Tribological behavior of polyamide-6 plastics and their potential use in industrial applications

The present research article addresses an investigation of tribological properties of 3 commercially available cast polyamide 6 (PA 6): a natural PA 6 polymer, a PA 6 filled with molybdenum disulfide (MoS2), and a PA 6 filled with a special solid lubricant. In order to analyze the potential use of these materials in industrial applications, their tribological results were compared with those measured for a commercial bronze alloy. All materials (including the bronze alloy) were subjected to sliding against a steel SAE 1020 disc in a tribometer. Three different types of tribotests were carried in this study: (i) wear tests, (ii) PV (pressure × velocity) tests, and (iii) stick-slip tests. Optical microscopy was employed to characterize the wear mechanisms of the materials selected in this study. PA 6 filled with special solid lubricant revealed superior tribological properties among the plastics, since it has shown the lowest coefficient of friction (COF), and the highest wear resistance and PV limit. PA 6 filled with the special solid lubricant also exhibited lower stick-slip oscillations than the PA 6 filled with MoS2. Micrograph analysis revealed abrasion as the most important wear mechanism for the PA 6 filled with the special solid lubricant. On the other hand, severe damage was observed on the surface of the natural PA 6 and the PA 6 filled with MoS2 in the wear tests. Bronze alloy exhibited the highest wear rate among the materials studied in this work. Adhesion was the dominant wear mechanism for this metal.