Resistance to ablation of pitch-derived ZrC/C composites

Fine-grain and coarse/fine-grain pitch-derived ZrC/C composites were prepared by a hot-pressing method. Their ablation resistance was tested in an oxyacetylene flame with high velocity gas. The effects of the Zr content and the dimension of particles in the composites on the ablation were studied. Results indicated that for the fine-grain composite, a dense and uniform ZrO2 film could be formed on the substrate surface when the content of Zr was higher than 7.5%. This film could act as an effective oxygen barrier and greatly reduced the ablation rates of the composites. Although composites made up of coarse/fine particles exhibited good ablation resistance compared to pure graphite, their behavior was inferior to fine-grain composites. The ablation resistance mechanisms of ZrC/C composites were analysed using SEM microstructures and ablation models were proposed. (C) 2004 Elsevier Ltd. All rights reserved.