Preparation And Electrical Peoperties Of High Thermal Conductive Silicone Rubber Insulating Composites

Inorganic filler/silicone rubber compound materials due to its excellent weathering resistance, corrosion resistance, electrical insulation performance is widely used in high voltage, and insulation field. Because silicone rubber has light quality, easy processing, good flexibility and water resistance transference, it always is used for such as outdoor composite insulators. Silicone rubber substrate own low thermal conductivity and poor tensile performance, so filling with other inorganic material to improve the thermal conductivity of silicone rubber compound material are widely paid attention. Improving the thermal conductivity of silicone rubber composites materials can effectively decrease the local overheating aging caused by high voltage partial discharge to the materials, which has a practical application value.In order to prepare high thermal conductive silicone rubber compound material, filled with micro Al2O3 (0.5～3μm), micro Si3N4 (0.3～3μm), nano-Al2O3 and nano-AIN respectively, with the blending method, different thermal conductive silicone rubber compound materials were prepared. But there was no very ideal material with good thermal conductivity, good mechanics property and stable electrical insulation with these compound materials. Three-component rubber matrix micro-nanocomposites consisting of nanometer alumina (Al2O3), micron silicon nitride (Si3N4), and methyl vinyl silicone rubber were fabricated by blending method which the total volume fraction was fixed at 30vol%. It's found that with the same volume fraction, the thermal conductivity of all the micro-nano composites had remarkable improvement compared with that of the composite filled with micro Si3N4. Especially, when the volume ratio of micro Si3N4 and nano-Al2O3 was 26/4, the thermal conductivity (1.64W/m.k) is three times than that of the composite with 30% micro Si3N4 (0.52 W/m.k). At the same time, the mechanics of the three-component rubber matrix micro-nanocomposites were improved with the increasing of the nano- Al2O3(when micro-nano ratio reach 26/4,the hardness, tensile strength and elongation at break of the composites all can reach the mechanical performance requirements of insulator standards). Also the three-component rubber matrix micro-nanocomposites had excellent and stable insulation performance than that of the micron Si3N4/silicon rubber composites.