Macroparticles formation in cathodic arc deposition of nitride coatings from TiNb alloy cathodes

Abstract

Reduction of macroparticles embedded within the cathodic arc deposited coatings is important for achieving high quality coatings with superior tribological properties, and it remains a major challenge in cathodic arc depositions. In the present study, the authors aim to understand the nature of macroparticles formed from TiNb alloy cathodes and the role of TiNb cathode nitridation in reducing the amount of generated macroparticles. The microstructure of the macroparticles was investigated using scanning transmission electron microscopy-energy dispersive spectroscopy, scanning electron microscopy, and x-ray diffraction techniques and revealed compositionally different macroparticles, such as macroparticles with a Nb-rich core, Ti-rich macroparticles, and macroparticles with a composition similar to that of the coatings. The examination of the macroparticles indicated the compositional segregation of niobium and titanium. With increasing N2 gas pressure during deposition, the macroparticles showed increased nitridation while the density of macroparticles within the coating was slightly diminished.