1. Different types of wear that can affect engines

The metal surfaces of motors, subjected to solid or fluid friction, in the presence or absence of lubricant, can be affected by forms of wear ranging from gentle, regular and controllable wear (normal wear) to sudden deterioration leading to the motor being taken out of service.

The deterioration of motor surfaces is due to isolated or simultaneous phenomena that can be classified into four basic forms: adhesive, abrasive, corrosive and fatigue, to which can be added more complex forms of wear such as fretting corrosion, cavitation erosion and electrical wear. Some of these fundamental forms of wear are also involved as component phenomena. These different types of wear are summarized in the table at 1 and described in the documents cited at [1]