Hydrogen-sorption properties, thermal stability and kinetics of hydrogen desorption from the MgH2 phase of the mechanical alloy of Mg with Si, Ti, Fe

• Дата: 2018
• Автори: Ershova, O., Solonin, Y., Dobrovolsky, V., Koval, A.
• Формат: Стаття
• Мова: Українська
• Опубліковано: Institute of Renewable Energy National Academy of Sciences of Ukraine 2018
• Теми: Mechanical alloy; Hydrogen-sorption properties; Thermal stability; Kinetics; Thermodesorption spectroscopy
• Онлайн доступ: https://ve.org.ua/index.php/journal/article/view/52
• Назва журналу: Vidnovluvana energetika

Scientists all over the world have made a lot of studies regardingdevelopment of new hydrogen-accumulating magnesium-basedmaterials. Practical use of these materials is restricted by theproblem, which has not been solved so far. This problem concernstwo well-known significant disadvantages of magnesiumhydride and Mg-based alloys, namely their slow kinetics of hydriding-dehydriding and high dissociation temperature (3000 C at0,1 MPa H2). The main difficulty is that at a decrease in decompositiontemperature an increase in decomposition rate should beachieved (i.e. fast kinetics) while maintaining high hydrogencapacity and cyclic stability of MgH2 hydride phase of receivedmechanical alloys-composites. So a wide range of characteristicsshould be provided that makes a problem today. A small additionto magnesium of alloying element (about 10 at. %) provides ahigh MgH2 hydride phase content and, accordingly, high (morethan 5% wt.) hydrogen-capacity in the synthesized alloycomposite.The mechanical alloy MА (Mg + 5% wt. Si, + 5% wt.Ti + 2% wt. Fe) by the method of reactive mechanicalalloyingwas synthesized. At a hydrogen pressure of 0.1 MPawith the use of thermal desorption spectroscopy, the hydrogencapacity, the thermal stability, the kinetics of hydrogendesorption from the hydroid phase of MgH2 of the obtained MAwere studied.It has been established that the addition of Mg Si,Ti, and Fe leads to a significant improvement in the kinetics ofhydrogen desorption from the obtained PMC of the hydridephase of MgH2.Due to this alloying, the decrease in thethermodynamic stability of MgH2 is not established.Hydrogencapacity of CH MА after reactive grinding for 20 hours.wasfound to be equal to 5.7% wt., after the first cycles of sorptiondesorptionof hydrogen equal to 5.5% wt.