Structural and Tribological Properties of Chromium Nitride - CrN_x Films on H-13 Tool Steels Produced by DC-Reactive Magnetron Sputtering

摘要

Chromium nitride thin films have been deposited on H-13 tool steel substrates by DC-Reactive magnetron sputtering. The influence of process parameters (mainly the Ar/N_2 ratio) on film properties has been investigated. The characterization of the coatings was performed by X-ray diffraction (XRD), Raman Spectroscopy (RS), nano-indentation and pin-on disk experiments. This study allows us to analyze the influence of the change of N_2 flow rate in crystal phases, crystal orientation/texture and crystallite size. XRD reveals that an increase of N_2 flow in the working atmosphere produces changes from a hexagonal Cr_2N to cubic CrN microstructure with strong (111) orientation. These polymorphic changes are also corroborated through RS spectra obtained. The strain in CrN_x crystals increases with nitrogen content (Cr/N ratio varied from 0.52 to 0.89), which means that high stresses are present. The hardness and Young's modulus of films with dominant CrN phase increases with the increase of nitrogen flow during deposition. Wear test showed an increase in wear resistance up to 44% for films with highest N_2 concentration, as compared with uncoated H-13 samples.