Interfaces: To be avoided or to be treasured? What do we think we know?

Abstract

Whatever our specific field of expertise, we all have to deal with interfaces, whether we are involved in designing the large interfaces in high voltage cable accessories or whether we try to tailor the interface properties on a very small scale in nanocomposites. Whereas many of us study the properties of new insulating materials and their bulk properties, this paper focuses on what we think we know about interfaces and how to deal with them, and on where we definitely lack knowledge. The storyline will go from the scale of centimeters, to micrometers and it will end at nanometer scale. It will be shown that the way we need to look at interfaces changes drastically when we go down in size.

Space Charge Accumulation at Material Interfaces in HVDC Cable Insulation Part I—Experimental Study and Charge Injection Hypothesis

“…Therefore, limiting the amount of charge that is injected into the insulation is crucial. Within these systems, cable accessories, such as land joints, field joints, and terminations introduce physical interfaces [2] between the cable insulation surface and the pre-molded accessory component. A joint is illustrated in Figure 1, displaying this interface.…”

“…The data is normalized against the remolded surface 2. Average of the 100 highest FEF values from the histogram 3.…”

Introducing particle interphase model for describing the electrical behaviour of nanodielectrics

“…The layers that are adjacent to the interface might be affected by being next to different phase and to the interactions that occur between the two phases. These interactions are proposed to result in the formation of an interphase region with modified properties [18][19][20]. Consequently, as the size of the particles becomes smaller, the specific surface interfacial area will increase and, consequently, any interphase regions will constitute a commensurately larger volume fraction of the whole system which, it has been argued, explains how the macroscopic properties of nanocomposite differ from those of either component in isolation.…”

Investigation on electromagnetic characteristics, microwave absorption, thermal and mechanical properties of ferromagnetic cobalt–polystyrene composites in the X-band (8.4–12.4 GHz)

“…The maximum of loss factors are shied towards lower part of the X-band frequency with increasing the cobalt content, which is in compliance with the other reported experimental results. 47,53,54 The increasing trend of loss factor with the addition of cobalt content may be explained from the fact that the low loss PS is converted into the lossy dielectric when it is mixed homogeneously with high concentration of cobalt llers thus giving rise to high values of dielectric losses. The losses could also be attributed to the interfacial polarization developed at the metal-insulator interface (Maxwell-Wagner theory of interfacial polarization), where the electric charges are accumulated and increased by increasing the cobalt content.…”