%0 Journal Article
%A Domínguez-Meister, S.
%A El Mrabet, S.
%A Escobar-Galindo, R.
%A Mariscal, A.
%A Jiménez De Haro, M. C.
%A Justo, A.
%A Brizuela, M.
%A Rojas, T. C.
%A Sánchez-López, J. C.
%T Role of y in the oxidation resistance of CrAlYN coatings
%D 2015
%@ 0169-4332
%X CrAlYN coatings with different aluminum (4-12 at.%) and yttrium (2-5 at.%) contents are deposited by d.c. reactive magnetron sputtering on silicon and M2 steel substrates using metallic targets and Ar/N 2 mixtures. The influence of the nanostructure and chemical elemental distribution on the oxidation resistance after heating in air at 1000 °C is studied by means of cross-sectional scanning electron microscopy (X-SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GD-OES). The sequential exposure to the metallic targets during the synthesis leads to a multilayer structure where concentration of metallic elements (Cr, Al and Y) is changing periodically. A good oxidation resistance is observed when Al- and Y-rich regions are separated by well-defined CrN layers, maintaining crystalline coherence along the columnar structure. This protective behavior is independent of the type of substrate and corresponds to the formation of a thin mixed (Al, Cr)-oxide scale that protects the film underneath. The GD-OES and XRD analysis have demonstrated that Y acts as a reactive element, blocking the Fe and C atoms diffusion from the steel and favoring higher Al/Cr ratio in the passivation layer after heating. The coating with Y content around 4 at.% exhibited the best performance with a thinner oxide scale, a delay in the CrN decomposition and transformation to Cr 2 N, and a more effective Fe and C blocking.
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