Formation of macroparticles in are ion-plated nitride coatings

Abstract

On the basis of transmission electron microscope analysis, a model describing the formation of macroparticles in are ion-plated nitride coatings is proposed. While emitting from the cathode, the metal droplets react with nitrogen during their travel to the substrate and form a thin layer of nitrides on the surface of the droplets, resulting in a core-shell structure. The flattened torus voids are gradually produced beneath each droplet upon impact on the substrate, which causes shadowing of the ion flute during deposition. Subsequent growth of the nitride coating on the droplets follows the orientation of the nitride nuclei in the outer shell to form a radial type of structure, until coalescence with the regular nitride columns growing perpendicular to the substrate surface occurs. (C) 2001 American Vacunm Society.