## 2 Materials and Methods  
Tungsten nitride thin films were deposited by DC-pulsed reactive sputtering using a planar magnetron sputtering deposition apparatus from Material Research Corporation mod. MRC 643. Substrates, maintained at floating potential, were mounted on a holder that moved back and forth in relation to the tungsten target (12 cm \(\times\) 38 cm, 99.95 % of purity) with a sweep velocity of 200 cm/min and substrate-target distance of 80 mm. All samples were fabricated starting from a base vacuum condition of approximately 2 \(\times\) 10\({}^{-4}\) Pa. The films were produced in an argon/nitrogen atmosphere with 14% nitrogen concentration in the sputtering gas, at a total deposition pressure of 0.73 Pa and at three power densities applied to the target: 300 W, 500 W and 700 W. The frequency and the on-off time of the DC pulsed generator were 230 KHz and 1.9 us, respectively. The thickness of films was measured using a KLA Tencor P-10 surface mechanical profiler manufactured by KLA Corporation. 1 Technology Drive, Milpitas, CA 95035, USA and their sheet resistance values were determined by means of the four points technique, using a Napson Resistest mod. RT-8A. UV-VIS-NIR reflectance curves were obtained by a double-beam Perkin-Elmer mod. Lambda 900 instrument, equipped with a 10 cm diameter integrating sphere.  
Aluminium nitride-based cermets containing WN 300 W, 500 W and 700 W were produced by means of reactive co-sputtering processes, where the power supplied to the aluminium target was 3000 W.  
X-ray diffraction (XRD) analysis was performed with a Philips X'Pert PRO MRD diffractometer (manufactured by Philips Lelyweg 1 7602 EA Almelo The Netherlands.) working with CuK\(\alpha\) radiation (\(\lambda\) = 0.154056 nm), using a grazing incidence angle of 1.5\({}^{\circ}\). A scan range of 10-95\({}^{\circ}\) (28) was used. The diffraction data were used to calculate the crystallite size of the films using [PERSON]'s formula, d = \(\lambda\)/(\(\beta\) cos \(\theta\)), where \(\lambda\) is the wavelength of the X-ray used, \(\beta\) is the full-width half maximum measured at the \(\theta\) value of the peak. The morphology and the structure of the films were evaluated by AFM. Raman scattering experiments were performed using a micro-Raman system (inVia model of Renishaw) at room temperature, using as excitation the 514 nm line of an Ar ion laser at normal incidence. The nominal laser power used in these measurements was 20 mW. Typical spectrum acquisition time was limited to 50 s to minimize the sample heating. FTIR reflectance spectra were recorded on a Bruker Fourier transform instrument spectrometer (model Equinox 55), equipped with an integrating sphere and a MCT detector operating in the range 570-8000 cm\({}^{-1}\). A resolution of 8 cm\({}^{-1}\) was utilized. FTIR transmittance spectra were recorded with a Perkin Elmer Fourier transform instrument spectrometer equipped with a Deuterated Triglycine Sulfate (DTGS) detector operating in the 400-10,000 cm\({}^{-1}\), with a resolution of 2 cm\({}^{-1}\).  
The sessile drop method was used for measuring wetting behavior at room temperature, by means of a KRUSS DSA 100 instrument. Water and di-iodomethane small liquid droplets (6 \(\mu\)L) were formed on the end of the disposable needle (stainless steel, with a PP luer-lock connector, with a length of 38 mm and a diameter of 0.5 mm; Kruss NE 44), which were then carefully deposited onto the films' surface. Digital images of the droplet silhouette were captured with a high-quality camera, followed by the contact angle determination by numerically fitting the droplet image. The values reported herein are the average of at least five measurements on various parts of each sample.