JPH10330871A - Sliding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member free from Pb at least in the sliding surface and capable of showing sliding characteristic equal to that of a sliding member containing Pb in the sliding surface. SOLUTION: A coating layer 3, having a composition consisting of at least Sn between Sn and In and the balance essentially Zn with inevitable impurities, is formed on the sliding surface to a mating material, at the surface of a base material. This coating layer further contains at least one element selected from the group consisting of Sb, Cu, Ag, and Au. Although this sliding member is free from Pb in the sliding surface, it shows sliding characteristic equal to that of a sliding material containing Pb in the sliding surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sliding member, and more particularly to a sliding member containing no Pb (lead). INDUSTRIAL APPLICABILITY The sliding member of the present invention can be suitably used, for example, for a slide bearing or a bush for an internal combustion engine.

[0002]

2. Description of the Related Art Plain bearings applied to crankshafts, connecting rods and the like for automobile engines include:
With the increase in engine output, kelmet bearings having both initial conformability and strength (compression strength, fatigue strength) have been widely used in recent years. In this kelmet bearing, kelmet (an alloy containing Cu and Pb as a main component) is lined on a back metal made of low carbon steel, and a thin overlay layer (Pb and Sn is mainly formed on a sliding surface with a mating material on the kelmet surface). An alloy layer as a component) is formed by electroplating or the like. In addition, from the viewpoint of improving the corrosion resistance of kelmet, a surface of the kelmet is subjected to Ni plating to a thickness of about several μm, and an overlay layer is formed on the Ni plated layer.

[0003] In the above-mentioned plain bearing, Sn is added to the Al base.
And an aluminum alloy bearing obtained by alloying Pb or the like (see Japanese Patent Application Laid-Open No. 4-219523) is also widely used.

[0004]

Incidentally, as a trend of material development in recent years, the direction of Pb-free is progressing. This development trend is no exception for sliding members such as the above-mentioned plain bearings. However, in sliding members such as sliding bearings,
Pb is important for satisfying the sliding characteristics. Therefore, it has been extremely difficult to provide a sliding member having sufficient sliding characteristics without containing Pb in the sliding surface.

The present invention has been made in view of the above circumstances, and at least does not contain Pb on the sliding surface.
It is a technical problem to be solved to provide a sliding member capable of exhibiting the same sliding characteristics as those having a sliding surface.

[0006]

[Means for Solving the Problems]

(1) The sliding member according to claim 1, which solves the above problem,
In a sliding member comprising a base material and a coating layer formed on a sliding surface of the base material on a sliding surface with a mating material, the coating layer is formed of S
It contains at least Sn of n and In, and the balance substantially consists of Zn and unavoidable impurities.

(2) The sliding member according to the second aspect is the sliding member according to the first aspect, wherein S is contained in the coating layer.
The total amount of n and In is 40 to 70% by weight. The total amount of Sn and In contained in the coating layer refers to the Sn content when only Sn is included in the coating layer, and both Sn and In are included in the coating layer. In this case, it refers to the total content of Sn and In.

(3) The sliding member according to the third aspect is the sliding member according to the second aspect, wherein the coating layer is formed of Sn and In.
And the amount of Sn contained in the coating layer is 20
To 60% by weight, and the amount of In contained in the coating layer is 2 to 20% by weight. (4) The sliding member according to the fourth aspect is the sliding member according to the first aspect, wherein the coating layer is made of Sb, Cu, Ag, and A.
It is characterized by further containing at least one selected from the group consisting of u.

(5) The sliding member according to the fifth aspect is the sliding member according to the fourth aspect, wherein S is contained in the coating layer.
The total amount of at least one selected from the group consisting of b, Cu, Ag and Au is 0.05 to 5.0% by weight. (6) The sliding member according to claim 6 is the sliding member according to claim 1, wherein the coating layer is a plating film formed by plating a surface of the base material. I do.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The sliding member of the present invention comprises a base material and a coating layer formed on the surface of the base material on the sliding surface with the mating material. The type of the base material is not particularly limited, and can be appropriately selected from steel, cast iron, an iron-based sintered alloy, an aluminum alloy, a copper alloy, and the like, depending on the member to which the sliding member of the present invention is applied. And a composite material of these materials. However, it is preferable that this substrate also does not contain Pb. For example, when the sliding member of the present invention is applied to a slide bearing for an internal combustion engine, the steel back metal is made of Cu-Sn.
Base material obtained by lining a base alloy layer, Al-Sn-S
A substrate made of an i-based alloy layer or the like can be used.

The coating layer is preferably a plating film formed by plating the surface of a substrate. This is because if the coating layer is a plating film, it is advantageous in terms of adhesion and film strength. As this plating process,
In addition to wet plating such as electroplating and chemical plating, dry plating by a PVD method such as ion plating and sputtering can be employed. In addition, as a method of forming a coating layer on a base material, thermal spraying or the like can be adopted in addition to plating.

Although a coating layer may be formed directly on the surface of the substrate, an intermediate layer is formed on the surface of the substrate from the viewpoint of improving the bonding property between the substrate and the coating layer and the corrosion resistance of the substrate. Is preferred. As the intermediate layer, a Ni plating layer, Co
A plating layer, a Zn plating layer, or the like can be employed. The thickness of the coating layer is preferably 1.0 to 30 μm. If the thickness of the coating layer is less than 1.0 μm, it becomes difficult to exhibit sufficient sliding characteristics, while 30 μm
If the thickness is larger than the above, the adhesiveness is reduced and the coating layer is easily peeled off from the substrate surface. More preferably, the thickness of the coating layer is 10 to 30.
μm. When the thickness of the coating layer is 10 μm or more, it is advantageous in terms of securing necessary conformability and abrasion life.

The above-mentioned coating layer contains at least Sn of Sn (tin) and In (indium), and the balance substantially consists of Zn (zinc) and unavoidable impurities. Is not contained. A coating layer containing only Sn of Sn and In and the balance substantially consisting of Zn and unavoidable impurities (hereinafter, referred to as a coating layer made of a Zn—Sn alloy) does not have excessively high hardness and conformability. And abrasion resistance, especially at high temperatures.

Therefore, the sliding member according to the present invention in which the coating layer made of the Zn—Sn alloy is formed on the sliding surface with the mating material on the surface of the base material, does not contain Pb at least on the sliding surface. Nevertheless, the sliding properties of conformability and wear resistance are improved. Here, if the content of Sn in the coating layer made of the Zn—Sn alloy is less than 40% by weight, the hardness becomes too high and the conformability becomes insufficient. On the other hand, when the Sn content exceeds 70% by weight, the melting point of the alloy is lowered, and the wear resistance at high temperatures becomes insufficient. Therefore, the content of Sn in the Zn—Sn alloy is 40%.
It is preferable to set it to 70% by weight.

A coating layer containing both Sn and In and the balance substantially consisting of Zn and unavoidable impurities (hereinafter referred to as Zn-
It is called a coating layer made of a Sn—In alloy. ) Is the above Zn
As in the case of the coating layer made of the -Sn alloy, the hardness is not too high, the conformability is good, and the wear resistance, particularly the wear resistance at high temperatures, is good. In addition, due to the function of In, lubrication is good and seizure resistance is good.

Therefore, the sliding member according to the present invention in which the coating layer made of the Zn—Sn—In alloy is formed on the sliding surface with the mating material on the surface of the substrate, at least the Pb is formed on the sliding surface.
, The sliding properties of conformability, wear resistance and seizure resistance are improved. Here, the Zn
In the coating layer made of a Sn—In alloy, Sn and I
When the total amount of n is less than 40% by weight, lubricity is deteriorated and seizure resistance becomes insufficient. On the other hand, Sn and I
If the total amount of n exceeds 70% by weight, the melting point of the alloy decreases, and the wear resistance at high temperatures becomes insufficient. Therefore, Sn and In in the Zn—Sn—In alloy are used.
Is preferably 40 to 70% by weight.

Further, in the coating layer made of the Zn—Sn—In alloy, if the In content is less than 2% by weight, there is no effect on the improvement of lubricity. And the wear resistance becomes insufficient.
Therefore, the content of In in the Zn-Sn-In alloy is preferably set to 2 to 20% by weight. And
In the coating layer made of the Zn—Sn—In alloy,
Since the total content of n and In is preferably 40 to 70% by weight, and the content of In is preferably 2 to 20% by weight, the Sn content is 20 to 6%.
It is preferably 0% by weight.

Further, the coating layer made of the Zn—Sn alloy or the coating layer made of the Zn—Sn—In alloy is
b (antimony), Cu (copper), Ag (silver) and Au
It is preferable to further contain at least one selected from the group consisting of (gold). The Sb forms a compound in coexistence with Sn, and the Zn—Sn alloy and the Zn
-It contributes to the improvement of the wear resistance of the Sn-In alloy. When the content of Sb is less than 1.0% by weight, there is almost no effect of improving the wear resistance. Therefore, the content of Sb is 1.0 to 5.0% by weight.
It is preferable that

The Cu contributes to the improvement of the wear resistance of the Zn—Sn alloy and the Zn—Sn—In alloy. C
If the content of u is less than 0.05% by weight, there is almost no effect of improving the wear resistance, while if it exceeds 0.5% by weight, the corrosion resistance is reduced. For this reason, the content of Cu is 0.05 to 0.1.
Preferably it is 5% by weight. The Ag is the Zn
-It contributes to the improvement of wear resistance and corrosion resistance of the Sn alloy and the Zn-Sn-In alloy. Ag content is 0.1% by weight
If the amount is less than the above, there is almost no effect of improving the wear resistance and the corrosion resistance. Therefore, the content of Ag is preferably set to 0.1 to 2.0% by weight.

The Au is, like the Ag, the Zn-
It contributes to the improvement of the wear resistance and corrosion resistance of the Sn alloy and the Zn-Sn-In alloy. When the content of Au is less than 0.1% by weight, there is almost no effect of improving wear resistance and corrosion resistance.
On the other hand, if the content exceeds 2.0% by weight, the hardness of the alloy increases and the material cost increases. Therefore, the content of Au is preferably set to 0.1 to 2.0% by weight.

It is preferable that the total content of at least one content selected from the group consisting of Sb, Cu, Ag and Au is 0.05 to 5.0% by weight. Therefore, the sliding member of the present invention can be suitably used for a slide bearing or a bush for an internal combustion engine.

[0022]

The present invention will be described below in detail with reference to examples. [First Embodiment] A Cu-Sn alloy (Cu:
94.5% by weight, Sn: 5% by weight) A test piece was prepared, and on the surface of the Cu-Sn alloy of the test piece,
A coating layer having a chemical composition shown in Table 1 and having a thickness of 10 to 30 μm was formed by electroplating.

[0023]

[Table 1]

(Examples 2, 7, 8, 13, 15) Electroplating was performed using a stannate-cyanide bath of a Zn-Sn plating solution having the composition shown in Table 2 under the plating conditions shown in Table 3. Thus, a coating layer made of a Zn—Sn alloy was formed.

[0025]

[Table 2]

[0026]

[Table 3] (Examples 1, 3, 5, 6, and 11) Using a stannate-cyanide bath of a Zn—Sn plating solution having the composition shown in Table 2,
By performing electroplating under the plating conditions shown in Table 3, a plating film made of a Zn-Sn alloy was formed. Then, after further In plating is performed on the plating film, In is diffused into the plating film by a heat treatment (150 to 170 ° C., 30 to 60 minutes) to be treated so as to have a composition shown in Table 1. Thus, a coating layer made of a Zn—Sn—In alloy was formed.

The In plating uses a sulfamic acid bath, a plating solution temperature: 20 to 30 ° C., and a current density: 1 to 5
The test was performed under the condition of A / dm ² . (Example 4) In a Zn-Sn plating solution having a composition shown in Table 2, deciano-gold (monovalent)-is used so that Au becomes an ion.
Using a stannate-cyanide bath to which potassium acid was added so as to have the composition shown in Table 1, electroplating was performed under the plating conditions shown in Table 3, whereby Zn containing a trace amount of Au was
A plating film made of a Sn alloy was formed. Then, after further performing In plating on the plating film, In is diffused into the plating film by a heat treatment and treated so as to have a composition shown in Table 1, whereby Zn-Sn containing a trace amount of Au is obtained. A coating layer made of a -In alloy was formed.

Example 9 Zn having the composition shown in Table 2
Using a stannate-cyanide bath in which antimony chloride is added to the Sn plating solution so that Sb becomes an ion so as to have the composition shown in Table 1, electroplating is performed under the plating conditions shown in Table 3 to obtain Sb. Zn-Sn containing a trace amount of
A plating film made of an alloy was formed. Then, after In plating is further performed on the plating film, In is diffused into the plating film by a heat treatment to be treated to have a composition shown in Table 1, whereby Z containing a trace amount of Sb is contained.
A coating layer made of an n-Sn-In alloy was formed.

(Examples 10 and 12) Copper sulfide EDTA (ethylenediaminetetraacetic acid) was added to a Zn-Sn plating solution having a composition shown in Table 2 so that Cu became an ion so as to have a composition shown in Table 1. Using a stannate-cyanide bath, electroplating was performed under the plating conditions shown in Table 3 to form a plating film made of a Zn-Sn alloy containing a trace amount of Cu. Then, after In plating is further performed on the plating film, In is diffused into the plating film by a heat treatment to be treated to have a composition shown in Table 1, whereby Zn-Sn containing a trace amount of Cu is obtained. -In
A coating layer made of an alloy was formed.

Example 14 Z having the composition shown in Table 2
AgCN is added to the n-Sn plating solution so that Ag becomes ions.
Is electroplated under the plating conditions shown in Table 3 using a stannate-cyanide bath added so as to have a composition shown in Table 1 to obtain a plating film made of a Zn-Sn alloy containing a trace amount of Ag. Formed. Then, after In plating is further performed on this plating film, I
By diffusing n into the plating film and treating it to have the composition shown in Table 1, Zn-
A coating layer made of a Sn-In alloy was formed.

(Comparative Example 1) Using a plating solution comprising a fluorinated bath, a plating solution temperature of 20 to 30 ° C. and a current density of 2 to 5
By plating under the condition of A / dm ² , Pb-
A coating layer made of a Sn alloy was formed. (Comparative Example 2) A plating film composed of a Pb-Sn alloy was formed by plating using a plating solution composed of a borofluoride bath at a plating solution temperature of 20 to 30 ° C and a current density of ^{2 to} 5 A / dm ^2. did. Then, after In plating was further performed on the plating film, In was diffused into the plating film by heat treatment to form a coating layer made of a Pb-Sn-In alloy.

(Comparative Example 3) Using a plating solution composed of a fluorinated bath, a plating solution temperature of 20 to 30 ° C and a current density of 2 to 5
By performing plating treatment under the condition of A / dm ^2, a coating layer made of Pb—Sn containing a trace amount of Cu was formed. (Comparative Example 4) A coating layer made of Sn was formed by plating using a plating solution consisting of a borofluoride bath under the conditions of a plating solution temperature of 20 to 30 ° C and a current density of ^{2 to} 5 A / dm ² .

(Evaluation of Hardness) The hardness of the coating layers of Examples 1 to 15 and Comparative Examples 1 to 4 was measured with a micro-Vickers hardness tester. The results are shown in Table 4 and FIG. (Evaluation of friction and wear test) φ7 mm × L12 m in which the coating layers of Examples 1 to 15 and Comparative Examples 1 to 4 were formed on the sliding surface.
A friction and wear test was performed on a test piece consisting of m pins. The results are shown in Table 4 and FIGS. The test conditions are as follows.

Test apparatus: Pin-on-disk test machine Sliding speed: 0.5 m / s Load: 9 N Lubrication: No lubrication (in a vacuum of 5 × 10 ⁻² Torr) Temperature: Room temperature Test time: 30 minutes (however, abrasion loss) In the case of a steel sheet having a long time of less than 30 minutes, it was converted as having undergone abrasion for 30 minutes.) Opponent material: disk test piece, steel (HV400) (evaluation of seizure resistance) Example 1
30 mm x 30 mm formed with a coating layer of ~ 4 on the sliding surface,
A seizure test was performed on a test piece composed of a plate having a thickness of 2 mm (sliding surface 30 mm × 30 mm). The results are shown in Table 4 and FIG. The test conditions are as follows.

Test apparatus: Cylindrical × plate test piece thrust tester Sliding speed: 2.0 m / s Load: Step-up asymptotic method (5 kgf / step) Lubrication: 5W-30 base oil (oil bath) Temperature: Room temperature to room temperature Test time: Step up / every 5 minutes Mate material: Cylindrical test piece, steel (HV600)

[0036]

[Table 4]

As is clear from Table 4 and FIGS.
In Examples 1 to 15, the hardness was higher than in Comparative Examples 1 to 4, and the abrasion resistance was all significantly excellent. Example 1
Nos. To 15 have slightly higher friction coefficients than Comparative Examples 1 to 4. Further, in Comparative Examples 1 to 4, the coating layer was worn out during the seizure test, resulting in seizure with a low load, whereas Examples 1 to 15 were compared with Comparative Example 1 in which the coating layer was made of a Pb-Sn alloy. And exhibited seizure resistance superior to or equal to the above.

In Examples 3 to 6, 9 to 12, and 14, the seizure resistance was particularly improved because the coating layer was made of a Zn-Sn-In alloy containing In which contributes to improvement in lubricity. Above all, Examples 4, 9, 10, 12, and 14 further include a trace element contributing to the improvement of the wear resistance, so that the wear resistance was particularly improved. In particular, Example 6 shows excellent sliding properties due to the balance of the amounts of Sn and In, and Examples 10 and 14 show the excellent sliding characteristics due to the balance of the amounts of Sn and In and the balance of trace elements that contribute to wear resistance. Was.

In Examples 1, 2, and 5, the hardness of the coating layer was high and the lubricating properties were slightly inferior to those of the other examples, so that the seizure resistance was low. [Second Embodiment] In this embodiment, the sliding member of the present invention is applied to a slide bearing for an internal combustion engine. As shown in FIG. 5, a steel backing metal 1 has a C
A base material was prepared by lining a u-Sn alloy layer (Cu: 94.5 wt%, Sn: 5 wt%) 2. A 1.5 μm thick Ni plating layer 2 ′ was formed on the surface of the Cu—Sn alloy layer 2 of the substrate, that is, on the sliding surface with the counterpart material.
The plating conditions at this time were plating solution: watt bath,
Plating solution temperature: 50 ° C., current density: 6 A / dm ² .

Then, on the surface of the Ni plating layer 2 ′,
The coating layer 3 was formed in the same manner as in the first embodiment to produce a plain bearing. A bearing alone test was performed on the case where the coating layers of Examples 1 to 15 and Comparative Examples 1 to 4 shown in the first example were applied to the coating layer 3 of the above-mentioned plain bearing. FIG. 6 shows the result. The test conditions are as follows.

Test device: Static load bearing tester Revolution: 5000 rpm (peripheral speed: 12.5 m / s) Lubricating oil: SAE10W-30 Lubricating amount: 0.1 liter / min Lubricating temperature: 100 ° C. Opposite material: cast iron ( (S50C, quenching, surface roughness: 0.8 μm) As is clear from FIG. 6, by forming the coating layer according to the present invention on the sliding surface with the mating material on the surface of the sliding bearing,
Bearing performance equal to or higher than Comparative Examples 1 to 4 could be exhibited.

In the above example, the results in the case where the coating layer was formed by electroplating were shown. However, it was confirmed that the same results were obtained when the coating layer was formed by vapor phase plating such as PVD. did.

[0043]

As described in detail above, the sliding member of the present invention does not contain Pb on the sliding surface, but exhibits the same sliding characteristics as those containing Pb on the sliding surface. Can be.

[Brief description of the drawings]

FIG. 1 is a bar graph showing measurement results of hardness of a coating layer according to a first example.

FIG. 2 is a bar graph showing an evaluation result of a friction coefficient of a coating layer according to the first embodiment.

FIG. 3 is a bar graph showing evaluation results of seizure resistance of a coating layer according to the first example.

FIG. 4 is a bar graph showing evaluation results of abrasion resistance of a coating layer according to the first example.

FIG. 5 is a partial sectional view of a sliding bearing according to a second embodiment.

FIG. 6 is a bar graph showing an evaluation result of seizure resistance of a coating layer according to a second example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steel back metal, 2 ... Cu-Sn alloy layer, 2 '... Ni plating layer, 3 ... Coating layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshio Fuwa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. 1 Toyota Central Research Laboratory Co., Ltd. (72) Inventor Shigeru Hotta 41 Toyota Central Research Laboratory Co., Ltd.

Claims (6)

[Claims] 1. A sliding member comprising a base material and a coating layer formed on a sliding surface of the base material with a mating material, wherein the coating layer has at least Sn of Sn and In. A sliding member comprising, and the balance substantially consisting of Zn and unavoidable impurities. 2. The total amount of Sn and In contained in the coating layer is 40 to 70% by weight.
The sliding member as described in the above. 3. The coating layer contains both Sn and In, and the amount of Sn contained in the coating layer is 20 to 60% by weight.
The sliding member according to claim 2, wherein the amount of In contained in the coating layer is 2 to 20% by weight. 4. The coating layer is made of Sb, Cu, Ag and Au.
The sliding member according to claim 1, further comprising at least one member selected from the group consisting of: 5. Sb, Cu, Ag contained in the coating layer
The sliding member according to claim 4, wherein the total amount of at least one selected from the group consisting of Au and Au is 0.05 to 5.0% by weight. 6. The sliding member according to claim 1, wherein said coating layer is a plating film formed by plating a surface of said base material.