Rust + water droplets = low adhesion on the track
The research results of Yi Zhu, Ph..D Student in Tribology, shows that ordinary rust together with high levels of humidity and low temperature can reduce the friction significantly in the tiny contact zone between steel rail and steel railway wheel.
The results, that was recently published in the scientific journal Tribology Letters “Friction between wheel and rail: A pin-on-disc study of environmental conditions and iron oxides” November 2013, Volume 52, Issue 2, pp 327-339, has a fundamental impact on the future combating the low adhesion between railway wheel and rail.
This study has been collaboration between the division of System and Component Design (Yi Zhu and Ulf Olofsson) at KTH Machine Design and Railway Technical Research Institute in Japan (Hua Chen). In a recently published full scale test, together with Stockholm Public Transport (Rickard Nilsson), this laboratory study has been verified in a full scale test by identifying high concentration of iron oxides in the surface layer at low measurable friction levels.
This full scale test study was recently published in the scientific journal Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit “A field test study of leaf contamination on railhead surfaces” Volume 228, Issue 1, January 2014, Pages 71-84.