Friction and wear behavior of titanium nitride, zirconium nitride and chromium nitride coatings at elevated temperatures

Friction and wear behavior of TiN, ZrN and CrN coatings in contact with Inconel (trademark of the International Nickel Co., Inc.) 718 were investigated using a ring-on-disc test machine at 500°C and 600°C. The applied load was 267 N and the linear velocity was 1.24 m s −1. The wear of the coatings was extremely small compared with that of Inconel 718, which was found to depend strongly on its mating coating. At 500°C, the wear performance of ZrN- and CrN-Inconel 718 wear couples were comparable to or better than an uncoated couple, respectively. At 600°C, the wear performance of CrN-Inconel 718 was markedly better than that of ZrN-Inconel 718. The microstructural and chemical characterization of wear surfaces and debris were investigated by scanning electron microscopy and energy dispersive spectrometry. X-ray diffraction revealed that the wear debris from all wear couples consisted of NiCr 2O 4, NiO, Cr 2O 3 and Inconel 718. Based on the morphology and chemistry changes of wear surfaces and phase compositions of wear debris, the adhesive and oxidative wear was the primary mechanism for the uncoated Inconel 718 wear couple. For the coating-Inconel 718 couples, the abrasive and oxidative wear accounted for material removal of the Inconel 718 disc; the adhesive wear and oxidative and chemical wear were responsible for the coating removal.