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High power impulse magnetron sputtering (HIPIMS) has been used for the pretreatment of high speed steel (HSS) substrates. Subsequently, a CrN thin film was grown by direct current magnetron sputtering. The aim was to correlate the interfacial microstructure and chemistry as well as the induced stress of the film and the interface region to the adhesion of the film. The pretreatment was performed utilizing Cr ions in an inert gas atmosphere varying the negative substrate bias (Ub) between 0 and 1100 V at ambient and 400°C substrate temperatures. In situ stress measurements were performed to monitor the stress evolution during pretreatment as well as during film growth. X-ray diffraction and electron microscope techniques were employed to characterize the lattice structure, microstructure as well as the interface chemistry. The film adhesion was obtained using scratch test measurements. The study shows that a sputter cleaned substrate surface with well preserved crystal structure of the substrate enhances the adhesion of the coating by promotion of local epitaxial growth. Furthermore, after deposition the samples were annealed at 670°C in an Ar atmosphere and this also proved to have a large effect on the adhesion enhancement by allowing for interdiffusion in the interface region and due to promotion of interface strain relaxation. On the other hand, implantation of target material into the substrate had limited influence on the adhesion compared to the clean oxide free surfaces. The influence of radiation induced lattice defects and strain on the bonding strength at the interface are also discussed. |