Oxidation behaviour of matrix-modified carbon-carbon composites at high temperature

The approach of matrix modification has been used to increase the high-temperature oxidation resistance of carbon-carbon composites. A distinct effect has been obtained, and the oxidation law of matrix-modified composites at high temperature has been investigated. Initially, the change in weight loss with oxidation time for matrix-modified carbon-carbon composites at constant temperature was studied. The results show that the oxidation process can be divided into three stages: a linear stage (1) with the weight loss increasing from 0 to 60%, an exponential stage (2) with weight losses between 60% and 80%, and a linear stage (3) with weight losses from 80% to 100%. Also, the variation of weight loss with oxidation temperature for matrix-modified carbon-carbon composites at constant oxidation time was measured. The results showed that this variation could be divided into three stages: a constant weight stage from ambient temperature to the temperature of initial weight loss, an exponential stage from the commencement of initial weight loss to a residual weight of about 70%, and a linear stage as the residual weight falls from 70% to 0. A mathematical theory for the three stages has been derived and tested. This treatment may prove useful for improving the high-temperature oxidation resistance of carbon-carbon composites and their properties in service.