Method for obtaining the nanostructured state of zirconium-based alloys on a ball mill :: SPE RESST

Method for obtaining the nanostructured state of zirconium-based alloys on a ball mill


Currently, modern energy, based on traditional hydrocarbon fuels, feels a deficiency of resources. Therefore, the search for alternative renewable and environmentally friendly sources that can provide humanity with energy for the near future is an urgent task of modern science. One of the most preferred candidates for replacing organic fuel is hydrogen as an energy agent. Using hydrogen to produce energy leads to a sharp reduction in environmental pollution, because when hydrogen burns in oxygen, toxic emissions are completely absent, and the product of the reaction is water.

For a transition to hydrogen energy, it is necessary to solve a number of scientific and technological problems, one of which is the hydrogen storage. One of the most perspective methods of hydrogen storage is metal hydride technology, that is, the accumulation of hydrogen in hydrogen storage alloys with a future desorption when the alloy is heated. The most promising are materials in the structure of which nanoscale cluster elements are present.

The high-energy milling method to create a nanostructured state in zirconium-based alloys is proposed.

The work was performed on the experimental basis of the ISSPMT NSC KIPT.

Upgraded ball milling plant

	For the implementation of high-energy grinding was used ball mill, the view of which is shown in Fig. 1.

Figure 1 - Water-cooled high-energy ball mill

	We proposed to carry out milling in a neutral gas atmosphere, argon. For this purpose, a special sealed container was designed and manufactured, the view of which is shown in Fig. 2

Figure 2 - Container with balls and an overlapping system

Samples preparation

	ZrV₂ alloy was selected as the source material for carrying out the milling experiments. This alloy is perspective for the accumulation of hydrogen, and its properties in the ordinary polycrystalline state are well studied.

	ОA sample of the material was melted in an arc furnace in an atmosphere of pure argon using a tungsten electrode. Metallographic analysis showed that the matrial has a typical dendritic structure (see Figure 3) with a dendrite branch size of about 5 ... 10 μm.

Figure 3 - Metallography of the sample ZrV₂

Methodology of ball milling

	For milling the ZrV₂ alloy strip were loaded into the container together with a set of balls of different diameters (2 – 5 mm). Then, through the exhaust system, air was evacuated and argon was added to a pressure of 1.1 atm.

	The rotational speed of the mill was about 480 turns per minute.

	The milling was carried out in two stages. After the first stage through 30 minutes, an pure ethanol was poured into the container through the filling system, which made it possible to extract a fraction of the resulting powder fraction (fraction 1). Then, the second stage of milling of the material remaining in the container, lasting for 2 hours in alcohol, was performed. As a result, a finely dispersed fraction of ZrV₂ powder was obtained (fraction 2, Fig. 4).

$Appearance of ZrV2 sample after milling (fraction 2)$ Figure 4 - Appearance of ZrV₂ sample after milling (fraction 2)

Results of structural researches

	The scanning electron microscopy (SEM) of ZrV₂ after milling is shown in Fig. 5.

Figure 5 - Microstructure of dispersed powder particles obtained in a ball mill ZrV₂. СЕМ ×1000 (а), ×2000 (б), ×4000 (в), ×5500 (г)

	The results of the diffractometric studies of ZrV₂ samples after grinding in a ball mill (see Figure 6) showed that the powder fractions obtained are either X-ray amorphous or the size of the crystallites (coherent scattering regions) less than 15 nm.

$Diffraction patterns of ZrV2 alloy samples after grinding in a ball mill$ $Diffraction patterns of ZrV2 alloy samples after grinding in a ball mill$ Figure 5 - Diffraction patterns of ZrV₂ alloy samples after grinding in a ball mill: (a) fraction1; (b) frac. 2