## 3 Results and Discussion
Figure 8a shows only the sample annealed at 850 \({}^{\circ}\)C at 60 min without any laser post-annealing; Figure 8b shows the sample annealed at 850 \({}^{\circ}\)C at 60 min and under a CO\({}_{2}\) laser using 0.69 W/cm\({}^{2}\) power density for 1 min; Figure 8c shows the sample annealed at 850 \({}^{\circ}\)C and under a CO\({}_{2}\) laser using 1.04 W/cm\({}^{2}\) power density for 1 min. All spectra display evidence of ZrO\({}_{2}\) formation,  
Figure 4: SEM micrographs of the alumina SEM image of alumina deposited on Inconel 718. Figure 3: Scanning electron microscope (SEM) micrographs of the SSZ03 sample at different magnifications: (**a**) 480\(\times\) and (**b**) 1620\(\times\). which is stable at ambient temperature. It is important to note that it was possible to obtain stable tetragonal ZrO\({}_{2}\) in the SiO\({}_{2}\)-ZrO\({}_{2}\) coating by spin-coating and the thermal treatment applied at 850 \({}^{\circ}\)C for 60 min. The fitting procedure of the diffractograms indicates that the dominant structure is the tetragonal phase for ZrO\({}_{2}\), especially when CO\({}_{2}\) laser irradiation energy is increased (to see 20 = 30.2\({}^{\circ}\)). The sample annealed at 850 \({}^{\circ}\)C for 60 min (Figure 8a) in the oven shows differences from the same sample with CO\({}_{2}\) laser post-annealing using 0.69 W/cm\({}^{2}\) (Figure 8b) and 1.04 W/cm\({}^{2}\) (Figure 8c) power density for 1 min. In Figure 8a, the as-sprayed \(\gamma\)-Al\({}_{2}\)O\({}_{3}\) is in a metastable phase, which is due to the rapid cooling rate of the process of plasma spraying, wherein alumina powder injected into the high temperature plasma is melted and entrained in the gas stream and is then accelerated and impinges on the substrate to form the coating [23]. CO\({}_{2}\) laser annealing allows the transformation of \(\gamma\)-Al\({}_{2}\)O\({}_{3}\) into thermodynamically stable \(\alpha\)-Al\({}_{2}\)O\({}_{3}\), this transformation being more visible at higher power densities. Figure 8b,c show the XRD patterns typical of the stable corundum structure reported in JCPDS-ICDD data (set no. 46-1212). Figure 5: (**a**) SEM micrograph of the SSZ03 sample presenting position 1 and 2 for further EDS analysis, (**b**,**c**) EDS analysis over two different positions (1 and 2), respectively. Figure 9 shows the PL spectra of SiO\({}_{2}\)-ZrO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) coatings without laser post-annealing and annealed for 1 min with different laser power densities: 0.69, 1.04, 1.38 W/cm\({}^{2}\). In this figure, the effect of laser power on the optical response is shown. All annealed samples exhibit a doublet at around 694 nm and broad and weak emission bands at lower energies, in which intensities and sharpness are enhanced as the laser power increases. The origin of these emission bands is not yet established. We found reports that the spectral emission at higher energies is due to the F+ center (330 and 415 nm). Chromium impurity in the Al\({}_{2}\)O\({}_{3}\) lattice is characterized by two bands of absorption (3.1 and 2.2 eV), and one sharp emission structure peaked at 1.8 eV (696 nm), quite near the emission peak obtained by PL in this work [4,22]. According to this report, for the materials involved in the Al\({}_{2}\)O\({}_{3}\)/glass-ceramic composite coatings, the PL emission is associated with silica and zirconia in the Al\({}_{2}\)O\({}_{3}\) bond coat. Figure 6: Surface morphology of the SSZ03 sample with laser annealing using 1.38 W/cm\({}^{2}\) of power density: (**a**) optical microscopy image and (**b**) mapping of infrared emission induced by 520 nm radiation. Figure 8: XRD pattern of Al\({}_{2}\)O\({}_{3}\)/glass–ceramic coating on CuZn substrate. (**a**) Only annealed at 850 \({}^{\circ}\)C at 60 min without any laser post-annealing; (**b**) annealed at 850 \({}^{\circ}\)C at 60 min and under CO\({}_{2}\) laser using 0.69 W/cm\({}^{2}\) power density for 1 min; (**c**) annealed at 850 \({}^{\circ}\)C and under CO\({}_{2}\) laser using 1.04 W/cm\({}^{2}\) power density for 1 min.