloy corresponding to FIG.

FIG. 13 is an explanatory view showing a method of measuring the inclination angle of a pyramidal crystal.

FIG. 14 is an explanatory diagram showing a method of measuring the inclination angle of a truncated quadrangular pyramid crystal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Slide bearing (sliding member) 2 Substrate 2 ₁ Backing metal 2 ₂ Lining layer 3 Surface layer 3a Sliding surface 4 Columnar crystal 6 Pb phase 7, 8 Boundary surface x Partner member

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // C10N 10:08 40:02 50:08 70:00 (56) References JP-A-3-232905 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) F16C 33/12

Claims (3)

(57) [Claims] A sliding surface (3) between a substrate (2) containing Pb and a mating member (x) formed on the substrate (2).
a) having a surface layer (3) having a)
The density of the Pb phase (6) dispersed on the interface (7) of the substrate (2) with the surface layer (3) is 2,500 particles / mm ² or more.
A sliding member characterized in that the number is set to 000 pieces / mm ² or less. 2. A back metal (2 ₁ ), a lining layer (2 ₂ ) containing Pb formed on the back metal (2 ₁ ), and a mating member ( ₂ ) formed on the lining layer (2 ₂ ). x)
And a surface layer (3) having a sliding surface (3a) with the surface layer (3) of the lining layer (2 ₂ ) and the back metal (2 ₁ ). A sliding member characterized in that the density of the Pb phase (6) in (7, 8) is set to 2,500 pieces / mm ² or more and 6,000 pieces / mm ² or less, respectively. The surface layer (3) is formed by an electroplating method, and comprises a plurality of alloy columnar crystals (4) extending from the substrate (2) or the lining layer (2 ₂ ). The sliding member according to claim 1, comprising: