Friction setup and real-time insights of the contact under controlled cold environment: The KŌRI tribometer for...

A friction setup combining real-time ice-rubber contact visualization, force measurement, and a compact controlled cold environment system was developed in order to investigate ice-rubber contact complex tribological response and the various contributions to friction, such as viscoelastic deformation, ice surface melting, adhesion, ice creep, or quasi-liquid layer effect. The cold system was based on a cryogenic bath circulator, an air convection circuit, and several thermal insulation combinations such as silica aerogel and expanded polystyrene. The KŌRI tribometer allows one to reach negative temperatures until -20 °C and to perform tribological experiments for velocity from 50 μm s^-1 to 1 m s^-1 under load up to 50 N and to simultaneously measure resultant forces until 30 N and visualize the contact in real-time. In parallel, an ice manufacturing unit and a specific protocol were developed to grow a transparent ice disc with a controlled initial roughness and surface state. Real-time and simultaneous visualization of the ice-rubber contact provides additional data, such as the apparent contact area and the mean size of a real contact spot during friction, after adequate and dedicated image processing. To illustrate the capability of the KŌRI tribometer, rubber-ice friction measurements were performed at -10 °C and the results are presented here, as a function of time and velocity.