Regresar

Improve on corrosion resistant surface for AISI 4140 steel coated with VN and HfN single layer films

Abstract:

To improve the corrosion resistance of different industrials application, we studied vanadium nitride (VN) and hafnium nitride (HfN) single layer thin film, which were deposited onto Si (100) and AISI 4140 steel substrates via r.f. magnetron sputtering technique in Ar/N2 atmosphere with purity at 99.99% for both V and Hf metallic targets. Both films were approximately 1.2 ± 0.1 μm thick. The crystallography structures that were evaluated via X-ray diffraction analysis (XRD) showed preferential orientations in the Bragg planes VN (200) and HfN (111). The chemical compositions for both films were characterized by EDX. Atomic Force Microscopy (AFM) was used to study the morphology; the results reveal grain sizes of 78 ± 2 nm for VN and 58 ± 2 nm for HfN and roughness values of 4.2 ± 0.1 nm for VN and 1.5 ± 0.1 nm for HfN films. The electrochemical performance in VN and HfN films deposited onto steel 4140 were studied by Tafel polarization curves and impedance spectroscopy methods (EIS) under contact with sodium chloride at 3.5 wt.% solution, therefore, it was found that the corrosion rate decreased about 95% in VN and 99% for HfN films in relation to uncoated 4140 steel, thus demonstrating, the protecting effect of VN and HfN films under a corrosive environment. © 2013 by ESG.