Abstract
As a lightweight and highly insulating composite material, epoxy resin syntactic foam is increasingly widely used for insulation filling in electrical equipment. To avoid core burning and cracking, which are prone to occur during the casting process, the epoxy resin-based syntactic foam insulation materials with high thermal conductivity and low coefficient of thermal expansion are required for composite insulation equipment. The review is divided into three sections concentrating on the two main aspects of modifying the thermal properties of syntactic foam. The mechanism and models, from the aspects of thermal conductivity and coefficient of thermal expansion, are presented in the first part. The second part aims to better understand the methods for modifying the thermal properties of syntactic foam by adding functional fillers, including the addition of thermally conductive particles, hollow glass microspheres, negative thermal expansion filler and fibers, etc. The third part concludes by describing the existing challenges in this research field and expanding the applicable areas of epoxy resin-based syntactic foam insulation materials, especially cross-arm composite insulation.
Highlights
With the development of materials and technology for electrical equipment, composite insulation materials have been used in domestic transformer substations and lines. They have replaced the traditional porcelain insulation materials in AC and DC power systems due to their unique antifouling performance and superior properties. These electrical insulation materials have more stringent requirements on inner filling materials because they operate outdoors for many years and bear strong electric fields and erosion by harsh weather conditions, and they are affected by factors such as high and low-temperature changes, wind, rain, and snow
Epoxy resin-based syntactic foams can be employed in solid buoyancy materials [2] to effectively reduce their water absorption [3,4], and can greatly improve the compressive strength of lightweight buoyancy materials
Conclusions and Prospect would be better used in electrical equipment after being researched and explored further in future studies as a reinforcing phase of composites
Summary
With the development of materials and technology for electrical equipment, composite insulation materials (insulators, insulation cross-arms) have been used in domestic transformer substations and lines They have replaced the traditional porcelain insulation materials in AC and DC power systems due to their unique antifouling performance and superior properties. Epoxy resin-based syntactic foams can be employed in solid buoyancy materials [2] to effectively reduce their water absorption [3,4], and can greatly improve the compressive strength of lightweight buoyancy materials. This feature is suitable for water diffusion leakage current testing of insulation materials used in electrical equipment. Even if the heat transfer is very fast in the fillers, the thermal resistance of the filler–matrix interface limits the improvement of the thermal conductivity of composites
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