DETERMINATION OF MECHANICAL AND THERMAL PROPERTIES OF ELECTRICAL INSULATION MATERIAL AT 4.2 K

For the electrical insulation of superconducting magnets or magnet components, different insulation materials are used that ensure mechanical stability and good electrical insulation properties at low temperatures. Especially glass-fiber-reinforced or sand-filled epoxies are typical material composites that can be used at temperatures down to 4.2 K. For current lead construction within fusion technology, an optimized filled epoxy with respect to mechanical shear strength had to be identified. Therefore different steel/epoxy compositions where examined using the standardized three point bending method. The test specimen were formed putting five layers of glass-fiber lubricated with epoxy between two 1.4429 (316LN) steel frames. The epoxy facing surface of the steel was blasted with glass or corundum. A systematic investigation was performed using different epoxies to get an optimized mechanical performance. The results will be discussed together with data from a sand-filled epoxy compound. For both compounds beside the mechanical properties thermal conductivity and expansion are given in addition.