Tribological study of W-S-(C) sputtered coatings sliding against aluminium at elevated temperatures

Abstract

Aluminium metal forming is often performed at elevated temperatures which can cause significant galling, damage to the produced parts and increased manufacturing costs. Self-lubricating thin films deposited by magnetron sputtering are good candidates for alleviating this issue. In this study we deposited three types of films containing transition metal dichalcogenides, of which one consisted only of WSx and two films were alloyed with carbon. The aim of the work was to assess the ability of these coatings to reduce galling in sliding contacts with aluminium at elevated temperatures. The thermal analysis indicated that the maximum operating temperature should be ~400–430 ◦C, for the pure WS coating, and a higher value of ~480–490 for the carbon alloyed films. The coatings managed to provide friction reduction in all the testing conditions, except for the carbon alloyed one with the highest amount of carbon which could not provide lubrication against aluminium at 400 ◦C.