Effects of precursor feeding rate on the microstructure and ablation resistance of gradient C/C-ZrC-SiC composites prepared by chemical liquid-vapor deposition

Chemical liquid-vapor deposition (CLVD) is an efficient method to produce C/C composites, but rare researches about the fabrication of C/C-UHTCs composites by this process are available. Moreover, the gradient C/C-UHTCs composites have been obtained many attentions recently due to their unique microstructure and properties. Therefore, we used CLVD process to produce gradient C/C-ZrC-SiC composites and investigated the effects of precursor feeding rate on the microstructure and ablation resistance. Results displayed when the feeding rates were 30 g/h and 50 g/h, the content of ZrC decreased from the radial center to the brim while that of SiC increased, which suggested the samples had the gradient distribution. Especially, the composites prepared at the precursor feeding rate of 50 g/h had the high content of ceramics and good gradient morphology due to the excellent densification behavior. Consequently, the sample showed the low ablation rates, and the ablation center was small and shallow. However, the densification behavior of sample became bad as the precursor feeding rate increased to 70 g/h. The sample possessed the high porosity and low density, and ZrC and SiC ceramics mainly distributed in the sample brim. Thus, the sample was ablated seriously and had a deep and big ablation crater.