Formation and growth kinetics of ZrC layer in graphite-zirconium system

Abstract

The reaction behavior of carbon and zirconium in reactive melt infiltration (RMI) process is significantly meaningful for improvement of preparation parameters. Thus, graphite and zirconium were utilized to analyzed the microstructure, formation mechanism and growth kinetics of ZrC layer. During RMI process, continuous ZrC layer formed immediately by heterogeneous nucleation and ZrC grains grew up by solid-liquid reaction. The growth of continuous ZrC layer was governed by diffusion-reaction and dissolution-precipitation mechanism, and the former was the major factor. ZrC layer can grew to 42 μm in 5 min at 2000 °C, indicating that the porous C/C article would be filled up for a short time. The growth kinetics of ZrC layer followed a parabolic law, and the diffusion activation energy ED and effective diffusivity constant were calculated to be ∼251 kJ mol−1 and ∼0.45 × 10−6 cm2 s−1, respectively.