Alumina filled nanocomposites for electrical insulation of power rotating machines

Silicone resins are widely adopted in outdoor and indoor electrical equipments. One of the main applications includes medium power rotating machines where they are used for the impregnation of rotor and stator windings. Due to the growing demand for compact insulation, the improvement of heat dissipation in such devices has recently become a very important issue and dielectric materials with enhanced thermal conductivity and, at least, unmodified mechanical and electrical properties are needed. In the present paper, we report results about the preparation and the morphological, thermal, mechanical and electrical characterization of new materials obtained by addition of nano-sized alumina (Al2O3) fillers to silicone matrix. Their measured physical properties are compared with those of the unfilled matrix, used as a reference, and the influence of the weight concentrations, ranging between 1 wt % and 7 wt % is fully discussed.