Showing papers in "International Journal of Self-propagating High-temperature Synthesis in 2017"
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: Solution combustion synthesis (SCS) is a preparation technique that can be used to synthesize a variety of inorganic nanomaterials and structured catalysts as mentioned in this paper, which is based on a self-propagating exothermic redox reaction between organic salts and a fuel mixed together in an aqueous solution.
Abstract: Solution combustion synthesis (SCS) is a preparation technique that can be used to synthesize a variety of inorganic nanomaterials and structured catalysts. It is based on a self-propagating exothermic redox reaction between organic salts and a fuel mixed together in an aqueous solution, which results in the formation of nanocrystalline and highly pure solid nanomaterials. SCS can be considered as an attractive synthesis method for catalysts due to the simple nature of the synthetic route and short reaction times. The process is easily scaled up to any kind of application which makes it economically attractive. This mini-review provides a short overview on the synthesis of structured catalysts by SCS and their recent utilization for energy applications and pollution control.
39 citations
TL;DR: In this article, a brief review discusses principles and some latest developments in electrically activated combustion synthesis, including FACS, FAPAS, reactive spark plasma sintering (R-SPS), electrothermal explosion (ETE), and electrostatic-field-activated combustion synthesis (EFACS).
Abstract: This brief review discusses principles and some latest developments in electrically activated combustion synthesis. Processes discussed include field-activated combustion synthesis (FACS), field-activated pressure-assisted synthesis (FAPAS), reactive spark plasma sintering (R-SPS), electrothermal explosion (ETE), and electrostatic-field-activated combustion synthesis (EFACS). These processes have demonstrated clear benefits to the process of combustion synthesis through the application of electric field. Although a significant amount of works have been published in the area, there still remain some directions within the field where sustained research may provide even more scientific reward.
27 citations
TL;DR: In this paper, the FTIR spectra of synthesized ferrites showed two absorption bands (ν1 and ν2) in the range 400-600 cm-1 belonging to tetrahedral and octahedral interstitial sites in the spinel lattice.
Abstract: Solid solutions Ni0.5–xCdxZn0.5Fe2O4 (x = 0, 0.15, 0.30) were prepared by solid-state synthesis and characterized by FTIR spectroscopy. The FTIR spectra of synthesized ferrites showed two absorption bands (ν1 and ν2) in the range 400–600 cm–1 belonging to tetrahedral (A) and octahedral (B) interstitial sites in the spinel lattice. The force constants for tetrahedral (Kt) and octahedral sites (Ko) were determined, as well as Young’s modulus (E), rigidity modulus (G), bulk modulus (B), Debye temperature (ΘD), and velocity of transverse (Vt) and longitudinal (Vl) elastic waves. The relevant interionic cation–anion, cation–cation distances and bond angles are also reported.
22 citations
17 citations
TL;DR: In this article, a solution-combustion synthesis (SCS) of MZrO3 zirconates (M = Ca, Sr, Ba) in an open reactor with glycine as a fuel was studied both experimentally and theoretically.
Abstract: Solution-combustion synthesis (SCS) of MZrO3 zirconates (M = Ca, Sr, Ba) in an open reactor with glycine as a fuel was studied both experimentally and theoretically. Calculated thermal effects of the above SCS reactions were found to reasonably agree with experiment. The measured thermal effects of SCS reactions (ΔT
max) as a function of fuel/oxidant ratio (φ) exhibited a maximum within the range φ = 0.9–1.3 arising due to increasingly growing radiative heat loss from the open surface of burning reactive mixture. The occurrence of self-sustained SCS reactions yielding CaZrO3, SrZrO3, and BaZrO3 was found possible for φ ≥ 0.4, 0.3, and 0.4, respectively.
11 citations
TL;DR: Microwave heating fundamentally differs from other heating techniques as the consequence of its unique characteristic of being based on the electromagnetic energy transfer from the microwaves source to the interacting material, which according to its electric, dielectric, and magnetic properties can convert the absorbed energy into heat as mentioned in this paper.
Abstract: Microwave heating fundamentally differs from other heating techniques as the consequence of its unique characteristic of being based on the electromagnetic energy transfer from the microwaves source to the interacting material, which according to its electric, dielectric, and magnetic properties can convert the absorbed energy into heat. This peculiar heating mechanism is at the basis of plenty of unquestionable advantages that were reported during the last three decades in most of the different branches of chemistry as well as materials science, thus including also combustion synthesis. After a brief overview of the microwave heating fundamentals as well as of the different components constituting the scientific microwave applicators, all the most significant and recent advancements in the use of microwaves as energy source in both solid-state as well as solution combustion synthesis processes will be comprehensively reviewed, highlighting the unique opportunities arising from the coupling of these two energy efficient techniques. Moreover the possible employment of less conventional frequencies as well as the use of new-generation solid state generators will be critically discussed also in the framework of scaling-up and microwave reactor design considerations.
10 citations
TL;DR: In this paper, a mini-review aims at summarizing the recent data on the solution-combustion synthesis of nano-structured anode and cathode materials for lithium-ion batteries.
Abstract: Solution-combustion synthesis (SCS) is an effective method for mass production of electrode materials, in particular metal oxides, for electrochemical energy storage owing to its simplicity and energy/time effectiveness The present mini-review aims at summarizing the recent data on the SCS of nano-structured anode and cathode materials for lithium-ion batteries The advantages of electrode materials prepared by SCS are discussed in detail, with special emphasis on morphology control during the SCS process
9 citations
TL;DR: In this article, the microstructure and chemical composition of synthesized ferrites were characterized by SEM, EDS, and XRD, and the equilibrium composition of reacting compounds was calculated using a standard Gibbs energy minimization approach.
Abstract: Nickel-ferrite magnetic materials were synthesized by in-situ combustion synthesis from Fe2O3–Fe–NiO powder mixtures in air. The equilibrium composition of reacting compounds was calculated by using a standard Gibbs energy minimization approach. The microstructure and chemical composition of synthesized ferrites was characterized by SEM, EDS, and XRD.
9 citations
TL;DR: Azide SHS technology with NaN3 powder as a nitriding agent was used to fabricate TiN, AlN-BN, and Si3N4-TiN nanopowders.
Abstract: Azide SHS technology with NaN3 powder as a nitriding agent was used to fabricate TiN–BN, AlN–BN, and Si3N4–TiN nanopowders using Nа2TiF6, (NH4)2TiF6, KBF4, NH4BF4, Nа3AlF6, AlF3, Na2SiF6, and (NH4)2SiF6 as precursors. Mixtures of the above salts with sodium azide NaN3 readily burned in an SHS reactor to yield agglomerated nanosized or fine target powders. Phase composition of combustion products not always corresponded to expectations and often contained insoluble byproducts. Reported are optimal green compositions and procedures that afford the preparation of target TiN–BN, AlN–BN, and Si3N4–TiN nanopowders free of byproducts.
7 citations
TL;DR: In this article, a mixture of actinide-Zr-RE-containing high-level nuclear wastes (HLW) was modeled by a mixture consisting of CeO2, La2O3, ZrO2 and MnO2 powders.
Abstract: Mineral-like Y2(Ti1–x
Zr
x
)2O7 ceramic matrices for immobilization of actinide–Zr–RE-containing high-level nuclear wastes (HLW) were prepared by SHS method. In experiments, HLW were modeled by a mixture of CeO2, La2O3, ZrO2, MnO2, and Fe2O3 powders. An increase in the HLW content of green mixture decreased the amount of Y2(Ti1–x
Zr
x
)2O7 in combustion product and increased that of ZrO2, LaTiO3, and CaTiO3; decreased the fractional substitutionality of Zr for Ti; and increased the product porosity. An increase in combustion temperature and suppression of heat sink during SHS reaction did not diminish markedly the porosity of synthesized ceramics.
TL;DR: Magnesium ferrite (MgFe2O4) was prepared by simple low-cost oxalate coprecipitation method and characterized by XRD and SEM as mentioned in this paper, which revealed a non-uniform morphology and some certain extent of agglomeration.
Abstract: Magnesium ferrite (MgFe2O4) was prepared by simple low-cost oxalate coprecipitation method and characterized by XRD and SEM. The X-ray analysis confirmed the formation of a single-phase cubic spinel structure. The product revealed a non-uniform morphology and some certain extent of agglomeration. Crystallite size, texture coefficient, dislocation density, hopping length, and mechanical properties of the product are also reported.
TL;DR: In this paper, the authors found that NiAlNb composite containing NiAl, NiAl Nb, and trace amounts of Nb5Ni and good joining with a transition zone.
Abstract: Thermal explosion in (Ni + Al)/Nb/(Ni + Al + Nb) sandwiches was found to results in formation of (a) NiAlNb composite containing NiAl, NiAlNb, and trace amounts of Nb5Ni and (b) good joining with a transition zone.
TL;DR: In this paper, the influence of thermal treatment in vacuum (TTV) on combustion of Ti-B powder mixtures was explored, and the authors used commercially available powders of Ti (PTOM brand) and amorphous boron (B-99А brand, m.p. 2076°C).
Abstract: In this work, we explored the influence of thermal treatment in vacuum (TTV) on combustion of Ti–B powder mixtures. In our experiments, we used commercially available powders of Ti (PTOM brand) and amorphous boron (B-99А brand, m.p. 2076°C). Amounts of impurity hydrogen in Ti powder were determined by using the TTV procedure similar to that described in [1]: a weighed amount of Ti powder was placed into an evacuated silica tube (7.5 · 10–3 torr) and held at 850°C for 2 h.
TL;DR: In this article, Pd-Ag nanoparticles with different Pd/Ag ratio were deposited onto fiber glass by using the technique of surface self-propagating thermal synthesis (SSTS).
Abstract: Pd–Ag nanoparticles with different Pd/Ag ratio were deposited onto fiber glass by using the technique of surface self-propagating thermal synthesis (SSTS) and characterized by X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (ААS), and EXAFS spectroscopy. The samples reduced in hydrogen exhibited the formation of Pd–Ag alloy whose tentative structure and composition were suggested. Thermally scheduled reduction of Pd–Ag catalysts in hydrogen made the Ag atoms partially oxidized. Reported are the catalytic properties of synthesized Pd–Ag samples in selective hydrogenation of acetylene.
TL;DR: In this article, the ignition, combustion, and detonation of Teflon-W mixtures containing Al as a booster was studied. But the results of the experiments were limited.
Abstract: Teflon–metal mixtures are widely used in pyrotechnics as blasting compositions (Teflon–Mg mixtures) [1], inhibitors of combustion [2], and thermal traps in helicopters and aircrafts. Explosive processing of metal–polymer composites is used to fabricate structural, antifriction, heat-insulating, and soundproof materials [3]. In some cases, heat-generating composites must have high specific gravity which can be attained in the presence of heavy-weight metals such as W. In contrast to well documented reactions of Teflon with Al and Mg [4], the ignition, combustion, and detonation of Teflon–W mixtures practically have not been studied so far. In this communication we fill this gap and report our recent results on the ignition of Teflon–W mixtures containing Al as a booster.
TL;DR: In this article, the SHS waves in multilayer Ni/Al nanofilms and the explosive crystallization waves in Sb films were comparatively explored by IR imaging and SEM.
Abstract: The SHS waves in multilayer Ni/Al nanofilms and the explosive crystallization waves in Sb films deposited onto a thin copper substrate were comparatively explored by IR imaging and SEM. Despite a markedly lower thermal effect of crystallization, the waves of chemical reaction and crystallization were found to have much in common in their temperature–time histories: warmup rate, temperature gradient in the wave front, and duration of heat release. Observed was a micro-scintillation mode of the propagation of explosive crystallization wave in Sb films.
TL;DR: In this paper, a low-temperature combustion synthesis of Yttrium aluminum garnet (Y3Al5O12, YAG) with different fuels such as urea, glycine, and ammonium acetate was studied.
Abstract: Yttrium aluminum garnet (Y3Al5O12, YAG) was synthesized by low-temperature combustion synthesis (CS) with different fuels such as urea, glycine, and ammonium acetate. It has been observed that combination of urea and glycine fuels results in the formation of YAG with some impurity phase. The effect of Si incorporation in the process was studied. The combustion synthesis from mixed fuels and silica was found superior for low-temperature synthesis of pure YAG at without further heat treatment. Phase evolutions and results of flame temperature measurements are reported. Rietveld refinement and analytical calculation of different structural parameters were performed to get proper notion about Si substitution in host matrix. The thermoluminescence (TL) of materials caused by UV irradiation was used to elucidate the nature of traps. The TL analysis revealed the presence of shallow traps whose amount grew with Si doping.
TL;DR: In this article, a cast ceramic composites were prepared by metallothermic SHS under elevated Ar pressure (5 MPa), where variations in green composition were used to affect the phase composition of combustion products.
Abstract: Cast ceramic composites were prepared by metallothermic SHS under elevated Ar pressure (5 MPa). Variation in green composition was used to affect the phase composition of combustion products. Under some optimized conditions, resultant ceramics can be obtained in the form of Al2O3–Cr2O3 solid solutions, Al2O3–Cr2O3 ∙ хZrO2 composites or single-phase Al2MgO4. Such materials seem promising for use in jewelry, process engineering (casting molds, cutting tools), and aerospace industry.
TL;DR: In this paper, a high pressure of nitrogen gas in the presence of heat-generating agent, Mg(ClO4)2, as a booster was used to synthesize low-caloric aluminum oxynitride (γ-AlON) powders.
Abstract: Aluminum oxynitride (γ-AlON) powders were prepared from low-caloric Al–Al2O3 mixtures by SHS under high pressure of nitrogen gas in the presence of heat-generating agent, Mg(ClO4)2, as a booster. The preparation procedure was characterized and optimized with respect to Al/Al2O3 ratio, amount of heatgenerating additive, and nitrogen gas pressure. The morphology of synthesized γ-AlON powders was found to depend on Al powder brand. Compared to γ-AlON powders obtained in chemical furnace, we managed to prepare less sintered arenaceous cakes that could be easily disintegrated into target γ-AlON powder. SHSproduced powders may find their application in production of optical ceramics.
TL;DR: The current issue of International Journal of Self-Propagating High-Temperature Synthesis is dedicated to the 50th anniversary of the solid flame discovery, by A.G. Merzhanov, V.M. Shkiro and I.P. Borovinskaya in 1967, which led to the development of rapid synthesis methods based on exothermic reactions in condensed systems as mentioned in this paper.
Abstract: The current issue of International Journal of Self-Propagating High-Temperature Synthesis is dedicated to the 50th anniversary of the ‘solid flame’ discovery, by A.G. Merzhanov, V.M. Shkiro, and I.P. Borovinskaya in 1967, which led to the development of rapid synthesis methods based on exothermic reactions in condensed systems. Today, Self-propagating High-temperature Synthesis (SHS) and Solution Combustion Synthesis (SCS) are very popular preparation techniques for numerous simple and complex compounds including oxygen-free ceramics, oxides, chalcogenides, metals, alloys, and composites in the form of nanoscale powders, porous items, thin films, etc. The present issue consists of brief topical review articles by active researchers in the field. The articles cover principles and some recent developments in SHS and SCS.
TL;DR: In this article, it was shown that the formation of single-phase NbSi2 from strictly stoichiometric Nb-2Si mixtures by mechanoactivated SHS (MA SHS) cannot be achieved because of sticking milled material to the surface of milling bodies.
Abstract: Influence of MA on combustion in Nb–2Si mixtures has been studied by us recently [14]. It has also been found [15, 16] that the formation of single-phase NbSi2 from strictly stoichiometric Nb–2Si mixtures by mechanoactivated SHS (MA SHS) cannot be achieved because of sticking milled material to the surface of milling bodies. Other methods for preparation of niobium silicides – metallothermic reactions, fieldassisted SHS, long-term mechanical alloying [17–19] – seem to be energyand time-consuming.
TL;DR: In this paper, the SHS method was applied to create hierarchical structured porous hollow carbon nanospheres, mesoporous carbon nanosheets, and AlN stellar and multi-storey dendrite microcrystals.
Abstract: We applied SHS method (also known as combustion synthesis) to create hierarchically structured porous hollow carbon nanospheres, mesoporous carbon nanosheets, and AlN stellar and multi-storey dendrite microcrystals. Our method utilizes the heat of combustion reaction for generating liquid and gaseous reactive species that promote the nucleation and growth of hierarchical microstructures. The studies on the electrochemical characteristics of carbon hierarchical structures revealed that these materials have potential application to fabrication of functional materials for use in supercapacitors and Li–S battery electrodes.
TL;DR: In this paper, Ni-Fe-and Cobased catalysts were characterized by XRD, SEM, EDS, and BET method and revealed a developed nanostructured surface, which explains their high activity in the processes of deep oxidation.
Abstract: SHS-produced complex intermetallics were used as precursors for preparation of Ni–Fe- and Cobased catalysts for deep oxidation of carbon monoxide, propane, and hydrogen. The catalysts were characterized by XRD, SEM, EDS, and BET method and revealed a developed nanostructured surface, which explains their high activity in the processes of deep oxidation. The catalysts under study look promising for incineration of waste and exhaust gases, safeguarding fire/explosion hazards, as well as for use in flameless heat generation, fuel cells, etc.
TL;DR: In this article, existing synthetic procedures for preparation of powders used as raw materials in fabricating optical polycrystalline ceramics such as aluminum oxynitride 9Al2O3 · 5AlN (AlON), yttrium aluminum garnet 5Al 2O3· 3YAG (YAG), and magnesium aluminate spinel Al2O 3 · MgO (MAS).
Abstract: Overviewed are existing synthetic procedures for preparation of powders used as raw materials in fabricating optical polycrystalline ceramics such as aluminum oxynitride 9Al2O3 · 5AlN (AlON), yttrium aluminum garnet 5Al2O3 · 3Y2O3 (YAG), and magnesium aluminate spinel Al2O3 · MgO (MAS). Most promising for practical implementation seems to be solution-combustion synthesis from dehydrated gels containing appropriate inorganic salts and organic fuels.
TL;DR: In this paper, the influence of gas convection on cellular combustion of Ti powder in slit-like reactors was studied experimentally, and free convection of the gases evolved during combustion was found to favor the formation of inclined and cellular combustion fronts.
Abstract: Influence of gas convection on cellular combustion of Ti powder in slit-like reactors was studied experimentally. Heterogeneous combustion in inclined and dead-ended reactors was accompanied by diffusional and convective mass exchange between gaseous reactant and metal powder. Free convection of the gases evolved during combustion was found to favor the formation of inclined and cellular combustion fronts.
TL;DR: In this article, Alon powders were prepared by SHS under nitrogen pressure using KClO4 as a booster and characterized by XRD and SEM, the combustion product obtained under optimized conditions represented pure AlON powder that contained minimal amount of byproducts.
Abstract: AlON powders were prepared by SHS under nitrogen pressure using KClO4 as a booster and characterized by XRD and SEM. The combustion product obtained under optimized conditions represented pure AlON powder that contained minimal amount of byproducts.
TL;DR: In this paper, the authors investigated the phenomenology of calciothermic reduction in model green mixtures containing metal oxides with strong (TiO2) and weak (MoO3) Me-O bonds.
Abstract: Explored was the phenomenology of calciothermic reduction in model green mixtures containing metal oxides with strong (TiO2) and weak (MoO3) Me–O bonds. In case of high affinity metal (Ti), the process occurs in two stages: (1) combustion reaction of Ca with N2 yielding calcium nitride and (2) calciothermic reduction of TiO2 to give TiN. In case of low affinity metal (Mo), the above reactions proceed in parallel, without noticeable time delay.
TL;DR: In this paper, a cast aluminum oxynitrides were prepared by aluminothermic SHS under pressure of nitrogen gas and characterized by time-resolved XRD and chemical analysis.
Abstract: Cast aluminum oxynitrides were prepared by aluminothermic SHS under pressure of nitrogen gas and characterized by time-resolved XRD and chemical analysis. Burning velocity U, material loss caused by sputtering η1, and yield of target material into ingot η2 were measured as a function of nitrogen pressure P(N2). The nitrogen content of synthesized oxynitrides was made as high as 7 wt %. The results may turn helpful in designing high-strength transparent ceramics.
TL;DR: In this article, the extraction of target TiAl powder from SHS-produced TiAl-MgO semiproduct by treatment in acids (H2SO4, HCl,) and NH4Cl solution was investigated.
Abstract: Explored was the extraction of target TiAl powder from SHS-produced TiAl–MgO semiproduct by treatment in acids (H2SO4, HCl,) and NH4Cl solution. Acid leaching was found to be accompanied by marked elution of target TiAl: the yield of TiAl powder was 21 and 33% in case of leaching with H2SO4 and HCl, respectively. But upon leaching with enriched NH4Cl solution at 70–80°C for 30 min, the yield of purified TiAl powder attained a value of 60%.