## 3 Results and Discussion
### Results of Material Performance for Potential Application as IT-SOFC Sealants  
#### 3.3.1 Results of the XRD and FESEM Analyses of the Raw and Sintered Samples  
In order to verify their chemical stability in contact with IT-SOFC fuel at operating temperatures, the raw and sintered GC samples were analyzed before and after exposure to CO\({}_{2}\) gas at 700 \({}^{\circ}\)C in terms of the crystal-phase composition (XRD) and microstructural characteristics (FESEM). The resulting XRD diagrams and FESEM images are given in Figure 10.  
Figure 10: _Cont_.  
Figure 10: XRD diffractograms of all sintered samples (GC\({}_{0}\), GC\({}_{5}\), GC\({}_{10}\), GC\({}_{15}\), and GC\({}_{20}\), respectively) before and after exposure to CO\({}_{2}\) gas at 700 \({}^{\circ}\)C (left) and FESEM images of raw samples (**a**) and samples sintered at 700 \({}^{\circ}\)C and exposed to CO\({}_{2}\) (**b**), simultaneously (right).  
From the XRD results, it can be noticed that all the sintered GC samples did not exhibit significant changes in crystal-phase composition after exposure to the CO2 environment. Identical phases with rather narrow and sharp peaks were detected. However, an additional loss of amorphous phase and better structural arrangement in the angular range of 5-30\({}^{\circ}\) 20 were observed in the sintered samples, especially GC0 and GC10, after the reactivity test's completion.  
According to the SEM images presented in Figure 10, there was no evident, noticeable difference in the microstructure of the raw samples and the samples submitted to the reactivity test. Agglomerates of about 20-50 \(\upmu\)m in diameter and irregularly shaped grains of about 5 \(\upmu\)m in diameter were dominant in the structure of the samples exposed to gas CO2 at 700 \({}^{\circ}\)C. In most samples, the presence of microporosity was observed after conducting the tests. Despite the existence of visible pores, these samples showed satisfactory strength and compactness, which means that the porosity was superficial and that the grains were actually tightly bound within the sample.  
3.2 Results of the Open Circuit Voltage (OCV) Test--Leakage Detection of a Single Laboratory Fuel Cell  
A single laboratory fuel cell with the applied sealant sample before and after the performed OCV test is shown in Figure 11. As can be clearly noticed, the sealant did not retain structural integrity after the treatment since large cracks occurred and the sample completely disintegrated. Therefore, hermetic sealing between the ceramic components of the cell, i.e., the electrolyte and the fuel tube, cannot be provided.  
This experimental failure indicated that the studied glass-ceramic material is not suitable for very complex and precision-demanding IT-SOFC technology. Also, this statement is in accordance with the previous assumption that the obtained results of mechanical properties of these samples are insufficient for this application. However, certain modifications, in view of the procedure of preparation or the sharing and selection of components, might result in achieving rugged and stable joints between the ceramic parts of the fuel cell. Therefore, the major future aspects of this research should be aimed at finding a proper solution for the application of such modified waste-containing materials as sealants in IT-SOFC technology and thus expanding their usability to this industry as well.