Laws of the Sliding Friction of R6M5 Steel on Grade 45 Steel in the Litol-24 Lubricant Medium with Dispersed Graphite Particles

The sliding friction of R6M5 steel on grade 45 steel in the load range from 0 to 700 N in the medium of a plastic Litol-24 lubricant modified with dispersed graphite particles is studied. The dependence of the frictional force on the normal force is found to have a piecewise linear form with two linear sections. Both classical and generalized versions of the Amonton–Coulomb law are shown to be valid for the materials under study. Graphite particles are found to improve the antifriction characteristics in the load range 442–614 N and to increase the critical load from 390 to 540 N and the bearing capacity of the lubricating layer. A mathematical model is proposed to describe the viscosity of plastic lubricants with dispersed additives.