Tribological Study of Polymer-Metal Composite Coatings Deposited onto Organic Substrates

An experimental protocol has been established to elaborate composite coatings based on a matrix of linear low-density polyethylene (LLDPE)/ micrometric sized copper powder (Cu) deposited on a LLDPE substrate. The development of such deposits was possible by using thermocompression molding process preceded by a phase of dry mechanical mixing of the two powders constituting the coating. Four coatings were considered with 2 wt% Cu, 6 wt% Cu, 10 wt% Cu and 20 wt% Cu. The friction tests were carried out on an alternating tribometer with a sphere-on-plane configuration, the antagonist being a 100Cr6 ball. All tests were performed under the same conditions and stopped after 1,000 and 10,000 cycles of sliding. The cross-sectional profiles of the worn surfaces were recorded, and the wear volume loss were quantified. An optical microscope was used to observe the wear tracks. The observations showed a modification of the wear process from severe adhesive mechanism with the neat LLDPE to a mild abrasive mechanism with the 20 wt% Cu composite coatings after 10,000 sliding cycles. The friction coefficients and the wear volume loss decreased with increasing Cu weight fraction. Overall, it was demonstrated that copper particles can improve the tribological characteristics of LLDPE when added in concentrations ranging from 2%wt to 20%wt.