DE4101620C2 - Copper alloy with better wear and corrosion resistance for use as a material for sliding and sliding elements - Google Patents

Description

The invention relates to a copper alloy with superior Resistance to wear and corrosion, for use as a material for a Sliding or sliding element is suitable. In particular is they are suitable for sliding or sliding elements, which at sharp sliding or sliding conditions are used, such as B. the Gleitbüchsenlager turbochargers.

For slide bushings of turbochargers are in Generally, the following materials (1) to (3) are known: (1) free cutting brass (JIS H3250), (2) lead bronze (JIS H5115) and (3) low-friction high-voltage brass, described in JP-B2-53-44135 and JP-B2-56-11735.

AT 198 959 describes bearing alloys which are known from 3 to 40% lead, 0.1 to 6% silicon, 0.1 to 5% manganese, 0.1 to 10% zinc and optionally 0.1 to 2% magnesium, 0.1 to 5% nickel and / or up to 2% aluminum and copper as balance consist.

DE-PS 7 64 372 describes a copper alloy for sliding elements, made up of more than 2 to 8% aluminum, 0.05 to 1.5% silicon, more than 3 to 10% manganese, 50 to 70% copper, up to 10% lead, 0.1 to 5% nickel and zinc as the remainder, where nickel may be missing as an ingredient.  

An alloy composition such as the invention corresponds, but is from the last-mentioned patents not to be removed; they also do not indicate the particular Corrosion resistance of the alloy according to the invention on.

The abovementioned alloy (1) is however in terms of their Resistance to galling wear and ver worse when they are under boundary lubrication is used. The above alloy (2) when used in decomposed lubricating oils at high Temperature does not reach a sufficiently high resistance. Finally, the alloy (3) can be compared with a fres Wear does not send a satisfying high resistance show what is due to the difficulty to increase their lead content. This is due to the fact too recirculate. that this alloy has a texture,  that of a mixture of α- and β-phases or only consists of the β-phase.

In recent years, there is a significant trend for super Charge motors emerged. Sliding sleeve bearings, the ver in turbocharged engines attached turbochargers ver be used, in harsh conditions, for example in terms of working temperature, feed rate of lubricating oil and the decomposition of lubricating oil, ar BEITEN.

In general, Gleitbüchsenlager to high tempera turen, z. B. 400 ° C or the like, heated, indicating the Heat transfer from the turbine is due. Therefore The sulfur contained in lubricating oils, depending on the Nature of the oil and the temperature, in addition to the copper of the bearing material to form copper sulfide (CuS) implement. This way, on the surface of the Bearing metal formed a black colored layer, the mainly composed of CuS. The black colored layer grows with prolonged use of the camp progressively and finally flips off the bearing surface where by the bearing function of Gleitbüchsenlagers schwerwie is impaired.

Furthermore, conventional storage materials at Ein to dry, d. H. if lubrication with the lubricating oil at high temperature such as 300 ° C or higher is interrupted, no satisfactory resistance to one resulting in eating wear. This is how it works - to be more specific explain - a turbocharger with a gas turbine wing or propeller powered by the energy of the exhaust gas Temperature and high pressure is driven, and a Compressor powered by the turbine propeller is due to its inertia after stopping the engine further, whereby the supply of pressurized  Lubricating oil is quit. Therefore, the turbocharger without Cooling and without resulting from the lubricating oil lubrication effects continue. As a result, the in the Turbi housing with high temperature accumulated heat energy in Transmitted areas of lower temperatures, thereby the temperature of the bearing part is increased. For this reason Therefore, the bearing must have a high resistance to a seizure in the dried state have high temperature.

So far, mainly lead-bronze systems, copper. Contain lead and tin as main components, and free Cutting brass alloys containing copper, zinc and lead as Main components included, as a material for Gleitbüch used by turbochargers. Slide bush bearing off Alloys of the lead ore system promote but in uner desirably the formation of black colored layers due to a reaction between the sulfur of the smear oil and the copper in the bronze at Eindrocknungsbedin conditions and at high temperature of 300 ° C or the like. This leads to rapid wear of the bearing surface. On the other hand show Free-cutting alloys from brass system, although they have a superior corrosion resistance have a poorer affinity to the Lubricating oil after completion of lubrication, resulting in a relatively early, guzzling or wear one Seizure leads.

The object of the invention is therefore a new copper alloy available as material for a Sliding or sliding element is suitable and the superior Properties in terms of wear, in particular the guzzling Wear and corrosion and has the sharp Be operating conditions, d. H. an operation with high slip speed and high temperature at highly corrosive  Conditions typically found in turbocharger bearings occur, can resist well.

This problem underlying the invention is achieved by one of the following inventive alloys (a) to (d) solved.

• a) One for use as a material for a sliding or Sliding element suitable copper alloy with superior Properties regarding eating wear, wear Resistance and corrosion resistance from 1.0 to 3.5 Wt% manganese, 0.3 to 1.5 wt% silicon, not less than 11.5 to 25% by weight of zinc, 5 to 18% by weight of lead, the remainder being aluminum and melting contamination, whereby the lead in the structure consisting of only α-phase is uniformly distributed throughout the alloy.
• b) One for use as a material for a sliding or Sliding element suitable copper alloy with superior Properties regarding eating wear, wear Resistance and corrosion resistance from 1.0 to 3.5 Wt% manganese, 0.3 to 1.5 wt% silicon, not less than 11.5 up to 25% by weight of zinc, 5 to 18% by weight of lead, of at least one component, selected from the group: 0.02 to 1.5% by weight of magnesium and 0.1 to 1.5% by weight of tellurium and balance copper and melting conditional impurities, being the lead in the structure consisting of only α-phase is uniformly distributed throughout the alloy.
• c) One for use as a material for a sliding or Sliding element suitable copper alloy with superior Properties regarding eating wear, wear Resistance and corrosion resistance from 1.0 to 3.5 Wt% manganese, 0.3 to 1.5 wt% silicon, not less than 11.5 to 25% by weight  Zinc, 5 to 18% by weight of lead, of at least one component, selected from the group: 0.5 to 3.0% by weight nickel and 0.3 up to 3.0 wt .-% aluminum, balance copper and smelting caused impurities, the lead in the structure consisting of only α-phase is uniformly distributed throughout the alloy.
• d) One for use as a material for a sliding or Sliding element suitable copper alloy with superior Properties regarding eating wear, wear Resistance and corrosion resistance from 1.0 to 3.5 Wt% manganese, 0.3 to 1.5 wt% silicon, not less than 11.5 to 25% by weight of zinc, 5 to 18% by weight of lead, at least one component, selected from the group: 0.02 to 1.5% by weight of magnesium and 0.1 to 1.5% by weight of tellurium, at least one component, selected from the group: 0.5 to 3.0% by weight nickel and 0.3 to 3.0 wt .-% aluminum, balance copper and melting conditional impurities, being the lead in the structure consisting of only α-phase is uniformly distributed throughout the alloy.

Below are the functions of the alloying elements and the reasons for limiting each element explained in more detail.

(1) Zinc (Zn): not less than 11.5 to 25% by weight

Zinc is an element that provides strength and wear resistance and corrosion resistance of the lubricating oil gives. The preferred content of this element depends on the zinc equivalents of the other elements, but should not less than 11.5% by weight since the above described effects at zinc levels below 11.5 % By weight are not significant. The amount of lead added  (Pb), which has traditionally been used to improve the stock added to a guzzling wear becomes. is undesirably restricted if that Microstructure has a mixed phase of α and β. Therefore, as Typically, the alloy according to the invention has a single-phase structure have the α-phase. So that a structure of only α-phase is ensured and thus the presence of the minimum amount, e.g. B. 5 wt .-% lead in the α-phase made possible light, the maximum content of zinc should be 25% by weight. be fixed.

(2) Manganese (Mn): 1.0 to 3.5% by weight

The manganese reacts with silicon (Si) to form the intermetallic compound Mn ₅ Si ₃ , which is superior in sliding properties, thereby contributing to the improvement of wear resistance and seizure resistance, while plastic flow of the matrix in the Fall of a metal-to-metal contact is prevented. In order to achieve a significant effect, the manganese should be contained in amounts of at least 1.0% by weight. On the other hand, a manganese content exceeding 3.5% by weight causes saturation of the effect and further undesirably causes embrittlement of the alloy.

(3) Silicon (Si): 0.3 to 1.5 wt%

As has already been stated, the silicon reacts with the manganese to form the intermetallic compound Mn ₅ Si ₃ , which contributes to an improvement in wear resistance and seizure resistance. The content of silicon be agrees according to the content of Mn ₅ Si ₃ , which is to be obtained. All the silicon is converted to the above-mentioned compound when the ratio of manganese content and silicon content in terms of weight ratio is 1: 0.3. Therefore, the silicon content should be at least 0.3 wt%. On the other hand, addition of silicon in excess of the upper limit of 1.5% by weight causes excessive crystallization of free silicon, resulting in embrittlement of the alloy.

(4) Lead (Pb): 5 to 18 wt%

Lead has self-lubricating properties and can by the Frictional heat can be easily melted, so that it is forming a thin film with a thickness of several The micron spreads on the sliding surface. hereby the resistance to a guzzling ver It is greatly improved, and it is furthermore a good machinability through cutting Production achieved. So that a thin lead film with a Thickness of several microns can be formed, it is necessary that the lead content is at least 5 wt .-%. On the other hand, an increase in the lead content causes a Reduction of the strength of the alloy, so that the maximum lead content is set at 18 wt .-%. The Lead content is therefore in the range between 5 and 18 wt .-%.

(5) Magnesium (Mg): 0.02 to 1.5 wt%

Magnesium is an element that is effective to lead uniformly disperse and continue to add the matrix solidify. These effects are not appreciable when the Magnesium content is below 0.02 wt .-%. on the other hand causes the addition of magnesium in an amount of more as 1.5 wt .-% too much crystallization of between metallic compounds of magnesium and lead, thereby the lead caused by the lubricating effect deteriorates  becomes. For these reasons, the magnesium content on the Range from 0.02% to 1.5% by weight.

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

The presence of a small amount of tellurium promotes the uniform dispersion of lead and improves the Toughness and resistance to a guzzling Wear and corrosion resistance of the alloy. However, these effects are not significant when the Tellurium content below 0.1 wt .-% is. on the other hand causes the addition of tellurium in amounts of more than 1.5 Wt .-% a significant saturation of the effect, while the Costs are increased uneconomically. Therefore the addition of tellurium is in the range of 0.1 to 1.5 Wt .-%.

(7) Nickel (Ni): 0.5 to 3.0 wt%

Nickel strengthens the matrix, giving the strength of the alloy tion is improved while at the same time the wear strength is increased. Nickel also increases the Rekristalli so that an enlargement of the crystal prevents grains during the plastic hot deformation However, these effects are not detectable when the nickel content is below 0.5% by weight. on the other hand affects the addition of nickel in excess of 3 Wt .-% significantly fatigue strength and the Impact resistance of the alloy. For these reasons, the Nickel content in the range of 0.5 to 3.0 wt .-% fixed.

(8) Aluminum (Al): 0.3 to 1.5 wt%

Aluminum also contributes to strengthening the matrix at. However, this effect is not significant when the Aluminum content is less than 0.3 wt .-%. on the other hand  causes an aluminum content of more than 1.5 wt .-% in uner desirably an embrittlement and coarsening of Kri stall grains. For these reasons, the aluminum content in the Range of 0.3 to 1.5 wt .-% fixed.

The following are examples of the invention Alloy with reference to the drawings closer be wrote. Show it:

Fig. 1 is a diagram showing, together with Table 4 to carry out the test on eating Ver wear,

FIG. 2 is a graph showing the results of the consumptive wear test; FIG.

FIG. 3 is a graph showing the results of the wear resistance test; and FIG

Fig. 4 is a diagram showing the results of the Cor rosionsbeständigkeitstests.

Examples Test Example 1 (Inventive alloy)

Alloys of compositions Nos. 1 to 9 according to Table 1 were prepared by a continuous casting process provides and by extrusion and deep drawing with bars deformed a diameter of 35 mm. The bars were in Properly processed to test specimens for the test on gnawing wear, the wear test and the To give corrosion test.

The conditions of the tests performed on these test pieces are shown in Tables 2 to 4 and FIG .

The results of the seizure and wear test are shown in Figs. 2 and 3, respectively. Representative values of the results of the corrosion test are shown in FIG .

Test Example 2 (Conventional Alloy)

Conventional alloys of Composition Nos. 10 to 13 shown in Table 1 were formed into ingots having a diameter of 35 mm by continuous casting, extrusion and deep drawing. The ingots thus obtained were subjected to the same tests as the test specimens of Test Example 1. The conditions of these tests are shown in Tables 2 to 4 and in Fig. 1, while the test results in Figs. 2 to 4 are shown.

Although the tests described with bars of alloys were made by continuous casting ago are naturally made the same Vor obtained by using alloys obtained by other casting methods, for example by stationary casting have been obtained.

Table 2

corrosion test test conditions oil Immersion in turbo-lubricating oil (equivalent to 15 W-40) test temperature 130 ° C test time 500 h, 1000 h

Table 4

Test for feeding wear

Table 5

Evaluation of the test results

(1) From the comparison of the results of the shown in Fig. 2 Darge presented test for seizure, it will be seen that the alloy according to the invention can be used up to the maximum load of 50 N / mm² without the risk of seizure. This is in contrast to the conventional free-cutting brass (# 10) and high-strength brass (# 12 and # 13).

(2) The alloy of the invention showed up in the test guzzling wear at a given number of revolutions in a real engine, there are no signs of a devouring wear. The engine contained a bearing from the respective alloy. The supply of lubricating oil was switched on and off according to Table 5. from that shows that the alloy according to the invention is used as a sliding or sliding material significantly improved behavior so that satisfactory results in Ver be expected as material for Gleitbüchsenlager can.

(3) As can be seen from Fig. 3, which shows the result of the wear test, the alloys according to the invention showed a lower degree of wear compared to conventional alloys, whereby a superior wear resistance is obtained. The wear test was performed after a wet process using a lubricating oil. Further, a quench hardened bearing made of the JIS S55C alloy was used as the opposite sliding member.

(4) Also, as shown in Fig. 4, showing the results of the corrosion test, the alloys of the present invention are superior in corrosion resistance to conventional alloys.

Thus, the copper alloy of the present invention is superior Properties in terms of resistance to guzzling wear, wear resistance, the Corrosion resistance and compatibility in Ver equal to conventional alloys. This own There are significant benefits, in particular when the alloy material of the invention as Ma terial used for a sliding or sliding element This is an improved behavior and improved Lifespan, as it is for example at a Sliding or sliding element of a turbocharger is the case.

Claims (4)

1. Copper-zinc alloy with better wear and corrosion resistance for use with sliding and sliding elements, characterized in that it consists of 1.0 to 3.5 wt .-% manganese, 0.3 to 1.5 wt. % Silicon, not less than 11.5 to 25 wt% zinc, 5 to 18 wt% lead, and copper remainder with impurities caused by melting, the lead being uniform in the α phase phase of the alloy is distributed. 2. Copper alloy according to claim 1, characterized that they have at least one component, selected from the group: 0.02 to 1.5% by weight of magnesium and 0.1 to 1.5% by weight of tellurium. 3. Copper alloy according to claim 1, characterized characterized in that they at least one component selected from the group: 0.5 to 3.0% by weight Nickel and 0.3 to 1.5 wt .-% aluminum. 4. Copper alloy according to claim 1, characterized that they have at least one component, selected from the group: 0.02 to 1.5% by weight of magnesium and 0.1 to 1.5% by weight of tellurium, and at least one component, selected from the group: 0.5 to 3.0 wt .-% nickel and 0.3 to 1.5 wt .-% aluminum.