A study of the characteristics of the combustion of Ti + xC (x &gt; 0.5) powder and granular compositions in a gas coflow

Seplyarskii, B. S.; Кочетков, Р. А.

doi:10.1134/s1990793117050116

Cited by 21 publications

(8 citation statements)

References 6 publications

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“…Another mechanism of combustion in granular systems with a flow of filtered gas is convective, as was first observed during the combustion of Ti + C in a cocurrent flow of nitrogen [20] and then detected without an external gas flow [21]. It was shown that in the convection mode, a hot flow of active gas (in our case, products of the decomposition of PVB) not only heats the surfaces of granules but ignites them as well, ensuring a higher combustion front velocity than indicated by calculations based on TFC and observed in an inert gas flow.…”

Section: Resultsmentioning

confidence: 97%

“…Since the heat of hot DP of PVB (T g − T ig )Uρ b c g is spent on heating the surface layer of granules from the initial temperature to that of ignition (T ig − T 0 )Uρ s c s × 3h*/r, the following balance relation takes place in a stationary combustion wave: (6) where T g is the temperature of the hot gas; T 0 is the initial temperature of the granular mixture; T ig is the temperature of ignition; U is the speed of the combustion front; and h* is the thickness of the surface layer of a granule that the DP of the PVB flow can heat to the temperature of ignition. As in [20,21], the temperature of the α → β transition in titanium T ig = 1155 K was taken as the temperature of ignition when calculating h*. Substituting parameters ρ b /ρ s and c s into expression (6) for mixtures in Tables 2 and 3 at temperatures T g = T ad and T 0 = 293 K, and assuming that c g ≈ 2500 J/(kg K), we obtain an estimate of h*.…”

Section: Resultsmentioning

confidence: 99%

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Effect of the Content of Polyvinyl Butyral on the Synthesis and Phase Composition of Products of Combustion of Ti–Cr–C Granular Mixtures

Seplyarskii

Абзалов

Кочетков

et al. 2021

Russ. J. Phys. Chem.

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A study is performed of the effect the content of an organic binder (polyvinyl butyral) in the range x = 0-1.8 wt % has on the rate of combustion and phase composition of products of the synthesis of granular Ti-Cr-C mixtures of different compositions, with and without nickel-containing binder NiCr. For a mixture of 80% (Ti + C)/20% (3Cr + 2C), an extreme increase in the rate of burning is observed when x is raised to 1.8%. Experimental data are explained using a model of the convective combustion regime in which the gaseous decomposition products of polyvinyl butyral ignite the surfaces of granules. The mechanism of the organic binder appearing behind the visible combustion front is described. Necessary and sufficient conditions for obtaining the mode of convective combustion are formulated. According to XRD data, a change in the content of polyvinyl butyral in the initial mixture does not affect the phase composition of the products of the combustion of the considered mixtures. When grinding the products of combustion, raising the amount of polyvinyl butyral increases the content of the fraction with a characteristic particle size of <250 μm, indicating that such granules are promising for the manufacture of refractory powders.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Effect of the Content of Polyvinyl Butyral on the Synthesis and Phase Composition of Products of Combustion of Ti–Cr–C Granular Mixtures

Seplyarskii

Абзалов

Кочетков

et al. 2021

Russ. J. Phys. Chem.

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“…It is impossible to explain the obtained results based on the assumption of a conductive (filtration) combustion mode. Another possible combustion mechanism of granular systems in the flow of filtering gas is the convective mode [13,14].…”

Section: Resultsmentioning

confidence: 99%

Effect of the Polyvinyl Butyral Content on the Combustion Mode of the (Ti + C) + xNi Granular Mixture

Seplyarskii

Абзалов

Кочетков

et al. 2021

Russ. J. Phys. Chem. B

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In this paper, we study the effect of the polyvinyl butyral content (0-2.3%) on the combustion rate and phase composition of the (Ti + C) + xNi granular mixture, where x = 0, 5, 10, 15, and 20 wt %. At an increased content of the binder, for the first time, a convective combustion mode is discovered due to the ignition of the surface of granules with hot gaseous decomposition products of polyvinyl butyral. This mode is characterized by a higher rate of propagation of the reaction front than follows from the filtration combustion theory. The mechanism for the occurrence of nondecomposed polyvinyl butyral behind the ignition front is explained. According to the X-ray phase analysis data, the phase composition of combustion products does not change with a change in the polyvinyl butyral and nickel content in the mixture and includes only two phases: TiC and Ni. It is shown that when scaling the process of obtaining composite powders from a granular charge (Ti + C) + xNi, it is necessary to ensure the implementation of the conductive combustion mode.

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“…A number of theoretical works [ 18 , 19 , 20 , 21 ] are devoted to this method; however, despite this, there are few experimental works on the combustion of metals and alloys in the co-flow filtration mode. Basically, such works [ 22 , 23 ] are devoted to the study of the co-flow combustion of a mixture of titanium and carbon powders in the nitrogen and/or argon atmosphere. This method is of high practical importance, since it is energy efficient and allows the production of metal nitrides without the use of high pressures.…”

Section: Introductionmentioning

confidence: 99%

AlN Production in Co-Flow Filtration Mode at Low Pressures

et al. 2021

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In this work, the process for obtaining aluminum nitride in the combustion mode of co-flow filtration of a nitrogen–argon mixture was investigated. The combustion of granules consisting of aluminum and aluminum nitride as an inert diluent was studied under conditions of co-current filtration in a flow of nitrogen and a nitrogen–argon mixture in the range of a specific flow rate of 1.5–5.0 cm3/(s∙cm2). It was found that the specific flow rate of the gas mixture and the amount of argon in the nitrogen–argon mixture had a significant effect on the rate and the temperature of combustion. The structure and phase composition of the synthesis products were studied. The maximum achieved yield of the AlN phase was 95 wt.%. Moreover, this method is energy efficient and allows the production of metal nitrides without the use of high-pressure reactors.

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A study of the characteristics of the combustion of Ti + xC (x > 0.5) powder and granular compositions in a gas coflow

Cited by 21 publications

References 6 publications

Effect of the Content of Polyvinyl Butyral on the Synthesis and Phase Composition of Products of Combustion of Ti–Cr–C Granular Mixtures

Effect of the Content of Polyvinyl Butyral on the Synthesis and Phase Composition of Products of Combustion of Ti–Cr–C Granular Mixtures

Effect of the Polyvinyl Butyral Content on the Combustion Mode of the (Ti + C) + xNi Granular Mixture

AlN Production in Co-Flow Filtration Mode at Low Pressures

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