About wear and average surface temperature of copper or steel contacts at sliding current collection

Abstract

Wear intensity and the average surface temperature of contact between copper and 1020 steel in dry sliding with a contact density higher 100 A/cm2 are defined. It is shown that the temperature decreases linearly along the specimen with an increasing of distance from a contact surface. It is established that copper forms a friction zone with lower average contact surface temperature and with lower wear intensity in comparison with those of 1020 steel. It is caused by the lower local shear stability of copper comparing with that of 1020 steel. The explanation of this fact is offered on the basis of idea of low copper shear stability (i.e. copper high plasticity) that leads to easy relaxation of mechanical stresses in the field of stress concentrators. In this case, the surface layer is deformed locally at the low structural level and the low speed of structural defects formation is manifested. Rather high fatigue resistance of a surface layer takes place as a result. These factors and high heat conductivity of copper cause high shear stability of a surface layer at the macro-scale structural level that promotes weak heating and high wear resistance. Iron (unlike copper) has rather low heat conductivity and higher local shear stability. It leads to more difficult tension relaxation in a surface layer, as well as average temperature increasing and higher speed of deterioration.