Effect of dispersed oxide of cerium,lanthanum and thorium on the corrosion behaviour of tungsten in 3.5 wt-% NaCl solution

Abstract

Tungsten has unique physical and chemical properties that make it ideal for high-temperature applications. At room temperature, it is being considered for medical applications due to its protection by an oxide/hydroxide film. However, breakdown of the oxide film and tungsten dissolution can have adverse effects on human health. This study investigates the corrosion of tungsten with and without dispersed oxides of rare-earth elements (ThO₂, CeO₂, and La₂O₃) in a 3 wt-% NaCl solution using electrochemical techniques. The results suggest that tungsten dissolution occurs after the formation of an oxide film, likely WO₃, on the surface of tungsten and dispersed oxide tungsten. La₂O₃ and CeO₂ may decrease the corrosion rate of tungsten, while WThO₂/tungsten has similar corrosion rates to tungsten. The study concludes that CeO₂ or La₂O₃ could replace ThO₂ in tungsten due to the radioactive nature of Th.