JPH04202640A - Overlay alloy for sliding bearing - Google Patents

Abstract

PURPOSE:To obtain an overlay alloy for a sliding bearing having superior corrosion and fatigue resistances by specifying the kinds and contents of the alloying components of a Pb alloy. CONSTITUTION:An overlay alloy consisting of 2-12wt.% Sn, >3-10wt.% In, >1-15wt.% one or more among Sb, Mn, Bi and Ag and the balance Pb with impurities is formed on a lining by electroplating, PVD such as sputtering or other method. Since this overlay alloy has superior corrosion and fatigue resistances, it is suitable for use as a sliding bearing for an internal-combustion engine.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an overlay alloy for a plain bearing, and more specifically, a plain bearing for an internal combustion engine, particularly a plain bearing that slides on a crankshaft or the like. The present invention relates to an overlay alloy mainly composed of Pb, which has excellent corrosion resistance and fatigue resistance in bearings.

[Prior art] Sliding bearings for internal combustion engines include cylindrical bushings, half metals, barrels,
There are thrust bearings, etc., and the parts that make up these are a backing metal usually made of a steel plate, a plain bearing alloy called a lining, which is bonded to the backing metal, and an overlay bonded to the lining.

Overlay alloys are soft alloys whose main components are lead or lead and tin, and their properties are improved by modifying the added components.

According to Japanese Patent Publication No. 39-22498, a lining made of a copper-lead alloy contains 2 to 10% of In, and optionally added components of Cub, 1 to 3%, and TeO, 001 to 0.25.
%, 0.5% or less of Ag, 0.5% or less of Sb, and a sliding bearing in which an overlay alloy is bonded, the balance being Pb, is known. According to the explanation in this specification,
In, Cu, and Te have the purpose of improving the corrosion resistance of cast alloys.

Furthermore, according to Japanese Patent Application Laid-Open No. 61-266544, I
An overlay alloy containing 1 to 10% of n, 0.1 to 6% of Cu, and 8% or less of Sn as an optionally added component, with the balance being Pb is known. According to the explanation in this specification, Cu has the effect of refining the alloy surface layer and retarding the diffusion of In into the base alloy, and as a result of these effects, corrosion resistance and fatigue resistance are improved. In improves corrosion resistance, and Sn
significantly improves corrosion resistance under interaction with In.

Next, Japanese Patent Application Laid-Open No. 59-20544 filed by the present applicant
According to Publication No. 2, In and/or "15% S02 to 10% over M210, Cu.

One or more of Sb, Mn, Ni, Ca, Bi, Ba 0.0
Overlay alloys consisting of 5-5% are known. According to the explanation in this specification, In and 1° C. mainly improve corrosion resistance, and Cu and the like form intermetallic compounds and mainly improve fatigue resistance.

In recent years, the operating conditions of internal combustion engines have become increasingly high temperatures and high loads, and the service life has become longer, so the performance required of overlays has become increasingly sophisticated. For example, as internal combustion engines have increased in speed and output in recent years, the oil temperature near the sliding surfaces has increased to 130-180°C.
Since the temperature can reach temperatures as high as ℃, problems of strength reduction and fatigue occur at high temperatures.

Furthermore, in internal combustion engines, soot (carbon particles), oil,
There is a problem of corrosion due to reaction products of components in the fuel mixed into the engine oil and coming into contact with the overlay. The reaction products are S04, fatty acids, halides (Cβ,
Br (compounds such as Br), NO, -.

The problems of additive components of overlays used under the conditions described above will be discussed.

Under high temperature conditions, Sn in the overlay alloy diffuses in the direction of the Ni plating, causing Sn to be depleted in the overlay, resulting in a decrease in its corrosion resistance and fatigue resistance. Furthermore, under the above-mentioned high temperature conditions, the In phase in the overlay melts, leading to peeling and baking of the overlay.

Additionally, Cu and In are added to improve the performance of Pb-5n based overlays, but since In is easily attacked by halides, and Cu forms compounds with 5Q4-, No, -, Corrosive wear of the overlay occurs. Furthermore, if a large amount of In is contained, there is a disadvantage that the melting point decreases.

Furthermore, if too much Cu is contained, fatigue resistance and conformability deteriorate, so there is a limit to the amount added (5% or less).If too much Sn is added, it will diffuse into the Ni plating interface. This leads to an enlargement of the compound layer and, like In, a decrease in the melting point.

[Problems to be Solved by the Invention] Cu, which is added to the overlay alloy of JP-A-59-20544, also reacts with Ni or diffuses into the lining under high-temperature usage conditions when added together with Sn.
Scarcity problems occur in overlays. For this reason, this known overlay cannot exhibit sufficient fatigue resistance under modern internal combustion engine usage conditions. Furthermore, the simultaneous addition of In and Sn to this known overlay significantly lowers the melting point or solidus of the alloy. For this reason, the above-mentioned diffusion of Sn and Cu occurs very easily. Additionally, overlay life shortening occurs due to Cu dissolution.

Since the overlay known from JP-A-61-266544 contains Cu and In as essential components, the phenomena already described regarding these components occur.

The overlay of Special Publication No. 39-22498 was published in 1960.
It was the subject of an application claiming priority in 1999, at a time when the use of internal combustion engines was much more relaxed than it is today.

For example, the specification of this application does not mention the use of Ni plating (on the contrary, it is considered that In in the overlay is diffused into the lining, and Cu in the lining is actively diffused into the overlay). Ni plating is used in the above two Japanese Patent Application Laid-open Publications (Kokai), which are newer than this application, but this is because the conditions for using internal combustion engines at the time of these applications were that in 1960, the talent was much more advanced. This reflects that he has become more sensitive.

As a result of the above studies, it has become clear that the overlays that have been known so far do not meet the usage conditions of modern internal combustion engines.

[Means and Effects for Solving the Problems] The present inventors investigated means for fundamentally improving the corrosion resistance and fatigue resistance of overlays, and as a result, they arrived at an overlay alloy having the following composition.

That is, by weight, more than In3 and less than 10%, Sn2~
The overlay alloy contains at least one of Sb, Mn, Bi, and Ag in an amount of more than 1 and less than 15%, and the remainder substantially consists of Pb and impurities.

The present invention will be explained in detail below.

Pb is the main component of the alloy of the present invention, and exhibits conformability, which is the basic performance required for overlays.

Sn improves corrosion resistance and fatigue resistance. If the content is less than 2%, there is no effect, and if it exceeds 12%, the compatibility is lowered and the melting point is lowered. The preferable Sn content is 4 to 8.
%.

In addition to exhibiting conformability, In dissolves in Pb, greatly increasing corrosion resistance and slightly increasing fatigue resistance. If the In content is less than 3%, there is no effect of improving corrosion resistance;
%, the melting point becomes low and performance at high temperatures, particularly wear resistance, deteriorates, and corrosion resistance against corrosive media such as halides deteriorates. The preferred content of In is 5 to 9%.

Any one or more of Sb, Mn, Bi, and Ag (hereinafter sometimes collectively referred to as "Sb etc.") is In-5b
, In-Mn, In-Ag, and other intermetallic compounds are formed and precipitated to maintain wear resistance and inhibit the growth of crystal grains at high temperatures, thereby preventing deterioration of strength and fatigue resistance. If the amount of these sb added is less than 1%, it acts only as a mere impurity, whereas if it exceeds 15%, Pb-I
The softness of the n solid solution is inhibited and the compatibility is reduced. s
The preferable addition amount of b is 1.5 to 7.5%.

Components other than those mentioned above are impurities. Typical impurities include Cu, Fe, Sn, and Zn.

It is preferable that the total amount of these impurities or each individual amount is 0.2% or less. In particular, Cu oils the overlay.
It has the disadvantage of being easily attacked by fuel reaction products, making it unsuitable as an additive element in overlays for high-load, high-speed internal combustion engines.

The overlay of the present invention is manufactured by PVD, such as casting, electroplating, or sputtering.

However, since the crystal grains become coarse in the casting method,
Preferably, it is produced by electroplating or PVD. In the PVD method, a desired component can be obtained in one step using targets for each component. It is also possible to perform a combination of PVD and electroplating; in this case, components other than In are laminated on the lining by PVD, In is laminated by electroplating, and then a layer is formed between these layers. Annealing can be performed to cause diffusion.

Electroplating is preferred from the viewpoint of cost during mass production.

The thickness of the overlay according to the present invention is determined by the usage conditions of the bearing, and is not particularly limited, but - as an example, from 1 to 30 μm.
It is m.

The overall structure of the sliding bearing using the overlay according to the present invention also depends on the usage conditions of the bearing and is not particularly limited.
Considering the operating conditions of modern internal combustion engines, it is preferable to provide an intermediate layer of i, Cu, Zn, etc. in order to prevent the diffusion of Sn and In in the case of a Cu-based lining, but it is not necessarily necessary in the case of an aluminum-based lining. May be omitted. The material, size, shape, etc. of the lining are not limited at all and are determined solely by the operating conditions of the internal combustion engine.

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

[Example] An overlay having the composition shown in Table 1 was coated with Cu via Ni plating.
Formed on the system lining by plating. The plating method will be explained below.

After Ni plating, washing with water is performed, and then the following plating layer is laminated on the Ni plating.

Pb-sb plating + In plating + Sn plating ■Pb-s
b plating (thickness 14 μm) Plating bath composition is lead sulfate (as lead ion concentration) 50 to 200 g/42 antimony sulfate (antimony ion).

(as concentration) 0.25-5 g/g.

Hydrofluoric acid 20-120g/ρ Additives (hydroquinone, etc.) 1-5g/ρ Plating conditions Liquid temperature 5-50℃ Current density 2,0-6,0 A/dm
■Water washing■In plating (thickness 1 μm) Sulfamic acid plating bath Indium sulfamate 40-210 g/β Sulfamic acid 10-60 g/β NaCl2゜15-100 g/ρ Glucose 7 2-2 5 g/
(f Triethanolamine 1 to 5 g/x Sodium sulfamate 70 to 320 g/jl! Liquid temperature 10 to 50°C Current density 1 to 10 A/dm' H 3.8 or less ■ Hot water washing ■ Sn plating Sodium stannate 100 g/ l ~150 g/12 Sodium hydroxide 5~50 g/42 Liquid temperature 60~85℃ Current density 0.6~3A/dm" Voltage 4~6V ■ Annealing 100~2oo℃ (In and sn Pb-sb
Diffusion into the plating layer) Corrosion resistance evaluation of the sliding bearing test piece produced by the above method was performed by preliminary heat treatment by the following method, and then carried out by a Soda type dynamic load tester (using the following oil).

Preliminary heat treatment 180"C x 200 hours Heating medium: 10W-30 oil (contains 3% inorganic acid and 3% organic acid. Test piece is immersed and heated) The test results are shown in Table 1.

(The following is a blank space) In Table 1, samples 12.14 to 18 do not contain sb and have poor corrosion resistance. This is considered to be because the strength of the sb-free test piece subjected to dynamic load decreased, promoting corrosion. Next, it can be seen that the reason why the corrosion resistance of sample 13.19 is poor is because it does not contain sb and In, but contains Cu. In contrast, the test piece of the present invention shows good corrosion resistance.

Next, after subjecting the above-mentioned test piece to the above-mentioned preliminary heat treatment, the following corrosion resistance tests (1) and (2) were carried out.
I did it.

1. Corrosion resistance test (1) 4I2 diesel engine test rotation speed x load: 4000 rpm x ful 1 oil
Temperature: 120°C Oil change every 210 Ohr bearing Width: 30% width narrowing 2, Corrosion resistance test (1) 2I2 leaded specification gasoline engine 7300 rpm x w, o, t.

Oil: 10w-30 Oil temperature: 135°C The test results of corrosion resistance test (1) and corrosion resistance (2) are shown in FIG. 1 and FIG. 2, respectively. From these results, it is clear that the test piece of the present invention has excellent corrosion resistance.

In addition, fatigue tests were conducted on several bearing test pieces using the following method, and the fatigue areas were measured.

Fatigue tester surface pressure: 800 kg/cm" oil near, 5w-30 oil temperature: 120°C The test results are shown in Figure 3. From this figure, it is clear that the fatigue resistance of the test piece of the present invention is excellent.

[Effects of the Invention] As explained above, the overlay alloy for a sliding bearing of the present invention has excellent corrosion resistance and fatigue resistance, and therefore has suitable performance as a sliding bearing for a recent internal combustion engine.

[Brief explanation of the drawing]

Figures 1 and 2 are graphs showing the results of the corrosion resistance test; FIG. 3 is a graph showing the results of the fatigue test. Patent applicant: Taiho Kogyo Co., Ltd.

Claims (1)

[Claims] 1. By weight, more than In3 and less than 10%, Sn2-12%
, Sb, Mn, Bi and Ag in an amount of more than 1 and 15% or less, with the remainder consisting essentially of Pb and impurities.