Lubrication wear mechanism of sliding bearing material WJ2 in the contaminated oil

Abstract

Previous studies investigated the wear mechanisms under dry sliding conditions and in new oil. However, in practice, wear particles and dust are introduced into the lubricating oil of the machinery. Therefore, it is difficult to conclude that the wear mechanism of the machinery was accurately reproduced in those studies. In this study, we aimed to clarify the wear mechanism of a sliding bearing material, WJ2, under lubrication using seven types of oil contaminated with solid particles. Wear tests were conducted with the contaminated oil using a block-on-ring tribo-tester. The results showed that, even though the ISO cleanness codes were almost the same for all the oils, the wear mechanisms of WJ2 were different. There were three different action modes of iron particles. The gaps between the iron particles and the WJ2 matrix are formed when iron particles were buried into the surface of the WJ2 matrix. In the case of oil contaminated with a mixture of iron particles and soft particles, shear fracture occurred from the gaps formed by the buried iron particles and pits were formed. The sizes and depths of the pits varied with the mutual solubility between the mixed soft particles and the block material; with another type of metal with a low mutual solubility, the concavities were small and shallow. The wear mechanisms of WJ2 were clarified under lubrication with the contaminated oil.

Keywords

• wear test
• wear mechanism
• degradation
• contaminated oil
• electric contact resistance