Abstract: In this test,three kinds of carbon/carbon composites with short fiber resin molded,carbon cloth laminated construction and woven fabric preform architecture are prepared using CVD technology.The oxidation behaviors of the three kinds of carbon/carbon composites are investigated,and the oxidation kinetics data are calculated.The results show that when the weight lost is less than 60%,the relationship between the weight lost rate and oxidation time show a clear linear behavior,and the three kinds of composites have different apparent activation energies at about 700 ℃,leading to the different domination mechanisms:the oxidation rates are controlled by the kinetics under 700 ℃,and dominated by diffusion over 700 ℃.The oxidation rates lie on the preform architecture due to different perform architectures forming different pyrolytic carbons,and the carbon cloth/CVD composite has a lower oxidation resistance capability than the others.The oxidation processes of three kinds of carbon/carbon composites are accordant on the whole,and the oxidation first takes place at the lacuna of the matrix,going with both the carbon fibers and the matrix carbon being oxidated at the same time.With progressive oxidation,the carbon fibers become more and more thin,and the matrix carbon leaves a very filmy bed only,some matrix carbons fall off from the fibers or some terribly asymmetric and porous matrix carbons are around the fibers.

Key words: C/C composites, oxidation behavior, preform architecture