The effect of N+ ion-implantation on the corrosion resistance of HiPIMS-TiN coatings sealed by ALD-layers

Abstract

Plasma immersion ion implantation (PIII) was studied as a pretreatment method for improving the surface activity of TiN coatings deposited by high power impulse magnetron sputtering (HiPIMS) before being sealed with an ALD (Atomic layer deposition)-Al2O3 hybrid coating. The effect of different implantation energy and dose of nitrogen plasma on the microstructure and surface morphology of TiN coatings were investigated, and the surface morphology and fracture cross-section images of TiN/Al2O3 hybrid coatings with and without PIII pretreatment were compared. The corrosion protection properties were explored with linear sweep voltammetry in 3.5% NaCl solution at the room temperature. The results indicated that the N+ pre-ion-implantation had a significant influence on the microstructure and surface morphology of TiN coatings. With the increase of ion implantation energy and dose, TiN coatings gradually alter from the preferred orientation (200) to a mixture of (200) and (111), accompanied by the decrease of grain size on the surface. Moreover, the PIII pretreatment of the TiN coatings could significantly shorten the incubation time of the nucleation of ALD films, leading to a denser but thinner (at the same deposition cycles) layer of Al2O3, which plays a positive role in corrosion resistance. The coverage of ALD-Al2O3 films was improved with the increase of the nitrogen ion implantation energy and dose, resulting in better corrosion protection.