Methods of controlling dissolved non-metals

Non-metals dissolved in the liquid metal can influence its properties favourably or unfavourably. Dissolved non-metals can trigger material transformations in the liquid metal or arise as their product. In all these cases, measurement of the concentration and targeted addition or removal of a nonmetal are important.

For metallic structural materials in contact with a liquid metal, the type and extent of material damage is determined not least by the content of oxygen dissolved in the liquid metal. This is measured using electrochemical sensors with a solid electrolyte based on zirconium dioxide. Oxygen is added or removed depending on the indicated deviation from the target value, e.g. by mass transfer with a gas stream with variable oxygen partial pressure. This method is particularly suitable for liquid lead and lead-bismuth alloys and has been developed into an automated oxygen control system for these liquid metals. It is directly transferable to other liquid metals with low to moderate oxygen affinity.

Hydrogen can be produced via high temperature reactions for which liquid metals are also suitable reaction media. One process that is of particular importance for fusion technology or research is the production of the hydrogen isotope tritium by the reaction of neutrons with lithium. The hydrogen sensors currently being developed for use in liquid lithium operate on the electrochemical principle with a liquid salt mixture as the electrolyte.