WO2015113092A1

WO2015113092A1 - Sliding bearing

Info

Publication number: WO2015113092A1
Application number: PCT/AT2015/050026
Authority: WO
Inventors: Lukas HÄDICKE
Original assignee: Miba Gleitlager Gmbh
Priority date: 2014-01-31
Filing date: 2015-01-28
Publication date: 2015-08-06
Also published as: AT515107B1; AT515107A4

Abstract

The invention relates to a sliding bearing (1) comprising a supporting layer (2) and an antifriction layer (3) which is arranged on the supporting layer (2) and is connected to same, the antifriction layer (3) consisting of a tin based alloy containing magnesium. The magnesium proportion is selected from a range with a lower limit of 0.5% by weight and an upper limit of 9% by weight, the remainder being tin and production-related impurities.

Description

bearings

The invention relates to a slide bearing with a support layer and a running layer, which is arranged on the support layer and connected thereto, wherein the running layer consists of a tin-based alloy. Furthermore, the invention relates to a method for producing a slide bearing comprising the steps:

providing a support metal layer,

optionally applying a bonding layer to the supporting metal layer,

- Pour a barrel layer of a tin-based alloy by centrifugal casting. The use of white metals in plain bearing technology has been known for a long time. Due to the demand of low-emission (two-stroke) engines, especially marine diesel engines, and the associated higher ignition pressures, plain bearings are exposed to increasing load. Such motors usually have powers in the range between 4000 kW and 90000 kW. In this application of white metal plain bearings, the goal is to have a particularly soft and forgiving overlay, which also withstands the increased ignition pressures.

White metals are often processed by centrifugal casting, whereby the composition of the alloy is limited due to the centrifugal force during the Aufgießens. The currently used white metal alloys are characterized by the use of solid solution hardening and hardening by heterogeneous precipitation. For solid solution hardening usually antimony, bismuth or cadmium are added. For hardening copper, nickel, cobalt, aluminum or zinc are used. However, the risk of heterogeneous excretion is the forced gravity segregation, which is already difficult to control, and the reduction in ductility due to the increased proportion of brittle phases. Hardening by compression or fine grain hardening, for example by alloying tellurium or arsenic, are not or only briefly effective because of the relatively high temperatures used for white metals. However, there are also white metal alloys known in which both the effect of solid solution hardening and the Kornf tion is exploited. For example, from the WO

2012/028136 A2 is a plain bearing alloy known with 6 wt .-% -18 wt .-% Sb, 3 wt .-% - 10 wt .-% Cu, 0.5 wt .-% - 3.5 wt .-% Bi, 0 wt .-% - 2.0 wt .-% Zn, 0 wt .-% - 0.5 wt .-% Mg, 0 wt .-% - 0.5 wt .-% Li, 0 wt. -% - 0.5 wt .-% Au, 0 wt .-% - 1 wt .-% Cr, 0 wt .-% -1 wt .-% Ag, 0.01 wt .-% - 0.04 wt .-% of a Kornf tion smit- tels formed by one or more elements from the group Te, Se, Ce, Ni, and the rest Sn and the unavoidable impurities.

As can be seen from all of this, there are many different approaches in the prior art to improve the strength of white metal based sliding bearing alloys.

The present invention is also based on the object of specifying a tin-based alloy, in particular for centrifugal casting, which has a relatively high strength and is lead-free.

This object is achieved in the slide bearing mentioned above and the aforementioned method for producing a plain bearing in that the tin-based alloy contains magnesium, wherein the magnesium content is selected from a range with a lower limit of 0.5 wt .-% and a upper limit of 9 wt .-%.

The advantage here is that the magnesium with tin forms the intermetallic phase Mg2Sn, which increases the strength of the tin matrix. Due to the proportions of magnesium, in contrast to the usual precipitation hardening by intermetallic phases but worked in the eutectic composition, whereby the microstructure with respect to Mg2Sn is very fine-grained. It is thus achieved on the one hand that even small amounts of magnesium are sufficient for an increase in strength of the tin-based alloy, so that a running layer can be obtained, which not only good-natured Fressneigungen and a relatively high hardness, but this running layer due to the high tin content also compared to PRIOR ART White metal working layers exhibit at most slight changes in ductility compared to heterogeneous precipitation hardening. Due to the high fatigue strength of the overlay, the damage progress can be bender load the running layer can be operated for a longer period of time until the occurrence of the damage or it can be exposed to a higher load for a constant period of time until the occurrence of damage. As a result of the fine-grained eutectic precipitations, a micro-composite within the overlay is achieved, which also has a positive effect on the mechanical properties of the overlay. A further advantage is the fact that this eutectic composition has at least approximately no propensity to segregation, so that the production of the overlay can be significantly simplified by centrifugal casting, or it can thus be easier to assemble the overlay itself, since no further additives for the Reduction of segregation is necessary.

According to a variant embodiment of the sliding bearing or of the method, it is provided that the tin-base alloy additionally contains zinc, the zinc portion being selected from a range with a lower limit of 0.5% by weight and an upper limit of 6.5% by weight. %. Due to this amount of zinc, the binary eutectic system is extended to a ternary, so that the preceding effects also apply to this variant. However, this ternary eutectic consumes only a portion of the magnesium, resulting in the excretion of coarser Mg ₂ Sn grains. It can thus be achieved a further increase in the hardness of the overlay with negligible drop in ductility. In addition, the segregation of these coarser Mg ₂ Sn grains can be reversed compared to known from the prior art Weißmetalllaufschichten so that during the production of the overlay by centrifugal casting simultaneously a hardness gradient can be formed with increasing hardness in the direction of the tread , Due to the hardness gradient, a better adaptation to the hard supporting metal layer can be achieved, in that the bonding zone to the supporting metal layer does not have too high a strength and thus an embrittlement of the binding zone can be better avoided. As a result, the bond strength of the composite material can be improved. In addition, zinc causes an improvement in solid solution strengthening and layer adaptability. According to another embodiment variant of the sliding bearing or of the method, it can be provided that the tin-base alloy additionally contains bismuth, the bismuth portion being selected from a range with a lower limit of 0.5% by weight and an upper one Limit of 4.5% by weight. In turn, a ternary eutectic excretion of Mg ₂ (Sn, Bi) is achieved, which increases the hardness of the tin matrix.

It can further be provided that the tin-based alloy is arranged directly on the support layer. It can thus be simplified, the construction of the plain bearing, whereby their production costs can be reduced. In addition, however, the process technology can be simplified.

On the other hand, it can also be provided that a bonding layer is arranged between the support layer and the tin-base alloy in order to achieve an improved bond strength between the support metal layer and the overlay.

Preferably, the bonding layer is formed by tin, copper, zinc or the alloys of these elements, since at the same time a diffusion barrier for diffusing from the running layer in the supporting metal layer metals can be achieved, which in turn embrittlement of the bonding zone by formation of intermetallic brittle with the / the Metal (s) of the support metal layer can be prevented.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Each shows in a simplified, schematic representation:

Fig. 1 is a plain bearing in an oblique view.

By way of introduction, it should be noted that the location information chosen in the description, such as the top, bottom, side, etc. are related to the immediately described and illustrated figure and these position information in a change in position mutatis mutandis to transfer to the new location.

Fig. 1 shows a plain bearing 1 in an oblique view. The plain bearing 1 comprises or consists of a support layer 2 and a running layer 3 arranged thereon and connected thereto. The non-closed sliding bearing 1 may in addition to the half-shell design with an angular range of overlap of at least approximately 180 ⁰ a deviating angular range overlap comprise, for example, at least approximately 120 ⁰ or at least approximately 90 ° so that therefore the sliding bearing 1 as a third shell or quarter cup may be formed, which are combined with corresponding further bearing shells in a bearing receptacle, wherein the sliding bearing 1 is preferably installed according to the invention in the higher loaded area of the bearing receptacle. But there are also other embodiments of the sliding bearing 1 possible, for example, a design as a bearing bush, as indicated by dashed lines in Fig. 1.

The support layer 2 is usually made of a hard material. As materials for the support layer 2, also called support shell, bronzes, brass, etc. can be used. In the preferred embodiment of the invention, the support layer 2 consists of a steel.

The running layer 3 is formed in the embodiment of FIG. 1 as a sliding layer, which is in direct contact with the component to be stored, for example, a shaft.

It is within the scope of the invention but in addition to the two-layer design also the ability to construct the plain bearing 1 of more than two layers. In this case, the running layer 3 is a bearing metal layer on which subsequently the sliding layer, e.g. made of a lubricating varnish, is applied. There is the possibility that at least one intermediate layer is arranged between this bearing metal layer and the sliding layer, for example a diffusion barrier layer and / or a bonding layer.

Such constructive structures of multilayer plain bearings are known in principle from the prior art, so that reference is made in this regard to the relevant prior art.

The running layer 3 is made of tin-based alloy. In the simplest embodiment of the sliding bearing 1, the tin-based alloy is a binary alloy of tin and magnesium. Of the The proportion of magnesium in the tin-base alloy is selected from a range having a lower limit of 0.5 wt% and an upper limit of 9 wt%. The remainder to 100 wt .-% forms tin with the usual melting impurities. The tin-based alloy thus has a composition in the range of the eutectic composition or the eutectic composition.

With this composition Mg ₂ Sn grains are precipitated during solidification, which are finely distributed in the matrix. The advantage here is that the solidification is very rapid, so no or no large temperature interval of solidification is passed through, so that so the tin-based alloy has no time to seigern.

With a magnesium content of less than 0.5 wt .-%, the proportion of Mg ₂ Sn grains in the tin matrix is too low, so that the desired increase in strength is too low, and thus the fatigue strength is not sufficient for the currently required loads of the slide 1.

With a magnesium content of more than 9% by weight, on the other hand, the proportion of the tin matrix in the alloy is excessively reduced by the higher proportion of Mg ₂ Sn grains, which also reduces too much the ductility of the overlay 3 and thus the adaptability of the Running layer 3 to the respective sliding partner or generally the tribological properties of the overlay 3 are degraded.

Preferably, the proportion of magnesium in the tin-based alloy is selected from a range having a lower limit of 0.5 wt% and an upper limit of 6.5 wt%.

More preferably, the proportion of magnesium in the tin-based alloy is selected from a range having a lower limit of 0.5 wt% and an upper limit of 5 wt%. In the eutectic composition, the overlay 3 of this embodiment consists of 1.9% by weight of magnesium and 98.11% by weight of tin. Instead of a binary tin-based alloy, however, the overlay layer 3 may also consist of a ternary tin-based alloy.

This ternary tin-based alloy can be made in a first embodiment of magnesium, zinc and tin with the melt-related impurities.

The proportion of magnesium may be selected from the ranges mentioned above.

The amount of zinc may be selected from a range having a lower limit of 0.5 wt% and an upper limit of 6.5 wt%.

The remainder to 100% by weight forms the tin (with the impurities due to melting). With a proportion of zinc of less than 0.5 wt .-%, no or no sufficient effect can be seen.

With a proportion of zinc of more than 6.5 wt .-%, however, there is too strong corrosion tendency of the alloy.

Preferably, the proportion of zinc is selected from a range having a lower limit of 0.5 wt% and an upper limit of 6 wt%.

More preferably, the amount of zinc is selected from a range having a lower limit of 0.5 wt% and an upper limit of 5.5 wt%.

In particular, the running layer 3 may be made of a tin-based alloy having a zinc content selected from a range having a lower limit of 3.5% by weight and an upper limit of 4.5% by weight and a magnesium content selected from a range having a lower content. lower limit of 1 wt .-% and an upper limit of 4.5 wt .-% consist. In the eutectic composition, the overlay layer 3 consists of 1.5% by weight of magnesium, 7.5% by weight of zinc, the remainder to 100% by weight forming the tin (with the impurities caused by melting). The ternary tin-based alloy may consist in a further embodiment of magnesium, bismuth and tin with the impurities caused by melting.

The proportion of magnesium may be selected from the above ranges for the binary tin-magnesium alloys.

The proportion of bismuth may be selected from a range having a lower limit of 0.5 wt% and an upper limit of 4.5 wt%.

The remainder to 100% by weight forms the tin (with the contaminations due to melting).

With a bismuth content of less than 0.5% by weight, the effect of the bismuth additive is too low. In the case of a bismuth content of more than 4.5% by weight, on the other hand, the melting point of the alloy is lowered too much.

Preferably, the proportion of bismuth is selected from a range having a lower limit of 0.5 wt% and an upper limit of 4 wt%.

The proportion of bismuth is particularly preferably selected from a range with a lower limit of 0.5% by weight and an upper limit of 3.5% by weight.

Specifically, the overlay layer 3 may be made of a tin-base alloy having a bismuth portion selected from a range having a lower limit of 0.7 wt% and an upper limit of 3 wt% and a magnesium content selected from a lower limit of 1 range Wt .-% and an upper limit of 4.5 wt .-% exist. In the eutectic composition, the overlay layer 3 consists of 2% by weight of magnesium, 2% by weight of bismuth, the remainder to 100% by weight forming the tin (with the impurities caused by the melt). In addition to the abovementioned alloy constituents, however, the tin-base alloy of the overlay 3 may also have further constituents, in particular for grain refinement and / or refinement of the alloy. These may be selected from a group comprising or consisting of palladium, gold, strontium, manganese, platinum, iron, ruthenium, cobalt, sodium, copper, phosphorus, barium, chromium, nickel, zirconium, silicon, arsenic, cadmium, aluminum ,

The total amount of these additional constituents is between 0 wt .-% and 5 wt .-%, in particular between 0.1 wt .-% and 5 wt .-%, with the proviso that the sum of the elements of palladium, gold, manganese, Platinum, iron, ruthenium, cobalt, copper, chromium, nickel, zirconium between 0 wt .-% and 4 wt .-%, in particular between 0.1 wt .-% and 4 wt .-%, is.

These elements can be used to control eutectic solidification and microstructure or morphology.

The overlay 3 is therefore lead-free.

The production of the sliding bearing 1 is preferably carried out by Schleudergus s. In this case, the tin-base alloy is spin-coated onto a cleaned metal strip, which forms the support layer 2 in the sliding bearing 1, to form the overlay 3. After solidification of the overlay layer 3, a further mechanical processing of the overlay layer 3, for example by fine boring, take place. This basic procedure is known from the prior art, so that reference is made to the relevant prior art. The running layer 3 can be applied directly to the support layer 2. But there is also the possibility that between the support layer 2 and the running layer 3, a bonding layer 4 is arranged, as indicated by dashed lines in Fig. 1. This bonding layer 4 may be formed according to the prior art for bonding layers. The support layer 2 may have a layer thickness between 5 mm and 35 mm. The running layer 3 may have a layer thickness between 0.5 mm and 5 mm.

The bonding layer 4 may have a layer thickness between 1 μιη and 1 mm.

In the context of the invention, the test patterns specified in Table 1 were produced from a steel half-shell as support layer 2 and the running layer 3 from the tin-based alloy by means of centrifugal casting using the parameters mentioned above. All information on the composition is to be understood in% by weight.

Table 1: Compositions of tin-base alloys of the overlay layer 3

No Mg Zn Bi Sn Brinell hardness

(HB) 2.5 / 15.625)

1 0.08 5.1 0 94.82 26.3

2 0.1 0 4.1 95.8 21.2

3 0.13 0 4.8 95.07 23.2

4 0.2 0 4.3 95.5 19

5 0.24 0 6.7 93.06 18.4

6 0.27 0 16.7 83.03 23.4

7 0.37 5 0 94.63 23.2

8 0.37 0 3.2 96.43 28.3

9 0.42 3.2 0 96.38 23.2

10 0.44 8.5 0 91.06 24.1

11 0.44 0 3.1 96.46 23.4

12 0.49 3.7 0 95.81 27.4

13 0.55 4,6 0 94,85 25,5

14 0.74 7.6 0 91.66 24.5

15 0.83 0 4.5 94.67 28.6

16 0.95 0 1.8 97.25 18.7 17 1.2 6.1 0.92.7 30.8

18 1.36 3.3 0 95.34 31.4

19 1.38 3.5 0 95.12 31.6

20 1.5 0 2.5 96 19.8

21 1.5 0 3.5 95 27.6

22 2 0 3 95 27.6

23 2 4,7 0 93,3 37,6

24 2.2 5.9 0 91.9 33.6

25 2.5 0 2.5 95 30

26 2.5 0 3.5 94 26.3

27 3.5 3.5 0 93 22.9

28 3.5 4.5 0 92 28.6

29 4 4 0 92 25.1

30 4.5 3.5 0 92 23.2

31 4.5 4.5 0 91 29.3

For comparison, a sliding bearing 1 was produced with a steel support layer 2 and a running layer 3 made of TEGOSTAR. The running layer 3 had a Brinell hardness of 27 HB 2.5 / 15.625 in this comparative example.

As can be seen from the results, the running layer 3 according to the invention has a hardness of at least 30 HB 2.5 / 15.625. The embodiments show possible embodiments of the sliding bearing. 1

For the sake of order, it should finally be pointed out that, for a better understanding of the structure of the sliding laser 1, this or its components have been shown partially unevenly and / or enlarged and / or reduced in size. Reference signs slide bearing

backing

Run layer

bonding layer

Claims

Patent claims

1. plain bearing (1) with a support layer (2) and a running layer (3) on the

Support layer (2) is arranged and connected thereto, wherein the running layer (3) consists of a tin-based alloy, characterized in that the tin-based alloy contains magnesium, wherein the magnesium content is selected from a range with a lower limit of 0.5 wt. % and an upper limit of 9 wt .-% and the remainder tin with the production-related impurities forms.

Sliding bearing (1) according to claim 1, characterized in that a part of the tin fraction is replaced by zinc, the zinc fraction being selected from a range with a lower limit of 0.5% by weight and an upper limit of 6, 5% by weight.

3. sliding bearing (1) according to claim 1 or 2, characterized in that a part of the tin content is replaced by bismuth, wherein the bismuth portion is selected from a range having a lower limit of 0.5 wt .-% and an upper limit of 4.5% by weight.

4. plain bearing (1) according to one of claims 1 to 3, characterized in that the tin-based alloy is arranged directly on the support layer (2).

5. plain bearing (1) according to one of claims 1 to 3, characterized in that between the support layer (2) and the Zinnbasislegierung a bonding layer (4) is arranged.

6. plain bearing (1) according to claim 5, characterized in that the binding layer

(4) is formed by tin or copper or zinc or an alloy of these elements.

7. A method for producing a sliding bearing (1) comprising the steps:

providing a support layer (2),

optionally applying a bonding layer (4) to the support layer (2),

- Casting a running layer (3) of a tin-based alloy by centrifugal casting, characterized in that a tin-based alloy is poured, the magnesium is added in a proportion which is selected from a range with a lower limit of 0.5% by weight and an upper limit of 9% by weight, with the remainder forming tin with the production-related impurities.

8. The method according to claim 7, characterized in that a part of the Zinnan part is replaced by zinc, wherein zinc is added in a proportion which is selected from a range with a lower limit of 0.5 wt .-% and a upper limit of 6.5% by weight.

9. The method according to claim 7 or 8, characterized in that a part of the tin content is replaced by bismuth, wherein bismuth is added in a proportion selected from a range with a lower limit of 0.5 wt .-% and an upper limit of 4.5% by weight.