Advancements in Polymer Friction and Wear: A Scratch-Modeling Approach

Abstract

Due to its many applications, including assessing strength, fracture toughness, and so on, the scratch method has attracted much attention in the research community. Finding the tribological characteristics of polymers, such as friction and wear, proved difficult for scratch approaches. This study tested a constant loading scratch method with a Rockwell indenter on the polymeric surface to develop an accessible wear and friction calculation model. Scratch load, speed, and passes, three primary factors, are considered to observe the polymers' response, particularly in terms of width, penetration depth, residual depth, and percentage of recovery. Considering all these scratch parameters, the experiments were conducted on five polymers: polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), polypropylene (PP), high-density polyethylene (HDPE), and polymethylmethacrylate (PMMA). The scratch characteristics are considered to calculate the friction coefficient and wear throughout the scratching process. Increased groove width, penetration depth, and residual depth and a decrease in recovery percentage are the effects of the number of scratch passes. The strain hardening caused by the multiple movements of the indenter on the same grooves causes a behavior change. With an increase in the scratch pass, the coefficient of friction decreases and stabilizes, and the volumetric wear increases, suggesting that more scratch passes will cause more material loss. This study derived two distinct models by applying the least-square curve fitting technique to evaluate friction and material wear characteristics. This model demonstrates a high degree of compatibility with the specific characteristics of polymeric materials and exhibits a significantly low margin of error.