HYDROGEN CONCENTRATION DISTRIBUTION IN ELASTIC MEMBRANES DURING DIFFUSION OF HYDROGEN

The diffusion of hydrogen in elastic membranes is capable of inducing stress within them, therefore the hydrogen flux in a diffusion membrane is not only governed by the concentration gradient but also by the stress gradient which it produces. Studies have shown that the lattice-expanding absorption of hydrogen into one face of a membrane which initially contains a uniform non-vanishing distribution of hydrogen immediately induces a hydrogen flux from the opposite face towards the absorption face. This temporary condition is a consequence of the Gorsky effect. An observed reduction of chemical potential of contacting gaseous hydrogen can be correlated with the initial reduction of hydrogen concentration at the opposite face when this is sufficiently active catalytically. A schematic example of a hydrogen concentration profile across the thickness of membranes at times during such experimental situations is discussed.