Characteristics of particles generated at the interface between sliding steel surfaces

This paper is an attempt to further clarify and classify the range of wear modes which can occur at the interface between steel surfaces subjected to sliding motion, a variety of speeds and loads, with and without lubrication. Previous researchers have been able, from examination of the wearing surfaces, to identify a number of distinct wear modes and to classify them according to operating conditions. The present paper shows that it is possible to arrive at a comparable classification of wear modes based on examination of the wear debris rather than the worn surfaces. Consequently, it is possible to determine the wear modes in a machine from observation of the debris in the lubricant without requiring access to the wear surfaces themselves.The wear particles were generated by rotating a cylindrical sleeve of AISI 52100 steel in contact with three types of fixed wearing surfaces, crossed AISI 52100 steel cylinders, fixed spherical balls of AISI 52100 and AISI 1018 steel and a flat plate of AISI 1018 steel. Surface speeds ranged from 0.19 to 5.0 m/s and the load from 1 to 80 kg. These particles were collected and examined in both an optical and a scanning electron microscope. X-ray diffraction studies of selected particle types were also made.These studies revealed six different wear regimes which depended on the test parameters. Each regime produced wear particles of characteristic morphology and composition. All of the types of particles studied here have been found in the lubricating oil of field operating machines.