Microstructure and hydrogen storage properties of Fe Ti

Microstructure and hydrogen storage properties of Fe. Ti + x wt. % Hf alloys (x = 0, 4, 8 and 12) By : Volatiana RAZAFINDRAMANANA Jean-Louis BOBET and Jacques HUOT At the 2016 CAP Congress – 15 th of June 2016

Outline State of art Metal Hydride Fe-Ti-Hf system Conclusion 1. State of art • Renewable energy • Hydrogen 2. Metal Hydride • Fe. Ti alloy 3. Fe-Ti-Hf system • Microstructure • First hydrogenation properties 4. Conclusion • Outlook • Perspectives 2

Outline State of art Metal Hydride Fe-Ti-Hf system Conclusion Energy : big challenge of the XXI century High population growth Renewable energy Limited reserves of fossil fuel Reduction in emissions of greenhouse gases Urban transport Electronic HYDROGEN « Stationary » application 3

Outline State of art Metal Hydride Fe-Ti-Hf system Conclusion Hydrogen storage H 2 Hydrogen liquid -253°C / 1 atm Compressed 25°C / 350 to 700 atm Best way to store hydrogen Metal hydride 25°C – 1 atm 4

Outline State of art Metal Hydride Fe-Ti-Hf system Metal hydride Metal 1 Conclusion 3 2 1. Adsorption (and dissociation) of hydrogen 2. Diffusion of hydrogen (absorption) 3. Total absorption of hydrogen in the material 5

Outline State of art Metal Hydride Fe-Ti-Hf system Conclusion Fe. Ti alloy Fe Ti Space group Pm 3 m 6

Outline State of art Metal Hydride Fe-Ti-Hf system Conclusion Alternative process Substitute Fe by Mn Zirconium (Zr), Nickel (Ni), Zr 7 Ni 1 O, Hafnium (Hf) Hydrogen absorbed (wt. %) Add some dopants such as : 1, 6 )l a t o ts d i o p (% e n è g ro yd H Fe. Ti+Zirconium 1, 4 1, 2 Fe. Ti+Nickel 1, 0 0, 8 0, 6 0, 4 0, 2 Fe. Ti 0, 0 0 1 2 3 4 5 6 7 Time (h) Temps (h) Activation curves of Fe. Ti and Fe. Ti doped with Zr and Ni, at 25°C under 45 bar of H 2. 7

Outline State of art Metal Hydride Fe-Ti-Hf system Conclusion Microstructure Fe. Ti + 8 wt. %Hf Fe. Ti + 4 wt. %Hf Fe. Ti + 12 wt. %Hf A A A B B B • Matrix (A) + secondary phase (B) • Presence of dendritic phase 8

State of art Outline Metal Hydride Fe-Ti-Hf system Conclusion Element mapping by EPMA Fe. Ti + 4 wt. %Hf Fe. Ti + 8 wt. %Hf Fe. Ti + 12 wt. %Hf Ti Ti Fe Hf Phase Composition Fe. Ti + 4 wt. %Hf Fe. Ti + 8 wt. %Hf Fe. Ti + 12 wt. %Hf Matrix 48. 9 Fe – 49. 0 Ti – 1, 9 Hf 49, 7 Fe – 49, 5 Ti – 0, 7 Hf 49. 3 Fe – 49. 7 Ti – 1. 0 Hf 2 nd phase (1) 53, 2 Fe – 40. 3 Ti – 6, 4 Hf 58, 5 Fe – 39, 9 Ti – 1, 6 Hf 56. 7 Fe – 40. 4 Ti – 2. 8 Hf 2 nd phase (2) 34. 5 Fe – 59. 8 Ti – 4. 7 Hf - 9

Outline State of art Metal Hydride Fe-Ti-Hf system Conclusion Activation properties Fe. Ti + 12 wt. % Hf Fe. Ti + 8 wt. % Hf Need a minimum of 8 wt. % of Hf to activate Fe. Ti No incubation time Kinetic increases with wt. % Hf Fe. Ti + 4 wt. % Hf 4 8 12 % H abs. 0 1. 1 1. 4 Activation curves of Fe. Ti + x wt. %Hf (x = 4, 8 and 12), at 25°C under 20 bar of H 2. 10

Outline State of art Metal Hydride Fe-Ti-Hf system Conclusion Resume Fe. Ti needs a minimum of 8 wt. % Hf to be activated • Role of the Ti rich phase Fe. Ti alloy doped with hafnium has a good industrial base • Low cost • First hydrogenation at room temperature • Fast kinetic Perspective • Identify the 2 nd phase by neutron diffraction 11

CAP Congress organizers J. Huot & JL. Bobet Thank you for your attention Region Aquitaine My colleagues Questions ?