Friction on ice: stick and slip.

Faraday made investigations into behaviour of ice and snow. He was ahead of his time. Our paper briefly describes the current state of knowledge in ice friction and adhesion and its historical development. Important aspects of these phenomena in engineering, winter sports and the natural environment are considered. We report new results for static and dynamic friction of a metal (steel) and a polymer (PMMA) on ice over a range of temperatures (-3 to -13 degrees C), and interpret the behaviour by considering processes that operate at the interface and in the bulk of the materials. Clearly the chemical and thermomechanical properties of steel, PMMA and ice differ. The thermomechanical properties of ice itself also vary within the temperature range examined. We find higher static friction with increasing time, and a curious difference in the behaviour of the metal and polymer with temperature. We explain the results by considering the materials' stiffness, plastic deformation and creep, the ductile/brittle transition in ice, thermal properties, physicochemical properties of the surfaces and the real area of contact.