## 3 Results and Discussion  
With the methodology described previously, we obtained regular coatings for all the thermally treated and laser-irradiated samples. The surface micrographs of the Al\({}_{2}\)O\({}_{3}\)/glass-ceramic coating are shown in Figure 2. The path laser is evident in the laser annealing surfaces. The laser path's definition on the surface is higher for higher laser density power (Figure 2c). Figure 3 shows the surface morphology of the SSZ03 sample. The SEM images reveal a change in the surface profile created after laser irradiation on the Al\({}_{2}\)O\({}_{3}\)/glass-ceramic coating. The glass ceramic resembles a kind of broken glass on top of the alumina film. The coating layer's morphology is not uniform in the microscopic range, and the cracked surface is probably due to differences in the thermal behavior. The thickness of the alumina coating with similar manufacturing parameters is between 400 and 500 \(\upmu\)m, as shown in Figure 4, in which the same authors have used Inconel 718 alloy as a substrate. The SEM micrograph presented in Figure 5a corresponds to the surface image over the Al\({}_{2}\)O\({}_{3}\)/glass-ceramic coating. In two different positions on the surface, the composition is described by the EDS spectra (Figure 5b,c). It is evidenced that position 1 corresponds to the Al\({}_{2}\)O\({}_{3}\) layer and position 2 to ZrO\({}_{2}\)-SiO\({}_{2}\). Figure 6a corresponds to an image of a sample surface annealed by irradiation using 1.38 W/cm\({}^{2}\) of laser power density and following the design mentioned above. The surface exhibits differences between sections which are irradiated and those not irradiated. The modifications induced by the laser are structural, and the thermo-optic response supports this statement. Figure 6b shows the image obtained from the infrared emission induced by 520 nm radiation. In this map, the path pattern of the laser can be observed, showing the differences between the irradiated areas, as well as the homogeneity in the laser treatment carried out. This signal is associated with different non-radiative mechanisms and heat diffusion capabilities. Figure 1: Computer-aided design image of the channel written with CO\({}_{2}\) laser system. Figure 2: Imaging of the Al\({}_{2}\)O\({}_{3}\)/glass–ceramic composite coating, treated with different power densities of CO\({}_{2}\) laser irradiation: (**a**) without irradiation, (**b**) 0.69 W/cm\({}^{2}\) and (**c**) 1.04 W/cm\({}^{2}\). X-ray diffraction patterns of Al\({}_{2}\)O\({}_{3}\)/SiO\({}_{2}\)-ZrO\({}_{2}\) and Al\({}_{2}\)O\({}_{3}\) coatings both deposited on the brass substrate are presented in Figure 7. Figure 7a showed traces of tetragonal zirconia crystals at 30.2\({}^{\circ}\), 50.4\({}^{\circ}\), 50.7\({}^{\circ}\) (20) reported in the JCPDS-ICDD data (set no. 50-1089). The tetragonal ZrO\({}_{2}\) diffraction peaks correspond to the crystalline planes (011), (112) and (020), respectively, and the phase is conserved even when the sample reaches room temperature. Like the yttria-stabilized zirconia (YSZ), the most common material used as the ceramic layer, this demonstrates the well-known stabilizing effect in the ZrO\({}_{2}\) structure, promoting the formation of high-purity tetragonal zirconia [19; 20; 21]. On the other hand, although the Al\({}_{2}\)O\({}_{3}\)/brass substrate sample displayed both \(\alpha\)-brass and \(\beta\)-brass phases, compared with the Al\({}_{2}\)O\({}_{3}\)/SiO\({}_{2}\)-ZrO\({}_{2}\)/brass substrate, only \(\alpha\)-brass was still observed [22]. This indicates that the \(\beta\)-brass is present or formed when the Al\({}_{2}\)O\({}_{3}\) is deposited (\(\gamma\)-Al\({}_{2}\)O\({}_{3}\)), and when glass-ceramic and thermal treatment are used, this phase is transformed into \(\alpha\)-brass. Figure 8 shows the X-ray diffraction patterns for the Al\({}_{2}\)O\({}_{3}\)/glass-ceramic composite coating system with different post-annealing treatments.