High-temperature diffusion behavior of ZrC in C matrix and its promotion on graphitization
(1. State Key Laboratory of New Ceramics & Fine Processing, School of Materials Science and Engineering,
Tsinghua University, Beijing 100084, China;
2. Science and Technology on Advanced Functional Composites Laboratory,
Aerospace Research Institute of Materials and Processing Technology, Beijing 100076, China;
3. Research Center of Nano Science and Technology, Advanced Material Composite and Dispersion Technology Engineering Research Center of Ministry of Education of China, Shanghai University, Shanghai 200444, China)
Tsinghua University, Beijing 100084, China;
2. Science and Technology on Advanced Functional Composites Laboratory,
Aerospace Research Institute of Materials and Processing Technology, Beijing 100076, China;
3. Research Center of Nano Science and Technology, Advanced Material Composite and Dispersion Technology Engineering Research Center of Ministry of Education of China, Shanghai University, Shanghai 200444, China)
Abstract: C/C composite material is widely used in aerospace field and others, however, it is easy to be oxidized at high temperature. In order to improve the oxidation resistance, ZrC is introduced as an oxidation inhibitor used in matrix modification of C/C composite material. Flat plate samples of ZrC/C composite materials were prepared by hot-pressing sintering. The degree of graphitization increases with rising sintering temperature, and layer structure of carbon matrix is observed clearly in the sample treated at 2273 K. Diffusion behavior of Zr in C matrix at high temperature is studied, which can be generally expressed as D=3.382×10-11 exp[2.029×105/(RT)]. The diffusion of Zr in C matrix leads to the over-saturation of C in the micro area and the oversaturated C precipitates as graphite. This continuous process promotes the transformation of carbon to graphite.
Key words: ZrC; carbon material; diffusion; graphitization