| Summary: | In the present work, novel NbC–SiC–C ceramic nanocomposite powders were successfully synthesized by a polymer-derived ceramic approach with the allylhydridopolycarbosilane (AHPCS) and niobium pentachloride (NbCl5) as starting materials. A single-source-precursor was first synthesized by chemical reaction between AHPCS and NbCl5 and then pyrolyzed at 900 °C to obtain amorphous ceramic powders. After further annealing amorphous ceramics at higher temperatures in the range of 1100–1500 °C, the NbC–SiC–C ceramic nanocomposite powders were finally obtained. The single-source-precursor synthesis and polymer-to-ceramic transformation were characterized by Fourier transform infrared spectra (FT-IR) and thermal gravimetric analysis (TGA). The phase evolution of resulting ceramics was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Interestingly, both the NbC@C and SiC@C core−shell structured nanoparticles were in-situ formed at 1300 °C to form NbC–SiC–C ceramic nanocomposites. With the highest NbCl5 content in the feed, the contents of NbC and β-SiC obtained by Rietveld refinement of the XRD patterns from the 1500 °C ceramics are 68.41 wt.% and 31.59 wt.%, respectively, indicating that the ultra-high temperature resistant NbC is the main phase. In general, the resultant NbC–SiC–C nanocomposite with NbC as main phase can be considered as candidate material for structure−function integrated applications in harsh environment.
|
|---|