Thermal Conductivity of Heterogeneous Polymer Composite Materials Filled with Micro- and Nano-Sized Inorganic Particles

The article presents the results from studying the thermal conductivity of heterogeneous polymer composite materials filled with micro- and nano-size inorganic particles in various concentrations. The aim of the studies is to develop electrical insulation materials featuring high thermal conductivity for electrical machine windings. Electrical insulating impregnating varnish EP-9150 and insulation based on the electrical insulating tape Elmikaterm 52409 were used as polymer composite materials, in which the impregnating varnish EP-9150 was used as a binding component. KhK Elinar LLC is the manufacturer of these materials. Inorganic micro-sized particles of hexagonal boron nitride, aluminum oxide, and nano-sized particles of aluminum oxide were used as a filler that increases the polymer composite material thermal conductivity, which were introduced directly into the impregnating varnish in manufacturing the samples. A technology for manufacturing varnish and insulation samples has been developed. A comparative analysis of the dependence of material thermal conductivities on the concentration of micro- and nano-size particles and their combinations is carried out. The dependence of the dielectric loss angle tangent on temperature is determined. Structural studies of material samples were carried out. The study results made it possible to identify technical features and provide practical recommendations for working out approaches to the development of electrical insulation materials featuring high thermal conductivity.