The friction of ice on ice at low sliding velocities

Abstract

The kinetic coe cient of friction · has been measured for both freshwater, granular ice and saltwater, columnar ice sliding against itself. The variables were ambient temperature (¡38C to ¡408C), sliding velocity …5 £ 10 ¡7 ± 5 £ 10 ¡2 m s ¡1 †;normal pressure (0.007± 1.0 MPa) and grain size (2.5± 6.0 mm). Generally, · decreased with increasing velocity and with increasing temperature, but was relatively insensitive to both pressure and grain size over the ranges investigated. At the lower temperatures (¡308C and ¡408C) the friction± velocity curve exhibited a peak at intermediate velocities. The friction coe cients for freshwater and saltwater ice were almost indistinguishable at higher temperatures (¡38C and ¡108C), but saline ice had lower friction at lower temperatures. The results are explained in terms of frictional heating, creep and fracture.