Abstract
Mechanochemical synthesis (MCS) investigations of niobium silicide powders in Nb 2 O 5 –]SiO 2 –]Mg powder mixtures were conducted via high-energy ball milling and leaching by means of process parameters such as the milling duration, initial Nb 2 O 5 crystal structure, and excess Mg amount. The compositional, thermal, and microstructural properties of the products were characterised using X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), particle size analysis (PSA), stereomicroscopy (SM), scanning electron microscopy (SEM), and transmission electron microscopy/energy-dispersive spectrometry (TEM/EDS). After the 5 h milling of the stoichiometric mixtures, an instantaneous ignition occurred and NbSi 2 , Nb 5 Si 3 , Nb, and MgO phases formed with some residual Mg. In addition, the use of excess Mg inhibited the formation of Nb 5 Si 3 . Afterwards, leaching treatments (in a 4 M HCl solution) completely removed the Mg-based phases from the synthesised products. The XRD calculations revealed that the resultant product consisted of 97 wt% NbSi 2 and 3 wt% Nb 5 Si 3 phases. The TEM analyses indicated that each Nb silicide nanoparticle was coated with a SiO 2 layer. According to random measurements, the average particle size of the Nb silicide cores and average thickness of the SiO 2 layer were approximately 61 and 7.5 nm, respectively.
Original language | English |
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Pages (from-to) | 10654-10663 |
Number of pages | 10 |
Journal | Ceramics International |
Volume | 45 |
Issue number | 8 |
DOIs | |
Publication status | Published - 1 Jun 2019 |
Bibliographical note
Publisher Copyright:© 2019 Elsevier Ltd and Techna Group S.r.l.
Keywords
- Electron microscopy
- Powders: solid state reaction
- Silicides
- Transition metal oxides