In-situ Observation and Study of the Unlubricated Wear Process

Wear characteristics and changes on wear surface under the condition of dry friction were observed by a scanning electron microscope and a new experimental apparatus which was used to directly observe the dynamic wear process.The wear surface can be divided into a real contact area and a transition wear area. The wear mechanisms in the two areas were different. Adhesion wear occurred in the real contact area. There is a trend that the size of wear particles increased obviously along the direction of friction force. Along with progressing of wear in the real contact area, the transition area could be gradually changed into the real area, mean while, the unworn area could be changed into the transition one because of the increase of particle number. The results of the changes in friction force measured during wear process shown that the adhesion force is extremely close to the theoriticai value according to Bowden and Tabor's work.