Electrochemical Mechanism for the Room Temperature Inhibition of Corrosion of Steel by Hydrazine

Abstract

The potentiostaiic characteristics of 321 stainless steel in O₂ -saturated solutions of N₂H₄, of Cl⁻, and of N₂H₄ + Cl⁻, and H₂ -saturated solutions of N₂H₄, are reported. The pitting corrosion of stainless steel by chloride was completely inhibited by addition of more than 10⁻² mol l⁻¹ N₂H₄.

The mechanism of inhibition was through the reaction: N₂H₄→ N₂↑+4H⁺ + 4e⁻, assuming anodic control. It was considered that this mechanism also accounts for the ability of hydrazine to inhibit both general and pitting corrosion of steels at ambient temperatures and at concentrations of ∼ 10⁻³ mol l⁻¹ N₂H₄.