Friction and Wear Behavior of Laser-Induced Graphene Structures on Polyimide Films.

Laser-induced graphene (LIG) is formed by the conversion of certain carbon precursors when irradiated with a laser beam. Predesigned LIG patterns are scribed onto the precursor material in a low-cost and maskless process, which enables the fabrication of flexible and electrically conductive materials for various applications. This study explores the friction and wear behavior of LIG from a polyimide precursor. Line patterns with different widths (200, 100, 50, and 30 μm) are introduced to modify the friction properties. An ultraviolet laser source with a nominal beam size of 2 μm is used, as it allows to scribe patterns with smaller dimensions and at higher resolution compared to the more commonly applied infrared laser sources. A distinct correlation is established between the pattern and its friction behavior, where lowering the line size results in a decrease in the coefficient of friction (COF). The wear behavior is evaluated, revealing gradual wear of the protruding LIG roughness peaks and a change in the graphenic material, which reduces the COF during the running-in stage of the tribological testing. Due to its versatility in terms of precursor material, patterning options, and morphology modification, LIG represents a meaningful candidate for customized tribological applications.