MgH2-based nanocomposites prepared by short-time high energy ball milling followed by cold rolling: A new processing route

• Published in: International journal of hydrogen energy Vol. 39; no. 9; pp. 4404 - 4413
• Main Authors: Floriano, R., Leiva, D.R., Deledda, S., Hauback, B.C., Botta, W.J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 18.03.2014; Elsevier
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Ball milling; Cold rolling; Crystallites; Desorption; Energy; Exact sciences and technology; Fuels; High-energy ball milling; Hydrogen; Hydrogen storage; Magnesium hydride; Nanocomposites; Nanostructures; Phases; Scanning electron microscopy; Cold rolling; Magnesium hydride; Nanostructures; High-energy ball milling; Hydrogen; Nanocomposite; Nanostructure; Nanostructured materials
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.12.209

A new processing route consisting of a short-time high energy ball milling (HEBM) step followed by cold rolling (CR) to produce MgH2-based nanocomposites was investigated. Samples of pure MgH2 and MgH2-mixtures containing 2 mol% of FeF3 were processed under air atmosphere and their effects on the microstructure and the hydrogen storage properties were studied in detail. X-ray Diffraction (XRD) analysis on all samples revealed crystallite sizes in the nanometer range for the beta-MgH2 and FeF3 phases (beta (beta): ∼8–13 nm and FeF3: ∼16–21 nm). No extra crystallite size reduction was observed for the HEBM + CR samples in comparison with those only cold rolled. Scanning electron microscopy (SEM) evaluation together with elemental composition analysis indicated a finer size distribution of additive particles and also a more intimate level of mixing for the HEBM + CR mixture than for the mixture obtained only by CR. These features were associated with the HEBM step applied before the CR. These characteristics led to a lower hydrogen desorption temperatures and enhanced desorption kinetics behavior for the HEBM + CR samples in comparison with the CR samples. •A new processing route to produce MgH2-based nanocomposites is presented.•Low desorption temperature, very fast desorption kinetic behavior are reported.•Very fine additive particle size distribution and the better level of mixing are reported.