An ultra-thin water film plays the decisive role in steelââ?¬â??ice friction in bobsleighing.\nThe water film has a thickness on the order of nanometers and results from the superposition of an\nexisting quasi-liquid layer and additional surface water generated by frictional heat. When friction is\nmeasured as function of sliding velocity, the coefficients decrease according to the typical Stribeck\nbehavior. However, for highest sliding velocities, it is still unknown whether friction decreases\nfurther or shows an increase due to viscous drag. Both tendencies are essential for the construction of\nsafe bobsleighs and bobsleigh tracks. This contribution presents results of high-speed experiments\nup to 240 km/h for a steel slider on a disk of ice at different ice temperatures. In addition, using\nthe friction model of Makkonen, friction coefficients were calculated as function of sliding velocity\nand ice temperature. The significant correlation between experimental results and model calculation\nsupports the model conception of frictional melting and viscous shearing.
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