DIRECT OBSERVATIONS OF FRETTING WEAR OF STEEL

An investigation was performed to study the factors affecting the tran sition between fretting and reciprocating sliding wear using a new tec hnique in which a transparent (sapphire) disc is rubbed against a stee l sphere under both lubricated (hexadecane) and dry conditions. The te chnique allows direct observation of the wear occurring in the contact as well as the appearance, size and transport of the wear debris. The wear behaviour was qualitatively similar to that occurring between st eel-on-steel surfaces. Increasing the stroke length led to much more r apid removal of debris from the contact, together with accompanying ch anges in size and composition. In general, the results lend support to the contention that the transition to reciprocating sliding behaviour is controlled by the instantaneous quantity of debris remaining withi n the contact. (C) 1997 Elsevier Science S.A.