In situ controlled rapid growth of novel high activity TiB₂/(TiB₂-TiN) hierarchical/heterostructured nanocomposites

In this work, a reaction coupling self-propagating high-temperature synthesis (RC-SHS) method was developed for the in situ controlled synthesis of novel, high activity TiB₂/(TiB₂-TiN) hierarchical/heterostructured nanocomposites using TiO₂, Mg, B₂O₃, KBH₄ and NH₄NO₃ as raw materials. The as-synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray energy dispersive spectroscopy (EDX), transition electron microscopy (TEM), high-resolution TEM (HRTEM) and selected-area electron diffraction (SAED). The obtained TiB₂/TiN hierarchical/heterostructured nanocomposites demonstrated an average particle size of 100-500 nm, and every particle surface was covered by many multibranched, tapered nanorods with diameters in the range of 10-40 nm and lengths of 50-200 nm. In addition, the tapered nanorod presents a rough surface with abundant exposed atoms. The internal and external components of the nanorods were TiB₂ and TiN, respectively. Additionally, a thermogravimetric and differential scanning calorimetry analyzer (TG-DSC) comparison analysis indicated that the as-synthesized samples presented better chemical activity than that of commercial TiB₂ powders. Finally, the possible chemical reactions as well as the proposed growth mechanism of the TiB₂/(TiB₂-TiN) hierarchical/heterostructured nanocomposites were further discussed.