A thermal barrier for extremely high temperature applications consists of a carbon
fiber core and one or more
layers of braided
carbon fibers surrounding the core. The thermal barrier is preferably a large
diameter ring, having a relatively small cross-section. The thermal barrier is particularly suited for use as part of a joint structure in
solid rocket motor casings to protect low temperature elements such as the primary and secondary elastomeric O-ring seals therein from high temperature gases of the
rocket motor. The thermal barrier exhibits adequate
porosity to allow pressure to reach the radially outward disposed O-ring seals allowing them to seat and perform the primary sealing function. The thermal barrier is disposed in a cavity or groove in the casing joint, between the hot propulsion gases interior of the
rocket motor and primary and secondary O-ring seals. The characteristics of the thermal barrier may be enhanced in different applications by the inclusion of certain compounds in the casing joint, by the inclusion of RTV
sealant or similar materials at the site of the thermal barrier, and / or by the incorporation of a
metal core or plurality of
metal braids within the carbon
braid in the thermal barrier structure.