Kinetics of rapid high-temperature reactions : Titanium-nitrogen system
22 Jan 1999-Industrial & Engineering Chemistry Research (American Chemical Society)-Vol. 38, Iss: 3, pp 793-798
TL;DR: In this article, the intrinsic kinetics of reactions under conditions similar to those realized during combustion synthesis of materials were determined using a computer-assisted electrothermography method, where metal wires are heated in a reactive gas atmosphere in a controlled manner by passing electric current, and when time-dependence characteristics of electric power applied to the wire are measured, the reaction kinetics can be extracted.
Abstract: We have developed a computer-assisted electrothermography method to determine the intrinsic kinetics of reactions under conditions similar to those realized during combustion synthesis of materials. In this method, metal wires are heated in a reactive gas atmosphere in a controlled manner by passing electric current, and when time-dependence characteristics of electric power applied to the wire are measured, the reaction kinetics can be extracted. To illustrate the technique, it is applied to investigate the kinetics and other features associated with the reaction of titanium with nitrogen at 1 atm of pressure. The temperature range 1400−2300 K and heating rates 104−105 K/s are studied. It is shown that at temperatures below the melting point of titanium, the reaction follows a parabolic rate law, corresponding to a sharp-interface model with nitrogen diffusion through the developing titanium nitride layer as the rate-controlling step. The obtained activation energy value (230 kJ/mol) is in good agreement...
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TL;DR: In this article, the authors present results of their recent work both in fundamental studies of mechanisms for rapid reaction wave propagation in heterogeneous media and in using the combustion synthesis approach to synthesize different types of advanced materials, including bio-alloys and nano-sized powders.
Abstract: The combustion synthesis (CS) of materials is an advanced approach in powder metallurgy. The number of products synthesized by CS has increased rapidly during recent years and currently exceeds 1,000 different compounds. The same features, such as high temperatures and rates, self-sustained manner of microstructure formation in non-equilibrium conditions, that make CS an attractive technology also define difficulties to study the nature and mechanisms of this process, which in turn are essential to control the properties of the synthesized materials. In this survey paper, we present results of our recent work both in fundamental studies of mechanisms for rapid reaction wave propagation in heterogeneous media and in using the CS approach to synthesize different types of advanced materials, including bio-alloys and nano-sized powders.
58 citations
Cites background from "Kinetics of rapid high-temperature ..."
...Analysis of these data shows that at temperatures below the melting point of titanium (1,940 K), the reaction follows parabolic rate law, corresponding to a sharp-interface model with nitrogen diffusion through the developing titanium nitride layer as the rate controlling step [Pelekh et al., 1999]....
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TL;DR: The current state of chemical kinetics for self-propagating high-temperature non-catalytic reactions has been reviewed for results over the past 50 years in this article, where five different characterization techniques are primarily considered: differential thermal analysis, electrothermal explosion (ETE), electrothermography (ET), combustion velocity/temperature analyses (Merzhanov-Khaikin and Boddington-Laye approaches), and other advanced in-situ diagnostics, including time-resolved X-ray diffraction (TRXRD).
Abstract: The current state of chemical kinetics for self-propagating high-temperature non-catalytic reactions has been reviewed for results over the past 50 years. Five different characterization techniques are primarily considered: differential thermal analysis (DTA), electrothermal explosion (ETE), electrothermography (ET), combustion velocity/temperature analyses (Merzhanov–Khaikin and Boddington–Laye approaches), and other advanced in-situ diagnostics, including time-resolved X-ray diffraction (TRXRD). Based on the summary of results thus far, recommendations are given for the future of SHS kinetic research.
43 citations
TL;DR: In this article, a planetary ball-mill was developed to perform solid-gas reactions at constant pressure, and the influence of the nitrogen pressure on the mechanochemical reactivity of titanium powders was analyzed at 1.5 and 11 bars.
Abstract: A planetary ball-mill device that enables one to perform solid-gas reactions at constant pressure was developed. Titanium powders were ball milled under nitrogen at a spinning rate of 960 rpm. The influence of the nitrogen pressure on the mechanochemical reactivity of titanium was analyzed at 1.5 and 11 bars. A spontaneous combustion took place during the grinding process, leading to a high yield of TiN for short milling times. The conversion of titanium into titanium nitride was facilitated by increasing the nitrogen pressure. At 11 bars, full conversion was reached for grinding times shorter than 5 h. Titanium nitride obtained in this way exhibited a high sintering activity.
29 citations
TL;DR: In this paper, the influence of preheating rate on the kinetics of gasless reactions at high temperatures (above Si melting point, 1683 K) was studied using the Computer Assisted Electrothermography (CAE) method and taking the molybdenum-silicon system as an example.
Abstract: By using the Computer Assisted Electrothermography (CAE) method and taking the molybdenum-silicon system as an example, the influence of preheating rate on the kinetics of gasless reactions at high temperatures (above Si melting point, 1683 K) is studied. It is shown that an increase of heating rate Vh in the range 10–105 K/s, leads to a substantial increase in the rate of chemical reaction. At high heating rates (>103 K/s), the first stage of interaction involves rapid reaction due to the direct dissolution of Mo in the Si melt. Furthermore, the formation of MoSi2 phase, owing both to crystallization from eutectic (MoSi2-Si) melt and reaction-diffusion mechanism, is primarily responsible for the observed intensive heat release under these conditions. At lower Vh, a thin layer of Mo5Si3 phase formed at earlier stages (solid-solid interaction) significantly retards reaction at higher temperatures and changes the mechanism of interaction. Some methodological aspects of using the CAE technique for kinetic studies are also discussed. © 2004 American Institute of Chemical Engineers AIChE J, 51: 261–270, 2005
22 citations
TL;DR: In this article, the growth of thin TiN films on the TiN(0,0,1) surface during reactive sputtering was simulated by molecular dynamics with the modified embedded-atom method potential.
21 citations
References
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TL;DR: A review of the self-propagating high-temperature synthesis (SHS) method is presented in this article, which emphasizes the mechanisms of the rapid, non-isothermal reactions associated with this method.
1,002 citations
TL;DR: In this paper, an explanation of combustion (self propagating high temperature) synthesis (SHS) is given together with a historical perspective of the examination of such exothermic reactions.
800 citations
TL;DR: Combustion synthesis is an attractive technique to synthesize a wide variety of advanced materials including powders and near-net shape products of ceramics, intermetallics, composites, and functionally graded materials as discussed by the authors.
Abstract: Combustion synthesis is an attractive technique to synthesize a wide variety of advanced materials including powders and near-net shape products of ceramics, intermetallics, composites, and functionally graded materials. This method was discovered in the former Soviet Union by Merzhanov et al. (1971). The development of this technique by Merzhanov and coworkers led to the appearance of a new scientijc direction that incorporates both aspects of combustion and materials science. At about the same time, some work concerning the combustion aspects of this method was also done in the United States (Booth, 1953; Walton and Poulos, 1959; Hardt and Phung, 1973). However, the full potential of combustion synthesis in the production of advanced materials was not utilized. The scientijc and technological activity in thejeld picked up in the United States during the 1980s. The signijcant results of combustion synthesis have been described in a number of review articles (e.g., Munir and Anselmi-Tamburini, 1989; Merzhanov, I990a; Holt and Dunmead, 1991; Rice, 1991; Varma and Lebrat, 1992; Merzhanov, 1993b; Moore and Feng, 1995). At the present time, scientists and engineers in many other countries are also involved in research and further development of combustion synthesis, and interesting theoretical, experimental, and technological results have been reported from various parts of the world (see SHS Bibliography, 1996). This review article summarizes the state of the art in combustion synthesis, from both the scientijc and technological points of view. In this context, we discuss wide-ranging topics including theory, phenomenology, and mechanisms of product structure formation, as well as types and properties of product synthesized, and methods for large-scale materials production by combustion synthesis technique.
348 citations
TL;DR: In this paper, the use of thin foils to investigate the propagation of a combustion wave has been demonstrated for the nickel-aluminum system and the initiation of a reaction wave in the foils was found to be triggered by the melting of nickel regardless of the composition of the foil ensemble.
Abstract: The use of thin foils to investigate the propagation of a combustion wave has been demonstrated for the nickel‐aluminum system. The initiation of a reaction wave in the foils was found to be triggered by the melting of nickel regardless of the composition of the foil ensemble. In contrast, the propagation rate decreased with increasing nickel content in the foil ensemble. Considerable interactions, observed in advance of the combustion front, are contrary to assumptions made in existing models on the dynamics of self‐sustaining reactions. The nature and sequence of reactions between foils of Ni and Al and their relationship to the combustion front were determined.
123 citations