Improvement of the magnetron sputtered coating adhesion through pulsed bombardment by high-energy ions

Comparative study of titanium nitride deposition has been carried out, the growing coating being uninterruptedly bombarded by 100-eV ions or ions accelerated by high-voltage pulses applied to the substrate. The study revealed that microhardness of coatings synthesized using 25-kV pulses rises from 21 GPa to 29 GPa when percentage of nitrogen in the mixture with argon increases from 15% to 20%. With a further increase of nitrogen percentage to 30%, the microhardness slightly diminishes to 27 GPa. In contrast to golden coatings synthesized at low-voltage substrate biasing, the color of titanium nitride coating produced using high-voltage pulses is brown. The most striking difference of coating deposited using high-voltage pulses applied to the substrate is its perfect adhesion despite the interface formation at the room temperature without any preheating and activation. The adhesion characterization using a scratch-tester has revealed that critical loads of coatings synthesized using 25-kV pulses are several times higher than those of conventional nitride coatings synthesized at uninterrupted substrate biasing of 100 V. When the pulse amplitude diminishes to 5 kV, the critical loads and microhardness of the coating decrease to conventional values.