Tribological behavior of polymeric 3D-printed surfaces with deterministic patterns inspired in snake skin morphology

Surface engineering can rely on biological systems to mimic characteristics of living specimens in order to develop and fabricate deterministic elements to modify friction. In this work, the tribological response of bio-inspired patterns obtained by 3D-printing for polymer-metal contact in dry conditions are discussed. The repetitive array of elements called 'fibrils' in the ventral scale of Phython regius snake was used as an inspiration to fabricate the deterministic surfaces. The texturized samples were 3D-printed with Nylon filament and the counterpart was AISI 304 stainless steel. The results showed that the friction coefficient was consistently lower in the tests carried out with the texturized samples in comparison to those performed with stochastic surfaces. Lower friction values were clearly correlated to geometrical descriptors of the texture patters including the Feature Slenderness Ratio (FSR) and the Feature Aspect Ratio (FAR). The analysis of polymer's worn surfaces revealed adhesive damage, localized melting and roll formation as the main wear mechanisms.