JPH04331817A - Sliding bearing having composite plating film - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance without deteriorating non-seizure characteristic and fatigue-resistance by forming a Pb alloy surface layer which includes a specified ratio of inorganic grains as a composite plating film of a bearing main body, while specifying a mean diameter of the inorganic grains and a surface roughness of the composite plating film, respectively. CONSTITUTION:In a sliding bearing used in an internal combustion engine or the like, for instance, a sliding bearing of two-layer structure, a Pb alloy layer 1 such as Pb-Sn, Pb-Sn-Cu, Pb-Sn-Sb, Pb-Sn-Zn, Pb-Sn-In, including one or two selected from inorganic grains such as BN, SiC, MoS is laminated on a Cu alloy layer 3 such as Cu-Pb Cu-Pb-Sn, Cu-Zn, Su-Sn. That is, a composite plating film is formed by the Pb alloy layer 1. The ratio of the inorganic grains is set between 0.3 and 25 percent by volume. A mean diameter of the inorganic grains is 1.5m or lower, while a surface roughness of the composite plating film is Rz4mum or lower.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding bearing for an internal combustion engine, and more particularly to a sliding bearing suitable for high-speed, high-load engines that have been required to increase the output of internal combustion engines in recent years.

0002

[Prior Art] Sliding bearings used in internal combustion engines, etc.
Usually, a bimetal made by bonding a bearing copper alloy or aluminum alloy onto a steel plate is processed into a cylindrical bush or half metal shape, and the bearing alloy side is coated with a lead alloy plating film. Here, the main functions of the lead alloy plating layer are: ■ Improving the compatibility between the bearing and the shaft such as the crankshaft, ■ Burying foreign matter mixed in the lubricating oil in the lead alloy plating layer, ■ In particular, for copper bearing alloys, it is important to protect them from organic acids produced by deterioration of lubricating oil. For this purpose, lead alloy plating is described in U.S. Pat. No. 2,605,149, U.S. Pat.
As seen in disclosures such as Publication No. 8, Sn, Cu,
BACKGROUND ART Sliding bearings equipped with lead alloy plating layers having various amounts of added alloy components such as In have been proposed, manufactured, and used.

0003

[Problems to be Solved by the Invention] However, in recent automobile engines, bearings are used at high speeds and under heavy loads in order to pursue higher output and lower fuel consumption. Wear progresses rapidly, and there are problems such as seizure due to abrasion of the plating layer, or, even if it does not lead to seizure, metal tapping noise caused by an increase in the oil clearance between the shaft and the bearing. In addition, under heavy load operation in diesel truck engines, the problem of corrosion and seizure of the copper alloy layer for bearings after wear of the lead alloy plating layer has been highlighted, and this has caused problems in terms of the durability of internal combustion engines.
In particular, there is a demand for a lead alloy plating layer with excellent wear resistance, but it has been difficult to obtain wear resistance that fully satisfies this demand even if various combinations of components in the lead alloy are changed. .

[0004] In response to such demands, lead alloy plating layers containing various inorganic particles have been proposed, but simply dispersing inorganic particles within the lead alloy plating layer results in coarse surface roughness. Therefore, when the internal combustion engine starts operating, the frictional force generated when the shaft and the bearing come into direct contact increases, resulting in the engine not operating smoothly. Also,
Even if operation is started after a long period of break-in operation has achieved good conformity, the oil film pressure, which changes over time, causes a localized concentrated load on the coarse inorganic particles in the lead alloy plating layer. will be added. By repeating this load application, the lead alloy plating layer gradually fatigues starting from the vicinity of the inorganic particles, and as the fatigue progresses, the inorganic particles near the inorganic particles that appear on the sliding surface of the lead alloy plating layer containing inorganic particles become fatigued. The fatigued areas gradually become connected, and the fatigued areas of the lead alloy plating layer will fall off as a whole. In addition, even under loads that do not reach fatigue, large surface roughness inhibits the formation of an oil film between the shaft and bearing of an internal combustion engine.
High-speed rotation and high-load operation are difficult, and the scope of application of lead alloy plating layers containing inorganic particles is limited. The present invention was devised against such a technical background, and is intended to be applied with a composite plating film that exhibits the excellent wear resistance of the composite plating film without impairing its anti-seizure properties and fatigue resistance. Its purpose is to provide a sliding bearing.

[0005]

[Means for Solving the Problems and Their Effects] The object is to provide a sliding bearing provided with a lead alloy surface layer containing inorganic particles of 0.3 to 25% by volume as an average composition in the layer thickness direction. , a composite plating film in which a lead alloy surface layer containing inorganic particles is attached to a bearing main body member, the average particle size of the inorganic particles is 1.5 μm or less, and the surface roughness of the composite plating film is Rz 4 μm or less This is achieved by providing a plain bearing with a

The sliding bearing of the present invention typically includes a steel back metal, a bearing copper alloy layer or an aluminum alloy layer provided on the back metal, and a composite plating film provided on the copper alloy layer. Provided as a laminate. The total amount of lead alloy constituting the matrix of the composite plating film is 2 to 2.
Preferably, the material contains 30% by weight of one or more of Sn, In, Sb, Cu and Zn. It is preferable to interpose an intermediate plating layer with a thickness of 0.5 to 5 μm between the composite plating film and the alloy layer (bearing copper alloy layer or aluminum alloy layer) that is the lower layer of the composite plating film. and the intermediate plating layer is made of Ni, Ni alloy,
Co, Co alloy, Fe, Fe alloy, Cu, Cu alloy, A
It is made of one kind of metal selected from the group consisting of Ag and Ag alloys. Further, it is preferable to interpose a bonding metal layer between the backing metal and the alloy layer (bearing copper alloy layer or aluminum alloy layer) for bonding both layers, and the bonding metal layer is made of Ni, Ni alloy, Cu, Cu
It is made of one metal selected from the group consisting of alloys, Al, and Al alloys.

The present inventors conducted sliding tests under various conditions on test pieces with composite plating films on lead alloy substrates containing various inorganic particles, and observed the surfaces of the composite plating films before and after the tests. Analyzed. The results are as follows. There is a positive proportional relationship between the average particle diameter of various inorganic particles and the surface roughness of a composite plating film made by co-depositing the particles into a lead alloy plating layer using a composite plating method. A correlation with the initial friction coefficient at the start of the dynamic test is clearly recognized. The average particle size of inorganic particles is 1.5 μm.
and the surface roughness of the composite plating film surface layer is Rz
The sliding test piece with a composite plating film of 4 μm or less has a low initial coefficient of friction, and oil film formation occurs smoothly from the start of operation, so the amount of wear in the initial stage of friction is kept low, and then the wear progresses to normal wear. Even after this, the action of the inorganic particles contained in the composite plating film results in a lead alloy plating layer with extremely excellent wear resistance, making it possible to extend the life of sliding bearings for internal combustion engines.

Next, the reasons for limiting each component, bearing structure, etc. in the present invention will be described. The inorganic substance used in the present invention is
Nitride (e.g. BN, TiN, CuN, etc.), carbide (
For example, SiC, TiC, B4 C, TaC, etc.), fluorides (for example, (CF)n, CaF2, etc.), sulfides (
For example, MoS2, WS2, etc.), and others, and are not particularly limited.

Regarding the content of inorganic particles, the average composition in the thickness direction of the composite plating film is 0.3% by volume.
If it is less than 25%, the effect of improving wear resistance will be small, and the average composition will be less than
If the amount exceeds % by volume, the composite plating film itself will lose its toughness, resulting in a lack of fatigue resistance and, as a result, loss of wear resistance. Therefore, the content of inorganic particles is limited to an average composition of 0.3 to 25% by volume, and a more preferable average composition is 0.5 to 20% by volume.

Regarding the average particle size of the inorganic particles and the surface roughness of the composite plating film, in automobile sliding bearings, the lead alloy plating layer generally needs to have a thickness of 10 to 30 μm, and the surface smoothness is also required. required. Here, in order to set the thickness of the composite plating film to 10 to 30 μm and obtain a surface with a particularly low initial coefficient of friction, the average particle size of the inorganic particles should be set to 1.5 μm or less, and the resulting composite plating film It is necessary to make the surface roughness Rz 4 μm or less. In a composite plating film obtained using inorganic particles having a particle size exceeding 1.5 μm, it is difficult to make the surface roughness fine, and a film with a low initial coefficient of friction cannot be obtained. Therefore, the average particle diameter of the inorganic particles is limited to 1.5 μm or less, and the surface roughness of the composite plating film is limited to Rz 4 μm or less.

Additive metal Sn of the base lead alloy of the plating film,
If the total content of In, Sb, Zn, and Cu is less than 2% by weight, mechanical strength, such as hardness and tensile strength, will be low, and corrosion resistance against organic acids that occur when lubricating oil deteriorates. It will lack sex. If the total amount exceeds 30% by weight, especially in the temperature range 1 where plain bearings are used.
Sn, In, and Sb added to the lead alloy plating film significantly reduce the mechanical strength at 00 to 130°C.
The total content of one or more of , Zn and Cu is limited to 2 to 30% by weight, and the most preferable total content is 5 to 25% by weight.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 8 are schematic diagrams showing longitudinal cross-sectional structures of sliding bearings according to the present invention each having a composite plating film as a surface layer. Figure 1 shows Cu-Pb system, C
BN, SiC, (CF)n, M
Pb-Sn, Pb-Sn-Cu, Pb-Sn containing one or more selected from inorganic particles such as oS2
-Pb such as Sb, Pb-Sn-Zn, Pb-Sn-In, etc.
An example in which alloy layers 1 are laminated is shown. FIG. 2 shows an example in which the Cu alloy layer 3 and the Pb alloy layer 1 shown in FIG. 1 are laminated on a steel backing metal 4 made of low carbon steel, high carbon steel, stainless steel, special steel, or the like. FIG. 3 shows that Ni, Co, Fe, A
An example is shown in which the intermediate layer 2 is made of either g, Cu, or an alloy thereof. 4, an intermediate layer 2A made of any one of Ni, Co, Fe, Ag, Cu, or an alloy thereof, which is different from the intermediate layer 2, is provided between the intermediate layer 2 and the Cu alloy layer 3 in FIG. In addition, a Sn plating film or a Pb coating is applied to the surface of the steel back metal 4 for rust prevention purposes.
- An example in which a Sn plating film 7 is attached is shown. Figure 5 shows
An example is shown in which a Pb alloy layer 1 is laminated on an Al alloy layer 5 of Al-Sn, Al-Si, Al-Zn, or the like. FIG. 6 shows that the Cu alloy layer 3 in FIG. 4 is replaced by the Al alloy layer 5.
An example equivalent to replacing with is shown below. Figure 7 shows
Between the steel back metal 4 and the Al alloy layer 5, Cu, Ni, Al
Alternatively, a bonding layer 6 made of an alloy thereof is provided, and an intermediate layer 2 (the material is as described above) is provided between the Al alloy layer 5 and the Pb alloy layer 1. Figure 8 shows
In the example shown in FIG. 6, the intermediate layer 2A is omitted, and the surface of the steel back metal 4 is coated with a Sn plating film or Pb for rust prevention.
- An example in which a Sn plating film 7 is attached is shown.

Test Example 1: Copper alloy powder (Cu-2
A sintered layer was provided by sintering 3Pb-3.5Sn) to produce a bimetal. Next, the obtained bimetal was cut and subjected to a machining process to produce a Suzuki type friction and wear test piece (hereinafter referred to as a test piece). The test piece was subjected to pretreatment in the order of normal solvent degreasing, electrolytic degreasing, and pickling, and then plating treatment was performed on the sintered copper alloy surface under the following conditions. Plating conditions: Normal Watt Ni plating bath, bath temperature 50℃,
Cathode current density 6 A/dm2. A Ni intermediate plating layer with a thickness of 1.5 μm was provided on the copper alloy surface in advance, and S with different average particle sizes was placed in a normal borofluoride lead alloy plating bath.
Using iC (carbide) as inorganic particles, 15-25g
/liter of SiC is dispersed in a plating bath and electrolyzed at a bath temperature of 25°C and a cathode current density of 3 to 5 A/dm2 to form a composite plating film consisting of co-deposited inorganic particles and a base lead alloy layer. I got it. The thickness of each layer is 20 μm of the composite plating film, 0.3 mm of the copper alloy layer, and 1.2 mm of the steel backing layer. Table 1 shows the particle size, co-precipitated amount, and composition of the lead alloy as the plating film substrate in each test conducted under different conditions (see Samples Nos. 1 and 2. Samples Nos. 3 and 4 are comparative examples). ).

Test Example 2: Using the same test piece as Test Example 1, the same pretreatment (applying the same sintered layer as in Example 1) was performed on it, and Watt Ni plating (Ni intermediate plating) was applied to it. After that, using Si3N4 (nitride) with different average particle sizes as inorganic particles, 30 to 50 g/liter of them were dispersed in a lead alloy plating bath, and a composite plating film was obtained in the same manner as in Test Example 1. Ta. The thickness of each layer is the same as in Test Example 1, and the particle size, amount of eutectoid, and lead alloy plating composition are shown in Table 1 (see Sample Nos. 5 and 6. Sample No.
7 and 8 are comparative examples).

Test Example 3: For comparison with the conventional product, a test piece similar to that in Test Example 1 was used, pretreated (applied with a sintered layer similar to Test Example 1), and inorganic particles were added to it. Electrolysis was performed using a lead-free plating bath to obtain a surface layer having the composition shown in Table 1. (See Sample Nos. 9-11). The thickness of each layer is the same as in Test Example 1.

Test Example 4: A thin plate of an aluminum alloy for bearings (Al-6Sn-1Cu-1Ni) was rolled and bonded to a steel back metal by a roll rolling method, and then annealed at a temperature of 350°C for 4 hours to produce a bimetal. . Next, the obtained bimetal was cut and machined in the same manner as in Test Example 1 to prepare a test piece. Then normal solvent degreasing,
After sequentially performing alkaline etching, pickling, and zinc replacement treatment, which are commonly known pretreatments on Al alloys, plating was performed using a Watt Ni plating bath at a bath temperature of 50°C and a cathode current density of 6.
Electrolysis was carried out under the conditions of A/dm2, resulting in a thickness of 2.
A 0 μm Ni interlayer was applied. Next, in the same manner as in Test Example 1, using SiC with an average particle size of 1.0 μm, 0.5 to 50 g/liter of SiC was dispersed in a plating bath, and the bath temperature was 25° C. and the cathode current density was 3 to 5. Electrolysis was performed under conditions of A/dm2 to co-deposit SiC, which is an inorganic particle, to obtain a composite plating film. The thickness of each layer is the composite plating film 2
0 μm, aluminum alloy layer 0.3 mm, steel backing layer 1.
It is 2mm. The amount of co-precipitation and the lead alloy plating composition are shown in Table 1 (see Sample Nos. 13 to 15. Sample No. 12 is a comparative example).

Test Example 5: Using the same test piece as in Test Example 4, and performing the same pretreatment, using a cyanide copper strike plating bath that is applied to ordinary Al alloys, the bath temperature was 50°C.
℃ and a cathode current density of 1.5 A/dm2 to form a 2.0 μm thick Cu intermediate layer.
50 to 100 g/liter of inorganic particles similar to the above were dispersed in a plating bath at a bath temperature of 25°C and a cathode current density of 3 to 5.
Electrolysis was performed under the conditions of A/dm2 to co-deposit SiC, which is an inorganic particle, to obtain a composite plating film. The thickness of each layer is the same as Test Example 4, and the amount of eutectoid and lead alloy plating composition are shown in Table 1 (see Sample No. 16. Sample No. 17 is a comparative example).

Test Example 6: Composite plating films obtained by dispersing various inorganic particles in a plating bath using the same method as in Test Examples 1 to 5 are shown in Table 1 (Sample No.
．． 18-20). Furthermore, a seizure test and a wear test were conducted to confirm the effectiveness of each sample. The test conditions are shown in Table 2, and the results are shown in Figures 9, 10, and 11.
are summarized in

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Effect of the invention] As can be seen from the surface roughness of each sample shown in Table 1, when the average particle size of the inorganic particles was 1.5 μm or less, the surface roughness of the composite plating film was Rz 4 μm or less. Therefore, these samples have a low coefficient of friction at the time of initial break-in as shown in FIG. 10, and this effect allows smooth oil film formation and high seizure surface pressure. Furthermore, if the average particle size of the inorganic particles exceeds 1.5 μm, it is difficult to reduce the surface roughness of the composite plating film to Rz 4 μm or less, and the coefficient of friction at the initial break-in stage becomes high (Fig. 10), resulting in It is understood that seizure occurs at low surface pressures. The average particle size of inorganic particles is 1.5
Even if it is less than μm, if the amount of co-precipitation exceeds 25% by volume, the surface roughness of the composite plating film will exceed Rz 4 μm, and seizure will occur at a low surface pressure. Furthermore, as can be seen from the wear test results shown in FIG.
The products of the present invention, which are coated with a composite plating film of 4 μm or less, exhibit less wear compared to products that do not contain inorganic particles, and products that contain particles that fall outside the range of 0.3 to 25% by volume. It can be seen that the amount is decreased, and it is extremely effective in improving wear resistance. It is thus understood that the product of the present invention is a composite plated sliding bearing having extremely excellent wear resistance and anti-seizure properties.

[Brief explanation of drawings]

FIG. 1: 2 having a copper alloy layer according to an embodiment of the present invention.
A cross-sectional view of the main parts of a layered plain bearing.

FIG. 2 is a sectional view of a waist portion of a three-layer sliding bearing according to an embodiment of the present invention.

FIG. 3 is a diagram showing a modification of the bearing shown in FIG. 2;

FIG. 4 is a diagram showing a modification of the bearing shown in FIG. 3;

FIG. 5 is a sectional view of a main part of a two-layer sliding bearing having an aluminum alloy layer according to an embodiment of the present invention.

FIG. 6 is a sectional view of a main part of a five-layer sliding bearing according to an embodiment of the present invention, in which an aluminum alloy layer is provided on a steel back metal.

7 is a diagram showing a modification of the bearing shown in FIG. 6. FIG.

8 is a diagram showing a modification of the bearing shown in FIG. 7. FIG.

FIG. 9 is a bar graph showing seizure test results.

FIG. 10 is a bar graph showing the initial friction coefficient of each test piece.

FIG. 11 is a bar graph showing wear test results.

[Explanation of symbols]

1 Pb alloy layer 2 Middle class 2A Middle class 3 Cu alloy layer 4 Steel back metal 5 Al alloy layer 6 Bonding layer

Claims (6)

[Claims] Claim 1: The average composition in the layer thickness direction is 0.
In a sliding bearing provided with a lead alloy surface layer containing 3 to 25% by volume of inorganic particles, the lead alloy surface layer containing inorganic particles is a composite plating film applied to a bearing main body member,
A sliding bearing having a composite plating film, characterized in that the average particle diameter of the inorganic particles is 1.5 μm or less, and the surface roughness of the composite plating film is Rz 4 μm or less. 2. The sliding bearing having a composite plating film according to claim 1, wherein the lead alloy contains one or more of Sn, In, Sb, Cu, and Zn in a total amount of 2 to 30% by weight. . 3. The bearing according to claim 1 or 2, which is formed as a laminate of a steel backing metal, a bearing copper alloy layer provided on the backing metal, and a composite plating film provided on the copper alloy layer. A sliding bearing having the composite plating film described above. 4. The bearing according to claim 1 or 2, which is formed as a laminate of a steel backing metal, an aluminum alloy layer for a bearing provided on the backing metal, and a composite plating film provided on the aluminum alloy layer. A sliding bearing having the composite plating film described above. 5. A layer having a thickness of 0.5 to 5 μm is provided between the composite plating film and the alloy layer that is the lower layer of the composite plating film.
There is an intermediate plating layer of N.
i, Ni alloy, Co, Co alloy, Fe, Fe alloy, Cu
5. The sliding bearing having a composite plating film according to claim 3 or 4, wherein the sliding bearing is made of one metal selected from the group consisting of , Cu alloy, Ag, and Ag alloy. 6. A bonding metal layer is present between the back metal and the alloy layer for bonding both layers, and the bonding metal layer is made of Ni, Ni alloy, Cu, Cu alloy, Al, and Al alloy. A sliding bearing having a composite plating film according to any one of claims 3, 4 and 5, which is made of any one metal selected from the group consisting of: