Effect of the phase composition of steel-based composites on the electrical resistance of the friction zone under conditions of current collection

The current-voltage diagram of the electric contact zone and the wear rate of sintered composites based on ball-bearing wastes steel (1.5% Cr) and Hadfield steel (13% Mn) at sliding over quenched steel (0.45% C) are investigated with tin and lead incorporated in the friction zone. It is established that melting is accompanied by a significant decrease in the electrical resistance which causes the nonlinearity of the current-voltage diagram of the contact. An increase in the strength of the contact layers manifested through the increased wear resistance is simultaneously observed. Based on the Ohm law, it is qualitatively demonstrated that the nonlinearity is caused by the change of the true area of electrical contact. Results of analogous experiments for composites that do not contain lead or tin are presented. It is established that the electrical conductivity and the strength of the surface layer sharply decrease for such change of the phase composition.