Abstract
The present work aimed at demonstrating the effectiveness of graphite containing plasma sprayed coatings to reduce friction coefficient in dry or starving lubrication conditions. Operative, environmental and economic considerations were important driving factors. Graphite particles were mechanical mixed with a cermet powder containing a fine dispersion of chromium carbide particles in a nickel-chrome metallic matrix. The coatings material was deposited by Atmospheric Plasma Spray onto steel substrates. The microstructure of the obtained coating was characterised by XRD and SEM/EDS. A strip draw apparatus, simulating the stamping process of steel sheets, was used to test the coatings. Several operative conditions were reproduced, by modifying the load and the amount of lubricant used. For comparison, uncoated samples were tested in the same conditions. The comparison of the results of strip draw tests carried out on coated and uncoated samples, shown that the use of graphite based self-lubricant coatings, deposited by plasma spray, allowed to decrease drastically the amount of lubricant.
