Mechano-chemical synthesis, microstructural characterization and evaluation of storage properties of nanostructures complex hydrates

• Grant number: 08/07687-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2009
• End date: September 30, 2009
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Walter José Botta Filho
• Grantee: Alexandre Augusto Cesario Asselli
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 05/59594-0 - Properties of amorphous, metastable and nano-structured metallic alloys, AP.TEM

Abstract

Magnesium has been intensively studied as a hydride former due to several advantages, such as high hydrogen storage capacity (7,6wt%, theoretical value), abundance in earth and low cost. However, its mains disadvantages are high stability and poor hydrogen absorption and desorption kinetics. In this context, magnesium complex hydrides such as Mg2NiH4, Mg2CoH5 and Mg2FeH6 appear as interesting alternatives, despite the compromise of hydrogen capacity by better hydrogen sorption kinetics. In this group of hydrides, Mg2FeH6 has the peculiarity that the intermetallic phase Mg2Fe is not stable and as consequence the synthesis of the hydride requires alternatives processing routes. In the present project, we intend to focus in the processing of the nanostructured MG-bases complex hydrides containing additions of catalysts elements such as the transition metals (Ti, Zr, V, Nb and Zn) or transition metals fluorides. The project involves processing, characterization and evaluation of storage properties. Processing will be carried out by reactive high energy ball milling under hydrogen atmosphere. Microstructure of the products will be evaluated by X Ray diffraction, differential scanning calorimetry and electron microscopy. Thermodynamic and kinetics properties associated with hydrogen storage will be evaluated by using a PCT (pressure - composition - temperature) type apparatus for the measurements of absorption and desorption in the equilibrium state.