621.762Mechanical and antifriction properties of promising copper-based powder materials are examined. The metallographic structure of the new materials is studied. It is shown that copper-based composite materials can be successfully used instead of babbits for friction joints operating at high sliding speeds.Antifriction materials produced by powder metallurgy methods have many advantages over cast alloys [1], namely: antifriction properties can be precisely adjusted by different additives that either interact or do not interact with the base metal, metals can be saved as cutting loses are minimal, energy is saved, and, finally, environmental contamination is minimized.Materials for high-speed friction joints form a specific group among many well-known [1] composite antifriction materials. They operate at sliding speeds V > 15 m/sec; there are also friction joints with sliding speeds reaching 220 to 250 m/sec.The performance of high-speed friction joints is challenged when external loads, which reach P = 7.0-8.0 MPa, additionally affect the contact pair. As a result, they heat up lubricating oil and operating surfaces to 120-140°C. These extreme operating conditions are peculiar to modern high-speed centrifugal equipment: the rotating speed reaches 10,000-12,800 rpm and thus corresponds to sliding speed V = 70-80 m/sec; specific load on the friction pair P = 3.5-7.0 MPa.Babbits B83, B88, and BK, which have high carrying capability, are most widespread bearing alloys among the cast materials [1,2]. For this reason, babbits are used in high-speed friction joints of centrifugal equipment. Considering that babbits have low mechanical properties [1], a babbit layer was placed on a stronger substrate of the base metal of steel 20 bearing in the friction pair.However, actual operating conditions show that none of the babbits can ensure long-term and stable performance of friction joints of centrifugal equipment under extreme conditions despite excellent antifriction properties. At sliding speeds to 100 m/sec, loads on the friction pair to 7 MPa, and temperatures between 120 and 140°C, the mechanical properties of the antifriction babbit layer deteriorate, it is locally melted, and the carrying capability of the bearing consequently decreases.These drawbacks necessitated research efforts intended to find alternatives to babbit alloys, which would combine stable mechanical properties and excellent tribotechnical characteristics in extreme friction conditions of centrifugal equipment. This is the objective of the research.The available literature data [1-5] on the performance of antifriction materials in extreme friction conditions are based on the carrying capability of materials (load multiplied by speed P ⋅ V). This parameter characterizes the range of loads and speeds over which the material can perform appropriately. Hence, the research took into account a possible P ⋅ V range to ensure the maximum compliance of experiments with actual operating conditions of the bearing.

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621.762The composition of secondary structures that develop on the surface of high-temperature composite materials based on steel R6M5F3 scraps with a CaF 2 admixture is investigated under friction at a slip speed of 1 m/sec, load of 7 MPa, and heating temperature of up to 600°C in air. The possibility of predicting and controlling functional properties of bearing materials by selection of initial components that provide for development of friction films of the required thickness and composition is demonstrated.Researchers attempting to increase service requirements of newly engineered entities are faced with the problem of creating new tribotechnical materials with a prolonged service life, while providing energy-and materialresource savings. Methods of powder metallurgy have no alternative for solution of the indicated problem. Nevertheless, powder technology is seeing very little exploitation of its potential, especially in the creation of bearing materials.An insufficiently complete understanding of processes that occur on the friction surface of materials during service under extreme conditions (high temperatures and velocities, heavy loading, and aggressive media), and their effect on the wear resistance of the materials is one of the main obstacles in this path. Continued success in the development of new anti-friction materials and provision for their optimal operating conditions will therefore depend on profound comprehension of the mechanism responsible for friction and wear under the influence of external factors and its accompanying phenomena.Complex mechanical, thermal, and physico-chemical processes, which lead to substantial variations in their properties, occur in the surficial layers of materials subject to friction [1,2]. Here, the wear resistance of the materials is determined not so much by their initial characteristics as by the properties of the films that form on their surfaces. Since the laws established in many studies for friction processes are, as a rule, special in nature, and are valid only within narrow bounds of a specific experiment, study of the above-indicated phenomena, and, primarily, the condition of the surface layer which exerts a decisive influence on the performance of friction couples, is of greatest interest.Kragel'skii [1] and Fedorchenko and Pugina [2] have established that the character and properties of the films that form directly on contacting surfaces (so-called secondary structures) predetermine the serviceability of the antifriction material and friction subassembly as a whole. Secondary structures that form when powder materials are subject to high-temperature friction where liquid lubricants are not serviceable, and solid lubricating components are added to the mixture have not, however, been well understood until now.New high-temperature powder anti-friction materials, for the creation of which wastes from tool, ball-bearing, and die production have come into widespread use as a base [3][4][5], have covincingly demonstrated the steadily high tribotechnical pr...