Provided is a graphene foam-based sealing material comprising: (a) a graphene foam framework comprising pores and pore walls, wherein the pore walls comprise a 3D network of interconnected graphene planes or graphene sheets; and (b) a permeation-resistant binder or matrix material that coats and embraces the exterior surfaces of the graphene foam framework and/or infiltrates into pores of the graphene foam, occupying from 10% to 100% (preferably from 10% to 98% and more preferably from 20% to 90%) of the pore volume of the graphene foam framework.

Provided is a graphene foam-based sealing material comprising: (a) a graphene foam framework comprising pores and pore walls, wherein the pore walls comprise a 3D network of interconnected graphene planes or graphene sheets; and (b) a permeation-resistant binder or matrix material that coats and embraces the exterior surfaces of the graphene foam framework and/or infiltrates into pores of the graphene foam, occupying from 10% to 100% (preferably from 10% to 98% and more preferably from 20% to 90%) of the pore volume of the graphene foam framework.

A liquid epoxy resin, a powdered metal and a hardening agent are provided as a filling material (S) and poured into an insert hole (82). The filling material (S) is in a liquid state under a normal temperature so as to make the filling material (S) handle easily in the filling work. The filling material (S) is hardened at a clearance between a bushing tool (12) and the insert hole (82). The filling material (S) is placed between the bushing tool (12) and the insert hole (82) to enhance a heat-conductivity therebetween. By heat treating a metallic mold die 80, it is possible to char the epoxy resin. This makes it possible to deposit the powdered metal (copper or the like) over an entire area of the clearance so as to highly enhance the heat-conductivity.