Effects of Moisture Behavior on Corrosion Stiction in Friction Materials

This study investigates the correlation between moisture behavior and corrosion stiction mechanisms in NAO friction materials. While previous studies on corrosion stiction have primarily focused on electrochemical approaches, this study aims to elucidate the mechanism by examining moisture behavior within the friction material. Although recent research has investigated changes in pad properties in humid environments, most studies have primarily focused on variations in pad stiffness and the friction coefficient. To date, no studies have investigated the behavior of moisture within pads using Fick’s Second Law and its impact on corrosion stiction. In this study, Fick’s Second Law was applied to model moisture behavior in friction materials. The diffusion coefficient and maximum moisture content were quantified, revealing that moisture behavior in the friction material can be divided into two distinct stages: one following Fick’s Second Law and the other not. For NAO friction materials, experimental results indicate that a higher diffusion coefficient and lower maximum moisture content - leading to faster surface saturation- exacerbate corrosion and increase the risk of corrosion stiction. These findings highlight the importance of managing moisture behavior in friction materials to mitigate stiction-related issues. Further research is needed to examine the impact of lubricating films formed after burnishing friction material.