JPS6220915A - Plain bearing - Google Patents

Abstract

PURPOSE:To make improvements in anticorrosiveness, abrasion resistance and fatigue strength, by forming an overlay stratum, containing tin 15-30% plus iridium 0.1-10.0%, and consisting of lead in the rest in substance or containing copper 1.0-7% in this lead, on a surface of the base body. CONSTITUTION:An aluminum alloyed layer 2 is doubly layered on a halved or cylindrical back metal 1 and furthermore a nickel plating layer 3 and an overlay stratum 4 are formed on it. Tin content, which improves anticorrosionness and abrasion resistance in lead contained in this overlay stratum 4, is increased to a range of 15-30%, adding an iridium of 0.1-10.0% strongly holding a lubricating oil film, and the rest is formed with the lead. In addition, when copper for improving fatiguelessness and abrasion resistance is added, it should be set to a range of 1.0-7.0%. Therefore, anticorrosiveness, the abrasion resistance and fatigue strength are all sharply improvable.

Description

[Detailed Description of the Invention] <Object of the Invention> Industrial Field of Application The present invention relates to plain bearings, and more specifically, due to the rise in temperature of lubricating oil due to the increase in output of internal combustion engines in recent years and the oxidation of lubricating oil at high temperatures, etc. This invention relates to a plain bearing that exhibits sufficient performance under conditions such as an increase in the amount of wired acid generated.

Conventional technology Conventionally, the bearing metal used in internal combustion engines has a half-shaped or cylindrical steel backing metal, and a copper-based or aluminum-based bearing base metal is layered on top of this. Although these copper-lead bearing alloys, bronze bearing alloys, and aluminum bearing alloys developed as high-load bearings have poor load-bearing properties, they have other characteristics necessary for bearing base metals, such as seizure resistance and embedding resistance. There are problems with embeddability, conformability, etc., and in order to solve these problems, it is necessary to overlay a metal component with embeddability and conformability on the bearing base metal. For example, in conventional automobile bearings, a copper or aluminum alloy is adhered as an intermediate layer on a back metal by sintering, casting, pressure bonding, etc., and an overlay layer with a thickness of 10 to 30 μm is further applied on top of this. bearings are used. This overlay has the effect of improving the wear resistance, conformability, and foreign matter embedding property of the bearing. Conventionally, the composition of the overlay has been Pb-3n system, Pb-Sn-Sb system, Pb-
3n-Cu system, Pb-3n-In system, etc. are known, and in particular,
Lead 85~ disclosed by U.S. Patent No. 2,605,149
Pb-3n-Cu with 90%, 8-12% tin, 2-3% copper
System overlays are the most commonly used. The lead in this overlay improves the compatibility between the bearing and the journal and the embedding of foreign matter in the lubricating oil, the tin improves corrosion resistance, and the copper plays a role in improving fatigue resistance.

However, in recent years, as the output of internal combustion engines increases and the temperature of the lubricating oil increases, the overlay tends to soften and wear resistance deteriorates.Furthermore, high temperatures accelerate the oxidation of the lubricating oil and cause organic acids to oxidize. There is a need for the development of improved overlays due to the problem of the formation of corrosive products such as, which corrode the overlays.

Problems to be Solved by the Invention The present invention aims to solve these problems, and specifically improves corrosion resistance and wear resistance by increasing the tin content of the conventional Pb-Sn-Cu based overlay. The object of the present invention is to provide an overlay with improved fatigue resistance by adding indium to the overlay.

<Structure of the Invention> Means for Solving the Problems and Their Effects The present invention provides a flat bearing for use in an internal combustion engine that contains 15 to 30% tin and 0.1 to 10.0% indium on the surface of its base. , an overlay layer in which the balance is essentially lead, or an overlay layer in which 1.0 to 7.0% copper is further added.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIGS. 1(a) and 1(b) are a perspective view and a sectional view taken along arrow A-A, showing an example of a plain bearing of the present invention.

In FIG. 1, reference numeral 1 indicates a backing metal, 2 a copper or aluminum alloy layer, 3 a nickel plating area, and 4 an overlay layer.

Tin in conventional overlays is in solid solution with lead, and exists in some cases as a matrix and in this matrix as a copper-tin intermetallic compound; It forms tin crystals and is scattered throughout the matrix. During operation of the internal combustion engine, this copper-tin intermetallic compound combines with the tin solidly dissolved in the fine tin crystals or matrix, and gradually transforms into a steel-tin intermetallic compound with a high tin content. . As a result, the amount of solid solution tin in the matrix and interspersed tin in the matrix is reduced, reducing the corrosion and abrasion resistance of the overlay.

Furthermore, tin in the overlay that is present near the nickel plating layer forms an intermetallic compound with the nickel and gradually migrates into the nickel layer. Similarly to the aforementioned copper-tin intermetallic compound, the tin content in the overlay near the nickel plating layer gradually changes to a tin-nickel intermetallic compound with a higher tin content during operation of the internal combustion engine. The wear resistance and corrosion resistance in this area are significantly reduced.

Based on the observation of the behavior of tin as described above, the present invention increases the tin content in the overlay to 15 to 30%, and further adds 0.1 to 10.0% of indium. This solves the problems of wear resistance and corrosion resistance, and further improves fatigue resistance.

Next, the role of each element in the overlay of the present invention and the addition m
To explain, tin improves the corrosion resistance and wear resistance of lead, but as the output of internal combustion engines increases as it does today, if the content is less than 15%, the tin scattered in the matrix will increase due to the reasons mentioned above. The corrosion resistance and wear resistance of the overlay are greatly reduced. Furthermore, the tin content m is 3
If it exceeds 0%, the overlay will soften at high temperatures, resulting in poor fatigue resistance and wear resistance. Therefore, the tin content is 15
~30% is optimal.

Furthermore, indium is present diffusely in the lead-tin matrix in the overlay and is several times more effective than tin in improving the corrosion resistance of the overlay. Furthermore, in order to improve the efficiency of modern internal combustion engines, there is a tendency to reduce the gap between the bearing and the seat and to increase the rotational speed. Therefore, there is an increasing chance that the overlay of the bearing will come into contact with the journal and wear out. The indium in the new overlay has the effect of strongly retaining the lubricating oil film in such cases and reducing overlay wear caused by metal contact.

In addition, copper is added to improve the fatigue and wear resistance of the overlay, but the best performance is achieved when the content is around 1.0 to 7.0 layers, and outside this range, the fatigue resistance decreases.

Example This will be further explained below using examples.

Example 1 First, a bearing base metal is degreased and pickled in the same manner as in general electroplating, and then nickel plated to a thickness of 1.0 to 2.0 μm. In the case of copper-based bearing alloys, the role of this nickel plating is to prevent tin in the overlay from diffusing into the intermediate layer of copper alloy during operation of an internal combustion engine, thereby preventing the corrosion resistance of the overlay from deteriorating. An overlay is electroplated onto this nickel plating in a plating bath and current density of bath composition (A) below.

Current density 1.0-3. OA/dm2 Next, indium plating is performed on this overlay plating at the following bath composition (B) and current density.

Current density 1.0-3. OA/dm2 A flat bearing after indium plating consists of four decoys: one or two overlays of backing metal/copper alloy and one indium layer. When the flat bearing consisting of these four layers is heated at 100 to 150°C for 2 hours, the indium plating layer will melt into the base. , and a new overlay category with the following composition is obtained.

Note that the above components can be freely changed within the range by adjusting the overlay and indium plating thickness, that is, current density and plating time.

Example 2゜ As in Example 1, nickel plating is applied to the bearing base metal.

Next, overlay plating shown by 4 in FIG. 1(b) is performed on this plating using the bath composition (C) and current density shown below.

Current density 1.0-3. OA/dm2 Next, on this overlay plating, indium plating was performed on 4 using the bath composition (B) and current density of Example 1.
Heating at ~150° C. for 2 hours and interdiffusion with the underlying overlay layer yields a new overlay layer with the following composition:

The components of the overlay can be freely changed within the range by adjusting the current density and plating time as in Example 1.

To measure the corrosion resistance of the new overlay described in detail above, 1% oleic acid was added as a corrosive to SAE 10 engine oil without inhibitors,
It was immersed for 0 hours and its corrosion weight loss was measured. As a result, the corrosion resistance of the new overlay was approximately five times that of the conventional overlay.

Furthermore, in order to measure the wear resistance of the new overlay, we used an Underwood test S machine with a load of 560 kg/I]2 and a rotation speed of 35.
0Orpm, overlay thickness 0.020mm, bearing back temperature 175℃, lubricant SAE 20W-40, test time 1
00 hours, and the weight loss of the bearing before and after the test was measured. As a result, the weight loss of the new overlay was very small compared to the conventional product.

Furthermore, regarding fatigue resistance, a comparative test was conducted under the same conditions as the above-mentioned wear resistance test until fatigue failure occurred in the overlay, and the result was that it was equal to or better than 120~
The durability was 160 hours.

<Effects of the Invention> As explained in detail above, by increasing the tin content of the conventional overlay layer and further adding indium to this, corrosion resistance, wear resistance, and fatigue strength have been greatly improved. increased output of internal combustion engines, increased temperature of lubricating oil,
In addition, a plain bearing with a new overlay region that can sufficiently cope with the increase in organic acids generated by oxidation of lubricating oil at high temperatures was obtained.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a perspective view showing an example of the flat bearing of the present invention and a cross-sectional view taken along arrow A-A. Code 1... Back metal 2... Copper or aluminum alloy layer 3...
...Nickel plating layer 4...Overlay layer

Claims (1)

[Claims] 1) Tin 15 is added to the surface of the base of a plain bearing used in an internal combustion engine.
30% of indium and 0.1 to 10.0% of indium, with the remainder being substantially lead. 2) Tin 15 is added to the surface of the base of plain bearings used in internal combustion engines.
~30%, copper 1.0-7.0% and indium 0.1
10.0% of lead, and the remainder is formed of an overlay layer consisting essentially of lead.