Structure and friction-reducing property of the sulfide layer produced by ion sulfuration

Sulfide lavers with a certain thickness were made on the surface of 1045 an d 52100 steels by means of the low-temperature ion sulfuration technique. M etallography, scanning electron microscope (SEM) + energy-dispersive x-ray analysis (EDX), and x-ray diffraction (XRD) were adopted to analyze the str ucture of sulfide layers; the tribological properties of the layers lubrica ted by paraffin oil were also investigated on a reciprocating tester. The r esults showed that sulfide layer is porous, and its structure is mainly com posed of FeS, FeS2, and substrate phases. The sulfide layer possessed a rem arkable friction-reducing effect; its friction coefficient was lower on ave rage, by about 50%, than that of the surface without layer. With the increa se of layer thickness, its friction coefficient was unchanged, and under lo w load conditions, its operational period was prolonged. Under the same exp erimental conditions, the operational period of sulfide layer on 52100 stee l was longer than that on 1045 steel, and its friction coefficient was lowe r as well.