JPH04236297A - Anti-seizing member - Google Patents

Abstract

PURPOSE:To provide an anti-seizing sliding member having an improved anti- seizing property and exhibiting a stable bearing performance for the high load operation of the recent automotive engines. CONSTITUTION:Since a hard thin film layer having a low friction coefficient and a high hardness is formed on a Pb-Sn alloy overlay layer formed on the sliding surface of a matrix, the hard thin film layer divided by a sliding action with the other shaft is sunk in the overlay layer to prevent the abrasion of the overlay plated layer and increase the seizing resistance, consequently permitting to provide the anti-seizing sliding member exhibiting an excellently durable and stable bearing performance even on a high load operation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seizure-resistant sliding member.

0002

2. Description of the Related Art An overlay is a soft metal film with a thickness of about 10 microns formed on the surface of a bearing alloy, and is usually formed by electroplating an alloy mainly composed of Pb and Sn. Additionally, nickel plating (referred to as a nickel barrier layer) with a thickness of several microns is often applied between the overlay and the bearing alloy to improve corrosion resistance.

Bearings that require an overlay plating layer on the surface are those made of a low Sn-Al alloy, such as JIS
H5402 AJ-1 (10%Sn-0.75Cu
-0.5Ni-AlBal), JIS H5402
AJ-2 (6% Sn-2.5Cu-1.0Ni-A
lBal) etc., or Kelmet (23%Pb-3%
There are copper-lead alloys such as Sn-CuBal).

On the other hand, bearings that do not require overlay plating are SAE738 (20% Sn-0.5Si).
-1.0Cu-0.1Ti-AlBal),
It is made of a high Sn-Al alloy. In addition, it has been known for some time that P in Al-Sn alloys is present regardless of the Sn content.
B is added to improve lubricity and provide anti-seizure properties.

Furthermore, in order to cope with high-load operation, Al
- A bearing in which coarse Si is dispersed and precipitated in a Si-based alloy has been proposed, and this bearing has cutting force due to hard Si precipitates, and the uneven surface of the mating shaft is shaved off to make it flat. and improve bearing performance.

[0006]

[Problems to be Solved by the Invention] Recent automobile engines have become smaller, more fuel efficient, and have higher output, and as a result, the load on the bearings has increased, and the temperature of the lubricating oil has increased. The conditions under which bearings are used are becoming increasingly severe.

[0007] For this reason, conventional multi-component or Al-based bearing alloys in which overlay plating is applied to the surface suffer from fatigue and seizure phenomena due to the high temperature of the lubricated surface, making them unusable. Therefore, recently there has been a demand for bearing alloys that do not have surface layers such as overlay plating, but even this type of bearing alloys cannot necessarily demonstrate stable performance under the harsh conditions described above. It is.

For example, a high Sn--Al alloy that does not require overlay plating contains approximately 20% more Sn, which results in low hardness and weakens the Al matrix, making it unable to withstand high loads.

[0009]Al-Sn alloys that add Pb to improve lubricity were developed for the purpose of providing lubricity during normal operation, so they do not have sufficient durability under high-load operating conditions. It has the disadvantage of not exhibiting fatigue properties.

Furthermore, coarse Si is present in the Al-Si alloy.
If the mating shaft is made of a material other than graphite cast iron, the shaft surface will be irregularly scraped by the coarse precipitates during high-load operation, causing seizure and serious problems.

The present invention was made to solve the problem that conventional bearing alloys do not exhibit sufficient fatigue resistance or seizure resistance for the high-load operation of modern automobile engines. Therefore, it is an object of the present invention to provide a seizure-resistant sliding member that suppresses wear of the conventional Pb-Sn based overlay plating layer, improves wear resistance and seizure resistance, and exhibits stable bearing performance. .

0012

[Means for Solving the Problems] The seizure-resistant sliding member of the present invention includes a nickel barrier layer formed on the surface of the sliding portion of a base material, and a Pb-Sn layer formed on the nickel barrier layer.
The gist of the present invention is to consist of an overlay layer made of a base alloy, and a hard thin film layer formed on the overlay layer and having a thickness of 0.1 to less than 3 μm.

The bearing alloy that is the base material of the present invention is Al-S.
In addition to non-ferrous bearing alloys such as n-based, Pb-Cu-based, and Sn-Sb-Cu-based bearing alloys, iron-based bearing alloys may also be used.

The thickness of the nickel barrier layer and overlay layer is the same as that conventionally used, and is a general thickness, and can be formed by conventionally known plating means such as electroplating or electroless plating. It is formed.

The hard thin film layer formed on the overlay layer is an inorganic hard film formed by a CVD method (chemical vapor deposition method) or a PVD method (physical vapor deposition method).
Nitride or carbide such as iN, TiC, or BN, or a diamond-like carbon film, which is known as a relatively hard carbonaceous film, can be used. These hard thin film layers need to have a friction coefficient of 0.2 or less and a hardness of Hv2000 or more in order to impart sufficient lubricity and wear resistance to the bearing.

[0016] The hard thin film forming method uses Pb in the overlay layer.
-Because it is formed on a low melting point material called Sn alloy,
The processing temperature is required to be 200° C. or lower, and suitable methods include, for example, ion plating and ion mixing.

[0017] The thickness of the hard thin film layer to be formed is from 0.1 to
It needs to be less than 3 μm. The thickness of the hard thin film layer is 0.
If the thickness of the hard thin film layer is less than 1 μm, the amount of hard particles will be insufficient and it will not be possible to impart sufficient seizure resistance to the bearing. This is because the thin film layer peels off and is not useful for improving the performance of the bearing.

[0018]

[Function] The seizure-resistant sliding member of the present invention has a hard thin film layer formed on the overlay layer made of Pb-Sn alloy formed on the sliding surface of the base material, so that The sliding causes the hard thin film layer to break and collapse into the overlay layer. This state will be explained with reference to a micrograph showing the grain structure of the sliding surface in FIG. 11 and a schematic enlarged sectional view of the sliding portion in FIG. 10.

In the micrograph of FIG. 11, the black part is the hard thin film layer, and the white part is the overlay plating layer. As is clear from the photograph, the hard thin film layer was cut due to the high surface pressure of the other object, and a portion remained. This cut and remaining hard thin film layer is shown in Figure 10.
As shown in , the surface of the soft overlay plating layer is depressed.

[0020] The hard thin film layer dispersed and recessed in the overlay layer has a low coefficient of friction and high hardness, so it suppresses wear of the overlay plating layer and increases the seizure load. As a result, it is possible to obtain a seizure-resistant sliding member that exhibits stable bearing performance even during high-load operation.

[0021]

[Example] Examples of the present invention will be explained together with comparative examples to clarify the effects of the present invention. (Example 1) As invention example 1, JIS H4502
Al-Sn alloy equivalent to AJ-1 (10.2%Sn-0
．． 72% Cu-0.55Ni-AlBal) was prepared,
As shown in the perspective view of FIG. 2, a seizure test plate 12 was fabricated with a ring-shaped sliding portion 10 provided on its surface. This baking test plate 1
As shown in the cross-sectional view of the sliding part 10 in FIG.
4, and a Pb-Sn-Cu alloy (9%Sn
An overlay plating layer 16 of 20 .mu.m thick is formed, and a hard thin film layer 18 of 0.2 .mu.m thick and 0.2 .mu.m thick is formed of a diamond-like carbon film by ion plating. 8μm, 1μm
, 1.5 μm, 2 μm, and 3 μm thick.

The apparatus used for ion plating was a diamond-like carbon coating apparatus manufactured by Nanotech, and an outline of the apparatus is shown in FIG. In FIG. 4, the source gas 20 is heated and ionized by the filament 22, accelerated by the anode 24, and strongly collides with the substrate 26 to which a negative voltage is applied, thereby forming a hard thin film layer.

Next, as invention example 2, copper lead alloy (23%
Pb-3%Sn-CuBal) was prepared and processed into a baking test plate 12 having the same shape as Invention Example 1. This baking test plate 1
As shown in the cross-sectional view of the sliding part 10 in FIG.
4 and a Pb-Sn alloy (10%Sn-P
An overlay plating layer 16 is formed with a thickness of 20 μm, and a hard thin film layer 18 of a diamond-like carbon film is formed on the overlay plating layer 16 with a thickness of 0.2 μm, 0.5 μm, 1 μm, 2 μm, It was formed with a thickness of 3 μm.

Note that FIG. 5 shows a schematic configuration diagram of the apparatus used for ion mixing. In FIG. 5, the vacuum chamber 2
The silicone oil in the oil reservoir 30 attached to the substrate 8 is heated by the heater 32, and when the gate valve 34 is opened, it becomes silicone oil vapor 36 and is released onto the substrate 38.
Deposit on. On the other hand, when the substrate 38 is irradiated with Ar ions ionized by an ion beam generator (not shown) as an ion beam 40, a diamond-like carbon film is formed on the substrate 38. In invention example 2, silicone oil was heated at 150°C, and Ar+ ions of 1Mev were heated 1×
1017 pieces/cm2 were irradiated.

When the friction coefficients of the hard thin film layers obtained in Inventive Examples 1 and 2 were measured, the results shown in FIG. 6 were obtained.

Next, as Comparative Examples 3 to 10, seizure test plates 12 having the same shape as the invention example were prepared using the following alloys. In Comparative Example 3, the base material, nickel barrier layer, and overlay layer were exactly the same as those in Invention Example 1, but no hard thin film layer was formed. In Comparative Example 4, the base material, nickel barrier layer, and overlay layer were exactly the same as those in Invention Example 2, but no hard thin film layer was formed. In Comparative Example 5, the base material was the same as Invention Example 1, but the hard thin film layer of Invention Example 2 was formed without the nickel barrier layer and overlay layer. In Comparative Example 6, the base material was the same as Invention Example 1, but a nickel barrier layer, an overlay layer, and a hard thin film layer were not formed. In Comparative Example 7, the base material was SAE780 (6%Sn-2%Si-1%Cu-0
．． 5Ni-0.1%Ti-AlBal) with no nickel barrier layer or overlay layer, and the hard thin film layer of Invention Example 2 was formed. In Comparative Example 8, the base material was SAE780 (6%
Sn-2%Si-1%Cu-0.5Ni-0.1%Ti
-AlBal) only. In Comparative Example 9, the base material is SAE
783 (20%Sn-0.5%Si-1%Cu-0.1
%Ti-AlBal), with no nickel barrier layer or overlay layer, and the hard thin film layer of Invention Example 2 was formed. In Comparative Example 10, the base material was SAE783 (20% Sn-0.
5%Si-1%Cu-0.1%Ti-AlBal) only.

Next, a cylindrical rotating body 42 made of material S45C and shown in FIG. Invention Example 1 obtained above by contacting and rotating
~2, Regarding the seizure test plates of Comparative Examples 3 to 10, sliding part 1
0 burn-in test was conducted.

The rotational and load conditions for this seizure test were as shown below; the product was rotated at high speed in oil, the load was gradually increased, and the seizure resistance was evaluated based on the seizure load. Rotating body number of times
2000r. p. m. oil
JIS 5W-30
(Temperature 100℃) Loading speed
25kgf/2min

002
9] The results of the seizure tests obtained are shown in FIG. 7 for Invention Examples 1 and 2, and in FIG. 8 for Comparative Examples 3 to 10, respectively. As is clear from FIG. 8, Comparative Examples 3 to 10
The seizure surface pressure was 150 to 380 kgf/cm2. On the other hand, as shown in FIG. 7, inventive examples 1 and 2,
550 to 72, except for those in which the hard thin film layer was 3 μm.
It was confirmed that the seizure resistance was significantly improved by forming a hard thin film layer with a thickness of 0 kgf/cm2 and a thickness of less than 0.2 to 0.3 μ on the overlay plating layer.

[0030] For those with a hard thin film layer of 3 μm or more, it is thought that this is because the hard thin film layer peels off before it sinks into the overlay layer, and there is no hard enough thin film left to improve the seizure resistance. It will be done. Also, Comparative Examples 5 and 7
, 9, which formed a similar hard thin film layer, had a low baking surface pressure because it lacked a nickel barrier layer and overlay layer and the base material had high hardness, and the hard thin film layer did not cave in. This is because most of it has peeled off.

(Example 2) The hard thin film layer of Invention Example 1 was 0.
2 μm and 2 μm, the hard thin film layer of invention example 2 is 0.2
Bearings of μm and 2 μm, and those having the same configuration as Comparative Examples 3 to 8, were formed as actual bearings, and an Underwood fatigue test was conducted to check the final bearing performance.

In this test, the bearing was fixed to the connecting rod housing, an eccentric load was applied to the shaft, and a durability test was conducted under the following conditions, almost the same as the conditions of an actual engine. It is evaluated based on the length of time it is maintained. Note that the upper limit of the test time was 500 hours. The results obtained are shown in FIG.

As is clear from FIG. 9, the durability of Comparative Examples 3 to 8 was 200 to 300 hours. In contrast, the examples of the present invention have a durability time of 450 to 480 hours,
It has been found that the present invention also provides excellent results in terms of durability.

[0034]

Effects of the Invention The seizure-resistant sliding member of the present invention has a hard thin film layer formed on the overlay layer made of Pb-Sn alloy formed on the sliding surface of the base material. Due to the sliding, the hard thin film layer is divided and depressed into the overlay layer, and the hard thin film layer that is dispersed and depressed in the overlay layer in this way has a low coefficient of friction and high hardness.
Suppresses abrasion of the overlay plating layer and increases seizure load. As a result, it is possible to obtain a seizure-resistant sliding member that exhibits excellent durability and stable bearing performance even during high-load operation.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a sliding part.

FIG. 2 is a perspective view of a seizure test plate used in Examples.

FIG. 3 is a perspective view of a rotating body used in a seizure test.

FIG. 4 is a schematic configuration diagram of an ion plating apparatus.

FIG. 5 is a schematic configuration diagram of an ion mixing device.

FIG. 6 is a diagram showing measurement results of the friction coefficient of an example of the present invention.

FIG. 7 is a diagram showing the seizure surface pressure of the seizure test of the example of the present invention.

FIG. 8 is a diagram showing the seizure surface pressure in the seizure test of a comparative example.

FIG. 9 is a diagram showing durability time according to the Underwood fatigue test.

FIG. 10 is a schematic enlarged sectional view of a sliding part.

FIG. 11 is a micrograph showing the grain structure of the sliding surface.

[Explanation of symbols]

10 Sliding part 12 Seizure test plate 14 Nickel barrier layer 16 Overlay layer 18 Hard thin film layer 20 Raw material gas 22 Filament 24 Anode 26 Board 28 Vacuum chamber 36 Silicone oil vapor 38 Board 40 Ion beam 42 Rotating body

Claims (1)

[Claims] Claim 1: A nickel barrier layer formed on the surface of the sliding part of the base material, and a nickel barrier layer formed on the nickel barrier layer.
A seizing-resistant sliding member comprising an overlay layer made of a b-Sn alloy and a hard thin film layer formed on the overlay layer and having a thickness of 0.1 to less than 3 μm.