GB2415753A

GB2415753A - Sliding member

Info

Publication number: GB2415753A
Application number: GB0521504A
Authority: GB
Inventors: Satoshi Takayanagi; Masahito Fijita; Takayuki Shibayama
Original assignee: Daido Metal Co Ltd
Current assignee: Daido Metal Co Ltd
Priority date: 2003-04-17
Filing date: 2004-04-16
Publication date: 2006-01-04
Anticipated expiration: 2024-04-16
Also published as: WO2004092602A1; JPWO2004092602A1; JP4589229B2; DE112004000651T5; GB0521504D0; GB2415753B; DE112004000651B4

Abstract

A sliding member which has a substrate and a sliding layer (overlay), wherein the overlay (sliding layer) (4) comprises a base material of a metal selected from among Sn, Pb, Bi, In and Al or an alloy based on the metal and an amorphous carbon as an additive. The overlay (4) is formed by sputtering. Sn, Pb, Bi or In is excellent in non-seizure property due to its low adhesion to a mating material such as Fe. An amorphous carbon improve wear resistance and fatigue resistance due to its high hardness and also improve non-seizure property due to its low friction coefficient. Further, by the addition of an amorphous carbon, the above base material having finer crystal grains is formed, which results in the enhancement of the mechanical strength and further improvement of the wear resistance and fatigue resistance of the overlay (sliding layer).

Description

DESCRIPTION

SLIDING MEMBER

Technical Fleld The present invention relates to a sliding member having a sliding layer on a substrate.

Background Art

Conventionally, there is a sliding member such as a slide bearing for an engine in a vehicle, which has a sliding layer (overlay) provided on a substrate.

As this sliding layer, use of an Sn-based coat is widely known as disclosed in Japanese Unexamined Patent Publication No. S53-14614. Forming of an overlay [coat] by using a base material of soft metal such as a Pb-based coat 1S generally known as well as the Sn-based coat.

As well as Sn and Pb, soft metals such as In and Bi were conventionally used for sliding layers of many sliding members since they are very excellent in anti-seizure property due to their low adhesion to a mating material such as Fe.

However, these metals are poor in fatigue resistance since they are soft, and use of these was impossible in some high-pressure engines.

In order to solve these problems, for example, in Japanese [Jnexamined Patent Publication No. 2001-247995, lt has been proposed that the overlay is formed by adding a large amount of metal such as Cu that improves hardness and mechanical strength oftheSnbasedbasematerialtotheSn-basedmaterial. However, the Sn and Cu easily compose a hard and brittle compound, and growth of such a compound is easily promoted due to treat generated during driving of the engine. Such a hard and fragile compound easily damages a mating material and lowers anti-seizure property. Furthermore, the largely grown compound is easily dropped off, and fatigue breakage easily occurs from the drop-off portion, resulting in lowering in fatigue resistance.

In order to improve the wear resistance and fatigue resistance of the sliding layer, as disclosed in Japanese Unexamined Patent Publication No. H07-252693, in some cases, hard particles (for example, SiC, Si3N4) are added in Sn or an Sn-based alloy by means of a composite plating technique.

However, the hard particles to be added by means of the composite plating technique have large particle diameters of 0.1 through several micrometers, and the plating is wet plating, so that even dispersion of herd particles in the plating solution is difficult, and the distribution of hard particles frequently is not uniform in the overlay. In such a sliding layer, large hard particles and hard particles in the form of a large lump easily damage a mating material and lowers anti-seizure property.

On the other hand, a slide bearing to be used in a diesel engine in that a high load acts needs to have fatigue resistance.

To meet this need, conventionally, as a sliding layer of a diesel engine slide bearing, an Al-based coat 1S frequently used. This M-based coat is mace ofanAl-Sn alloy, wherein Alsupports loads and soft Sn shows compatibility and anti-seizure property.

Therefore, in this sliding layer made from an Al-Sn alloy, by increasing the Sn content, the anti-seizure property can be improved. However, lf soft Sn increases, the hardness of the sliding layer lowers, resulting In lowering in fatigue resistance. In these circumstances, although Sn is added with a limit of 20 percent by mass or less in a conventional Al-Sn alloy-made sliding layer, this is not sufficient in terms of anti-seizure property.

The invention was made in view of these circumstances, and an object thereof is to provide a sliding member including a sliding layer that uses any metal of Sn, Pb, Bi, In, and Al or an alloy based on the metal as a base material, which improves fatigue resistance, or, in particular, a sliding layer that uses an Al-Sn alloy as a base material of the sliding layer, which improves anti-seizure property without lowering in fatigue resistance.

Disclosure of the Invention

According to the invention, a sliding layer Is formed on a substrate, and the sliding layer made of a base material of any metal of Sn, Pb, Bi, In, and Al or an alloy based on the metal, and amorphous carbon is added to this base material.

The sliding layer can be formed by sputtering, ion plating, CVD, or the like as dry coating.

Among the metals to be used as the base material of the sliding layer, Sn, Pb, Bi, and In except for Al are very excellent in anti-seizure property due to their low adhesion to a mating material such as Fe.

When Al 1S used as the base material of the sliding layer, Alit made into an alloy with other soft metals such asSn, whereby ruralizing excellent ants-seizure property. Even when the a-idtion of Sn is increased, Al and SO become fine and high in strength by means of addition of amorphous carbon. Therefore, the problem of lowering in fatigue resistance does not occur, and a sliding layer being excellent in both fatigue resistance and anti-seizure property is obtained.

Amorphous carbon is high in hardness, so that It increases the mechanical strength and improves wear resistance and fatigue lO resistance. In addition, it also has a low coefficient of friction, and amorphous carbon also improves anti-seizure property. Furthermore, addition of amorphous carbon makes fine the crystallites of the base material of the sliding layer.

Accordingly, the mechanical strength of the sliding layer IS increased and the wear resistance and fatigue resistance can be further improved.

Herein, the crystallites are a base unit of particles and the base material containing the particles in the sliding layer.

Making the crystallites fine leads to fineness of the base material. As described later, the crystallizes can be confirmed by X-ray diffraction analysis and particles can be confirmed by structure observation with a scanning electron microscope.

As amorphous carbon, in particular, diamond-like carbon (hereinafter, referred to as DLC) IS preferable. DLC mentioned in this specification includes not only complete amorphous DLC but also DLC having fine crystallizes.

In this case, the crystallite diameter of the base material measured by Xray diffractlor- analysis is preferably 100 nanometers or less. When the crystallites of the base material ofthe sliding layer become fine to this level, as described above, the mechanical strength ls increased, and wear resistance and fatigue resistance are further improved.

Any one or more kinds of metals of Sn, Pb, Bi, Al, In, Cu.

Sb, Ag, and Cd can be added to the base material of the sliding layer. In this case, Sn, Pb, Bl, In, and Al are metals that can become the base material of the base side, and have a function of improving anti-seizure property, conformability, and corrosion resistance. Cu. Sb, Ag, and Cd have a function of improving the mechanical strength and hardness of the sliding layer.

When the metal to be added is any one or more kinds of metals of Sn, Pb, Bi, In, and Al, the contents of the metals to be added are preferably 20 percent by mass or less and the total contents of these metals to be added is preferably 30 percent by mass or less. However, when the base material on the base side is Sn or Al, Al and Sn are excluded from the metals to be added. If the contents of these metals to be added exceed 20 percent by mass or the total content of these exceeds 30 percent by mass, a tendency is shown In that the melting point of the sliding layer significantly lowers and the anti-seizure property lowers.

When the metal to be added is any one or more kinds of metals of Cu. Sb, Ag, and Cd, the contents of the metals to be added are preferably 5 percent by mass or less, and the total content of these metals to be added 1S preferably 10 percent by mass or less. These metals to be added easily form a hard and brittle compound in conjunction with the base material of the sliding layer. Therefore, if the contents of the metals to be added exceed 5 percent by mass or the total content of these exceeds lO percent by mass, the compound becomes large and easily drops off, so that fatigue breakage and wearing progresses from this point and tends to lower the fatigue resistance and wear resistance.

When Al is used as the base material of the sliding layer, it is preferable that Al is made into an alloy with Sn, and the contents thereof are 20 through 80 percent by mass of Al and 20 through 80 percent by mass of Sn, and amorphous carbon is added to the base material of this Al-Sn alloy. In this Al-Sn alloy, even when the Sn content is increased, the crystallites of Al and Sn become fine and increase the mechanical strength, so that there is no possibility of lowering in wear resistance, and a sliding layer excellent in wear resistance and anti-seizure property is obtained.

To the Al-Sn alloy that forms the sliding layer, any one or more metals of Si, Cu. Sb, In, and Ag can be added. In can improve the anti-seizure property, conformability, and corrosion resistance. Cu. Sb, and Ag increase the mechanical strength and hardness of the sliding layer. Si is a hard element and increases the hardness of the sliding layer and improves fatigue resistance. Si serves as a hard element and acts to scrape-off metals adhering to a mating material, so that it improves the antl-seizure property. These Sl, Cu. Sb, In, and Ag are added preferably in proportion of 5 percent by mass or less singly, and a total content of these metals to be added is preferably lO percent by mass or less.

Tf the contents of In and Ag exceed 5 percent by mass or the tot alcontent of these exceeds lO percept bypass, the melting point:E the sliding layer tends to significantly lower and anti-seizure property tends to lower. Cu. Sb, and Ag form a hard and fragile compound in conjunction with Al and Sn, and if the contents of these metals to be added exceed 5 percent by mass or the total content of these exceeds 10 percent by mass, the compound becomes large and easily drops off, so that fatigue and wearing tend to progress. Si hardly forms a compound in lO conjunction with Al and Sn, and if its content is increased, it becomes easy to drop off from the sliding layer.

The Al-Sn alloy is made fine by adding amorphous carbon.

The level of this fineness is preferably 1 micrometer or less as the particle diameter of Al or Sn. When the particle diameter is 1 micrometer or less, the effect of improving the fatigue resistance and anti-seizure property becomes more excellent.

The particle diameter is more preferably 0.05 micrometers or less. As the diameter of the particles becomes smaller than 0.05 micrometers, the crystallites are made finer and more excellent fatigue resistance is obtained.

The crystallite diameter can be set to 30 nanometers. If the crystallites diameter IS fine on this level, more excellent fatigue resistance can be obtained.

Herein, the mechanism for making fine the crystallites by adding amorphous carbon 1S described. Amorphous carbon arrests the growth of crystallizes and makes the crystallltes fine.

When the base material is made of a pure metal such as Sn, the fineness of the crystallites due to addition of amorphous carbon can be confirmed by means of X-ray diffraction analysis, however, the difference cannot be confirmed based on the existence of amorphous carbonic sectional structure observation with a scanning electron microscope.

When amorphous carbon is added to an Al-Sn alloy to form an overlay, amorphous carbon still arrests the growth of crystallltes of Al and Sn, and makes the crystallltes of Al and Sn fine. This can be confirmed by means of X-ray diffraction analysis as in the case of the description given above. When the sectional structure is observed when amorphous carbon is not added, Al and Sn can be observed in the form of separate phases, end when therelsa differenceln consent between AlandSn, either one with the smaller content can be observed as particles.

However, when amorphous carbon is added, Al and Sn crystallites aremade fine, end es a result, insectlonalstructure observation with a scanning electron microscope, it becomes very difficult to observe Al or Sn particles.

In the sliding layer formed by using any metal of Sn, Pb, Bi, In, and Al or an alloy based on the metal as a base material and adding amorphous carbon to this base material, the content of the amorphous carbon is preferably 0.1 through 8 percent by mass. When the content of amorphous carbon is 0.1 percent by mass or more, the crystallltes of the base material are sufficiently made fine and its hardness is also increased. When the consent is 8 percent by mass or less, the hardness is properly high and excellent antl-seizure property can be maintained without losing embeddability.

Ihe thickness of the sliding layer IS preferably 30 micrometers or less. When the thickness is 30 micrometers or Less, itis effective forinternalstress reduction of the sliding layer, and preferable ln terms of fatigue resistance.

Brlef Description of the Drawings

FIG. 1 is a schematic sectional view of a slide bearing according to an embodiment of the invention; FIG. 2 is a schematic sectional view showing crystallizes of an overlay; FIG. 3 is a diagram of overlay compositions used in experiments and experimental results showing the effects of the invention; FIG. 4 is a diagram of fatigue test conditions; FIG. 5 is a diagram for explaining half peak width; FIG. 6 is a diagram showing measured data in X-ray diffraction analysis of comparative example 1; FIG. 7 is a diagram showing measured data in X-ray diffraction analysis of example 2; FIG. 8 is a diagram showing overlay compositions used in experiments and experimental results showing the effects of the invention according to another embodiment; FIG. 9 is a diagram of seizure test conditions; FIG. 10 is a schematic view of structure observation with a scanning electron microscope of example 12; and FIG. 11 is a schematic view of structure observation with a scanning electron microscope of comparative example 3.

Best Mode for Carrying Out the Invention

The invention is described in more detail with reference to the accompanying drawings.

FIG. l through FIG. 7 show an embodiment of the invention.

In FIG. 1, a section of a slide bearing as a sliding member is schematically shown. Thls slide bearing 1 has a three-layer structure including a back metal 2 made of steel, a bearing alloy layer 3 provided on the upper surface in the drawing of this back metal 2, and an overlays as a sliding layer provided on the upper surface in the drawing of this bearing alloy layer 3. In this cease, the back metal 2 and the bearing alloy layer 3 form a substrate 5, and the overlay 4 is provided on the substrate 5.

As the bearing alloy layer 3, generally, an aluminum-based alloy or a copper-based alloy IS used. The overlay 4 is coated to a thickness of 30 micrometers or less.

FIG. 3 shows compositions of overlays 4 according to Examples 1 through 10 of the invention and a comparative example 1. In this FIG. 3, in Examples 1 through 3 and 7, Sn among Sn, Pb, Bi, In, and Al is used as the base material of the overlay 4, and amorphous carbon (C) is added to the base material. In Examples 4 and 8, an Sn-based Sn-Cu alloy is used as the base material, end amorphous carbon (C) is added "hereto. In Examples and 9, a Pb-based Pb- Sn-Cu alloy and a Pb-Sn-In alloy are used, respectively, and amorphous carbon (C) is added to these. In Examples 6 and 10, Bi and Al are used as the base materials, respectively, and amorphous carbon (C) is added to these.

In Comparative example 1, pure Sn is simply used, and amorphous carbon (C) is not added.

Hereln, Examples 1 through 10 of this invention and omparative example 1 are formed by using a magnetron sputtering apparatus.

Next, a method for coating an overlay 4 of Example 2 among Examples l through 10 is described in detail. The coating methods of Examples l and 3 through 10 and Comparative example L are the same as the coating method of this Example 2. First, a substrate 5 is set at the substrate attaching part of the apparatus, and the targets including Sn to become a raw material of the base material of the overlay and graphite (Gr) to become a raw material of amorphous carbon are attached to a target attaching portion of the apparatus in a predetermined ratio.

Then, the inside of the chamber of the apparatus is vacuumed to l.OxlO-6 tore, and then Ar gas is supplied to the inside of the chamber, and the pressure inside the chamber is adjusted to 2.0x10-3 torn Then, for Ar cleaning of the surface of the substrate 5, a bias voltage of 1000V is applied and Ar plasma is generated between the substrate 5 and the targets, and Ar etching is performed for 15 minutes.

Next, voltages are applied so that a current of 2A through 5A IS supplied to the Sn target and a current of 4A through 7A is supplied to the Gr target.

Then, from the Sn target, Sn atoms are sputtered due to collision of Ar ions and coated on the surface of the substrate 5. In addition, carbon atoms are sputtered from the Gr target due to collision of Ar ions, and are added as amorphous carbon to the overlay. Thereby, an overlay 4 formed by evenly dispersing amorphous carbon ln the base material of Sn is obtained.

En the above-mentioned production method, by supplying methane (CH4) gas to the inside of the chamber without using the Grtarget, DLC that is amorphous carbon containing hydrogen atoms can be added to the base material of Sn. In this case, after Ar etching is performed, the gas to be flown into the apparatus is set to Ar gas and methane gas, and the flow percentage of methane gas in the flow volume of all gases is set to 20 through 50% Then, from the Sn target, Sn atoms are sputtered due to Ar ions and coated on the surface of the substrate 5. The methane gas is decomposed in plasmas, and added as DLC made of C atoms and H atoms to the base material of Sn.

FIG. 2 schematically shows an section of an overlay according to Example 2 coated as described above. In FIG. 2, the reference numeral 6 denotes an Sn crystallite, and 8 denotes the DLC. In this FIG. 2, the crystallite diameter of the base material of Sn is 100 nanometers or less.

Next, a method for measuring the crystallite size (crystallite diameter) of the overlay is described. Herein, an X-ray diffraction analyzer is used to perform X-ray diffraction analysis, and a half peak width of a peak corresponding to a certain crystal phase is determined and substituted for Scherrer's formula (formula (1)) shown below, whereby calculating the crystallite size. The half peak value means, when the peak maximum strength is defined as 1p, a range of 20 to which the strength becomes higher than 1p/2.

B = K\/tcosO (1) Herein, B: expansion of diffraction lines caused by the crystalline size K: form factor I: wavelength of the X-ray used for measurement t: crystallite size O: Bragg angle of diffraction lines When determining the half peak width, the obtained peak is separated into Kal peak and Ka2 peak.

FIG. 6 corresponds to Comparative example 1, and is an example ofJetermining the crystallite size by calculating a half peak width from the peak of, for example, the surface (312) of the overlay made of pure Sn. The half peak width measured and calculated from K1 peak determined from the peak of the surface (312) was 0.070 . As a result, the crystallite size was 150 nanometers.

On the other hand, FIG. 7 corresponds to Example 2 (example of adding 2 percent by mass of amorphous carbon to the Sn base material), and a half peak width is calculated from the peak of the surface (312) of the overlay, and the crystallite size is determined. The half peak width measured and calculated from the Kal peak determined from the peak of the surface (312) was 0.307 . As a result, the crystallite size was 34mm.

The same measurement was made for Examples 1 and 3 through as well as Example 2, the crystallite diameters of the base materials were all 100 nanometers or less, and in particular, the crystallite diameter of Al as the base material of Example was 30 nanometers or less.

To confirm the effects of the invention, a fatigue test was conducted for the Examples 1 through 10 and Comparative example 1. 'l'he test conditions are shown LO EIG. 4. In this case, in the fatigue test, a maximum pressure that does not cause fatigue of the overlay was found byincreasing the pressure in increments ot5MPa. The test results are shown in EIG. 3. FIG. 3 also shows the measuring results of Vickers hardnesses of the overlays (sliding layers).

In FIG. 3, the test results are examined. First, the Comparative example 1 is in the case where the overlay is made of pure Sn, and in this case, the Vickers hardness is low and fatigue resistance is poor. On the other hand, the Vickers hardness becomes higher at20 or more in all cases of the Examples 1 through 10, and fatigue resistance also becomes more excellent than in the Comparative example 1.

Next, Examples 1 through 10 are examined in more detail.

Examples 1 through 3 and 7 are excellent in fatigue resistance, and in addition, Example 1 is comparatively low in hardness and particularly excellent in embeddability, and Examples 2 and 3 are particularly excellent in fatigue resistance since their maximum pressures that the overlays are not fatigued with are 120MPa or more. From these results, the content of amorphous carbon (C) IS preferably 0.1 through 8.0 percent by mass, and more preferably 0.5 through 6 percent by mass.

Example 2 and Example 4 are compared with each other.

Although the contents of amorphous carbon (C) are the same, however, in Example 4, Cu is added and fatigue resistance becomes higher than in Example 2 with no addition of Cu. The reason for this is presumed that the Cu addition increases the mechanical strength and hardness of the sliding layer and increases fatigue resistance.

Example 4 and Example 8 are compared with each other. The consents of amorphous carbon (C)arethesame, however, in Example 4, the content of Cu is 2 percent by mass and fatigue resistance is improved more than in Example 8 with a Cu content more than percent by mass.

In Example 9, Pb is used as a base material and is added with amorphous carbon, Sn, and In. In Example 10, Al is used as a base material and is added with amorphous carbon. In this case, fatigue resistance is also excellent as in the case of other

examples.

From the above-described results, it is proved that Examples 1 through lO of the invention provide sliding members that are particularly excellent in fatigue resistance in their base materials of overlays made of any metals of Sn, Pb, Bi, In, and Al or alloys based on these metals.

FIGS.8throughll show another embodiment oftheinvention.

This embodiment uses an Al-Sn alloy as the base material of the overlay 4 of FIG. 1. In FIG. 8, compositions of Examples 11 through 22 of the invention and Comparatlve examples 2 and 3 are shown. In this FIG. 8, In Examples 11 through 16, an Al-Sn alloy based on Al is added with amorphous carbon, and in Examples 17 through 20, an Al-Sn alloy based on Sn is added with amorphous carbon. In Example 21, an Al-Sn alloy based on Al IS added with Sl and amorphous carbon, and in Example 22, an Al-Sn alloy based on Al IS added with Cu and amorphous carbon.

In comparative examples 2 and 3, an Al-Sn alloy based on Alas used as the base material end amorphous carbon IS not added.

Coating of the overlay 4 in Examples 11 through 22 and Comparative examples 2 and 3 is performed in the same manner as 1n Example 2 described above. In this case, when sputtering, as a target, each pure metal ofSn and A1 or an Al-Sn alloy alloyed in advance by means of casting can be used.

After coating, structural observation of sections of the overlays of Example 12 and Comparative example 3 was performed with a scanning electron microscope. The used scanning electron microscope had 3000 magnifications.

FIG. 10 is a schematic view in structural observation of the section of the overlay of Example 12 with the scanning electron microscope, and FIG. llisaschematlcviewinstructural observation of the section of the overlay of Comparative example 3 with the scanning electron microscope.

As seen in FIG. 11, in the Comparative example 3 In which amorphous carbon is not added, particles of Sn can be observed in A1 with the scanning electron microscope, and the particle diameter of Sn is generally 1 micrometer or more although small particles also exist.

On the other hand, inExample12 added with amorphous carbon, A1 and Sn particles are not observed as shown in FIG. 10. The reason for this IS that A1 and Sn particles were too small to be observed with the scanning electron microscope, and the same observation results as in the case where no particles exist in the overlay were obtained. Incidentally, when the crystallite diameters of the overlay ofthesampleof example 12 were measured by means of X-ray diffraction analysis, the A1 crystallite cryometer was 18 nanometers, and the Sn crystallite diameter was Manometers.

A fatigue test and a seizure test were conducted for the Examples ll through 22 and Comparative examples 2 and 3 and the results of these are shown ln FIG.8. The fatigue test conditions are the same as in FIG. 4. The seizure test condltlons are shown in FIG. 9. In this case, in the seizure test, after running-in, the pressure was increased in increments of Spa, and the maximum pressure that does not cause seizure was found. In FIG. 8, the measuring results of Vickers hardnesses of the overlays are also shown.

In FIG. 3, examining the test results, in comparison with the Comparative examples 2 and 3 in which amorphous carbon is not added, the Examples 11 through 22 in which amorphous carbon was added show higher hardness and improved fatigue resistance due to fineness of crystallites of the metals forming the overlays.

When amorphous carbon is DLC, DLC has a low friction coefficient, so that anti-seizure property Is improved by containing DLC as understood from the comparison between the Example 11 and Comparative example 2 that have the same Sn content.

On the other hand, as understood from Comparative examples 2 and 3, the Sn content is increased lo the Al-Sn alloy, the hardness of the overlay lowers and fatigue resistance lowers.

However, as understood from comparison between the Example 12 and Comparatlve example 3, when amorphous carbon IS added, due to fineness of crystallites, the hardness of the overlay becomes high, so that high fatigue resistance is maintained even when the Sn content is increased.

As understood from Examples12, 14, and 16, the anti-seizure property is improved in proportion to an increase inSn addition.

The following two reasons for improvement in anti-seizure property according to an increase in Sn content are considered.

For sliding, a lubricant assumes a very important role.

When the lubricant exists between two members that slide and form an of] film, no seizure occurs. Therefore, the overlay of the slide bearing IS preferably made of a material that easily forms an oil film. Wettability with the lubricant as a parameter indicating the forming easiness of the oil film is higher in Sn than lo Al. Therefore, the more Sn contained ln the overlay, the higher the antl-seizure property. This is the first reason.

The second reason 1S as follows. When the lubricant runs out between two members to slide, frictional heat is generated.

When the oil film starts partially running out, the frictional heat is only locally generated, however, when the running out area of the oil film increases, the frictional heat increases and adhesion occurs between the two members and causes seizure.

However, in the case where Sn as a low-melting point metal exists in the overlay, when the oil film starts partially running out, Sn locally melts. Latent heat in this case absorbs the frictional heat, so that the frictional heat 1S not accumulated, and as a result, seizure is prevented.

By thus increasing the Sn content, anti-seizure property is improved. in addition, by adding amorphous carbon, fatigue resistance is improved due to fineness of crystallltes, so that the anti-seizure property can beimproved while improving the tatque resistance.

This improvement in fatlque resistance and anti-seizure property due to an increase in Sn content when amorphous carbon is added is obtained not limitedly in the Al-Sn alloy based on Al, and as shown in Examples 17 through 20, anti-seizure property can also be improved while ma1ntaininq excellent fatigue resistance in an Al-Sn alloy based on Sn by increasing the Sn content ln the same manner.

10Furthermore, as understood from comparison between the Examples21and22 andExamplel4, by containing SiandCu, fatigue resistance can be improved, and lo particular, when Si is contained, anti-seizure property is also simultaneously improved.

15The inventionis not 1lmltedLotheexamples described above, and is alterable, for example, as follows.

In the slide bearing 1, although the overlay 4 IS directly provided on the upper surface of the bearing alloy layer 3, it is also possible that an intermediate layer of Ni-Cr or Ti, etc., is provided on the upper surface of the bearing alloy layer 3 and the overlay 4 is provided on the upper surface of this intermediate layer. It is also possible that the overlay 4 is directly provided on the upper surface of the back metal 2.

Furthermore, a conforming layer made of a soft metal such as pure Sn or a resin such as PAI can be provided on the upper surface of the overlay 4.

In can be used as the base material of the overlay 4. The metal to be added for increasing the mechanical strenqth and hardness of the overlay 4 IS not limited to Cu. and any of Sb, Ag, and Cd can be used or two or more kinds of these can be used.

Industrial Applicabllity As described above, the sliding member of the invention is useful as a slide bearing having a sliding layer with a thickness of 30 micrometers or less called overlay on the bearing alloy.

Claims

l.Aslidingmembercomprisingaslidinglayeron a substrate, wherein the sliding layer contains any metal of Sn, Pb, Bi, In, and A1 or an alloy based on the metal as a base material, and amorphous carbon is added to this base material.
2. The sliding member according to claim 1, wherein the crystallite diameter of the base material is 100 nanometers or less.
3. The sliding member according to claim 1, wherein any one or more metals of Sn, Pb, Bi, In, A1, Cu. Sb, Ag, and Cd are added to the base material.
4. The sliding member according to claim 2, wherein any one or more metals of Sn, Pb, Bi, In, A1, Cu. Sb, Ag, and Cd are added to the base material.
5. The sliding member according to claim 3, wherein when the added metal is any one or more metals of Sn, Pb, Bi, In, and A1, the contents of the added metals are 20 percent by mass or less, and the total content of these added metals is 30 percent by mass or less.
6. The sliding member according to claim 4, wherein when the added metal 1s any one or more metals of Sn, Pb, Bi, In, and A1, the content of each added metal is 20 percent by mass or less, and the total content of these added metals IS 30 percent by mass or less.
7. The sliding member according to any one of claims 3 through 6, wherein when the added metal is any one or more metals of Cu. Sb, Ag, and Cd, the contents of the added metals are 5 percent by mass or less, and the total content of these added metals is 10 percent by mass or less.
8. The sliding member according to claim 1, wherein the base material of the sliding member is made of an alloy of A1 and Sn containing 20 through 80 percent by mass of A1 and 20 through percent by mass of Sn, and amorphous carbon is added to the base material of this Al-Sn alloy.
9. The sliding member according to claim 8, wherein any one or more metals of Si, Cu. Sb, In, and Ag are added to the Al-Sn alloy forming the base material.
10. The sliding member according to claim 9, wherein the content of each of Si, Cu. Sb, In, and Ag IS 5 percent by mass or less as a simple substance, and the total content of these is 10 percent by mass or less.
11. The sliding member according to any one of claims 8 through 10, wherein the particle diameter of A1 or Sn in the base material is 1 micrometer or less.
12. The sliding member according to any one of claims 8 through 10, wherein the particle diameter of Al or Sn in the base material is 0.05 micrometers or less.
13. The sliding member according to claims 8 through 10, wherein the crystallite diameter of the base material is 30 nanometers or less.
14. The sliding member according to claim 11, wherein the crystallite diameter of the base material is 30 nanometers of less.
15. The sliding member according to claim 12, wherein the crystallite diameter of the base material is 30 nanometers or less.
16. The sliding member according to any one of claims 1 through 6 and 8 through 10, wherein the content of amorphous carbon is 0.1 through 8 percent by mass.
17. The sliding member according to claim 7, wherein the content of amorphous carbon is 0.1 through 8 percent by mass.
18. The sliding member according to claim 11, wherein the content of amorphous carbon is 0.1 through 8 percent by mass.
19. The sliding member according to claim 12, wherein the content of amorphous carbon is 0.1 through 8 percent by mass.
20. The sliding member according to claim 13, wherein the content of amorphous carbon is 0.1 through 8 percent by mass.
21. The sliding member according to claim 14, wherein the content of amorphous carbon is 0.1 through 8 percent by mass.
22. The sliding member according to claim 15, wherein the content of amorphous carbon is 0.1 through 8 percent by mass.
23. The sliding member according to any one of claims 1 through 6 and 8 through 10, wherein the thickness of the sliding layer is 30 micrometers or less.
24. The sliding member according to claim 7, wherein the thickness of the sliding layer is 30 micrometers or less.
25. The sliding member according to claim 11, wherein the thickness of the sliding layer is 30 micrometers or less.
26. The sliding member according to claim 12, wherein the thickness of the sliding layer is 30 micrometers or less.
27. The slldlng member according to claim 13, wherein the thickness of the sliding layer is 30 micrometers or less.
28. The sliding member according to claim 14, wherein the thickness of the sliding layer is 30 micrometers or less.
29. The sliding member according to claim 15, wherein the thickness of the sliding layer is 30 micrometers or less.
30. The sliding member according to claim 16, wherein the thickness of the sliding layer is 30 micrometers or less.
31. The sliding member according to claim 17, wherein the thickness of the sliding layer is 30 micrometers or less.
32. The sliding member according to claim 18, wherein the thickness of the sliding layer is 30 micrometers or less.
33. The sliding member according to claim 19, wherein the thickness of the sliding layer is 30 micrometers or less.
34. The sliding member according to claim 20, wherein the thickness of the sliding layer is 30 micrometers or less.
35. The sliding member according to claim 21, wherein the thickness of the sliding layer is 30 micrometers or less.
36. The sliding member according to claim 22, wherein the thickness of the sliding layer is 30 micrometers or less.