In situ observation of original wear process: deformation of surface crystal grains and origin of elemental wear debris in pure iron

摘要

The plastic deformation in the surface crystal grains that occurs when solid body surfaces contact and rub, and furthermore, the process of the earliest period (original process) in which wear starts to occur was observed in-situ using a friction surface microscope. The process which generates the elements of wear debris from the development of a slip system inside the surface crystal grains, and the fracture of crystal grains, and were shown and the following was clarified. In the surface crystal grains, compression stress due to the resultant force of the load and the friction force produced on the front of the contact point causes a slip to be generated in its maximum shear stress direction, and it develops following the crystal grain boundary along with the changes of the acting direction of the stress. After that, the perpendicular stress due to the load causes a new slip in the direction of the maximum shear stress, and these multiple slip systems exists in a criss-crossing manner. And, the fact that the developed depth of the slip systems, when a certain number of repetitions is exceeded, becomes virtually uniform from the surface was obtained. The mechanism by which the minute regions surrounded by slip lines fracture and the elements of wear debris are generated, when opposing surfaces adhere in the part in which the slip lines, in the surface part of the surface crystal grains that deform, are mixed, was clarified. And the elements of wear debris that had not been grasped up to now in the original process of wear were actually observed, and the fact that their size is 0.2～1.0μm was clearly established.