The plasma facing component (PFC) in nuclear fusion reactors such as divertor and first wall armors (tiles) will be always exposed to high temperature plasma of hydrogens. Therefore, heating tests should be imposed on all new materials (PFM) developed for PFC as well as usual erosion and recycling tests with hydrogens. Heating tests by electron beam irradiation and thereafter by in situ plasma discharge in JT-60 were done on new composite ceramics made of boron carbide-carbon fibers which were fabricated by hot-pressing in a vacuum at 2100°C. It is shown that the composite ceramics containing carbon fibers in curled plain fabrics (CFCPF) were not broken by the two kinds of heating test, though a composite ceramics containing one dimensional or uni-directional carbon fibers cracked in a heating test by electron beam irradiation. The composite ceramics containing CFCPF could withstand 572 shots of in situ plasma discharge in JT-60 without cracking, where NBI (neutral beam injection) heating was used with a maximum power of 30MW for 1-2s. Very small melted parts were locally formed near the edge of the tiles of the composite ceramics.
