JP7214451B2 - Copper alloy - Google Patents

Description

TECHNICAL FIELD The present invention relates to a copper alloy used for sliding members and the like.

Conventionally, beryllium copper is known as a high-strength copper alloy, but beryllium copper has problems that beryllium compounds are toxic and cost is high. On the other hand, copper-nickel-tin (Cu-Ni-Sn)-based copper alloys, which are non-toxic and whose strength can be improved by age hardening treatment, have attracted attention.

For example, it contains 3.0 to 25.0% by mass of nickel, 3.0 to 9.0% by mass of tin, and 0 to 0.10% by mass of phosphorus, with the balance being copper and unavoidable impurities. Copper alloys have been proposed. It is also stated that by using such a copper alloy, it is possible to provide a copper alloy with improved strength and conductivity in a well-balanced manner (see, for example, Patent Document 1).

Japanese Patent No. 6210572

However, in the copper alloy described in Patent Document 1, although nickel and tin can ensure strength, there is a problem that sufficient machinability and slidability cannot be ensured.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a copper alloy having high strength and excellent machinability and slidability.

In order to achieve the above object, the copper alloy according to the present invention contains 4.0 to 20.0% by mass of nickel, 4.0 to 20.0% by mass of tin, and 0.1 to 1.0% by mass of sulfur. % by mass, and the remainder is copper and unavoidable impurities.

ADVANTAGE OF THE INVENTION According to this invention, while having high intensity|strength, the copper alloy which can be compatible with the excellent machinability and slidability can be provided.

4 is a graph showing the relationship between the friction coefficient and the friction distance in a ball-on-disk test of the copper alloys of Example 1 and Comparative Example 1. FIG. FIG. 2 is a diagram showing shavings of the copper alloy of Example 1; FIG. 10 is a diagram showing shavings of the copper alloy of Comparative Example 1;

The copper alloy in this embodiment will be described below.

The copper alloy of the present embodiment contains predetermined amounts of nickel, tin, and sulfur (S), and the balance is copper and unavoidable impurities.

In the copper alloy of the present embodiment, it is necessary to contain 4.0 to 20.0% by mass of nickel from the viewpoint of ensuring strength. If it is less than 4.0% by mass, the material strength is lowered. Moreover, when it is more than 20.0% by mass, it may not be suitable for casting. The nickel content is preferably 4.0 to 19.0% by mass, particularly preferably 4.0 to 16.0% by mass.

Tin is intended to improve the strength of the copper alloy through a synergistic effect with nickel. The copper alloy of this embodiment must contain 4.0 to 20.0% by mass of tin. If it is less than 4.0% by mass, the material strength is lowered. On the other hand, when it is more than 20.0% by mass, the thermal conductivity is lowered, making it unsuitable for use in high-temperature environments. The tin content is preferably 4.0 to 18.0% by mass, particularly preferably 4.0 to 15.5% by mass.

Sulfur also reacts with copper, iron (Fe), and the like to form sulfides. This sulfide, like lead, graphite, and molybdenum disulfide, has solid lubricity, lowers the coefficient of friction, improves compatibility, and provides good slidability in sliding conditions. . In addition, due to the presence of these sulfides, the copper alloy becomes short chips that are shredded during cutting, so it is difficult for them to wrap around the blade used for cutting. As a result, Machinability can be improved.

The copper alloy of this embodiment must contain 0.1 to 1.0% by mass of sulfur.
If the sulfur content is less than 0.1% by mass, the aforementioned machinability and slidability effects may not be sufficiently obtained. On the other hand, if it exceeds 1.0% by mass, it becomes unsuitable for casting. From the metal phase diagram of Cu—S, it is preferable that the content is 0.6% by mass or less in order to exhibit sufficient sliding performance.

That is, since the copper alloy of the present embodiment contains 0.1 to 1.0% by mass of sulfur, sulfides are dispersed in the alloy as a solid lubricant that improves sliding characteristics. It will be. In addition, sulfides are dispersed in the copper alloy, and these sulfides act as chip breakers during cutting, thus improving machinability.

The copper alloy of this embodiment may contain iron. Iron forms sulfides, together with sulfur, which improve the slidability of the copper alloy. From the viewpoint of forming sulfides necessary for ensuring slidability, the content of iron is preferably 0.03% by mass or more. Also, the content of iron is preferably 1.0% by mass or less. This is because if the iron content exceeds 1.0% by mass, the slidability may not be ensured.

The copper alloy of this embodiment may contain phosphorus (P). Phosphorus exhibits the effect of deoxidizing the molten copper alloy according to its content. Furthermore, when sintering the powder produced by the atomization method, if the impurities present at the boundaries between the particles of the powder to be sintered are reduced by deoxidation, obstacles during sintering will be reduced. The effect of improving the In order to fully exhibit these effects, it is preferable to contain 0.01% by mass or more. On the other hand, if it exceeds 0.5% by mass, the performance as a sliding member may be impaired, which is not preferable. That is, in the copper alloy of this embodiment, the phosphorus content is preferably 0.01 to 0.5% by mass.

The copper alloy of this embodiment may contain zinc (Zn). Zinc further improves the strength of the copper alloy. When the content of zinc exceeds 20.0% by mass, the strength may slightly decrease compared to the case where the content is less than 20% by mass. That is, in the copper alloy of the present embodiment, when zinc is contained, the content of zinc is not particularly limited, but from the viewpoint of maintaining excellent strength, it is 20.0% by mass or less (however, 0 mass %).

The copper alloy of the present embodiment contains impurities that are inevitably contained in addition to the above elements and copper, which is the residual, to the extent that the characteristics of the copper alloy are not impaired. good too.

These impurities are components that are unavoidably included when recycled materials are used in consideration of the environment, or when facilities are shared for the preparation of the copper alloy and the casting of the sliding members. Of course, from the point of view of physical properties, the content of this impurity is preferably as small as possible, and it is more preferable to contain no impurity, but it is difficult to reduce the content to zero.

For example, as the impurity, the amount of cobalt contained in the copper alloy is preferably 0.1% by mass or less. This is because if it exceeds 0.1% by mass, the quality of the casting deteriorates.

As the impurity, the amount of molybdenum contained in the copper alloy is preferably 0.1% by mass or less, and more preferably less than the detection limit. When molybdenum is contained in copper alloys as molybdenum disulfide combined with sulfur, the molybdenum disulfide is oxidized during the preparation of the copper alloy, during the manufacture of the sliding member, and during the use of the sliding member. This is because an undesired amount of sulfur is generated, which may corrode the copper alloy.

Moreover, as this impurity, the amount of silicon (Si) contained in the copper alloy is preferably 0.1% by mass or less.

The mass mixing ratio of each component specified in the present invention is not the mixing ratio of the raw materials in the manufacturing stage, but the mass mixing ratio of the components in the alloy obtained by melting the raw materials.

In addition, the remainder of the copper alloy is copper, and the alloy containing the above elemental components can be obtained by a general copper alloy production method, and the sliding member made of this copper alloy is produced by a general casting method. can be manufactured by

Examples of sliding members using the copper alloy of this embodiment include bushes, bearings, liners, and plates.

Hereinafter, the copper alloy of the present invention will be described with specific examples. However, the present invention is not limited to these examples.

<Ball-on-disk test>
Each component of Example 1 and Comparative Example 1 shown in Table 1 was blended, heated to 1200° C. to melt, and cast into a copper alloy using a mold. After that, in order to increase the strength, heat treatment (solution treatment: held at 800 ° C. for 1 hour, and aging treatment: held at 350 ° C. for 3 hours and 15 minutes) was performed, and machining was performed to increase the outer diameter to 44 mm, the inner diameter to 19 mm, and the thickness. A doughnut-shaped disc with a thickness of 8.5 mm was prepared. The friction surface was finished with #80 waterproof paper.

Next, on each of the fabricated disks of Example 1 and Comparative Example 1, balls (3 pieces) of 6.35 mm diameter made of chromium bearing steel (SUJ2) were placed at equal intervals (120° intervals on a circumference of 34 mm diameter). ). The ball used had a flat polished tip so as to come into surface contact with the disk.

Next, the jig in which the balls were arranged was fixed to the driving shaft installed in the upper part of the test device, and the disk was fixed to the rotary shaft containing the friction torque measuring mechanism located in the lower part of the test device.

Next, while the disc and the ball are in surface contact, the disc is pushed up with a weight of 1 kg via a lever to press the contact surface between the disc and the ball with a pressure of 1.0 MPa, thereby reducing the pressure to zero. It was rotated at a friction speed of .2 m/s.

Next, in each disk of Example 1 and Comparative Example 1, the friction force was obtained from the value of the friction torque, and the friction coefficient was calculated using this value. The rotational distance (that is, the frictional distance [m]) until the value at which the mobility decreases) was measured. The above results are shown in FIG.

As shown in FIG. 1, the copper alloy of Example 1 containing 6.37% by weight nickel, 6.14% by weight tin, and 0.31% by weight sulfur is comparable to the copper alloy of Comparative Example 1 containing no sulfur. It can be seen that the friction distance until the coefficient of friction reaches 0.5 is longer than that of the alloy, and the slidability is excellent.

<Cutting test>
For each copper alloy of Example 1 and Comparative Example 1 described above, a desktop lathe (manufactured by Cosmo Machinery Co., Ltd., trade name: JL-200) and a carbide cutting tool (manufactured by Sumitomo Electric Industries, Ltd., trade name : CCGT060202MN), perform lathe processing under the conditions of cutting speed of 300 rpm, depth of cut of 0.1 mm, and feed rate of 0.02 mm/rev, and judge machinability based on the shape of the chips. bottom. 2 shows cutting chips of the copper alloy of Example 1, and FIG. 3 shows cutting chips of the copper alloy of Comparative Example 1. As shown in FIG.

As shown in FIGS. 2 and 3, the copper alloy shavings of Comparative Example 1 are continuous without interruption and are inferior in machinability, but the copper alloy shavings of Example 1 are finely divided, It can be seen that it has excellent machinability.

<Hardness test>
The hardness of each disk of Example 1 and Comparative Example 1 used in the above-described ball-on-disk test was measured according to JIS Z 2244 (Vickers hardness test-testing method). The hardness was 302 HV, and the hardness of the disk of Comparative Example 1 was 317 HV. Therefore, it can be seen that the disk of Example 1 has the same high strength as the conventional disk containing no sulfur (the disk of Comparative Example 1).

(Examples 2 to 16, Comparative Examples 2 to 4)
First, the blending amounts of nickel, tin, sulfur, iron, phosphorus, and zinc are appropriately changed, and the remainder is blended as copper and unavoidable impurities, and the melting temperature was set to 1200° C., ingots were produced by the die casting method, samples of Examples 2 to 16 and Comparative Examples 2 to 4 were produced, and the components were analyzed. The above results are shown in Tables 2-4.

<Hardness test>
In each test piece of Examples 2 to 16 and Comparative Examples 2 to 4, in accordance with JIS Z 2244 (Vickers hardness test-test method), prescribed heat treatment conditions (solution treatment: held at 800 ° C. for 2 hours , aging treatment: under heat treatment conditions of holding at 350° C. for 4 hours), hardness (Vickers hardness) was measured. In addition, in each test piece of Examples 2 to 16 and Comparative Examples 2 to 4, the hardness before the heat treatment was also measured, and the increase in hardness after the heat treatment relative to the hardness before the heat treatment was based on the following formula (1). The rate (age hardenability) was calculated.

[Number 1]
Age hardenability [%] = [(Hardness after heat treatment - Hardness before heat treatment) / Hardness before heat treatment] × 100 (1)

In addition, in each test piece of Examples 2 to 4 and Comparative Examples 2 to 4, occurrence of casting defects was visually evaluated according to the following evaluation criteria. The above results are shown in Tables 2-4.
Casting defects did not occur: ○
A casting defect occurred: ×

As shown in Table 2, in Examples 2 to 4 in which the nickel content is 4.0 to 20.0% by mass, Comparative Examples 2 to 3 in which the nickel content is less than 4.0% by mass In comparison, it can be seen that both before and after the heat treatment, it has excellent hardness and high age hardenability.

In addition, in Comparative Example 4, since the nickel content is more than 20.0% by mass, it can be seen that casting defects occur.

In addition, as shown in Table 3, in Examples 5 to 10 in which the tin content was 4.0 to 20.0% by mass, both before and after the heat treatment had excellent hardness and high age hardenability. I understand.

Further, as shown in Tables 2 to 4, in Examples 2 to 15 in which the zinc content is 20.0% by mass or less, compared to Example 16 in which the zinc content is more than 20.0% by mass However, before and after the heat treatment, it can be seen that the hardness is excellent and the age hardening property is high.

In addition, in Example 16, in which the zinc content is more than 20.0% by mass, 4.0 to 20.0% by mass of nickel, 4.0 to 20.0% by mass of tin, and 0.0% by mass of sulfur are used. Since it contains 1 to 1.0% by mass, it can be seen that compared to Comparative Examples 2 and 3 in Table 2, it has excellent hardness and high age hardenability.

Also, in particular, a comparison of Example 5 (containing no zinc) and Example 11 (containing 2.97% by weight of zinc), and Example 6 (containing no zinc) and Example 12 (containing 3 zinc) .16% by mass), it can be seen that the hardness before and after the heat treatment is remarkably improved by containing 20.0% by mass or less of zinc.

As explained above, the present invention is particularly useful for copper alloys for sliding members that require high slidability and machinability.

Claims (1)

4.0 to 20.0% by mass of nickel, 15.21 to 20.0% by mass of tin, 0.1 to 1.0% by mass of sulfur , 0.03 to 1.0% by mass of iron, and A copper alloy containing 0.01 to 0.5% by mass of phosphorus, the balance being copper and inevitable impurities.

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