Stock material or miscellaneous articles – All metal or with adjacent metals – Having composition – density – or hardness gradient
Patent
1991-09-25
1994-04-05
Zimmerman, John
Stock material or miscellaneous articles
All metal or with adjacent metals
Having composition, density, or hardness gradient
428642, 428643, 428646, 428941, 148518, 148527, 148537, 384912, F16C 3312, F16C 3314, C22F 100, B32B 1501
Patent
active
053003683
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase of PCT/DE91/00079 filed Jan. 26, 1991 and based, in turn, upon German national application P 40 03 225.6 filed Feb. 3, 1990 under the International Convention.
FIELD OF THE INVENTION
The invention relates to an overlay of an alloy comprising at least one soft component, particularly in a multilayer plain bearing. The invention also relates to a method for producing such an overlay.
BACKGROUND OF THE INVENTION
Essential requirements on a modern plain bearing are high thermo-mechanical load-bearing capacity and a good slip. The first mentioned feature requires a material having a high thermal stability and strength, while soft materials are to be used for a good slip in the region of slide velocities from 15 m/s and above. These requirements are met particularly by multilayer bearings having a soft overlay and a very strong bearing metal layer of bronze or aluminium materials. The overlay which has a particularly good slip is composed, depending upon the method of manufacture, mostly of lead with 8-20% by weight of tin and 2-6% by weight of copper, while occasionally also up to 10% by weight of copper and other metals may be included. Other overlays are also known, such as SnSb7-alloys or PbIn6-alloys.
Such a plain bearing is described in DE-PS 27 22 144. The overlay of the bearing described therein is lead-based with 10-20% by weight of tin and up to 10% by weight of copper. It has been found that permanent load-bearing capacity may be increased with a higher content of copper and tin. It has also been shown, however, that this overlay may be produced by electro-chemical deposition only with difficulties, because electrolytic solutions containing a high proportion of Sn are unstable and that the increase of permanent load-bearing capacity is followed by increased hardness so that increased abrasion of the shaft may take place. It is therefore desirable to increase the proportion of tin in the overlay.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide an improved overlay for a plain bearing which overcomes drawbacks of prior art overlays and particularly those described above.
Another object of the invention is to provide an overlay, particularly for multilayer plain bearing, which is highly wear-resistant and has also an improved slip.
It is also an object to provide a bearing overlay with which, as far as possible, the improved slip should last for the entire lifetime of the overlay and should have advantageous effect particularly during the running-in time of the plain bearing.
The new overlay should also be simple and capable of being made by conventional methods, such as electro-chemical deposition.
It is also an object of the invention to provide a method for the production of such an improved overlay.
SUMMARY OF THE INVENTION
As regards the overlay, the objects are achieved in that one of the soft components in the overlay is present in a concentration gradient perpendicular to the effective surface of the overlay, namely concentration which decreases with distance from the surface.
As regards the method, the objects are achieved in that a further layer of a soft component is applied on the side of a base overlay and this further layer of a soft component is diffused by thermal treatment at least partly, preferably mostly or entirely into the base overlay so that an overlay is obtained with a concentration gradient of the soft component in which the concentration decreases from the side of the sliding surface to the opposite side of the overlay.
Substances are used as the soft component which can be alloyed and have a good slip, such as tin, antimony, and also lead, indium, thallium etc.
It is known that in modern plain bearings, particularly in multilayer plain bearings, the overlay which has are specially good slip should be preferably only up to 20 .mu.m thick, because with increasing thickness the relative dynamic load-bearing capacity (fatigue strength) of the overlay de
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Translation of German Auslegeschrift 1,077,026, Mar. 1960.
Kubert Michael
Muller Klaus
Dubno Herbert
Glyco-Metall-Werke Glyco B.V. & Co. KG
Wilford Andrew
Zimmerman John
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