Preparation and Microstructure Characterizations of Novel C/C-Zr(Hf)B₂-Zr(Hf)C-SiC Composites

Abstract:

A series of novel C/C-Zr (Hf)B₂-Zr (Hf)C-SiC composites were prepared by chemical vapor infiltration (CVI) of pyrolytic carbon and polymeric impregnation and pyrolysis (PIP) with hybrid polymeric precursors of SiC (polycarbosilane), Zr (Hf)C and Zr (Hf)B₂ in carbon fiber preforms. The formed ultra-high temperature ceramics (UHTCs) matrix of SiC-ZrC-ZrB₂ and SiC-HfC-HfB₂ were designed to improve the oxidation resistance of carbon/carbon composite at very high temperatures above 2000°C. The pyrolysis process of Zr (Hf)C and Zr (Hf)B₂ polymeric precursors was investigated, and the results showed that the hybrid precursors could be successfully transformed into Zr (Hf)C and Zr (Hf)B₂ ceramic particles with the sizes of nanometer with temperatures above 1500°C. Furthermore, the multiscale structure of C/C-Zr (Hf)B₂-Zr (Hf)C-SiC composites were also characterized , showing that the carbon fibers were covered by pyrolytic carbon, and the continuous ceramic matrix was well dispersed, formed by Zr (Hf)C and Zr (Hf)B₂ nanoparticles distributing homogeneously in the continuous SiC matrix. This homogeneous dispersion of composite ceramics of Zr (Hf)C and Zr (Hf)B₂ with SiC plays excellent protection of C/C composites from oxidation at high temperature via formation of stable oxides coatings.

• Periodical: Materials Science Forum (Volume 788)
• Pages: 593-597
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.788.593
• Online since: April 2014
• Authors: Jie Wen Li, Xi Wei, Wei Gang Zhang*, Min Ge
• Keywords: C/C-Zr (Hf)B₂-Zr (Hf)C-SiC Composites, Hybrid Precursors, Polymeric Impregnation, Pyrolysis

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