The selection of wear-resistant materials is usually based on long-time testing. A method of structural investigations of materials can be used for reducing the duration of such tests. This method is based on the results of the transmission electron microscopy and X-ray investigations of the surface layers. Results of these studies show that every material is characterized by a definite state of the surface layer structure, which corresponds to the conditions of friction. Under constant conditions of friction the characteristics of the structure change only during running-in period. Thereafter the structure of surface layer remains unchanged throughout the entire subsequent test period. Consequently, for determination of the structural characteristics that correspond to particular friction conditions, it is necessary to test the material only until the end of the running-in period. Specimens of different materials were investigated before and after testing in order to establish the relationship between the change of the structure of the surface layers of a metal under friction and the comparative wear resistance. These investigations showed that in the absence of phase transitions in the material under friction, the smaller the structural changes, the higher the wear resistance. This criterion can thus be used to reduce the duration of the testing period for wear resistance of materials under nominal friction conditions. It is thus possible to select materials with higher wear resistance for different parts of machines, such as trucks or looms. The results can be also applied in the development of a new wear-resistant materials for different friction conditions.
