Microstructure and ablation property of C/C-ZrC-SiC composites fabricated by chemical liquid-vapor deposition combined with precursor infiltration and pyrolysis

C/C-ZrC-SiC composites were produced by the joint processes of chemical liquid-vapor deposition (CLVD) and precursor infiltration and pyrolysis (PIP), and the effects of deposition period in CLVD process on the preparation, microstructure and anti-ablation property were studied. The results displayed the non-woven layers of the composites was preferred to be densified in CLVD method, but the subsequent PIP process could fill the pores of the fiber webs. Thus the joint technologies reduced the porosity of the composites and improved the content of ceramics. Meanwhile, the insufficient deposition in CLVD process led to large amounts of defects, which were not densified fully in the following PIP. However, the excessive deposition of CLVD filled the pores remarkably, so the channels for precursor infiltration in the subsequent PIP were reduced. When the deposition period was 8 h, the sample C8P9 had a low porosity, high ceramics content and uniform distribution, which was responsible for its outstanding ablation resistance. After ablation for 60 s, sample C8P9 was damaged slightly, and its mass and linear ablation rate was 1.22 x 10(-3) g/s and 1.07 x 10(-3) mm/s. The ablation surface was divided into four regions, and the different oxide coatings were generated on these regions. These coatings could provide effective protection for the composites, which made a significant contribution to improve the ablation resistance.