Dual-functional thermal management of railway rails using ultrathin Ag thin-film heaters

초록

Seasonal temperature extremes pose serious safety challenges to railway rails, including excessive heat accumulation under solar irradiation in summer and ice-and snow-induced loss of wheel-rail adhesion in winter. Here, we propose an ultrathin silver (Ag) thin-film-based solution as a dual-functional thermal management strategy for railway rails, providing both heat shielding and active de-icing within a single, non-detachable system. Ag films with thicknesses of 10-35 nm were deposited on polyimide (PI) substrates by electron-beam evaporation and investigated in terms of structure, electrical conductivity, and thermal performance. The Ag/ PI structures effectively suppressed radiative heat transfer under simulated solar irradiation, mitigating rail temperature rise in summer conditions. In addition, the ultrathin Ag films functioned as efficient Joule heaters, reaching approximately 90% of the steady-state temperature within 10 s and maintaining stable heating performance under sub-zero conditions below-20 degrees C, enabling effective de-icing. Rail-scale experiments further demonstrated practical applicability, where heaters mounted on the rail web surfaces induced uniform temperature elevation at the rail top surface via thermal conduction, raising it above the freezing point even under sub-zero ambient conditions. These results demonstrate that ultrathin Ag thin-film heaters provide an effective and integrated approach for year-round thermal management of railway rails, contributing to enhanced operational safety under diverse climatic conditions.

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