New approaches to improve the efficiency of the Laser-Arc technology for the deposition of ta-C coatings on an industrial scale

Downsizing of combustion engines is an appropriate solution to increase their efficiency. Unavoidably this leads to higher mechanical loads in the components of the powertrain. In order to withstand this stress super-hard carbon coatings (ta-C) are increasingly used, due to their extraordinary tribological performance.

Lately the laser controlled pulsed vacuum arc (Laser-Arc technology) has been established as one of the most effective techniques for the deposition of ta-C on an industrial scale. The Laser-Arc process allows for the deposition of good adherent films with thicknesses of up to 20 microns. Nevertheless a further increase of productivity is needed in order to achieve a higher market penetration of ta-C coatings for industrial applications.

In this work we present a new set-up which allows for the increase of the productivity of the Laser-Arc technology without additional power of the power supplies. In our approach we improve the focusing of the plasma. This leads to a significant increase in deposition rate due to an improved plasma transport. We found that at the same time the homogeneity of the coating thickness declined. To compensate for this effect we introduced a new construction, which allows to steer the plasma expansion without the use of magnets.