Dependence of the friction coefficient and wear resistance of copper-bearing modified cast irons on their mechanical properties

Abstract

1. The quantity of worn-away material of a cast iron friction pair is proportional to the work done by friction forces; under steady-state wear conditions it is proportional to the friction time, i.e., to the friction path. This relationship is a characteristic of the steady-state stage of the process of wear; it also provides an indirect proof that the experimental technique used was correct and that the testing machine [3] functioned properly. 2. The rate of wear of a cast iron friction pair at a given sliding speed and normal load is determined by the mechanical properties of the rubbing parts, particularly by the ratio of the hardness of the stationary parts (testing blocks) to that of the rotating part (ring): Increasing the ratio HBo∶HBk leads to an increase in the extent of wear. 3. The extent of wear (by weight) of a cast iron friction pair is a linear function of the friction force and the friction coefficient. Under steady-state conditions the sliding friction coefficient depends on the physico-mechanical properties of the rubbing materials; increasing the hardness, strength and other mechanical properties of cast iron parts causes a reduction in friction coefficient and, consequently, in the degree of wear. 4. When the friction pair components are made of similar cast irons, the total linear wear is proportional to the extent of wear measured in terms of weight losses, a similar relationship existing between the total degree of wear (linear and by weight) and friction coefficient. This rule does not hold for friction pairs comprising dissimilar cast iron components.