Improvement of the heat resistance of epoxy casting resin for insulating spacers

New research has succeeded in producing more compact insulating spacers for gas insulated switchgear (GIS) by increasing the heat resistance (from 105/spl deg/C to 115/spl deg/C) of casting resin and by increasing the heat resistance of the interface bond between metal and resin. The newly developed resin is composed, like conventional types, of epoxy resin blended with alumina filler. In the new compositions, both increased thermal resistance and favorable mechanical properties are achieved by reducing shrinkage during curing and the viscosity of the matrix resin, and by increasing the content of alumina filler. The creep rupture characteristics of the newly developed resin at 115/spl deg/C equal those of conventional resin at 105/spl deg/C.