Insoluble electrode comprising an electrodeposited ruthenium-iridium alloy and its use; process for the electrodeposition of the above-mentioned alloy and the preparation of an iridium compound used therefor

摘要

Insoluble electrodes which are especially useful in the electrowinning of nickel in particular comprising an electrically conducting substrate, a barrier layer on the substrate, an electrodeposited ruthenium-iridium intermediate layer which is partially oxidized and an outer layer containing ruthenium dioxide. The ruthenium-iridium layer can usefully be electrodeposited from an aqueous bath containing a soluble ruthenium compound, a soluble iridium compound, a soluble fluoborate salt and fluoboric acid. A preferred iridium compound for use in the bath is one prepared by refluxing a diammonium hexahalo salt of iridium and sulphamic acid in aqueous solution.