The development of wear-resistant composite coatings onto LLDPE substrate for tribological purposes

In this work, the wear resistance of the linear low-density polyethylene polymer (LLDPE) is enhanced by incorporating copper (Cu) and bronze powders into thin composite coatings. These coatings are applied separately to the LLDPE substrate using an ecologically friendly elaboration methodology. Digital image processing methodology indicates better homogeneity of LLDPE/Cu coatings when compared to the LLDPE/bronze coatings. Mechanical characterizations of the coating film show a significant increase in the tensile elastic modulus, tensile yield strength, and Vickers microhardness as the filler content increases. Reciprocating friction tests against high-chromium steel ball indicate that the friction coefficient of LLDPE/Cu composite coatings (with a 20% weight fraction) decreases by 24% compared to pure LLDPE, providing the best friction results. Bronze coatings show superior wear resistance with an optimum filler reinforcement equal to 10 wt%. An increase in the friction and wear performances of LLDPE/Cu coatings is associated with the ability of copper atoms in enhancing the adhesion of the transfer film to the steel counterface, preventing its direct contact with the coating. The transfer film is less coherent than that obtained with LLDPE/Cu coatings due to the spherical shape of bronze particles, which could act as bearing and roll inside the wear track.