Silica-Metal Composite for Hydrogen Storage Applications
In spite of their favourable chemical characteristics, using AB5 alloys as fixed bed for hydrogen storage devices requires proper management of a number of technological aspects. Among these, the mechanical stability of metal particle grains under hydrogen cycling and the overall thermal conductivity of the material bed constitute crucial features. We developed by High Energy Ball Milling HEBM a mechanically stable silica-based AB5 composite with enhanced thermal conductivity. Here, focusing on the material’s physical-chemical properties, we report on the silica-AB5 composite development and characterization. Particularly, we studied the material consolidation process, the resulting composite morphology and the system behaviour under hydrogen loading/unloading cycling.
POWER MEASUREMENTS DURING MECHANICAL MILLING—II. THE CASE OF ''SINGLE PATH CUMULATIVE'' SOLID STATE REACTION
Abstract The electrical power consumptions during the milling process of a planetary mill have been measured. The results of the experiments, carried out with a suitable chosen system, are perfectly in line with previous milling experiments. The dependence of the power consumption during milling from the third power of the rotation speed and the effect of the filling of the milling device on the energy transfer and power consumption have been clearly established and confirmed. The relevance of in situ data acquisition during milling, that can disclose a deeper understanding of the mechanical alloying process, has been discussed within the frame of present and previous results.
Hydrogen absorption and desorption properties of FeTi1.14O0.03 in impure hydrogen containing CO, CO2 and oxygen
The hydrogen absorption and desorption properties of FeTi1.14O0.03 in impure hydrogen containing CO, CO2 or oxygen were studied using either an automated apparatus for hydrogen absorption-desorption cycles combined with a mass spectrometer or gas chromatography. It was found that the effect of CO or CO2 on the hydrogen absorption capacity and the hydrogen absorption-desorption kinetics of the alloy were more deleterious than that of oxygen. The hydrogen absorption capacity degraded after cycling in hydrogen containing CO or CO2 was rapidly restored by cycling in pure hydrogen. However, restoration by cycling in pure hydrogen was more difficult after cycling in hydrogen containing oxygen. Gas analysis revealed that CO and CO2 react with hydrogen to form CH4 and C2H4, and that oxygen reacts with the alloy. It was concluded that the poisoning of oxygen is different from that of CO or CO2. The mechanism of “surface poisoning” by these impurities is discussed.