Novel performance in physical and corrosion resistance HfN/VN coating system

4140 steel substrates were coated with hafnium nitride/vanadium nitride multilayered with the objective of improving their corrosion resistance. The multilayered coatings were grown via a reactive r.f. magnetron sputtering technique by systematically varying the bilayer period (A) and the bilayer number (n) while maintaining constant the total coating thickness (similar to 12 mu m). The coatings were characterized by X-ray diffraction (XRD), electron and transmission microscopy. The electrochemical properties were studied by Electrochemical Impedance Spectroscopy and Tafel curves. XRD results showed preferential growth in the face-centered cubic (111) crystal structure for [HfN/VN](n) multilayered coatings. The best enhancement of the mechanical behavior was obtained when the bilayer period (Lambda) 15 nm (n=80) which yielded the highest hardness (37 GPa) and elastic modulus (351 GPa). The values for the hardness and elastic modulus are: 1.48 and 1.32 times greater than the coating with n=1, respectively. The maximum corrosion resistance was obtained for coatings with (Lambda) equal to 15 nm, corresponding to bilayer n=80. Polarization resistance and corrosion rate was around 112.19 k Omega cm(2) and 0.094*10(-3) mmy respectively, these values were 172.6 and 0.007 times better than those shown by the uncoated 4140 steel substrate (0.65 k Omega cm(2) and 0.014 many, respectively). (C) 2013 Elsevier B.V. All rights reserved.