Nanocrystalline HfN produced by mechanical milling: Kinetic aspects

Bab, M. A.; Mendoza‐Zélis, L.; Damonte, L. C.

doi:10.1016/s1359-6454(01)00309-3

Cited by 42 publications

(43 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, during the synthesis of c-HfN by milling Hf in N 2 , 409 it was demonstrated that the degree of nitridation depended on the total supplied energy dose, irrespective of the single impact energy. With increasing impact energy, a net increase in the rate constant was observed, and the milling time required to attain the same conversion degree was consequently reduced.…”

Section: Carbides Nitrides Borides and Silicidesmentioning

confidence: 99%

Hallmarks of mechanochemistry: from nanoparticles to technology

et al. 2013

View full text Add to dashboard Cite

The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

show abstract

Section: Carbides Nitrides Borides and Silicidesmentioning

confidence: 99%

Hallmarks of mechanochemistry: from nanoparticles to technology

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The vial was sealed by an O-ring and connected to a gas reservoir under an initial pressure of 1 MPa, as shown in Fig. 1 [8,9]. The total volume of the system was 260 cm 3 and about 2.7 g material could be produced.…”

mentioning

confidence: 99%

“…The method proposed by Bab et al [9] was adopted to measure the absorption kinetics. Subsequently, the mixture of magnesium powder and the as-cast alloy powder was also milled under the same condition as mentioned above.…”

mentioning

confidence: 99%

Hydrogenation mechanisms of Mg during reaction ball milling

Zhang

Chen

et al. 2004

Journal of Materials Science

View full text Add to dashboard Cite

Magnesium hydrides are considered as the potential hydrogen storage materials.However, high work temperature, slow reaction kinetics and hard activation process limit the practical application of Mg-based hydrides system. Recently, the reaction ball milling (RBM) technique has been successfully introduced to prepare hydrogen storage materials [1,2]. It combines the courses of sample preparation, activation and hydrogenation into one step. Pure Mg milled under the hydrogen atmosphere was studied by Gennari [3]. In his study, the metastable -MgH 2 was generated by the RBM process. A reduction of particle and crystallite size and an increase of specific surface were observed. Unfortunately, only half of Mg was transformed into hydrides and the crystallite size was still very big. Moreover, it took many hours to finish the hydriding process. Some researchers tried to improve the reaction efficiency between In this work, Ti 37.5 V 25 Cr 37.5 (bcc structure) alloy was used as catalyst due to good hydriding properties and high hydrogen storage capacity [7]. Ti 37.5 V 25 Cr 37.5 alloy was prepared using arc melting with electromagnetic stirring (EMS) in an argon atmosphere. The starting materials were of a purity of 99.9% and the alloy was turned and melted for four times to improve the homogeneity. Then the as-cast alloy was crushed into powder, which passed through a 0.5mm screen. Finally, the powder of the as-cast alloy (30wt. %) was mixed with Mg (purity>99%, 100 mesh) and then mechanically milled in a SPEX8000 machine. A cylindrical stainless steel vial was used with the stainless steel balls and the ball to powder ratio is 20:1. The vial was sealed by an O-ring and connected to a gas reservoir under an initial pressure of 1 MPa, as shown in Fig. 1 [8,9]. The total volume of the system was 260 cm 3 and about 2.7 g material could be produced. The milling was carried out for the duration of 5 h.During the milling, small changes in the hydrogen pressure representing absorption of hydrogen by the sample were monitored continuously. The method proposed by Bab et al [9] was adopted to measure the absorption kinetics. Subsequently, the mixture of magnesium powder and the as-cast alloy powder was also milled under the same condition as mentioned above. At selected time, small amount of powder was successively taken out of the vial to characterize the phase structure. For the sake of comparison, the as-cast Ti 37.5 V 25 Cr 37.5 alloy powder was separately milled under the same condition as mentioned above. The powder was characterized at different duration during the milling. Phase structure of the powder was examined using an X-ray diffraction (XRD) machine equipped with a monochromator with Cu Kα The time dependence of the hydrogen absorption during the milling is shown in Fig. 4.In the initial 10 min, an amount of hydrogen, about 1.05 wt % is absorbed quickly;Journal of Materials Science Letters, accepted July 2003 4 then, the hydrogen absorption is slowed down in the following 1 h. The hydrogen content increases rapid...

show abstract

“…Our research group has already reported the attainment of the Mg 2 FeH 6 by RM also with high yields (94%) [9e13]. We have shown previously that the most important parameters for the Mg 2 FeH 6 synthesis are related to the intensity of milling, i.e., the transfer rate of mechanical energy from the milling tools to the reactant materials [14,15]. This implies that processing parameters such as type of mill, rotational speed, ball-to-powder weight ratio and hydrogen pressure are all important in defining the formation yield of the complex hydrides.…”

Section: Introductionmentioning

confidence: 96%