Corrosion behaviour of Ta-10 wt-%W alloy in sodium hydroxide solutions

Abstract

The corrosion behaviour of the alloy Ta–10W has been investigated in sodium hydroxide solutions at different temperatures, using open circuit potential measurements together with potentiodynamic polarisation and polarisation resistance studies and electrochemical impedance spectroscopy. The Ta–10W alloy showed passive behaviour in 5, 10 and 15 wt-%NaOH at 25 ° C, in 5 and 10 wt-%NaOH at 50 ° C, and in 5 wt-%NaOH at 75 ° C. In 10 wt-%NaOH at 75 ° C, 15 wt-%NaOH at 50 and 75 ° C and 30 wt-%NaOH at all temperatures, the Ta–10W alloy remained in the active state after the spontaneous dissolution of its superficial air formed oxide. In all cases, the corrosion rates increased with increasing NaOH concentration and temperature.