A meltable precursor for zirconium carbide ceramics and C/C-ZrC composites

摘要

For process simplification and rapid densification of ceramic composites, a meltable single-source ZrC precursor was prepared by condensing zirconium acetylacetonate (Zr(acac)(4)) at 190 degrees C for 40-150 min. The preparation of ZrC precursor and the conversion from precursor to ceramics were investigated by using FTIR and NMR spectroscopies, GPC, DSC-TGA, XRD, SEM, EDS and TEM. The precursor had low viscosity (similar to 10 mPa s) and proper processing window (60 min) for precursor infiltration and pyrolysis (PIP). The ceramic yield at 1650 degrees C was 29.6%, and EDS revealed that the composition was (ZrC)(0.337)(HfC)(0.0025)(ZrO2)(0.044)C-0.1865. The ceramics were composed of 0.2-0.5 mu m grains which aggregated to form a stacked structure surrounded by amorphous carbon. The preparation processes were designed, and C/C-ZrC composites with the density of 2.45 g/cm(3) were successfully fabricated through 11 cycles of PIP with Zr(acac)(4). In conclusion, the synthetic method provides a simple and cheap route for precursors, and allows combined composite preparation with high efficiency.