Influence of different pulse parameters on the deposition of Al2O3

Oxide PVD-coatings like crystalline gamma-Al2O3 offer great potential for their use in cutting operations. They enable high resistance against abrasive wear, chemical inertness and high hot hardness. The pulsed Magnetron Sputter Ion Plating is a promising technique for applying oxide coatings onto cutting tools. The pulse duration and the duty cycle influence the stability of the deposition process. On the one hand pulse parameters can affect the ionization, on the other hand "target poisoning" and arcing can be reduced by choosing the right pulse values. In the present work the influence of different pulse parameters was investigated using optical emission spectroscopy (OES). It can be revealed that longer t(rev)-pulse times as well as lower duty cycles increase the aluminum ion density. With the chosen pulse parameters different coatings were deposited. The analysis was done using common thin film test equipment such as calo-test, nanoindentation or scratch test. The results show that an increasing pulse frequency decreases the hardness, but improves adhesion of the coating.