Tribological behaviour of fluorinated and polyimide resins sliding against a metallic surface in liquid nitrogen

In a cryogenic fluid, the sliding of polymers over a metallic surface is governed by adhesion more than by deformation phenomena. Polyimide resins and fluorinated resins submerged into a cryogenic fluid exhibit a noticeable increase of hardness which induces a decrease of the friction coefficient and of the wear rate compared to a sliding process performed in ambient air. The decrease of wear and friction coefficient is linked to adhesive and deformation phenomena. For fluorinated resins a cold flow is observed. This behavior is illustrated and quantified from test results. Polychlorotrifluorethylene and polyimide resins are characterized.