Effect of synthesis temperature on the hydriding behaviors of Mg-Ni-Cu ternary hydrogen storage alloys synthesized by hydriding combustion synthesis

The hydriding combustion synthesis (HCS) is well known as a revolutionary process to produce the hydrogen storage alloy directly from the metal powder mixture with many benefits. In a previous paper, recently focused, hydrogen storage alloy of ternary Mg-Ni-Cu system was successfully produced based on this method, to improve the property of a typical hydrogen storage alloy, Mg ₂Ni. However, since there are still many operating parameters for that production, relationship between operating conditions and the product property is not still well explained. Therefore, the effect of synthesis temperature, as important operating condition, on the hydrogen storage capacity and hydriding rate of the product was mainly examined in this study. Products synthesized at extremely different temperatures of 753, 773, 798 and 823K and hydrogen pressure of 4.0MPa were analyzed, identified and characterized by means of the hydriding curve at 573K, the patterns of X-ray diffraction and the images of scanning electron microscope. The results revealed that the synthesis temperature in a ternary system of hydrogen storage alloys by HCS is more sensitive and more significant than in a binary system to balance two aspects; the product activity for hydriding reaction and the reaction completion of combustion synthesis. The results also indicated that the HCS process was very attractive to produce the ternary Mg-Ni-Cu system of hydrogen storage alloy from the viewpoints of saving energy, saving time and controlling the specific composition of the products.