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.

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The potential of applying thermodynamics to study the tribological response of a tribological system is addressed in this paper. In order to do so, a model was developed to obtain the entropy flow generated by three different dissipative processes present in dry sliding, namely, thermal gradient, heat conduction, and abrasion. The flash and bulk temperatures at the contact interface were obtained with the aid of the finite element method (FEM), and pin-on-disk tests were performed by using titanium alloy (Ti6Al4V) disks and tungsten carbide (WC/10Co) pins. Then, the wear rate obtained from the tribological tests was correlated with the calculated entropy flow, and a degradation coefficient was associated to the sliding process. A linear dependence of the wear rate and the degradation coefficient was observed regardless of the variation of the points of operation of the system, so it is proposed that the coefficient of degradation used is inherent to the tribological system.