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PMDA-ODA (pyromellitic dianhydride-4,4'-oxydianiline) polyimide (PI) films with thickness of 2-26 μm were synthesized and heat-treated at 2200-2500 o C. The effect of film thickness on both the graphitizability of the PI-derived carbon film and the crystalline organization of the initial PI film was investigated by X-ray diffraction. The degree of graphitization of the resultant carbon film...
The oxidation behavior of polyimide-derived carbon films doped with boron in low levels (up to 1.23x10 -2 B/C) was investigated by means of thermogravimetric analysis (TGA). It was observed that boron-doping less than 7.09x10 -3 B/C in the carbon film formed at 1500 o C had a catalytic effect on the oxidation of the carbon. Based on a kinetic analysis, it is revealed...
C–SiC–B 4 C composite materials were fabricated from pitch based needle coke, SiC and B 4 C with or without SiC nanoparticulate additive by grinding and then pressureless sintering. Anisothermal and isothermal oxidation tests of the composites obtained were carried out in oxygen flow at temperature increasing continuously from 773 to 1573K. Self-protection behavior of the composites...
The decarbonization and oxidation processes in ceramic-carbon composites during oxidation in gaseous oxygen have been studied theoretically. The influences of temperature, duration of time, content of ceramic in the composites and other factors on the oxidation are discussed kinetically. According to the model, the recession rate of the carbon matrix will slow down rapidly with decrease of ceramic...
Preparation of dense carbon materials without use of any binder was attempted, effect of grinding treatment on the characteristics of raw petroleum needle coke and on the properties of the sintered carbon compacts was investigated, and the sintering mechanizm of the coke after grinding was discussed. It was found that the coke particle size and crystalline size was decreased and the specific surface...
The formation and oxidation resistance of surface oxide layers formed on carbon-B 4 C-SiC composites with two different B 4 C-SiC ratios were investigated at elevated temperatures in dry and moist atmospheres. From SEM observation, X-ray diffraction analysis, EPMA, and ESCA measurements of the samples before and after oxidation, it was found that the oxidation resistance depended...
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