The influence of iron oxides on wheel–rail contact: A literature review

Abstract

In contrast to other third-body layers – such as water, oil, sand, and leaves – iron oxides exert a constant influence on the friction and wear of wheel–rail contact. However, studies that focus on the influence of iron oxides have not been conducted systematically until the 21st century. This study is a comprehensive presentation of early and recent research works related to the influence of iron oxides on the wheel–rail contact. The characteristics of iron oxides in general and those between railway wheels and rails are discussed. A comparison of various laboratory tests and their relation to actual conditions is also presented. The authors find that the influence of various types of iron oxides on friction and adhesion differs. The thickness of the iron oxide layer also affects the friction and wear. However, the results obtained from laboratory rigs differ from those obtained in field testing. Therefore, it is critical to formulate a standard procedure that produces iron oxides that are similar to those observed in the field. Compared to the case of wheel–rail friction and adhesion, the influence of iron oxides on wear is not so well investigated. Thus, further research in those areas is warranted.