EFFECT OF BN/Ti RATIO ON THE REACTION SYNTHESIS OF TiB2-TiNx CERAMICS

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1172-1178 ◽  
Author(s):  
LEI ZHAN ◽  
PING SHEN ◽  
QI CHUAN JIANG
Keyword(s):  
High Temperature ◽  
Wave Velocity ◽  
Combustion Temperature ◽  
The Self ◽  
Molar Ratio ◽  
Reaction Synthesis ◽  
Temperature Synthesis ◽  
High Temperature Synthesis

The effects of BN / Ti molar ratio on the self-propagating high-temperature synthesis (SHS) reaction behaviors and final products in the Ti - BN system were experimentally investigated. With an increase in the BN / Ti ratio, the combustion temperature and wave velocity first increase and then decrease with the maximum values displaying at BN / Ti =0.67. A substoichiometric TiN 1- x was obtained for BN / Ti <0.67, and a stoichiometric one was produced for BN / Ti =0.67. Moreover, the microstructure photographs of the products reveal that with the increase of the BN / Ti ratio, the grains of the ceramic phases tend to be finer.

Superfast Sintering of Nanocrystalline Y2O3 Ceramics

2009 ◽  
Vol 66 ◽  
pp. 100-103 ◽  
Author(s):  
Xia Zheng ◽  
Zheng Yi Fu ◽  
Jin Yong Zhang ◽  
Wei Min Wang ◽  
Hao Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Heating Rate ◽  
Grain Growth ◽  
Combustion Temperature ◽  
Applied Pressure ◽  
The Self ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Chemical Furnace ◽  
Maximum Combustion Temperature

Dense nanocrystalline Y2O3 ceramics without grain growth have been successfully obtained by a new method, which is based on the self-propagating high temperature synthesis and quick pressing. A suitable self-propagating system with a maximum combustion temperature of 1350 °C and a heating rate of 1300 °C/min was chosen as a chemical furnace to supply the heat to densify nanocrystalline Y2O3. Dense samples without grain growth were obtained when the applied pressure was 120 MPa.

EFFECT OF Al CONTENT ON THE COMBUSTION SYNTHESIS OF (TiB2-Al2O3)/Al PRODUCTS FROM AN Al-TiO2-B2O3 SYSTEM

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3203-3208
Author(s):  
LEI ZHAN ◽  
PING SHEN ◽  
QICHUAN JIANG
Keyword(s):  
High Temperature ◽  
Delay Time ◽  
Combustion Temperature ◽  
Ignition Delay Time ◽  
The Self ◽  
Temperature Synthesis ◽  
Al Content ◽  
High Temperature Synthesis ◽  
Maximum Combustion Temperature ◽  
Opposite Tendency

The effect of Al content on the self-propagating high-temperature synthesis (SHS) reaction among Al , TiO 2 and B 2 O 3 was experimentally investigated. The Al content plays an important role in controlling the reaction behaviors. With the increase in reactant Al , the maximum combustion temperature decreases, the propagating wave velocity first increases and then decreases, while the ignition delay time shows an opposite tendency. More importantly, the increase of the Al content in the reactants has an insignificant effect on the phase constitutions of the synthesized products but reduces the size of the synthesized TiB 2 particles.

The self-propagation high-temperature synthesis of ultrafine high purity tungsten powder from scheelite

1996 ◽  
Vol 11 (7) ◽  
pp. 1825-1830 ◽  
Author(s):  
J. C. Jung ◽  
S. G. Ko ◽  
C. W. Won ◽  
S. S. Cho ◽  
B. S. Chun
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
High Purity ◽  
Tungsten Powder ◽  
The Self ◽  
Molar Ratio ◽  
Temperature Synthesis ◽  
Complete Reduction ◽  
High Temperature Synthesis ◽  
Hcl Solution

High-purity tungsten was prepared by the self-propagating high-temperature synthesis (SHS) process from a mixture of CaO · WO3 and Mg. The complete reduction of CaO · WO3 required a 33% excess of magnesium over the stoichiometric molar ratio Mg/CaO · WO3 of 3: 1. The MgO and CaO in the product were leached with an HCl solution. The product tungsten had a purity of 99.980% which was higher than that of the reactants. The high purity results because the nontungsten reactants and products are volatilized by the high temperatures generated during the rapid exothermic SHS reaction and are dissolved during HCl leaching of the product.

Phase Formation and Thermodynamic Analysis of Self-propagating High-temperature Synthesis Al–Zr–N System Composites

1998 ◽  
Vol 13 (9) ◽  
pp. 2610-2613 ◽  
Author(s):  
Kexin Chen ◽  
Changchun Ge ◽  
Jiangtao Li
Keyword(s):  
High Temperature ◽  
Melting Point ◽  
Phase Formation ◽  
Combustion Temperature ◽  
Xrd Analysis ◽  
The Self ◽  
Composite Ceramics ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
The Relationship

The self-propagating high temperature synthesis (SHS) of Al–Zr–N system composite ceramics was investigated in this paper. The melting point of Al was low (Tm = 660 °C), while that of Zr was high (Tm =1855 °C). Therefore, Al will melt and coalesce during reaction, which inhibit diffusion of nitrogen from outside the metal compact to interior due to collapse of the pore openings, while Zr will not melt under the combustion temperature which is lower than its melting point. It will not affect the permeation of nitrogen under the conditions. Accordingly, the ratio of Al and Zr in the initial mixed powders will affect the permeation of nitrogen from outside the sample to the interior, which results in different phase formation of the products. In this study, the relationship between the combustion parameters and the phase formation of the products will be experimentally determined through XRD analysis, and then thermodynamically analyzed.

Magnesium reduction of WO3 in a self-propagating high-temperature synthesis (SHS) process

1995 ◽  
Vol 10 (4) ◽  
pp. 795-797 ◽  
Author(s):  
Seog Gueon Ko ◽  
Chang Whan Won ◽  
Byong Sun Chun ◽  
H.Y. Sohn
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
High Purity ◽  
Exothermic Reaction ◽  
The Self ◽  
Molar Ratio ◽  
Temperature Synthesis ◽  
Complete Reduction ◽  
High Temperature Synthesis ◽  
Hcl Solution

High-purity tungsten was prepared by the self-propagating high-temperature synthesis (SHS) process from a mixture of WO3 and Mg. The MgO in the product was leached with an HCl solution. The complete reduction of WO3 required a 33% excess of magnesium over the stoichiometric molar ratio Mg/WO3 of 3. The product tungsten had a purity of 99.980% which was higher than that of the reactant WO3. This is because the impurities were either volatilized at the high temperatures generated during the rapid exothermic reaction or dissolved into the HCl solution during leaching.

scholarly journals Effect of Cu addition and heat treatment self-propagating high temperature synthesis reaction in Al-Ti-C system

2008 ◽  
Vol 40 (2) ◽  
pp. 207-214 ◽  
Author(s):  
Y.X. Li ◽  
J. Hu ◽  
Y.H. Liu ◽  
Z.X. Guo
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Combustion Temperature ◽  
The Self ◽  
Synthesis Reaction ◽  
Reaction Products ◽  
Temperature Synthesis ◽  
Rigid Framework ◽  
High Temperature Synthesis ◽  
Al2cu Phase

Effect of Cu addition and heat treatment on the self-propagating high temperature synthesis reaction have been investigated. The results show that Cu reacts with Al to form Al2Cu phase. With the addition of Cu, the combustion temperature of the system decreases and the porosity of the products is reduced, the size of TiC particulate decreases in the SHS reaction products. Specially, when heat treatment is carried out for the sintering products at 800 ?C, the rigid framework (sintering neck) between TiC particles was formed.

scholarly journals SHS of Oxide Systems Based on the “Mechano-Chemical” Quartz Modified by Organometallic Compounds

2016 ◽  
Vol 2 (2) ◽  
pp. 181 ◽  
Author(s):  
G.I. Ksandopulo ◽  
N.N. Mofa ◽  
T.A. Ketegenov ◽  
O.V. Cherviakova ◽  
O.A. Tyumentseva
Keyword(s):  
High Temperature ◽  
Combustion Temperature ◽  
Organometallic Compounds ◽  
The Self ◽  
Quartz Particle ◽  
Activation Time ◽  
Temperature Synthesis ◽  
Oxide Systems ◽  
High Temperature Synthesis ◽  
Material State

<p>The differences of the effects of mechanical substance pre-activation in the mills with divers force effect schemes on the self-propagating high temperature synthesis (SHS) of the SiO<sub>2</sub> + 37.5 % Al system are shown. The power saturation of activated material is determined by particle defect intensity and effects on the thermal and physical characteristics of the material. The variations of activated material state are estimated referring on the variations of dilatometry curve paths. The effects of activation time on the temperature of sample self-ignition in the furnace, combustion temperature and completeness of the quartz reaction with aluminum are determined. The enhancing effects of organic modificators of quartz particle surfaces on the further SH synthesis development are shown.</p>

Influence of Cu addition on the self-propagating high-temperature synthesis of Ti5Si3 in Cu–Ti–Si system

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

Self-propagating high-temperature synthesis microalloying of MoSi2 with Nb and V

2003 ◽  
Vol 18 (8) ◽  
pp. 1842-1848 ◽  
Author(s):  
F. Maglia ◽  
C. Milanese ◽  
U. Anselmi-Tamburini ◽  
Z. A. Munir
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Tetragonal Phase ◽  
Synthesis Method ◽  
The Self ◽  
Alloying Elements ◽  
Alloying Element ◽  
Temperature Synthesis ◽  
Starting Mixture ◽  
High Temperature Synthesis

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.

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