关键词: Bi-2212 超导磁体绝缘, 氧化铝纤维, 空气热处理, 除碳

Abstract:  Alumina fiber products with 72%γAl₂O₃+28%SiO₂ were selected as insulating fiber materials of Bi-2212 superconducting magnet, and air heat treatment was carried out for carbon removal. The thermal weight loss, fiber surface morphology, and fiber strength of the three kinds of fiber materials, i.e. alumina fiber ribbon A with 25mm width and 0.2mm thickness, alumina fiber ribbon B with 25mm width and 0.35mm thickness and alumina fiber bundle C with 200tex, 3 strands and 80 twist, were analyzed and characterized by means of strength tests, SEM and TG-DSC. The results show that they have good temperature resistance, and no heat absorption or exothermic peak of crystal phase transformation is found during the thermogravimetric process. After air heat treatment, the surface sizing agent is oxidized and volatilized, the fiber is exposed without defects, the diameter change is not obvious, the strength drop is not more than 25%, and the insulation performance is improved. The analysis results show that the insulation performance of alumina fiber can be effectively improved by air heat treatment at 600℃ lasting 2 hours.

Key words: Bi-2212 superconducting magnet insulation, Alumina fiber, Air heat treatment, Carbon removal