Enhanced Thermal Conductivity and Insulation Properties of Mica Tape with BN-Coated Meyer Bar Technology

In high-voltage generator, mica tape is the most critical and main stator coil insulation material. The improvement of its thermal conductivity and insulation properties can extend the service life of the generator while improving the operational stability of the main insulation structure of the high-voltage generator. Consequently, improving the thermal conductivity and insulation properties of mica tapes has a decisive role in improving the reliability of the main insulation of high-voltage generator. In this paper, a Meyer bar coating method is used to uniformly coat boron nitride (BN) with high thermal conductivity and excellent insulation properties onto the mica tape surface using polyvinylpyrrolidone (PVP) as the binder. With the increase of BN content, the thermal conductivity and breakdown strength of mica tape are improved. At 25 °C, the out-of-plane thermal conductivity increased from 0.171 W/(m.K) to 0.265 W/(m.K) when the BN content reached 2 wt. %, an improvement of 55%, and the DC breakdown strength increased from 93.13 kV/mm to 101.24 kV/mm, an improvement of 8.71%. The thermal stability and dielectric properties are almost constant. This work provides a reference for improving the electrical and thermal properties of the main insulation of generator and further developing high thermal conductivity insulation materials.