Gradient nanoporous structures based on silicon carbide and boron nitride in self-propagating high-temperature synthesis

High-quality boron nitride nanotubes were synthesized by annealing porous precursor in flowing NH3gas at 1150°C. The porous precursor B18Ca2(MgO)9was produced by self-propagation high-temperature synthesis (SHS) method using Mg, B2O3, and CaB6as the starting materials, which played an important role in synthesis of BN nanotubes in large quantities. Samples were characterized by SEM, TEM, EDX, HRTEM, X-ray powder diffraction (XRD), Raman, and Fourier transform infrared (FTIR) spectroscopy. The as-synthesized BN nanotubes have an average diameter of about 150 nm with a wall/diameter ratio of 2/3. Mean length of the BN nanotubes was more than 10 μm. The effects of temperature, time, and the possible mechanism of the growth of the BN nanotubes were also discussed.

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Obtaining the Nanostructured Nitride Composition TiN-BN Powder by the Self-Propagating High-Temperature Synthesis from the Azide KBF4-NaN3-Na2TiF6 and "NH4BF4-NaN3-Na2TiF6 Systems

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.698.507 ◽

2014 ◽

Vol 698 ◽

pp. 507-512

Author(s):

Irina Kerson ◽

Ljudmila Shiganova

Keyword(s):

High Temperature ◽

Boron Nitride ◽

Sodium Azide ◽

Composite Powder ◽

The Self ◽

Nanosized Powder ◽

Temperature Synthesis ◽

High Temperature Synthesis ◽

Halide System ◽

One Step

This paper presents the results of a study on the preparation of nanostructured nitride composition TiN-BN in the boron halide - sodium azide - titanium halide system by the azide SHS technology. SHS-Az technology makes it possible to produce powders having the desired properties, only in one step, without blending separately prepared powders of titanium nitride and boron nitride, and to obtain the final product in the form of micro-and nanosized powder nitride compositions TiN-BN by using complex halides of titanium and boron. Thus, the composite powder TiN and BN obtained from the KBF4-NaN3-Na2TiF6» and «NH4BF4-NaN3-Na2TiF6 systems can be classified as a nanostructured powder (nanopowder).

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Effect of additives on the properties of silicon carbide-based refractories obtained by self-propagating high-temperature synthesis (SHS)

Refractories and Industrial Ceramics ◽

10.1007/bf02768229 ◽

1997 ◽

Vol 38 (1) ◽

pp. 21-22

Author(s):

T. A. Boiko ◽

A. B. Ivanov ◽

Z. V. Tret’yakova

Keyword(s):

Silicon Carbide ◽

High Temperature ◽

Temperature Synthesis ◽

Effect Of Additives ◽

High Temperature Synthesis

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Self-Propagating High-Temperature Synthesis of Silicon Carbide and Silicon Nitride Nanopowders Composition using Sodium Azide and Halides

Eurasian Chemico-Technological Journal ◽

10.18321/ectj167 ◽

2013 ◽

Vol 16 (1) ◽

pp. 41 ◽

Cited By ~ 2

Author(s):

Yu.V. Titova ◽

A.P. Amosov ◽

G.V. Bichurov ◽

D.A. Maidan

Keyword(s):

Silicon Carbide ◽

High Temperature ◽

Silicon Nitride ◽

Combustion Synthesis ◽

Sodium Azide ◽

Average Particle Size ◽

Average Particle ◽

Temperature Synthesis ◽

High Temperature Synthesis ◽

Working Volume

Regularities of self-propagating high-temperature synthesis (SHS) or combustion synthesis (CS) by using “silicon – sodium azide – ammonium hexafluorosilicate – carbon – aluminum” powder mixture in the nitrogen atmosphere were investigated. The thermodynamic analysis of the combustion synthesis was performed. Experimental investigation of the combustion process: the measurement of linear rates of the combustion front propagation and the maximum combustion temperatures was conducted in a laboratory reactor with working volume 4.5 liters. The influence of the components ratio in the initial mixture on the combustion temperature, combustion rate and composition of reaction product was studied. The phase composition of the product synthesized was determined with an X-ray diffractometer. It was disclosed that the SHS product consists of the composition (mixture) of silicon carbide nanopowder with silicon nitride whiskers and a final halide. Investigation of surface topography and morphology of the product particles was carried out with a scanning electron microscope. Optimal mixture for the synthesis of nanoscale composition based on silicon carbide was determined: “14Si+6NaN3+(NH4)2SiF6+15C+Al”. In this case, the SHS product consists of four phases: silicon carbide (β-SiC) – 48.57 wt.%, α-silicon nitride (α-Si3N4) – 27.04 wt.%, β-silicon nitride (β-Si3N4) – 5.83 wt.%, and sodium hexafluoroaluminate (Na3AlF6) – 18.56 wt.%. The average particle size of the composition was in the range of 70–130 nm. It was shown that the composition of the silicon carbide with silicon nitride and the final halide Na3AlF6 playing a role a flux can be used as a modifier of castable aluminum alloys and as a reinforcing phase of aluminomatrix composites.

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