High thermoelectric performance of mechanically robust n-type Bi2Te3−xSex prepared by combustion synthesis

2015 ◽  
Vol 3 (12) ◽  
pp. 6603-6613 ◽  
Author(s):  
Gang Zheng ◽  
Xianli Su ◽  
Tao Liang ◽  
Qiangbing Lu ◽  
Yonggao Yan ◽  
...  
Keyword(s):  
High Temperature ◽  
Combustion Synthesis ◽  
Thermoelectric Performance ◽  
Temperature Synthesis ◽  
High Temperature Synthesis

Mechanically robust Bi2Te3-based materials with excellent thermoelectric performance are synthesized by ultra-fast self-propagating high-temperature synthesis in less than 20 min.

Effect of Mg on the Synthesis of TiB2 Powder by a Self-Propagating High-Temperature Synthesis Technique

2013 ◽  
Vol 347-350 ◽  
pp. 1144-1147
Author(s):  
Su Li ◽  
Jun Shou Li ◽  
Fang Zhao ◽  
Ming Hui Ye
Keyword(s):  
High Temperature ◽  
Combustion Synthesis ◽  
Formation Mechanism ◽  
Molar Ratio ◽  
Synthesis Reaction ◽  
Hexagonal Crystal ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Higher Temperature ◽  
Combustion Synthesis Reaction

Micro-nanoTiB2 ceramic was prepared through increasing the molar ratio of Mg and leaching with suitable acid by the combustion synthesis reaction of Mg, TiO2 and B2O3, which could get higher temperature and purer product. The Samples were investigated by XRD and SEM, and the results showed the diameter of the TiB2 was 200 nm ~ 300 nm and the shape of the TiB2 was irregular hexagonal crystal. The diameter of the TiB2 was decreased with the increase of Mg powder. The formation mechanism of TiB2 has been studied.

Reverse burning phenomenon in self-propagating high-temperature synthesis

1998 ◽  
Vol 13 (6) ◽  
pp. 1626-1630 ◽  
Author(s):  
Jou-Hong Lee ◽  
Ai-Yi Lee ◽  
Chien-Chong Chen
Keyword(s):  
High Temperature ◽  
Combustion Synthesis ◽  
External Heat ◽  
The Other ◽  
Green Density ◽  
Temperature Synthesis ◽  
Green Pellet ◽  
High Temperature Synthesis

An interesting reverse burning phenomenon was observed during the combustion synthesis of zirconium-based materials. When an external heat was applied to one end of a green pellet, the ignition was initiated at the other end. Also, the ignition position, measured from the heated end, was proportional to the apparent green density of the compact. The possible explanations for this reverse burning phenomenon are discussed.

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

2013 ◽  
Vol 16 (1) ◽  
pp. 41 ◽  
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

<p>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+6NaN<sub>3</sub>+(NH<sub>4</sub>)<sub>2</sub>SiF<sub>6</sub>+15C+Al”. In this case, the SHS product consists of four phases: silicon carbide (β-SiC) – 48.57 wt.%, α-silicon nitride (<em>α</em>-Si<sub>3</sub>N<sub>4</sub>) – 27.04 wt.%, β-silicon nitride (β-Si<sub>3</sub>N<sub>4</sub>) – 5.83 wt.%, and sodium hexafluoroaluminate (Na<sub>3</sub>AlF<sub>6</sub>) – 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 Na<sub>3</sub>AlF<sub>6</sub> playing a role a flux can be used as a modifier of castable aluminum alloys and as a reinforcing phase of aluminomatrix composites.</p>

scholarly journals Combustion Synthesis of NbB2–Spinel MgAl2O4 Composites from MgO-Added Thermite-Based Reactants with Excess Boron

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 210 ◽  
Author(s):  
Chun-Liang Yeh ◽  
Yin-Chien Chen
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Combustion Synthesis ◽  
Combustion Wave ◽  
Xrd Analysis ◽  
Activation Energies ◽  
Temperature Synthesis ◽  
Reaction Systems ◽  
High Temperature Synthesis ◽  
Spinel Mgal2o4

The formation of NbB2–MgAl2O4 composites from the MgO-added thermite-based reaction systems was investigated by self-propagating high-temperature synthesis (SHS). Two thermite mixtures, Nb2O5/B2O3/Al and Nb2O5/Al, were, respectively, adopted in Reactions (1) and (2). The XRD analysis confirmed the combination of Al2O3 with MgO to form MgAl2O4 during the SHS process and that excess boron of 30 atom.% was required to yield NbB2–MgAl2O4 composites with negligible NbB and Nb3B4. The microstructure of the composite reveals that rod-shaped MgAl2O4 crystals are closely interlocked and granular NbB2 are embedded in or scattered over MgAl2O4. With the addition of MgAl2O4, the fracture toughness (KIC) of 4.37–4.82 MPa m1/2 was obtained for the composites. The activation energies Ea = 219.5 ± 16 and 167.9 ± 13 kJ/mol for Reactions (1) and (2) were determined from combustion wave kinetics.

Modeling of wave configuration during electrically ignited combustion synthesis

2001 ◽  
Vol 16 (1) ◽  
pp. 93-100 ◽  
Author(s):  
O. A. Graeve ◽  
E. M. Carrillo-Heian ◽  
A. Feng ◽  
Z. A. Munir
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
High Temperature ◽  
Combustion Synthesis ◽  
Small Samples ◽  
Combustion Mode ◽  
Temperature Synthesis ◽  
Ignition Point ◽  
High Temperature Synthesis ◽  
Material Systems

A model was developed to study the process of current-ignited combustion synthesis. In this process, Joule heating raises the temperature to the ignition point, at which the sample reacts to form a product. Two material systems were modeled: the synthesis of SiC and MoSi2. It was found that the mode of combustion is a function of the size (radius) of the sample. The anticipated volume combustion mode was only evident in small samples. At higher values of the radius, the mode becomes wavelike (selfpropagating high-temperature synthesis) in nature. The transition from volume to wave combustion mode also depended on the properties of the material. The results are interpreted in terms of thermal conductivity and heat-transfer conditions.

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