Quantitative analysis of the thermal degassing of a beryllium powder

The thermal degassing of a beryllium powder is investigated using quantitative quadrupole mass spectrometry and the Karl-Fisher technique adapted to measure both water and hydrogen which are the main desorbed species. Methane and carbon dioxide are also measured, but in much lower amounts. Based on the proportionality between the desorbed amounts and the surface area of the various size fractions analysed, all species are shown to originate from the surface of the beryllium particles. The relative proportions of degassed water vapour and hydrogen depend on the thermal conditions of the analysis whereas the total number of moles of both gases remains constant. This shows that the hydrogen is generated by the reduction of surface water molecules or hydroxyls, though a small fraction may result from the normal decomposition process of amorphous surface hydroxide.