MICROSTRUCTURES AND WEAR-RESISTANCE BEHAVIORS OF FERROUS SULFIDE COATINGS

Low temperature ion sulfuration and high velocity oxy-fuel (HVOF) sprayed processes were used to prepare the FeS solid lubrication coatings respectively. Their friction and wear behaviors were comparatively investigated on a MM-200 ring-on-block wear tester under dry condition and a QP-100 ball-on-disc wear tester using No.40 machine oil as lubricant. SEM equipped with EDX and XRD were employed to analyze the morphologies of the two kinds of FeS coatings, as well as their phase structures. The results show that the properties of friction-reduction, wear-resistance and anti-scuffing of two kinds of coatings are all superior to the same substrate. The friction-reduction and were-resistance of the ion sulfuration coating are better than those of the HVOF sprayed FeS coating, and the anti-scuffing of the sprayed FeS coating is better than that of the ion sulfuration coating. The difference of the tribological properties of two coatings can be attributed to their different forming mechanisms and coating structures. The ion sulfuration coating prepared in the vacuum furnace was formed through the diffusion and penetration of sulfurs into the substrate. The bond between coating and substrate is chemical bond. The coating is thin and successive. The sprayed FeS coating prepared in atmosphere was formed through the building up of FeS grains. It belongs to mechanical bond. The coating is thick and contains some impurities and pores.