Corrosion Resistance of Ru-Mo-W-Fe Alloy in Inorganic Acids

In this study, we examined the corrosion resistance of Ru 57 Mo 14.25 W 23.75 Fe 5 , Ru 54 Mo 13.5 W 22.5 Fe 10 , and Ru 48 Mo 12 W 20 Fe 20 alloys in inorganic acids. The alloys were fabricated using the dewetting micro-pulling-down and plasma-melt stamping methods. Immersion tests in H 2 SO 4 at 300 °C for 24 h indicated that Ru-Mo-W-Fe alloys exhibit better corrosion resistance (10 mm y −1 ). Immersion tests at 25 °C in 5% HCl for 72 h and at 100 °C in 50% HF for 24 h also indicated that Ru-Mo-W-Fe alloys are highly corrosion resistant. Electrochemical tests in 1 M HCl and 1 M H 2 SO 4 revealed an increase in the anodic current and the formation of a low charge transfer resistance passive layer corresponding to alloying Fe. XPS analysis revealed that the primary corrosion product formed during polarization of Ru-Mo-W-Fe alloys in 1 M H 2 SO 4 was WO 3 . Notably, WO 3 is kept passivated on pure W during the corrosion in H 2 SO 4 ; however, it is not kept passivated when present on Ru-Mo-W-Fe alloys.