Mospolitech: Alloy for safe storage of hydrogen

2022: Synthesis of an alloy of chemically active metals by the hydride-calcium method

Scientists at the Moscow Polytechnic University for the first time synthesized an alloy of chemically active metals by the hydride-calcium method. Such powders are highly capable of absorbing and retaining hydrogen. An alloy is added to the hydrogen transport vessel that absorbs hydrogen by dissolving it in itself. In order to return hydrogen back to the gas state, it is necessary, for example, to heat this powder to a certain temperature. Mospolitech announced this on December 25, 2022.

The range of use of the alloy is wide: in the automotive industry, metallurgy, chemical industry, nuclear power. Thanks to a special synthesis mechanism, the method allows you to obtain a variety of materials.

Calcium acts here as a reductant of most oxides of industrially important metals. For example, chromium and tantalum oxides easily reduce calcium to pure metals. Further, they interact with each other to form an alloy from which, for example, cylinders for transporting hydrogen are made.

Obtaining refractory alloys of chemically active metals using classical metallurgy is a very expensive and technically complex process. Scientists at the Moscow Polytechnic are developing an alternative technology - powder metallurgy, namely the hydride-calcium method. Its main advantage is the use of cheap oxides as raw components, and the process of producing various materials - from ore to finished product - takes place in one heat treatment cycle, which seriously simplifies the production chain.

We use the oxides of those metals whose alloy we need to obtain, and already during the heat treatment we form the desired composition in the form of a powder. Synthesized powders significantly speed up surface reactions, for example, gas absorption or sintering of metals, if we need to get a compact workpiece, - said Sergey Yudin, Ph.D., associate professor, project manager for the production of chemically active metal alloys by the calcium-hydride method.

As part of scientific work at the Moscow Polytechnic, the hydride-calcium method synthesized for the first time a high-entropy alloy - a material consisting of five elements taken in the same atomic concentrations. So far, a mechanical mixture of metals and an inhomogeneous alloy have been obtained. It is necessary to come to such a state when metals will form a single alloy: only in this case its absorption capacity increases. The task is to synthesize a powder that can absorb about 19 liters of hydrogen for every 100 grams. Now it was possible to achieve the absorption of 12 liters.