A new experimental procedure of evaluating the friction coefficient in elastic and plastic regions

The coefficient of friction is one of the parameters that show the amount of resistance to relative motion of two sliding objects. From the basic assumptions of the adhesive theory of friction, the value of the coefficient of friction will almost be equal to 0.2. In high vacuum conditions experimentally determined values of the coefficient of friction of six or more have been recorded, which clearly cannot be explained by simple model. It is this discrepancy between experiment and theory that led to the junction growth theory. In this research a new experimental investigation is described in which the coefficient of friction for steel–aluminum contact surface has been found. This test was conducted by using a testing machine on the basis of twist-compression test. The results showed that the coefficient of friction of steel–aluminum interface started at an initial value of 0.2 and increased almost to 0.8 in the elastic region and then decreased to the value of 0.6 in the plastic region.