DLC and metallic nanometer multilayers deposited by laser-arc

The method of laser-induced vacuum arc (laser-arc) combines the good controllability of pulsed laser deposition with the high efficiency of a vacuum arc technique. One advantage of this technique is the essential reduction of droplets allowing the deposition of high-quality amorphous carbon films. These hydrogen-free films with very high hardness up to the superhard range exhibit excellent wear resistance and low friction. In the present paper, another advantage of the laser-arc is demonstrated, i.e. the possibility of depositing multilayer coatings down to the nanometer level of each individual layer thickness with high efficiency and high accuracy. These possibilities open new ways to overcome the principal problem of hard PVD coatings, i.e. the high internal stress which restricts the film thickness. Multilayer systems of Al-C and Ti-C with systematic variations of single layer thickness and thickness relationship were analysed by electron microscopy and Auger electron spectroscopy. The Young's moduli were measured by the non-destructive ultrasonic surface wave method (US-SAW). The alternating hard and ductile layers allowed a remarkable relaxation of the internal stresses. Furthermore, the growth of the particle induced defects (droplets) could be strongly reduced.