Abstract: The fluororesin composite material with high mechanical strength characteristics and wear resistance comprising 99 to 40 parts by weight of a fluororesin, e.g. polytetrafluoroethylene, and 1 to 60 parts by weight of a carbon fiber wherein the carbon fiber has an interplanar spacing d(002) of 3.36 to 3.45 .ANG., a c-axis crystallite dimension (Lc) of 35 to 400 .ANG. and an a-axis crystallite dimension (La) of 40 to 800 .ANG.. The carbon fiber obtained by heat-treating a precursor fiber, previously infusiblized or flame resistance-treated, in an inert gas containing 20 to 5,000 ppm of an oxygen-containing gas at a temperature of 2,500.degree. to 3,00.degree. C.

Abstract: Polymer-type fibers longitudinally shrinkable by calcination and other carbon fibers are mixed and mechanically compressed and integrated by a needle punch, and the polymer-type fibers are then shrunk when calcined. Thus, there is obtained high bulk density carbon fiber felt having average bulk density of 0.1 g/cm.sup.3 or more without the carbon fiber felt impregnated with, resin and compressingly molded. The density of carbon fiber felt may change in the thickness direction thereof. The high bulk density carbon fiber felt may be used as a thermal insulator for a high-temperature furnace, a heat-resisting cushioning material, and a material for the electrode of a secondary battery.

Abstract: The present invention provides: (1) a formed tubular thermal insulator comprising a felt piece of carbon fibers spirally wound to form a laminate of felt layers integrally bonded to each other with the carbonized substance present between the felt layers with substantially no wavy deformation of spiral winding form, and (2) a process for preparing a formed thermal insulator, the process comprising spirally winding a felt piece of carbon fibers and a film and/or net with a carbonizable resin inserted therebetween while applying a tensile force on the film and/or net to form a laminate, followed by curing and carbonization.

Abstract: Polymer-type fibers longitudinally shrinkable by calcination and other carbon fibers are mixed and mechanically compressed and integrated by a needle punch, and the polymer-type fibers are then shrunk when calcined. Thus, there is obtained high bulk density carbon fiber felt having average bulk density of 0.1 g/cm.sup.3 or more without the carbon fiber felt impregnated with resin and compressingly molded. The present invention also provides high bulk density carbon fiber felt of which bulk density is changed in the thickness direction thereof. The high bulk density carbon fiber felt may be used as a thermal insulator for a high-temperature furnace, a heat-resisting cushioning material, and a material for the electrode of a secondary battery.

Abstract: The present invention provides a composite non-woven fiber material comprising at least one stainless steel fiber layer and at least one carbon fiber layer, the alternating stainless steel fiber layers and carbon fiber layers being intimately interlocked to form integrated composite material, at least one exposed surface layer of the composite material being a stainless steel fiber layer.