A novel single-source-precursor for SiC-TaC-C nanocomposites was successfully synthesized by the chemical reaction between a polycarbosilane(allylhydridopolycarbosilane,AHPCS)and tantalum(V)chloride(TaCls),which was c...A novel single-source-precursor for SiC-TaC-C nanocomposites was successfully synthesized by the chemical reaction between a polycarbosilane(allylhydridopolycarbosilane,AHPCS)and tantalum(V)chloride(TaCls),which was confirmed by Fourier transform infrared spectra(FTIR)measurement.After pyrolysis of the resultant single-source-precursors at 900"C,amorphous ceramic powders were obtained.The 900 C ceramics were anncaled at different temperatures in the range of 1200-1600℃ to gain SiC-TaC-C nanocomposites.The phase evolution of ceramic nanocomposites was investigated by X-ray diffraction(XRD)and transmission electron microscopy(TEM).The results indicate that the TaC starts to crystallize at lower temperature than theβ-SiC.It is particularly worth pointing out that the unique core-shell structured TaC-C nanoparticles were in-situ formed and homogeneously distributed in the ceramic matrix after annealing at 1400 C.Even at a high temperature of 1600 C,the grain sizes ofβ-SiC and TaC are smaller than 30 nm,flilling the definition of nanocomposites.The present study related to SiC-TaC C nanocomposites paves a new road for enriching ultra-high temperature ceramic family suitable for structural/functional applications in harsh environment.展开更多
基金Zhaoju Yu thanks the National Natural Science Foundation of China(No.51872246)for financial support.
文摘A novel single-source-precursor for SiC-TaC-C nanocomposites was successfully synthesized by the chemical reaction between a polycarbosilane(allylhydridopolycarbosilane,AHPCS)and tantalum(V)chloride(TaCls),which was confirmed by Fourier transform infrared spectra(FTIR)measurement.After pyrolysis of the resultant single-source-precursors at 900"C,amorphous ceramic powders were obtained.The 900 C ceramics were anncaled at different temperatures in the range of 1200-1600℃ to gain SiC-TaC-C nanocomposites.The phase evolution of ceramic nanocomposites was investigated by X-ray diffraction(XRD)and transmission electron microscopy(TEM).The results indicate that the TaC starts to crystallize at lower temperature than theβ-SiC.It is particularly worth pointing out that the unique core-shell structured TaC-C nanoparticles were in-situ formed and homogeneously distributed in the ceramic matrix after annealing at 1400 C.Even at a high temperature of 1600 C,the grain sizes ofβ-SiC and TaC are smaller than 30 nm,flilling the definition of nanocomposites.The present study related to SiC-TaC C nanocomposites paves a new road for enriching ultra-high temperature ceramic family suitable for structural/functional applications in harsh environment.
