## 4 Conclusions  
The analysis of the obtained results indicates that the main goal of this work, which was to confirm that the hybrid binder based on tetraethoxysilane and 1,2-bis(triethoxysilyl)ethane can successfully consolidate the transformer core made of a Met-glas amorphous steel ribbon, has been achieved. It has been proven that the metal substrate coated with the hybrid binder has a higher corrosion resistance compared to the raw amorphous metal; therefore, the service life of the treated ribbon can be extended. It has been shown that the dielectric constant of the sol-based hybrid binder layer shows a decreasing tendency at higher frequencies for all tested temperatures (25, 50, 75, and 100 \({}^{\circ}\)C), and, at the most interesting frequencies, namely, 50 Hz and 60 Hz, the dielectric constant fluctuates slightly in the range of 6.7-6.9, which indicates no significant influence of temperature. Furthermore, the results showed that, over the entire operating flux density range (1-1.5 T) and at both tested frequencies (50 Hz and 60 Hz), the core bonded with a silane-based binder exhibits significantly lower core losses compared to the unbonded reference core. At saturation flux (about 1.5 T) and 50 Hz, the bonded core losses are 23% lower than the reference core losses, while, at 60 Hz, the reduction is 19%. The literature shows that the interlaminar application of an organic metallic binder results in a core loss reduction of up to 26% compared to the edge-glued core with the epoxy resin [16]. When the bonding powder was applied on the edge of the core by plasma-arc spraying, the core loss reduction was only 11-15% compared to the untreated core [17]. The noise analysis in our study shows that the sol-bonded magnetic core becomes noisy above 1.4 T, while the reference already exceeds the background sound level at 1.25 T. The difference at the saturation flux (approximately 1.5 T) is 6 dB, which means that the reference core is two times noisier than the bonded core. In addition, the sound pressure level in the range from 100 Hz to 10 kHz is generally lower for the sol-bonded  
Figure 6: Frequency spectrum of sound pressure level for the reference core and the core bonded with sols, for the cores which were excited with a magnetic flux of 1.54 T (saturation), at a frequency of 50 Hz. core compared to the reference core. [PERSON] at al. showed in [16] that changing the epoxy binder at the core edge to an organometallic binder between the core laminations reduces the sound power by 21% at 50 Hz and 1.35 T. Interesting results can be found in [21], where three types of cores were tested, one in which the laminations were tied around with tape, the second glued with the epoxy resin on the edge, and the third a reference one without any bonding. Surprisingly, it can be noted that the reinforcement of the core did not reduce the audible noise, and, so, in the case of the tape-bonded core, the sound power was slightly higher than in the case of the reference core, while the core glued with epoxy resin had an average noise higher by 10 dB. Taking into account all the above conclusions, it is evident that the proposed hybrid binder based on the double-layer TEOS/BTSE system can be successfully applied to the magnetic core made of an amorphous metal ribbon. This is valuable information from the application point of view, as it opens the possibility of producing a more efficient transformer core, which is also characterized by a reduced level of emitted audible noise. It should be emphasized that the applied conditions, such as manual core preparation, sol application, and drying in an air atmosphere, and being below the Curie temperature allowed us to conclude that the scaling process of this technology should be successful. Moreover, the introduction of automated process elements, such as unwinding/winding, as well as pulling the ribbon through acetone and sol solutions at a well-defined speed, should provide even better core properties, because the obtained layers will be more uniform. Conceptualization, A.R.