Composite bearing material with a metallic support layer made of steel

Abstract

A sliding bearing composite material (2) comprising a metallic support layer (4) made of steel and a porous carrier layer (6) made of sintered particles (8) of bronze applied thereto, and a lead-free sliding layer (12) forming a sliding surface (14) for a sliding partner, comprising a plastic-based sliding layer material (10) wherein the sliding layer material (10) comprises PEEK as a matrix-forming plastic component, and comprising a lubricant and a hardening component, wherein the weight percent proportion of the lubricant and the hardening component, based on the mass of the sliding layer material (10), is each 5–15 wt.%, characterized in that the steel support layer (4) comprises a stainless steel layer (16) made of stainless steel with at least 11 wt.-% chromium is, wherein the stainless steel layer is formed from a cold-rolled strip of a high-alloy steel namely X2CrNi19-11 steel or X2CrNi18-9 steel and has only on its side facing the porous support layer (4) a thin copper-based layer (18) of a thickness of 20 - 60 µm rolled onto the stainless steel layer (16), against which particles (8) of the porous support layer (6) are sintered.

Description

Changed description

[0001] The invention relates to a sliding bearing composite material with a metallic support layer made of steel and with a porous carrier layer made of sintered bronze particles applied thereto, and with a lead-free sliding layer forming a sliding surface for a sliding partner, comprising a plastic-based sliding layer material, wherein the sliding layer material comprises PEEK as a matrix-forming plastic component, and with a lubricant and with a hardening component, wherein the weight percent proportion of the lubricant and the hardening component, based on the mass of the sliding layer material, is each 5-15 wt.%.

[0002] Composite sliding bearing materials of the aforementioned type, with PEEK as the polymer base and the matrix-forming polymer component of the sliding layer material, are known, in particular from DE 102 26 266 C. They have proven their worth with regard to their high-temperature load-bearing capacity and high-temperature resistance, even above 180 °C, and with regard to their chemical resistance. Good tribological properties can be achieved by adding solid lubricants and hardening components to the sliding layer material. The porous support layer holds and supports the sliding layer material, and the sintered structure of the porous support layer, composed of sintered particles, also serves to dissipate the frictional heat generated.

[0003] US 5,643,683 also discloses a generic sliding bearing composite material with a galvanically copper-plated steel backing.

[0004] DE 40 38 819 A1 discloses a non-generic, pure metallic sliding bearing composite material, particularly for the production of half-bearing shells, comprising a support layer of austenitic stainless steel with a high coefficient of thermal expansion, the oxide film of which was removed by cathodic electrolysis in a hydrochloric acid bath with cobalt chloride, forming a thin, 2 µm thick bonding layer of cobalt or, alternatively, nickel. Subsequently, a thin copper layer with a thickness of 1–20 µm, and 10 µm in the exemplary embodiment, was electrolytically deposited. Finally, copper-lead alloy powder with a particle size of 100 mesh was sprinkled onto this layer and sintered to form a metallic sliding layer.

[0005] DE 44 11 762 A1 describes a metallic sliding bearing material consisting of a sliding layer made of copper-zinc wrought alloy, which is inseparably bonded to a support layer made of steel or stainless steel by roll cladding.

[0006] Furthermore, in REICHELT, Stephan [et al.]; Application-oriented functional materials using roll cladding. In: Rolling of flat products. Berlin: Springer, 2017. pp. 68-82. - ISBN 978-3-662-48090-8, the application of roll cladding for bonding the sliding layer of a sliding bearing to an underlying support layer is described.

[0007] Plain bearing elements manufactured from generic bearing composite materials of the type mentioned above, such as butt-rolled bushings or flanged bushings, are typically pressed into metal housing openings, preferably in such a way that a tight fit can be maintained during operation. When the plain bearing elements interact in sliding contact with friction or sliding partners, typically supported shafts or shaft or articulated journals, during operation, they are exposed to media, particularly lubricants or penetrating environmental media, from the interface to the friction or sliding partner, which can corrode the plain bearing element. Chemical attack on the plain bearing composite material and the plain bearing element manufactured from it can also originate from the rear side of the plain bearing element, i.e., from the components surrounding or forming a housing opening.If corrosion occurs on the back of the metallic support layer, this can negatively affect the dimensional accuracy of the bearing.

[0008] The present invention is based on the objective of improving the long-term serviceability of a sliding bearing element formed from a sliding bearing composite material of the type mentioned at the outset in a bearing location.

[0009] This problem is solved according to the invention, starting from a sliding bearing composite material of the type mentioned, by the fact that the steel support layer is a Stainless steel layer made of rust-free stainless steel with at least 11 wt% chromium, wherein the stainless steel layer is formed from a cold-rolled strip of a high-alloy steel namely X2CrNi19-11 steel or X2CrNi18-9 steel, and only on its porous The side facing the carrier layer should be on the stainless steel layer. roll-plated thin layer on a copper base of a thickness of 20 - 60 µm, against which particles of the porous The carrier layer is sintered on.

[0010] Because the support layer is made of stainless steel, it can be combined with virtually any surrounding metallic material to form a bearing surface without corrosion occurring on the back of the sliding element over time and impairing the function, dimensional stability, and thus the long-term serviceability of the sliding bearing element. Until now, it has not been possible to sinter bronze-based sintered layers onto stainless steel layers because stainless steel is so stable due to a protective chromium oxide layer that it cannot be reduced by conventional processes. According to the invention, by applying a thin, roll-clad copper-based layer to one side of the stainless steel layer, a bronze-based support layer with high strength and good bonding to the support layer can be sintered onto it.Overall, a composite material for sliding bearings is achieved that is characterized by high fatigue strength and excellent corrosion resistance, yet can be manufactured economically.

[0011] Furthermore, it proves advantageous if the stainless steel layer is formed from a cold-rolled strip of steel with an elongation at break of at least 45%. This This enables the roll plating of the stainless steel layer with the copper-based layer.

[0012] Furthermore, it proves advantageous if the The stainless steel layer is formed from a cold-rolled strip of steel that, after a sensitization treatment of 15 minutes at 700°C followed by cooling in air, exhibits resistance to intergranular corrosion. With such a steel, there are no problems resulting from the sintering of bronze particles to form the porous substrate layer.

[0013] The stainless steel layer is formed from a cold-rolled strip of a high-alloy steel with 18.0-20.0 wt.% chromium and 10.0-12.0 wt.% nickel, namely an X2CrNi19-11 steel.

[0014] Alternatively, the stainless steel layer is formed from a cold-rolled strip of a high-alloy steel with 17.0-19.0 wt.% chromium and 8.0-10.0 wt.% nickel, namely an X2CrNi18-9 steel.

[0015] The present invention does not preclude the inclusion of one or more other thermoplastics in the sliding layer material in addition to PEEK as the matrix-forming plastic component. However, their proportion should not exceed 20 wt.%, and in particular not exceed 10 wt.%, of the proportion of the plastic component in the sliding layer material. Preferably, the plastic component is composed entirely of PEEK.

[0016] Furthermore, it proves advantageous if the lubricant of the sliding layer material comprises particles of zinc sulfide and / or barium sulfate.

[0017] Furthermore, it proves advantageous if the hardening component of the sliding layer material comprises particles in the form of titanium dioxide and additionally carbon fibers. With regard to the material composition of the sliding layer material, reference is made to the applicant's aforementioned DE 102 26 266 C, the content of which is incorporated into the present application to that extent.

[0018] To produce the composite of support layer and carrier layer, it is proposed that a bed of sintered bronze particles be sintered onto the support layer at temperatures of 800–920° Celsius under a protective atmosphere of nitrogen and hydrogen as a reducing agent. This process breaks down oxide protective layers, allowing pure metallic surfaces to come into contact and sinter together under heat.

[0019] The plastic-based sliding layer material can then be impregnated into the three-dimensionally porous carrier layer in a manner known per se.

[0020] Further details, features, and advantages of the invention will become apparent from the attached claims and from the drawing and subsequent description of a preferred embodiment of the invention. The drawing shows: Fig. 1 A schematic sectional view of a sliding bearing composite material according to the invention.

[0021] Fig. Figure 1 shows a sliding bearing composite material, designated by reference numeral 2, comprising a metallic support layer 4 made of stainless steel and a porous carrier layer 6 made of sintered bronze particles 8. A sliding layer material 10 with PEEK as the matrix-forming polymer component is impregnated in the carrier layer. This material extends beyond the porous carrier layer 6 and forms a sliding layer 12 with a sliding surface 14 for a sliding partner. The sliding layer 12 and the sliding layer material 10 further comprise at least one lubricant and at least one hardening component of the type mentioned above.

[0022] The metallic support layer 4 comprises a stainless steel layer 16 and a thin copper-based layer 18, typically a pure copper layer, applied thereon by roll cladding. In this way, it is possible to sinter bronze particles 8 onto the support layer 4.

Claims

[1] Plain bearing composite material (2) with a metallic support layer (4) made of steel and with a porous carrier layer (6) made of sintered particles (8) made of bronze applied thereon, and with a lead-free sliding layer (12) forming a sliding surface (14) for a sliding partner, with a plastic-based sliding layer material (10), wherein the sliding layer material (10) comprises PEEK as a matrix-forming plastic component, and with a lubricant and with a hardening component, wherein the weight percentage of the lubricant and the hardening component based on the mass of the sliding layer material (10) is 5 - 15 wt.% each, characterized bythat the support layer (4) made of steel is a stainless steel layer (16) made of stainless steel with at least 11 wt.% chromium, wherein the stainless steel layer is formed from a cold-rolled strip made of a high-alloy steel, namely X2CrNi19-11 steel or X2CrNi18-9 steel, and only on its side facing the porous carrier layer (4) has a thin layer (18) based on copper with a thickness of 20 - 60 µm, roll-plated onto the stainless steel layer (16), against which particles (8) of the porous carrier layer (6) are sintered. [2] Plain bearing composite material according to claim 1, characterized by that the stainless steel layer is formed from a cold-rolled strip of steel with an elongation at break of at least 45%. [3] Plain bearing composite material according to claim 1 or 2, characterized bythat the stainless steel layer is formed from a cold-rolled strip of a steel which, after a sensitisation treatment of 15 minutes at 700°C followed by cooling in air, is resistant to intergranular corrosion. [4] Plain bearing composite material according to one or more of the preceding claims, characterized by that the lubricant comprises particles of zinc sulfide and / or barium sulfate. [5] Plain bearing composite material according to one or more of the preceding claims, characterized by that the hardening component comprises particles in the form of titanium dioxide and additionally carbon fibers. [6] Plain bearing composite material according to one or more of the preceding claims, characterized byin that, in order to apply the carrier layer (6) to the support layer (4), a bed of sintered particles (8) made of bronze is sintered onto the support layer at temperatures of 800 - 920° Celsius and under a protective gas atmosphere of nitrogen and hydrogen as a reducing agent.

Images