Application of Ceramic Encapsulated Castable in High-Temperature Electromagnetic Coils

With nano alumina and a small amount of nano silica as the main raw materials, the ceramic encapsulated castable was prepared by nano particle surface modification process. The structure, thermal stability and encapsulation properties of the ceramic encapsulated castable were studied. The electromagnetic wire and ceramic skeleton were encapsulated with the ceramic encapsulated castable and were calcined at 550 ℃. The insulation properties and voltage resistance of the encapsulated electromagnetic coil were studied. The results show that after calcination at 800 ℃, the solvent in the ceramic encapsulated castable volatilized, the organic dispersant and the binder decomposed, and the structure of the main component including nano alumina and silica inorganic materials basically did not change; the ceramic encapsulated castable had a high temperature resistance grade. After calcination at 550 ℃, the ceramic encapsulated castable was closely combined with the quartz fiber of electromagnetic wire and with the ceramic skeleton to form a complete packaging structure. The electromagnetic coil with ceramic encapsulated castable could withstand the voltage of more than 2 000 V at room temperature, and the insulation resistivity after aging at 550 ℃ for 100 h was 8.5×10⁸ Ω · m; the encapsulated electromagnetic coil showed good voltage resistance and insulation performance.