High-thermal-conductivity strong-insulation epoxy composite material for solid-state transformer under low doping amount and preparation method thereof

Abstract

The invention discloses a high-thermal-conductivity strong-insulation epoxy composite material for a solid-state transformer under a low doping amount and a preparation method thereof. The preparationmethod comprises the following steps: 1) preparing core-shell structure BN@SiO2 micron particles, and carrying out coupling agent surface modification and ball-milling treatment on nano BN; 2) preparing 100 parts of epoxy resin, 80 parts of a curing agent, 1 part of an accelerant and 20-80 parts of a micro-nano filler system, wherein nano BN accounts for 1-5wt% of the specific gravity of the filler system; (3) mixing the components in the step (2), and carrying out dispersion and defoaming treatment by virtue of an autoroatation and revolution stirrer; and 4) pouring the mixture obtained in the step 3) into a mold, and heating and curing the mixture in a drying box. Through a micro-nano co-doping technology, micron particles adopt a core-shell structure, the surfaces of the nano particlesare modified, and the epoxy-based composite material with excellent electrical and thermal properties can be obtained under the selected co-doping ratio; in addition, the preparation method is simplein step, low in filler doping amount, low in cost and suitable for industrial production.

Description

technical field [0001] The invention belongs to the technical field of heat-conducting and insulating composite materials, and in particular relates to a high-heat-conducting and strong-insulating epoxy composite material for solid-state transformers with low doping content and a preparation method thereof. Background technique [0002] In recent years, with the increase of power consumption, the load of the power grid has become larger and larger. Power electronic transformers have attracted people's attention because of their huge development potential in distributed power generation systems and new energy power generation. However, in the solid-state transformer part of the power electronic transformer, the hysteresis loss of the iron core, the Joule heat of the coil, and the loss and heat generation of the insulating material itself will cause a local temperature rise of 150-170°C, which will affect the long-term stable operation of the equipment. [0003] As the main in...

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Problems solved by technology

However, in the solid-state transformer part of the power electronic transformer, the hysteresis loss of the iron core, the Joule heat of the coil, and the loss and heat generation of the insulating material itself will cause a local temperature rise of 150-170°C, which will affect the long-term stable operation of the equipment.

[0003] As the main insulating medium of solid-state transformers, epoxy resin has the advantages of good insulation performance, easy processing and molding, high hardness, and stable performance, but the intrinsic thermal conductivity of epoxy is not high (only 0.20-0.22W / (m·K )), which limits the heat dissipation efficiency of devices and power equipment. At the same time, during the operation of solid-state transformers, epoxy resin, as the main insulating medium, is often in a multi-field coupling environment such as electricity, heat, and machinery. The insulation performance puts forward higher requirements, so the study of high thermal conductivity and strong insulation epoxy composite materials for solid-state transformers is of great significance to the long-term stable operation of solid-state transformers

[0004] As far as the current research is concerned, the general means to achieve high thermal conductivity is to increase the doping amount of fillers and construct different structures, such as multi-layer structures, 3D network structures, etc., but what cannot be avoided is that the doping amount of fillers is large, Correspondingly, insulation properties such as breakdown field strength will decrease

The Chinese invention patent with the application number 201710544833.8 discloses a high thermal conductivity insulating epoxy resin composition and its preparation method, but it does not pay enough attention to the electrical insulation strength, and does not discuss the improvement of the breakdown field strength. Secondly, the adhesion needs to be improved. At the same time, the preparation process is relatively complicated, and the filler content is high, which is easy to form holes in the matrix and endanger the insulation performance; the Chinese invention patent with application number 201710232591.9 discloses a high thermal conductivity epoxy resin-based alumina-boron nitride micro-nano composite insulation material, but it does not involve the electrical insulation strength of the composite material. At the same time, the filler doping content is relatively high. In one embodiment, the filler content is as high as 78wt%. It is easy to introduce pores during the preparation process, which will bring harm to the dielectric properties. At the same time, the high The amount of doping poses certain difficulties for industrial production

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