JPS58113335A - Wear resistant sintered copper alloy with self-lubricity and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a sintered Cu alloy with self-lubricity, superior workability and wear resistance by using graphite particles coated with Cu so as to provide a specified composition contg. graphite and Pb dispersed uniformly and finely in the Cu-Sn alloy matrix. CONSTITUTION:A sintered Cu alloy consisting of, by weight, 6-10% Sn, 4-11% Pb, 0.3-4% graphite and the balance essentially Cu is manufactured. At this time, in order to increase the bonding strength of graphite particles in the sintered alloy to the peripheral Cu-Sn alloy matrix, graphite particles coated with Cu are well mixed with other powdered starting materials. The powdered mixture is compacted to a prescribed shape and sintered. Thus, the sintered Cu alloy contg. graphite and Pb dispersed uniformly and finely in the Cu-Sn alloy matrix is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copper-based bearing material used in a thrust bearing for receiving the high-speed rotation of a turbine shaft of a turbocharger for a prime mover and the resulting thrust force. The present invention relates to a wear-resistant sintered steel alloy for round bearings and a method for producing the same.

Traditionally, Cu-S! has been used as a copper-based bearing material. 1 alloy (
Bronze) and Co-Sss-Pb alloys (lead bronze) are widely used, and copper-based bearing materials include those manufactured by melt casting and casting methods, and those manufactured by powder metallurgy methods. It is broadly classified into oil-impregnated bearings.

However, all conventional bearing materials of this type must be used with the lubrication effect of lubricating oil or lubricant, and even if lubricating oil or lubricant is not present, the lubrication effect of the lubricant may not be effective. If these expectations are not met, there is a problem that abnormal wear or seizure may occur, making the product unusable. Therefore, if the lubricating oil or lubricant cannot be fully used due to mechanical problems with the bearing part or other reasons, or if the lubricating effect is temporarily lost due to abnormal temperature rise during use, favorable results may not be obtained. I can't get it. Particularly in the case of sintered oil-impregnated bearings, there are severe temperature restrictions, and if the silver content is high, the lubricating effect of the lubricating oil cannot be expected, and abnormal wear and seizure are likely to occur.

This invention was made in view of the above circumstances, and can be used when lubricating oil or lubricant cannot be used, or when their lubrication effect cannot be expected, or when their lubrication effect is temporarily lost. It is an object of the present invention to provide a bearing material and a method for manufacturing the same, which cause less wear and prevent the occurrence of seizure.

That is, the bearing material of this invention is basically Cu-S.
This is a sintered steel alloy in which Pb and graphite are uniformly and finely dispersed in an alloy base using a powder metallurgy method, and the Pb particles and graphite particles provide self-lubricating properties. Graphite powder particles that are not added as a coalescing material are coated with Cu in advance, and added as copper-coated graphite particles to increase the holding power of the graphite particles to the Cu-Sn alloy base and improve wear resistance and workability. It was designed so that

Specifically, the sintered steel metal of this invention has a Sn6 to 1096
, Pb 4-11%, graphite 03-3%, balance substantially C
It is a sintered steel alloy consisting of u, and is characterized by finely and uniformly dispersing PB and graphite in the Cu'Sn alloy matrix. Furthermore, the manufacturing method of this invention includes:
So 6-10%, Pb4-11-1 lead 0.3-3
The remainder of Is1 is used to manufacture a sintered steel alloy consisting essentially of Cu. Among the above additive elements, graphite is added in the form of copper-coated graphite particles formed by coating the surface of fine graphite particles with CU. This method is characterized by obtaining an emotional copper alloy in which Pb and graphite are uniformly and finely dispersed.

The sintered steel alloy of the present invention and its manufacturing method will be explained in more detail below.

First, we will explain the reasons for limiting the ingredients of the sintered steel alloy of Koya's invention. 4. Sfi dissolves in Cu to increase the hardness of the matrix and improve wear resistance and mechanical properties, but 6. If it is less than 10%, the effect will be small, and if it exceeds 10%, the outflow pores will become large, leading to a decrease in mechanical strength.
. Therefore, Sm was set in the range of 6 to 10 m.

Pb provides a lubricating effect by dispersing it as fine particles, but its effect is small below 4'lb%.On the other hand, if it is added in excess of 11 cm, the lubricating effect does not improve any further1, and on the contrary, it The thickness was set in the range of 4 to 11 inches because it deteriorates the mechanical properties and the workability.

Graphite also has a remarkable effect of improving lubricity when dispersed in the form of fine particles, but if it is less than 0.3%, the effect is small, and on the other hand, if it exceeds 3%, not only will the lubricity not improve any further. However, it should be kept in the range of 0.3 to 3-3, since it would rather reduce the mechanical strength and worsen the workability.

In the sintered steel alloy of this invention having the composition as described above,
Sfi dissolves in Cu to form a Cm-8n alloy base, and Pb has an extremely small solid solubility limit in Cu.
It is dispersed in the Cu-Sn alloy matrix as Pb particles without solid solution in Cu, and Cm-
Dispersed in the Sn alloy base. Here, as the particle size of graphite particles increases, the workability decreases (Cu-
There is a risk that the holding force with the 8ta alloy base will be reduced and the wear resistance will be reduced during use as a bearing, that is, during sliding.

Therefore, it is desirable that graphite particles be as fine as possible, and specifically, it is desirable that graphite particles with a particle size of 8 μm be uniformly dispersed in a cross-sectional area ratio of 2 or more. In order to further increase the holding power to the Cu--Sn alloy matrix, it is desirable to add the graphite component of the sintering raw material in the form of copper-coated graphite particles whose surfaces are coated with Cu in advance, as will be explained in detail later. In addition, if the Pb particles are coarse, it will cause Pb segregation, leading to deterioration of workability and wear resistance, so it is desirable to make the Pb particles as fine as possible. ~8μm
It is desirable that the Pb particles are uniformly dispersed with a cross-sectional area ratio of 3s or more.

Next, a method for producing the above-mentioned sintered steel alloy will be explained.

First, to explain the raw material powder, among the above-mentioned additional elements, it is usually added as 8m FiCu -8m alloy powder, but even if SKI is added as a single metal powder, Srr will not be alloyed with Cu during sintering. Since this is done quickly, it may be added separately as a single metal powder.

pb is Co-8n-P since CuK hardly dissolves in solid solution.
The same effect can be obtained even if it is added as b alloy powder (however, Pb particles are dispersed in the alloy particles) or if Pb powder is added separately. However, in either case, the Pb particles need to be fine as described above. Graphite is usually added separately as graphite particles, but in this case, in order to increase the bonding force (particle retention force) between the graphite particles and the surrounding Cu-8m alloy base in the sintered body, graphite powder particles are added. It is preferable to cover the surface with copper in advance to form steel-coated graphite particles, and then use this by mixing it with other raw material powders.In this way, during the sintering process, the copper layer on the surface of the steel-coated graphite particles will spread over the surrounding area. The graphite particles are integrated with the Cu-E1m1m alloy powder, etc. to form a matrix, and the graphite particles and the surrounding matrix (Cm-am alloy base) are tightly bonded, so when sliding as a bearing, the graphite particles Peeling of particles is prevented as much as possible, and wear resistance and workability are significantly improved. In this case as well, the graphite particles need to be as fine as mentioned above from the time of addition.

When the above-mentioned raw material powders are mixed in a blending ratio corresponding to the composition of the sintered body to be finally obtained, and then compacted and sintered using a conventional method, Pb particles and graphite particles are formed. C
The desired sintered steel alloy is obtained which is finely and uniformly dispersed in the m-Pb alloy matrix. The sintering temperature is 700~
The temperature is preferably about 850°C.

Examples and comparative examples of this invention will be described below.

Example 1 44 parts by weight of a lead bronze alloy powder having a composition of C%M-10% Sn-10To Pb and a particle size of 1100 mesh, and a bronze alloy having a composition of Cu-10% 8n and a particle size of 1100 mesh. After mixing 50 parts by weight of powder and 6% of copper-coated graphite powder particles formed by coating graphite powder particles with a particle size of 8 μm or less with Cu at a gravity ratio of 50%, and compacting into a predetermined shape, Sintering was performed at 800° C. for 30 minutes in an ammonia decomposition gas atmosphere. The density of the obtained sintered body was 7.8c, and the composition of the sintered body was Cu-9,4To8n-
The result was 4.4% Pb-3% graphite.

In this sintered body, graphite particles with a particle size of 8 μm or less are uniformly dispersed in a cross-sectional area ratio of 2 or more, and Pb particles with a particle size of 8 μm or less are uniformly dispersed in a cross-sectional area of 3 or more. It has been confirmed that they are distributed in circles.

Example 2 The composition is Cu-10'lk So and the particle size is 110
89.5 parts by weight of bronze alloy composition premix powder of 0 mesh, and 10 parts by weight of sPb powder having a particle size of 15 μm or less and having a particle size of 8 μm or less for at least 50 seconds;
The mixture was mixed with 0.5 parts by weight of graphite having a particle size of 8 μm or less, compacted into a predetermined shape, and then sintered at 750° C. for 30 minutes in a propane converted gas atmosphere.

The density of the obtained burnt body was 7.5 -, which was 4! Composition of nine sintered body tfcts-8,95*St+-101Pb-
There was 0,5-graphite. In this sintered body,
Graphite particles with a particle size of 8 μm or less are uniformly dispersed in a cross-sectional area ratio of 04 µm or more, and Pb particles with a particle size of 8 μl or less are uniformly dispersed in a cross-sectional area ratio of 3 s or more.

Comparative Example 1 A lead bronze alloy powder having the same composition and particle size as the lead bronze alloy powder used in Example 1 was molded into a predetermined shape, and after death, it was sintered at 800°C for 30 minutes in an ancholynia decomposition gas to form a round shape. The density of the obtained sintered body was 7.8 i/d. Note that the lead bronze alloy powder described above had poor formability, so it was granulated in advance before use.

Comparative Example 2 90 parts by weight of bronze alloy powder with a composition of Cu-10% am and a particle size of -100 metric, 9 parts by weight of the powdered lead powder used in Example 2, and a particle size of -150 metric, (0,10
4fi or less) was mixed with 1 part by weight of coarse graphite powder, compacted into a predetermined shape, and then sintered at 75L1°C for 30 minutes in a propane modified gas atmosphere. The density of the obtained sintered body was 7.59/d, and the composition of the sintered body was Cu.
-9T Sn -9T Pb -1T graphite.

Comparative Example 3 90 parts by weight of a bronze alloy powder having a composition of Cu-10% Sn and a particle size of 1100 mesh and 10 parts by weight of the atomized PB powder used in Example 2 were mixed and pressed into a predetermined shape. After powder molding, it was sintered at 750° C. for 30 minutes in a propane converted gas atmosphere. The density of the obtained sintered body was 7.5 y/cd, and its composition was Cu -9% Sn -10%
Pb gave 1>.

The formulations of the raw material powders in each of the above Examples and Comparative Examples are summarized in Table 1. In addition, the strength, stiffness, and wear resistance of the sintered bodies obtained in each Example and each Comparative Example were examined, and the results shown in Table 2 were obtained. However, for the rigidity test, the sintered body was drilled under the conditions described in F, and the rigidity was evaluated based on the presence or absence of chips.

Sample shape: 25X25XlO- rectangular parallelepiped Drill: S
KH-9, φ2.5N Rotation speed: 1200 rpm Feed rate: 1 m%'sec In addition, the wear test was carried out using an Okoshi type wear tester for both the state in which the sintered body was impregnated with oil and the state in which it was not impregnated. I went with the conditions.

Sample shape: 25X25XlOsg rectangular parallelepiped Sliding speed:
4.26 m/sec Load: 2.1 kg Sliding distance 111:600■ Compatible material: SUJ-2 Oil-impregnated oil: Mobile No. 30 (product name) Mouth 1: Mixture of raw material first wood (unit w1 inch) jA2 As shown in Table 2, the sintered bodies according to the examples of the present invention did not exhibit a small amount of wear when impregnated with oil, compared to those of comparative examples, but also exhibited a decrease in the amount of wear even when not impregnated with oil. It is clear that it has excellent self-lubricating properties, as there is little seizure or seizure. It is also clear that it has high strength and excellent workability (rigidity). Especially Example 1
Graphite is added as copper-coated graphite particles,
It is clear that in this case the wear resistance is significantly superior. In Comparative Example 2, the composition of the sintered body is within the scope of the present invention, but the graphite particles are -15"0mets/, (0,104
- and below), and in this case, the amount of wear is much greater than in the example, and from this it is clear that the graphite particles need to be fine.

As is clear from the above explanation, the sintered steel alloy of this invention is
Since the graphite particles and PB particles of the proper cover are finely and uniformly dispersed in the Cu-So base, it has excellent self-lubricating properties, and therefore, it is possible to use lubricating oil or lubricant as a bearing for mechanical or other reasons. Even when used in cases where the lubricating effect cannot be expected, or where the lubricating effect is temporarily lost, there is little risk of abnormal wear or seizure, and of course... Even when using lubricant and side beak material in combination, and the lubrication effect of these can be expected, the amount of wear is significantly lower than that of conventional products, improving durability, and the strength is lower than that of conventional products. The length of each building is FgT, which has excellent workability.
It has the following.

In addition, in the method for producing the sintered copper alloy of the present invention, the graphite component of the raw material is added as copper plate-graphite particles.
The bonding force (particle retention force) between the graphite particles and the base is increased, and the effect of further improving the viscous abrasion resistance and processability is obtained.

Applicant: Toyota Automobile East Kogyo Co., Ltd. Nippon Powder Alloy Co., Ltd.

Claims (4)

[Claims] (1) So 6-10% (weight%, same below)
, pb4-115G, graphite 0.3-31 balance substantially C
A self-lubricating, wear-resistant sintered steel alloy, which is a sintered copper alloy consisting of u, characterized in that PB and graphite are uniformly and finely dispersed in the Cu--Sn alloy matrix. (2) The sintered steel alloy according to claim 1, wherein Pb particles having a particle size of 3 to 8 μm are uniformly dispersed in a cross-sectional area ratio of 3 or more as Pb in the Cu-Sn alloy matrix. . (3) The sintered steel according to claim 1, wherein graphite particles having a grain size of 8 μm or less are uniformly dispersed at a cross-sectional area ratio of 2 or more as the graphite in the Cu-8t* alloy matrix. alloy. (4) Sn6~10chi, Pb4~11-1 graphite 0.3
~3-1 To produce a sintered steel alloy with the remainder substantially consisting of Cu, graphite among the above-mentioned additive elements is added as steel-coated graphite particles formed by coating CI on the surface of fine graphite particles. A method for producing a self-lubricating wear-resistant sintered steel alloy, characterized in that Pb and graphite are uniformly and finely dispersed to obtain a sintered steel alloy.