THE FRACTURE MECHANISM OF CARBON/CARBON COMPOSITES WITH THE DIFFERENT HEATTREATMENTS AT ITS INITIAL STAGE OF OXIDATION

摘要

Although studies have been made on the oxidation behavior of Carbon/Carbon composites, littlernis known about the oxidation behavior and fracture mechanism of Carbon/Carbon composites with therndifferent heat-treatments at initial stage of oxidation. In this study, oxidation behaviors of Carbon/Carbonrncomposites with the different heat-treatment temperature were investigated at high temperature in air byrnmeasuring weight loss with oxidizing time. I would like to focus on fracture mechanism of variou types ofrnCarbon/Carbon composites at the initial stage of oxidation. As a result, at the initial stage of oxidation, thernoxidation degradation of Carbon/Carbon composites were recognized at the boundaries at fiber/matrixrninterface. We consider that these have amorphous structure, and these structures of fiber/matrix interfacerndifferent heat-treated temperature. The oxidation degradation initiated from amorphous structure at therninitial stage. The reduction of shear strength were preferentially recognized in the case of specimenrnoxidized at 600℃ comparing to the oxidized at 1000℃ , even when the total weight loss is almost thernsame. The larger changes inner part structures by oxidation, the more decrease the strength ofrnCarbon/Carbon composites.