KR930006211B1 - Copper base alloy superior in resistances to seizure, wear and corrosion suitable for use as material of sliding member - Google Patents

Abstract

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Description

Copper-based alloys with excellent corrosion resistance, wear resistance, and corrosion resistance suitable for use as sliding member materials

1 is a graph showing the internal testing method in relation to Table 4,

2 is a graph showing the internal test results,

3 is a graph showing the wear resistance test results,

4 is a graph showing the corrosion resistance test results.

FIELD OF THE INVENTION The present invention relates to a copper-based alloy having excellent stiffness, abrasion resistance and corrosion resistance suitable for use as a sliding member, in particular a sliding member material such as a turbocharger's floating bush bearing.

Generally, the following materials (1) to (3) are known as materials for floating bush bearings in turbochargers: (1) free cutting brass (JIS H 3250), (2) lead bronze ( JIS H 5115) and (3) low friction-tensile brass described in JP-B2-53-44135 and JP-B2-56-11735 of the present applicant.

However, when the alloy 1 is used under economic lubrication conditions, the sintering resistance and wear resistance are inferior, and the alloy 2 cannot provide sufficiently high corrosion resistance when used in lubricating oil deteriorated at a high temperature. The alloy 3 does not exhibit satisfactory high baking resistance because it is difficult to increase the lead content due to its matrix having a fine structure of the α- and β-phase mixtures or the β-phase alone.

In recent years, engine supercharging has progressed rapidly, and floating bush bearings used in turbochargers installed in internal combustion engines have been operated under severe conditions such as ambient temperature, lubricant supply and lubricant degradation. need.

Generally, floating bush bearings are heated to a high temperature, for example 400 ° C., due to the heat conduction from the turbine, so depending on the nature and temperature of the oil, the sulfur contained in the lubricating oil reacts with the copper in the bearing metal to make copper sulfide (CuS) is formed to form a blackide layer composed mainly of CuS on the surface of the bearing metal. The blackened layer grows gradually over long periods of use and peels off the bearing surface, severely damaging the bearing friction of the floating bush bearing.

Moreover, conventional bearing materials cannot provide satisfactory firing resistance under dry-up conditions when lubricating oil is stopped at a high temperature of 300 ° C or higher. Specifically, a turbocharger equipped with a gas turbine impeller driven by high temperature and high pressure exhaust gas energy and a compressor driven by a turbine impeller is idle due to its inertia even after stopping the engine to stop supplying pressurized lubricant. (idle) Thus, the turbocharger idles for a while without the cooling and lubricating effect caused by the lubricating oil. As a result, the heat energy accumulated in the high temperature turbine housing is transferred to the low temperature region to raise the temperature of the bearing portion. Therefore, the bearing needs to have high plastic resistance in the dry-up state at high temperature.

To date, lead-brass systems containing copper, lead and tin as the main component and free-cut brass containing copper, zinc and lead as the main component have been widely used as floating bush bearing materials for turbochargers. However, a floating bush bearing of a lead-brass alloy promotes the formation of a black oxide layer by the reaction between sulfur in lubricating oil and copper in brass under dry-up conditions at a high temperature of about 300 ° C. and wear of the bearing surface rapidly occurs. In contrast, the free-cutting brass alloy exhibits excellent corrosion resistance, but shows poor inferior affinity for lubricating oil after lubrication stop, resulting in relatively premature burning or fusion wear.

It is an object of the present invention to provide excellent resistance to abrasion, fire and corrosion and to withstand the use of harsh conditions, such as those operating under high sliding speeds and high temperatures under the high corrosion conditions generally encountered by turbocharger bearings. It is to provide a novel copper-based alloy suitable for use as the material of the member.

The object of the invention described above is achieved according to the invention by one of the alloys (a) to (d) as follows.

(a) 1.0-3.5 wt% manganese, 0.3-1.5 wt% silicon, 10-25 wt% zinc, 5-18 wt% lead and the remainder consisting of copper and unavoidable impurities, the lead being an alloy structure A copper-based alloy which is uniformly dispersed throughout and has excellent microcorrosion resistance and corrosion resistance, suitable for use as a material of a sliding member, having a microstructure composed only of α-phase.

(b) 1.0 to 3.5 weight percent manganese, 0.3 to 1.5 weight percent silicone, 10 to 25 weight percent zinc, 5 to 18 weight percent lead, 0.02 to 1.5 weight percent magnesium and 0.1 to 1.5 weight percent telll At least one selected from the group consisting of copper and at least one selected from 0.1 to 1.5% by weight of tellurium and the remaining wastes are composed of copper and unavoidable impurities, and the lead is uniformly dispersed throughout the alloy structure. A copper-based alloy having excellent corrosion resistance, abrasion resistance, and corrosion resistance, suitable for use as a material of a sliding member, having a microstructure having a microstructure with only the α-phase.

(c) 1.0 to 3.5 weight percent manganese, 0.3 to 1.5 weight percent silicon, 10 to 25 weight percent zinc, 5 to 18 weight percent lead, 0.5 to 3.0 weight percent nickel and 0.3 to 3.0 weight percent aluminum At least one selected from the group consisting of copper and unavoidable impurities, the lead being uniformly dispersed throughout the alloy structure, and having a microstructure in which the matrix is composed only of the α-phase. Copper-based alloy with excellent buoyancy and corrosion resistance.

(d) 1.0 to 3.5 weight percent manganese, 0.3 to 1.5 weight percent silicone, 10 to 25 weight percent zinc, 5 to 18 weight percent lead, 0.02 to 1.5 weight percent magnesium and 0.1 to 1.5 weight percent telll At least one selected from thromium, from 0.5 to 3.0% by weight of nickel and from 0.3 to 3.0% by weight of at least one selected from aluminum and the remainder consists of copper and unavoidable impurities, the lead being uniformly dispersed throughout the alloy structure, A copper-based alloy excellent in calcination resistance, abrasion resistance and corrosion resistance suitable for use as a material of a sliding member, in which the matrix has a microstructure only in the α-phase.

The action of the alloy components and the reasons for limiting the content of these components are described below.

(1) Zinc (Zn): 10 to 25% by weight

Zinc is a component that gives strength, wear resistance and corrosion resistance to lubricants. The preferred content of this component depends on the zinc equivalents of the different starbursts, but if the zinc content is less than 10% by weight, it should not be less than 10% by weight because the above-mentioned effects do not occur. The addition amount of lead (Pb) which is usually added in order to improve fire resistance is undesirably limited when the structure has a mixed phase of? Therefore, in general, the alloy of the present invention should have a single-phase structure of the α-phase. In order to ensure the microstructure of the α-phase alone and to minimize the content of lead in the α-phase (eg 5% by weight), the maximum content of zinc should be 25% by weight.

(2) Manganese (MN): 10 to 3.5% by weight

Manganese reacts with silicon (Si) to form an intermetallic compound Mn ₅ Si ₃ having excellent sliding properties, thereby contributing to improvement of wear resistance and baking resistance, and preventing plastic flow of the matrix during intermetallic contact. In order to obtain a recognizable effect, the content of manganese should be at least 1.0% by weight. On the contrary, exceeding 3.5% by weight is not preferable because it causes saturation of the effect and the alloy is brittle.

(3) Silicon (Si): 0.3 to 1.5% by weight

As mentioned above, the silicon is reacted with manganese to form the intermetallic compound Mn ₅ Si ₃ which contributes to the improvement of wear resistance and fire resistance. The silicon content is determined according to the content of Mn ₅ Si ₃ obtained. The total silicon is changed to the compound described above when the ratio of manganese and silicon is 1: 0: 3 as the weight ratio. Therefore, the silicon content should be at least 0.3% by weight. When the addition of silicon exceeds the upper limit of 1.5% by weight, the crystallization of the free silicon becomes excessive and the alloy is easily broken.

(4) lead (Pb): 5 to 18% by weight

Lead is self-lubricating and easily melted by frictional heat and spreads on sliding surfaces to form thin films of several microns in thickness, thereby significantly improving corrosion resistance and obtaining excellent machinability. In order to form a thin film of lead several microns thick, the lead content requires at least 5 weights or more. On the contrary, since the strength of the alloy decreases as the content of lead increases, the maximum lead content is 18% by weight, and therefore the lead content is in the range of 5-18% by weight.

(5) magnesium (Mg): 0.02 to 1.5% by weight

Magnesium is an effective ingredient for uniformly dispersing lead and strengthening the matrix. These effects do not appear when the magnesium content is 0.02% by weight or less. On the contrary, when the magnesium subscript exceeds 1.5% by weight, crystallization of the intermetallic compound of magnesium and lead is excessive, thereby impairing the lubrication effect caused by lead. For this reason, the content of magnesium is limited to the range of 0.02 to 1.5% by weight.

(6) Teltium (Te): 0.1 to 1.5% by weight

Teltrium promotes uniform dispersion of lead even in small amounts, improves the toughness and calcining resistance of the alloy and at the same time improves the corrosion resistance. However, these effects do not appear when the tellrium content is 0.1% by weight or less. In contrast, if the addition of more than 1.5% by weight, the cost is uneconomically increased, but no further effect. Therefore, the addition amount of tellurium is in the range of 0.1 to 1.5 weight%.

(7) Nickel (Ni): 0.5 to 3.0% by weight

Nickel strengthens the matrix to improve the strength of the alloy, while also improving wear resistance. Nickel also raises the crystallization temperature to prevent coarsening of the crystal grains during hot firing. However, these effects do not appear when the nickel content is 0.5% by weight or less. In contrast, when nickel is added in excess of 3% by weight, fatigue strength and impact resistance of the alloy are severely impaired. For this reason nickel is in the range of 0.5 to 3.0% by weight.

(8) Aluminum (Al): 0.3 to 3.0% by weight

Aluminum also contributes to the strengthening of the matrix. However, this effect also does not appear when the aluminum content is 0.3% by weight or less, on the contrary, when the aluminum content exceeds 0.3% by weight, it has a brittle property and causes coarsening of crystal grains. For this reason, the aluminum content is in the range of 0.3 to 3.0% by weight.

Several embodiments of the inventive alloy are described below with reference to the drawings.

EXAMPLE

[Test Example 1 (alloy of the present invention)]

No. shown in Table 1 Alloys having a composition of 1 to 9 are prepared by a continuous casting method, and a bar having a diameter of 35 mm is formed by extrusion and drawing, and then the bars are appropriately processed to prepare specimen pieces for quench test, abrasion test and corrosion test.

The test conditions performed with these test pieces are shown in Tables 2 to 4 and FIG. Representative corrosion test results are shown in FIG.

[Test Example 2 (Primary Alloy)]

No. shown in Table 1 Continuous casting of conventional alloys with small compositions of 10 to 13. Extrusion and drawing processes form a bar with a diameter of 35 mm. The same test as in the test piece of Test Example 1 was carried out. These test conditions are shown in Tables 2 to 4 and FIG. 1, and the test results are shown in FIGS. 2 to 4.

Several tests were carried out on alloy bars produced by continuous casting, but it can be seen that the same advantages can be obtained by using test pieces of alloys produced by other casting methods such as stationary casting.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

TABLE 5

Evaluation of Test Results

(1) Compared to the baking test results shown in FIG. 2, the alloy of the present invention has a risk of burning up to a maximum load of 500 kg / cm 3 compared with conventional free cutting brass (No. 10) and high strength brass (No. 12 and 13). You can see that it can be used without it.

(2) As shown in Table 5 in the baking test, the alloy of the present invention was used in a baking test by turning on and off the supply of lubricating oil to the machine at a given speed using a real machine assembled with alloy bearings. The baking did not appear at all. Therefore, the alloy of the present invention exhibits very good performance as a sliding material, and thus satisfactory results are obtained when used as a material of a floating bush bearing.

(3) As can be seen in FIG. 3 showing the results of the abrasion test, the alloy produced according to the present invention was found to have less wear than the conventional alloy, thereby confirming that it had excellent wear resistance.

(4) The alloy according to the present invention has better corrosion resistance than the conventional alloy as can be seen in FIG. 4 showing the corrosion test results.

As described above, the copper-based alloy of the present invention is superior to the conventional corrosion-resistant, abrasion resistance, corrosion resistance and affinity, compared with the conventional alloy, these properties are particularly high performance and long life, such as sliding member of the turbocharger alloy of the present invention When used as a material of a sliding member that requires, excellent advantages are given.

Claims (4)

1.0-3.5% by weight manganese, 0.3-1.5% by weight silicon, 10-25% by weight zinc, 5-18% by weight lead and the remainder consisting of copper and inevitable impurities, the lead is uniform throughout the alloy structure A copper-based alloy having excellent corrosion resistance, abrasion resistance, and corrosion resistance, suitable for use as a material of a sliding member, having a dispersed structure and having a structure composed of only the α-phase. Selected from 1.0 to 3.5 weight percent manganese, 0.3 to 1.5 weight percent silicon, 10 to 25 weight percent zinc, 5 to 18 weight percent lead, 0.02 to 1.5 weight percent magnesium and 0.1 to 1.5 weight percent tellrium At least one species and the remainder are composed of copper and unavoidable impurities, the lead being uniformly dispersed throughout the alloy structure, and suitable for use as a material of the sliding member, having a structure consisting of only the α-phase matrix; Copper-based alloy, excellent in wear resistance and corrosion resistance. At least one selected from 1.0 to 3.5% manganese, 0.3 to 1.5% silicon, 10 to 25% zinc, 5 to 18% lead, 0.5 to 3.0% nickel and 0.3 to 3.0% aluminum One and the other consists of copper and unavoidable impurities, and the lead is uniformly dispersed throughout the alloy structure and suitable for use as a material of the sliding member, having a structure composed of only the α-phase matrix, which is suitable for wear-resistant and abrasion resistance And a copper-based alloy excellent in corrosion resistance. Selected from 1.0 to 3.5 weight percent manganese, 0.3 to 1.5 weight percent silicon, 10 to 25 weight percent zinc, 5 to 18 weight percent lead, 0.02 to 1.5 weight percent magnesium and 0.1 to 1.5 weight percent tellrium At least one selected from among at least one, 0.5 to 3.0 wt% nickel and 0.3 to 3.0 wt% aluminum, and the remainder consists of copper and inevitable impurities, the lead is uniformly dispersed throughout the alloy structure, and the matrix is α A copper-based alloy having a superior composition of abrasion resistance, abrasion resistance and corrosion resistance, suitable for use as a material of a sliding member, having a structure composed of phases.

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