Abstract
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.
Highlights
Refractory materials such as borides, nitrides and carbides have attracted great attention for advanced engineering applications due to their exceptional hardness, thermal and chemical stability at high temperatures [1,2,3]
It is obvious that the samples demonstrated interesting hierarchical structures which were composed of grains and short rods
We propose an effective method for the in situ controlled, rapid synthesis of novel TiB2/(TiB2–titanium nitride (TiN)) hierarchical/heterostructured nanocomposites via the reaction coupling self-propagating high-temperature synthesis (RC-SHS) method
Summary
Refractory materials such as borides, nitrides and carbides have attracted great attention for advanced engineering applications due to their exceptional hardness, thermal and chemical stability at high temperatures [1,2,3]. When the endothermic rate was 0%, the samples presented a clear typical hexagonal prism morphology of well-crystallized TiB2 with a broad particle size of 0.02–1.5 μm (Figure 3a,b). Given the above-mentioned comparative experimental analysis results, it could be shown that the morphology, particle size, microstructure and purity of TiB2/(TiB2–TiN) samples could be effectively controlled through the in situ reaction coupling selfpropagating high-temperature synthesis (RC-SHS) method.
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