*2.2. Methods*

2.2.1. Coatings' Thickness Analysis

The coating thickness analysis was carried out on cross-sections of samples, obtained as described in the previous section. The coating thickness measurement was performed using a FEI QUANTA 400 FEG scanning electron microscope (SEM), provided with an EDAX Genesis energy dispersive X-ray spectroscopy microanalysis system. The same range of magnifications were used in all the pictures obtained by the SEM, allowing for a greater ease of comparison of phenomena between different samples. The values for coating thickness were obtained by calculating the mean value of the measurements registered during SEM analysis. A total of six different measurements across different zones for each of the coated tools were performed. EDS analyses were carried out with a beam potential of 15 kV; however, this was sporadically reduced to 10 kV to decrease the volume of interaction and reduce noise in the spectra. Although the reading accuracy of the EDS analyses as a quantitative evaluation is not the best, it was also used to confirm the chemical composition of the coatings, which was sufficient for this purpose and avoided employment of more costly technologies.
