DE102006060474A1 - bearings - Google Patents

Abstract

The present invention relates to a sliding bearing (10) comprising a carrier layer (12) made of a metallic material, a copper - based bearing metal layer (14) applied to the carrier layer (12), a diffusion barrier layer (16) applied to the bearing metal layer (14) and one on the Diffusion barrier layer (16) applied sliding layer (18) based on tin. According to the invention, it is provided that the diffusion barrier layer (16) consists of pure iron.

Description

The The present invention relates to a sliding bearing with a carrier layer made of a metallic material, one on the carrier layer applied copper-based bearing metal layer, one on the Lagermetallschicht applied diffusion barrier layer and a On the diffusion barrier layer applied on the Base of tin.

bearings in the form of lead-free laminates are used worldwide for new engines, especially for Transport and heavy duty vehicles needed, as more and more vehicles various types based on common vehicle platforms getting produced.

Known in the prior art is a sliding bearing made of a layered composite material which comprises a steel support layer, a lead-free bearing metal layer, an intermediate layer or diffusion barrier layer and a tin-based lead-free sliding layer. Such a plain bearing comes quite close to the known lead-containing plain bearings and represents an attempt to obtain the essential functional properties of these plain bearings, for example. Their good conformability and embedding ability, based on the soft, tin-based sliding layer, combined with a comparatively good load capacity and the good runflat in the event of complete wear of the sliding layer, which are based on the bearing metal layer. Such a sliding bearing is, for example, in the German patent application DE 103 37 030 A1 described.

In connection with such sliding bearings, however, it is a problem to limit the diffusion of tin from the sliding layer in the bearing layer, otherwise the brittle layer becomes brittle and the load capacity of the sliding bearing is significantly reduced. The German patent application DE 103 37 030 A1 proposes for this purpose that a diffusion barrier layer between the sliding layer and the bearing metal layer should be provided, which consist of pure nickel and should be about 4 to 6 microns thick.

These measure has to be improved proved because the nickel diffusion barrier layer must be comparatively thick. When tin from the sliding layer in the diffusion barrier layer migrates, there forms a tin and nickel existing diffusion layer. Now if the diffusion barrier layer made of pure nickel too thin is completely converted to a tin / nickel layer. The Tin in this new diffusion layer continues to migrate in the bearing metal layer. If, as usual, a bearing metal layer is used on the basis of copper, the tin forms with the Copper is a new, consisting of tin and copper diffusion layer. However, this diffusion layer is brittle, causing it to flake off inclines.

The Object of the present invention is therefore a slide bearing of the above type such that a better Control the diffusion of tin from the tin-based overlay in the bearing metal layer is possible.

The solution consists in a plain bearing with the features of the claim 1. According to the invention, it is provided that the diffusion barrier layer consists of pure iron.

It has surprisingly found that a pure iron diffusion barrier layer the migration or diffusion of tin from the sliding layer into the Warehouse metal layer effectively prevented. Diffusion-related reactions Do not even occur after long engine operating times. The diffusion barrier layer according to the invention Pure iron can also be easily applied to the bearing metal layer be applied, for example. By means of known galvanic methods.

advantageous Further developments emerge from the subclaims. Because of the Diffusion barrier layer according to the invention exerted Particularly effective diffusion barrier is sufficient if the diffusion barrier layer at the most 4 μm thick is. Preferred embodiments see a thickness of the diffusion barrier layer of at most 3 microns, especially preferably of at most 2 μm before. In order to Material costs are saved and the coating times shortened Diffusion barrier layer of the sliding bearing according to the invention shows its good Barrier effect independently of whether the overlay on a combination of tin and one or more several elements selected from the group: silver, copper, nickel, cobalt, zinc, gold, indium, Bismuth, lead, or whether the sliding layer contains pure tin. As well are advantageous tin alloys with nickel and / or zinc and or Cobalt and / or gold and / or bismuth and / or lead as a sliding layer can be used, wherein the tin content is at least 60 wt.%.

The Slip layer may differ from those known in the art Slide bearings with galvanically applied sliding layers also melt metallurgical be applied to the diffusion barrier layer. Can not do that only costs saved and particularly fine structures are achieved, but it open also new material compositions for the sliding layer. It can, for example. Alloy compositions used with galvanic Process are not representable, such as tin alloys with particular high silver or copper content or tin-nickel alloys.

The Bearing metal layer is a copper-based bearing metal layer, in a preferred embodiment has a copper content of at least 85 wt .-%. As another Alloy materials can For example, tin and / or nickel and / or bismuth be included.

Between the diffusion barrier layer 16 and the sliding layer 18 can be an intermediate layer 16b be provided, for example, a galvanically applied tin or silver or nickel layer or an alloy thereof. This serves as a corrosion protection layer and additionally increases the emergency running properties, in the event that after extended operation, the sliding layer is worn in the region of high load.

In the case where the sliding layer is applied by fusion metallurgy, the intermediate layer serves 16b the adhesion promoter and is then preferably made of tin.

An embodiment of the present invention will be described below with reference to the accompanying drawings. The 1 shows a schematic, not to scale true representation of a cross section through an embodiment of a sliding bearing according to the invention 10 , This slide bearing 10 has a carrier layer 12 , preferably of steel, on which a bearing metal layer 14 is based on copper, for example, consists of a copper-tin alloy or a copper-tin-nickel alloy or a copper-tin-bismuth alloy or a copper-tin-bismuth-nickel alloy, wherein the Each copper content is at least 85 wt .-%. On the bearing metal layer 14 is a diffusion barrier layer 16 and on this a sliding layer 18 applied on the basis of tin. The sliding layer 18 contains tin and one or more elements selected from the group: silver, copper, nickel, indium, cobalt, zinc, gold, bismuth, lead. The sliding layer 18 can also consist of pure tin. In the embodiment, a eutectic tin-silver alloy having a tin content of 96% and a melting point of 221 ° C was used. Also conceivable would be a eutectic tin-silver-copper alloy with a melting point of 217 ° C. In order to facilitate the molten deposition of the tin layer, it may be advantageous to add bismuth to the alloy. This further reduces the melting point.

The molten tin or the molten tin-based alloy is applied to the diffusion barrier layer 16 or on an extra layer 16b , as in 2 shown, applied. The removal of the excess tin or the excess alloy from the surface is carried out by a known brushing process or by centrifuging the excess still molten tin or the alloy. For this purpose, the sliding bearing is subjected to a corresponding centrifugal movement.

The pure iron diffusion barrier layer 16 is galvanic on the bearing metal layer 14 applied and effectively prevents the migration or diffusion of tin in the bearing metal layer 14 , The diffusion barrier layer 16 can therefore have a layer thickness of at most 4 microns, preferably at most 3 microns, more preferably at most 2 microns.

Embodiment 1 (cf. 1 ):

• Support layer made of steel ( 12 );
• Bearing metal layer of a copper alloy 200 μm layer thickness ( 14 );
• Diffusion barrier layer of pure iron, 2 μm layer thickness ( 16 );
• Galvanically applied sliding layer made of a tin-silver alloy with 8% by weight silver, 12 μm layer thickness ( 18 ).

Exemplary embodiment 2 (compare 2 ):

• Support layer made of steel ( 12 );
• Bearing metal layer of a copper alloy 190 μm layer thickness ( 14 );
• Diffusion barrier layer of pure iron, 2 μm layer thickness ( 16 );
• Additional layer of galvanized tin, 2 μm layer thickness ( 16b );
• Melt metallurgically applied sliding layer of a tin-nickel alloy with 3% by weight nickel, 20 μm layer thickness ( 18 ).

Claims (9)

Bearings ( 10 ) with a carrier layer ( 12 ) of a metallic material, one on the carrier layer ( 12 ) applied copper-based bearing metal layer ( 14 ), one on the bearing metal layer ( 14 ) applied diffusion barrier layer ( 16 ) and one on the diffusion barrier layer ( 16 ) applied sliding layer ( 18 ) based on tin, characterized in that the diffusion barrier layer ( 16 ) consists of pure iron. Plain bearing according to claim 1, characterized in that the diffusion barrier layer has a thickness of at most 4 μm, preferably at most 3 μm, especially preferably at most 2 microns. Sliding bearing according to one of claims 1 or 2, characterized in that between the diffusion barrier layer ( 16 ) and the sliding layer ( 18 ) an intermediate layer ( 16b ) to improve the emergency running properties and corrosion protection see is. Plain bearing according to claim 3, characterized in that the intermediate layer ( 16b ) is a preferably electroplated tin or silver or nickel layer. Sliding bearing according to one of the preceding claims, characterized in that the sliding layer ( 18 ) based on tin of either pure tin or tin and one or more elements selected from the group: silver, copper, nickel, indium, cobalt, zinc, gold, bismuth, lead. Sliding bearing according to one of the preceding claims, characterized in that the sliding layer ( 18 ) of a tin alloy with nickel and / or zinc and / or cobalt and / or gold and / or bismuth and / or lead can be used as a sliding layer, wherein the tin content is at least 60% by weight. Sliding bearing according to one of the preceding claims, characterized in that the sliding layer ( 18 ) based on tin metallurgically on the diffusion barrier layer ( 16 ) or on the intermediate layer ( 16b ) is applied. Sliding bearing according to one of the preceding claims, characterized in that the bearing metal layer ( 14 ) has a copper content of at least 85% by weight. Slide bearing according to claim 8, characterized in that the bearing metal layer ( 14 ) further contains tin and / or nickel and / or bismuth.