Microstructure and Tribological Properties of Self-Lubricating Graphite/Ni60 Composite Coatings Prepared by Laser Cladding

Abstract

Ni60 superhard alloy with the additions of graphite solid lubricants was successfully prepared on 45 carbon steel substrate by means of laser cladding. The quality of coating was relatively high and had metallurgical bonding with the substrate. The morphology of laser cladding layer was observed by SEM, composition analysis was applied by EDS. Elevated temperature frictional behaviors of graphite/Ni60 composites coatings were investigated on MMG-10 wear machine. The results showed that the friction coefficient of graphite/Ni60 composite coating was obviously decreased from 0.55 to 0.20 with increasing temperature. The wear mechanism transformed from adhesion to oxidation with the increase of temperature. The graphite/Ni60 composite coating material showed the optimum self-lubricating property at 500°C.

Mechanical and tribological performance of a hybrid MMC coating deposited on Al–17Si piston alloy by laser composite surfacing technique

“…In one study it was found that the wear rate was correlated with the concentration of graphite in the plasma sprayed metal matrix composite coating at a maximum of 8 wt% graphite. 19 The beneficial effects of graphite were also explored by Yang et al 20 where graphite was added in the Ni-60 super hard alloy to realize a significant improvement in friction coefficient from 0.55 to 0.20. Ying et al 21 fabricated Ni60/TiC/graphite coating for stainless steel specimen to witness a drop of friction coefficient from a range of 0.7–0.8 to that of 0.4–0.5.…”