Railway Research Institute, Moscow, Russia:

A. E. Mironov, Leading Researcher
I. S. Gershman, Head of Laboratory of Non-Ferrous Metals and Tribology, e-mail: isgershman@gmail.com
E. G. Kotova, Post-Graduate Student

There was made a comparison of the impact of degassing and modifying properties of various reagents on the properties and structure of the cast antifriction aluminum-tin alloys. As of now, most of the aluminum-tin alloys are used as a sliding layer of the double-layer slider bearings. The design of such bearings represents a rugged steel case joint by rolled anti-friction material. The first step in obtaining the molding material is casting. The cast anti-friction aluminum-tin alloys are working out as a replacement of anti-friction bronzes in the shaft-bearing friction nodes. Cast bearings can be broken not only in result of wear, but of fatigue damages as well. In this connection, mechanical properties of alloys for bearing are important no less than the anti-friction ones. Not only composition of alloys affect their mechanical properties, but melting and cast technologies as well. Impact of these technological operations on chemical composition, microstructure and alloy properties is demonstrated. It has been revealed an advantage of a Zernolit-2 (Зернолит-2) degasser and modifier over preparations of the Schafer company. It is noted that use of degassers and modifiers allows to improve mechanical properties and hot-shortness of cast anti-friction aluminum-tin alloys. It is demonstrated that the Zernolit-2 degasser and modifier guarantees much more durability and plasticity and less hot-shortness of the alloy than the Schafer preparations do. Using Zernolit-2 degasser and modifier provides heightened slag formation which means that it surpasses Schafer preparations in the alloy cleaning of impurities. Mechanisms of degassing and modifying influence upon the properties and structure of alloy are discussed. It is pointed out that significant size reduction of aluminum grains and the soft structural component inclusions additionally increase mechanical properties of the cast anti-friction aluminum-tin alloys when using modifiers and degassers.

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