| There has been a great interest recently in the deposition of hard coatings on tools by physical vapor deposition processes. In this study (Ti, Al)N films were deposited onto high speed steels by biased activated reactive evaporation, varying plasma conditions during deposition. Electron density and electron temperature of glow discharge plasma during deposition were measured using a single electric probe technique. Discharge current of auxiliary electrode was a key parameter to control the plasma density. The films were characterized by x-ray diffractometry in order to determine phase, preferred orientation, mean microstrain, lattice parameter, and grain size. The film morphology was observed by scanning electron microscopy. Microhardness and adhesion strength were also measured. Electron density increased with discharge current of auxiliary electrode and average electron energy showed little variation. As the substrate bias voltage increased (200) texture developed and grain size decreased, while mean microstrain decreased and lattice parameter increased, all showing minimum or maximum values at-1000V bias. Microhardness increased with and adhesion was improved by substrate biasing. Also impact indentation modes showed the same tendency. All results would be caused by ion bombardment effects during deposition. |
|
