Study of degradation of hydride forming powders by closed loop cycling under Hydrogen atmosphere

P. LACHARMOISE; A. BARUJ; G. MEYER; B. A. TALAGAÑIS; F. J. CASTRO

Rio de Janeiro

Congreso; Nanomat 2006; 2006

PEMM-COPPE/UFRJ – Brasil

 Most applications of hydride forming materials involve the performance of a large number of hydrogen absorption and desorption cycles during their lifetime. Therefore, the study of the change of technological properties of materials under cycling is a necessary test before industrial application. Cycling tests are usually based on open loop configurations involving a high purity hydrogen source and an exhaust system. This design results in an important hydrogen waste and a potential concern with gas purity. Here we present a novel device to make cycling tests conceived in a closed loop configuration. The setup involves three parts: a reactor where the sample to be studied is loaded, an intermediate volume and a hydrogen source/sink. These components are connected via electrically actuated valves. The main novelty of this device consists in the use of a well-characterized hydride forming material as the hydrogen source and sink. With this innovation, gas economy and gas purity are insured. Moreover, the pressure in the system is easily controlled by adjusting the temperature of the hydride (inducing the restrain or the release of gas). The operation of the equipment and data acquisition is fully automated. The evolution of sample properties during cycling is determined by measuring pressure changes in the reactor chamber. These pressure changes allow us to detect variations in the storage capacity of the material or in the absorption and desorption kinetics.