Structure and performance of plasma-sprayed TiC/NiCrMo coatings prepared by different types of spraying gun

TiC/NiCrMo coatings were prepared on the substrate of Q235 steel (low carbon steel)by using two types of SG-100 plasma spraying gun labeled by Subsonic and Mach I.Morphology and phase composition of coatings were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) utilising back scattered imaging mode (BSE)and electron probe micro-analysis(EPMA).Wear tests were performed by using a ring-on-block tester under dry sliding condition.Results show that the coating prepared by Mach I gun banded well to the substrate and no delamination appears, while detachment between coating and substrate could be observed in the coating prepared by Subsonic gun.Meanwhile, large pores can be observed in the Subsonic gun-produced coatings. The Mach I gun-produced coating shows superior wear resistance to that of the Subsonic gun-produced coating.Partial oxidation of TiC and reaction between TiC and Mo occurred in both coatings.