Multilayer insulating material and process for production thereof

摘要

By bonding a graphite sheet possessing tightness to at least one surface of carbon fiber felt sheet possessing gas permeability by means of a carbonaceous binder, a multilayer thermally insulating material suitable for use in a heating furnace employing a nonoxidizing atmosphere is obtained. This insulating material has mechanical strength which does not decrease with a long period of use and gives rise to little contamination of articles being heated in the furnace.