The resistance during the frictional interaction of polymeric materials with metallic materials is characterized by a significant dependence on the dynamics of the motion inputs. In a metal-polymer friction pair, the static friction resistance during standstill under load depends on the rate of growth of the force causing the relative motion. Tribological tests of selected (polymer-metal) sliding pairs were carried out. The selected polymers were polyurethane (TPU), polysulfone (PSU), and silicone rubber (SI). They interacted with a pin made of normalized C45 steel under unitary pressure p = 0.5 MPa in dry friction conditions at different gradients of the force driving the relative motion (dF/dt = 0.1-20 [N/s]). The static friction coefficient of the selected sliding pairs was determined on the basis of the recorded static friction force values. The test results show a significant influence of the rate of increase in the motion driving force on the values of static friction resistance. This is mainly due to the viscoelastic properties of polymers.

The paper describes the results of metallographic, tribological, and microscopic tests of wire connectors. It was shown that the structure and thickness of the tin layer on the copper element varies greatly. The paper describes the results of tribological investigations for electrical connectors in the initial state and covered with a layer of oxides formed as a result of corrosion. The results of tribological tests have shown a great influence of the oxide layer on friction and wear of tin coatings. The results of friction factor measurements were confirmed by microscopic observations. The tests confirmed that the oxide layer reduces plastic deformation of the tin coating and limits its tribological wear. Due to the brittleness and low adhesion of the oxide layer, friction-induced chipping was observed.