After cold plasma treatment of poly(ethylene terephthalate) and poly(ether‐ether ketone) surfaces by dielectric barrier discharge (DBD) under atmospheric (air) conditions, variations in surface chemistry, and morphology were investigated in relation with adhesion and tribological properties. According to XPS measurements, surface oxidation caused the formation of low molecular weight moieties of carboxylic acids. The latter resulted in more hydrophilic surfaces according to water contact angle measurements, with mainly a higher polar surface energy component. In parallel, the surface roughness of originally polished surfaces reduced due to flattening of local surface asperities after DBD. The DBD significantly improved the adhesive shear strength for different glue types in polymer/polymer and polymer/steel joints, while the best adhesion was observed for a two‐component epoxy type adhesive. Under dry sliding conditions, the coefficients of friction were lower after DBD compared to pristine samples only under mild sliding conditions (v = 0.05 m/s; p < 1 MPa.m/s), while the higher normal loads caused an increase in coefficients of friction likely due to the higher contributions of surface deformation. Most interestingly, the lower coefficients of friction after DBD were observed under oil lubrication and after cleaning the sliding track (“run‐out” condition), due to the better retention of oil at the sliding surface for plasma‐treated polymers. POLYM. ENG. SCI., 58:E93–E103, 2018. © 2017 Society of Plastics Engineers

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This paper presents a new approach for modelling the wear in wheel-rail contacts for a wide range of test and contact conditions (material pairing, load, creep, lubrication etc.) in the mild and severe wear regimes with one set of model coefficients. The approach is based on a detailed analysis of 56 Twin-Disc experiments in combination with existing knowledge from the literature. The model considers the thickness of the damaged layer caused by severe plastic shear deformations in the near-surface layer of wheel or rail and the maximum shear stress in the contact as the main influencing factors responsible for the observed wear behaviour. In this way, a much better prediction quality can be reached for varying test and contact conditions compared to the state of the art energy dissipation or sliding based approaches. The model includes a low number of model coefficients which are independent of test and contact conditions.

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Polytetrafluoroethylene surface was treated by atmospheric DBD plasma for 1 min in ambient conditions. The effect of DBD plasma introduces signifi cant increasing of the surface energy (wettability) within 24 hours after treatment. However, the surface starts recovering to the original state with ageing. The surface elemental composition shows enhancing in oxygen content which suggests presenting the polar functional groups. The surface roughness exhibits a mild reduction within 24 hours after treatment. Whereas, the roughness values start to increase with the function of time.