ANTIFRICTION MATERIALS AND PRODUCTS ON METAL BASIS

Abstract

An analysis of technologies and properties of antifriction materials based on metals is carried out, as a result of which, the possibility of their production by powder metallurgy methods is substantiated. It is shown that the main characteristic property of these materials is the low coefficient of friction, which should be f = 0,001...0,1 in the presence of a lubricant and f = 0,11...0,3 under conditions of boundary and dry friction. Materials with a coefficient of friction f>0,3 are considered contact or brake materials. It is shown that the performance characteristics of antifriction materials vary over a wide range; sliding speed: V =

= 0,001...300,0 m/s, load P = 0,001...150,0 MPa and more, working temperature: from cryogenic to 1000⁰C and above.

As a resuit of complex theoretical and experimental studies, the features of antifriction powder alloy structurization are revealed. According to these features it is expedient to apply alloys with two-phase structure with easy and average loadinge, as well as for friction knots which work in oil medium. In more severe conditions of the working knots including the conditions of dry friction, it is expedient to apply a powder alloy with a three-phase structure. The deperdence of the contact pressure, bearing ability, wear resistance and factor of friction on stereometric powder materials of antifrictional designation is established. The role of each structural component in the course of friction is defined and their parameters are substantiated. It is shown that with optimum hard lubrication, the formation of the secondsry structure is guaranteed by volumetric expansion coefficients of structural components F. of V.E.m>E.of V.E.f.g. The dependence of the bearing ability, wear resistance and the friction coefficient on the exploitation duration and the porosity of wear - resistant powder materials of antifriction purpose is established. The technology of their obtaining is developed.

The expediency of compacting wear - resistant antifriction powder materials by extrusion for working under the conditions of heavy loading at dry friction is justified. The mechanism of the extrusion process of powder materials containing hard lubricating substances in their structure is revealed.