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The effect of the addition of nickel, titanium, and nitrogen on the air oxidation behavior of W‐based sputtered coatings in the temperature range 600 to 800°C was studied. In some cases these additions significantly improved the oxidation resistance of the tungsten coatings. As reported for bulk tungsten, all the coatings studied were oxidized by layers following a parabolic law. Besides WO3 and WOx phases detected in all the oxidized coatings, TiO2 and NiWO4 were also detected for W‐Ti and W‐Ni films, respectively. WOx was present as an inner protective compact layer covered by the porous WO3 oxide. The best oxidation resistance was found for W‐Ti and W‐N‐Ni coatings which also presented the highest activation energies ( Enormala=234 and 218 kJ mol−1 respectively, as opposed to Enormala≈188 kJ mol−1 for the other coatings). These lower oxidation weight gains were attributed to the greater difficulty of the inward diffusion of oxygen ions for W‐Ti films, owing to the formation of fine particles of TiO2 , and the formation of the external, more protective layer of NiWO4 for W‐N‐Ni coatings.

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