Mechanical activation of aluminum: 2. Size, shape, and structure of particles

Стрелецкий, А. Н.; Пивкина, Алла Н.; Колбанев, И. В.; Борунова, А. Б.; Лейпунский, И. О.; Ломаева, С. Ф.; Полунина, И. А.; Frolov, Yu. V.; Butyagin, P. Yu.

doi:10.1007/s10595-005-0016-5

Cited by 11 publications

(9 citation statements)

References 1 publication

(12 reference statements)

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“…The preparation procedure for such composite and its structure are described in previous papers [3,4]. The particles of Al + (10-30 wt %) C composite powder consist of nanocrystalline blocks of aluminum distributed in the matrix of amorphous carbon.…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical Activation of Aluminum: 3. Kinetics of Interaction between Aluminum and Water

et al. 2005

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Two regimes of oxidation by water are revealed for nanocrystalline aluminum prepared by the mechanical activation of its mixture with graphite and distributed in the matrix of amorphous carbon. At the temperatures 50 ° C < T < 90 ° C, nanosized aluminum particles interact with water under quasi-isothermal conditions. The main products are hydrogen and pseudoboehmite AlOOH; a low content of bayerite Al(OH) 3 is also formed. After the induction period, the kinetics of interaction can be satisfactorily described by the law of a diminishing sphere. The effective activation energy of the reaction is equal to 61 ± 10 kJ/mol and is identical for the samples of submicron aluminum prepared by different procedures. At temperatures above 90-95 ° C, the oxidation of mechanically activated aluminum by water is transformed into a thermally self-accelerated explosion process. Under these conditions, the oxidation of aluminum to α -Al 2 O 3 is accompanied by an exothermal reaction between the metal and the carbon matrix during which aluminum carbide Al 4 C 3 is formed.

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Section: Introductionmentioning

confidence: 99%

Mechanochemical Activation of Aluminum: 3. Kinetics of Interaction between Aluminum and Water

et al. 2005

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“…The fact of the aluminum grinding is confirmed by the data of electron and atomic force microscopies (see next communication [16]). The graphite crystals are more sensitive to mechanical loading than aluminum and the grinding of graphite makes a major contribution to the value of specific surface area (Fig.…”

Section: Discussionmentioning

confidence: 56%

“…% and demonstrated that, after the treatment in an energy-intensity planetary mill for 40-200 h (we estimated the absorbed energy dose as 150-700 kJ/g), the product nature is determined by the Al/C ratio in the initial mixture. At low carbon content (16)(17)(18)(19)(20)(21)(22)(23) at. %), the mechanochemical treatment results first in the formation of carbide which finally (after 220 h!)…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical activation of aluminum: 1. Joint grinding of aluminum and graphite

et al. 2004

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Changes in the crystal structure and composition of aluminum and graphite powder mixtures in the course of their joint mechanical treatment in a vibration mill were monitored by the adsorption and X-ray diffraction techniques. It was shown that, at absorbed energy doses of 8-10 kJ/g, the grinding and mixing of aluminum with graphite is completed by the formation of an intermediate structure of Al/C composite, where aluminum showed an anomalously high reactivity. The interaction of aluminum with water was used to study its reactivity in the composite. The formation of the composite preceded the stage of chemical interaction between carbon and aluminum atoms.

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“…The mixture was milled for 1 h at 20 Hz frequency, similar to the experiment performed by Streletskii et al [8]. For the mixture, high purity carbon in he form of spectral coal (Ringsdorff, Germany) as used for the preparation of electrodes for dc-ark spectrometry was used.…”

Section: Methodsmentioning

confidence: 99%

Mass spectrometric study of the impurity profile in Zn during reduction-distillation of ZnO with activated and inactivated Al

Anil

Zellmann

Kipphardt

et al. 2010

J. Am. Soc. Mass Spectrom.

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In this work, we report on the application of hyphenated gas source mass spectrometry to study and understand the mechanism of the reduction-distillation of ZnO using Al powder as reductant in its activated and inactivated form. The experiments revealed that the purity of the Zn metal produced were superior using activated Al with respect to inactivated Al, i.e., m5N8 (99.9998% metallic based) versus m5N3. The achieved purity levels of Zn and the absence of high volatile Cd, Mg, and Sb impurities in the gas phase and the material collected were explained with respect to the impurity elements free-energy values, vapor pressure data, and an observed scavenging effect of the Ta crucible, which was supported by the on-line observed mass spectrometric profiles of the residual gas. [1,2]. Several researchers have carried out work on the aluminothermic reduction of ZnO using activated and inactivated Al for the preparation of Al 2 O 3 . However, the reduction was seldom utilized for the purification of zinc [3][4][5]. The present study focuses on the behavior of impurities during the purification of Zn by reduction-distillation of zinc oxide with activated and inactivated Al powder in vacuum. The experiments were conducted at different temperatures and the evolving metal atoms were monitored in real-time to investigate the impurity element's oxide reduction ability and the impurity element's ability for co-distillation. All experiments were performed in a resistance heated vacuum reduction distillation system connected to a gas source mass spectrometer.The activation process of Al is discussed in detail in [6]. The mechanical treatment of Al with added carbon powder as surfactant in vibration milling results in an extremely high chemical activated Al with the removal of inhibiting alumina layer. The addition of graphite also allows one to conserve the powder state of the material without getting oxidized after mechanical milling. The Al powder without pretreatment inherently contains an alumina film at its surface, and is usually denoted as inactivated Al [1]. A smaller particle size presents, in general, a faster reaction rate in the reduction process because of the greater contact area between the reactants; however, in the case of Al, more than particle size, the surface coating matters. ExperimentalThe vacuum reduction distillation system consists of a cylindrically shaped recipient (V ϳ 55 L) on a base plate connected to the mass spectrometer [7]. The schematic of the set-up, originally developed by EMPA, Switzerland, is given in Supplemental Figure S1, which can be found in the electronic version of this article. A turbo pump (PFEIFFER TCP-121) backed by a membrane pump is connected via a vacuum valve. The vacuum achieved was ϳ2.0 ϫ 10 7 mbar measured using a Pirani and a cold cathode gauge. The two copper electrodes mounted side by side to carry the crucible assembly are connected to a high current/low voltage supply. The crucible used for the reduction is made out of tantalum (9.0 mm o.d. ϫ 7.0 mm i.d. ϫ 8 mm ...

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Mechanical activation of aluminum: 2. Size, shape, and structure of particles

Cited by 11 publications

References 1 publication

Mechanochemical Activation of Aluminum: 3. Kinetics of Interaction between Aluminum and Water

Mechanochemical Activation of Aluminum: 3. Kinetics of Interaction between Aluminum and Water

Mechanochemical activation of aluminum: 1. Joint grinding of aluminum and graphite

Mass spectrometric study of the impurity profile in Zn during reduction-distillation of ZnO with activated and inactivated Al

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