| 摘要 |
PURPOSE:To obtain a porous insulation covering which has realized a reliable degasification process on a coil of vacuum electric apparatus by impregnating a coil formed of wound wire with an impregnant containing silicon compound and synthetic mica, then molding it, and thereafter conducting heat treatment. CONSTITUTION:An impregnant used is obtained by mixing a silicon compound and synthetic mica of 250-400 mesh with the weight ratio of 1:0.8 and then kneading them by means of a ball mill and thereafter reducing it with an individual or mixed solvent of adequate organic solvent, for example, of xylene, butylcellusolubu, cellusolubu acetate and adjusting the viscocity. A coil is impregnated with the impregnant and is then baked at a temperature of 300 deg.C or higher. Thereby, a small amount of fluorine compound vaporized from synthetic mica, for example, SiF4, KF, etc., partly melts SiO2 which is a decomposed biproduct of silicon compound to form an aggregate ceramics. The amount of gas released from an insulation covering baked as explained above is vary small and therefore it is certain to attain a high degree of vacuum in a vacuum apparatus using such a coil.
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