The effect of transport ratio and ion energy on the mechanical properties of IBAD niobium nitride coatings

Niobium nitride films were produced by ion beam assisted deposition (IBAD) using low (90 eV) and moderate (750–800 eV) energy nitrogen ion beams and electron-beam evaporated niobium. The transport ratios (ion to atom arrival ratios) used were approximately 0.062, 0.125, 0.25, 0.33, 0.50, 0.75 and 1.0. The resulting microstructure, crystal phase, and composition of the films were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Rutherford backscattering spectrometry (RBS). The hardness, coefficient of friction, and wear resistance were assessed. The research detailed herein describes relationships between IBAD process parameters, NbN film structure and phase, and the mechanical properties of the films.