DE102007049042A1 - Slide bearing with sliding layer and inlet layer - Google Patents

Abstract

Sliding bearing comprising a bearing back (5), a running layer (4), a diffusion barrier layer (3), a sliding layer (2) and a running-in layer (1), characterized in that the sliding layer (4) is formed by an Al / Bi alloy which has a Bi content of 1.5-21.5 wt% Bi, and the run-in layer is formed of Bi or a Bi alloy having a Bi content above 90 wt%.

Description

The Invention relates to plain bearings, in particular for connecting rods, Main bearings, camshaft bearings, exhaust gas turbocharger bearings or bearing blocks of internal combustion engines, comprising a bearing back, a running layer, a diffusion barrier layer, a sliding layer and an inlet layer, wherein the sliding layer by an Al / Bi alloy and the inlet layer are formed by a Bi alloy and their production process, wherein at least the diffusion barrier layer, the Bi and the Al / Bi layers be sputtered.

in the Engine housing and connecting rods of internal combustion engines work at different points rotating shafts, such as crankshaft, Camshaft, rocker arm shaft or balance shaft. Support sliding bearing these off. The demands on the plain bearings are rising steadily, in particular by increasing the ignition pressures of up to 200 bar. In addition, the specific engine power increased, the sizes reduced and the space continuously reduced for the bearings. At the same time the oil change intervals for new engine designs successively extended.

conventional Two- and three-layer bearings, their running layers applied galvanically are already reaching their limits, as these are Bearing insufficient fatigue strength and wear resistance, especially in mixed friction range. Likewise at higher temperatures improved corrosion resistance to be guaranteed.

recent Developments go to three-component bearings where run coating is not is applied by electroplating, but instead by sputtering. They consist of the steel support shell, a running layer, a barrier layer and the sliding layer.

From the DE 10 2004 055 228 A1 a bearing shell of a connecting rod is known, wherein the bearing shell consists of several thermally sprayed layers. The uppermost material layer or sliding layer or the entire bearing shell is essentially formed from an aluminum / bismuth alloy. The manufacturing method comprises the steps of mechanically roughening the surface of the connecting rod in the region of the bearing, coating the surface by means of thermal spraying with a bearing metal or a bearing material to form a bearing layer and coating the bearing layer by means of thermal spraying with an Al / Bi alloy to form a sliding layer.

From the DE 10 2004 055 228 A1 a bearing shell of a connecting rod is known, wherein the bearing shell of a plurality of thermally sprayed layers and the uppermost layer of material of the bearing shell is formed essentially of an aluminum / bismuth alloy or the entire bearing shell essentially formed from a thermally sprayed layer of aluminum / bismuth alloy is.

From the DE 10 2005 050 374 A1 are sliding layers, in particular for bearings in crankshaft or connecting rod bearings known, which consists of a gas phase coating of aluminum alloy with the essential alloying components Bi and / or Sn, Cu and Si, the Si predominantly as globular coarsely crystalline precipitates in a homogeneous and microcrystalline matrix made of aluminum alloy.

The WO 2006120025 A1 describes a sliding bearing composite material with a carrier layer made of a copper alloy and with a sliding layer applied to the carrier layer. The copper alloy support layer may comprise 4-11% by weight of nickel, 3 to 8% by weight of tin and at most 0.1% by weight of lead. The sliding layer may be a galvanic layer, a sputtering layer or a plastic layer. On this, inlet layers can be arranged.

It has been shown that the known heavy-duty sliding layers In the field of mixed friction still need to be improved. This is especially due to an unfavorable run-in behavior attributed to the moving parts. While the first commissioning in the newly manufactured motor vehicle engines may be due to uneven lubrication Tribological stresses occur, some of them too sustainable Damage to the sliding layers can lead.

It is therefore an object of the invention, heavy-duty sliding layers on To provide bearings in engines that in mixed friction, in particular at first startup or when running in, an improved Have behavior and to identify suitable methods such To produce bearings.

The The object is achieved by a sliding bearing comprising a bearing back, a running layer, a diffusion barrier layer, a sliding layer and an inlet layer, wherein the sliding layer is formed by an Al / Bi alloy, which has a Bi content of 1.5-21.5 wt .-% Bi and the run-in layer of Bi or a Bi alloy with a Bi content above 90 wt .-% is formed, with the features of the claim 1.

Another solution according to the invention is a method in which both the diffusion barrier layer ( 3 ) as well as the sliding layer ( 2 ) when also the enema layer ( 1 ) by sputtering on the back of the bearing ( 5 ) or the running layer ( 4 ), which method has the features of claim 8.

Especially advantageous embodiments are the subject of the dependent claims.

The The invention will be described with the aid of a schematic illustration explained in more detail.

there shows:

1 a slide bearing with a bearing back ( 5 ), a layer of bearing metal ( 4 ), a thin adhesion promoter layer or diffusion barrier layer ( 3 ), a sliding layer ( 2 ) and an enema layer ( 1 ).

From special importance for the invention is thus, the combined Use of Bi in overlay and run-in layer. While the Bi in the sliding layer as an alloying component of an Al / Bi alloy with a Bi content of 1.5-21.5 wt .-% occurs is the Enema layer essentially a bi-layer whose bi-content above 90% by weight.

The Good tribological properties of the sliding layer arise from a combination of metal matrix of an Al alloy with a disperse phase of Bi or a refractory Bi alloy. The Bi forms because of its low solubility Precipitates in the main metal component Al. These monotectic Bi / Al alloys belong to the class of immiscible alloys, the means in the molten state there is one Range of compositions by the involved components are immiscible. Will the bearing layer of the invention formed or deposited at elevated temperatures and cooled down very quickly, so it forms a very fine structure with a defined disperse phase of Bi or Bi alloy out.

The softer bi-phase contributes significantly to lubricating Effect of the alloy, while the Al, the sliding layer protects against tribological destruction, resp. counteracts the removal of the sliding layer. In rising or however, too high an amount of Bi, the slip layer is increasingly losing Stability and is the requirements of the high loads no longer up to it.

Surprised has been shown that the required Bi content in the overlay when using a run-in layer of Bi opposite noticeably lower the known Al / Bi alloys. The High tribological load in the run-in phase is virtually through the pure bi-inlet layer intercepted. After running in will the sliding surface essentially only through the Sliding layer formed, which now has a comparatively lower Bi content, or higher Al content has.

In Another preferred embodiment of the invention comprises the Al / Bi alloy the sliding layer has a Bi content of 2-10 wt .-% Bi and the Bi alloy of the inlet layer has a Bi content above 98% by weight.

Especially Preferably, the Al / Bi alloy of the sliding layer is at a Bi content from 3-7% by weight. The running-in layer is particularly preferred made of pure Bi.

In Al / Bi alloy can be used as further alloy components in particular Cu or Sn contained. Preferred is an Al / Bi alloy with 0.1 to 5 wt .-% Cu.

In further preferred development of Al / Bi alloys included this is an Si content of 0.5 to 5 wt .-%.

at the formation of the disperse phase, it is important in which Particle size are the dispersoids of Bi. On the one hand, the dispersoids have a certain size have to exert their mechanical effect in the sliding systems on the other hand, they must not be too big so that one can arise in homogeneous material. The cheap Particle size of the dispersoids is in the range from about 50 nm to 1 μm. Preferred is the essential Proportion of Bi or Bi alloy so finely distributed, that light microscopic no primary phases are recognizable and they behave X-ray amorphous, that is not by X-ray diffraction examination are more detectable. It is preferable that the sliding layer a gas phase coating, in particular a sputtering layer.

The Layer thicknesses of the sliding layer is typically in the range of few μm up to several 100 μm. Especially preferred a layer thickness in the range of 5 to 20 microns is set.

in the In comparison, the running layer preferably has a thickness in the range from 0.5 to 10 .mu.m, in particular 1-6 microns on.

A particularly suitable coordinated stratification is through a sliding layer with a thickness of 6-15 microns and an inlet layer of 2-4 μm.

In a further preferred embodiment, the inlet layer is a PVD (physical vapor deposition) deposited or sputtered coating. It has surprisingly been found that for the Inlet layer a comparatively hard and well-adherent Bi-layer is particularly suitable. In contrast, soft inlet layers are rather unsuitable, especially for the high loads when entering. Sputtered Bi layers are distinguished from the alternatively available by electrodeposition layers by significantly higher material strengths and better adhesion to the underlying layers. This also applies to the usual PVD methods.

For highly loaded bearings, for example in the commercial vehicle sector, the sliding bearing is usually made of a bearing back ( 5 ) made of steel, or a bearing shell made of steel on the one running layer ( 4 ) of bearing metal, a primer layer or diffusion barrier layer ( 3 ), a sliding layer ( 2 ) and an enema layer ( 1 ) are arranged. It may also be appropriate, in particular for small motors or bearings, to dispense with the steel part or the bearing shell and the running layer ( 4 ) Apply directly to the base workpiece. Here is also spoken by bearing shellless camp. The bearing back ( 5 ) is thus formed either by an insertable into the bearing component steel shell or by the surface of the bearing component itself.

To the most suitable bearing metals are in particular Cu / Ni, Cu / Sn / Bi alloys or bronzes. With the bearing shellless Storage is preferably thermal sprayed coatings, for example, LDS layers.

Above the sliding layer is a diffusion barrier layer ( 3 ) or adhesion promoter layer. This is preferably formed by Ni or a Ni alloy. Their thickness is typically about the thickness of the inlet layer.

Possibly can on the inlet layer a from corrosion and damage protective coating may be arranged. It has been shown that the very thin sputter layers are easy to handle to be damaged. By storage or improper Handling, the metallic layers can also corrode. A further embodiment therefore provides that the Running-in layer with a paint or a plastic coating is provided.

The Plain bearings are preferred for connecting rods, main bearings, camshaft bearings, Turbocharger bearings or storage chairs used by internal combustion engines.

In further embodiment, the respective bearings depending on Stress locally be differently structured. It can Bearing pairs are formed from the invention Slide bearing and a conventional three-ball bearing. Just at the more heavily loaded site then the inventive Sliding bearing used, while compared to the softer Bearings, especially a three-ball bearing is used. For example is at the connecting rod bearing the sliding bearing according to the invention mounted in the direction of the rod, the three-point bearing towards the bearing cap. At the Main bearing is the sliding bearing according to the invention in the bearing cap, the three-part bearing is inserted in the direction of the engine block.

To the method particularly suitable according to the invention for the production of the layers belong the sputtering method, often also as a sputtering process referred to as well as PVD method.

An inventive method for producing the slide bearing provides that both the diffusion barrier layer ( 3 ) as well as the sliding layer ( 2 ) as well as the enema layer ( 1 ) by sputtering on the back of the bearing ( 5 ) or the running layer ( 4 ) are deposited.

As sputtering target corresponding Al / Bi alloys, Ni alloys or the Bi can be used. Preferably, however, a plurality of sputtering targets of different composition are used, for example for the overlay ( 2 ) of the bismuth-free Al alloy and of the Bi alloy, in particular of pure Bi. The mixing ratios can be adjusted to one another, inter alia, in a known manner by the size or area ratios of the different targets. The different targets can be used alternately, so that alternate during the deposition of atomic layers of Al alloy and Bi alloy. The thickness of the deposited atomic layers and thus the homogeneity of the layer can be set and controlled via the sputtering times of the different targets. The sputter layers are fine-grained, finely dispersed and adhere well to the substrate. Due to the small grain size, the layer thus produced has excellent hardness, high strength and best wear properties.

The Sputtering processes have the advantage that the formation of a melt phase the deposited components is essentially omitted and the deposited particles are quasi mixed at the atomic level. During the tribological use of plain bearings occurs then recrystallization.

With regard to the different material layers deposited after each other, sputtering is very well suited for designing comparatively flat material transitions. It is advantageous that the layers of material do not merge abruptly, but flow into one another. This will become Materialgradienten formed at least in the transition region between the individual material layers. This procedure leads to very good interlaminar layer adhesion, which is considerably higher, for example, compared to galvanic deposition, in particular the inlet layer of Bi.

Both the diffusion barrier layer ( 3 ) as well as the sliding layer ( 2 ) as well as the enema layer ( 1 ) are deposited in a single sputtering system immediately after each other.

The sputtered layers stand out against the alternative layers obtainable by means of electrodeposition also by significantly higher material strengths. This is especially for the inlet layer of Bi alloy significant. Here are the strengths typically at 5 to 10 times higher than galvanic layers.

The running layer ( 4 ) can be applied either to a usable in the bearing component steel shell, or bearing shell or on the surface of the bearing component itself.

On the steel shell, the running layer is preferably melted or sintered. On the bearing component, the overlay is preferred applied by thermal spraying. This is in particular the arc wire spraying (LDS) suitable.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102004055228 A1 [0005, 0006]
• DE 102005050374 A1 [0007]
• WO 2006120025 A1 [0008]

Claims (12)

Plain bearing comprising a bearing back ( 5 ), a running layer ( 4 ), a diffusion barrier layer ( 3 ), a sliding layer ( 2 ) and an enema layer ( 1 ), characterized in that the sliding layer ( 4 ) is formed by an Al / Bi alloy having a Bi content of 1.5-21.5 wt .-% Bi and the run-in layer of Bi or a Bi alloy with a Bi content above 90 wt. % is formed. Plain bearing according to claim 1, characterized the Al / Bi alloy has a Bi content of 2-10% by weight Si and the Bi alloy has a Bi content above 98 wt .-% having. Plain bearing according to one of the preceding claims characterized in that the inlet layer is deposited by PVD or sputtered coating. Plain bearing according to one of the preceding claims, characterized in that the running layer ( 4 ) is formed of Cu / Ni, Cu / Sn / Bi alloys or bronze or Al bronze. Plain bearing according to one of the preceding claims, characterized in that the running layer ( 4 ) a thermally deposited coating of the bearing back ( 5 ). Plain bearing according to one of the preceding claims, characterized in that the bearing back ( 5 ) is formed by a usable in the bearing component steel shell or by the surface of the bearing component itself. Plain bearing according to one of the preceding claims characterized in that on the inlet layer a paint or Plastic protective layer is arranged. Method for producing a slide bearing on a component having a composition according to one of the preceding claims, characterized in that both the diffusion barrier layer ( 3 ) as well as the sliding layer ( 2 ) as well as the enema layer ( 1 ) by sputtering on the back of the bearing ( 5 ) or the running layer ( 4 ) are deposited. Method according to claim 8, characterized in that both the diffusion barrier layer ( 3 ) as well as the sliding layer ( 2 ) as well as the enema layer ( 1 ) are deposited in a single sputtering system immediately after each other. Method according to one of claims 8 to 9, characterized in that, the running layer ( 4 ) is applied either to a usable in the bearing component steel shell or on the surface of the bearing component itself. Method according to one of claims 8 to 9, characterized in that, the running layer ( 4 ) is applied directly to the component by an arc wire spraying method (LDS) and the bearing back ( 5 ). Use of sliding bearings according to one of the claims 1 to 7 or obtainable according to one of the claims 8 to 11 in connecting rods, main bearings, camshaft bearings, turbocharger bearings or storage chairs of internal combustion engines.