JP2001152210A - Al-Bi based sintered bearing alloy and method for producing the same - Google Patents

Abstract

(57) [Problem] To develop an Al-based bearing alloy having excellent wear resistance replacing conventional Al-Pb alloy and Al-Sn alloy without using Pb whose use is restricted from the viewpoint of environmental problems. I do. [Constitution] Bismuth is 3 to 50% by volume, and the remaining 9
7 to 50% by volume of an alloy composed of Al or bismuth is 3 to 50% by volume, and the remaining 97 to 50% by volume is Al
An Al-Bi based sintered bearing alloy, which is an alloy having a composition of 97% by weight and 3% by weight of Mg. If the total content of copper and graphite is 15% by volume or less, the specific wear amount is further reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a conventional Al-Pb
The present invention relates to an Al-Bi-based sintered bearing alloy having excellent wear resistance replacing a bearing alloy such as an Al-Sn-based alloy.

[0002]

2. Description of the Related Art At present, most commonly used bearing alloys include copper-lead alloy bearings plated with overlay (Kelmet alloy: Cu-Pb-Ni-Sn alloy, Cu-lead alloy).
(Pb-Ag-Sn alloy system, Pb: 23-42 wt%).

[0003] Overlay plated bearings have the drawback of increasing costs due to the increased number of manufacturing steps.
In addition, copper-lead alloy bearings without overlay plating, which are often used for medium loads, have a problem of corrosion due to recent exhaust gas regulations and prolonged oil replacement periods.

Therefore, in recent years, the development of an Al-based bearing alloy having excellent corrosion resistance, load resistance, and conformability has been highlighted as an important issue, and several Al-based bearing alloys have been developed mainly in the United States. Have been. As an Al-based bearing alloy that has been developed, US General Motor
GM developed metal (melted material) and Diacl
Al-Pb alloys such as Evite's Gold Metal (powder rolled material) and Al-Sn developed by Alcoa
System alloy (melted material).

[0005]

A problem in the production of an Al-Pb alloy is that the difference in specific gravity between Al and Pb is so large that Pb is not sufficient for production on the ground (under gravitational environment).
No content was obtained (limit of 12% by weight).
In the case of Sn-based alloys, since Sn has poor surface performance on the shaft, sufficient bearing performance could not be imparted to any of the alloys, such as causing excessive wear.

Recently, the present inventor has developed a manufacturing method capable of easily mixing metals having a large specific gravity difference even in a non-gravity environment, and has developed an Al-P having excellent bearing characteristics.
b-type bearing alloy (SUT metalA and SUT metalB)
(JP-B-62-6625, JP-B-62-29497, JP-B-3-46536, and JP-A-7-300644). However, from the viewpoint of environmental issues, the use of Pb after 2000 is restricted, and the goal is to eliminate the use of Pb except for the purpose of using the battery.

[0007]

Under these circumstances, the present inventor has attempted to develop a new bearing alloy which replaces the conventional Al-Pb alloy or Al-Sn alloy, and has developed various types of Al alloys having excellent bearing performance. As a result of studying alloy bearing alloys and their manufacturing methods, new Pb-free sintered Al-Bi-based bearings that use Pb and are not only Al-bearing alloys but also lead-bronze-based alloys (LBC4) The alloy was successfully developed.

That is, according to the present invention, bismuth is contained in an amount of 3 to 50.
Alloy containing 100% by volume and the remaining 97 to 50% by volume of Al, or an alloy containing 3 to 50% by volume of bismuth and 97 to 50% by volume of the remaining 97% by weight of Al and 3% by weight of Mg. It is an Al-Bi based sintered bearing alloy characterized by the following. In the above composition, bismuth is 10.2 to 78.7% by weight in terms of weight, the balance of aluminum alloy or bismuth is 26.8 to 78.7% by weight, and magnesium is 0.6 to 2.7% by weight. , The remainder being an aluminum alloy. Within this composition range, the Al-Bi sintered bearing alloy of the present invention exhibits the smallest specific wear when bismuth is about 40% by volume.

Further, the present invention provides a sintered alloy in which specific wear is further reduced by adding copper and graphite in addition to the above alloy composition, that is, bismuth is 3 to 50% by volume, and the total amount of copper and graphite is The amount is 15% by volume or less, and the remaining volume% is made of aluminum or bismuth is 3 to 5%.
Al-Bi is 0% by volume, the total amount of copper and graphite is 15% by volume or less, and the remaining volume% is an alloy having a composition of 91% by weight of Al and 3% by weight of Mg.
Series sintered bearing alloy.

Further, the present invention provides a method of mixing raw material powders at a predetermined ratio so as to obtain the above-mentioned respective alloy compositions, and performing compacting.
A method for producing an Al-Bi-based sintered bearing alloy, comprising sintering at 520 to 640 ° C in an inert atmosphere at normal pressure. In order to contain copper and graphite in the above sintered alloy, it is preferable to use copper-plated graphite powder as a raw material.

In Al-Bi-based sintered alloys, Al-Sn-based sintered alloys, and Al-In-based sintered alloys, soft metal bases are finely and uniformly dispersed in Al to obtain an ideal structure as a bearing alloy. be able to. When Bi, Sn, and In are added to Al, conformability appears, and the specific wear amount decreases. Thereby, it turned out that these metal components have the effect of suppressing wear. In particular, the wear resistance of the sintered alloy to which Bi was added was greatly improved. In addition, when the sintered alloy contains 15% by volume or less of copper and graphite in a sintered alloy by a method of mixing graphite powder with copper plating (hereinafter referred to as “plated graphite graphite powder”) in the raw material powder, the wear resistance is further improved. Since the flexural strength decreases as the content of copper and graphite increases, the upper limit of copper and graphite is preferably about 15% by volume.

Al-Bi based sintered alloys, Al-Sn based sintered alloys and Al-In based sintered alloys are practical alloys G
M metal (Al-8wt% Pb) and Goul
dmetal (Al-8.5 wt% Pb-4.0 wt%
Si-1.5 wt% Sn-1.0 wt% Cu). In particular, Al-Bi based sintered alloys
4 types of lead bronze (LBC4) and Al-Pb alloy (SUT m
etalA: Al-44.8 wt% Pb-1.3 wt%
(Mg). The optimum amount of the soft metal added to Al was 40% by volume of Bi, 12% by volume of Sn, and 18% by volume of In. Further, the Al-Bi based sintered alloy to which the plated graphite powder is added is a sintered alloy (SUT metal B: Al-Pb) to which the plated graphite powder is added.
-43.3% Pb-1.2% Mg-6.5% Cu-6.
A specific wear amount equivalent to 5% Gr) was obtained. From these results, it can be said that the Al-Bi-based sintered alloy has performance comparable to that of the Al-Pb-based sintered alloy.

In the sintered alloy of the present invention, Bi is a soft metal component having low toxicity which replaces Pb, Sn, and In of the conventional alloy, and has a smaller specific wear than the bearing alloy using Pb, Sn, and In. It turned out to be obtained. There is a close relationship between the metal structure of the bearing alloy and wear resistance, and materials in which soft metals are finely distributed in a mesh form have good conformability,
The specific wear is also small. Mg forms a compound of Bi and Mg ₃ Bi ₂ or BiMg, which acts to improve sinterability and strength, so that it is desirable to contain the above-mentioned predetermined amount.

The particle size of the Al powder, Mg powder, Bi powder and copper-plated graphite powder as raw materials for producing the sintered bearing alloy of the present invention is 10
A powder having an average particle size of 7.3 μm or less for Al powder, 75 μm or less for Mg powder, 75 μm or less for Bi, and 149 μm or less for plated graphite powder is preferably used. In addition, copper powder and graphite powder can also be used in place of the plated copper graphite powder.

After mixing these raw material powders at a predetermined mixing ratio so that the composition of the sintered body is within the composition range of each alloy of the present invention, dry mixing is performed for about 30 minutes. Next, using zinc stearate or the like as a lubricant, the mixed powder was filled in a mold, and
It is molded at about 400 MPa for about 60 minutes to produce a green compact. Next, the temperature of the green compact is increased at a rate of about 15 ° C./min, and the pressure of
Sinter at 0-640 ° C. The more preferable sintering temperature for dispersing the soft metal finely and uniformly in the form of a mesh is 580 to 580.
600 ° C.

FIG. 1 shows Bi of an Al-Bi sintered bearing alloy in which the bismuth content is in the range of 3 to 50% by volume, and the remaining 97 to 50% by volume is 97% by weight of Al and 3% by weight of Mg. It is a graph which shows the relationship between content and (mm < ³ > / Nmm) about the case where sintering temperature is 580 degreeC, 600 degreeC, 620 degreeC, and 640 degreeC. The abrasion test was performed using an Ogoshi quick abrasion tester, mating material SUJ2 (high carbon chromium bearing steel), final load of 20.6N, sliding speed of 3.55m.
/ S, abrasion distance of 66.6 m to 600 m, in air, without lubrication. FIG. 2 shows Al-40 volume% Bi alloy and Al-40 volume% Bi-15 volume% (Cu-graphite).
4 is a graph showing a relationship between a friction distance of an alloy and a specific wear amount.
The Al-40% by volume Bi-15% by volume (Cu-graphite) alloy shows a smaller specific friction amount than the Al-40% by volume Bi alloy, and the specific friction amount becomes extremely small particularly at a friction distance of 200 to 600 m. FIG. 3 shows 580 ° C. (a) and 640 ° C.
It is an optical micrograph which shows the structure | tissue of the Al-40 volume% Bi alloy each sintered in (b). FIG.
It is an optical microscope photograph which shows the structure of 0 volume% Bi-15 volume% (Cu-graphite) alloy.

The Al-Bi-Mg sintered bearing alloy of the present invention has a Bi content of 3 to 50% by volume (10.2 to 78.7).
%), More preferably 9 from the viewpoint of the specific wear amount.
-50% by volume, even more preferably 30-50% by volume
Range. At 30 to 50% by volume, the specific wear amount of ULBC4, which is a conventional representative lead bronze bearing alloy, is 4 × 10
It shows a specific wear amount equal to or less than ^-8 mm ³ / Nmm, and particularly shows the smallest specific wear amount when the Bi content is about 40% by volume. When the Bi content is increased beyond 40% by volume, the specific wear amount gradually increases. Therefore, the upper limit of the Bi content is preferably about 50% by volume. When the Bi content is less than 9% by volume to 3%, the specific wear amount increases, but still shows the same specific wear amount as compared with the conventional Al-Sn alloy and Al-In alloy, and the hardness is large. It has sufficient properties as a bearing alloy.

For comparison, the relationship between the Sn content and the specific wear (mm ³ / Nmm) was similarly determined for Al-Sn based sintered bearing alloys and Al-In based sintered bearing alloys manufactured in the same manner. As shown in FIG. Further, the In content and the specific wear amount (mm
³ / Nmm) is shown in FIG. Sintering temperature is 580 ℃
It is.

In the Al—Sn based sintered alloy, the most excellent composition is Sn content of about 12% by volume. In this case, the specific wear amount is about 4.5 × 10 ⁻⁸ mm ³ / Nmm, In the Al-In based sintered alloy, the most excellent composition is In.
Although the content is about 18% by volume, the specific wear amount in this case is about 6.2 × 10 ⁻⁸ mm ³ / Nmm.
Inferior to 1-Bi sintered bearing alloy.

Table 1 shows mechanical properties and relative densities of the Al—Bi based sintered bearing alloy, the Al—Sn based sintered bearing alloy, and the Al—In based sintered bearing alloy of the present invention. A of the present invention in which the content of bismuth is in the range of 9 to 30% by volume, and the remaining volume% is composed of 91% by weight of Al and 3% by weight of Mg.
It can be seen that the l-Bi based sintered bearing alloy has a bending strength equal to or higher than that of the Al-Sn based sintered alloy.

[0021]

[Table 1]

[0022]

EXAMPLE 1 Composition (Al-3% by weight Mg) -Bi 40% by volume (Al
The raw material powder was prepared at a predetermined mixing ratio so as to be -71 wt% Bi-0.9 wt% Mg) and then dry-blended. Next, these mixed powders were molded at 200 MPa, and then sintered at a temperature of 620 ° C. in a normal pressure Ar atmosphere.

FIG. 7 shows an X-ray diffraction pattern of the obtained sintered body. FIG. 8A shows the FeKα1 X-ray intensity detected from the worn surface. FIG. 9 shows the specific wear of the obtained sintered body in comparison with a conventionally known bearing alloy.

As shown in FIG. 7, Bi is finely and uniformly dispersed in Al in the Al—Bi based sintered alloy of the present invention. It can also be seen that a BiMg compound was formed. FIG. 9 shows that the Al—Bi based sintered alloy, Al
It can be seen that the -Si sintered alloy and the Al-In sintered alloy have better wear resistance than the GM metal and Gould metal which are practical alloys.
l-Bi based sintered alloys are available in four types of lead bronze (LBC4) or Al
It can be seen that the specific wear amount is smaller than that of the -Pb alloy (SUT METALA).

Example 2 Sintering was performed under the same conditions as in Example 1 except that the raw material powder was prepared so that the Bi content in the sintered alloy was 9% by volume. FIG. 7 shows an X-ray diffraction pattern of the obtained sintered body. Bi is finely and uniformly dispersed in Al, and Bi ₃ Mg ₂ is generated in a sintered body having a Bi content of 9% by volume.
Bi for 0 volume% sintered body It can be seen that Mg has been generated. Further, as shown in Table 1, when Bi is 9% by volume, the bending strength shows a very large value of 209.1 MPa.

Example 3 A green compact was produced under the same conditions as in Example 1 except that the raw material powder was prepared so that the Bi content in the sintered alloy was 21% by volume. Sintered at 640 ° C.
(A) and (b) of FIG. 10 show optical microscope micrographs of the obtained sintered body. The black part of the photo is Bi, Bi
It can be seen that Ni is finely and uniformly dispersed in Al, and that the lower the sintering temperature, the softer metal Bi is finely and uniformly dispersed in Al in the form of a mesh.

EXAMPLE 4 An alloy composition of 15% by volume of the total of copper and graphite, 40% by volume of bismuth and the remaining 45% by volume of 97% by weight of Al and 3% by weight of Mg (Al-69.3% by weight) % B
i-0.6 wt% Mg-4.8 wt% Cu-4.8 wt% graphite)
Sintering was performed under the same conditions as in Example 1.

FIGS. 8A and 8B show the X-ray intensity FeKα1 detected from the worn surface. FIG. 9 shows the specific wear compared with a conventionally known bearing alloy. (A) of FIG.
Comparing with (b), it can be seen that the sintered alloy mixed with the copper-plated graphite powder has a low partner attack. From FIG.
Al-Bi-Mg-Cu-graphite sintered alloy of the present invention,
Alloy containing graphite powder added to Al-Pb based sintered alloy (SUT
It can be seen that the specific wear amount is equivalent to that of METALB).

Comparative Example 1 An Al-Sn sintered alloy was prepared under the same conditions as in Example 1 except that the raw material powder was prepared so that the composition was Al-27.2% by weight Sn-1.7% by weight Mg. Made. As shown in FIG. 9, the specific wear amount was 4.5 × 10 ⁻⁸ mm ³ / Nmm.

Comparative Example 2 An Al-In sintered alloy was prepared under the same conditions as in Example 1 except that the raw material powder was prepared so that the composition was Al-32.7% by weight In-2.0% by weight Mg. Made. The specific wear amount was 6.3 × 10 ⁻⁸ mm ³ / Nmm as shown in FIG.

[0031]

The Al-Bi based sintered bearing alloy of the present invention
Since performance equivalent to Al-Pb based sintered alloy is obtained,
It is a new sintered bearing alloy that does not use Pb, which is a problem from the viewpoint of environmental issues, and can meet the needs of the industry.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the Bi content and the specific wear amount of an Al—Bi based sintered bearing alloy of the present invention for each sintering temperature.

FIG. 2 is a graph showing a relationship between a friction distance and a specific wear amount of the Al—Bi based sintered bearing alloy of the present invention.

FIG. 3 is a photograph substituted for a drawing showing an optical microscope structure of the Al—Bi based sintered bearing alloy of the present invention.

FIG. 4 shows Al-Bi- (Cu-Gr) of the present invention.
4 is a photograph as a drawing substitute showing an optical microscope structure of a system-based sintered bearing alloy.

FIG. 5 is a graph showing the relationship between the Sn content and the specific wear amount of a conventionally known Al—Sn sintered bearing alloy.

FIG. 6 is a graph showing the relationship between the In content and the specific wear amount of a conventionally known Al—In sintered bearing alloy.

FIG. 7 is an X-ray diffraction pattern diagram of the sintered alloy obtained in Example 1 and Example 2.

FIG. 8 is a graph showing the FeKα1 X-ray intensity detected from the worn surface in Example 1 and Example 4.

FIG. 9 is a graph showing a comparison between the specific wear of the Al—Bi based sintered bearing alloy of the present invention and a conventionally known bearing alloy.

FIG. 10 is a photograph substituted for a drawing showing an optical microscope structure of the Al—Bi based sintered bearing alloy of Example 3.

Claims (8)

[Claims] 1. A method according to claim 1, wherein bismuth is 3 to 50% by volume and the remaining 97 to 50% by volume is made of Al.
l-Bi based sintered bearing alloy. 2. An Al-Bi-based sintered bearing alloy, characterized in that bismuth is 3 to 50% by volume and the remaining 97 to 50% by volume is composed of 97% by weight of Al and 3% by weight of Mg. 3. Bismuth is 3 to 50% by volume, the total amount of copper and graphite is 15% by volume or less, and the balance is 91% by volume.
Al- characterized in that more than 35% by volume is made of Al
Bi-based sintered bearing alloy. 4. Bismuth is 3 to 50% by volume, the total amount of copper and graphite is 15% by volume or less, and the balance is 91% by volume.
An Al-Bi-based sintered bearing alloy, characterized in that the super-35% by volume is composed of 97% by weight of Al and 3% by weight of Mg. 5. The Al—Bi based sintered bearing alloy according to claim 1, wherein bismuth is 9 to 50% by volume. 6. The Al—Bi based sintered bearing alloy according to claim 1, wherein bismuth is 30 to 50% by volume. 7. A method according to claim 1, wherein the raw material powders are mixed at a predetermined ratio so as to obtain the alloy composition according to claim 1, compacted, and sintered at 520 ° C. to 640 ° C. in an inert atmosphere under normal pressure. The method for producing an Al-Bi-based sintered bearing alloy according to any one of claims 1 to 5, wherein 8. The method according to claim 6, wherein copper-plated graphite powder is used as a raw material.