Effect of low-level boron doping on oxidation behavior of polyimide-derived carbon films

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 degrees C had a catalytic effect on the oxidation of the carbon. Based on a kinetic analysis, it is revealed that. four factors - the catalytic effect and the inhibiting effect of substitutional boron, the improvement of graphitization due to boron doping, and the formation of B2O3 during oxidation - may contribute to the appearance of the oxidation process. The catalytic effect would be dominant up to some level of carbon burn-off when less boron is doped; the contribution of the inhibiting effect(s) may rapidly become dominant when more doped boron is employed. (C) 2000 Elsevier Science Ltd. All rights reserved.