Effect of reciprocating and unidirectional sliding motion on the friction and wear of copper on steel

From the practical necessity to obtain the friction and wear characteristics of materials used in machinery, various types of wear-testing machines have been developed and used. To obtain useful data for practical application, it is desirable that the investigation is carried out by a full-scale wear-testing apparatus having approximately similar contact conditions. Generally speaking, the obtained wear characteristics are different for every wear-testing apparatus used. When the type of wear-testing machine is not suitable, one cannot obtain the required wear characteristics. There are various parameters in wear-testing machines, such as configuration of contact surface and form of the relative motion between the test specimens. Thus, in this report, the effect of relative motion between contacting pair and friction process on obtained test results is investigated, for the combination of a copper pin specimen and a flat steel specimen. The microscopic structure of the pin specimen may be varied due to the friction and wear process. An optical microscope is used for the observations. The pin specimen is made from pure copper, which can be deformed easily.