Microstructure and ablation performance of SiC-ZrC coated C/C composites prepared by reactive melt infiltration

To improve the ablation resistance of carbon/carbon (C/C) composites, SiC-ZrC coating was prepared by reactive melt infiltration (RMI) on C/C composites. The microstructure and morphology of the coating were characterized by scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD), electron probe microanalysis (EPMA) and transmission electron microscope (TEM). The TEM specimen was fabricated by focused ions beam (FIB). The results show that the SiC-ZrC coating prepared on the condition of optimum parameter exhibits outstanding anti-ablation performance. After ablation for 60 s in oxyacetylene torch environment at heat flux of 4186 kW/m(2), the mass ablation rate (MAR) and linear ablation rate (LAR) of the coated composites were 1.18 x 10(-3)g/s and 2.47 x 10(-3) mm/s, which were 83.6% and 54.5% reduction compared with uncoated composites. During the ablation, the formed molten eutectics SiO2-ZrO2 can fill the pores and act as a diffusion barrier for oxygen and heat.