The quality of PVD coatings is determined by its adhesion to the substrate. State-of-the-art techniques for substrate pre-treatment for adhesion improvement are glow discharges. However, this method cannot be applied for temperature sensitive and electrically non conductive substrates. In contrast to glow discharges, ion sources produce a plasma and accelerate ions with electrostatic or electromagnetic forces. In the scientific field, mainly gridded ion sources are applied, which have a high degree of complexity and require substantial maintenance to operate due to the limited lifetime of grids and the electron source. Thus, they are scarcely applicable for industrial processes. As an alternative, gridless ion sources offer an elegant solution to ion beam production.

One type of gridless ion source is the so-called anode layer source (ALS) which was used in this work for pre-treatment of different types of steel prior PVD coating at room temperature. The effect of the plasma treatment was investigated by contact angle measurements and microscopic investigations of the substrate surfaces. The adhesion of sputtered TiN coatings was measured by scratch test, the residual stress of the coatings was determined by XRD. The highest increase of the film adhesion was observed for hard substrates. Best results were found for medium ion energies of approximately 1000 eV. The most significant effects are occurring during the first 5 minutes of pre-treatment. The increase of the film adhesion correlates with a decrease of the residual stresses in the films. High ion energies cause a change of the surface topography of the substrate and lead to reduced film adhesion.