Synthesis, Ceramic Conversion and Microstructure Analysis of TaC-SiC Ceramics by Hybrid Precursor Route

Abstract:

TaC-SiC, one member of ultrahigh-temperature ceramics (UHTCs), is potentially useful as structural materials in aerospace engineering and hypersonic flight vehicles. In this paper, the synthesis and characterization of nano-tantalopolycarbosilanes (TS) and their transformation into ceramic materials are reported. The TS-5, TS-10, TS-25, and TS-55 hybrid precursors were prepared by using nanometer tantalum powders (nano-Ta) and polycarbonsilane (PCS), according to the quality of tantalum powders and PCS at 5wt%, 10wt%, 25wt%, 55wt%, respectively, via ultrasonic and ball mill mixing method. The composition, structure, uniformity and pyrolysis process of the obtained precursors were investigated by infrared (IR), thermogravimetric (TGA), element analysis, SEM characterization, and so on. The results show that nano-Ta were dispersed uniformly in PCS. The ceramic yield of the precursors increased gradually with increase of nano-Ta proportion. The inorganic conversion was almost completed at 1073 K and TaC crystal appeared, nano-Ta was completely converted into TaC at 1673 K. As the temperature increases, the crystallization of TaC is more and more sharp, which indicates the growth of TaC grain. The non-oxygen structure, high ceramic yield, and uniform composition enable the as-received hybrid precursor as promising materials to prepare high performance ultrahigh-temperature ceramics.

Key words:UHTCs, hybrid;precursor, TaC-SiC, powders