scholarly journals Preparation of ZrB2-MoSi2 high oxygen resistant coating using nonequilibrium state powders by self-propagating high-temperature synthesis

2021 ◽  
Vol 10 (5) ◽  
pp. 1011-1024
Author(s):  
Menglin Zhang ◽  
Xuanru Ren ◽  
Mingcheng Zhang ◽  
Songsong Wang ◽  
Li Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Raw Materials ◽  
Nonequilibrium State ◽  
High Oxygen ◽  
Glass Layer ◽  
Composite Powders ◽  
Temperature Synthesis ◽  
Oxidation Activity ◽  
High Temperature Synthesis ◽  
Oxidation Stage

AbstractTo achieve high oxygen blocking structure of the ZrB2-MoSi2 coating applied on carbon structural material, ZrB2-MoSi2 coating was prepared by spark plasma sintering (SPS) method utilizing ZrB2-MoSi2 composite powders synthesized by self-propagating high-temperature synthesis (SHS) technique as raw materials. The oxygen blocking mechanism of the ZrB2-MoSi2 coatings at 1973 K was investigated. Compared with commercial powders, the coatings prepared by SHS powders exhibited superior density and inferior oxidation activity, which significantly heightened the structural oxygen blocking ability of the coatings in the active oxidation stage, thus characterizing higher oxidation protection efficiency. The rise of MoSi2 content facilitated the dispersion of transition metal oxide nanocrystals (5–20 nm) in the SiO2 glass layer and conduced to the increasing viscosity, thus strengthening the inerting impact of the compound glass layer in the inert oxidation stage. Nevertheless, the ZrB2-40 vol%MoSi2 coating sample prepared by SHS powders presented the lowest oxygen permeability of 0.3% and carbon loss rate of 0.29×10−6 g·cm−2·s−1. Owing to the gradient oxygen partial pressure inside the coatings, the Si-depleted layer was developed under the compound glass layer, which brought about acute oxygen erosion.

Self-Propagating High-Temperature Synthesis of Si-SiC Composite Powder

2016 ◽  
Vol 675-676 ◽  
pp. 623-626 ◽  
Author(s):  
Tawat Chanadee ◽  
Sutham Niyomwas
Keyword(s):  
High Temperature ◽  
Composite Powder ◽  
Rice Husk Ash ◽  
Argon Atmosphere ◽  
Composite Powders ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Silicon Silicon

Silicon-silicon carbide (Si-SiC) composite powders were synthesized by in-situ self- propagating high-temperature synthesis using rice husk ash (RHA)/carbon/Mg as precursors in argon atmosphere. The as-SHS powders were leached by two leaching steps. The microstructure and chemical composition of the obtained Si-SiC composite powders were examined using scanning electron microscope (SEM) and x-ray diffractometer (XRD), respectively.

The Use of Combustion Reactions for Processing Mineral Raw Materials: Metallothermy and Self-propagating High-temperature Synthesis (Review)

2015 ◽  
Vol 47 (1) ◽  
pp. 58-66 ◽  
Author(s):  
Farit Kh. Urakaev ◽  
Kenzhebek A. Akmalaev ◽  
Eljan S. Orynbekov ◽  
Beykut D. Balgysheva ◽  
Dinar N. Zharlykasimova
Keyword(s):  
High Temperature ◽  
Raw Materials ◽  
Temperature Synthesis ◽  
Mineral Raw Materials ◽  
High Temperature Synthesis

Structure and Properties of Electron-Beam Coatings, Overlaid of SHS Composite Powders "TiC – Ti", Synthesized in Air

2016 ◽  
Vol 685 ◽  
pp. 719-723 ◽  
Author(s):  
Maxim G. Krinitcyn ◽  
Gennadii A. Pribytkov ◽  
Vasiliy G. Durakov
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Structure And Properties ◽  
Composite Powders ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Different Content ◽  
Carbide Particles

A structure of Ti-TiC coatings with different content of titanium binder, overlaid of composite powders, which were obtained by self-propagating high-temperature synthesis, was investigated. The structure was studied by X-ray analysis and metallography. A size of the carbide particles in coatings, hardness of coatings and rate of wear were measured.

scholarly journals Mechanism of self-propagating hightemperature synthesis of AlB2‒Al2O3

2019 ◽  
pp. 27-36
Author(s):  
Pan Yang ◽  
Guoqing Xiao ◽  
Donghai Ding ◽  
Yun Ren ◽  
Zhongwei Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Ignition Temperature ◽  
Combustion Reaction ◽  
Peritectic Temperature ◽  
Composite Powders ◽  
Temperature Synthesis ◽  
Precipitation Mechanism ◽  
High Temperature Synthesis ◽  
Higher Temperature ◽  
Quenching Method

The mechanism of self-propagating high-temperature synthesis (SHS) of AlB2‒Al2O3 composite powders was studied by means of a combustion front quenching method (CFQM). The results showed that combustion reaction started with the melting of B2O3 and Al particles. As the combustion reaction proceeded, the interpenetration of Al and B2O3 in melts happened. The XRD results of the product revealed the reflections of Al2O3, suggesting there had been an exchange of oxygen atoms between Al and B, and evidencing the reaction, B2O3 (l) + 2Al (l) → 2B (s) + Al2O3 (l). Under higher temperature, some of B2O3 volatilized and reacted with B forming gaseous B2O2, which deposited on the surface of Al to precipitate Al2O3 and B. Then B made available dissolved into Al melt, and reacted with the Al in melt to precipitate AlB12 particles. Finally, AlB12 transforms to AlB2 at the peritectic temperature under high cooling rate. Thus, this combustion reaction can be described by the dissolution-precipitation mechanism. In the final products, besides AlB2 and Al2O3 particles, some of Al was also detected. A model corresponding to the dissolutionprecipitation mechanism was proposed, and the ignition temperature of the combustion reaction was determined to be around 800 °C. Ill. 13. Ref. 47.

scholarly journals The application of self-propagating hightemperature synthesis to obtain a protective-strengthening alumina-silica coatings

2019 ◽  
Vol 55 (2) ◽  
pp. 240-246
Author(s):  
R. Yu. Popov ◽  
E. O. Bohdan ◽  
E. M. Dyatlova ◽  
M. V. Komar
Keyword(s):  
High Temperature ◽  
Raw Materials ◽  
Operating Temperature ◽  
Thermal Unit ◽  
Ceramic Factory ◽  
Coating Structure ◽  
Temperature Synthesis ◽  
Silica Coatings ◽  
Hardening Coatings ◽  
High Temperature Synthesis

This article shows the possibility of using the method of self-propagating high-temperature synthesis to obtain protective and hardening coatings for the lining of various thermal installations. The development of compositions of ceramic masses for the production of SHS coatings was carried out on the basis of aluminum powder, clay raw materials, exhausting and fluxing components as well as mineralizing additives. The prepared suspension including pre-prepared and thoroughly mixed raw materials was applied with a brush or a spray gun onto the previously cleaned and moistened surface of an aluminosilicate refractory. The firing of the coating was carried out in accordance with the mode of removing the thermal unit at the operating temperature. The temperature of the initiation of the SHS process, previously established using differential thermal analysis, was in the range of 570–720 °C and depended on the chemical composition of the charge. It has been established that the presence of crystalline phases of silica, corundum, hematite and a number of solid solutions (mainly calcium and sodium aluminosilicates) in the coating structure provides the necessary combination of the thermomechanical and thermophysical characteristics of the coatings. On the basis of the conducted research, the expediency of applying the technology of self-propagating high-temperature synthesis for the production of protective and hardening coatings on the lining of thermal units is demonstrated, which is confirmed by industrial tests in the conditions of the Minsk Ceramic Factory OJSC «Keramin».

scholarly journals Preparation of AlB12 Powder by Self-Propagating High-Temperature Synthesis (SHS)

2021 ◽  
Author(s):  
Chao Wang ◽  
Xiaoming Cao ◽  
Mengge Dong ◽  
Lu Zhang ◽  
Jianxing Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Phase Analysis ◽  
Raw Materials ◽  
The Self ◽  
Temperature Synthesis ◽  
Root Cause ◽  
High Temperature Synthesis

<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>

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