Several Properties of Impregnating Epoxy Resins Used for Superconducting Coils
In order to find the most appropriate vacuum-pressure impregnating epoxy resin for superconducting coils, three types of epoxy resin were experimentally investigated from various points of view. Those epoxy resins were amine curing type A, anhydride curing type B with tertiary amine accelerator, and anhydride curing type C without accelerator.
From the investigations, resin A was found to be superior in thermal shock resistance than resins B and C because of its large tensile fracture strain at cryogenic temperature and its small cure shrinkage. However, the test coil impregnated with resin A experienced more repeated premature quenches than the coil impregnated with resin C. This result might be related to the crackings which started from microscopic defects, and which occurred gradually in resin A compared with resins B and C. Moreover, the viscosity of resin A increased more rapidly during the impregnating process than that of resins B and C, so that resins B and C appear to be more appropriate for large superconducting coils than resin A.
KeywordsAdhesive Strength Cryogenic Temperature Acid Anhydride Thermal Contraction Training Characteristic
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