scholarly journals Synthesis of nanocrystalline TiB2 powder from TiO2, B2O3 and Mg reactants through microwave-assisted self-propagating high-temperature synthesis method

2016 ◽  
Vol 39 (4) ◽  
pp. 925-933 ◽  
Author(s):  
A GHANBARI ◽  
M SAKAKI ◽  
A FAEGHINIA ◽  
M SH BAFGHI ◽  
K YANAGISAWA
2003 ◽  
Vol 18 (8) ◽  
pp. 1842-1848 ◽  
Author(s):  
F. Maglia ◽  
C. Milanese ◽  
U. Anselmi-Tamburini ◽  
Z. A. Munir

Microalloying of MoSi2 to form Mo(1−x)MexSi2 (Me = Nb or V) was investigated by the self-propagating high-temperature synthesis method. With alloying element contents up to 5 at.%, a homogeneous C11b solid solution was obtained. For higher contents of alloying elements, the product contained both the C11b and the hexagonal C40 phases. The relative amount of the C40 phase increases with an increase in the content of alloying metals in the starting mixture. The alloying element content in the hexagonal C40 Mo(1−x)MexSi2 phase was nearly constant at a level of about 12 at.% for all starting compositions. In contrast, the content of the alloying elements in the tetragonal phase is considerably lower (around 4 at.%) and increases slightly as the Me content in the starting mixture is increased.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhennan Huang ◽  
Yonggang Yao ◽  
Zhenqian Pang ◽  
Yifei Yuan ◽  
Tangyuan Li ◽  
...  

AbstractDirect formation of ultra-small nanoparticles on carbon supports by rapid high temperature synthesis method offers new opportunities for scalable nanomanufacturing and the synthesis of stable multi-elemental nanoparticles. However, the underlying mechanisms affecting the dispersion and stability of nanoparticles on the supports during high temperature processing remain enigmatic. In this work, we report the observation of metallic nanoparticles formation and stabilization on carbon supports through in situ Joule heating method. We find that the formation of metallic nanoparticles is associated with the simultaneous phase transition of amorphous carbon to a highly defective turbostratic graphite (T-graphite). Molecular dynamic (MD) simulations suggest that the defective T-graphite provide numerous nucleation sites for the nanoparticles to form. Furthermore, the nanoparticles partially intercalate and take root on edge planes, leading to high binding energy on support. This interaction between nanoparticles and T-graphite substrate strengthens the anchoring and provides excellent thermal stability to the nanoparticles. These findings provide mechanistic understanding of rapid high temperature synthesis of metal nanoparticles on carbon supports and the origin of their stability.


2009 ◽  
Vol 467 (1-2) ◽  
pp. 514-523 ◽  
Author(s):  
Chyi-Ching Hwang ◽  
Cheng-Shiung Lin ◽  
Gaw-Pying Wang ◽  
Cheng-Hsiung Peng ◽  
Shyan-Lung Chung

1993 ◽  
Vol 12 (7) ◽  
pp. 500-501 ◽  
Author(s):  
M. Ohyanagi ◽  
M. Koizumi ◽  
K. Tanihata ◽  
Y. Miyamoto ◽  
0. Yamada ◽  
...  

2019 ◽  
Vol 19 (11) ◽  
pp. 7436-7441
Author(s):  
Chu Zhang ◽  
Qi-Yu Wang ◽  
Ming-De Li ◽  
Guo-Dong Zhang

Sub-micrometer particles of β-Bi2O3 were successfully synthesized via a one-step self-propagating high-temperature synthesis (SHS) method for the first time. The experiments were carried out in the air at room temperature. The products were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). In this study, three experiments were designed to optimize the heat source, Bi source and additive for the reaction system. Results showed that the system composed of Al, Bi2O3 and Al2O3 powders could synthesize monodisperse high-purity β-Bi2O3 spherical particles with the average diameter of 369 nm and the as-prepared products kept stable after being exposed in air for one month. Then, the influences of the ratio of the three components on system were investigated. Interestingly, it was found that a slight adjustment on the ratio of Al:Bi2O3:Al2O3 had significant effects on the reactions happening in a system. Specifically, when the amount of Al2O3 exceeds the molar ratio of 2:1:1 (Al:Bi2O3:Al2O3), it is difficult to ignite the reaction system; when the amount is less than 2:1:0.5, the reaction system becomes too violent to obtain pure products. However, there are no obvious differences on the morphology and structure of final products with the two ratios because of few changes in adiabatic temperature. Preparation of β-Bi2O3 by SHS technique enjoying many advantages, such as high efficiency, inexpensive experimental equipment and simple processes, would has a promising prospect for industrial application.


2010 ◽  
Vol 434-435 ◽  
pp. 116-119 ◽  
Author(s):  
Bin Li ◽  
Zong De Liu ◽  
Li Ping Zhao ◽  
Yan Rong Bao

The key problem about the application of TiC/Fe composite ceramics in high temperature is the oxidation resistance. With an aim to investigate oxidation properties, the high density TiC/Fe ceramics was produced by self-propagating high-temperature synthesis method combined with pseudo hot iso-static pressing (SHS/PHIP). The oxidation kinetics of TiC/Fe ceramics were investigated by means of conducting the isothermal oxidation experiments in air at temperature of 550°C  900°C for up to 150 hours, and measuring the variations of the weight gains of the composites with the oxidation times. The microstructure evolution of the composites during the oxidation processing was studied by using SEM/EDS and XRD. Experimental results show that TiC/Fe ceramics basically follows a parabolic rule at high temperature. A detailed characterization of the microstructure and distribution of the phases within the scale following oxidation studies has been undertaken to suggest the possible mechanism for the oxidation of TiC/Fe ceramics.


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