Sliding surface bearing for high loads

Details Sliding surface bearing for high loads Sliding surface bearing for high loads

1989-03-16

1991-09-03

Dean, R.

Stock material or miscellaneous articles

All metal or with adjacent metals

Microscopic interfacial wave or roughness

428614, 428643, 428644, 428650, 428653, 428673, 428674, 384912, B32B 702

Patent

active

050454056

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a sliding surface bearing for high loads, comprising a metal alloy sliding layer, which has physically been applied in a vacuum directly to a metal alloy carrier, particularly to a bearing metal layer, and comprises a base material that contains finely divided particles, which are at least substantially insoluble in the base material at a predetermined operating temperature for which the bearing has been designed.
In conventional sliding surface bearings for heavy loads, an interlayer usually made of nickel is provided between the electrodeposited lead- or tin-base sliding layer which constitutes the sliding surface and the bearing metal layer which carries the sliding layer. That interlayer is intended to ensure an adequate adhesion of the sliding layer to bearing metal layers consisting of an aluminum layer and in case of bearing metal layers made of lead bronze will prevent a diffusion so that a formation of brittle intermetallic phases will be avoided at the operating temperature. Because a premature wear of the soft sliding layer must be expected under heavy loads, e.g., owing to high peak pressures on the lubricating film and small lubricating gaps, elevated operating temperatures or contaminated and aged lubricating oils, there is a risk that the hard interlayer will become exposed at least in part so that the risk of failure will suddenly increase because that interlayer is harder than the bearing metal layer and has no emergency running properties. Besides, the tribological properties of the sliding layer will be deteriorated by a depletion of tin and/or copper owing to (CuNi).sub.x Sn.sub.y phases forming between the sliding layer and the nickel interlayer owing to the known diffusion phenomena.
It is known (German Patent Specification 28 53 724) that the mechanical strength and the wear at elevated temperature can be increased by a formation of metallic sliding or friction layers of a dispersion-hardened composite material by cathode sputtering with a provision of non-metallic inclusions which are very finely divided in soft metallic base material as uniformly as possible. If such dispersion-hardened composite materials are used as a sliding layer of a sliding surface bearing, it will be recommendable to provide an interlayer. Besides, such sliding layers owing to their higher hardness will attack the softer shaft although this must generally be avoided. For these reasons such dipersion-hardened composite materials are not suitable as a sliding layer for sliding surface bearings for high loads.
For this reason it is an object of the invention to provide a sliding surface bearing for high loads, which in spite of having a comparatively soft sliding layer will remain substantially free of wear and unsusceptible to disturbances for the required service life and which will form a sliding surface which has only a minimum tendency to exhibit a mixing by rubbing.
In a sliding surface bearing for high loads which is of the kind described first hereinbefore the invention accomplishes the object set forth in that the particles embedded in the base material have a lower hardness than the base material and a mean particle diameter below 3 .mu.m, the base material of the sliding layer has been crystallized in the form of columns having a preferred orientation at right angles to the sliding surface, and the alloying constituents of the metal alloy of the carrier and of the sliding layer consist of metals which do not form intermetallic compounds at the operating temperature.
Because the crystallites of the base material of the sliding layer are columnar and oriented substantially at right angles to the sliding surface, the wear resistance and the compressive strength of the sliding layer are increased whereas its hardness, which is determined by the exclusively softer embedded particles and by the size of the crystallites of the base material, will not be influenced. Owing to the required fine division of the softer embedded particles in the base material of the sliding layer, to the

REFERENCES:
patent: 3941903 (1976-03-01), Tucker
patent: 4404263 (1983-09-01), Hodes et al.
patent: 4789607 (1988-12-01), Fujita et al.
Thornton, J. A., "Influence of Apparatus Geometry and Deposition Conditions on the Structure and Topography of Thick Sputtered Coatings", Journal of Vacuum Science and Technology, vol. 11, No. 4, Jul./Aug. 1974, 666-670.

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