# Effect of the Insulating Layer on the Properties of SMC Inductors
## 5 Conclusions  
The use of SMC materials in the inductors sector remains a challenge. Although some materials are already available on the market, the solution panorama is vast. As demonstrated in this work, the insulating coating plays the primary role in both toroidal and rod inductors. The analysis proved that the high-insulating behavior of the layer/binder is important, and the binder content plays a secondary role. The organic layer has better properties at the same binder content than the inorganic nano-ferrite coating. It seems that the magnetic insulating coating penalizes the inductance value. The increased epoxy binder content reduces all magnetic properties, but the total iron losses are inferior to minor resin content. Such phenomenon is due to low eddy currents; on the other hand,  
Figure 16: The Q factor of the rod samples of proposed SMC materials.  
the hysteresis losses increase with the binder content, which involves a reduction in the \(Q\) factor. However, an increment of the binder content shifts the \(Q\) factor peak towards high-frequency values. Therefore, the increment of the binder would be advisable, but a high reduction in magnetic properties and possible mechanical deformation necessitates a careful design.  
The phosphorylated SMC showed a good \(Q\) factor and operating interval for medium-high frequency applications. On the other hand, the initial magnetic permeability was the lowest where epoxy SMC 1-800 showed promising results and the probability of application in specific applications such as, for instance, instrument transformers. Additionally, the same material had a good \(Q\) factor at a low frequency and can be adopted in the audio sectors.  
A comparison with soft ferrites is not achievable at the moment. Therefore, the only advantage concerns the mechanical aspects of producing complex shape inductance.  
In this work, a preliminary analysis is made concerning the study of SMC coatings for inductance applications. Other coatings will be explored in the future, adopting new solutions: multifunctional and hybrid layers, resin filled with particular particles, granulocyte effect, different inorganic layers, additive manufacturing, etc. The volume content will be included to paragon different types of SMC coatings. Moreover, a supply system will be implemented with the possibility of acquiring further experimental data. In addition, a detailed microstructural and compositional analysis (SEM-EDS investigation) will be performed.  
Conceptualization, E.P. and F.F.; methodology, E.P. and F.F.; software, F.F.; validation, E.P. and L.F.; formal analysis, E.P. and F.F.; investigation, E.P. and F.F.; resources, L.F.; data curation, E.P. and F.F.; writing--original draft preparation, E.P., F.F. and L.F.; writing--review and editing, E.P., F.F. and L.F.; visualization, E.P.; supervision, L.F. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Not applicable. Not applicable. The part of research activities developed by [PERSON] has been conducted through the Operative National Program (PON) for Research and Innovation 2014-2020, M.D. 1062 (10 August 2021), Action IV.6--\"Research contracts on Green topics\". The authors declare no conflict of interest.