Alumina Whiskers Formation during Self-Propagation High-Temperature Synthesis

2007 ◽  
Vol 280-283 ◽  
pp. 1021-1022 ◽  
Author(s):  
Ling Zhen Zhang ◽  
Chun Chao Zhang

In this paper, the SHS process was accomplished using titanium dioxide and aluminum powders as raw materials. It was found that the combustion process exhibited the self-spiral combustion mode and alumina whisker had formed. The morphology, microstructure and growth mechanism of alumina whisker were investigated.

2021 ◽  
Author(s):  
Chao Wang ◽  
Xiaoming Cao ◽  
Mengge Dong ◽  
Lu Zhang ◽  
Jianxing Liu ◽  
...  

<p>Self-propagating high-temperature synthesis (SHS) process is used to prepare AlB<sub>12</sub>. The phase analysis results of preparing AlB<sub>12</sub> with Al and B<sub>2</sub>O<sub>3</sub> as raw materials show that: under air and argon conditions, the self-propagating and acid-washed self-propagating powders all have α-Al<sub>2</sub>O<sub>3</sub> impurities; Mg, Al and B<sub>2</sub>O<sub>3</sub> are used as raw materials. The phase analysis results of the preparation of AlB<sub>12</sub> show that under argon conditions, the self-propagating and acid-washed self-propagating powder has unremovable MgAl<sub>2</sub>O<sub>4</sub> impurities; the root cause of the low purity of AlB<sub>12</sub> prepared by the self-propagating method is that there are unremovable impurities exist.</p>


2021 ◽  
Author(s):  
Chao Wang ◽  
Xiaoming Cao ◽  
Mengge Dong ◽  
Lu Zhang ◽  
Jianxing Liu ◽  
...  

<p>Self-propagating high-temperature synthesis (SHS) process is used to prepare AlB<sub>12</sub>. The phase analysis results of preparing AlB<sub>12</sub> with Al and B<sub>2</sub>O<sub>3</sub> as raw materials show that: under air and argon conditions, the self-propagating and acid-washed self-propagating powders all have α-Al<sub>2</sub>O<sub>3</sub> impurities; Mg, Al and B<sub>2</sub>O<sub>3</sub> are used as raw materials. The phase analysis results of the preparation of AlB<sub>12</sub> show that under argon conditions, the self-propagating and acid-washed self-propagating powder has unremovable MgAl<sub>2</sub>O<sub>4</sub> impurities; the root cause of the low purity of AlB<sub>12</sub> prepared by the self-propagating method is that there are unremovable impurities exist.</p>


2014 ◽  
Vol 525 ◽  
pp. 45-52 ◽  
Author(s):  
Xi Rui Lu ◽  
Si Jin Su ◽  
Meng Jun Chen

In order to evaluate the performance of the self-propagating high-temperature synthesis (SHS) to treat 90SrO-contained radioactive graphite in N2 atmosphere, waste forms were prepared with the self-developed SHS reactor according to the waste forms formulation designed with a solid-soluted content of 010 wt% (calibrated in mass, hereinafter the same). The waste forms were made with the exothermic reaction (3C + 4Al + 3TiO2 = 2Al2O3 + 3TiC + Q), where, 88SrO (a stable Sr isotope)-containing 88SrO was used to simulate 90SrO. And the raw materials for the waste forms were the powdery materials of graphite (C), aluminum (Al) and titanium dioxide (TiO2). Then, X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used to test and analyze the phase composition and morphology of the prepared waste forms. According to the results in dealing with the treatment with the given exothermic reaction of the 90SrOcontaining radioactive graphite in N2 atmosphere, the SrO solid solubility could be up to 8 wt%. Besides, with a SrO content of 0~2 wt%, the major composition of the waste forms was including: alumina (Al2O3) in diamond scheme, titanium carbide (TiC) in cubic phase, graphite (C), anatase titanium dioxide (TiO2) and aluminum nitride (AlN) in cubic phase. Comparatively, with a SrO content of 3~8 wt%%, the major composition of the waste forms was including: alumina (Al2O3) in diamond scheme, titanium carbide (TiC) in cubic phase, graphite (C), anatase titanium dioxide (TiO2), aluminum nitride (AlN) in cubic phase and rhomboid aluminum titanate (Al2TiO5). Furthermore, diffractive peaks of unidentified phase occurred at 2θ = 7.7°, 15.6°, 19.8° and 24.1° position, whose intensities were increased with the increasing additional SrO content. The grain sizes of the prepared waste forms are mainly within 515μm, majorly exist in pieces.


2008 ◽  
Vol 111 (2-3) ◽  
pp. 463-468 ◽  
Author(s):  
H.Y. Wang ◽  
S.J. Lü ◽  
M. Zha ◽  
S.T. Li ◽  
C. Liu ◽  
...  

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.


Author(s):  
Ю.Ю. Бачериков ◽  
И.П. Ворона ◽  
О.Б. Охрименко ◽  
В.П. Кладько ◽  
А.Г. Жук ◽  
...  

Abstract The ZnS:Mn, Mg powder is fabricated by self-propagating high-temperature synthesis with the simultaneous introduction of Mn and Mg impurities. It is found that the simultaneous introduction of Mn and Mg impurities leads to the nonuniform distribution of manganese forming regions with a lower and higher Mn concentration. In the latter case, the manganese ions form paramagnetic clusters. At the same time, numerous centers of self-activated luminescence form in the synthesized ZnS:Mn, Mg due to mechanical stress and lattice strain. Additional annealing leads to a more uniform Mn distribution in the formed ZnS:Mn, Mg phosphor, which is accompanied by an increase in the intensity of the manganese photoluminescence band and quenching of the self-activated luminescence band.


2000 ◽  
Vol 10 (8) ◽  
pp. 1925-1932 ◽  
Author(s):  
Louise Affleck ◽  
Marco D. Aguas ◽  
Ivan P. Parkin ◽  
Quentin A. Pankhurst ◽  
Maxim V. Kuznetsov

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