Oxidation-Protective Iridium and Iridium-Rhodium Coating Produced by Electrodeposition from Molten Salts

Abstract

The electrodeposition of oxidation resistant iridium and iridium- rhodium coatings from non-toxic chloride molten salt electrolytes is investigated. Dense, pore free coatings on graphite, carbon- carbon and rhenium substrates were obtained. Electroformed iridium and iridium rhodium alloys have a typical columnar structure and grain size that increases with coating thickness. Influence of the thermal treatment on structure and room temperature mechanical properties of iridium-rhodium is studied. The oxidation of electroformed iridium and iridium- rhodium alloys in stagnant air at 1300 and 1400ºC is investigated and described. The possible applications of electroformed iridium and iridium-rhodium coatings are discussed.