Tribological behaviour of HVOF-sprayed Ni-based self-lubricating composite coatings

ABSTRACT In the current investigation, the tribological behaviour of HVOF sprayed Ni-based self-lubricating composite coatings on cast iron substrate, which is a commonly used material for cylinders, was studied. Four different combinations of coatings materials, namely, Ni–10Mo–10Al, Ni–10Mo–10Al–10graphite, Ni–10MoS2–10Al and Ni–10MoS2–10Al–10graphite were deposited on a cast iron substrate. Then, the mechanical, morphological and tribological properties of the coated and uncoated samples were analysed by performing microhardness measurements, a scratch resistance test, a wear test (pin on disc), XRD and SEM/EDS. Results showed that among all coatings, Ni–10MoS2–10Al–10graphite coated cast iron sample has the highest microhardness of about 349.4 HV 111% higher than the substrate material and lowest average wear rate of about 1.1 × 10−4 g s−1.