Sliding bearing composite material
Patent Information
- Application Number
- EP2025701093
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-03-01
- Filing Date
- 2025-01-14
- Publication Date
- 2026-01-14
AI Technical Summary
Existing plain bearing materials lack improved tribological properties, particularly under conditions of insufficient lubrication and high loads, and there is a need for a lead-free alternative with enhanced wear resistance and scuffing resistance.
A plain bearing composite material comprising a metallic support layer and a bearing metal layer made of sintered bronze particles and Fe3P particles, with specific copper alloy compositions and controlled particle sizes, which are sintered onto the support layer to enhance tribological properties.
The composite material exhibits significantly increased abrasion resistance and maintains strength, with improved emergency running properties and ductility, even under high loads and insufficient lubrication, while being lead-free.
Smart Images
Figure EP2025050788_04092025_PF_FP_ABST
Abstract
Description
[0001] Title: Plain bearing composite material
[0002] Description
[0003] The invention relates to a plain bearing composite material, with a metallic support layer and a bearing metal layer made of sintered particles of a sintered material applied to the support layer.
[0004] Plain bearing composite materials and plain bearings made from them are widely known. For example, DE 10 2004 008 630 Al discloses a plain bearing material with a metallic support layer and a metallic, lead-free bearing metal layer made of densely sintered tin bronze powder particles with bismuth additives.
[0005] EP 2 166 117 A1 discloses a lead-free copper alloy containing 1-15 wt.% tin, 0.5-15 wt.% bismuth, and 0.05-5.0 wt.% silver. It is designed to form a BiAg eutectic. The material can optionally contain hard particles such as Fe3P, Fe2P, FeB, NiB, or AlN.
[0006] From EP 2 322 676 Al, a copper-tin-bismuth based sliding material is also known, which can optionally contain hard particles such as Fe3P, Fe2P, FeB and Fe2B, AlN, NiB, Mo2C, Al2O3.
[0007] The present invention is based on the object of providing a plain bearing composite material of the type mentioned above with improved tribological properties.
[0008] This object is achieved according to the invention by a plain bearing composite material having the features of claim 1. The plain bearing composite material comprises a metallic support layer, in particular made of steel or a copper alloy, and a bearing metal layer made of sintered, in particular densely sintered, particles of a sintered material, in particular sintered powder, applied, in particular directly, to the support layer. The sintered material comprises bronze particles, in particular bronze powder, and Fe3P particles (triiron phosphide particles), in particular FeaP powder. In this respect, the sintered material is a particle mixture, in particular a powder mixture, of particles of various types and compositions. In particular, the sintered material consists of bronze particles and FeaP particles. The proportion of FeaP particles in the sintered material is 0.5 - 5.0 wt.%. The bronze particles consist of a copper alloy with the following composition:
[0009] 8.0 - 12.0 wt% Sn (tin)
[0010] 6.0 - 11.0% by weight Bi (bismuth)
[0011] 1.0 - 4.0 wt% Zn (zinc)
[0012] - optionally P (phosphorus) up to a maximum of 0.1% by weight, in particular up to 0.07% by weight, more particularly up to 0.05% by weight;
[0013] - optionally impurity-related elements in each case up to a maximum of 0.10 wt.%, preferably up to a maximum of 0.05 wt.%, more preferably up to a maximum of 0.04 wt.%, and in total up to a maximum of 0.5 wt.%;
[0014] - Rest copper.
[0015] The proposed plain bearing composite material exhibits improved tribological properties. Specifically, it was discovered within the scope of the invention that the combination of bronze particles of the claimed copper alloy (with a comparatively high bismuth content and a mandatory, but comparatively low, zinc content) and FeaP particles can produce a lead-free bearing metal layer with high scuffing resistance and, at the same time, high wear resistance. In particular, it has surprisingly been found that even the addition of small amounts of FeaP leads to a significant increase in wear resistance without significantly impairing the strength within the bearing metal layer and, in particular, the emergency running properties of the plain bearing composite material.In this respect, a plain bearing material is provided that exhibits significantly increased abrasion resistance compared to conventional plain bearing materials, especially under insufficient lubrication and high loads. Furthermore, it has been discovered that the addition of small, but not excessive, amounts of zinc can achieve comparatively good ductility despite a high bismuth content. It is assumed that the addition of zinc in the stressed area (at least 1.0 wt.% and a maximum of 4.0 wt.%) contributes to limiting wetting of the grain boundaries by bismuth and thus increasing ductility.
[0016] The bearing metal layer is in particular lead-free (i.e. without active addition of lead as an alloying element and with a maximum of 0.10 wt.% of any contamination-related residues of lead).
[0017] The bearing metal layer, in particular the copper alloy, is in particular silver-free (ie without active addition of silver as an alloying element and with a maximum of 0.10 wt.%, preferably a maximum of 0.05 wt.% of any impurity-related residues of silver).
[0018] Preferably, the sintered material consists of: 0.5-5.0 wt.% FeaP particles,
[0019] - optionally impurities totalling up to 1.0% by weight, in particular up to 0.5% by weight, further in particular up to 0.1% by weight,
[0020] - Remaining bronze particles.
[0021] It proves to be particularly advantageous if the proportion of FeaP particles in the sintered material is 1.0 - 5.0 wt.%, in particular 1.5 - 4.5 wt.%, further in particular 1.8 - 4.2 wt.%.
[0022] Furthermore, it proves to be advantageous if an average particle diameter (D50) of the Fe3P particles is less than 45 pm, preferably less than 30 pm, more preferably less than 20 pm, more preferably less than 15 pm, and more than 5 pm, preferably more than 8 pm, more preferably more than 10 pm.
[0023] The mean particle diameter (D50) is understood here as the size value in pm for which 50 wt.% of a batch in question has a larger particle diameter or is heavier, and 50 wt.% has a smaller particle diameter or is lighter. It is therefore a mean particle diameter.
[0024] The particle diameter can be determined in particular by means of laser diffraction. Preferably, the particle diameter is determined according to ISO 13320:2020-01. In particular, the particle diameter can be determined by means of laser light scattering using a "laser scattering
[0025] Particle Size Distribution Analyzer", e.g. the "Partica LA-960V2" from Horiba Scientific.
[0026] Preferred compositions of the copper alloy are set out in the further patent claims. In particular, the alloy consists of the alloying constituents specified in the patent claims, optionally with impurity elements in a maximum of 0.10 wt.% each, and a maximum of 0.5 wt.% in total.
[0027] The copper alloy preferably contains 6.0 - 10.5 wt.% bismuth, more preferably 6.0 - 10.0 wt.% bismuth, more preferably 6.0 - 9.5 wt.% bismuth, more preferably 6.0 - 9.0 wt.% bismuth.
[0028] As mentioned above, it is assumed that the addition of at least 1.0 wt.% and a maximum of 4.0 wt.% zinc to the copper alloy can reduce wetting of the grain boundaries by bismuth and thus increase ductility. In this context, it has proven particularly advantageous if the copper alloy contains at least 2.0 wt.% and a maximum of 4.0 wt.% zinc, in particular at least 2.5 wt.% and a maximum of 4.0 wt.%, and further in particular at least 2.5 wt.% and a maximum of 3.5 wt.%.
[0029] The copper alloy preferably contains 8.5-11.5 wt.%, more preferably 9.0-11.0 wt.%, tin. The copper alloy is particularly preferably a CuSn1 OBi7Zn3 alloy.
[0030] Furthermore, it proves advantageous if the grain size distribution (particle size distribution) of the bronze particles has a characteristic grain size (particle size) of 40–75 pm, especially 40–60 pm. This promotes a bearing metal layer with homogeneous strength and high load-bearing capacity, especially in combination with an average particle diameter of the FeaP particles of less than 45 pm and more than 5 pm.
[0031] The characteristic particle size is the size value in pm for which 36.79 wt.% (1 / e wt.%, where e is Euler's number) of a given batch has a larger particle size or is heavier and 63.21 wt.% has a smaller particle size or is lighter. The particle size distribution is determined by sieve residue tests for a given batch. The result of sieve residue tests can be given either (non-cumulatively) in wt.% for a particular mesh size or cumulatively according to DIN ISO 4497 (so that for the smallest mesh size, almost 100 wt.% is determined). The cumulative sieve residue can be given by a distribution function, namely
[0032] R = cumulative sieve residue t = mesh size r| = characteristic grain size ß = shape parameter (=slope of the straight line in logarithmic plot according to DIN 66 145 ).
[0033] A preferred grain size distribution is characterized by a shape parameter ß of 1.2 - 2.6 and a characteristic grain size in the range specified above.
[0034] The bronze particles can be spherical. They can also have a bulbous shape, deviating from the regular spherical shape, but without edges or undercuts.
[0035] To produce a plain bearing composite material as described above, for example, the bronze particles and the FeaP particles can be mixed, in particular homogeneously, and this particle mixture (sintered material) can then be sintered onto the support layer, for example a steel strip, in a basically known manner.
[0036] For example, a method for producing such a plain bearing composite material may comprise the following steps: - providing the support layer;
[0037] - Providing the sintered material;
[0038] - Application, in particular sprinkling, of the sintered material onto the support layer;
[0039] - Pre-sintering of the sintered material or the particles of the sintered material, in particular at temperatures between 750 and 850 °C;
[0040] (Optional): Rolling the layer of pre-sintered sintered material, in particular to close pores;
[0041] - post-sintering, in particular dense sintering, of the pre-sintered sintered material, in particular at temperatures between 780 and 880 °C;
[0042] (Optional) : Rolling the post-sintered layer.
[0043] It is also conceivable, in principle, to perform only one sintering step. In this respect, the process can include sintering, particularly dense sintering, of the sintered material particles after applying the sintered material to the support layer, particularly at temperatures between 750 and 880 °C.
[0044] Advantageously, an average layer thickness of the bearing metal layer (measured orthogonally to that surface of the support layer to which the bearing metal layer is applied) is 0.2-1.2 mm, preferably 0.2-1.0 mm, more preferably 0.2-0.6 mm.
[0045] It is conceivable that the bearing metal layer made from the sintered material forms the sliding layer, i.e. the layer which interacts with a sliding partner, e.g. a shaft, during intended use. It is also conceivable that the plain bearing composite material additionally has a running layer applied, in particular directly, to the bearing metal layer. The running layer can be, for example, a polyamide layer, a polyamide-imide layer, a sputter layer, in particular a PVD layer, or an electroplated layer. The running layer is preferably a PAI layer (polyamide-imide layer).
[0046] The above-described sliding bearing composite materials can be used in particular as sliding bearing elements. In this respect, the invention also encompasses a sliding bearing element made from or comprising a sliding bearing composite material described above.
[0047] The plain bearing element can be, for example, a sliding plate, a sliding strip, a plain bearing shell, a plain bearing bush or flanged bush. The sliding element can also be a thrust ring or a thrust washer. The sliding element can also typically be rolled cylindrical bushes or half-shell-shaped plain bearing elements that are manufactured using the plain bearing composite material. The plain bearing composite material can also be used to manufacture flanged bushes or pot bushes or flat and spherical plain bearing elements. Particularly advantageous uses of the plain bearing composite material are thrust washers. In this respect, the sliding element can in particular be a thrust washer.The invention also relates to a sintered material, in particular for producing a bearing metal layer on a metallic support layer, further in particular for forming a plain bearing composite material as described above. The sintered material comprises bronze particles, in particular bronze powder, and FeaP particles, in particular FeaP powder, wherein the proportion of FeaP particles in the sintered material is 0.5-5.0 wt.%, preferably 1.5-4.5 wt.%, further preferably 1.8-4.2 wt.%, and wherein the bronze particles consist of a copper alloy with the following composition:
[0048] 8.0 - 12.0 wt.%, in particular 9.0 - 11.0 wt.%, tin; 6.0 - 11.0 wt.%, in particular 6.0 - 10.0 wt.%, further in particular 6.0 - 9.0 wt.%, bismuth;
[0049] 1.0-4.0 wt.%, in particular 2.0-4.0 wt.%, further in particular 2.5-4.0 wt.%, further in particular 2.5-3.5 wt.%, zinc;
[0050] - optionally phosphorus up to a maximum of 0.1% by weight, in particular up to 0.07% by weight, more particularly up to 0.05% by weight;
[0051] - any impurity elements up to a maximum of 0.10% by weight each and a maximum of 0.5% by weight in total;
[0052] - Rest copper.
[0053] The optional features and advantages described above with regard to the plain bearing composite material can also be used to further develop the sintered material, so that, to avoid repetition, reference is made to the above disclosure. The invention is explained in more detail below with reference to the figures. They show:
[0054] Fig. 1 simplified schematic representation of an exemplary embodiment of a plain bearing composite material in a sectional view;
[0055] Fig. 2 simplified schematic representation of a further exemplary embodiment of a plain bearing composite material in a sectional view;
[0056] Fig. 3 Diagram to explain the wear behavior of plain bearing elements made of different plain bearing composite materials; and
[0057] Fig. 4 Diagram to explain the emergency running properties of the plain bearing elements considered in Figure 3.
[0058] Figure 1 shows a schematic sectional view of an embodiment of a plain bearing composite material, which is designated overall by the reference numeral 10.
[0059] The plain bearing composite material 10 comprises a metallic support layer 12, typically made of steel or a copper alloy, and a bearing metal layer 14 made of sintered particles of a sintered material 16, applied directly thereto in the example. The layer thicknesses shown in the figures are merely exemplary and not to scale.
[0060] As mentioned above, in order to produce the plain bearing composite material 10, a particle layer of the sintered material 16 can be applied to the support layer 12 and then sintered on.
[0061] Figure 2 shows a schematic sectional view of a further embodiment of a plain bearing composite material 10, in which a further running layer 18 is applied to the bearing metal layer 14. The running layer 18 can, for example, be a polyamide-imide (PAI) layer.
[0062] The following table lists exemplary and preferred compositions of the sintered material 16. Pure bronze serves as a reference.
[0063] Figure 3 shows the result of a wear test and Figure 4 the result of an emergency running test on plain bearing elements made from a plain bearing composite material 10 according to Figure 1. In concrete terms, discs were made from a
[0064] Plain bearing composite material 10 according to Figure 1 (i.e. without additional running layer 18) was produced, wherein the bearing metal layer 14 was produced from the sintered materials of Examples 1 and 2 and the reference. For this purpose, the sintered material 16 was sprinkled onto a steel strip (support layer 12) and pre-sintered in a first sintering step at temperatures between 750 and 850 °C. A rolling process was then carried out in order to compact the pre-sintered layer and in particular to close larger pores. A second sintering step was then carried out in which the pre-sintered sintered material 16 was densely sintered at temperatures between 780 and 880 °C. A layer thickness of the bearing metal layer 14 is, for example, 0.3 mm.
[0065] The wear resistance was then determined in a rotation test (disk test), in which a steel test specimen made of 100Cr6 was pressed against the bearing metal layer 14 of the plain bearing discs with a predetermined load, and the disc was rotated under this load. Specifically, 9,000 start-stop cycles were performed, with the disc speed being changed according to a predetermined pattern (ramp) in each start-stop cycle.
[0066] The detailed test parameters of the rotation test are given in the table below.
[0067] As with a comparison of wear values after 9000
[0068] As becomes clear during the cycles, even a comparatively small addition of FeaP particles leads to a significant reduction in wear.
[0069] Figure 4 shows the result of an emergency running test (seizure test) in which a steel test specimen was pressed with a test force of 1.5 kN (0.75 MPa) against the bearing metal layer 14 of the plain bearing disk rotating at 1000 revolutions / min and the time until seizure occurred was measured.
[0070] As can be seen from Figure 4, the emergency running properties of the plain bearing composite materials according to the invention with Fe3P-
[0071] Particles slightly reduced compared to pure bronze, but still within an acceptable range.
Claims
Patent claims 1. A plain bearing composite material (10) comprising a metallic support layer (12), in particular made of steel or a copper alloy, and a bearing metal layer (14) made of sintered particles of a sintered material (16), applied in particular directly to the support layer (12), characterized in that the sintered material (16) contains bronze particles and FeaP particles, wherein the bronze particles consist of a copper alloy of the following composition: 8.0 - 12.0 wt.% tin 6.0 - 11.0 wt.% bismuth 1.0 - 4.0 wt.% zinc - optionally phosphorus up to a maximum of 0.1% by weight, in particular up to a maximum of 0.07% by weight, more particularly up to a maximum of 0.05% by weight; - any impurity elements up to a maximum of 0.10% by weight each and a maximum of 0.5% by weight in total; - Rest copper, whereby the proportion of FeaP particles in the sintered material (16) is 0.5 - 5.0 wt.%.
2. Plain bearing composite material (10) according to claim 1, wherein the proportion of FeaP particles in the sintered material (16) is 1.0 - 5.0 wt.%, in particular 1.5 - 4.5 wt.%, further in particular 1.8 - 4.2 wt.%.
3. Plain bearing composite material (10) according to claim 1 or 2, wherein an average particle diameter of the FeaP particles is less than 45 pm, preferably less than 30 pm, more preferably less than 20 pm, more preferably less than 15 pm, and more than 5 pm, preferably more than 8 pm, more preferably more than 10 pm.
4. Plain bearing composite material (10) according to one of the preceding claims, wherein the copper alloy contains 6.0 - 10.0 wt.%, preferably 6.0 - 9.0 wt.%, of bismuth.
5. Plain bearing composite material (10) according to one of the preceding claims, wherein the copper alloy contains 2.0 - 4.0 wt.%, in particular 2.5 - 4.0 wt.%, further in particular 2.5 - 3.5 wt.%, of zinc.
6. Plain bearing composite material (10) according to one of the preceding claims, wherein the copper alloy contains 9.0 - 11.0 wt.% tin.
7. Plain bearing composite material (10) according to one of the preceding claims, wherein the copper alloy is a CuSnl OBi7Zn3 alloy.
8. Plain bearing composite material (10) according to one of the preceding claims, wherein the grain size distribution of the bronze particles has a characteristic grain size of 40 - 75 pm, in particular of 40 - 60 pm.
9. Plain bearing composite material (10) according to one of the preceding claims, further comprising a running layer (18), in particular a polyamide-imide layer, applied, in particular directly, to the bearing metal layer (14).
10. Plain bearing element, in particular thrust washer, made of a plain bearing composite material (10) according to one of the preceding claims.
11. Sintered material for producing a bearing metal layer (14) of a Plain bearing composite material (10) according to one of claims 1 to 9.